Retrograde Condensation in Porous Media

1973 ◽  
Vol 13 (02) ◽  
pp. 93-104 ◽  
Author(s):  
P.M. Sigmund ◽  
P.M. Dranchuk ◽  
N.R. Morrow ◽  
R.A. Purvis
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Phase Behavior ◽  
Gas Condensate ◽  
Hydrocarbon Mixtures ◽  
Equilibrium Behavior ◽  
Miscible Displacements ◽  
Dry Sand ◽  
Gas Drive ◽  
Research Institute

SIGMUND, P.M., PETROLEUM RECOVERY RESEARCH INSTITUTE, CALGARY, ALTA., CANADA PETROLEUM RECOVERY RESEARCH INSTITUTE, CALGARY, ALTA., CANADA DRANCHUK, P.M., MEMBER SPE-AIME, U. OF ALBERTA EDMONTON, ALTA., CANADA MORROW, N.R., MEMBER SPE-AIME, PETROLEUM RECOVERY RESEARCH INSTITUTE, CALGARY, ALTA., CANADA PETROLEUM RECOVERY RESEARCH INSTITUTE, CALGARY, ALTA., CANADA PURVIS, R.A., MEMBERS SPE-AIME, PURVIS, R.A., MEMBERS SPE-AIME, ENERGY RESOURCES CONSERVATION BOARD, CALGARY, ALTA., CANADA Abstract The effect of porous media on the phase behavior of hydrocarbon binaries was investigated both experimentally and theoretically. When liquid and vapor coexist in a porous medium, the interlace between them will be curved. Calculations of the effect of curvature on phase behavior show that equilibrium composition and Pressures would not be disturbed significantly except at very high surface curvatures. Such curvatures are unlikely in hydrocarbon reservoirs even where clay-size particles are present because the finest pores will particles are present because the finest pores will be occupied by connate water. Measured dewpoint or bubblepoint pressures were found to be independent of the presence of porous media. Liquid saturations calculated from previous conventional phase behavior studies were compared with saturations calculated from the dimensions of a limited number of capillary structures which could be observed through the sight glass of a Jerguson cell. Saturations calculated from conventional phase-equilibrium data fell between saturations phase-equilibrium data fell between saturations calculated with The assumption that all capillary structures had equal curvature and those calculated with the assumption that they bad equal volumes. Introduction Reservoir engineering frequently involves the use of pressure-volume-temperature (PVT) relationships for hydrocarbon mixtures. Examples arise in reservoirs, and gas-drive miscible displacements, condensation and revaporization in gas condensate reservoirs, and gas-drive miscible displacements. The PVT relationships used in such engineering calculations are usually based on measurements on equilibrium behavior of hydrocarbon mixtures contained in PVT cells. For some time there has been question as to whether phase - behavior calculations made on data measured in such cells would correctly represent the behavior of hydrocarbon mixtures held within the interstices of porous reservoir rocks. The results of several recently reported experimental studies indicate that the presence of a porous medium has a significant influence presence of a porous medium has a significant influence on the equilibrium behavior of hydrocarbon mixtures. Trebin and Zadora contend that the initial condensation pressures (dew points) of gas condensate mixtures in pressures (dew points) of gas condensate mixtures in porous media can be 10 to 15 percent higher than those porous media can be 10 to 15 percent higher than those observed in conventional PVT cells. Tindy and Raynal reported that saturation pressures of crude oil in porous media were several percent higher than those porous media were several percent higher than those measured in conventional test cells. On the other hand, earlier results reported by Weinaug and Cordell indicated that vapor-liquid equilibrium relationships of the system methane-n-butane and methane-n-pentane were not affected by the presence of dry sand. Oxford and Huntington studied the revaporization of n-hexane by nitrogen and found that withdrawal rate and the presence of brine in the porous medium had little effect on the revaporization process. In a study of the effects of wettability change, process. In a study of the effects of wettability change, Smith and Yarborough concluded that the detailed form of the capillary structures of retrograde liquid held in a porous medium had no effect on the revaporization process. porous medium had no effect on the revaporization process. Clark studied the adsorption and desorption of light paraffinic hydrocarbons in clay and partially water-saturated paraffinic hydrocarbons in clay and partially water-saturated sand and sand-clay packs to determine their effect on equilibrium behavior. Compressibility factors for propane at 100 degrees F in the presence of dry sand-clay propane at 100 degrees F in the presence of dry sand-clay packs were lowered by 13 percent. However, in sand-clay packs were lowered by 13 percent. However, in sand-clay mixtures containing water, the compressibilities differed by less than 1 percent from those obtained in the absence of the porous media. Clark also studied effect of a dry sand-clay media on the PVT properties of mixtures of methane and propane. Only small changes were observed, and these were considered to be inconclusive - partly because the fluid was not recirculated through the porous media to ensure homogeneity. In summary, porous media to ensure homogeneity. In summary, evidence for the effect of porous media on equilibrium behavior is somewhat contradictory. SPEJ P. 93

Solvent Flooding Displacement Efficiency in Relation to Ternary Phase Behavior

1972 ◽  
Vol 12 (02) ◽  
pp. 89-95 ◽  
Author(s):  
Ahmad H.M. Totonji ◽  
S.M. Farouq Ali
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Phase Behavior ◽  
Ternary Phase ◽  
Ternary Systems ◽  
Ternary Mixtures ◽  
Displacement Mechanism ◽  
Irreducible Water Saturation ◽  
Experimental Runs

Abstract The chief objective of the study was to exercise control on the system phase behavior through the use of mixtures of two alcohols exhibiting opposite phase behavior characteristics in the alcohol-hydrocarbon-water system involved. Such systems were employed in displacements in porous media to ascertain their effectiveness. Introduction Displacement of oil and water in a porous medium by a mutually miscible alcohol or other solvent has been the subject of numerous investigations. This process, in spite of its limited scope as an oil recovery method, has certain mechanistic features that are of value in gaining an understanding of some of the newer recovery techniques (e.g., the Maraflood* process). The works of Gatlin and Slobod, proposing piston-like displacement of oil and water by a miscible alcohol; of Taber et al., describing the displacement mechanism in terms of the ternary phase behavior involved; and of Holm and Csaszar, defining displacement mechanism in terms of phase velocity ratio, are major contributions in this area. In a later work, Taber and Meyer suggested the addition of small amounts of oil and water (as the case may be) to the alcohol used for displacement, since this helped to obtain piston-like displacements with systems that are usually characterized by the efficient displacement of either oil or water. APPARATUS, EXPERIMENTAL PROCEDURE, AND SIMULATOR PROCEDURE, AND SIMULATOR The procedure employed for determining the equilibrium phase behavior of ternary systems involved the titration of a hydrocarbon-water (or brine) mixture by the particular solvent (pure alcohol, or alcohol mixture) for the determination of the binodal curve, and the analysis by refractive index measurement of ternary mixtures having known compositions for the determination of the tie lines. Since the procedure is valid for strictly ternary systems, its use in this case where essentially quaternary systems are involved would yield the total alcohol content rather than the correct proportion of each alcohol. The ternary diagrams presented should be viewed with this limitation in mind. presented should be viewed with this limitation in mind. The apparatus used for experimental runs in porous media consisted of a positive displacement Ruska pump and a core encased in a steel pipe. Suitable sampling apparatus and auxiliary equipment were employed. Most runs consisted of injecting a slug of the particular solvent into a core initially containing a residual oil (waterflood) or irreducible water saturation, at a constant rate, and then following the slug by water or brine. The effluent samples collected were analyzed for the hydrocarbon, water and alcohol in order to plot the production histories. Complete experimental details and fluid production histories. Complete experimental details and fluid properties are given in Ref. 6. Table 1 lists the properties properties are given in Ref. 6. Table 1 lists the properties of the porous media used. Computer simulations of some of the experimental runs, as well as exploratory simulations, were carried out using the method earlier reported. The method basically consists in the representation of a porous medium by a certain number of cells containing immobile oil (or oleic) and water (or aqueous) fractions into which alcohol is injected in a stepwise manner allowing for phase changes. SPEJ P. 89

The Influence of Phase Behavior on Surfactant Flooding

1979 ◽  
Vol 19 (06) ◽  
pp. 411-422 ◽  
Author(s):  
Ron G. Larson
Keyword(s):  
Porous Media ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Method Of Characteristics ◽  
Ternary Diagram ◽  
Base Case ◽  
Surfactant Flooding ◽  
Miscible Displacements ◽  
Tie Lines ◽  
Shed Light

Abstract This paper analyzes by mathematical modeling the role of phase behavior in surfactant flooding. In the absence of dispersion, miscible, immiscible, and semimiscible displacements are distinguished by the position of the injected composition relative to the position of the injected composition relative to the binodal envelope and extended tie lines. Even with dispersion, these concepts prove useful in analyzing slug miscibility breakdown in surfactant floods. Introduction Two design philosophies of tertiary oil recovery by surfactant flooding exist. In one, the chemical slug is designed to be miscible in some proportions with reservoir oil and brine, the goal being miscible displacement of resident oil. The second philosophy is to attain, rather than miscibility, philosophy is to attain, rather than miscibility, ultralow interfacial tension (IFT) between the slug fluid and resident oil. Correlations obtained by immiscible displacements of oil from natural and artificial porous media show that the saturation of residual oil (i.e. trapped, unrecoverable oil) decreases as IFT decreases. In reality, the distinction between philosophies is a matter of degree. Miscible displacements have regions of immiscibility. (e.g., the oil/brine bank). Furthermore, advocates of miscible displacements concede that breakdown into immiscible displacement occurs in the later stages of their processes; others argue that the breakdown occurs processes; others argue that the breakdown occurs early and that miscible displacements are, by and large, immiscible. On the other hand, since most slug formulations advocated by both schools are single phases capable of absorbing some amount of oil and phases capable of absorbing some amount of oil and brine without splitting into multiple phases, even chemical flood displacements designed to be immiscible are miscible for some time, however short. A related area of contention concerns the alleged advantages or disadvantages of formulating oil-rich, as opposed to brine-rich, slugs. Another area of contention concerns whether small, high-concentration chemical slugs are preferred to larger, lower-concentration slugs. The purpose of this paper is to shed light on these questions by paper is to shed light on these questions by incorporating equilibrium phase concepts as represented on a ternary diagram into the simulation of surfactant flood displacements. This study indicates that immiscible and miscible displacements are, in fact, closely related. Specifically, miscible recovery of oil is enhanced if the multiphase region of the ternary diagram contains a substantial subregion of ultralow tension. Furthermore, the success of miscible displacements is affected strongly not only by the position of the slug composition relative to the multiphase envelope on a ternary diagram but also by the position of slug composition relative to the tie lines, with better oil recovery attained when the injected composition point lies away from the region through which point lies away from the region through which extended tie lines pass. Thus, this study stresses the importance of the partition coefficient, a parameter shown to be important in an earlier study. For the purpose of this study, two simulation techniques for three-component, one- and two-phase flow in porous media were developed, each with its own restrictions. The first, a method-of-characteristics scheme (extended from a method developed earlier) allows phase volumes to change by solubilization of components phase volumes to change by solubilization of components but considers only continuous injection of micellar fluid, not the more realistic slug injection. The second method is a finite-difference approach that handles slug injection and solubilization and builds in dispersion, which cannot be considered when the method of characteristics is used. Because of the large number of parameters that arise in this study, base-case values (Table 1) of all parameters have been selected. For all results given in parameters have been selected. For all results given in this paper, the value of each parameter is the base-case value, unless otherwise specified. SPEJ P. 411

scholarly journals A Model for the Two-Phase Behavior of Fluids in Dilute Porous Media

1995 ◽  
Vol 407 ◽  
Author(s):  
James P. Donley ◽  
Rebecca M. Nyquist ◽  
Andrea J. Liu
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Simple Model ◽  
Phase Behavior ◽  
Silica Aerogel ◽  
Liquid Mixture ◽  
Liquid System ◽  
Coexistence Region ◽  
Two Phase ◽  
Binary Liquid

ABSTRACTExperiments show that the coexistence region of a vapor-liquid system or binary liquid mixture is dramatically narrowed when the fluid is confined in a dilute porous medium such as a silica aerogel. We propose a simple model of the gel as a periodic array of cylindrical strands, and study the phase behavior of an Ising system confined in this geometry. Our results suggest that the coexistence region should widen out at lower temperatures, and that the narrowness observed near the critical point may be a fluctuation-induced effect.

Miscibility Relationships in the Displacement of Oil By Light Hydrocarbons

1962 ◽  
Vol 2 (04) ◽  
pp. 340-346 ◽  
Author(s):  
W.M. Rutherford
Keyword(s):  
High Pressure ◽  
Critical Temperature ◽  
Phase Behavior ◽  
Experimental Methods ◽  
Miscible Displacement ◽  
Hydrocarbon Mixtures ◽  
West Texas ◽  
Displacement Experiments ◽  
The Subject ◽  
Gas Drive

Abstract A knowledge of the limits of miscibility between reservoir oil and possible injection fluids is required for selection of the optimum miscible-injection fluid. Limits of miscibility can be estimated from the results of equilibrium phase-behavior experiments. They can also be determined by means of displacement experiments conducted in a high-pressure sandpack. This paper describes the equipment and procedure which have been developed for determining miscibility conditions by stable displacement. A systematic series of displacements of a West Texas reservoir oil was carried out. The results indicate that, at constant pressure, miscibility is a function only of the pseudo critical temperature of the injection gas. This fact, together with improved experimental methods, makes the displacement technique a rapid, reliable means for determining miscibility conditions. In conjunction with the displacement experiments, phase diagrams were constructed for the oil with dry gas and propane and with dry gas and ethane. Phase behavior of the methane-ethane-propane system was determined at 110 degrees F. The experimental work demonstrates the feasibility of using ethane-rich gases to reduce cost and pressure requirements for miscible displacement. Introduction In recent years, interest in the miscible displacement of oil by light hydrocarbon mixtures has been high. Many pilot and a few field scale projects have been started. These projects have made use of various methods for achieving miscibility:the LPG-slug process,the enriched-gas-drive process andthe high-pressure gas-drive process. Some field projects have been successful; the results of others are debatable. In general, projects which have performed best have involved the injection of an appreciable fraction of a pore volume of miscible material. Economical application of miscible displacement depends strongly on the cost of the miscible-injection fluid. If an appreciable fraction of a pore volume of material is required for successful application of these methods, a precise knowledge of the minimum requirements for miscibility in terms of composition of injection fluid is essential. Therefore, reliable experimental methods for determining miscibility conditions are important, and a procedure for estimating these conditions from the composition of the reservoir fluid is highly desirable. The subject of this paper is the problem of determining conditions which result in miscible displacement of oil by light hydrocarbon mixtures. Miscibility conditions can be estimated by means of equilibrium experiments conducted in a PVT cell, or they can be determined by means of high-pressure displacement experiments. This paper describes the equipment and procedure which have been developed for the determination of miscibility by high-pressure displacement experiments. These methods have been applied to the displacement of a West Texas reservoir oil with mixtures of dry gas, ethane and propane. In conjunction with the displacement experiments, triangular phase diagrams have been constructed for mixtures of the oil with dry gas and propane and with dry gas and ethane. The effect of injection-gas composition on conditions for miscible displacement in high-pressure sandpacks and cores has been the subject of several published papers. The experimental methods used in these investigations were such that displacements were unstable, and the effects of fingering and/or gravity layover are clearly evident in the results. Miscibility conditions were probably correct in spite of the instability phenomena, but the experiments evidently were time-consuming, and limited data were reported. Systematic high-pressure flow studies which would support a correlation of miscibility conditions have not been reported; however, Wilson has proposed the use of pseudo critical temperature of the injection gas as a parameter and Benham, et al, have based a miscibility correlation on observed and calculated equilibrium data. SPEJ P. 340^

scholarly journals An evaluation on phase behaviors of gas condensate reservoir in cyclic gas injection

2020 ◽  
Vol 75 ◽  
pp. 4
Author(s):  
Angang Zhang ◽  
Zifei Fan ◽  
Lun Zhao ◽  
Anzhu Xu
Keyword(s):  
Phase Behavior ◽  
Gas Injection ◽  
Gas Condensate ◽  
Reservoir Pressure ◽  
Retrograde Condensation ◽  
Condensate Reservoir ◽  
Gas Drive ◽  
Phase Behaviors ◽  
Equilibrium Calculations ◽  
Better Than

Maintaining the reservoir pressure by gas injection is frequently adopted in the development of gas condensate reservoir. The aim of this work is to investigate the phase behavior of condensate oil and remaining condensate gas in the formation under gas injection. The DZT gas condensate reservoir in East China is taken as an example. The multiple contact calculation based on cell-to-cell method and phase equilibrium calculations based on PR Equation of State (EOS) were utilized to evaluate the displacement mechanism and phase behavior change. The research results show that different pure gas has different miscible mechanism in the displacement of condensate oil: vaporizing gas drive for N2 and CH4; condensing gas drive for CO2 and C2H6. Meanwhile, there is a vaporing gas drive rather than a condensing gas drive for injecting produced gas. When the condensate oil is mixed with 0.44 mole fraction of produced gas, the phase behavior of the petroleum mixture reverses, and the condensate oil is converted to condensate gas. About the reinjection of produced gas, the enrichment ability of hydrocarbons is better than that of no-hydrocarbons. After injecting produced gas, retrograde condensation is more difficult to occur, and the remaining condensate gas develops toward dry gas.

scholarly journals PHASE BEHAVIOR OF GAS-CONDENSATE FLUIDS DURING WELL TESTING

2015 ◽  
pp. 60-66
Author(s):  
M. L. Karnaukhov ◽  
M. . Maregatti ◽  
Sh. Z. Mirboboev ◽  
L. V. Kravchenko
Keyword(s):  
Porous Media ◽  
Phase Behavior ◽  
Gas Condensate ◽  
Well Testing ◽  
Gas Filtration ◽  
Characteristic Shape ◽  
Condensate Reservoir ◽  
Condensate Blockage

Hydrodynamic studies in gas-condensate wells allow determining the features of fluids flow in the gas condensate reservoir by build-up curves. A variation in the shape of the build-up curve may reflect a behavior of fluids in the reservoir, that is the nature of the fluids motion in porous media. The possibility of identification of characteristics of the combined liquid and gas filtration zone by build-up curves, as well as the radius of the zone of gas-condensate blockage is shown. Based on the examples of the log-log build-up graph in Venezuelan and Russian fields the exis-tence of the characteristic shape part on the build-up curves was demonstrated, evidencing the retrograde processes occurring in the reservoir.

Conservative solute transport with periodic velocity and sinusoidal source concentration in semi-infinite porous media: An analytical solution

2014 ◽  
Vol 6 (1) ◽  
pp. 1024-1031
Author(s):  
R R Yadav ◽  
Gulrana Gulrana ◽  
Dilip Kumar Jaiswal
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Laplace Transformation ◽  
Seepage Velocity ◽  
Transformation Technique ◽  
Numerical Examples ◽  
One Dimensional ◽  
Porous Domain ◽  
Conservative Solute Transport ◽  
Source Concentration

The present paper has been focused mainly towards understanding of the various parameters affecting the transport of conservative solutes in horizontally semi-infinite porous media. A model is presented for simulating one-dimensional transport of solute considering the porous medium to be homogeneous, isotropic and adsorbing nature under the influence of periodic seepage velocity. Initially the porous domain is not solute free. The solute is initially introduced from a sinusoidal point source. The transport equation is solved analytically by using Laplace Transformation Technique. Alternate as an illustration; solutions for the present problem are illustrated by numerical examples and graphs.

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