Summary This paper introduces a new method to screen crude oils for applicability of the air-injection/in-situ combustion process. Testing is performed at reservoir conditions, up to 41.4 MPa, with a specially modified accelerating-rate calorimeter (ARCTM). ARC results are shown for four medium- and high-gravity oils, combustion-tube data is presented, and air-injection field data are discussed and compared. We interpret that the continuity of the ARC trace ties in kinetics, combustion-tube, and field air-injection results. Thus, a method is available to delimit the envelope of applicability of air-injection/in-situ combustion to those oil reservoirs where the probability of technical and economic success is greatest. Introduction Air Injection for Crude-Oil Recovery. Air injection can offer unique economic and technical opportunities for improved oil recovery in many candidate reservoirs. Air injection is an efficient oil recovery process because only a small amount of the in-place oil is consumed while the rest is displaced, banked, and eventually produced. It has often been applied to heavy oils (for viscosity reduction owing to heat release) and sometimes to light oils. In the economically advantaged class of light-oil reservoirs, potential process benefits include the following.Excellent displacement efficiency and mobilization of extra, combustion oil.Reservoir pressurization.Flue gas stripping of the reservoir oil.Oil swelling.Injection-gas substitution. For air injection into high-pressure, hot reservoirs, the following additional benefits may accrue: spontaneous oil ignition and complete oxygen utilization, operation above the critical point of water with possible superextraction benefits, and near-miscibility of the generated flue gas and the oil.
Miscible gas flooding using an alternate gas/water injection process (AGWIP) is presently being applied for enhanced oil recovery (EOR) in several waterflooded reservoirs. 14 A mobile-water saturation in the vicinity of the miscible displacement front can occur in this process. To design field applications of miscible gas floods properly, it is necessary to understand the effects of water saturations above the connate saturation on the oildisplacement efficiency. Previous research on AGWIP has involved water-wet long-core flow tests using an injected solvent that is first-contact miscible with the inplace oil. 5-13 Miscible floods employing CO 2 , enriched gas, methane, and flue gases, however, are rarely firstcontact miscible with reservoir oils; the oil miscibility is normally achieved by a multiple-contact mechanism.This paper discusses the effects of mobile water on multiple-contact miscible displacements under waterand oil-wet conditions. Tests were conducted in 8-ft (244-cm) water-and oil-wet Berea cores in which C02 and water were injected both separately and simultaneously to displace a reservoir oil. The data presented focus on effects of water in the oil-moving zone (OMZ) where the CO 2 is generating miscibility with the oil and mobilizing residual oil to waterflooding. Special emphasis is placed on understanding the effect of mobilewater saturation on the oil-displacement efficiency and the component transfer between phases necessary to develop miscibility in the CO 2 /reservoir-oil system.This study demonstrates that reservoir wettability is a key factor in the performance of AGWIP. Gas/water injection can, under certain conditions, have adverse ef-0197· 7520/8310061-0687$00.25 JUNE 1983 fects on characteristics of the OMZ. These effects are in part caused by the water trapping portions of the oil and solvent. It was observed that mobile water did not change the mass transfer process by which miscibility develops in a multiple-contact miscible displacement.
Guidelines for sand control completion technique and gravel size selection are presented. These new criteria are based primarily on reservoir sand size distribution. Emphasis is on formations with very high fines content and a wide distribution of grain sizes. Upon failure and/or particle movement, these formations can exhibit very high skins and reduced production capacity with traditional control methods. Guidelines are also discussed for formations with little fines and a very uniform grain size distribution. Proposed criteria are based on field experience and experiments conducted with reservoir cores from different sand formations worldwide. Experiments were conducted by "packing" different gravels at the effluent end of core plugs and surging fluids through the plugs and gravel. Cases are presented where traditional methods would lead to an overly restrictive gravel pack and advantages are obtained with use of larger gravel. P. 201
Pressure, liquid-phase composition, and liquid-phase molar volume data are presented for the binary vapor-liquid systems C02-/rans-decalln at 0, 25, 50, and 75 °C and C02-n-butylbenzene at 0 and 20 °C. Also, pressure, liquidphase compositions, and molar volumes of the two coexisting liquid phases as a function of temperature are presented for the same binary systems along their Li-L2-V loci. The termination points of these loci are located and characterized.The authors have been engaged in studying the phase equilibria behavior of C02-hydrocarbon systems, with a view to providing data which would be useful for the design of economically attractive separation processes using C02 as a selective solvent. To date, the phase equilibria behavior of binary and ternary C02-hydrocarbon mixtures along liquid-vapor, solid-liquid-vapor, and liquid-liquid-vapor surfaces has been studied by Huie et al. (3), C02-n-decane-n-eicosane; Kulkarni et al. (5), C02-n-decane-2-methylnaphthalene; Zarah et al. ( 8), C02-n-butyibenzene-n-eicosane; and Yang et al. ( 7), C02n-butylbenzene-2-methylnaphthalene. These studies focused on systems high in the concentration of the heavier hydrocarbon
Pressure-temperature profiles along with liquid compositions and molar volumes are presented for two hydrocarbon solutes with methane as a common solvent. The data were taken employing cryoscopic techniques. In the case of the methane-cyclohexane system, the liquid compositional range covered extended from solute-rich solutions to very dilute solute solutions. Since reliable data on the methane-n-octane system in the solute-rich solution range are available, only the dilute solute range of this system was studied. The liquid compositional data when represented as the logarithm of composition vs. 7FUS/7 (where 7FUS = freezing temperature of each pure solvent) are smooth curves, with both binary systems possessing a maximum in composition at temperatures slightly below the critical temperature of methane. The curves become quite linear in the lower temperature range. The standard deviations of the liquid composition data are different for each system and for certain composition ranges as follows: methane-n-octane system, 5.0% for 191 > 7 > 155; methane-cyclohexane system, 0.76% for 279 > 7 > 190, 2.5% for 190 > 7> 154.
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