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^

Prediction of the Phase Behavior Generated by the Enriched-Gas-Drive Process

1965 ◽  
Vol 5 (02) ◽  
pp. 160-166 ◽  
Author(s):  
A.M. Rowe ◽  
I.H. Silberberg
Keyword(s):  
Computer Program ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Miscible Displacement ◽  
Phase Changes ◽  
Experimental Results ◽  
High Concentration ◽  
Gas Drive ◽  
Non Equilibrium ◽  
Vapor Liquid

Abstract A computer program was written to predict the phase behavior generated by the enriched-gas-drive process. This program is based, in part, on a new concept of convergence pressure, which is then used to select vapor-liquid equilibrium ratios (K-factors) for performing a series of flash calculations. The results of these calculations are the equilibrium vapor and liquid phase compositions which define the phase envelopes. The program was used to predict phase envelopes for 11 different hydrocarbon systems on which published experimental data were available. The predicted and experimental results compare favorably. Introduction The reservoir engineer is frequently faced with the problem of predicting what will happen if gas is injected into a reservoir. One aspect of this general problem is predicting the phase changes that will occur when a non-equilibrium gas displaces a reservoir fluid. In particular, a "dry" gas, upon displacing a volatile oil will pick up intermediate components from the oil. On the other hand, a "wet" gas, containing a high concentration of intermediates, will lose some of these components to a relatively low-gravity, non-equilibrium crude. It is this latter process, occurring in the enriched-gas displacement, which is treated in this paper. In the past, these phase changes have been determined experimentally and the results incorporated into various modifications of the Buckley-Leverett analysis. Such experimental work is time consuming, and the results are sensitive to numerous experimental errors. With the wide availability of high-speed digital computing equipment and numerous correlations pertaining to the vapor-liquid equilibria of hydrocarbon systems, it is now practical to calculate such phase behavior. This paper describes a computer program for performing these calculations. THE ENRICHED GAS DISPLACEMENT PROCESS Experimental results have shown that oil recovery can be significantly increased by enriching the displacing gas with intermediate hydrocarbon components. The essential features of the phase behavior generated by this enriched-gas-drive process are commonly illustrated with ternary diagrams such as Fig. 1. In this figure, Gas D, which contains a high concentration of intermediate hydrocarbons with respect to the undersaturated Crude A, is injected into the reservoir. When D contacts A, gas goes into solution until the oil becomes saturated (Point. B). Further contacting of Gas D and saturated Oil B results in a Mixture C which separates into Vapor Y(c) and Liquid X(c). Liquid X(c) is contacted by additional Gas D, resulting in Mixture E which separates into Vapor Y(e) and Liquid X(e). Repeated contacts of the liquid by the injected gas will eventually result in Liquid X(d) of maximum enrichment existing in equilibrium with Gas Y(d). The equilibrium tie-line X(d) Y(d), when extended, passes through the Point D representing the enriched injection gas. For systems of more than three components, the predicted equilibrium states are dependent upon not only reservoir temperature and pressure, but also the compositions of the crude oil and injected gas. If the gas is sufficiently enriched, a miscible displacement is generated. Line is tangent to the phase envelope at the critical point (Point Z) and represents the limiting slope of the tie-lines as the critical state is approached. Point I therefore represents the minimum enrichment of injection gas required to generate a miscible displacement. Point G represents the minimum enrichment required for initial miscibility of the injection gas with Crude A.Attra has presented a method to be used for prediction of oil recovery by the enriched gas displacement process. To develop the phase behavior data needed, he designed the experimental procedure described in the following quotation from his paper SPEJ P. 160ˆ

Solvent and Driving Gas Compositions for Miscible Slug Displacement

1970 ◽  
Vol 10 (03) ◽  
pp. 298-310 ◽  
Author(s):  
Lyman Yarborough ◽  
L.R. Smith
Keyword(s):  
Crude Oil ◽  
Phase Behavior ◽  
Nitrogen Concentration ◽  
Equilibrium Phase ◽  
Miscible Displacement ◽  
Limiting Factor ◽  
Liquefied Petroleum Gas ◽  
Contact Zones ◽  
Wide Range ◽  
Gas Drive

Abstract Experimental data were used for determining miscibility in liquefied petroleum gas (LPG) slug flooding and enriched gas drive of crude oils. The miscibility data for LPG slug flooding includes cases where the driving gas contains large amounts of nitrogen and when low pressure miscible displacement is desired. The results of flow tests for enriched gases miscibly displacing crude oil are given. These data cover a wide range of reservoir oil properties and miscibility pressures. Methods for predicting compositional requirements for both miscible slug displacement processes are recommended and should be useful for preliminary engineering evaluation of miscible slug displacement for a reservoir. Introduction The two most frequently applied hydrocarbon solvent processes for miscible displacement of crude oil are liquefied petroleum gas (LPG) slug flooding and enriched gas drive. A slug of the LPG or enriched gas is injected and followed by dry gas or gas-water displacement. In both cases the injected material forms a miscible slug in the reservoir. Generally, there are two fluid contact zones in which the establishment of miscibility must be considered as related to the fluid compositions and the reservoir temperature and pressure. The first zone is the solvent-reservoir oil pressure. The first zone is the solvent-reservoir oil contact zone; the second zone is where the lean scavenging gas and solvent come together. For successful miscible displacement, there must be single-hydrocarbon-phase condition throughout both contact zones. Aside from possible repressuring procedures which may be undertaken prior to solvent procedures which may be undertaken prior to solvent injection, the primary engineering control for achieving miscibility is the proper specification of the solvent and driving gas compositions. This paper discusses the compositional requirements for paper discusses the compositional requirements for miscibility to be achieved in both contact zones and considers cases where the reservoir pressure is very low or the driving gas contains a large amount of nitrogen. LPG SLUG FLOODING FOR MISCIBLE DISPLACEMENT OF CRUDE OIL In LPG slug flooding there is no problem in achieving miscibility with the crude oil under conditions where the solvent remains liquid. Miscibility between the LPG slug and the driving gas may be the limiting factor. At pressures below 1,100 to 1,200 psia, miscibility often cannot be achieved between the LPG and driving gas, and even higher pressures may be required if the available driving gas contains an appreciable concentration of nitrogen. Another area of increasing interest is LPG slug flooding in reservoirs where the pressure is 1,000 psia or below. At these pressures the methane-LPG transition cannot be pressures the methane-LPG transition cannot be single phase at temperatures below 160 degrees F. The only practicable approach to achieving miscible displacement under these conditions is to inject an ethane-rich buffer slug between the LPG and the driving gas. To determine the allowable nitrogen concentration for gases driving LPG, the phase behavior of nitrogen-methane-propane mixtures was experimentally studied at 105 degrees and 120 degrees F. Similarly, equilibrium-phase behavior data were obtained for the methane-ethane-propane system at 105 degrees F. The latter results allow estimates to be made of the buffer-slug composition necessary for miscible displacement at low pressures. Also, the effects of small amounts of butane and pentane on the phase behavior of the nitrogen-methane-propane and the nitrogen-methane-ethane-propane system were studied. SPEJ p. 278

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

Using Phase surfaces to Describe Condensing-Gas-Drive Experiments

1965 ◽  
Vol 5 (03) ◽  
pp. 184-185
Author(s):  
Fred I. Stalkup
Keyword(s):  
Phase Behavior ◽  
Miscible Displacement ◽  
Ternary Diagram ◽  
Dew Point ◽  
Plait Point ◽  
Bubble Point ◽  
Reservoir Fluid ◽  
Point Curve ◽  
The Rich ◽  
Gas Drive

Stalkup, Fred I., Junior Member AIME, The Atlantic Refining Co., Dallas, Tex. Abstract Vapor-liquid phase equilibrium experiments have been conducted in a static equilibrium cell on mixtures of a light, 450 API stock-tank gravity reservoir fluid and a rich hydrocarbon gas containing approximately 55 mole per cent of intermediate hydrocarbons. Both a pressure-vs-composition study of the gas and a simulated reservoir fluid, and a multiple-batch contact simulation of the condensing-gas-drive oil recovery process were performed. In the latter experiments equilibrium gas and liquid compositions were analyzed. Also, conventional, "condensing-gas-drive", long-tube displacement experiments of the reservoir fluid and gases of various richness were performed. The results of these experiments could not be satisfactorily interpreted by the conventional pseudo-ternary-diagram representation of multicomponent phase behavior. The results seem to be explained better by considering a bubble-point surface and a dew-point surface joined in a plait-point locus. Portions of the plait-point locus cannot be "seen" directly by the rich hydrocarbon gas because of curvature of the dew-point surface. In such a system, continuous injection of the rich gas over stationary reservoir fluid might form a zone of contiguously miscible compositions from pure rich gas to pure reservoir fluid by:saturating the reservoir fluid with injected gas to the bubble-point surface;creating by mass transfer with fresh injected gas a path of contiguously miscible compositions along the bubble-point surface to the plait-point locus; andcreating by mass transfer with additional injected gas a path of gas compositions along the dew-point surface up to the point where direct miscibility results between dew-point fluid and the injected rich gas. Introduction The use of the pseudo-ternary-phase diagram to illustrate miscible displacement phase behavior has been discussed by several authors. Such a representation of phase behavior is not rigorous, but the ternary diagram nevertheless gives a qualitative picture of what actually occurs in a miscible displacement process. Fig. 1 is a typical illustration of miscible displacement phase behavior by a ternary diagram. The multicomponent hydrocarbon system is divided into three pseudo-components: a light fraction containing methane and nitrogen, an intermediate fraction containing ethane through hexanes plus carbon dioxide, and a heavy fraction containing heptane and heavier components. A two-phase region is bounded by a dew-point curve and a bubble-point curve, which are joined at the critical point. The concept deduced from such a representation for miscible displacement by a condensing-gas-drive process is as follows: a rich gas G, which lies to the right of the limiting tie line through the critical point C, is injected into the reservoir and contacts reservoir fluid L, saturating the reservoir fluid to give bubble-point fluid L1 and equilibrium dew-point gas G1. Continued injection of rich gas changes the composition of the saturated liquid L1 through a series of liquid compositions lying along the bubble-point curve, until the critical composition C is reached, at which point direct miscibility with the rich gas is achieved. Some equilibrium gas with compositions lying along the dew-point curve from G1 to C is also formed in this process. SPEJ P. 184ˆ

Phase equilibria modeling of biorefinery-related systems: a systematic review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Marcos L. Corazza ◽  
Julia Trancoso
Keyword(s):  
Phase Equilibria ◽  
Phase Behavior ◽  
Fossil Fuel ◽  
Process Conditions ◽  
Design And Optimization ◽  
Waste Reuse ◽  
Wide Range ◽  
Prisma Statement ◽  
Fuel Substitution ◽  
The Subject

Abstract The search for sustainable ideas has gained prominence in recent decades at all levels of society since it has become imperative an economic, social, and environmental development in an integrated manner. In this context, biorefineries are currently present as the technology that best covers all these parameters, as they add the benefits of waste reuse, energy cogeneration, and fossil fuel substitution. Thus, the study of the various applicable biological matrices and exploring the technical capabilities of these processes become highly attractive. Thermodynamic modeling acts in this scenario as a fundamental tool for phase behavior predictions in process modeling, design, and optimization. Thus, this work aimed to systematize, using the PRISMA statement for systematic reviews, the information published between 2010 and 2020 on phase equilibria modeling in systems related to biorefineries to organize what is already known about the subject. As a result, 236 papers were categorized in terms of the year, country, type of phase equilibria, and thermodynamic model used. Also, the phase behavior predictions of different thermodynamic models under the same process conditions were qualitatively compared, establishing PC-SAFT as the model that best represents the great diversity of interest systems for biorefineries in a wide range of conditions.

V. Experimental researches in magnetism and electricity

1867 ◽  
Vol 157 ◽  
pp. 89-107 ◽  
Keyword(s):  
High Pressure ◽  
Quantitative Relation ◽  
Feed Water ◽  
Dynamic Force ◽  
Electric Induction ◽  
Similar Character ◽  
The Subject ◽  
The One ◽  
Experimental Researches ◽  
The Universe

1. The principle of the conservation of force, as I apprehend it, is the definite quantitative relation existing between all the phenomena of the universe whatsoever, both in direction and amount, whether such phenomena be considered in the relation of cause and effect, or as antecedent and consequent events. 2. In the particular application of this principle to the advancement of physical science, and also to the invention of new engines and machinery to meet the progressive requirements of society, problems not unfrequently present themselves which involve the consideration of static and dynamic force, from several different aspects; and the solution of these problems often brings out results which are as surprising as they are paradoxical. Of such cases, in which the idea of paradox alluded to is involved, may be mentioned the one contained in the 36th Proposition of Newton’s 'Principia' (Book 2, Cor. 2), and in D. Bernoulli’s 'Hydrodynamica,' p. 279; in which the repulsive force of a jet of Water issuing from a hole in the bottom or side of a vessel with a velocity which a body would acquire in falling freely from the surface, is equal to the weight of a column of water of which the base is equal to the section of the contracted vein and about twice the height of the column which produces the flowing pressure; the static force of reaction being thus double that which, without experiment, had been predicted. An instance in which the quantity of dynamic force is increased paradoxically may be seen in that curious and useful piece of apparatus the injector, by means of which a boiler containing steam of high pressure is able to feed itself with water through a hole in its shell, though this hole is open to the atmosphere; or the steam from a low-pressure boiler is enabled to drive the feed-water through a hole (also open to the atmosphere) into a high-pressure boiler. Although, when rightly interpreted, these examples of paradox, as well as many others of a similar character, are in strict accordance with the principle of conservation, yet they are at the same time contrary to the inferences which are generally drawn from analogical reasonings, and to some of those maxims of science which are framed for the instruction of the unlearned. As the examples cited are only adduced for the purpose of illustrating some analogous phenomena observed in connexion with certain combinations of static and dynamic force in molecular mechanics which form the subject of the present research, it is not my intention to enter into the rationale of either of them, but to direct attention to some new and paradoxical phenomena arising out of Faraday’s important discovery of magneto-electric induction, the close consideration of which has resulted in the discovery of a means of producing dynamic electricity in quantities unattainable by any apparatus hitherto constructed.

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