Mechanisms for High Displacement Efficiency of Low-Temperature CO2 Floods

SPE Journal ◽  
2011 ◽  
Vol 16 (04) ◽  
pp. 751-767 ◽  
Author(s):  
R.. Okuno ◽  
R.T.. T. Johns ◽  
K.. Sepehrnoori
Keyword(s):  
Low Temperature ◽  
Phase Behavior ◽  
Phase Region ◽  
Displacement Efficiency ◽  
Two Phase ◽  
Fixed Temperature ◽  
Three Phase ◽  
Minimum Number ◽  
Rich Liquid ◽  
Reservoir Simulator

Summary CO2 floods at temperatures typically below 120°F can involve complex phase behavior, where a third CO2-rich liquid (L2) phase coexists with the oleic (L1) and gaseous (V) phases. Results of slimtube measurements in the literature show that an oil displacement by CO2 can achieve high displacement efficiency of more than 90% when three hydrocarbon phases coexist during the displacement. However, the mechanism for the high-displacement efficiency is uncertain because the complex interaction of phase behavior with flow during the displacement is not fully understood. In this paper, we present the first detailed study of three-phase behavior predictions and displacement efficiency for low-temperature CO2 floods. Four-component EOS models are initially used to investigate systematically the effects of pressure, temperature, and oil properties on development of three-phase regions and displacement efficiency. Multicomponent oil displacements by CO2 are then considered. We use a compositional reservoir simulator capable of robust three-phase equilibrium calculations. Results show that high displacement efficiency of low-temperature CO2 floods is a consequence of both condensing and vaporizing behavior. The L2 phase serves as a buffer between the immiscible V and L1 phases within the three-phase region. Components in the L1 phase first transfer efficiently to the L2 phase near a lower critical endpoint (LCEP). These oil components then transfer to the V phase near an upper critical endpoint (UCEP) at the trailing edge of the three-phase region. The CEPs are defined where two of the three coexisting phases merge in the presence of the other immiscible phase. Unlike two-phase displacements, condensation and vaporization of intermediate components occur simultaneously within the three-phase region. The simultaneous condensing/vaporizing behavior involving the CEPs is also confirmed for simulations of several west Texas oil displacements. Quaternary fluid models can predict qualitatively the complex displacements because four is the minimum number of components to develop CEP behavior in composition space at a fixed temperature and pressure.

Analytical Solutions for Gas Displacements With Bifurcating Phase Behavior

SPE Journal ◽  
2014 ◽  
Vol 19 (05) ◽  
pp. 943-955 ◽  
Author(s):  
Saeid Khorsandi ◽  
Kaveh Ahmadi ◽  
Russell T. Johns
Keyword(s):  
Phase Behavior ◽  
Analytical Solutions ◽  
Phase Region ◽  
Co2 Injection ◽  
Two Phase ◽  
Complex Phase ◽  
Three Phase ◽  
Tie Lines ◽  
Tie Line ◽  
Composition Path

Summary Minimum miscibility pressure (MMP) is one of the most important parameters in the design of a successful gasflooding process. The most-reliable methods to calculate the MMP are based on slimtube experiments, 1D slimtube simulations, mixing-cell calculations, and the analytical methods known as the method of characteristics (MOC). The calculation of MMP by use of MOC is the fastest method because it relies solely on finding the key tie lines in the displacement path. The MOC method for MMP estimation in its current form assumes that the composition path is a series of shocks from one key tie line to the next. For some oils, however, these key tie lines do not control miscibility, and the MMP calculated by use of the key-tie line approach can be significantly in error. The error can be as high as 5,000 psia for heavier oils or CO2 displacements at low temperature in which three-phase hydrocarbon regions can exist (L1–L2–V). At higher pressures, the two- or three-phase region can split (or bifurcate) into two separate two-phase regions (L1–L2 and L1–V regions). Thus, for the MMP calculation from MOC to be correct, we must calculate the entire composition path for this complex phase behavior, instead of relying on the shock assumption from one key tie line to the next. In this paper, the MOC-composition route is developed completely for the bifurcating phase-behavior displacement for pure CO2 injection by use of a simplified pseudoternary system that is analogous to the complex phase behavior observed for several real displacements with CO2. We develop the MOC analytical solutions by honoring all constraints required for a unique solution—velocity, mass balance, entropy, and solution continuity. The results show that a combination of shocks and rarefaction waves exists along the nontie-line path, unlike previous MOC solutions reported to date. We show that by considering the entire composition path, not just the key tie lines, the calculated MMP agrees with the mixing-cell method. We also show that, in this complex ternary displacement, the displacement mechanism has features of a both condensing and vaporizing (C/V) drive, which was thought to be possible only for gasfloods with four or more components. For pure CO2 injection, the solution also becomes discontinuous for oils that lie on the tie line envelope curve. Finally, we show that shock paths within the two-phase region are generally curved in composition space and that there is no MMP for some oil compositions considered in the displacements by CO2. Recovery can be large even though the MMP is not reached.

Solution Properties and Phase Behavior of Ammonium Hexylene Octyl Succinate in Water and Water-Oil System

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
Md. Hamidul Kabir ◽  
Ravshan Makhkamov ◽  
Shaila Kabir
Keyword(s):  
Critical Micelle Concentration ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Carbon Number ◽  
Phase Region ◽  
Solution Properties ◽  
Middle Phase ◽  
Two Phase ◽  
Lamellar Liquid Crystal ◽  
Drug Ingredient

The solution properties and phase behavior of ammonium hexylene octyl succinate (HOS) was investigated in water and water-oil system. The critical micelle concentration (CMC) of HOS is lower than that of anionic surfactants having same carbon number in the lipophilic part. The phase diagrams of a water/ HOS system and water/ HOS/ C10EO8/ dodecane system were also constructed. Above critical micelle concentration, the surfactant forms a normal micellar solution (Wm) at a low surfactant concentration whereas a lamellar liquid crystalline phase (La) dominates over a wide region through the formation of a two-phase region (La+W) in the binary system. The lamellar phase is arranged in the form of a biocompatible vesicle which is very significant for the drug delivery system. The surfactant tends to be hydrophilic when it is mixed with C10EO8 and a middle-phase microemulsion (D) is appeared in the water-surfactant-dodecane system where both the water and oil soluble drug ingredient can be incorporated in the form of a dispersion. Hence, mixing can tune the hydrophile-lipophile properties of the surfactant. Key words: Ammonium hexylene octyl succinate, mixed surfactant, lamellar liquid crystal, middle-phase microemulsion. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Phase Equilibrium of Mg-Nd-Zn System near Mg-Nd Side at 400°C

2016 ◽  
Vol 873 ◽  
pp. 18-22
Author(s):  
Ming Li Huang ◽  
Xue Shen ◽  
Hong Xiao Li
Keyword(s):  
Solid Solution ◽  
Phase Equilibrium ◽  
Ternary Isothermal Section ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Maximum Solubility ◽  
Two Phase ◽  
Solubility Range ◽  
Three Phase ◽  
Equilibrium Alloys

The equilibrium alloys closed to Mg-Nd side in the Mg-rich corner of the Mg-Zn-Nd system at 400°C have been investigated by scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The binary solid solutions Mg12Nd and Mg3Nd with the solubility of Zn have been identified. The maximum solubility of Zn in Mg12Nd is 4.8at%, and Mg12Nd phase can be in equilibrium with Mg solid solution. However, only when the solubility range of Zn in 26at%~32.2at%, Mg3Nd can be in two-phase equilibrium with Mg solid solution. As the results, two two-phase regions as Mg+Mg12Nd and Mg+Mg3Nd and a three-phase region as Mg+Mg12Nd+Mg3Nd in Mg-Nd-Zn ternary isothermal section at 400°C have been identified.

Investigating Fuel Condensation Processes in Low Temperature Combustion Engines

2014 ◽  
Author(s):  
Lu Qiu ◽  
Rolf D. Reitz
Keyword(s):  
Low Temperature ◽  
Combustion Engine ◽  
Phase Region ◽  
Low Temperature Combustion ◽  
Combustion Engines ◽  
Two Phase ◽  
Temperature Combustion ◽  
Real Gas Effects ◽  
Unburned Hydrocarbons ◽  
Late Stages

Condensation of gaseous fuel is investigated in a low temperature combustion engine fueled with double direct-injected diesel and premixed gasoline at two load conditions. Possible condensation is examined by considering real gas effects with the Peng-Robinson equation of state and assuming thermodynamic equilibrium of the two fuels. The simulations show that three representative condensation events are observed. The first two condensations are found in the spray some time after the two direct injections, when the evaporative cooling reduces the local temperature until phase separation occurs. The third condensation event occurs during the late stages of the expansion stroke, during which the continuous expansion sends the local fluid into the two-phase region again. Condensation was not found to greatly affect global parameters, such as the average cylinder pressure and temperature mainly because, before the main combustion event, the condensed phase was converted back to the vapor phase due to compression and/or first stage heat release. However, condensed fuel is shown to affect the emission predictions, including engine-out particulate matter and unburned hydrocarbons.

Influence of Compressed Carbon Dioxide on the Oxidation of Cyclohexane with Hydrogen Peroxide in Acetic Acid

2006 ◽  
Vol 59 (3) ◽  
pp. 225 ◽  
Author(s):  
Liang Gao ◽  
Tao Jiang ◽  
Buxing Han ◽  
Baoning Zong ◽  
Xiaoxin Zhang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Binary System ◽  
Reaction System ◽  
Phase Region ◽  
Phase Behaviour ◽  
Phase System ◽  
Two Phase ◽  
Three Phase

The oxidation of cyclohexane with H2O2 in a compressed CO2/acetic acid binary system was studied at 60.0 and 80.0°C, at pressures up to 18 MPa, and with the zeolite TS-1 as catalyst. The phase behaviour of the reaction system was also observed. There are three fluid phases in the reaction system at lower pressure but two at higher pressures. In the three-phase region the yields of the products, cyclohexanol and cyclohexanone, increase considerably with increasing pressure and reaches a maximum near the phase-separating pressure. CO2 can thus enhance the reaction effectively. However, the effect of pressure on the yield is very limited after the transition to a two-phase system.

Phase Behavior of CO2 and Crude Oil in Low-Temperature Reservoirs

1981 ◽  
Vol 21 (04) ◽  
pp. 480-492 ◽  
Author(s):  
F.M. Orr ◽  
A.D. Yu ◽  
C.L. Lien
Keyword(s):  
Critical Temperature ◽  
Liquid Phase ◽  
Low Temperature ◽  
Crude Oil ◽  
Phase Behavior ◽  
Phase Diagrams ◽  
Ternary Mixtures ◽  
Co2 Flooding ◽  
Displacement Efficiency ◽  
Oil Mixtures

Abstract Phase behavior of CO2/Crude-oil mixtures which exhibit liquid/liquid (L/L) and liquid/ liquid/vapor (L/L/V) equilibria is examined. Results of single-contact phase behavior experiments for CO2/separator-oil mixtures are reported. Experimental results are interpreted using pseudoternary phase diagrams based on a review of phase behavior data for binary and ternary mixtures of CO2 with alkanes. Implications for the displacement process of L/L/V phase behavior are examined using a one-dimensional finite difference simulator. Results of the analysis suggest that L/L and L/L/V equilibria will occur for CO2/crude-oil mixtures at temperatures below about 120 degrees F (49 degrees C) and that development of miscibility occurs by extraction of hydrocarbons from the oil into a CO2-rich liquid phase in such systems. Introduction The efficiency of a displacement of oil by CO2 depends on a variety of factors, including phase behavior of CO2/crude-oil mixtures generated during the displacement, densities and viscosities of the phases present, relative permeabilities to individual phases, and a host of additional complications such as dispersion, viscous fingering, reservoir heterogeneities, and layering. It generally is acknowledged that phase behavior and attendant compositional effects on fluid properties strongly influence local displacement efficiency, though it also is clear that on a reservoir scale, poor vertical and areal sweep efficiency (caused by the low viscosity of the displacing CO2) may negate the favorable effects of phase behavior.Interpretation of the effects of phase behavior on displacement efficiency is made difficult by the complexity of the behavior of CO2/crude-oil mixtures. The standard interpretation of CO2 flooding phase behaviour, given first by Rathmell et al. is that CO2 flooding behaves much like a vaporizing gas drive, as described originally by Hutchinson and Braun. During a flood, vaporphase CO2 mixes with oil in place and extracts light and intermediate hydrocarbons. After multiple contacts, the CO2-rich phase vaporizes enough hydrocarbons to develop a composition that can displace oil efficiently, if not miscibly. The picture presented by Rathmell et al. appears to be consistent with phase behavior observed for CO2/ crudeoil mixtures as long as the reservoir temperature is high enough. Table 1 summarizes data reported for CO2/crude-oil mixtures. Of the 10 systems studied, all those at temperatures above 120 degrees F (50 degrees C) show only L/V equilibria while those below 120 degrees F exhibit L/L/V separations (Stalkup also reports two phase diagrams that are qualitatively similar to the other low-temperature diagrams but does not give temperatures). Thus, at temperatures not too far above the critical temperature of CO2 [88 degrees F (31 degrees C)], mixtures of CO2 and crude oil exhibit multiple liquid phases, and at some pressures L/L/V equilibria are observed. It has not been established whether Rathmell et al.'s interpretation of the process mechanism can be extended to cover the more complex phase behavior of low-temperature CO2/crude-oil mixtures. In a recent paper, Metcalfe and Yarborough argued critical temperature CO2 floods behave more like condensing gas drives, whereas Kamath et al. concluded that an increase in the solubility of liquid-phase CO2 in crude oil at temperatures near the critical temperature of CO2 should cause more efficient displacements of oil by CO2. SPEJ P. 480^

scholarly journals Pore-Scale Modelling of Three-Phase Capillary Pressure Curves Directly in Uniformly Wet Rock Images

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yingfang Zhou ◽  
Dimitrios Georgios Hatzignatiou ◽  
Johan Olav Helland ◽  
Yulong Zhao ◽  
Jianchao Cai
Keyword(s):  
Capillary Pressure ◽  
Water Saturation ◽  
Pore Space ◽  
Phase Region ◽  
Gas Oil ◽  
Two Phase ◽  
Sem Image ◽  
Three Phase ◽  
Scale Modelling ◽  
Capillary Pressure Curves

In this work, we developed a semianalytical model to compute three-phase capillary pressure curves and associated fluid configurations for gas invasion in uniformly wet rock images. The fluid configurations and favorable capillary entry pressures are determined based on free energy minimization by combining all physically allowed three-phase arc menisci. The model was first validated against analytical solutions developed in a star-shaped pore space and subsequently employed on an SEM image of Bentheim sandstone. The simulated fluid configurations show similar oil-layer behavior as previously imaged three-phase fluid configurations. The simulated saturation path indicates that the oil-water capillary pressure can be described as a function of the water saturation only. The gas-oil capillary pressure can be represented as a function of gas saturation in the majority part of the three-phase region, while the three-phase displacements slightly reduce the accuracy of such representation. At small oil saturations, the gas-oil capillary pressure depends strongly on two-phase saturations.

Phase-Behavior Properties of CO2 - Reservoir Oil Systems

1978 ◽  
Vol 18 (01) ◽  
pp. 20-26 ◽  
Author(s):  
Ralph Simon ◽  
A. Rosman ◽  
Erdinc Zana
Keyword(s):  
Interfacial Tension ◽  
Phase Behavior ◽  
Single Phase ◽  
Phase Region ◽  
Experimental Phase ◽  
Two Phase ◽  
Co2 Concentrations ◽  
Liquid Phases ◽  
Compositional Simulator ◽  
To Come

February 1978 Original manuscript received in Society of Petroleum Engineers office Jan. 14, 1977. Paper accepted for publication Aug. 15, 1977. Revised manuscript received Sept. 21, 1977. Paper (SPE 6387) was presented at the SPE-AIME Permian Basin Oil and Gas Recovery Conference, held in Midland, Tex., March 10-11, 1977. Abstract This paper presents experimental phase behavior data on two CO2-reservoir oil systems at reservoir pressures and temperatures. pressures and temperatures. The data includepressure-composition diagrams with bubble points, dew points, and critical points;vapor-liquid equilibrium compositions and related K values;vapor and liquid densities compared with values calculated by the Redlich-Kwong equation of state;vapor and liquid viscosities compared with predictions by the Lobrenz-Bray-Clark correlation; andinterfacial tensions for six vapor-liquid mixtures compared with values calculated by the Weinaug-Katz parachor equation. These and other published data contribute to development of the generalized correlations needed by reservoir and production engineers for evaluating, designing, and efficiently operating CO2-injection projects. projects Introduction This paper presents experimental phase behavior data for two CO2-reservoir oil systems. These data are used in predicting the performance of CO2 floods with a compositional simulator. The simulator calculates vapor and liquid compositions, densities, viscosities, and interfacial tensions to describe the phase behavior as the injected CO2 advances through phase behavior as the injected CO2 advances through the reservoir. The simulator predictions are used to evaluate proposed projects and to design and efficiently operate approved ones. The data in this paper consist of pressure-composition diagrams with bubble points, pressure-composition diagrams with bubble points, dew points, and critical points; and compositions, densities, viscosities, and interfacial tensions of vapors and liquids in equilibrium in the two-phase region. These data were obtained by the experimental procedure shown in Fig. 1. procedure shown in Fig. 1. We have compared our measured data with values calculated by existing methods: Redlich-Kwong equation for densities, Lohrenz-Bray-Clark correlation for viscosities, and the Weinaug-Katz parachor equation for interfacial tension. We found parachor equation for interfacial tension. We found that these published methods give acceptable agreement in some areas, but in general, they are not satisfactory for engineering purposes. Therefore, we conclude that improved calculation methods are needed for CO2 systems. For the special case of compositional simulator applications, we devised a technique for obtaining satisfactory calculated density, viscosity, and interfacial tension values. This technique is discussed in the section on "Measurements vs Calculations." We believe that our data, along with previously published information and information yet to come, published information and information yet to come, will advance the development of satisfactory correlations, thus reducing the need for extensive laboratory studies of individual systems. PRESSURE-COMPOSITION DIAGRAMS PRESSURE-COMPOSITION DIAGRAMS OIL A Ten mixtures of CO2 and Reservoir Oil A were prepared. These mixtures contained CO2 concentrations prepared. These mixtures contained CO2 concentrations of 0, 20, 40, 55, 60, 65. 70, 75, 80, and 90 mol percent. At 130 degrees F, pressure traverses were made with each mixture. These traverses started in the single-phase region at a pressure above the bubble (or dew) points and lowered the pressure in discrete steps, passing from the single-phase into the two-phase region. At each step, the vapor and liquid volumes were measured. The results are described in Fig. 2A. At 130 degrees F, the critical point of the CO2-Reservoir Oil A system (where intensive properties of the gas and liquid phases were equal) properties of the gas and liquid phases were equal) is 2,570 psia and 60-mol percent CO2. OIL B Eight mixtures of CO2 and Reservoir Oil B also were prepared and studied in the visual cell at 255 degrees F. CO2 concentrations for these mixtures were 0, 20, 40, 55, 65, 75, 80, and 85 mol percent. The pressure was varied from 800 to 6,100 psia, and the pressure was varied from 800 to 6,100 psia, and the relative vapor and liquid volumes measured. The results are given in Fig. 2B. The critical point of the CO2-Reservoir Oil B system at 255 degrees F is 4,890 psia and 74-mol percent CO2. psia and 74-mol percent CO2. SPEJ P. 20

Tie-Simplex-Based Phase-Behavior Modeling in an IMPEC Reservoir Simulator

SPE Journal ◽  
2013 ◽  
Vol 19 (02) ◽  
pp. 327-339 ◽  
Author(s):  
M.. Rezaveisi ◽  
K.. Sepehrnoori ◽  
R.T.. T. Johns
Keyword(s):  
Stability Analysis ◽  
Phase Behavior ◽  
Single Phase ◽  
Potential Method ◽  
Phase Region ◽  
Behavior Modeling ◽  
Computational Time ◽  
University Of Texas ◽  
Fully Implicit ◽  
Reservoir Simulator

Summary Recently, tie-simplex-based phase-behavior modeling in reservoir simulators has been applied and investigated as a potential method for improving the computational speed of equation-of-state (EOS) -based reservoir simulators. We implemented compositional-space adaptive tabulation (CSAT), the most promising tie-simplex-based method, in UTCOMP, the University of Texas' in-house IMPEC compositional reservoir simulator, to investigate its computational efficiency compared with the phase-behavior algorithm in UTCOMP. The results show that applying CSAT only to skip stability analysis does improve computational time, but only when a significant portion of the gridblocks are in the single-phase region and no other technique for avoiding stability analysis is used. However, in most cases, there is little or no computational advantage to use of CSAT when the simple option in UTCOMP is used where stability analysis is skipped for blocks surrounded by single-phase regions. We explore in detail the performance of CSAT, which depends significantly on the specific gas flood modeled, and the number of tie-lines generated during adaptive tabulation. The results shed light on applicability of CSAT in the IMPEC-type compositional reservoir simulators and show that the advantages of CSAT in this type of simulator are not as great as are reported in the literature for fully implicit or adaptive implicit formulations.

Multiple-Mixing-Cell Method for Three-Hydrocarbon-Phase Displacements

SPE Journal ◽  
2015 ◽  
Vol 20 (06) ◽  
pp. 1339-1349 ◽  
Author(s):  
Liwei Li ◽  
Saeid Khorsandi ◽  
Russell T. Johns ◽  
Kaveh Ahmadi
Keyword(s):  
Relative Permeability ◽  
Cell Model ◽  
Phase Identification ◽  
Displacement Efficiency ◽  
Compositional Simulation ◽  
Fractional Flow ◽  
Two Phase ◽  
Cell Method ◽  
Multiple Mixing ◽  
Three Phase

Summary Low-temperature oil displacements by carbon dioxide involve complex phase behavior, in which three hydrocarbon phases can coexist. Reliable design of miscible gasflooding requires knowledge of the minimum miscibility pressure (MMP), which is the pressure required for 100% recovery in the absence of dispersion or as defined by slimtube experiments as the “knee” in the recovery curve with pressure in which displacement efficiency is greater than 90%. There are currently no analytical methods to estimate the MMP for multicomponent mixtures exhibiting three hydrocarbon phases. Also, the use of compositional simulators to estimate MMP is not always reliable. These challenges include robustness issues of three-phase equilibrium calculations, inaccurate three-phase relative permeability models, and phase identification and labeling problems that can cause significant discontinuities and failures in the simulation results. How miscibility is developed, or not developed, for a three-phase displacement is not well-known. We developed a new three-phase multiple-mixing-cell method that gives a relatively easy and robust way to determine the pressure for miscibility or, more importantly, the pressure for high-displacement efficiency. The procedure that moves fluid from cell to cell is robust because it is independent of phase labeling (i.e., vapor or liquid), has a robust way to provide good initial guesses for three-phase flash calculations, and is also not dependent on three-phase relative permeability (fractional flow). These three aspects give the mixing-cell approach significant advantages over the use of compositional simulation to estimate MMP or to understand miscibility development. One can integrate the approach with previously developed two-phase multiple-mixing-cell models because it uses the tie-line lengths from the boundaries of tie triangles to recognize when the MMP or pressure for high-displacement efficiency is obtained. Application of the mixing-cell algorithm shows that, unlike most two-phase displacements, the dispersion-free MMP may not exist for three-phase displacements, but rather a pressure is reached in which the dispersion-free displacement efficiency is maximized. The authors believe that this is the first paper to examine a multiple-mixing-cell model in which two- and three-hydrocarbon phases occur and to calculate the MMP and/or pressure required for high displacement efficiency for such systems.

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