Joseph to president, wellbore technologies Source text for Eikon: Further company coverage:
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The straight horizontal lines represent the wellbore, and the big blue blotch represents the pore pressure.
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The key that unlocks shale drilling is hydraulic fracturing, the process of injecting water, sand and chemicals underground to fracture shale rock and let hydrocarbons flow to the wellbore.
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Tudor's Pope said predictive analytics are already used in oilfield services, but GE and Baker Hughes stand to expand the use of big data in offshore drilling and within the wellbore, in particular.
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Hydraulic fracturing involves the injection of water and other chemicals deep underground where the resulting high-pressure causes cracks to form in the shale rock, allowing oil and gas to trickle into a wellbore.
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He was deeply shaken by the episode, and apparently on the verge of drowning himself in the Thames, when he bumped into a playboy friend, Sir Wellbore Agar, who lured him away with the promise of drink, a woman, beef and Yorkshire pudding.
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The hydraulic fracturing, or fracking, from wells that are drilled is picking up; around Midland the sight of big red lorries gathered around a wellbore like circus wagons, pumping in fluid and sand at high pressure, has become more familiar again (though the amount of drilling is still less than half its level at the peak in 25).
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This will require a pressure in the wellbore greater than formation pressure. # The pressure in the wellbore must also exceed the rock matrix strength. # And finally the wellbore pressure must be greater than one of the three principal stresses in the formation.Jerome Jacob Schubert, 1995, p. 1-4.
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Primary oil well control is the process which maintains a hydrostatic pressure in the wellbore greater than the pressure of the fluids in the formation being drilled, but less than formation fracture pressure. It uses the mud weight to provide sufficient pressure to prevent an influx of formation fluid into the wellbore. If hydrostatic pressure is less than formation pressure, then formation fluids will enter the wellbore. If the hydrostatic pressure of the fluid in the wellbore exceeds the fracture pressure of the formation, then the fluid in the well could be lost into the formation.
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Production tubing is a tube used in a wellbore through which production fluids are produced (travel).
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Techlog is a Schlumberger owned Windows based software platform intended to aggregate all the wellbore information. It allows the user to interpret any log and core data. It addresses the need for a single platform able to support all the wellbore data and interpretation integration workflows, reducing the need for a multitude of highly specialized tools. By bringing the whole workflow into a single platform risk and uncertainty can be assessed throughout the life of the wellbore.
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While drilling an oil or gas well, the top of the wellbore is lined with a casing. The drill string runs through the casing. The annular (ring-shaped) region between the casing and the drill stem is filled with drilling mud which provides hydrostatic pressure to keep the formation fluid from coming up the wellbore. If the pressure of the formation fluid exceeds the hydrostatic pressure of the drilling mud, the oil or gas can blow out of the wellbore.
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Mechanical degradation can also be an issue at the high shear rates experienced in the near-wellbore region.
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Fracturing fluid additive risk management 3\. Baseline groundwater testing 4\. Wellbore construction 5\. Water sourcing and reuse 6\.
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A diagram showing forces at work during differential sticking. The small black arrows represent pressure exerted on the drill pipe from the wellbore, the red arrows represent pressure exerted on the pipe from the formation (smaller than in the wellbore) and the large black arrow represents the net force on the pipe, which is pushing it into the wall. Differential sticking is a problem that occurs when drilling a well with a greater well bore pressure than formation pressure, as is usually the case. The drill pipe is pressed against the wellbore wall so that part of its circumference will see only reservoir pressure, while the rest will continue to be pushed by wellbore pressure.
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A ram-type BOP is similar in operation to a gate valve, but uses a pair of opposing steel plungers, rams. The rams extend toward the center of the wellbore to restrict flow or retract open in order to permit flow. The inner and top faces of the rams are fitted with packers (elastomeric seals) that press against each other, against the wellbore, and around tubing running through the wellbore. Outlets at the sides of the BOP housing (body) are used for connection to choke and kill lines or valves.
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Once the drilling rig has been removed, a wireline truck is used to perforate near the bottom of the well, and then fracturing fluid is pumped. Then the wireline truck sets a plug in the well to temporarily seal off that section so the next section of the wellbore can be treated. Another stage is pumped, and the process is repeated along the horizontal length of the wellbore. The wellbore for the sliding sleeve technique is different in that the sliding sleeves are included at set spacings in the steel casing at the time it is set in place.
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During all well kills, careful attention must be paid to not exceeding the formation strength at the weakest point of the wellbore (or casing/ liner pipes, as appropriate), the "fracture pressure", otherwise fluid will be lost from the wellbore to the formation. Since this lost volume is unknown, it becomes very hard to tell how the kill is proceeding, especially if gas is involved with its large volume change through different parts of the wellbore. Combining a well kill with such a "lost circulation" situation is a serious problem. Lost circulation situations can, of course, also lead to well kill situations.
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Much of the offshore seabed diving work is inspection, maintenance and repair of the blow-out preventers (BOPs) and their permanent guide bases. The primary functions of a blow-out preventer system are to confine well fluid to the wellbore, provide a way to add fluid to the wellbore and to allow controlled volumes of fluid to be withdrawn from the wellbore. Dive work includes assistance with guiding the blowout preventer stack (BOP stack) onto the guide base, inspection of the BOP stack, checking connections, troubleshooting malfunctions of the hydraulic, mechanical and electrical systems, and inspection of the rig's anchors.
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Oil Well Cementing Equipment are essential for the Oil/Gas exploration or production wells and are must used oilfield equipments while drilling a well. Casing pipe will be installed at various depths while drilling. It is held in place by cement, which also provides zone isolation. Casing is run to protect the wellbore from fluids, pressures and wellbore stability problems.
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The cuttings produced by the bit are most typically removed from the wellbore and continuously returned to the surface by the method of direct circulation.
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The type of wellbore completion is used to determine how many times a formation is fractured, and at what locations along the horizontal section. In North America, shale reservoirs such as the Bakken, Barnett, Montney, Haynesville, Marcellus, and most recently the Eagle Ford, Niobrara and Utica shales are drilled horizontally through the producing interval(s), completed and fractured. The method by which the fractures are placed along the wellbore is most commonly achieved by one of two methods, known as "plug and perf" and "sliding sleeve". The wellbore for a plug-and-perf job is generally composed of standard steel casing, cemented or uncemented, set in the drilled hole.
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Underbalanced drilling, or UBD, is a procedure used to drill oil and gas wells where the pressure in the wellbore is kept lower than the static pressure than the formation being drilled. As the well is being drilled, formation fluid flows into the wellbore and up to the surface. This is the opposite of the usual situation, where the wellbore is kept at a pressure above the formation to prevent formation fluid entering the well. In such a conventional "overbalanced" well, the invasion of fluid is considered a kick, and if the well is not shut-in it can lead to a blowout, a dangerous situation.
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Expandable screens are run to depth before being mechanically swaged to a larger diameter. Ideally, expandable screens will be swaged until they contact the wellbore wall.
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In contrast, a vertical well only accesses the thickness of the rock layer, typically . Horizontal drilling reduces surface disruptions as fewer wells are required to access the same volume of rock. Drilling often plugs up the pore spaces at the wellbore wall, reducing permeability at and near the wellbore. This reduces flow into the borehole from the surrounding rock formation, and partially seals off the borehole from the surrounding rock.
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CHOPS creates a wormhole or void where oil gets pulled from the surrounding rocks towards the wellbore. These methods are termed cold production, since they are used at reservoir ambient temperature. When natural lift pressure does not generate sufficient underground pressure or when the pressure declines and is no longer sufficient to move oil through the wellbore, primary production has reached its extraction limit, to be succeeded by secondary recovery.
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Deepwater Horizon drilling rig blowout, 21 April 2010 Kick is defined as an undesirable influx of formation fluid into the wellbore. If left unchecked, a kick can develop into a blowout (an uncontrolled influx of formation fluid into the wellbore). The result of failing to control a kick leads to lost operation time, loss of well and quite possibly, the loss of the rig and lives of personnel.
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Geosteering is the optimal placement of a wellbore based on the results of realtime downhole geological and geophysical logging measurements rather than three-dimensional targets in space. The objective is usually to keep a directional wellbore within a hydrocarbon pay zone defined in terms of its resistivity, density or even biostratigraphy. In mature areas, geosteering may be used to keep a wellbore in a particular section of a reservoir to minimize gas or water breakthrough and maximize economic production from the well. In the process of drilling a borehole, geosteering is the act of adjusting the borehole position (inclination and azimuth angles) on the fly to reach one or more geological targets.
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These maintain structural integrity of the wellbore in the absence of casing, while still allowing flow from the reservoir into the wellbore. Screens also control the migration of formation sands into production tubulars and surface equipment, which can cause washouts and other problems, particularly from unconsolidated sand formations of offshore fields. After a flow path is made, acids and fracturing fluids may be pumped into the well to fracture, clean, or otherwise prepare and stimulate the reservoir rock to optimally produce hydrocarbons into the wellbore. Finally, the area above the reservoir section of the well is packed off inside the casing, and connected to the surface via a smaller diameter pipe called tubing.
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Zero-offset VSPs (A) have sources close to the wellbore directly above receivers. Offset VSPs (B) have sources some distance from the receivers in the wellbore. Walkaway VSPs (C) feature a source that is moved to progressively farther offset and receivers held in a fixed location. Walk-above VSPs (D) accommodate the recording geometry of a deviated well, having each receiver in a different lateral position and the source directly above the receiver.
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Subsea BOPs are connected to the offshore rig above by a drilling riser that provides a continuous pathway for the drill string and fluids emanating from the wellbore. In effect, a riser extends the wellbore to the rig. Blowout preventers do not always function correctly. An example of this is the Deepwater Horizon blowout, where the pipe line going through the BOP was slightly bent and the BOP failed to cut the pipe.
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MWD tools are generally capable of taking directional surveys in real time. The tool uses accelerometers and magnetometers to measure the inclination and azimuth of the wellbore at that location, and they then transmit that information to the surface. With a series of surveys; measurements of inclination, azimuth, and tool face, at appropriate intervals (anywhere from every 30 ft (i.e., 10m) to every 500 ft), the location of the wellbore can be calculated.
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Salt-proximity VSPs (E) are reflection surveys to help define a salt-sediment interface near a wellbore by using a source on top of a salt dome away from the drilling rig. Drill-noise VSPs (F), also known as seismic-while-drilling (SWD) VSPs, use the noise of the drill bit as the source and receivers laid out along the ground. Multi-offset VSPs (G) involve a source some distance from numerous receivers in the wellbore.
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Secondary oil well control is done after the Primary oil well control has failed to prevent formation fluids from entering the wellbore. This process uses "blow out preventer", a BOP, to prevent the escape of wellbore fluids from the well. As the rams and choke of the BOP remain closed, a pressure built up test is carried out and a kill mud weight calculated and pumped inside the well to kill the kick and circulate it out.
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The annular velocity is one of two major variables in the process of cleaning solids (drill cuttings) from the wellbore. By maintaining the annular velocity at certain rates (speeds) in conjunction with the rheological properties of the drilling fluid, the wellbore is kept clean of the drill cuttings to prevent them from settling back down to the bottom and causing drilling problems. The other major variable is the rheology of the drilling fluid. Rheology is sometimes thought of as viscosity to the uninitiated, though improperly.
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Additionally, polymer- bonded explosive compositions containing HMX are used in the manufacture of missile warheads and armor-piercing shaped charges. HMX is also used in the process of perforating the steel casing in oil and gas wells. The HMX is built into a shaped charge that is detonated within the wellbore to punch a hole through the steel casing and surrounding cement out into the hydrocarbon bearing formations. The pathway that is created allows formation fluids to flow into the wellbore and onward to the surface.
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Once the rig is in place, substantial daily expenses are incurred regardless of whether or not a wellbore is actually being drilled. Obviously the faster the wellbore reaches required total depth, the lower the overall cost. Additionally, if the bit fails or wears out, it must be replaced by removing the perhaps several miles of the drill pipe to which it is attached. During this time, known as a "trip", the depth of the hole is not advanced, but much of the operating costs are still incurred.
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Snubbing, also known as hydraulic workover, involves forcing a string of pipe into the well against wellbore pressure to perform the required tasks. The rigup is larger than for coiled tubing and the pipe more rigid.
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In petroleum production, the casing hanger is that portion of a wellhead assembly which provides support for the casing string when it is lowered into the wellbore. It serves to ensure that the casing is properly located. When the casing string has been run into the wellbore it is hung off, or suspended, by a casing hanger, which rests on a landing shoulder inside the casing spool. Casing hangers must be designed to take the full weight of the casing, and provide a seal between the casing hanger and the spool.
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Horizontal directional drill rigs are developing towards large- scale, micro-miniaturization, mechanical automation, hard stratum working, exceeding length and depth oriented monitored drilling. Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple, requiring only a pendulum. Measuring the azimuth (direction with respect to the geographic grid in which the wellbore was running from the vertical), however, was more difficult. In certain circumstances, magnetic fields could be used, but would be influenced by metalwork used inside wellbores, as well as the metalwork used in drilling equipment.
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Regulations typically require that an annular preventer be able to completely close a wellbore, but annular preventers are generally not as effective as ram preventers in maintaining a seal on an open hole. Annular BOPs are typically located at the top of a BOP stack, with one or two annular preventers positioned above a series of several ram preventers. An annular blowout preventer uses the principle of a wedge to shut in the wellbore. It has a donut-like rubber seal, known as an elastomeric packing unit, reinforced with steel ribs.
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Improper fill on trip occurs when the volume of drilling fluid to keep the hole full on a Trip (complete operation of removing the drillstring from the wellbore and running it back in the hole) is less than that calculated or less than Trip Book Record. This condition is usually caused by formation fluid entering the wellbore due to the swabbing action of the drill string, and, if action is not taken soon, the well will enter a kick state.Jerome Jacob Schubert, 1995, pp.4-1-4.Grace, Robert D. (2003).
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Conversely, if a lower pressured fracture network is encountered, fluid from the wellbore can flow very rapidly into the fractures, causing a loss of hydrostatic pressure and creating the potential for a blowout from a formation further up the hole.
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Steam-assisted gravity drainage (SAGD; "Sag-D") is an enhanced oil recovery technology for producing heavy crude oil and bitumen. It is an advanced form of steam stimulation in which a pair of horizontal wells is drilled into the oil reservoir, one a few metres above the other. High pressure steam is continuously injected into the upper wellbore to heat the oil and reduce its viscosity, causing the heated oil to drain into the lower wellbore, where it is pumped out. Dr. Roger Butler, engineer at Imperial Oil from 1955 to 1982, invented the steam assisted gravity drainage (SAGD) process in the 1970s.
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These trips are routinely expected by the crew. Setting surface occurs after the wellbore is drilled to the predetermined surface depth (e.g., after drilling below fresh water strata). The crew will remove the entire drill string to allow surface casing to be emplaced.
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Conventional vertical wells would be unable to economically retrieve these hydrocarbons. Horizontal drilling, extending horizontally through the strata, permits the well to access a much greater volume of the strata. Hydraulic fracturing creates greater permeability and increases hydrocarbon flow to the wellbore.
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The MO BOP was tested to withstand . The device had a lateral valve below the rams on its bottom section. In case of a blowout, a mud pump could be used to pump drilling mud into the wellbore to control the blowout.
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Depth in a well is not necessarily measured vertically or along a straight line. Because wells are not always drilled vertically, there may be two "depths" for every given point in a wellbore: the measured depth (MD) measured along the path of the borehole, and the true vertical depth (TVD), the absolute vertical distance between the datum and the point in the wellbore. In perfectly vertical wells, the TVD equals the MD; otherwise, the TVD is less than the MD measured from the same datum. Common datums used are ground level (GL), drilling rig floor (DF), rotary table (RT), kelly bushing (KB or RKB) and mean sea level (MSL).
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One technique for freeing the stuck pipe, or avoiding the issue to begin with, is to rotate the pipe string while pulling out of the hole. ;Key Seated Stuck Pipe Key seating occurs when the drill string becomes off-centered in the wellbore, and the pipe collars become caught on a deviation in the wellbore. If the rig is able to move the drill string freely downhole, but every time the drill string is pulled upward it becomes stuck at the same point, then it is likely that the pipe is caught in a key seat. ;Cave-in Stuck Pipe An unstable formation can result in a cave in.
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Steam Assisted Gravity Drainage (SAGD) is an enhanced oil recovery technology for producing heavy crude oil and bitumen. It is an advanced form of steam stimulation in which a pair of horizontal wells are drilled into the oil reservoir, one a few metres above the other. High pressure steam is continuously injected into the upper wellbore to heat the oil and reduce its viscosity, causing the heated oil to drain into the lower wellbore, where it is pumped out to a bitumen recovery facility. Dr. Roger Butler, engineer at Imperial Oil from 1955 to 1982, invented steam-assisted gravity drainage (SAGD) in the 1970s.
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Oil well control is the management of the dangerous effects caused by the unexpected release of formation fluid, such as natural gas and/or crude oil, upon surface equipment of oil or gas drilling rigs and escaping into the atmosphere. Technically, oil well control involves preventing the formation gas or fluid (hydrocarbons), usually referred to as kick, from entering into the wellbore during drilling or well interventions. Formation fluid can enter the wellbore if the pressure exerted by the column of drilling fluid is not great enough to overcome the pressure exerted by the fluids in the formation being drilled (pore pressure).Lyons, William C.; Plisga, Gary J. (2005).
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A decrease in pump pressure or increase in pump speed can happen as a result of a decrease in hydrostatic pressure of the annulus as the formation fluids enters the wellbore. As the lighter formation fluid flows into the wellbore, the hydrostatic pressure exerted by the annular column of fluid decreases, and the drilling fluid in the drill pipe tends to U-tube into the annulus. When this occurs, the pump pressure will drop, and the pump speed will increase. The lower pump pressure and increase in pump speed symptoms can also be indicative of a hole in the drill string, commonly referred to as a washout.
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The first response to detecting a kick would be to isolate the wellbore from the surface by activating the blow-out preventers and closing in the well. Then the drilling crew would attempt to circulate in a heavier kill fluid to increase the hydrostatic pressure (sometimes with the assistance of a well control company). In the process, the influx fluids will be slowly circulated out in a controlled manner, taking care not to allow any gas to accelerate up the wellbore too quickly by controlling casing pressure with chokes on a predetermined schedule. This effect will be minor if the influx fluid is mainly salt water.
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The ends of the stems are squared off. When the rams are retracted, there is a passage for the drilling mud. If a blowout begins, the drill string is stopped. Then wrenches are used to manually close the rams around the drill string to seal the wellbore.
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A fishing trip is when a crew is forced to trip pipe to retrieve loose items in the wellbore. This can result from something being dropped in the hole, i.e. a tool, that would cause damage to the bit if the crew attempted to drill with it on bottom.
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The effects of dry drilling range from as minor as destroying a bit to as serious as major damage to the wellbore requiring a new well to be drilled. Dry drilling can also cause severe damage to the drill string, including snapping the pipe, and the drilling rig itself.
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A DOWS system is installed at the bottom of an oil well, it separates oil and water in the wellbore. The oil rich stream is brought to the surface while the water rich stream is pumped into an injection formation without ever coming to the surface. A DOWS system includes many components but the two primary components are an oil/water separation system and a pumping/injection system used to lift oil to the surface and inject the water into a deeper formation. Two basic types of DOWS systems have been developed, one type uses hydrocyclones to mechanically separate oil and water and the other relies on gravity separation that takes place in the wellbore.
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A perforation in the context of oil wells refers to a hole punched in the casing or liner of an oil well to connect it to the reservoir. Creating a channel between the pay zone and the wellbore to cause oil and gas to flow to the wellbore easily. In cased hole completions, the well will be drilled down past the section of the formation desired for production and will have casing or a liner run in separating the formation from the well bore. The final stage of the completion will involve running in perforating guns, a string of shaped charges, down to the desired depth and firing them to perforate the casing or liner.
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A rounded profile float shoe with an integral check valve attached to the bottom of a casing string prevents reverse flow, or U-tubing, of cement slurry from the annulus into the casing or flow of wellbore fluids into the casing string as it is run. The float shoe also guides the casing toward the center of the hole to minimize hitting rock ledges or washouts as the casing is run into the wellbore. By "floating" casing in, hook weight is reduced. With controlled or partial fill-up as the string is run, the casing string can be floated into position, precluding the need for the rig to carry the entire weight of the casing string.
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The company operates across four major service areas: Drilling, Surveying, Wireline, and Support. Drilling Services encompasses a wide range of technologies designed for directional drilling applications, including performance motors, measurement-while-drilling (MWD) tools, rotary steerable systems (RSS), and gyro-while-drilling (GWD) tools, the latter of which was invented by Gyrodata in 2002 to use real-time gyro steering and surveying data while drilling. Surveying Services provides gyroscopic surveys designed to improve wellbore placement using both spinning-mass and solid-state technology, depending on the application. Wireline Services covers not only traditional wireline and cased-hole logging solutions but unique offerings in high-density wellbore tortuosity logging and cement bond logging.
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For bits to be used in these situations, the ability of the bit to be more easily "steered" during drilling has become a third, possibly driving, primary goal of the design. The ability of a bit design to satisfy the two primary goals is constrained by a number of factors, most importantly the wellbore diameter. Other constraints are dictated by its intended use: formation type (hardness, plasticity, abrasiveness) to be drilled, operating environment at depth (temperature, pressure, corrosiveness), the capabilities of the equipment used in the operation (rotating speed, available weight on bit, pump horsepower) and the angle of the wellbore (vertical, directional, horizontal). Modern drill bit designs try to balance these constraints to achieve the primary goals.
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Sometimes, productivity may be hampered due to the residue of completion fluids, heavy brines, in the wellbore. This is particularly a problem in gas wells. In these cases, coiled tubing may be used to pump nitrogen at high pressure into the bottom of the borehole to circulate out the brine.
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Retrieved 8 April 2011. Oil well control also includes monitoring a well for signs of impending influx of formation fluid into the wellbore during drilling and procedures, to stop the well from flowing when it happens by taking proper remedial actions.Schlumberger article, "Well control", "Schlumberger OilField Glossary". Retrieved 9 April 2011.
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There are a few disadvantages to this method as well. The resolution of the surface wave inversion method is not nearly as resolved as a seismic collection done in a wellbore. There is also the possibility for non-unique solutions to dispersion curves (several sets of parameters can yield the same dispersion curve).
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In workover operations, a well-servicing unit is used to winch items in and out of the wellbore. The line used to raise and lower equipment can be braided steel wireline or a single steel slickline. Workover operations conducted can include well clean-up, setting plugs, production logging and perforation through explosives.
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The consequences of lost circulation can be as little as the loss of a few dollars of drilling fluid, or as disastrous as a blowout and loss of life, so close monitoring of tanks, pits, and flow from the well, to quickly assess and control lost circulation, is taught and practiced. If the amount of fluid in the wellbore drops due to lost circulation (or any other reason), hydrostatic pressure is reduced, which can allow a gas or fluid which is under a higher pressure than the reduced hydrostatic pressure to flow into the wellbore. Another consequence of lost circulation is dry drilling. Dry drilling occurs when fluid is completely lost from the well bore without actual drilling coming to a stop.
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Sometimes fluid will be added to the wellbore to assist in bailing by bringing up the pressure, and also lubricating the downhole solid. Because the pressure inside the bailer is much less than the downhole wellbore pressure, any solids that are loose enough are 'sucked up' by the vacuum formed when the bottom plug is sheared and travels upwards through the barrel, followed by the solids. At the same time, due to the changed from negative pressure to positive pressure, the top plug pops out (and is caught by the top part of the tool), and excess flow is directed out through the 10 mm ports on the sides of the top of the tool. These ports allow the barrel to fill more readily.
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Wireline truck Used to place and recover wellbore equipment, such as plugs, gauges and valves, slicklines are single-strand non-electric cables lowered into oil and gas wells from the surface. Slicklines can also be used to adjust valves and sleeves located downhole, as well as repair tubing within the wellbore. Wrapped around a drum on the back of a truck, the slickline is raised and lowered in the well by reeling in and out the wire hydraulically. Braided line can contain an inner core of insulated wires which provide power to equipment located at the end of the cable, normally referred to as electric line, and provides a pathway for electrical telemetry for communication between the surface and equipment at the end of the cable.
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In addition to controlling the downhole (occurring in the drilled hole) pressure and the flow of oil and gas, blowout preventers are intended to prevent tubing (e.g. drill pipe and well casing), tools and drilling fluid from being blown out of the wellbore (also known as bore hole, the hole leading to the reservoir) when a blowout threatens. Blowout preventers are critical to the safety of crew, rig (the equipment system used to drill a wellbore) and environment, and to the monitoring and maintenance of well integrity; thus blowout preventers are intended to provide fail-safety to the systems that include them. The term BOP (pronounced B-O-P, not "bop")"Blow Out Preventer (BOP)", video content produced by Transocean.
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Tractors are electrical tools used to push the toolstring into hole, overcoming wireline's disadvantage of being gravity dependent. These are used for in highly deviated and horizontal wells where gravity is insufficient, even with roller stem. They push against the side of the wellbore either through the use of wheels or through a wormlike motion.
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The mud in the wellbore must exert enough hydrostatic pressure to equal the formation pore pressure. If the fluid's hydrostatic pressure is less than formation pressure the well can flow. The most common reason for insufficient fluid density is drilling into unexpected abnormally pressured formations. This situation usually arises when unpredicted geological conditions are encountered.
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The aquifer parameters obtained from a slug test are typically less representative of the aquifer surrounding the well than an aquifer test which involves pumping in one well and monitoring in another. Complications arise from near-well effects (i.e., well skin and wellbore storage), which may make it difficult to get accurate results from slug test interpretation.
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BOP stacks frequently utilize both types, typically with at least one annular BOP stacked above several ram BOPs. Blowout preventers are used on land wells, offshore rigs, and subsea wells. Land and subsea BOPs are secured to the top of the wellbore, known as the wellhead. BOPs on offshore rigs are mounted below the rig deck.
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After the "frack," oil or gas is extracted and 30–70% of the frack fluid, i.e. the mixture of water, chemicals, sand, etc., flows back to the surface. Many gas- bearing formations also contain water, which will flow up the wellbore to the surface along with the gas, in both hydraulically fractured and non- hydraulically fractured wells.
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Many wellbore conditions increase the likelihood of swabbing on a trip. Swabbing (piston) action is enhanced when the pipe is pulled too fast. Poor fluid properties, such as high viscosity and gel strengths, also increase the chances of swabbing a well in. Additionally, large outside diameter (OD) tools (packers, scrapers, fishing tools, etc.) enhance the piston effect.
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During primary recovery, the natural pressure of the reservoir or gravity drive oil into the wellbore, combined with artificial lift techniques (such as pumps) which bring the oil to the surface. But only about 10 percent of a reservoir's original oil in place is typically produced during primary recovery. But petroleum isn't the only thing trapped in the earth. Water hides there too.
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Though there are many problems that occur to warrant the tripping of pipe. Downhole tools such as MWD (measurement while drilling), LWD (logging while drilling) or mud motors break down quite often. Another common reason for tripping is to replace damaged drill pipe. It is important to get the pipe out of the wellbore quickly and safely before it can snap.
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Another major cause is known as a "twist off". Twisting off is when the drill string parts by failing catastrophically under the torsional stress. This may happen if the drill string below is pinched in the wellbore, or as the result of a structural weakening of the pipe caused by a washout or a crack in a threaded connection member.
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The investigation and prediction of Asphaltene deposition at the wellbore, Khoram A., 2014. 131\. Classification of layers and formations in one of Iran's oil field with sonic log and selection of appropriate Bit, S. Parvezi, 2014. 132\. Investigation the effect of molecular diffusion and compositional gradient on miscible displacement of heavy and light in oil Iranian reservoirs, S. Rahbani, 2014. 133\.
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The well suffered a complete loss of circulation at 12:50 p.m. local time on the 26th May 2006, which was between 1.5-4.75 hours after three large aftershocks. A loss of circulation happens when drilling mud—necessary for maintenance of wellbore stability—that is pumped down a shaft does not return to the surface but is lost into some opening or a fault system.
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This allows opposing electrical charges to be applied at either end. Laboratory experiments have demonstrated that electrical continuity is unaffected by kerogen conversion and that hydrocarbons are expelled from heated oil shale even under in situ stress. Planar heaters should be used because they require fewer wells than wellbore heaters and offer a reduced surface footprint. The shale oil is extracted by separate dedicated production wells.
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An underground blowout is a special situation where fluids from high pressure zones flow uncontrolled to lower pressure zones within the wellbore. Usually this is from deeper higher pressure zones to shallower lower pressure formations. There may be no escaping fluid flow at the wellhead. However, the formation(s) receiving the influx can become overpressured, a possibility that future drilling plans in the vicinity must consider.
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A hydrostatic bailer functions like a 'vacuum', and is used to suck up unwanted solids from the wellbore. A hydrostatic bailer is generally around 2.5 meters long and is tubular looking, with two 10 mm holes on opposing sides at the top of the tool, and a hole in the bottom. A hydrostatic bailer uses a pinned plug with o-ring seals at the bottom, and a plug at the top to maintain the surface pressure that it was assembled at (nominally around 100 kPa) all the way to the bottom of the well, whereupon it is spudded into the downhole solids, which ideally pushes the shoe into the bottom plug, which shears the pin on the bottom plug. An oil or gas well's pressure downhole is always more than atmospheric pressure at surface, due to the formation pressure, and a combination of depth and hydrostatic weight of wellbore fluids.
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A schematic of a typical oil well being produced by a pumpjack, which is used to produce the remaining recoverable oil after natural pressure is no longer sufficient to raise oil to the surface The production stage is the most important stage of a well's life; when the oil and gas are produced. By this time, the oil rigs and workover rigs used to drill and complete the well have moved off the wellbore, and the top is usually outfitted with a collection of valves called a Christmas tree or production tree. These valves regulate pressures, control flows, and allow access to the wellbore in case further completion work is needed. From the outlet valve of the production tree, the flow can be connected to a distribution network of pipelines and tanks to supply the product to refineries, natural gas compressor stations, or oil export terminals.
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Additional measurements can also be taken of natural gamma ray emissions from the rock; this helps broadly to determine what type of rock formation is being drilled, which in turn helps confirm the real-time location of the wellbore in relation to the presence of different types of known formations (by comparison with existing seismic data). Density and porosity, rock fluid pressures and other measurements are taken, some using radioactive sources, some using sound, some using electricity, etc.; this can then be used to calculate how freely oil and other fluids can flow through the formation, as well as the volume of hydrocarbons present in the rock and, with other data, the value of the whole reservoir and reservoir reserves. An MWD downhole tool is also "high-sided" with the bottom hole drilling assembly, enabling the wellbore to be steered in a chosen direction in 3D space known as directional drilling.
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In April 2017, the company acquired Seventy Seven Energy. The deal included Seventy Seven’s affiliates: Great Plains Oilfield Rental, Nomac Drilling (now part of Patterson-UTI Drilling), and Performance Technologies (now part of Universal Pressure Pumping). In October 2017, the company acquired MS Energy Services (now MS Directional). In February 2018, the company acquired Superior QC, a provider of software used to improve the accuracy of horizontal wellbore placement.
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From Pills to Penicillin: The Beecham Story – by H. G. Lazell, Published by Heinemann - London (1975) In time some bacterial strains developed resistance to these antibiotics, such as the MRSA (for methicillin-resistant Staphylococcus aureus). The site became Beecham's Chemotherapeutic Research Centre.New Scientist January 1977 The site is now a housing estate. In August 2018, retrospective planning permission was granted by Surrey County Council for a secondary oil wellbore in Brockham.
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An offset well is an existing wellbore that may be used as a guide for planning a well. Many offsets could be referred to in the planning of a well, to identify subsurface geology and pressures. Offset well data may be combined with seismic data and prior experience. Where offset data is lacking, well planners will be more conservative, allowing for a greater range of contingencies and expenses.
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Propellant stimulations can be a very economical way to clean up nearbore damage. Propellants are a low-explosive material that generate large amounts of gas downhole very rapidly. The gas pressure builds in the wellbore, increasing tension in the rock until it becomes greater than the breakdown pressure of the formation. Fracture length and fracture pattern are highly dependent on the type of propellant stimulation tool that is used.
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This displacement of the drill string (the steel) will leave out a volume of space that must be replaced with an equal volume of mud. If the replacement is not done, the fluid level in the wellbore will drop, resulting in a loss of hydrostatic pressure (HSP) and bottom hole pressure (BHP). If this bottom hole pressure reduction goes below the formation pressure, a kick will definitely occur.
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If there is an unexplained increase in the volume of surface mud in the pit (a large tank that holds drilling fluid on the rig), it could signify an impending kick. This is because as the formation fluid feeds into the wellbore, it causes more drilling fluid to flow from the annulus than is pumped down the drill string, thus the volume of fluid in the pit(s) increases.
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Although less exposed to wellbore fluids, casing strings too have been known to lose integrity. On occasion, it may be deemed economical to pull and replace it. Because casing strings are cemented in place, this is significantly more difficult and expensive than replacing the completion string. If in some instances the casing cannot be removed from the well, it may be necessary to sidetrack the offending area and recomplete, also an expensive process.
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This movement compresses a large spring and pushes the flapper downwards to open the valve. When hydraulic pressure is removed, the spring pushes the sleeve back up and causes the flapper to shut. In this way, it is failsafe and will isolate the wellbore in the event of a loss of the wellhead. The full designation for a typical valve is 'tubing retrievable, surface controlled, subsurface safety valve', abbreviated to TR-SCSSV.
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As part of the role of the DHSV to isolate the surface from wellbore fluids, it is necessary for the valve to be positioned away from the well where it could potentially come to harm. This implies that it must be placed subsurface in all circumstances, i.e. in offshore wells, not above the seabed. There is also the risk of cratering in the event of a catastrophic loss of the topside facility.
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Coiled tubing is often used as a production string in shallow gas wells that produce some water. The narrow internal diameter results in a much higher velocity than would occur inside conventional tubing or inside the casing. This higher velocity assists in lifting liquids to surface, liquids which might otherwise accumulate in the wellbore and eventually "kill" the well. The coiled tubing may be run inside the casing instead or inside conventional tubing.
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BP started a second relief well using Transocean's GSF Development Driller II on May 16, 2010. The well was successfully sealed off from flow into the sea on August 4, 2010 by a "static kill" (injection of heavy fluids and cement into the wellhead at the mudline). To further ensure the plugging of the original well, the first relief well established communication with the original wellbore near total depth and injected heavy fluids and cement.
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Ram BOPs are typically designed so that well pressure will help maintain the rams in their closed, sealing position. That is achieved by allowing fluid to pass through a channel in the ram and exert pressure at the ram's rear and toward the center of the wellbore. Providing a channel in the ram also limits the thrust required to overcome well bore pressure. Single ram and double ram BOPs are commonly available.
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This involves the injection of chemicals to eat away at any skin damage, "cleaning up" the formation, thereby improving the flow of reservoir fluids. A strong acid (usually hydrochloric acid) is used to dissolve rock formations, but this acid does not react with the Hydrocarbons. As a result, the Hydrocarbons are more accessible. Acid can also be used to clean the wellbore of some scales that form from mineral laden produced water.
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Gyrodata, Incorporated is a privately owned company headquartered in Houston, Texas. The company has principal offices in Aberdeen, Scotland and Kuala Lumpur, Malaysia. Gyrodata is a leading provider of technology and services, including directional drilling, gyroscopic surveying, and wellbore logging, to the upstream oil and gas industry. The company’s drilling, surveying, wireline, and support services help customers place wells more precisely and accurately, improve hydrocarbon recovery factors, and reduce project lifecycle costs.
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Known challenges with caliper logging include borehole spiralling. The position of the drill bit may precess as it drills, leading to spiraling shapes in the wellbore wall, as if the hole had been drilled by a screw. If the arms of the caliper log follow the grooves of the spiral, it will report too high an average diameter. Moving in and out of the grooves, the caliper will give erratic or periodically varying readings.
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Theys, P. (1999): Log data acquisition and quality control, Editions Technip, Paris, France, 330p. Unlike measurements in well-known and controlled laboratory conditions, logging is performed in-situ and can be affected by different possible failure sources and susceptible to systematic and random errors. The objective of wireline logging job is to obtain a permanent continuous record of the rock properties penetrated by the wellbore with the end result of wireline logs, fluid, and rock samples.
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The highly energized plasma is capable of overcoming nearly any wellbore condition, and has a cutting success rate of 77%. The RCT does not contain explosives; this greatly reduces transportation costs and logistical problems.MCR Oil Tools-RCT ;Drill Collar Severing Tool (DCST) The Drill Collar Severing Tool is often used to separate heavy weight drill pipe or drill collars. The DCST contains an explosive charge at either end of the tool; both charges are detonated simultaneously.
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For more advanced applications, microseismic monitoring is sometimes used to estimate the size and orientation of induced fractures. Microseismic activity is measured by placing an array of geophones in a nearby wellbore. By mapping the location of any small seismic events associated with the growing fracture, the approximate geometry of the fracture is inferred. Tiltmeter arrays deployed on the surface or down a well provide another technology for monitoring strain Microseismic mapping is very similar geophysically to seismology.
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These can generally be removed in two separate pieces to facilitate large items, e.g. drill bits, to pass through the rotary table. The large gap in the center of the rotary bushings is referred to as the "bowl" due to its appearance. The bowl is where the slips are set to hold up the drill string during connections and pipe trips as well as the point the drill string passes through the floor into the wellbore.
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Soon after, a British scouting boat returned, having found Johnstone Strait. The two expeditions parted ways shortly afterwards, on July 13, 1792, with the British sailing through Discovery Passage and Johnstone Strait, while the Spanish went via Cordero Channel, Chancellor Channel, and Wellbore Channel. According to Galiano's report, Vancouver considered Cordero Channel too dangerous for his ships. From their anchorage between West Redonda Island and Cortes Island, the Spanish set sail for Cordero Channel on July 13, 1792.
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Drilling bits are attachments that are added to the end of a drillstring to perform the cutting necessary to penetrate the many rock layers between Earth's surface and oil/gas reservoirs. Once a hole is drilled, appropriate casings may be inserted to seal the wellbore formation. Howard Hughes designed and patented the first roller-cone bit in 1909. His design had two rotating cones, but was evolved to a tricone bit (see image above) in the 1930s.
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An illustration of shale gas compared to other types of gas deposits. Because shales ordinarily have insufficient permeability to allow significant fluid flow to a wellbore, most shales are not commercial sources of natural gas. Shale gas is one of a number of unconventional sources of natural gas; others include coalbed methane, tight sandstones, and methane hydrates. Shale gas areas are often known as resource playsDan Jarvie, "Worldwide shale resource plays," PDF file, NAPE Forum, 26 August 2008.
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For this reason, the effectiveness of a bit is often measured as drilling cost per foot of hole drilled, where a lower number indicates a higher performing bit. Note that the cost of the bit itself often is a rather small part of the overall drilling cost. Within the last couple of decades, a third design goal has become important in some cases. Many wells today are drilled using directional technology, where the wellbore is intentionally directed from vertical.
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As a consequence many operators, when faced with uneven stunted steam chamber development, allow a small quantity of steam to enter into the producer to keep the bitumen in the entire wellbore hot hence keeping its viscosity low with the added benefit of transferring heat to colder parts of the reservoir along the wellbore. Another variation sometimes called Partial SAGD is used when operators deliberately circulate steam in the producer following a long shut-in period or as a startup procedure. Though a high value of sub-cool is desirable from a thermal efficiency standpoint as it generally includes reduction of steam injection rates but it also results in slightly reduced production due to a corresponding higher viscosity and lower mobility of bitumen caused by lower temperature. Another drawback of very high sub-cool is the possibility of steam pressure eventually not being enough to sustain steam chamber development above the injector, sometimes resulting in collapsed steam chambers where condensed steam floods the injector and precludes further development of the chamber.
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During a fracking operation thousands of gallons of fluid and sand are pumped down one well to open up the formation surrounding that wellbore. Often large amounts of that proppant and fluid will travel through the formation and into a nearby well. This sand can lodge on top of a packer or coil tubing in the well sticking the pipe. ;Tubing Stuck in Production Wells: Tubing in production wells is often exposed to a number of highly corrosive chemicals, such as H2S.
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If not controlled, it can exceed 70% of the injected volume. This may result in formation matrix damage, adverse formation fluid interaction, and altered fracture geometry, thereby decreasing efficiency. The location of one or more fractures along the length of the borehole is strictly controlled by various methods that create or seal holes in the side of the wellbore. Hydraulic fracturing is performed in cased wellbores, and the zones to be fractured are accessed by perforating the casing at those locations.
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A series of consecutive surveys are needed to track the progress and location of a wellbore. Prior experience with rotary drilling had established several principles for the configuration of drilling equipment down hole ("bottom hole assembly" or "BHA") that would be prone to "drilling crooked hole" (i.e., initial accidental deviations from the vertical would be increased). Counter- experience had also given early directional drillers ("DD's") principles of BHA design and drilling practice that would help bring a crooked hole nearer the vertical.
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INTEQ also originally incorporated the drilling fluids division of Baker Hughes which consisted of Milpark and others. This division was called 'INTEQ drilling fluids' which provided the premier brands in oil and gas well drilling muds and wellbore cleaning fluids. In 2003, these product lines were spun off to form the separate entity of Baker Hughes Drilling Fluids (BHDF), with INTEQ continuing as the Drilling and Evaluation (D&E;) company. INTEQ provides directional Drilling, MWD/LWD, surface logging (mud logging) and coring services.
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Blind rams (also known as sealing rams), which have no openings for tubing, can close off the well when the well does not contain a drill string or other tubing, and seal it. Patent Drawing of a Varco Shaffer Ram BOP Stack. A shear ram BOP has cut the drillstring and a pipe ram has hung it off. Schematic view of closing shear blades Shear rams are designed to shear the pipe in the well and seal the wellbore simultaneously.
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In cased hole completions (the majority of wells), once the completion string is in place, the final stage is to make a connection between the wellbore and the formation. This is done by running perforation guns to blast holes in the casing or liner to make a connection. Modern perforations are made using shaped explosive charges, similar to the armor-penetrating charge used on antitank rockets (bazookas). Sometimes once the well is fully completed, further stimulation is necessary to achieve the planned productivity.
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This means creating and extending fractures from the perforation tunnels deeper into the formation, increasing the surface area for formation fluids to flow into the well, as well as extending past any possible damage near the wellbore. This may be done by injecting fluids at high pressure (hydraulic fracturing), injecting fluids laced with round granular material (proppant fracturing), or using explosives to generate a high pressure and high speed gas flow (TNT or PETN up to ) and (propellant stimulation up to ).
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When pipe snaps or a part of the bit breaks off, the crew has to recover all of the separated items from the wellbore. Recovering snapped pipe usually involves placing a specialized tool (an "overshot") with grips set inside of it over the broken pipe in an attempt to capture it. The grip works in a manner similar to Chinese fingercuffs. Sometimes the jagged top of the fish must be milled back to a round outside shape before the overshot can slip over it.
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Logging of the open hole may take place at various depths while drilling, and almost always at the end of the drilling operation. The drill string will be removed from the wellbore to allow a logging crew to conduct a survey of the well. After the logging is completed at total depth, the crew will run the drill string back into the well and then proceed to lay it down when coming out of the hole prior to installing the final set of casing (the "production casing").
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A production packer is a standard component of the completion hardware of oil or gas wells used to provide a seal between the outside of the production tubing and the inside of the casing, liner, or wellbore wall. Based on their primary use, packers can be divided into two main categories: production packers and service packers. Production packers are those that remain in the well during well production. Service packers are used temporarily during well service activities such as cement squeezing, acidizing, fracturing and well testing.
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Nitroglycerin has been used in conjunction with hydraulic fracturing, a process used to recover oil and gas from shale formations. The technique involves displacing and detonating nitroglycerin in natural or hydraulically induced fracture systems, or displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized TNT. Nitroglycerin has an advantage over some other high explosives that on detonation it produces practically no visible smoke. Therefore, it is useful as an ingredient in the formulation of various kinds of smokeless powder.
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Opposing rams (plungers) in the ram cavity translated horizontally, actuated by threaded ram shafts (piston rods) in the manner of a screw jack. Torque from turning the ram shafts by wrench or hand wheel was converted to linear motion and the rams, coupled to the inner ends of the ram shafts, opened and closed the well bore. Such screw jack type operation provided enough mechanical advantage for rams to overcome downhole pressures and seal the wellbore annulus. Hydraulic rams BOPs were in use by the 1940s.
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In hydraulic fracturing, well operators force water mixed with a variety of chemicals through the wellbore casing into the rock. The high pressure water breaks up or "fracks" the rock, which releases gas from the rock formation. Sand and other particles are added to the water as a proppant to keep the fractures in the rock open, thus enabling the gas to flow into the casing and then to the surface. Chemicals are added to the fluid to perform such functions as reducing friction and inhibiting corrosion.
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Volume II of the report cited above contains the report of the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE). That volume states that a central cause of the blowout was failure of a cement barrier in the production casing string, a high‐strength steel pipe set in a well to ensure well integrity and to allow future production. The failure of the cement barrier allowed hydrocarbons to flow up the wellbore, through the riser and onto the rig, resulting in the blowout.
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MWD typically concerns measurement taken of the wellbore (the hole) inclination from vertical, and also magnetic direction from north. Using basic trigonometry, a three-dimensional plot of the path of the well can be produced. Essentially, a MWD operator measures the trajectory of the hole as it is drilled (for example, data updates arrive and are processed every few seconds or faster). This information is then used to drill in a pre-planned direction into the formation which contains the oil, gas, water or condensate.
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Mexico's state-owned oil company Pemex (Petróleos Mexicanos) was drilling a deep oil well when the drilling rig Sedco 135 lost drilling mud circulation. In modern rotary drilling, mud is circulated down the drill pipe and back up the wellbore to the surface. The goal is to equalize the pressure through the shaft and to monitor the returning mud for gas. Without the counter-pressure provided by the circulating mud, the pressure in the formation allowed oil to fill the well column, blowing out the well.
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Drilling into an adjacent well is a potential problem, particularly in offshore drilling where a large number of directional wells are drilled from the same platform. If the drilling well penetrates the production string of a previously completed well, the formation fluid from the completed well will enter the wellbore of the drilling well, causing a kick. If this occurs at a shallow depth, it is an extremely dangerous situation and could easily result in an uncontrolled blowout with little to no warning of the event.
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These conditions need to be recognized in order to decrease the likelihood of swabbing a well in during completion/workover operations. As mentioned earlier, there are several computer and calculator programs that can estimate surge and swab pressures. Swabbing is detected by closely monitoring hole fill-up volumes during trips. For example, if three barrels of steel (tubing) are removed from the well and it takes only two barrels of fluid to fill the hole, then a one barrel kick has probably been swabbed into the wellbore.
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Mud logging technicians in an oil field drilling operation determine positions of hydrocarbons with respect to depth, identify downhole lithology, monitor natural gas entering the drilling mud stream, and draw well logs for use by oil company geologist. Rock cuttings circulated to the surface in drilling mud are sampled and discussed. The mud logging company is normally contracted by the oil company (or operator). They then organize this information in the form of a graphic log, showing the data charted on a representation of the wellbore.
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Coalbed methane as a resource apart from coal mining began in the early 1980s in the Black Warrior Basin of northern Alabama. The American Public Gas Association under a U. S. Department of Energy grant funded a three-well research program in 1980 to produce coalbed methane at Pleasant Grove, Alabama. This program is the first aimed at commercial recovery of gas rather than mine degasification. It is also the first attempt to produce from more than one coal seam in the same wellbore.
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The formation evaluation gamma ray log is a record of the variation with depth of the natural radioactivity of earth materials in a wellbore. Measurement of natural emission of gamma rays in oil and gas wells are useful because shales and sandstones typically have different gamma ray levels. Shales and clays are responsible for most natural radioactivity, so gamma ray log often is a good indicator of such rocks. In addition, the log is also used for correlation between wells, for depth correlation between open and cased holes, and for depth correlation between logging runs.
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These valves are commonly uni-directional flapper valves which open downwards such that the flow of wellbore fluids tries to push it shut, while pressure from the surface pushes it open. This means that when closed, it will isolate the reservoir fluids from the surface. Most downhole safety valves are controlled hydraulically from the surface, meaning they are opened using a hydraulic connection linked directly to a well control panel. When hydraulic pressure is applied down a control line, the hydraulic pressure forces a sleeve within the valve to slide downwards.
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The remainder were too small to be observed or felt at the surface. Between December 2 and January 24, 168 seismic events with magnitude greater than 0.6 occurred within 1 km of the wellbore, at depths of 4–5 km, near the well bottom. On 8 December 2006, only 6 days after the main stimulation started on 2 December, the HDR project in Basel was suspended when an earthquake tripped a 4-level "traffic light" scheme established for halting operations in the event of unacceptable induced earthquake occurrences.
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In the United States, gas lift is used in 10% of the oil wells that have insufficient reservoir pressure to produce the well. In the petroleum industry, the process involves injecting gas through the tubing-casing annulus. Injected gas aerates the fluid to reduce its density; the formation pressure is then able to lift the oil column and forces the fluid out of the wellbore. Gas may be injected continuously or intermittently, depending on the producing characteristics of the well and the arrangement of the gas-lift equipment.
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This will cause pressurized fluid in the formation to flow into the wellbore and make its way to the surface. This is referred to as a formation "kick" and can lead to a potentially deadly blowout if the invading fluid reaches the surface uncontrolled. Other important mud properties to be maintained are the YP (Yield Point) which determines the carrying capacity of the mud to carry the drill cuttings to the surface. Mud should be capable of forming a thin "mud cake" which forms a lining of the borehole walls.
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The well confirmed the eastern extension of the field and also the hydrocarbon contacts seen in both sand formations in the initial discovery. A full suite of modern log and pressure data was acquired and the well was successfully tested. Following completion of testing operations, a second appraisal well Okoro 3 ST was drilled in December 2006. The well was drilled as a deviated sidetrack from the Okoro-3 wellbore and was designed to further evaluate both reservoirs and provide greater control for planning future horizontal production wells.
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Production tubing is run into the drilled well after the casing is run and cemented in place. Production tubing protects wellbore casing from wear, tear, corrosion, and deposition of by- products, such as sand / silt, paraffins, and asphaltenes. Along with other components that constitute the production string, it provides a continuous bore from the production zone to the wellhead through which oil and gas can be produced. It is usually between five and ten centimeters in diameter and is held inside the casing through the use of expandable packing devices.
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The pumps are typically electrically powered, referred to as Electrical Submersible Pumps (ESP) or if hydraulically powered, referred to as Hydraulic Submersible Pumps, (HSP). ESP systems consist of both surface components (housed in the production facility, for example an oil platform) and sub-surface components (found in the well hole). Surface components include the motor controller (often a variable speed controller), surface cables and transformers. The subsurface components are deployed by attaching to the downhole end of a tubing string, while at the surface, and then lowered into the wellbore along with the tubing.
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Since ancient times, when there were the first coal mines, it was observed, that increasing the depth of the development the coal tunnel, under the action of overburden pressure, surrounding rocks become harder and little-permeable. To solve this problem they developed a cavern of a certain form in the rock. More modern mining geo- mechanics explain the reason for the occurrence of this effect in relation to drilling wells. During any drilling process in the well there is formed the annular compressive stress conditions around the wellbore zone.
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Under the action of stress conditions and high overburden pressure occurs a significant reduction in permeability in the near wellbore zone, in some cases close to zero. Oil or gas flow can not penetrate to the well. Traditional methods of opening the productive layer formation (cumulative, jet perforation, sand jet perforation, abrasive jetting perforation and other similar methods) did not consider this complicated situation in the near-well zone and therefore was not the effective. Porous and fractured formations are subjected to compression, that deforms the rock mass and reduces its permeability.
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Rams, or ram blocks, are of four common types: pipe, blind, shear, and blind shear. Pipe rams close around a drill pipe, restricting flow in the annulus (ring-shaped space between concentric objects) between the outside of the drill pipe and the wellbore, but do not obstruct flow within the drill pipe. Variable-bore pipe rams can accommodate tubing in a wider range of outside diameters than standard pipe rams, but typically with some loss of pressure capacity and longevity. Pipe ram should not be closed if there is no pipe in the hole.
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As the piston rises, vertical movement of the packing unit is restricted by the head and the sloped face of the piston squeezes the packing unit inward, toward the center of the wellbore. In 1972, Ado N. Vujasinovic was awarded a patent for a variation on the annular preventer known as a spherical blowout preventer, so-named because of its spherical-faced head. As the piston rises the packing unit is thrust upward against the curved head, which constricts the packing unit inward. Both types of annular preventer are in common use.
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It is called biogenic sulfide corrosion. In 2011 it was reported that increased concentration of , possibly due to oil field practices, was observed in the Bakken formation crude and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements". Besides living near a gas and oil drilling operations, ordinary citizens can be exposed to hydrogen sulfide by being near waste water treatment facilities, landfills and farms with manure storage. Exposure occurs through breathing contaminated air or drinking contaminated water.
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There are several different forms of the technology, with the two main ones being Cyclic Steam Stimulation and Steam Flooding. Both are most commonly applied to oil reservoirs, which are relatively shallow and which contain crude oils which are very viscous at the temperature of the native underground formation. Steam injection is widely used in the San Joaquin Valley of California (US), the Lake Maracaibo area of Venezuela, and the oil sands of northern Alberta (Canada). Another contributing factor that enhances oil production during steam injection is related to near-wellbore cleanup.
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Production is also enhanced by artificially fracturing the rock, to allow oil to seep to the oil well. Hydrogen sulfide (H2S, also known as sour gas) is found to varying degrees in crude petroleum. The gas is flammable, corrosive, poisonous, and explosive; thus, oil with higher levels of H2S presents challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements." Bakken oil has historically been characterized as "sweet", meaning that it has little or no H2S.
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In a June 21, 2016, decision, Skavdahl held that Congress did not authorize the Bureau of Land Management to regulate hydraulic fracturing. The BLM's "Oil and Gas; Hydraulic Fracturing on Federal and Indian Lands; Final Rule" (43 CFR Part 3160) sought to set standards for wellbore construction, chemical disclosure, and water management for hydraulic fracturing on federal and tribal lands. He rejected the BLM's reliance on longstanding land management statutes as authorizing the rule. Instead, he looked to the statute that regulated hydraulic fracturing in its 2005 Energy Policy Act.
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In cased hole completions, perforations are intended to create a hole through the steel casing so that the reservoir can be produced. The holes are typically formed by shaped explosives that perforate the casing and create a fractured hole into the reservoir rock for a short distance. In many cases, the tunnels created by the perforation guns do not provide enough surface area and it becomes desirable to create more area in contact with the wellbore. In some cases, more area is needed if the reservoir is of low permeability.
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The well cannot then flow at a rate sufficient to make production economic. In this case, extending a hydraulic fracture deeper into the reservoir will allow higher production rates to be achieved. Hydraulic fracturing is performed by injecting high pressure fluids into the wellbore and into the perforation tunnels to cause the rock formation to fracture. This can either be done by injecting hydraulic fluid from surface, a process called hydraulic fracturing or using an explosive to generate a high speed gas flow, a process called propellant stimulation.
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Shut-in drill pipe pressure (SIDPP), which is recorded when a well is shut in on a kick, is a measure of the difference between the pressure at the bottom of the hole and the hydrostatic pressure (HSP) in the drillpipe. During a well shut-in, the pressure of the wellbore stabilizes, and the formation pressure equals the pressure at the bottom of the hole. The drillpipe at this time should be full of known-density fluid. Therefore, the formation pressure can be easily calculated using the SIDPP.
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Ixtoc I oil well blowout Kick is the entry of formation fluid into the wellbore during drilling operations. It occurs because the pressure exerted by the column of drilling fluid is not great enough to overcome the pressure exerted by the fluids in the formation drilled. The whole essence of oil well control is to prevent kick from occurring and if it happens to prevent it from developing into blowout. An uncontrolled kick usually results from not deploying the proper equipment, using poor practices, or a lack of training of the rig crews.
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Remotely operated underwater vehicles (ROVs) would be dispatched to inspect the condition of the wellhead, Blowout Preventer (BOP) and other subsea well equipment. The debris removal process would begin immediately to provide clear access for a capping stack. Once lowered and latched on the wellhead, a capping stack uses stored hydraulic pressure to close a hydraulic ram and stop the flow of hydrocarbons. If shutting in the well could introduce unstable geological conditions in the wellbore, a cap and flow procedure would be used to contain hydrocarbons and safely transport them to a surface vessel.
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Most rolling cutter and fixed cutter drill bits have internal passages to direct drilling fluid, conveyed by the drill pipe from surface pumps, through hydraulic nozzles directed at the bottom of the wellbore to produce high velocity fluid jets that assist in cleaning the old cuttings off the bottom before the next tooth contacts the rock. Placement of the nozzles, particularly in rolling cutter bits, is also often done to assist in keeping the cutting elements free of cuttings build-up in certain kinds of clay and shale formations.
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However, the 1974 Health & Safety at Work Act requires that measures are taken to ensure that the uncontrolled release of wellbore fluids is prevented even in the worst case. The brilliance of the act is that it does not issue prescriptive guideline for how to achieve the goal of health and safety, but merely sets out the requirement that the goal be achieved. It is up to the oil companies to decide how to achieve it and DHSVs are an important component of that decision. As such, although not a legal requirement, it is company policy for many operators in the UKCS.
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While the DHSV isolates the production tubing, a loss of integrity could allow wellbore fluid to bypass the valve and escape to surface through the annulus. For wells using gas lift, it may be a requirement to install a safety valve in the 'A' annulus of the well to ensure that the surface is protected from a loss of annulus containment. However, these valves are not as common and they are not necessarily installed at the same position in the well, meaning it is possible that fluids could snake their way around the valves to surface.
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Karambeigia A. M., Nikazar, M., Kharrat R., A novel approach for asphaltene inhibitor modeling, Journal of Petroleum Science Technology, Vol. 34(3), (2016), pp. 274–279.1808-1814. 162\. Bayat A.E., Junin R. , Kharrat R. , and Shahab H.., Evaluation of Vapor Extraction P and its Prospect as Enhanced Oil Recovery Method, International Journal of Oil Gas and Coal Technology 06 2015, 9(4), pp. 394–421. 163\. Kor P. and Kharrat R., Prediction of the asphaltene deposition profile along a wellbore during natural production from a reservoir, Energy Sources, Part A: Recovery, Utilization, and Environmental Effect, 2016, 38, issue 19, pp 2837–2844. 164\.
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Improved electrical pumps coming onto the market may enhance the effectiveness of the technology. The same concept is also applicable to oil wells when they are at the end stage of production. In this case, the reservoir pressure drops to such a low level that it cannot lift the weight of the oil/water column to the surface. By injecting a gas (such as nitrogen) into the wellbore at a specific point, the density of the fluid column can be reduced to the point that the reservoir pressure is once again able to lift fluids to the surface.
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They were carried by the current into the section they called Canal de Cardero, unable to steer or make way with oars. At the end of the day they were able to anchor at the mouth of Loughborough Inlet (Canal de Salamanca). The Spanish ships left their anchorage at Viana on July 27, 1792, and entered what is today called Chancellor Channel, thus leaving today's Cordero Channel. When they reached Hardwicke Island they turned to the northwest, leaving Chancellor Channel for Wellbore Channel (Canal de Nuevos Remolinos), which took them to Sunderland Channel and finally Johnstone Strait.
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An oil drilling platform off the coast of Santa Barbara, CA - 6 December 2011 Offshore drilling is a mechanical process where a wellbore is drilled below the seabed. It is typically carried out in order to explore for and subsequently extract petroleum which lies in rock formations beneath the seabed. Most commonly, the term is used to describe drilling activities on the continental shelf, though the term can also be applied to drilling in lakes, inshore waters and inland seas. Offshore drilling presents environmental challenges, both offshore and onshore from the produced hydrocarbons and the materials used during the drilling operation.
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A stroke bailer functions like a 'Chinese water pump', and is used to collect unwanted solids from the wellbore. A stroke bailer is long and tubular looking, with a smaller rod that extends from the top, a hole in the bottom, and is generally around 7 meters long, but the length depends on how much barrel section is added to the bailer. The barrel 'free floats' on the stroke rod, which is attached to the wireline toolstring. The tool is usually 'spudded' into the downhole solid, then the wireline toolstring is pulled upwards, which in turn pulls the stroke up through the barrel.
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The heat from the steam reduces the viscosity of the heavy crude oil or bitumen which allows it to flow down into the lower wellbore. The steam and associated gas rise because of their low density compared to the heavy crude oil below, ensuring that steam is not produced at the lower production well, tend to rise in the steam chamber, filling the void space left by the oil. Associated gas forms, to a certain extent, an insulating heat blanket above (and around) the steam. Oil and water flow is by a countercurrent, gravity driven drainage into the lower well bore.
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Measurement and interpretation of 2 and 3 phase multiphase flow can also be achieved by using alternative flow measurement technologies such as SONAR. SONAR meters apply the principles of underwater acoustics to measure flow regimes and; can be clamped on to wellheads and flow lines to measure the bulk (mean) fluid velocity of the total mixture which is then post-processed and analyzed along with wellbore compositional information and process conditions to infer the flow rates of each individual phase. This approached can be used in various applications such as black oil, gas condensate and wet gas.
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Shut-in procedures are usually developed and practiced for every rig activity, such as drilling, tripping, logging, running tubular, performing a drill stem test, and so on. The primary purpose of a specific shut-in procedure is to minimize kick volume entering into a wellbore when a kick occurs, regardless of what phase of rig activity is occurring. However, a shut-in procedure is a company-specific procedure, and the policy of a company will dictate how a well should be shut-in. They are generally two type of Shut-in procedures which are soft shut-in or hard shut-in.
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In petroleum geology and the petrochemical sciences pertaining to oil wells, and more specifically within hydrostatics, pressure gradients refer to the gradient of vertical pressure in a column of fluid within a wellbore and are generally expressed in pounds per square inch per foot (psi/ft). This column of fluid is subject to the compound pressure gradient of the overlying fluids. The path and geometry of the column is totally irrelevant; only the vertical depth of the column has any relevance to the vertical pressure of any point within its column and the pressure gradient for any given true vertical depth.
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Well control is the technique used in oil and gas operations such as drilling, well workover and well completion for maintaining the hydrostatic pressure and formation pressure to prevent the influx of formation fluids into the wellbore. This technique involves the estimation of formation fluid pressures, the strength of the subsurface formations and the use of casing and mud density to offset those pressures in a predictable fashion. Understanding pressure and pressure relationships is important in well control. The aim of oil operations is to complete all tasks in a safe and efficient manner without detrimental environmental effects.
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Swabbing is as a result of the upward movement of pipe in a well and results in a decrease in bottom hole pressure. In some cases, the bottom hole pressure reduction can be large enough to cause the well to go underbalanced and allow formation fluids to enter the wellbore. The initial swabbing action compounded by the reduction in hydrostatic pressure (from formation fluids entering the well) can lead to a significant reduction in bottom hole pressure and a larger influx of formation fluids. Therefore, early detection of swabbing on trips is critical to minimizing the size of a kick.
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From a model developed by geologists working in the UK, the drilling pipe penetrated the overpressured limestone, causing entrainment of mud by water. Whilst pulling the drill string out of the well, there were ongoing losses of drilling mud, as demonstrated by the daily drilling reports stating "overpull increasing", "only 50% returns" and "unable to keep hole full". The loss of drilling mud and associated drop in downhole mud weight eventually resulted in a drilling kick, with over 365 barrels of fluid erupting at the Banjar Panji-1 wellhead. Blowout preventers were closed to help kill the kick, which resulted in a spike in downhole pressure within the wellbore.
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In May 2011, the government suspended Cuadrilla's hydraulic fracturing operations in their Preese Hall 1 well in Lancashire, after two small earthquakes were triggered, one of magnitude M 2.3. The largest coseismic slip caused minor deformation of the wellbore and was strong enough to be felt. The company's temporary halt was pending DECC guidance on the conclusions of a study being carried out by the British Geological Survey and Keele University, which concluded in April 2012 that the process posed a seismic risk minimal enough to allow it to proceed with stricter monitoring. Cuadrilla pointed out that a number of such small-magnitude earthquakes occur naturally each month in Britain.
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Allocation is commercial rooted in the need to distribute the costs, revenues and taxes among multiple players collaborating on field development and production of oil and gas. There are various incentives for collaboration, one is risk and cost sharing, the practice by issuing licenses for exploration and production to a partnership of oil companies. Another is the aim of improving production efficiency, by extracting from multiple land properties or multiple oil fields by shared arrangement for production, also called unitisation. Production allocation to wellbore or completion is required for Reservoir Simulation where the dynamic geological model is history matched and used for production forecasting.
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The next advance was in the modification of small gyroscopic compasses by the Sperry Corporation, which was making similar compasses for aeronautical navigation. Sperry did this under contract to Sun Oil (which was involved in a lawsuit as described above), and a spin-off company "Sperry Sun" was formed, which brand continues to this day, absorbed into Halliburton. Three components are measured at any given point in a wellbore in order to determine its position: the depth of the point along the course of the borehole (measured depth), the inclination at the point, and the magnetic azimuth at the point. These three components combined are referred to as a "survey".
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The record-depth Kola Borehole used a mud motor while drilling to achieve a depth of over . Until the 1970s, most oil wells were vertical, although lithological and mechanical imperfections cause most wells to deviate at least slightly from true vertical (see deviation survey). However, modern directional drilling technologies allow for strongly deviated wells which can, given sufficient depth and with the proper tools, actually become horizontal. This is of great value as the reservoir rocks which contain hydrocarbons are usually horizontal or nearly horizontal; a horizontal wellbore placed in a production zone has more surface area in the production zone than a vertical well, resulting in a higher production rate.
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In that way, for example, a pipe ram BOP can be converted to a blind shear ram BOP. Shear-type ram BOPs require the greatest closing force in order to cut through tubing occupying the wellbore. Boosters (auxiliary hydraulic actuators) are frequently mounted to the outer ends of a BOP's hydraulic actuators to provide additional shearing force for shear rams. If a situation arises whereby the shear rams are to be activated, it is best practice for the Driller to have the string spaced as to ensure the rams will shear the body of the drillpipe as opposed to having a tooljoint (much thicker metal) across the shear rams.
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Tripping is the complete operation of removing the drillstring from the wellbore and running it back in the hole. This operation is typically undertaken when the bit (which is the tool used to crush or cut rock during drilling) becomes dull or broken, and no longer drills the rock efficiently. A typical drilling operation of deep oil or gas wells may require up to 8 or more trips of the drill string to replace a dull rotary bit for one well. Tripping out of the hole means that the entire volume of steel (of drillstring) is being removed, or has been removed, from the well.
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A cement bond log documents the evaluation of the integrity of cement work performed on an oil well. In the process of drilling and completing a well, cement is injected through the wellbore and rises up the annulus between the steel casing and the formation. A sonic tool is typically run on wireline by a service company that detects the bond of the cement to the casing and formation via a principle based on resonance. Casing that is not bound has a higher resonant vibration than that which is bound, causing the imparted energy from the sonic signal to be transferred to the formation.
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In the oil and gas industry, a drill bit is a tool designed to produce a generally cylindrical hole (wellbore) in the earth’s crust by the rotary drilling method for the discovery and extraction of hydrocarbons such as crude oil and natural gas. This type of tool is alternately referred to as a rock bit, or simply a bit. The hole diameter produced by drill bits is quite small, from about to , compared to the depth of the hole, which can range from to more than . Subsurface formations are broken apart mechanically by cutting elements of the bit by scraping, grinding or localized compressive fracturing.
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Hydraulic fracturing, also called fracking, fracing, hydrofracking, fraccing, frac'ing, and hydrofracturing, is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of 'fracking fluid' (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950.
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A hydraulic fracture is formed by pumping fracturing fluid into a wellbore at a rate sufficient to increase pressure at the target depth (determined by the location of the well casing perforations), to exceed that of the fracture gradient (pressure gradient) of the rock. The fracture gradient is defined as pressure increase per unit of depth relative to density, and is usually measured in pounds per square inch, per square foot, or bars. The rock cracks, and the fracture fluid permeates the rock extending the crack further, and further, and so on. Fractures are localized as pressure drops off with the rate of frictional loss, which is relative to the distance from the well.
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For both low and high volume hydraulic fracturing stimulation of a hydrocarbon well, a high-pressure fluid (usually water) containing chemical additives and a proppant is injected into a wellbore to create an extensive system of small cracks in the deep-rock formations. These cracks provide the pathway for: natural gas, (including shale gas, tight gas and coalbed methane); petroleum, (including shale or tight oil); to flow more freely. When the hydraulic pressure is removed from the well, the small grains of hydraulic fracturing proppant hold the fractures open when the pressure is released. When a hydrocarbon well is hydraulically fractured, this is done through a production packer (seal), through the drill pipe or tubing.
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Although hydraulic fracturing is often used synonymously to refer to shale gas and other unconventional oil and gas sources, it is not always correct to associate it with unconventional gas. In late May 2011, the first UK exploration for shale gas using high-volume hydraulic fracturing was suspended at Preese Hall at Weeton in Lancashire after the process triggered two minor earthquakes. The larger of the earthquakes caused minor deformation of the wellbore and was strong enough to be felt. The report of 2012 by the Royal Society and the Royal Academy of Engineering concluded that earthquake risk was minimal, and recommended the process be given nationwide clearance, although it highlighted certain concerns which led to changes in regulations.
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Drilling fluid invasion is a process that occurs in a well being drilled with higher wellbore pressure (normally caused by excessive mud weights) than formation pressure. The liquid component of the drilling fluid (known as the mud filtrate, or spurt) continues to "invade" the porous and permeable formation until the solids present in the mud, commonly bentonite, clog enough pores to form a mud cake capable of preventing further invasion. If invasion is severe enough, and reservoir pressures are unable to force the fluid and associated particles out entirely when the well starts producing, the amount of oil and gas a well can produce can be permanently reduced. This is especially true when a process called phase trapping occurs.
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Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived as arcane. The next major advance was in the 1970s, when downhole drilling motors (aka mud motors, driven by the hydraulic power of drilling mud circulated down the drill string) became common. These allowed the drill bit to continue rotating at the cutting face at the bottom of the hole, while most of the drill pipe was held stationary. A piece of bent pipe (a "bent sub") between the stationary drill pipe and the top of the motor allowed the direction of the wellbore to be changed without needing to pull all the drill pipe out and place another whipstock.
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A well is plugged by placing cement in the well-bore or casing at certain intervals as specified in California laws or regulations. The purpose of the cement is to seal the wellbore or casing and prevent fluid from migrating between underground rock layers. Cement plugs are required to be placed across the oil or gas reservoir (zone plug), across the base-of-fresh- water (BFW plug), and at the surface (surface plug). Other cement plugs may be required at the bottom of a string of open casing (shoe plug), on top of tools that may become stuck down hole (junk plug), on top of cut casing (stub plug), or anywhere else where a cement plug may be needed.
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If the rock is characterized by low-permeability – which refers to its ability to let substances, i.e. gas, pass through it, then the rock may be considered a source of tight gas. Fracking for shale gas, which is currently also known as a source of unconventional gas, involves drilling a borehole vertically until it reaches a lateral shale rock formation, at which point the drill turns to follow the rock for hundreds or thousands of feet horizontally. In contrast, conventional oil and gas sources are characterized by higher rock permeability, which naturally enables the flow of oil or gas into the wellbore with less intensive hydraulic fracturing techniques than the production of tight gas has required.
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The advantages of this technology are many for both main groups of users: geoscientists and drillers. Continuous rotation of the drill string allows for improved transportation of drilled cuttings to the surface resulting in better hydraulic performance, better weight transfer for the same reason allows a more complex bore to be drilled, and reduced well bore tortuosity due to utilizing a more steady steering model. The well geometry therefore is less aggressive and the wellbore (wall of the well) is smoother than those drilled with a motor. This last benefit concerns geoscientists, because better measurements of the properties of the formation can be obtained, and the drillers, because the well casing or production string can be more easily run to the bottom of the hole.
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Slot length is equal to the length of the working engine shaft, usually . The hydro-slotting perforation process does not deform the casing, does not create cracks in the cement, and does not clog-up the borders in the formation. The geometry and depth of the slots creates the conditions for occurrence of the effect of unloading the circular stress conditions in the near wellbore zone (from 50 to 100 percent) and accordingly the increase of permeability (up to 30 to 50 percent) in this zone. In addition to this it forms a large area of the penetration ( area for one cut with two nozzles only), that provides a very good hydrodynamic connection of the productive layer with the well.
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It has steel blades to shear the pipe and seals to seal the annulus after shearing the pipe. Blind shear rams (also known as shear seal rams, or sealing shear rams) are intended to seal a wellbore, even when the bore is occupied by a drill string, by cutting through the drill string as the rams close off the well. The upper portion of the severed drill string is freed from the ram, while the lower portion may be crimped and the “fish tail” captured to hang the drill string off the BOP. In addition to the standard ram functions, variable-bore pipe rams are frequently used as test rams in a modified blowout preventer device known as a stack test valve.
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Devices fitted with hinged collars and bow springs help keep the casing or liner in the center of the wellbore to help ensure efficient placement of a cement sheath around the casing string. If casing strings are cemented off-center, there is a high risk that a channel of drilling fluid or contaminated cement will be left where the casing contacts the formation, creating an imperfect seal. Turbolizers have added fins to "stir" up the drilling fluid and cement to keep the flow turbulent in order to make sure the cement flows all the way around the casing in order to prevent channeling. Scratchers use metal wires to scrape mud cake off permeable zones to help obtain a solid cement column.
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In this case, these microfractures are analogous to Griffith Cracks, however they can often be sufficient to supply the necessary productivity, especially after completions, to make what used to be marginally economic zones commercially productive with repeatable success. However, while natural fractures can often be beneficial, they can also act as potential hazards while drilling wells. Natural fractures can have very high permeability, and as a result, any differences in hydrostatic balance down the well can result in well control issues. If a higher pressured natural fracture system is encountered, the rapid rate at which formation fluid can flow into the wellbore can cause the situation to rapidly escalate into a blowout, either at surface or in a higher subsurface formation.
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The drilling-induced triggering model proposes that the increase in pressure within the wellbore was sufficiently high to induce a large hydraulic fracture in the formation. The extra pressure caused the hydraulic fractures to propagate 1–2 km to the surface and emerged 200 m away from the well. The lack of protective casing in the bottom 1742m of the borehole is considered a key reason why the drilling kick could not be controlled and why pressures during the kick were high enough to initiate hydraulic fracturing. Alternatively, it has also been suggested that the increased fluid pressure in the borehole, due to the kick, may have triggered reactivation of a nearby fault system, rather than hydraulic fracturing (in a similar manner to how fluid injection can induce seismicity).
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Bloomberg report NP 13 August The academic community commented in 2011 that increased concentration of H2S was observed in the field and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements".Holubnyak et al, SPE 141434-MS Holubnyak et al. write, further, that Bakken crude "may become soured through current oil field practices". At issue in the Lac-Mégantic derailment, then, is whether World Fuel Services and other defendants ought to have been aware of this two-year-old research when they ordered the DOT-111 tank cars (which were already in 2012 acknowledged by the US NTSB regulator to be deficient for these purposes) to be loaded on the Lac-Mégantic train.
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Forward Harbour was a cannery town in the Johnstone Strait region of the Central Coast of British Columbia, Canada, located on the inlet of the same name, which is on the mainland side of Wellbore Channel, to the east of Hardwicke Island. Nearby on the same vicinity on the Mainland, though fronting on other bodies of water, are Jackson Bay to the immediate north, off Sunderland Channel, and Heydon Bay, British Columbia to the east on Loughborough Inlet. Forward Harbour was named in 1865 for HMS Forward (1855), a Royal Navy gunboat commanded by Lieutenant Horace Douglas Lascelles. Names in Forward Harbour were all in honour of the Lascelles family, particularly Florence and Cust Points, which honour Lady Florence Cust, daughter of the 3rd Earl of Harewood and wife of Lieutenant Colonel John F. Cust.
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That is why oil well control procedures should be in place prior to the start of an abnormal situation noticed within the wellbore, and ideally when a new rig position is sited. In other words, this includes the time the new location is picked, all drilling, completion, workover, snubbing and any other drilling-related operations that should be executed with proper oil well control in mind. This type of preparation involves widespread training of personnel, the development of strict operational guidelines and the design of drilling programs – maximizing the probability of successfully regaining hydrostatic control of a well after a significant influx of formation fluid has taken place.Karen Bybee, "A Well-Specific Approach to the Quantification of Well Control", Society of Petroleum Engineers, Journal of Petroleum Technology (JPT), archived 2010/01/15, p.60.
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A new technology has recently been developed which combines gas lift with a rod pump, dedicating two separate tubing strings in the wellbore for each lift method. This technique is designed specifically to artificially lift the unique geometry of horizontal/deviated wells and also vertical wells that have deep or very long perforated intervals, or have too high of a gas liquid ratio (GLR) for conventional artificial lift methods. In this design, the rod pump is placed in the vertical portion of the well above the deviated or perforated interval, while relatively low pressure-low volume gas is used to lift reservoir liquids from the deviated or extended perforated interval to above the rod pump. Once the liquids are raised above the pump, they become trapped above a packer and then enter the pump chamber where they are transported to the surface.
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Which of the doctrines applies in a particular case depends on state law, which varies considerably from state to state, or in the case of the federal offshore zone, on U.S. federal law. The rule of capture provides that an oil producer with a wellbore on his property is allowed to drain oil out from underneath his land—even if some of that oil originated from a neighbor's land, migrating to the oil producer's land through geologic forces or drainage. The rule of capture gives landowners an incentive to pump out oil as quickly as possible by accelerating operations or drilling multiple wells to capture the oil of their neighbors. Such practice may deplete the gas pressure needed to force oil from the ground, which will reduce the amount of oil available for recovery from that reservoir.
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The Montara oil spill was an oil and gas leak and subsequent slick that took place in the Montara oil field in the Timor Sea, off the northern coast of Western Australia. It is considered one of Australia's worst oil disasters. The slick was released following a blowout from the Montara wellhead platform on 21 August 2009, and continued leaking until 3 November 2009 (in total 75 days), when the leak was stopped by pumping mud into the well and the wellbore cemented thus "capping" the blowout. The West Atlas rig is owned by the Norwegian-Bermudan Seadrill, and operated by PTTEP Australasia (PTTEPAA), a subsidiary of PTT Exploration and Production (PTTEP) which is in turn a subsidiary of PTT, the Thai state-owned oil and gas company was operating over on adjacent well on the Montara platform.
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Geosteering only practically became possible with the advent of deep reading 2 MHz resistivity LWD tools from the major LWD vendors (BakerHughes Reservoir Navigation Tool, SperrySun and Schlumberger) and other tools in the early 1990s, and the forward modeling software from a number of vendors capable of predicting resistivity tool responses for different relative angles and formation resistivities. Prior to this, Gamma ray gave some bed information, but was rarely used to dynamically adjust the well path in relation to the best oil saturation and porosity. The advent of nuclear tools for porosity and azimuthally sensitive gamma and resistivity tools, improved the ability to infer whether the wellbore should be steered up or down. The development of the Troll Oilfield by Norsk Hydro (Later Statoil and Equinor) would not have been possible without the ability to precisely geosteer within a 4-meter thick horizon to avoid gas above and water below.
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Raj Chellaraj is the CFO and Senior Associate Dean for Finance and Administration, Graduate School of Business, Stanford University. Concurrently, he was also the Chief Operating Officer at the Stanford Institute for Innovation in Developing Economies (Stanford Seed) with primary focus in Africa and India from 2015 to 2017.. He is the former Assistant Secretary of State for Administration at the United States Department of State from 2006 to 2009 under Secretary of State Condoleezza Rice.. Currently, he serves on the Board of Wellbore Integrity Solutions, a global oilfield services provider, a portfolio company of private equity firm Rhône Group. In addition, he is an advisor and consultant to United Nations (UNICEF) leadership in operations and management. Previously, he served on the board of GardaWorld from 2017-19, a company that provides protective services around the world, aviation services in Canada, and cash in transit and vaults in North America.
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The US government report issued in September 2011 stated that BP is ultimately responsible for the spill, and that Halliburton and Transocean share some of the blame. The report states that the main cause was the defective cement job, and Halliburton, BP and Transocean were, in different ways, responsible for the accident. The report stated that, although the events leading to the sinking of Deepwater Horizon were set into motion by the failure to prevent a well blowout, the investigation revealed numerous systems deficiencies, and acts and omissions by Transocean and its Deepwater Horizon crew, that had an adverse impact on the ability to prevent or limit the magnitude of the disaster. The report also states that a central cause of the blowout was failure of a cement barrier allowing hydrocarbons to flow up the wellbore, through the riser and onto the rig, resulting in the blowout.
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The report concluded that the primary cause of failure was that the blind shear rams failed to fully close and seal due to a portion of drill pipe trapped between the shearing blocks. This happened because the drill pipe elastically buckled within the wellbore due to forces induced on the drill pipe during loss of well control, consequently, drill pipe in process of shearing was deformed outside the shearing blade surfaces, and, consequently, the blind shearing rams were not able to move the entire pipe cross section into the shearing surfaces of the blades. Therefore, oil continued to flow through the drill pipe trapped between the ram block faces and subsequently through the gaps between the ram blocks. Since the pipe buckled when well control was lost, the blind shear rams would have failed to function as planned no matter when they were made active.
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A drilling rig is used to create a borehole or well (also called a wellbore) in the earth's sub-surface, for example in order to extract natural resources such as gas or oil. During such drilling, data is acquired from the drilling rig sensors for a range of purposes such as: decision-support to monitor and manage the smooth operation of drilling; to make detailed records (or well log) of the geologic formations penetrated by a borehole; to generate operations statistics and performance benchmarks such that improvements can be identified, and to provide well planners with accurate historical operations- performance data with which to perform statistical risk analysis for future well operations. The terms measurement while drilling (MWD), and logging while drilling (LWD) are not used consistently throughout the industry. Although these terms are related, within the context of this section, the term MWD refers to directional-drilling measurements, e.g.
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Oilfield Surface Resonant Vibrator The concept of using vibration to free stuck objects from a wellbore originated in the 1940s, and probably stemmed from the 1930s use of vibration to drive piling in the Soviet Union. The early use of vibration for driving and extracting piles was confined to low frequency operation; that is, frequencies less than the fundamental resonant frequency of the system and consequently, although effective, the process was only an improvement on conventional hammer equipment. Early patents and teaching attempted to explain the process and mechanism involved, but lacked a certain degree of sophistication. In 1961, A. G. Bodine obtained Patent number: 2972380, Filing date: Feb 20, 1956, Issue date: Feb 1961, Inventor: Albert G. Bodine Title: "Acoustic Method and Apparatus For Moving Objects Held Tight Within a Surrounding Medium" that was to become the "mother patent" for oil field tubular extraction using sonic techniques.
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Hydraulic pumping systems transmit energy to the bottom of the well by means of pressurized power fluid that flows down in the wellbore tubular to a subsurface pump. There are at least three types of hydraulic subsurface pump: #a reciprocating piston pump, where one side is powered by the (injected) drive fluid while the other side pumps the produced fluids to surface #a jet pump, where the (injected) drive fluid passes through a nozzle-throat venturi combination, mixes with produced fluids and by the venturi effect creates a high pressure at the discharge side of the pump. #a hydraulically driven downhole turbine (HSP), whereby the downhole drive motor is a turbine, mechanically connected to the impeller-pump section which pumps the fluid. These systems are very versatile and have been used in shallow depths (1,000 ft) to deeper wells (18,000 ft), low rate wells with production in the tens of barrels per day to wells producing in excess of 20,000 bbl (3,200 m3) per day.
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Heavy-weight drill string part due to stress cracking Tripping pipe (or "Making a round trip" or simply "Making a trip") is the physical act of pulling the drill string out of the wellbore and then running it back in. This is done by physically breaking out or disconnecting (when pulling out of the hole) every other 2 or 3 joints of drill pipe at a time (called a stand) and racking them vertically in the derrick. When feasible the driller will start each successive trip on a different "break" so that after several trips fresh pipe dope will have been applied (when running back in the hole) to every segment of the drill string. Pulling Pipe on the Derrick Floor preparing to trip into the hole Collection of 90 foot stands after tripping out of the hole for a bit trip The most typical reason for tripping pipe is to replace a worn- out drill bit.
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Seismic -Geostatistical Reservoir Modeling Using Collocated Cokriging Method (A Case Study in South Pars Gas Field), M. Tavakolo, 2010. 121\. Investigation of Parameters Affecting Nanoparticle Flooding, A. Heydariyan, 2012. 122\. Analysis of parameters affecting VAPEX process in fractured reservoirs, H. Pendar, 2012. 123\. Optimization of water – flooding projects using harmony search algorithm, M. Khalili 2012. 124\. Experimental study of pressure temperature and salinity Impact on stability of Nano-particles emulsion and their impact on water flooding performance, J. Esmaeli, 2012. 125\. Investigation of reservoir parameter on GAGD process for naturally fractured reservoir, E. Mesagh, 2013. 126\. Experimental study of effect of utilizing polymer agents to stabilize nanoparticle solutions for EOR purposes, R. Elhei, 2013. 127\. Asphaltene phase Envelope (APE) development using artificial neural network and fuzzy logic based on experimental data, M. Mohamedi, 2013. 128\. Investigating the Dynamic Phase Behavior of Asphaltene in Wellbore, A. Ayoobi, 2013. 129\. Experimental investigation of Asphaltene inhibitors for an Iranian oil field (South western region, Madhi M, 2013. 130\.
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Proven oil reserves, 2013 Total possible conventional crude oil reserves include crude oil with 90% certainty of being technically able to be produced from reservoirs (through a wellbore using primary, secondary, improved, enhanced, or tertiary methods); all crude with a 50% probability of being produced in the future (probable); and discovered reserves that have a 10% possibility of being produced in the future (possible). Reserve estimates based on these are referred to as 1P, proven (at least 90% probability); 2P, proven and probable (at least 50% probability); and 3P, proven, probable and possible (at least 10% probability), respectively. This does not include liquids extracted from mined solids or gasses (oil sands, oil shale, gas-to- liquid processes, or coal-to-liquid processes). Hubbert's 1956 peak projection for the United States depended on geological estimates of ultimate recoverable oil resources, but starting in his 1962 publication, he concluded that ultimate oil recovery was an output of his mathematical analysis, rather than an assumption.
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NETL helps advance development of technologies supporting efficient, environmentally benign unconventional domestic oil and gas resources. The Lab's research projects help catalyze the development of these new technologies, provide objective data to help quantify the environmental and safety risks of oil and gas development, and characterize emerging energy resources like methane hydrate or shale gas production. The program foci are on deepwater technology, enhanced oil recovery, and methane hydrate. NETL's research on unconventional oil and gas includes efforts for improving wellbore cement used to stabilize wells for deepwater drilling; expeditions to determine presence and volume of methane hydrate along coastlines; development of hydraulic fracturing data collection tools to improve environmental reporting, monitoring, and protection; analysis to determine alternate sources of freshwater for oil and gas development, as well as many other areas of expertise. Natural gas and oil resources supply two-thirds of the United States’ primary energy supply, and researching their development allows for their continued use as efforts toward transition to a more sustainable energy future are made.
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This summary is based largely on the summary provided by the Congressional Research Service, a public domain source. The Protecting States' Rights to Promote American Energy Security Act would amend the Mineral Leasing Act of 1920 to prohibit the United States Department of the Interior from enforcing any federal regulation, guidance, or permit requirement regarding hydraulic fracturing (including any component of that process), relating to oil, gas, or geothermal production activities on or under any land in any state that has regulations, guidance, or permit requirements for that activity. The bill would require the Department to recognize and defer to state regulations, permitting, and guidance, for all activities related to hydraulic fracturing relating to oil, gas, or geothermal production activities on federal land regardless of whether those rules are duplicative, more or less restrictive, have different requirements, or do not meet federal guidelines. The bill defines "hydraulic fracturing" as the process by which fracturing fluids (including a fracturing fluid system) are pumped into an underground geologic formation to generate fractures or cracks, thereby increasing rock permeability near the wellbore and improving production of natural gas or oil.
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Rig Technologies engineers and manufactures drilling rigs, advanced drilling equipment packages, and the related capital equipment (including top drives, iron roughnecks, drawworks, blowout preventers, mud pumps, risers, pipe handling, power and control systems) necessary to drill oil and gas wells, as well as marine construction equipment such as heavy-lift cranes, mooring machinery, jacking systems, pipelay and cablelay systems, and marine riser tensioners. In addition, the segment provides aftermarket equipment and services such as spare parts, repair, and equipment rentals as well as remote equipment monitoring, technical support, field service, and customer training. Wellbore Technologies develops the equipment, technologies, and services necessary to maximize the efficiency and economics of oil and gas wells. The segment provides the oil and gas industry with drill bits, borehole enlargement services, and directional drilling tools and optimization/automation software and services; downhole tools for drilling and intervention; premium drill pipe and drill stem accessories; solids control and waste management equipment and services; drilling and completion fluids; data acquisition and analytics technologies; managed-pressure-drilling systems; coating and inspection services and RFID technology for drill pipe lifecycle management; and IntelliServ wired drill pipe.
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Sensitivity analysis on the VAPEX process in the heavy oil reservoir with overlying Gas Cap, R. Farkhpoor, 2007. 70\. Numerical analysis of improved parameters affecting the forces gravity drainage mechanism in conventional oil reservoir, F. Kamali, 2007. 71\. Experimental study of the hydrocarbon solvent flooding using glass type Micromodel, T. Behrouz, 2007. 72\. Investigation of analytical solution and relative permeability determination in forced gravity drainage process, S. Samani, 2007. 73\. Modeling and simulation of heavy oil recovery through the VAPEX process, A. T. Borujeni, 2007. 74\. Numerical wellbore stability modeling in hydrate bearing sediments, M. M. Saadabad, 2007. 75\. Viability study of implementing smart/intelligent completion in commingled wells in an Australian offshore oil field, M. Nadiripari, 2007. 76\. Modeling and Simulation of In-Situ Combustion in Oil Carbonate Reservoirs, M. Taghavifar, 2007. 77\. Experimental and Numerical Study of Dispersion Coefficients in Miscible Flooding of Hydrocarbon Solvent Crude Oil Using G.ASS Type Micromodel, A. Rezaeipour, 2007. 78\. Experimental Study of Surfactants/Water/Polymer Flooding Using One-Quarter Five-Spot Glass Micromodels, B. Yadali Jamaloei, 2007. 79\. Laboratory study on Precipitation of Sulphate Scales in Porous Media Using Visual Glass Micromodels, S. M. Ghaderi, 2007. 80\. Cyclic Steam Stimulation by Horizontal Well in One of Iranian Heavy Oil Reservoirs, S. D. Razavi, 2007. 81\. Consideration of PVT Properties in Simulation of Mechanism of VAPEX Method, L. Roohi, 2007. 82\.
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