The project requires advanced drilling and extraction techniques due to the variable permeabilities and porosities of the carbonate reservoirs, Gazprom Neft has said.
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When blended calcines were used, permeabilities were two to three times greater for misted than for unmisted feeds.
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The concept of permeability is of importance in determining the flow characteristics of hydrocarbons in oil and gas reservoirs, and of groundwater in aquifers Multiphase fluid flow in porous media From Transport in porous media . For a rock to be considered as an exploitable hydrocarbon reservoir without stimulation, its permeability must be greater than approximately 100 md (depending on the nature of the hydrocarbon – gas reservoirs with lower permeabilities are still exploitable because of the lower viscosity of gas with respect to oil). Rocks with permeabilities significantly lower than 100 md can form efficient seals (see petroleum geology). Unconsolidated sands may have permeabilities of over 5000 md.
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The top of the reservoir is about below sea level and the oil column extends for over . The field is in very shallow water, deep. The seal is middle Permian shale and late Permian salt. The reservoir consists of limestones with low porosities and permeabilities.
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For equal permeabilities (e.g., non-magnetic media), if and are complementary, we can substitute for and for so that the numerator in equation () becomes which is zero (by Snell's law). Hence and only the s-polarized component is reflected. This is what happens at the Brewster angle.
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The best quality reservoir in the Gulf of Suez is the mainly Lower Cretaceous Malha Formation, sometimes known as the 'Nubia' or 'Nubian A'. This pre-rift sequence is present throughout the gulf, and has porosities in the range 13–29 % with permeabilities varying from 70–400 md.
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The main reservoir in the Groningen field is the Cisuralian (Lower Permian), Rotliegend Slochteren sandstone. The Rotliegend reservoir at Groningen is mainly an aeolian sand with local development of fluvial wadi sands. Porosities lie generally in the range 15–20% with permeabilities in the range 0.1–3000 mD.
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A collaborative randomized trial from Europe, the MPO (Membrane Permeabilities Outcomes) study, comparing mortality in patients just starting dialysis using either high-flux or low-flux membranes, found a nonsignificant trend to improved survival in those using high-flux membranes, and a survival benefit in patients with lower serum albumin levels or in diabetics.
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The goal is to recover the diffusion coefficient in the parabolic partial differential equation that models single phase fluid flows in porous media. This problem has been the object of many studies since a pioneering work carried out in the early seventies. Concerning two-phase flows an important problem is to estimate the relative permeabilities and the capillary pressures.
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Sandstones may vary in permeability from less than one to over 50,000 millidarcys (md). Permeabilities are more commonly in the range of tens to hundreds of millidarcies. A rock with 25% porosity and a permeability of 1 md will not yield a significant flow of water. Such “tight” rocks are usually artificially stimulated (fractured or acidized) to create permeability and yield a flow.
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It is estimated that Bahar field holds 2.7 million tonnes of oil and between 18.4Caspian Energy. Old Offshore Oilfields of Azerbaijan and their rehabilitation and 25 billion cubic meters of gas reserves. It contains oil and gas condensate in sandstone and sandy siltstone of the Pliocene Productive Series. The reservoir rocks have porosities of 13-18% and permeabilities of 45-250 mD.
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Unlike configurations of simple permanent magnets, electrodynamic levitation can be made stable. Electrodynamic levitation with metallic conductors exhibits a form of diamagnetism, and relative permeabilities of around 0.7 can be achieved (depending on the frequency and conductor configuration). Given the details of the applicable hysteresis loop, frequency-dependent variability of behavior should be of minimal importance for those magnetic materials that are likely to be deployed.
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Silica membranes are mesoporous and can be made with high uniformity (the same structure throughout the membrane). The high porosity of these membranes gives them very high permeabilities. Synthesized membranes have smooth surfaces and can be modified on the surface to drastically improve selectivity. Functionalizing silica membrane surfaces with amine containing molecules (on the surface silanol groups) allows the membranes to separate CO2 from flue gas streams more effectively.
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While this is a reversal potential in the sense that membrane potential reverses direction, it is not an equilibrium potential because not all (and in some cases, none) of the ions are in equilibrium and thus have net fluxes across the membrane. When a cell has significant permeabilities to more than one ion, the cell potential can be calculated from the Goldman–Hodgkin–Katz equation rather than the Nernst equation.
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Membrane-based biogas upgrading systems utilize the different permeabilities of gases through a membrane fiber. As biogas passes through a dense polymeric membrane, CO2 is prevented from through-flow and removed, while CH4 passes through. Membrane-based gas permeation systems consume only electrical power, but do not require any chemicals or water. In order to achieve higher methane contents (up to 99% methane) in the final gas, the gas passes through serial groups of membranes.
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Different oils have different evaporation permeabilities, therefore yielding changes in concentration rates from different percipient/protein mixture. It is extremely difficult to predict good conditions for nucleation or growth of well-ordered crystals. In practice, favorable conditions are identified by screening; a very large batch of the molecules is prepared, and a wide variety of crystallization solutions are tested. Hundreds, even thousands, of solution conditions are generally tried before finding the successful one.
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The difficulty is that reservoirs are not uniform. They have variable porosities and permeabilities and may be compartmentalised, with fractures and faults breaking them up and complicating fluid flow. For this reason, computer modeling of economically viable reservoirs is often carried out. Geologists, geophysicists, and reservoir engineers work together to build a model that allows simulation of the flow of fluids in the reservoir, leading to an improved estimate of the recoverable resources.
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Again Muskat refined Darcy's equation by generalizing to three equations for the three space dimensions, as pointed out earlier by Philipp Forchheimer.Forchheimer P. 1914; Hydraulik; Book published by B.G. Teubner, Leipzig und Berlin, 1914, p 437. The single- phase permeability was generalized to be a 3x3 tensor which is usually represented by a diagonal tensor where the vertical permeability differ from the two horizontal permeabilities. In 1937 Muskat published The Flow of Homogeneous Fluids Through Porous Media.
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A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings. The surroundings may include other thermodynamic systems, or physical systems that are not thermodynamic systems. A wall of a thermodynamic system may be purely notional, when it is described as being 'permeable' to all matter, all radiation, and all forces. A widely used distinction is between isolated, closed, and open thermodynamic systems.
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The existing groundwater aquifers and their annual recharge rate have not been adequately quantified. In a general sense, groundwater is available throughout the less mountainous areas of Belize and favourable yield can be attributed to geology and climatic conditions. The northern region consists of calcareous sediments that have shown high permeabilities. In the South where limestones are found similar groundwater yield conditions are indicated, while the shales and slates have poor permeability and therefore have low capacity for groundwater extraction.
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Water injection helps maintain downhole pressure so that oil can continue to flow. Water from the injection well is also used to sweep or push the oil towards the producing wells. But rock in the reservoir has varying permeabilities; the more permeable the rock is, the more easily the fluid can flow through. Water takes the path of least resistance when pumped into the ground Unfortunately, water flows more readily than oil, and it always takes the path of least resistance.
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The structure comprises a series of southwesterly dipping tilted fault blocks. The reservoir sandstones are Middle Jurassic in age and were deposited as a result of deltaic progradation across the Hutton area. The oil bearing Brent Group sandstones vary in thickness from 150 ft to 380 ft with average porosities of 22% and permeabilities of 500-2000 md in the producing zones. Original recoverable reserves were estimated at 190 million barrels, of which the field has produced 107 million barrels by 1991.
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Guggenheim, E.A. (1949). Statistical basis of thermodynamics, Research: A Journal of Science and its Applications, 2, Butterworths, London, pp. 450–454. In equilibrium thermodynamics, the state of a thermodynamic system is a state of thermodynamic equilibrium, as opposed to a non- equilibrium state. According to the permeabilities of the walls of a system, transfers of energy and matter occur between it and its surroundings, which are assumed to be unchanging over time, until a state of thermodynamic equilibrium is attained.
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A diagram of a generic thermodynamic system An important concept in thermodynamics is the thermodynamic system, which is a precisely defined region of the universe under study. Everything in the universe except the system is called the surroundings. A system is separated from the remainder of the universe by a boundary which may be a physical or notional, but serve to confine the system to a finite volume. Segments of the boundary are often described as walls; they have respective defined 'permeabilities'.
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Ali Sharif, Tight gas resources in Western Australia, Western Australia Department of Mines and Petroleum, Sept. 2007. Although shales have low permeability and low effective porosity, shale gas is usually considered separate from tight gas, which is contained most commonly in sandstone, but sometimes in limestone. Tight gas is considered an unconventional source of natural gas. Rock with permeabilities as little as one nanodarcy, reservoir stimulation may be economically productive with optimized spacing and completion of staged fractures to maximize yield concerning cost.
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Structure of eukaryotic voltage-gated potassium ion channels Excitable cells in living organisms have voltage-gated ion channels. These can be observed throughout the nervous system in neurons. The first ion channels to be characterized were the sodium and potassium ion channels by A.L. Hodgkin and A.F. Huxley in the 1950s upon studying the giant axon of the squid genus Loligo. Their research demonstrated the selective permeability of cellular membranes, dependent on physiological conditions, and the electrical effects that result from these permeabilities to produce action potentials.
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Or it may be homogeneous. Such systems may be regarded as 'simple'. A 'compound' thermodynamic system may comprise several simple thermodynamic sub-systems, mutually separated by one or several walls of definite respective permeabilities. It is often convenient to consider such a compound system initially isolated in a state of thermodynamic equilibrium, then affected by a thermodynamic operation of increase of some inter-sub-system wall permeability, to initiate a transient thermodynamic process, so as to generate a final new state of thermodynamic equilibrium.
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The biochemical properties and channel permeabilities of these more complex channels differ from homotypic Cx30 or Cx26 channels. Overexpression of Cx30 in Cx30 null mice restored Cx26 expression and normal gap junction channel functioning and calcium signaling, but it is described that Cx26 expression is altered in Cx30 null mice. The researchers hypothesized that co-regulation of Cx26 and Cx30 is dependent on phospholipase C signaling and the NF-κB pathway. The cochlea contains two cell types, auditory hair cells for mechanotransduction and supporting cells.
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One could predict reflection coefficients that agreed with observation by supposing (like Fresnel) that different refractive indices were due to different densities and that the vibrations were normal to what was then called the plane of polarization, or by supposing (like MacCullagh and Neumann) that different refractive indices were due to different elasticities and that the vibrations were parallel to that plane.Whittaker, 1910, pp.133,148–9; Darrigol, 2012, pp.212,229–31. Thus the condition of equal permittivities and unequal permeabilities, although not realistic, is of some historical interest.
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Its permeability can range from 14 to 550. (See permeabilities of common materials.) Toroidal powder cores are used in the development of a subgroup of microelectronics known as inductors, transformers and electronic filters. An MPP core possesses many positive magnetic qualities which makes it more optimal to use in the creation of such devices. A few of its properties include: low eddy current losses and hysteresis, low permeability changes in high temperatures, high Curie temperature, high electrical resistivity at operating frequency and exemplary inductive stability under both AC and DC currents.
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The subsequent change in stimulation threshold of the postsynaptic membrane can be enhanced or inhibited, depending on the transmitter chemical involved and the ion permeabilities. Thus the synapse acts as a decision point at which information converges, and it is modified by algebraic processing of EPSPs and IPSPs. In addition to the IPSP inhibitory mechanism, there is a presynaptic kind of inhibition that involves either a hyperpolarization on the inhibited axon or a persistent depolarization; whether it is the former or the latter depends on the specific neurons involved.
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From equations () and (), we see that two dissimilar media will have the same refractive index, but different admittances, if the ratio of their permeabilities is the inverse of the ratio of their permittivities. In that unusual situation we have (that is, the transmitted ray is undeviated), so that the cosines in equations (), (), (), (), and () to () cancel out, and all the reflection and transmission ratios become independent of the angle of incidence; in other words, the ratios for normal incidence become applicable to all angles of incidence.. When extended to spherical reflection or scattering, this results in the Kerker effect for Mie_Scattering.
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The Bentley Field, located on the UK continental shelf in block 9/3b in 110 m of water, contains approximately in-place of heavy (10 to 12 oAPI) viscous (1500 cP) crude. The field is four-way dip closed at uppermost Palaeocene, lowermost Eocene, Dornoch sandstone level, and covers an area of about 16 km by 5 km at a depth of around 1.1 km TVDss. The reservoir is high porosity (33%), net to gross pay (90%) and with ultra-high apparent horizontal permeabilities approaching 50 Darcies based on flow-test measurements, but consistent with unconsolidated sand.
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There is a progressive transition in the depositional environment from subaqueous fans, through fan deltas and shoreface to delta plain. The uppermost Tarbert formation may represent reworked delta plain deposits at the onset of the marine transgression shown by the overlying claystones of the Viking group. The Brent Group reservoirs, which lie at depths between 2300 and 2700 m, generally have excellent properties with porosities around 20–30% and permeabilities ranging up to several darcys. The Statfjord formation, which is of Ryazanian to Sinemurian age is separated from the Brent Group by the Dunlin Group, which is a non-reservoir sequence.
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The thermodynamic formalism allows that a system may have contact with several other systems at once, which may or may not also have mutual contact, the contacts having respectively different permeabilities. If these systems are all jointly isolated from the rest of the world those of them that are in contact then reach respective contact equilibria with one another. If several systems are free of adiabatic walls between each other, but are jointly isolated from the rest of the world, then they reach a state of multiple contact equilibrium, and they have a common temperature, a total internal energy, and a total entropy.Carathéodory, C. (1909).
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In sensory neurons, an external signal such as pressure, temperature, light, or sound is coupled with the opening and closing of ion channels, which in turn alter the ionic permeabilities of the membrane and its voltage. These voltage changes can again be excitatory (depolarizing) or inhibitory (hyperpolarizing) and, in some sensory neurons, their combined effects can depolarize the axon hillock enough to provoke action potentials. Some examples in humans include the olfactory receptor neuron and Meissner's corpuscle, which are critical for the sense of smell and touch, respectively. However, not all sensory neurons convert their external signals into action potentials; some do not even have an axon.
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In addition to a reduction in the rate of protein synthesis, it appears that some species of hypoxia-tolerant fish conserve energy by employing Hochachka's ion channel arrest hypothesis. This hypothesis makes two predictions: # Hypoxia- tolerant animals naturally have low membrane permeabilities # Membrane permeability decreases even more during hypoxic conditions (ion channel arrest) The first prediction holds true. When membrane permeability to Na+ and K+ ions was compared between reptiles and mammals, reptile membranes were discovered to be five times less leaky. The second prediction has been more difficult to prove experimentally, however, indirect measures have showed a decrease in Na+/K+-ATPase activity in eel and trout hepatocytes during hypoxic conditions.
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Gas mixtures can be effectively separated by synthetic membranes made from polymers such as polyamide or cellulose acetate, or from ceramic materials. Membrane cartridge While polymeric membranes are economical and technologically useful, they are bounded by their performance, known as the Robeson limit (permeability must be sacrificed for selectivity and vice versa). This limit affects polymeric membrane use for CO2 separation from flue gas streams, since mass transport becomes limiting and CO2 separation becomes very expensive due to low permeabilities. Membrane materials have expanded into the realm of silica, zeolites, metal-organic frameworks, and perovskites due to their strong thermal and chemical resistance as well as high tunability (ability to be modified and functionalized), leading to increased permeability and selectivity.
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Lower Bakken-3 Forks Transition Most Bakken wells are drilled and completed in the middle member. Many wells are now being drilled and completed in the basal Sanish/Pronghorn member and in the underlying Three Forks Formation, which the North Dakota Department of Mineral Resources treats as part of the Bakken for oil production statistical purposes. Porosities in the Bakken averages about 5%, and permeabilities are very low, averaging 0.04 millidarcys—much lower than typical oil reservoirs, in today's terms a light tight oil play.Diagenesis and Fracture Development in the Bakken formation, Williston Basin: Implications for Reservoir Quality in the Middle Member, by Janet K. Pitman, Leigh C. Price, and Julie A. LeFever, U.S. Geological Survey Professional Paper 1653, 2001.
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The pharmacology of a given P2X receptor is largely determined by its subunit makeup. Different subunits exhibit different sensitivities to purinergic agonists such as ATP, α,β-meATP and BzATP; and antagonists such as pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) and suramin. Of continuing interest is the fact that some P2X receptors (P2X2, P2X4, human P2X5, and P2X7) exhibit multiple open states in response to ATP, characterized by a time-dependent increase in the permeabilities of large organic ions such as N-methyl-D-glucamine (NMDG+) and nucleotide binding dyes such as propidium iodide (YO-PRO-1). Whether this change in permeability is due to a widening of the P2X receptor channel pore itself or the opening of a separate ion-permeable pore is the subject of continued investigation.
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Although it is not encountered in practice, the equations can also apply to the case of two media with a common permittivity but different refractive indices due to different permeabilities. From equations () and (), if ϵ is fixed instead of μ, then becomes inversely proportional to , with the result that the subscripts 1 and 2 in equations () to () are interchanged (due to the additional step of multiplying the numerator and denominator by ). Hence, in () and (), the expressions for and in terms of refractive indices will be interchanged, so that Brewster's angle () will give instead of and any beam reflected at that angle will be p-polarized instead of s-polarized.More general Brewster angles, for which the angles of incidence and refraction are not necessarily complementary, are discussed in C.L. Giles and W.J. Wild, "Brewster angles for magnetic media", International Journal of Infrared and Millimeter Waves, vol.
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As explained above, the potential at any point in a cell's membrane is determined by the ion concentration differences between the intracellular and extracellular areas, and by the permeability of the membrane to each type of ion. The ion concentrations do not normally change very quickly (with the exception of Ca2+, where the baseline intracellular concentration is so low that even a small influx may increase it by orders of magnitude), but the permeabilities of the ions can change in a fraction of a millisecond, as a result of activation of ligand-gated ion channels. The change in membrane potential can be either large or small, depending on how many ion channels are activated and what type they are, and can be either long or short, depending on the lengths of time that the channels remain open. Changes of this type are referred to as graded potentials, in contrast to action potentials, which have a fixed amplitude and time course.
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