Analysis of the Physical Mechanisms in Surfactant Flooding

1978 ◽  
Vol 18 (01) ◽  
pp. 42-58 ◽  
Author(s):  
R.G. Larson
Keyword(s):  
Mass Transfer ◽  
Oil Recovery ◽  
Surfactant Flooding ◽  
Constant Composition ◽  
Phase Boundaries ◽  
One Dimensional ◽  
Mobile Phases ◽  
Immobile Phase ◽  
Oil Water ◽  
Core Flood

Abstract A model was developed to represent the physical displacement mechanism of tertiary oil recovery in an aqueous-phase surfactant flood. The chemical aspects were not modeled. In particular, the residual oil saturation in the presence of surfactant must be specified to use the model. This model was used to investigate the relationship between the system parameters (mobility ratio, partition coefficient, parameters (mobility ratio, partition coefficient, adsorption) and the performance variables (oil cut, chemical breakthrough, recovery efficiency at breakthrough). The model is an extension of Buckley-Leverett analysis and applies to the flow of two fluids in a system in which composition and saturation are variables. This model assumes a homogeneous one-dimensional system, the absence of dispersion, equilibrium mass transfer, and constant composition injection (infinite slug). Analysis applies to systems of two mobile phases (oil and water) and one immobile phase (reservoir rock) where three components (oil, water, and chemical) transfer between mobile phases. and chemical transfers to the rock. The model predicts that oil recovery and surfactant breakthrough may be retarded in low-tension surfactant floods where the surfactant partitions preferentially into the oil phase. This partitions preferentially into the oil phase. This prediction is confirmed by experimental core-flood prediction is confirmed by experimental core-flood results. Introduction In designing and optimizing a surfactant-flooding process, one is confronted with many mechanisms process, one is confronted with many mechanisms and corresponding physicochemical properties of the rock and fluid interactions that affect performance of a surfactant flood. Important properties are relative permeabilities, viscosities, interfacial tensions, dispersion coefficients, and adsorption isotherms. Laboratory investigation of these mechanisms is hampered by the high degree of coupling among mechanisms, which makes it difficult to analyze process sensitivity to each property. property. Therefore, a simple mathematical model was developed to interpret results of core-flooding experiments and to apply in cases in which surfactant is injected continuously (infinite slug). A sensitivity study of the effect of 14 model parameters on oil recovery revealed that recovery parameters on oil recovery revealed that recovery is affected strongly by pore-to-pore displacement efficiency (governed by interfacial tension) and fluid mobilities, and by interphase mass transfer of chemical (surfactant), oil, and water. The effect of this transfer phenomenon on surfactant-flood oil recovery previously has received little attention. ASSUMPTIONS OF THE MODEL SYSTEM The system is one-dimensional with uniform properties. properties. Two mobile fluid phases, an aqueous displacing phase, and an oleic displaced phase are considered, as well as one immobile phase (rock). Three mobile components (oil, water, and chemical) are considered. Each is assumed to behave as if it was a pure component. Mass transfer of chemical, water, and oil between the mobile phases and transfer of chemical to the immobile phase is allowed. The mass transfer rates are assumed sufficiently fast compared with fluid flow that chemical equilibrium exists across phase boundaries everywhere in the reservoir. phase boundaries everywhere in the reservoir. Initially, the reservoir contains pure oil at its waterflood residual oleic-phase saturation (Sorw), and the rest of the pore space contains pure water. The injected fluid is a single aqueous phase at constant composition (infinite slug injection). This injected composition lies on the two-phase envelope of a ternary diagram (that is, no phase extraction). The system is self-sharpening in that only the injected and the initial compositions exist in the composition profile. (Sufficient valid conditions for this assumption are derived in Appendix B.) There are no chemical reactions. In each phase, each component occupies the volume it would have in its pure state (VE = O, the excess volume of mixing is zero). SPEJ p. 42

scholarly journals Evaluating the potential of surface-modified silica nanoparticles using internal olefin sulfonate for enhanced oil recovery

2019 ◽  
Vol 17 (3) ◽  
pp. 722-733 ◽  
Author(s):  
Afaque Ahmed ◽  
Ismail Mohd Saaid ◽  
Abdelazim Abbas Ahmed ◽  
Rashidah M. Pilus ◽  
Mirza Khurram Baig
Keyword(s):  
Silica Nanoparticles ◽  
Rheological Properties ◽  
Oil Recovery ◽  
Displacement Efficiency ◽  
Shear Rates ◽  
Oil Water ◽  
Core Flood ◽  
The Stability ◽  
Modified Silica Nanoparticles ◽  
Surface Modified

AbstractRecently, nanoparticles have proven to enhance oil recovery on the core-flood scale in challenging high-pressure high-temperature reservoirs. Nanomaterials generally appear to improve oil production through wettability alteration and reduction in interfacial tension between oil and water phases. Besides, they are environmentally friendly and cost-effective enhanced oil recovery techniques. Studying the rheological properties of nanoparticles is critical for field applications. The instability of nanoparticle dispersion due to aggregation is considered as an unfavorable phenomenon in nanofluid flooding while conducting an EOR process. In this study, wettability behavior and rheological properties of surface-treated silica nanoparticles using internal olefins sulfonates (IOS20–24 and IOS19–23), anionic surfactants were investigated. Surface modification effect on the stability of the colloidal solution in porous media and oil recovery was inspected. The rheology of pure and surface-treated silica nanoparticles was investigated using a HPHT rheometer. Morphology and particle size distributions of pure and coated silica nanoparticles were studied using a field emission scanning electron microscope. A series of core-flood runs was conducted to evaluate the oil recovery factor. The coated silica nanoparticles were found to alter rheological properties and exhibited a shear-thinning behavior as the stability of the coated silica nanoparticles could be improved considerably. At low shear rates, the viscosity slightly increases, and the opposite happens at higher shear rates. Furthermore, the surface-modified silica nanoparticles were found to alter the wettability of the aqueous phase into strongly water-wet by changing the contact angle from 80° to 3° measured against glass slides representing sandstone rocks. Oil–water IFT results showed that the surface treatment by surfactant lowered the oil–water IFT by 30%. Also, the viscosity of brine increased from 0.001 to 0.008 Pa s by introducing SiO2 nanoparticles to the aqueous phase for better displacement efficiency during chemical-assisted EOR. The core-flood experiments revealed that the ultimate oil recovery is increased by approximately 13% with a surfactant-coated silica nanofluid flood after the conventional waterflooding that proves the potential of smart nanofluids for enhancing oil recovery. The experimental results imply that the use of surfactant-coated nanoparticles in tertiary oil recovery could facilitate the displacement efficiency, alter the wettability toward more water-wet and avoid viscous fingering for stable flood front and additional oil recovery.

scholarly journals INCREASING OIL RECOVERY APPLYING ELECTRIC STIMULATION ON THE FORMATION

2021 ◽  
Author(s):  
Bahshillo Akramov ◽  
◽  
Sherali Umedov ◽  
Odiljon Khaitov ◽  
Jaloliddin Nuriddinov ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Electric Field ◽  
Electric Fields ◽  
Oil Recovery ◽  
Experimental Studies ◽  
Surface Tension Coefficient ◽  
Recovery Factor ◽  
Water Interface ◽  
Oil Water

The work is devoted to increasing the degree of depletion of reserves of longterm exploited hydrocarbon deposits on the basis of the obtained results of theoretical and experimental studies of the application of electrodynamic technologies for stimulating the formation and bottomhole formation zone. The electrolysis of formation fluids, water, oil-bearing rocks, is accompanied by a mass transfer, primary and secondary chemical reactions, the formation of all kinds of salts, alkalis and acids, new organic substances and all kinds of surfactants. Not only the liquid is subjected to electrolysis, but also the oil and gas bearing rocks themselves (solid electrolyte). The magnetic and electrical forces arising during the electric treatment of reservoirs make it possible to effectively drain heterogeneous reservoirs and extract residual oil from non-working layers. The work also carried out experiments to study the effect of the electric field on the surface tension coefficient at the oil-water interface. The circumstance of an abrupt change in the surface tension coefficient at the oil-water interface makes it possible in principle to create conditions in the reservoir that make it possible to slow down the cusping processes by applying an electric field of various magnitudes or, in other words, by regulating the amount of mass transfer. In numerical terms, the oil recovery factor without electrophysical treatment was 52.94%. Under electrophysical impact, the oil recovery factor was 94.12%, i.e. equaled to almost complete extraction of oil from the sample. In the field, this figure, of course, will decrease by 2-3 times, but it remains quite high in comparison with other methods of increasing oil recovery. Thus, the studies performed on samples in laboratory conditions indicate the possibility of using constant electric fields to increase oil recovery from depleted watered formations. Electrochemical treatment of the formation can significantly increase the displacement of oil from the formation. The increase in oil displacement reaches 15-20% and more. With the help of water alone, 58% of the oil (of its total volume in the sand) was displaced from the sand, and under electric field with a voltage of 10 V and 20 V, the total amount of displaced oil, respectively, increased to 67 and 83%. Thus, the laboratory studies performed on the samples also indicate the possibility of using constant electric fields to increase oil recovery from depleted watered formations. The carried out theoretical and experimental studies show the possibility of using the technology of electrochemical and electrothermochemical leaching of oilsaturated rocks to intensify oil production. The effectiveness of the recommended technology is especially noticeable in fields that have entered the final stage of development with a high water cut.

A Numerical Study of Diphasic Multicomponent Flow

1972 ◽  
Vol 12 (02) ◽  
pp. 171-184 ◽  
Author(s):  
N. Van-Quy ◽  
P. Simandoux ◽  
J. Corteville
Keyword(s):  
Mass Transfer ◽  
Oil Recovery ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Simple Fluids ◽  
Oil Saturation ◽  
One Dimensional ◽  
Convection Diffusion ◽  
Gas Drive

Abstract This paper describes a general multicomponent two-phase flow model, taking into account convection, diffusion and thermodynamic exchange between phases. The main assumptions are: isothermal one-dimensional flow; two-phase flow (gas and liquid); each phase may be represented by a mixture of three components or groups of components. Actually, a great many recovery problems cannot be pictured by usual models because the oil and, in many cases, the injected fluid are not simple fluids and may bring about exchanges of components that considerably modify their characteristics. This is why efforts are now being made to develop "compositional" or "multicomponent" models capable of solving such situations. Generalization of the model to more complex systems can be considered. Cases treated may be any type of single- and two-phase flow, in particular any miscible process (e. g., high-pressure gas drive, condensing gas drive, slug displacement) and any diphasic processes with high mass exchange (e.g., displacement by carbon dioxide or flue gas). This model is working and has been successfully checked by experiments. Introduction Many investigations, broth experimental and theoretical, have been made on the recovery of oil from reservoirs. With regard to mathematical models, most of those conceived up to now have dealt with oil recovery by the injection of a fluid that is miscible or immiscible with the oil. For miscible drives, single-phase flow with a binary mixture and miscibility in all proportions is involved. In such an ideal situation oil recovery is theoretically total. For immiscible displacements flow is diphasic. Capillary pressure and relative permeability play a preponderant role. Since irreducible oil saturation preponderant role. Since irreducible oil saturation is inevitable, oil recovery can never be total. Actually, a great many recovery problems cannot be pictured by such models because the oil and, in many cases, the injected fluid are not simple fluids and may bring about exchanges of components that considerably modify their characteristics. This is why efforts are now being made to develop "compositional" or "multicomponent" models capable of solving such situations. Such a model is described here. It is designed to handle the most general case of the displacement of one fluid by another. This model offers the following possibilities.The fluids may be made up of more than two components.Flow may be entirely monophasic, entirely diphasic, or partially monophasic and diphasic.Miscibility may be partial or total.The material exchange between phases may take place under specific thermodynamic conditions. A model that is much closer to reality should provide more thorough knowledge of mass transfer provide more thorough knowledge of mass transfer mechanisms in a complex mixture as well as better oil recovery forecasting with the injection of a second fluid. DESCRIPTION OF THE MODEL In a porous formation, we will consider the displacement of a liquid hydrocarbon complex in place by another fluid that is injected into the place by another fluid that is injected into the formation. The injected fluid may be a gas or a liquid, containing or not containing hydrocarbons. We assume that the mass transfer in the transition zone between the displacing fluid and the displaced fluid occurs according to three mechanism: convection, diffusion and thermodynamic exchange between phases. We propose to study the flow thus described. The main assumptions are:flow is isothermal and one-dimensional;the porous medium is homogeneous and isotropic;there is no effect of gravity;there is a two-phase flow, i.e., oil and gaseach phase may be represented by a mixture of three components or three groups of components (e.g., C1, C2-6, C7+); SPEJ P. 171

Numerical Three-Phase Model of the Two-Dimensional Steamflood Process

1970 ◽  
Vol 10 (04) ◽  
pp. 405-417 ◽  
Author(s):  
N.D. Shutler
Keyword(s):  
Fluid Flow ◽  
Cross Section ◽  
Oil Recovery ◽  
Vertical Cross Section ◽  
Recovery Efficiency ◽  
Two Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Oil Water ◽  
Three Phases

Abstract This paper describes a numerical mathematical model that is a significant extension of a previously published one-dimensional model of the steamflood published one-dimensional model of the steamflood process. process. The model describes the simultaneous flow of the three phases - oil, water and gas - in two dimensions. Interphase mass transfer between water and gas phases is allowed, but the oil is assumed nonvolatile and the hydrocarbon gas insoluble in the liquid phases. The model allows two-dimensional heat convection within the reservoir and two-dimensional heat conduction in a vertical cross-section spanning the oil sand and adjacent strata. Example calculations are presented which, on comparison with experimental results, tend to validate the model. Steam overriding due to gravity effects is shown to significantly reduce oil recovery efficiency in a thick system while jailing to do so in a thinner system. A study of the effect of capillary pressure indicates that failure to scale capillary forces in laboratory models of thick sands may lead to optimistic recovery predictions, while properly scaled capillary forces may be sufficiently low as to play no important role in oil recovery. Calculations made with and without vertical permeability show that failure to account for vertical fluid flow can lead to predictions of pessimistic oil recovery efficiency. pessimistic oil recovery efficiency Introduction Mathematical tools of varying complexity have been used in studying the steamflood process. A "simplified" class of mathematical models has served primarily as aids in engineering design. A more comprehensive class of models has improved understanding of the nature of the process. The model described in this report is of the latter class, but it is more comprehensive than any previously published model. published model. All previously available calculations of the steamflood process are confined to one space dimension in their treatments of fluid flow. Thus all previous models necessary ignore all effects of gravity reservoir heterogeneity, and nonuniform initial fluid-phase distributions on fluid flow in a second dimension. This model, an extension of a previously published model accounts for heat and previously published model accounts for heat and fluid transfer in two space dimensions and, hence, can evaluate these effects on simultaneous horizontal and vertical flow. While the model can describe the areal performance of a steamflood (in which case the heat transfer is described in three dimensions), this aspect will not be considered in this paper. Rather, this paper will describe the model in its application to a vertical cross-section through the reservoir and will consider some preliminary investigations to demonstrate the importance of being able to simultaneously account for horizontal and vertical fluid flow. Mathematical details are given in appendices. MATHEMATICAL DESCRIPTION OF STEAMFLOODING Darcy's law provides expressions for the velocities of the three phases (oil, water and gas), which, when combined with oil, water and gas mass balances give the partial differential equations governing Now of the three phases within a reservoir sand: OIL PHASE ..(1) WATER PHASE ..(2) SPEJ P. 405

Study on Alkaline Mass Transfer Regularity with Dissolution in Porous Media

2012 ◽  
Vol 516-517 ◽  
pp. 790-796
Author(s):  
Huai Jun Yang ◽  
Wei Dong Liu ◽  
Hui Hui Kou
Keyword(s):  
Mass Transfer ◽  
Porous Media ◽  
Oil Recovery ◽  
Alkaline Solution ◽  
Concentration Distribution ◽  
Reaction Dynamics ◽  
Solution Concentration ◽  
Reaction Series ◽  
One Dimensional ◽  
Solution Regularity

Inducting dissolution speed constant and multistage reaction series to the alkaline solution transmission equation, this article established the alkaline solution transmission equation with multistage reaction dynamics in the porous media of stratum mineral and calculated one-dimensional alkaline solution concentration distribution. Experimental results verified the correctness of transmission equation, moreover, it further analyzed the alkaline solution regularity in the porous media. The model will be used to predict alkali loss, optimize alkaline solution concentration and slug size, thereby alkaline waterflooding or combination drive can obtain better displacement characteristics and improve the oil recovery.

Mass Transfer Between Phases in a Porous Medium: A Study of Equilibrium

1965 ◽  
Vol 5 (01) ◽  
pp. 51-59 ◽  
Author(s):  
P. Raimondi ◽  
M.A. Torcaso
Keyword(s):  
Mass Transfer ◽  
Porous Media ◽  
Partition Coefficient ◽  
Oil Recovery ◽  
Carrier Phase ◽  
Peak Height ◽  
Lower Velocity ◽  
Immobile Phase ◽  
Two Phases ◽  
Gas Drive

Abstract To study mass transport in systems simulating oil recovery processes, different porous media were saturated with a mobile (carrier phase) and a stationary phase. Slugs of carrier phase containing a small amount of solute were displaced with pure carrier phase. By analogy to the chromatographic processes, the velocity of the solute can be predicted from a knowledge of the partition coefficient and the saturation provided that equilibrium between the two phases exists. Equilibrium was found to exist for different porous media, solutes and rates. The conditions were varied over the range normally encountered in the laboratory and in the field. The longitudinal dispersion of a solute undergoing interphase mass transfer was also investigated. Introduction The production of hydrocarbons by gas cycling, enriched gas drive and CO2 or alcohol displacement involves, among other factors, relative motion between two phases and compounds, hereafter called solute, which are soluble in both phases. The solute is carried forward by the faster flowing phase at a lower velocity than the average velocity of that phase. Retardation of the solute is caused by chromatographic absorption and desorption in the slower flowing phase and by the degree of departure from equilibrium. At equilibrium the concentration of solute in the two phases can be related by the equation* (1) where Csw and Cso are the concentration of solute in the aqueous and oleic phases respectively and K is the equilibrium ratio, or partition coefficient. Displacement theories must contain an explicit assumption with regard to equilibrium, i.e., whether the compositions can be related by Eq. 1. The existance of equilibrium depends, in general on the relative velocity between the phases. Unfortunately, other factors such as gravity segregation and viscous fingering, also depend on velocity. For this reason, whenever effects of rate on displacement were observed, it was practically impossible to discern what caused them - lack of equilibrium or the factors mentioned above. Equilibrium between phases has been the subject of extensive studies in fields such as extraction or chromatography. It has received only small attention in flow through the type of porous media encountered in oil production. For this reason a method was developed which makes it possible to study the movement of a solute as it is affected by rate, type of porous media, partition coefficient and carrier phase, but in the absence of segregation or fingering. The information obtained enables one to determine when the assumption of equilibrium can be made. Briefly, the method consists of (1) saturating the core with a mobile and an immobile phase, (2) injecting a slug made up of the same fluid as the mobile phase and a small concentration of mutually soluble solute, (3) measuring the lag and the peak height of the slug at arrival and (4) correlating these variables with fluid properties such as partition coefficient and mixing constants of the medium. PROPOSED MECHANISM The principles of chromatography are combined with the equation of longitudinal mixing to predict the velocity of a solute slug compared to the bulk velocity and the peak height of a slug. The equation so obtained is valid under equilibrium conditions only. Therefore, a comparison between experimental and predicted results will give a measure of departure from equilibrium. This work was done with either the oleic or the aqueous phase being immobile. For simplicity, the following development is based on the case where the oleic phase is immobile. However, the treatment is the same in either case. SPEC P. 51ˆ

Tertiary Surfactant Flooding: Petroleum Sulfonate Composition-Efficacy Studies

1973 ◽  
Vol 13 (04) ◽  
pp. 191-199 ◽  
Author(s):  
Walter W. Gale ◽  
Erik I. Sandvik
Keyword(s):  
Interfacial Tension ◽  
Oil Recovery ◽  
Weight Distribution ◽  
Capillary Rise ◽  
Equivalent Weight ◽  
Residual Oil ◽  
Surfactant Flooding ◽  
Petroleum Sulfonate ◽  
Low Interfacial Tension ◽  
Oil Water

Abstract This paper discusses results of a laboratory program undertaken to define optimum petroleum program undertaken to define optimum petroleum sulfonates for use in surfactant flooding. Many refinery feedstocks, varying in molecular weight and aromatic content, were sulfonated using different processes, Resulting sulfonates were evaluated by measuring interracial tensions, adsorption-fractionation behavior, brine compatability, and oil recovery characteristics, as well as by estimating potential manufacturing costs. The best combination o[ these properties is achieved when highly aromatic feedstocks are sulfonated to yield surfactants having very broad equivalent weight distributions. Components of the high end of the equivalent weight distribution make an essential contribution to interfacial tension depression. This portion is also strongly adsorbed on mineral surfaces and has low water solubility. Middle Portions of the equivalent weight distribution serve as sacrificial adsorbates while lower equivalent weight components Junction as micellar solubilizers for heavy constituents. Results from linear laboratory oil-recovery tests demonstrate interactions of various portions of the equivalent weight distribution. portions of the equivalent weight distribution Introduction Four major criteria used in selecting a surfactant for a tertiary oil-recovery process are:low oil-water interfacial tension,low adsorption,compatibility with reservoir fluids andlow cost. Low interfacial tension reduces capillary forces trapping residual oil in porous media allowing the oil to be recovered. Attraction of surfactant to oil-water interfaces permits reduction of interfacial tension; however, attraction to rock-water interfaces can result in loss of surfactant to rock surfaces by adsorption. Surfactant losses can also arise from precipitation due to incompatibility with reservoir fluids. Low adsorption and low cost are primarily economic considerations, whereas low interfacial tension and compatibility are necessary for workability of the process itself. Petroleum sulfonates useful in surfactant flooding have been disclosed in several patents; however, virtually no detailed information is available in the nonpatent technical literature. Laboratory evaluation of surfactants consisted of determining their adsorption, interfacial tension, and oil recovery properties. Adsorption measurements were made by static equilibration of surfactant solutions with crushed rock and clays and by flowing surfactant solutions through various types of cores. Interfacial tensions were measured using pendant drop and capillary rise techniques. Berea, pendant drop and capillary rise techniques. Berea, Bartlesville, and in some cases, field cores containing brine and residual oil were flooded with sulfonate solutions in order to determine oil recovery. Fluids used in these displacement tests are described in Table 1. Unless otherwise specified, displacements of Borregos crude oil were carried out with Catahoula water as the resident aqueous phase after waterflooding and displacements of phase after waterflooding and displacements of Loudon crude oil with 1.5 percent NaCl as the resident aqueous phase. In those examples where banks of surfactants were injected, drive water following the surfactant had the same composition as the resident water. Concentrations of sulfonates are reported on a 100-percent activity basis. PETROLEUM SULFONATE CHEMISTRY PETROLEUM SULFONATE CHEMISTRY A substantial portion of the total research effort TABLE 1 - PROPERTIES OF FLUIDS USEDIN FLOODING TESTS

An Analytical Model for One-Dimensional, Three-Component Condensing and Vaporizing Gas Drives

1984 ◽  
Vol 24 (02) ◽  
pp. 169-179 ◽  
Author(s):  
J.M. Dumore ◽  
J. Hagoort ◽  
A.S. Risseeuw
Keyword(s):  
Mass Transfer ◽  
Phase Behavior ◽  
Gas Phase ◽  
Method Of Characteristics ◽  
Numerical Approach ◽  
Surfactant Flooding ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
Multicomponent Gas ◽  
Sharp Fronts

Abstract An analytical model based on the method of characteristics is presented for the calculation of one- dimensional (1D), three-component condensing and vaporizing gas dives. The model describes (1) mass transfer between oil and gas, (2) swelling and shrinkage, (3) viscosity and density changes, (4) gravity stabilization, and (5) rock/fluid interaction. The main assumptions of the model are local thermodynamic equilibrium and the absence of dispersion, diffusion, and capillarity. Example calculations are presented that bring out the main features of both condensing and vaporizing gas drives and also indicate the importance of mass transfer between the phases. In the special case of "developed miscibility," the model predicts a piston-like displacement having a complete recovery at gas breakthrough. The main applications of the model are in (1) conceptual studies of gas drives in which mass transfer plays an important role and (2) the calibration and checking of numerical reservoir simulators for multicomponent, multiphase flow. Introduction Gas injection is increasingly being applied as a secondary or tertiary recovery technique. In many applications injection gas is not directly miscible and is not in thermodynamic equilibrium with reservoir oil. As a consequence, component transfer takes place between gas and oil, which has a direct bearing on the displacement efficiency of the gas-injection process. Depending on the component transfer, two different processes are commonly distinguished: condensing and vaporizing gas drives. In condensing gas drives, the composition of the gas phase becomes progressively leaner on contact with the reservoir oil; the heavier components in the injection gas "condense" in the oil phase. Condensing gas drives occur when relatively rich gas is injected and are therefore called "rich" or "enriched" gas drives. In vaporizing gas drives, the reverse process occurs: the gas phase becomes progressively richer owing to vaporization of the middle components of the reservoir oil. Vaporizing gas drives occur when relatively lean gas is injected and are therefore called "lean" gas drives. A mechanistic understanding of oil displacement by immiscible, nonequilibrium gases is no simple matter. In these processes the flow of the two phases--gas and oil--is strongly influenced by the phase behavior of the multicomponent gas/oil mixture. This is compounded by the nonconstant physical properties of gas and oil resulting from compositional changes during the displacement. To investigate multicomponent gas drives theoretically, two approaches can be taken. First, the numerical approach: the basic differential equations are directly cast in a difference form and subsequently solved. In principle, this approach can handle many components and three dimensions. The drawback of the numerical approach is that possible sharp fronts are smeared out by numerical dispersion, which may obscure the results and make interpretation rather difficult. The second approach is the analytical one: the basic differential equations are simplified such that they become amenable to analytical mathematical analysis, notably the method of characteristics. This approach is less versatile in that it generally will be restricted to one dimension and a small number of components. Analytical models, however, are very helpful in obtaining a mechanistic understanding of the process. In addition, these models can accommodate sharp fronts and can therefore be used to calibrate and check numerical models. The first successful attempt to describe the coupling of two-phase flow and phase behavior in gas drives analytically was made by Welge et al. They investigated a 1D, three-component condensing gas drive and developed a calculation method essentially based on the method of characteristics. The problem of coupled multiphase flow and phase behavior also occurs in alcohol and surfactant flooding. Here the problems also can be formulated such that they can be solved by the method of characteristics. Wachmann presented a theory for alcohol flooding along these lines. Larson and Hirasaki and Larson applied the theory of characteristics to surfactant flooding. Recently Helfferich presented a general theory on 1D multiphase, multicomponent fluid flow in porous media. based on concepts developed in the area of theoretical multicomponent chromatography. Hirasaki applied these concepts to surfactant flooding. SPEJ P. 169^

scholarly journals Main Controlling Factor of Polymer-Surfactant Flooding to Improve Recovery in Heterogeneous Reservoir

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Dandan Yin ◽  
Dongfeng Zhao
Keyword(s):  
Oil Recovery ◽  
Surfactant Concentration ◽  
Shear Resistance ◽  
Controlling Factors ◽  
Chemical Agent ◽  
High Shear ◽  
Surfactant Flooding ◽  
Heterogeneous Reservoir ◽  
Oil Water ◽  
Polymer Surfactant

This study aims to analyze the influence of viscosity and interfacial tension (IFT) on the recovery in heterogeneous reservoir and determines the main controlling factors of the polymer-surfactant (SP) flooding. The influence of the salinity and shearing action on the polymer viscosity and effects of the surfactant concentration on the IFT and emulsion behavior between chemical agent and oil were studied through the static and flooding experiments. The results show that increasing the concentration of polymer GF-11 (HPAM) can reduce the influence of the salinity and GF-11 has high shear-resistance property. In the condition of the Jilin Oilfield, the oil/water IFT can reach 10−3 mN/m when the surfactant concentration is 0.3 wt%. The lower the IFT is, the easier the emulsion of SP and oil is formed. Seven flooding experiments are conducted with the SP system. The results show that the recovery can be improved for 5.02%–15.98% under the synergistic effect of the polymer and surfactant. In the heterogeneous reservoir, the contribution of oil recovery is less than that of the sweep volume.

scholarly journals Mechanism of active silica nanofluids based on interface-regulated effect during spontaneous imbibition

2021 ◽  
Author(s):  
Xu-Guang Song ◽  
Ming-Wei Zhao ◽  
Cai-Li Dai ◽  
Xin-Ke Wang ◽  
Wen-Jiao Lv
Keyword(s):  
Contact Angle ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Dynamic Contact Angle ◽  
Liquid Interface ◽  
Spontaneous Imbibition ◽  
Wettability Alteration ◽  
Low Permeability ◽  
Oil Water ◽  
Solid Liquid

AbstractThe ultra-low permeability reservoir is regarded as an important energy source for oil and gas resource development and is attracting more and more attention. In this work, the active silica nanofluids were prepared by modified active silica nanoparticles and surfactant BSSB-12. The dispersion stability tests showed that the hydraulic radius of nanofluids was 58.59 nm and the zeta potential was − 48.39 mV. The active nanofluids can simultaneously regulate liquid–liquid interface and solid–liquid interface. The nanofluids can reduce the oil/water interfacial tension (IFT) from 23.5 to 6.7 mN/m, and the oil/water/solid contact angle was altered from 42° to 145°. The spontaneous imbibition tests showed that the oil recovery of 0.1 wt% active nanofluids was 20.5% and 8.5% higher than that of 3 wt% NaCl solution and 0.1 wt% BSSB-12 solution. Finally, the effects of nanofluids on dynamic contact angle, dynamic interfacial tension and moduli were studied from the adsorption behavior of nanofluids at solid–liquid and liquid–liquid interface. The oil detaching and transporting are completed by synergistic effect of wettability alteration and interfacial tension reduction. The findings of this study can help in better understanding of active nanofluids for EOR in ultra-low permeability reservoirs.

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