Cosurfactants in Micellar Systems Used for Tertiary Oil Recovery

1976 ◽  
Vol 16 (03) ◽  
pp. 161-167 ◽  
Author(s):  
S.C. Jones ◽  
K.D. Dreher
Keyword(s):  
Physicochemical Properties ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Electrolyte Concentration ◽  
Weight Percent ◽  
Reservoir Rock ◽  
Equivalent Weight ◽  
Petroleum Sulfonate ◽  
Micellar Systems

Abstract The influence of alcohols used as cosurfactants on several micellar systems was investigated. These alcohols modify phase behavior and control the amount of brine or hydrocarbon that a microemulsion can "solubilize." Also, viscosity can be adjusted using the right cosurfactant for mobility control. Relationships between cosurfactant concentration and electrolyte concentration, hydrocarbon type, or temperature are presented. Introduction Micellar slugs used as oil-displacing agents in extra-oil recovery projects are usually composed of surfactant(s), hydrocarbon, water, electrolyte, and one or more alcohols that serve as cosurfactants. Physicochemical properties of these systems have Physicochemical properties of these systems have been presented by several authors; phase behavior has received special attention. Such emphasis is justified because of displacement-mechanism considerations and micellar-slug deterioration by reservoir rock and fluids. Other work has been concerned with defining the role of particular sulfonates in oil displacement and loss of surfactant to reservoir rock. Healy et al. presented detailed analyses of a single surfactant/cosurfactant combination in micellar systems and laboratory oil recovery experiments. Papers have presented qualitative information on the role of cosurfactants. Gogarty and Tosch found that the amount of 2-propanol (IPA) required to produce phase-stable systems depended on produce phase-stable systems depended on hydrocarbon type. They and others reported that IPA makes a micellar slug more compatible with reservoir brines, whereas oil-soluble alcohols enhance compatibility with crude oils. Cosurfactants have various effects on viscosity; IPA usually causes a reduction. Healy and Reed noted a decrease in viscosity upon addition of tertiary amyl alcohol (TAA). For the system examined, TAA increases the size of the water-external region in the ternary phase diagram. Others have reported that cosurfactants increase water solubility of sulfonates and reduce adsorption on reservoir rock. Although cosurfactants have been shown to perform a variety of functions, no systematic quantitative study of their effect on physicochemical properties of micellar systems has appeared in the petroleum literature. This paper will show how cosurfactants affect phase behavior, control hydrocarbon and brine solubility, interact with electrolyte concentration, and change viscosity and electrical conductivity. Systems examined include a low-water-concentration, oil-external microemulsion; a water-external microemulsion; and "intermediate" systems for which the continuous phase is not clearly defined. Each type of micellar system has been tested in field applications of the Maraflood oil recovery process. process. MATERIALS AND METHODS Compositions of the six micellar systems studied are shown in Table 1, which also indicates the source and equivalent weight of the petroleum sulfonate surfactants used. Table 2 lists information about the alcohols used as cosurfactants. Viscosities were measured at 72 deg. F and at 3 or 6 rpm with a Brookfield Model LVT viscometer equipped with a UL adaptor. Shear rates at this speed are about 5 to 10 sec-1. All phase-behavior experiments were performed at 72 deg. F, with the exception of the relationships shown in Fig. 11. Systems were observed for a minimum of 24 hours. PHASE BEHAVIOR WITH ALCOHOL PHASE BEHAVIOR WITH ALCOHOL Alcohols as cosurfactants modify the phase behavior of a brine-hydrocarbon-surfactant micellar system. For example, Composition A in Table 1, composed of an oleophilic surfactant (470-equivalent-weight petroleum sulfonate), 28-weight-percent water, petroleum sulfonate), 28-weight-percent water, and hydrocarbon (light, straight run gasoline), separates into an aqueous phase in equilibrium with a microemulsion phase. SPEJ P. 161

Adsorption/Retention of Petroleum Sulfonates in Berea Cores

1977 ◽  
Vol 17 (05) ◽  
pp. 353-357 ◽  
Author(s):  
J.H. Bae ◽  
C.B. Petrick
Keyword(s):  
Adsorption Isotherm ◽  
Aqueous Solutions ◽  
Flow Rate ◽  
Oil Recovery ◽  
Reservoir Rock ◽  
Equivalent Weight ◽  
Flow Rates ◽  
The Core ◽  
Petroleum Sulfonate ◽  
Pass Through

Abstract A series of petroleum sulfonate adsorption experiments was conducted in 2-in.-diameter, 2-ft-long Berea cores initially saturated with 1-percent NaCl brine. The sulfonates used had an average equivalent weight of 430 with a broad equivalent-weight distribution. The concentration ranged from 0.01 to 8 per cent. The flow rates investigated ranged from 2 to 36 ft/D. Adsorption was determined either from analysis of the effluent concentrations or by extraction of sulfonates from the core. The physical properties of the solutions were also measured. In several tests, Na2CO3 was used as a sacrificial chemical, either in a preflood or added to the sulfonate solution. It was found that at certain concentrations, apparent adsorption is dependent on the flow rate. The sulfonate adsorption isotherm was found to pass through a maximum. The value of the pass through a maximum. The value of the adsorption maximum and the concentration at which it occurs are also dependent on the flow rate. The time required for adsorption equilibrium was found to increase with increasing sulfonate concentration. A sacrificial chemical reduced the sulfonate adsorption. However, sulfonate adsorption increased gradually with time. Adsorption tests should be conducted at realistic flow rates. Introduction One of the major problems in surfactant flooding is the adsorption of surfactants on the reservoir rock. If adsorption is excessive, surfactants are depleted rapidly from the slug as it moves through the reservoir; consequently, it loses the ability to lower the oil-water interfacial tension. Thus, the magnitude of adsorption is an important technical as well as economic parameter. It has been reported that the adsorption of petroleum sulfonates is selective. The high-equivalent-weight sulfonates are adsorbed preferentially whole low-equivalent-weight preferentially whole low-equivalent-weight sulfonates show almost no adsorption. Most of the adsorbed sulfonates had an equivalent weight of 500 or more. This type of fractionation was considered to be the main cause for poor oil recovery in a field pilot test. The literature data on the adsorption of petroleum sulfonates from aqueous solutions indicate petroleum sulfonates from aqueous solutions indicate that there is a maximum in the adsorption isotherm. Furthermore, the adsorption of sulfonate is reduced significantly when sacrificial chemicals are used. The experimental methods used in these measurements differ from one another and, on occasion, the adsorbed sulfonates are defined to be the amount extracted by a solvent after a brine flush. The term "adsorption" is used here rather loosely. Some people prefer the term retention to adsorption since there may be physical retention in a core. The physical retention may or may not exist in a given experiment and detection of it may be very difficult. The objective of this work is to investigate the adsorption phenomenon in dynamic core tests. Several questions are examined: How is the adsorption isotherm related to the general properties of the solution? Do the dynamic test conditions affect the adsorption measurement? Are sacrificial chemicals useful in reducing sulfonate adsorption? EXPERIMENTAL PROCEDURES The petroleum sulfonate used was a blend of sulfonates, TRS 18 and TRS 40 obtained from Witco Chemical Co., and has an average equivalent weight of 430. The equivalent weight ranged from 250 to 650, with about 80 percent ranging from 350 to 550, almost evenly distributed. Isopropyl alcohol was used as a cosolvent at 1/10 of the sulfonate concentration. A 1-percent NaCl brine was used as the aqueous medium. Weight percentage is used throughout this paper. All adsorption tests were conducted at room temperature of 72 degrees F in 2-in.-diameter, 2-ft-long Berea cores saturated with brine. The permeability to brine in all tests was 450 + 25 md. The sulfonate solution was injected continuously into the cores using a positive-displacement pump. The produced fluids were collected in a fraction collector. In most cases, at the end of sulfonate injection, the sulfonate in the core was extracted immediately with a methanol-chloroform mixture. SPEJ P. 353

Dynamic Interfacial Tension Behavior of Pure and Binary Surfactant System

2020 ◽  
Vol 17 (2) ◽  
pp. 1251-1259
Author(s):  
Nur Asyraf Md Akhir ◽  
Ismail Mohd Saaid ◽  
Ahmad Kamal Idris ◽  
Anita Ramli ◽  
Nurul Amirah Ismail ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Physicochemical Properties ◽  
Oil Recovery ◽  
Liquid Crystalline ◽  
Reservoir Rock ◽  
Wettability Alteration ◽  
Pure System ◽  
Dynamic Interfacial Tension ◽  
Surfactant System ◽  
Internal Olefin Sulfonate

Surfactants are very important surface-active agents in implementation of chemical enhanced oil recovery for oil-water interfacial tension and wettability alteration. However, the high adsorption of surfactant on reservoir rock reduces the efficiency of surfactant flooding. Conventionally, inorganic alkali has been introduced to reduce adsorption of surfactant, but alkali will lead to the formation of emulsion, formation damage and scaling. Therefore, lignosulfonate, a sacrificial agent has been introduced as an alternative to inorganic alkali. In this paper, the critical micelle concentration (CMC) and dynamic interfacial tension (IFT) behavior of a pure and binary system of internal olefin sulfonate (IOS) and lignosulfonate (LS) at brine-decane interfaces are determined by using a spinning drop method. The physicochemical properties of pure and binary of IOS and LS system are determined by conductivity and pH measurements. The CMC value of IOS in 3.5 wt% brine salinity is higher compared to LS due to the isomeric branched of IOS which can occupy a larger area per molecules. The dynamic interfacial tension of IOS shows the fast adsorption of surfactant molecules to the brine-decane interfaces. This is indicated by the fast equilibrium interfacial tension reached by IOS. In comparison, the LS pure system shows decreasing behavior of dynamic interfacial tension. The fast adsorption at the interfaces is only reached for higher LS concentrations. The synergy effect between IOS and LS system shows a reduction in the interfacial value with LS optimum concentration of 0.6 wt%. The drop in conductivity and pH values indicated the development of a tightly packed lamellar liquid crystalline structure. These physicochemical properties are in agreement with the dynamic interfacial tension behavior of the IOS and LS system. This study has demonstrated the significant impact of the LS addition in reducing the dynamic interfacial tension of the surfactant system.

Phase Behavior and Properties of a Petroleum Sulfonate Blend

1981 ◽  
Vol 21 (05) ◽  
pp. 573-580 ◽  
Author(s):  
J.H. Bae ◽  
C.B. Petrick
Keyword(s):  
Interfacial Tension ◽  
Crude Oil ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Surfactant Solution ◽  
Phase Region ◽  
Salinity Range ◽  
Equal Weight ◽  
Optimal Salinity ◽  
Petroleum Sulfonate

Abstract A sulfonate system composed of Stepan Petrostep TM 465, Petrostep 420, and 1-pentanol was investigated. The system was found to give ultralow interfacial tension against crude oil in a reasonable range of salinity and sulfonate concentrations. It also was found that sulfonate partitioned predominantly into the microemulsion phase. However, a significant amount also partitioned into water and, at high salinity, into the oil phase. On the other hand, the oil-soluble 1-pentanol partitioned mostly into oil and microemulsion phases.The interfacial tension between excess oil and water phases was ultralow, in the range of 10-3 mN/m. The tensions were close to and paralleled those between the middle and water phases. The trend remained the same even when the alcohol content changed. This means that in the salinity range that produces a three-phase region, below the optimal salinity, the water phase effectively displaces both oil and middle phases, even though the oil may not be displaced effectively by the middle phase. The implication is that, from an interfacial tension point of view, the oil recovery would be more favorable in the salinity range below the optimal salinity with the mixed petroleum sulfonate system used here. This was confirmed by oil recovery tests in Berea cores. It also was concluded that the change in viscosity upon microemulsion formation might have a significant influence on the surfactant flood performance. Introduction During a surfactant flood, the injected slug of surfactant solution undergoes complex changes as it traverses the reservoir. The surfactant solution is diluted by mixing with reservoir oil and brine and by depletion of surfactant due to retention. Also, the reservoir salinity rarely is the same as that of the injected solution. Moreover, there is chromatographic separation of sulfonate and cosurfactant.When phase equilibrium between oil, brine, and injected surfactant is reached in the front portion of the slug, a microemulsion phase is formed. This phase behavior and its importance in oil recovery have been the subject of numerous papers in recent years. The microemulsion phase formed in the reservoir contacts fresh reservoir brine and oil and undergoes further changes. All these changes are accompanied by property changes of the phases that affect oil recovery.The objective of this paper is to investigate the properties of a blend of commercial petroleum sulfonates and its behavior in different environments. The phase volume behavior and changes in the properties of different phases and their effects on oil recovery were studied. This work was done as part of the design of a surfactant process for a field application. Therefore, a crude oil was used as the hydrocarbon phase. Experimental Procedures A blend of Petrostep 465 and 420 from Stepan Chemical Co. was used as the surfactant. An equal weight of each sulfonate on a 100% active basis was mixed. 1-pentanol from Union Carbide Corp. was used as a cosurfactant. Unless otherwise stated, a 50g/kg sulfonate concentration was used in the solution. We used symbols to denote the formulation. The first number in the symbol indicates the 1-pentanol concentration; the last number indicates the NaCl concentration. Thus, 15 P 10 means that the solution consists of 50 g/kg sulfonate, 15 g/kg 1-pentanol, and 10 g/kg NaCl. The sulfonate blend first was mixed with alcohol, and then the required amount of NaCl brine was added to make the solution. SPEJ P. 573^

Experimental Investigation of Water Incompatibility and Rock/Fluid and Fluid/Fluid Interactions in the Absence and Presence of Scale Inhibitors

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2615-2631 ◽  
Author(s):  
Mehdi Mohammadi ◽  
Siavash Riahi
Keyword(s):  
Phase Behavior ◽  
Oil Recovery ◽  
Water System ◽  
Contact Angles ◽  
Reservoir Rock ◽  
Wettability Alteration ◽  
Environmental Scanning ◽  
Interfacial Behavior ◽  
Behavior Study ◽  
Fluid Interactions

Summary Waterflooding is known as an affordable method to enhance oil recovery after primary depletion. However, the chemical incompatibility between injected water and the water in the reservoir may cause the formation of mineral scales. The most effective method for managing such a problem is to use a variety of scale inhibitors (SIs) along with a waterflooding plan. It is necessary to perform a comprehensive study on the incompatibility scaling issue for the candidate-brine/SI formulations, and also their effect on the reservoir-rock/fluid characteristics. In this study, both in the absence and presence of polymeric, phosphonate, and polyphosphonate SIs, the scaling tendency (ST) of different brines is evaluated through experimental and simulation works. Drop-shape analysis (DSA), environmental-scanning-electronic-microscopy (ESEM) observation, energy-dispersive X-ray (EDX) analysis, and microemulsion phase behavior are also used to study the effect of different brine/SI formulations on the rock/fluid and fluid/fluid interactions, through wettability and interfacial-tension (IFT) evaluation. In summary, sulfate (SO42−) was identified as the most problematic ion in the formulation of injected water that causes the formation of solid scales upon mixing with the cation-rich formation water (FW). In the case of SIs, solid precipitation was shifted toward a lower value, with more pronounced effects at higher SI concentrations. At different ionic compositions, the inhibition efficiency (IE%) of all SIs ranged from 16 to 50% at [SI]  = 20 ppm and 38 to 81% at [SI] = 50 ppm. In general, phosphonates worked better (i.e., higher IE value) than polymeric SI. Measuring contact angles along with ESEM/EDX data also illustrated the positive effect of SIs on the wettability alteration of the aged carbonate substrates. In the absence of SIs, the contact angles for different brines were in the range of 70° ≤ θ ≤ 104°, whereas these values fell between 35 and 80° for systems containing 50 ppm of SI. In addition, phase-behavior study and IFT measurement illustrated a salinity-dependence effect of SIs on the interfacial behavior of the oil/water system.

Advantages of an APS/AES Seawater-Based Surfactant Polymer Formulation

SPE Journal ◽  
2020 ◽  
Vol 25 (06) ◽  
pp. 3494-3506
Author(s):  
Jeffrey G. Southwick ◽  
Carl van Rijn ◽  
Esther van den Pol ◽  
Diederik van Batenburg ◽  
Arif Azhan ◽  
...  
Keyword(s):  
Crude Oil ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Salinity Gradient ◽  
Low Complexity ◽  
Fine Tuning ◽  
Reservoir Rock ◽  
Similar Amount ◽  
Type I ◽  
Chemical Flooding

Summary A low-complexity chemical flooding formulation has been developed for application in offshore environments. The formulation uses seawater with no additional water treatment beyond that which is normally performed for waterflooding (filtration, deoxygenation, etc.). The formulation is a mixture of an alkyl propoxy sulfate (APS) and an alkyl ethoxy sulfate (AES) with no cosolvent. With seawater only (no salinity gradient), the blend of APS and AES gives substantially higher oil recovery than a blend of APS and internal olefin sulfonate (IOS) in outcrop sandstone. This formulation also reduces complexity, increases robustness, and potentially improves project economics for onshore projects as well. It is shown that the highest oil recovery is obtained with surfactant blends that produce formulations that are underoptimum (Winsor Type I phase behavior) with reservoir crude oil. Also, these underoptimum formulations avoid the high-injection pressures that are seen with optimum formulations in low-permeability outcrop rock. The formulation recovers a similar amount of oil in reservoir rock in the swept zone. Overall recovery in reservoir rock is lower than outcrop sandstone due to greater heterogeneity, which causes bypassing of crude oil. A successful formulation was developed by first screening surfactants for phase behavior then fine tuning the formulation based on insights developed with corefloods in consistent outcrop rocks. The consistency of the outcrop is essential to understand cause and effect. Then, final floods were performed in reservoir rock to confirm that low interfacial tension (IFT) is propagated through the core.

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

The Effect of Ethoxylated Sulfonates on Salt Tolerance and Optimal Salinity of Surfactant Formulations for Tertiary Oil Recovery

1978 ◽  
Vol 18 (03) ◽  
pp. 167-172 ◽  
Author(s):  
V.K. Bansal ◽  
D.O. Shah
Keyword(s):  
Salt Tolerance ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Surfactant Concentration ◽  
Weight Percent ◽  
Mixed Surfactant ◽  
Optimal Salinity ◽  
Petroleum Sulfonate ◽  
Ethoxylated Alcohols ◽  
Tertiary Oil Recovery

Abstract The addition of an ethoxylated sulfonate (EOR-200) and its effect on the salt tolerance and optimal salinity of formulations containing a petroleum sulfonate (TRS 10-410 or Petrostep-465) petroleum sulfonate (TRS 10-410 or Petrostep-465) and an alcohol was investigated. When salt concentration increases, the mixed surfactant formulations undergo the following changes: isotropic, birefringent, phase separation. The salt concentration required for phase separation increased with the fraction of the ethoxylated sulfonate in the formulation. When mixed surfactant formulations were equilibrated with an equal volume of oil (decane or hexadecane) a middle-phase microemulsion formed in a specific salinity range. The optimal salinity increased with the fraction of the ethoxylated sulfonate in the mixed surfactant formulations. At optimal salinity as high as 32-percent NaCl, these surfactant formulations exhibited ultra-low interfacial tension (10-2 to 10-3 dynes/cm). These formulations also showed that an increase in the solubilization parameter decreases the interfacial tension. parameter decreases the interfacial tension Introduction The potential use of petroleum sulfonates for tertiary oil recovery has been discussed and several patents have been issued during the past two decades. The solubilization, phase behavior and interfacial tension of petroleum sulfonates have been studied. Petroleum sulfonates are known to exhibit relatively low salt tolerance and a low value of optimal salinity (1- to 2-percent NACl). Dauben and Froning studied the effect of Amoco Wellaid 320 (ethoxylated alcohol) on a surfactant formulation that was primarily a petroleum sulfonate. They observed that surfactant formulations prepared using ethoxylated alcohols as cosurfactants exhibited improved temperature stability and were less sensitive to salts, compared with formulations prepared with isopropanol as a cosurfactant. Several prepared with isopropanol as a cosurfactant. Several patents were issued on the possible use of patents were issued on the possible use of ethoxylated alcohols and ethoxylated sulfonates in oil recovery formulations. This study reports the effect of blending an ethoxylated sulfonate (EOR-200) with a petroleum sulfonate (TRS 10-410 or Petrostep-465) on various properties of the mixed surfactant formulations (for properties of the mixed surfactant formulations (for examples, salt tolerance, optimal salinity, interfacial tension, and solubilization). MATERIALS AND METHODS Petroleum sulfonates TRS 10-410 and Petrostep-465 were supplied by Witco Chemicals and Stepan Petrostep-465 were supplied by Witco Chemicals and Stepan Chemicals, respectively. Ethoxylated sulfonate EOR-200 was supplied by Ethyl Corp. Paraffinic oils (n-hexadecane and n-decane) as well as 99-percent pure isobutanol and n-pentanol were purchased from Chemicals Samples Co. All purchased from Chemicals Samples Co. All surfactants were used as received. The average equivalent weight of TRS 10-410 and Petrostep-465 was 420 and 465, respectively, and the activity of surfactants was approximately 60 percent (as reported by the manufacturers). The molecular weight of EOR-200 was given as 523 by Ethyl and the sample contained 25.3 weight percent active solid surfactant. Aqueous solutions composed of Petrostep-465 (5 percent) and n-pentanol (2 percent) were prepared on the basis of weight. Aqueous surfactant solutions were equilibrated with the same volume of n-decane. Optimal salinity values were obtained using the approach described by Healy and Reed. The effect of EOR-200 on the properties of mixed surfactant formulations was studied by gradually replacing Petrostep-465 with EOR-200 and keeping the total surfactant concentration constant at 5 weight percent. Another surfactant formulation studied was composed of TRS 10-410 (5 percent) and IBA (3 percent). Optimal salinity was determined using percent). Optimal salinity was determined using n-hexadecane. TRS 10-410 was replaced gradually by EOR-200, keeping the total surfactant concentration constant at 5 weight percent. The systems studied are tabulated in Table 1. SPEJ P. 167

Experimental Study of Polymer Flooding in Fractured Systems Using Five-Spot Glass Micromodel: The Role of Fracture Geometrical Properties

2012 ◽  
Vol 30 (5) ◽  
pp. 689-705 ◽  
Author(s):  
Behbood Abedi ◽  
Mohammad Hossein Ghazanfari ◽  
Riyaz Kharrat
Keyword(s):  
Oil Recovery ◽  
Polymer Flooding ◽  
Recovery Factor ◽  
Reservoir Rock ◽  
Water Flooding ◽  
Recovery Method ◽  
Geometrical Properties ◽  
Fracture Orientation ◽  
Glass Micromodel

Water flooding is being widely used in the petroleum industry and has been considered as a simple inexpensive secondary recovery method. But in fractured formations, existence of fracture system in reservoir rock induces an adverse effect on oil recovery by water flooding. Polymer flooding has been successfully applied as an alternative enhanced oil recovery method in fractured formations. But, the role of fracture geometrical properties on macroscopic efficiency of polymer flooding is not yet well-understood, especially in fractured five-spot systems. In this work five-spot glass micromodel, because of micro-visibility, ease of multiple experimentations and also presence of the unexplored issues, was used to experimentally investigate the influence of fracture geometrical characteristics such as fracture orientation, fracture spacing, fracture overlap and etc on the macroscopic efficiency of polymer flooding. The tests were performed on the fractured models which are initially saturated with the crude oil at fixed flow rate conditions and in a horizontally mounting. The results revealed that the macroscopic efficiency of polymer flooding depends on fracture geometrical properties. Fracture orientation showed more imposing effect than other fracture geometrical properties, and fracture with 45 degree inclination to the mean flow direction, gives greatest oil recovery factor. Large spacing fractures give more recovery than small spacing ones and in case of overlapping, fractures with less overlapping help polymer to better propagate which could be related to their greater effective fracture length. This pre-called effect could be responsible to show how continuity and width to length ratio of fractures affect recovery factor, less fracture discontinuity as well as more length to width ratio of fracture give more swept zone. Also, increasing number of fractures decreases oil recovery factor. The results of this work can be helpful to better understanding the role of fracture geometrical properties on macroscopic efficiency of polymer flooding in five-spot fractured systems.

Multiphase Microemulsion Systems

1976 ◽  
Vol 16 (03) ◽  
pp. 147-160 ◽  
Author(s):  
R.N. Healy ◽  
R.L. Reed ◽  
D.G. Stenmark
Keyword(s):  
Interfacial Tension ◽  
Physicochemical Properties ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Displacement Efficiency ◽  
Oil Composition ◽  
Alkyl Aryl ◽  
Optimal Salinity ◽  
Interfacial Tensions ◽  
Multiphase Behavior

Abstract Economical microemulsion flooding inevitably involves microemulsion phases immiscible with oil or water, or both; oil recovery is largely affected by displacement efficiency during the immiscible regime. Therefore, it is essential to understand the role of interfacial tension in relation to multiphase microemulsion behavior. Three basic types of multiphase systems are identified and used to label phase transitions that occur when changes are made in salinity, temperature, oil composition, surfactant structure, cosolvent, and dissolved solids in the aqueous phase. Directional effects of these changes on phase behavior, interfacial tension, and solubilization parameter are tabulated for the alkyl aryl sufonates studied. A relationship between interfacial tension and phase behavior is established. This provides the phase behavior is established. This provides the basis for a convenient method for preliminary screening of surfactants for oil recovery. Interfacial tensions were found to correlate with the solubilization parameter for the various microemulsion phases, a result that can substantially reduce the number of interfacial tensions that must be determined experimentally for a given application. Introduction A previous paper established that microemulsion flooding is a locally miscible process until slug breakdown and is an immiscible, rate-dependent displacement thereafter; furthermore, for an effective flood, most of the oil recovered is acquired during the immiscible regime. An extensive study of single-phase regions defined classes of micellar structures for a particular surfactant; however, it was subsequently shown these did not affect oil recovery, provided viscous, lamellar structures were avoided. Optimal salinity was introduced as defining a ternary diagram having the least extensive multiphase region, a desirable feature in that locally miscible displacement is prolonged. Immiscible displacement after slug breakdown is known to depend on interfacial tension through its inclusion in the capillary number. A brief study showed chat interfacial tension varied widely throughout the multiphase region; accordingly, it is anticipated that oil recovery will depend on details of multiphase behavior in relation to interfacial tension, as well as on injection composition. Consider a flood sufficiently advanced that the microemulsion slug has broken down. A microemulsion phase remains that is immiscible with water or oil, phase remains that is immiscible with water or oil, or both, and displacement has assumed an immiscible character. The problem is twofold: to design a microemulsion slug that effectively displaces oil at the front and that is effectively displaced by water at the back. Both aspects are essential and, therefore, both microemulsion-oil and microemulsion-water interfacial tensions must be very low. The condition where these two tensions are low and equal will be of particular significance. The purpose of this paper is to explore physicochemical properties of multiphase physicochemical properties of multiphase microemulsion systems with a view toward understanding immiscible aspects of microemulsion flooding, and with the expectation of developing systematic screening procedures useful for design of optimal floods. Equilibration is an essential part of this study. Even the simplest of these systems is so complex it may well happen that nonequilibrium effects will never be understood sufficiently to be usefully accommodated in mathematical simulation of microemulsion flooding. In any event, equilibration, although time consuming, leads to a coherent picture of multiphase behavior that can be correlated with flooding results. Multiphase behavior of "simple" ternary systems divides into three basic classes. Dependence of phase behavior on salinity, with respect to these phase behavior on salinity, with respect to these classes, leads to correlations of interfacial tension with the solubilization parameter. These correlations are studied in relation to surfactant structure, temperature, cosolvents, oil composition, and brine composition. Optimal salinity again plays an important role, especially in relation to interfacial tension. SPEJ P. 147

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