Surfactant for enhanced oil recovery

Subsequent studies and applications with ether carboxylates have been published [73]. Phase inversion temperature measurements, which can be used to select surfactants for enhanced oil recovery, showed good results when the phase inversion temperature of the system was just below the reservoir temperature [184]. 

The use of AOS and other surfactants as steam-foaming agents has been studied by several oil companies in laboratories and in the field [55-62]. In the next section we will view olefinsulfonate structure-property relations [40] that have helped design optimum surfactants for enhanced oil recovery applications. 

B. Bubela. In situ biological production of surfactants for enhanced oil recovery. Australia Dep Resources Energy End of Grant Rep 151, March 1983. 

Jackson, A.C., 2006. Experimental Study of the Benefits of Sodium Carbonate on Surfactants for Enhanced Oil Recovery. M.S. thesis. University of Texas at Austin. 

Zhao ZK, Ba Y, Li ZS et al (2004) Dynamic interfacitil behavior of decyl methylnaphthalene sulfonate surfactants for enhanced oil recovery. Tenside Surf Det41(5) 225-229... 

Dodiflood Brands. [HoechstAG] Ether sulfonates, ether carboxylates anionic surfactants for enhanced oil recovery and miooemulsion flooding. 

Uses Surfactant for enhanced oil recovery and microemulsion flooding Properties Liq. 

Uses Surfactant for enhanced oil recovery operations where high temp, and pressure stability are necessary Properties Liq. 40% cone. 

The formation of ordered two- and three-dimensional microstructuies in dispersions and in liquid systems has an influence on a broad range of products and processes. For example, microcapsules, vesicles, and liposomes can be used for controlled drug dehvery, for the contaimnent of inks and adhesives, and for the isolation of toxic wastes. In addition, surfactants continue to be important for enhanced oil recovery, ore beneficiation, and lubrication. Ceramic processing and sol-gel techniques for the fabrication of amorphous or ordered materials with special properties involve a rich variety of colloidal phenomena, ranging from the production of monodispersed particles with controlled surface chemistry to the thermodynamics and dynamics of formation of aggregates and microciystallites. 

Optimizing the formulation of micellar surfactant solutions used for enhanced oil recovery consists of obtaining interfacial tensions as low as possible in multiphase systems, which can be achieved by mixing the injected solution with formation fluids. The solubilization of hydrocarbons by the micellar phases of such systems is linked directly to the interfacial efficiency of surfactants. Numerous research projects have shown that the amount of hydrocarbons solubilized by the surfactant is generally as great as the interfacial tension between the micellar phase and the hydrocarbons. The solubilization of crude oils depends strongly on their chemical composition [155]. 

W. A. Rendall, C. Ayasse, and J. Novosad. Surfactant-stabilized foams for enhanced oil recovery. Patent US 5074358, 1991. 

Large amounts of water and oil can be admixed in microemulsions which find wide application in household and pharmaceutical products and have potential for enhanced oil recovery (Mackay, 1981 Bellocq et al., 1984). Microemulsions have been reported to form in the absence of surfactant over a very limited range of concentration, but there is a question as to the nature of these dispersions (Barden and Holt, 1979). 

Mobility control, issues in, 18 626 Mobility control agents polyacrylamides as, 18 625 in polymer flooding, 18 622 Mobility control surfactants, in enhanced oil recovery, 18 625-628 Mobilizable vectors, for genetic manipulation, 12 471 Mobilization, of ascorbic acid, 25 771 Modacryhc fibers, 9 192 11 188, 189, 190 dyesite content of, 11 195 flame resistance of, 11 214 flammability of, 11 194 pigmented, 11 213 U.S. production of, 11 220t Mode conversion phenomenon, 17 422 Model agreements, 24 373-374 Model-based methods, for reliability, 26 1044... 

Figure 3.29 Illustrations of changes occurring in physical properties and other phenomena in the region of the optimal salinity for enhanced oil recovery using surfactant flooding. From Sharma [235]. Copyright 1991, Plenum Press.

Micro-foam, or colloidal gas aphrons have also been reportedly used for soil flushing in contaminated-site remediation [494—498], These also have been adapted from processes developed for enhanced oil recovery (see Section 11.2.2.2). A recent review of surfactant-enhanced soil remediation [530] lists various classes of biosurfactants, some of which have been used in enhanced oil recovery, and discusses their performance on removing different type of hydrocarbons, as well as the removal of metal contaminants such as copper and zinc. In the latter area, the application of heavy metal ion complexing surfactants to remediation of landfill and mine leachate, is showing promise [541]. 

In order to vary interfacial tension over more than four orders of magnitude, several fluid systems were chosen that ranged from high tension surfactant-free formulations to middle phase microemulsions that were at optimal conditions for enhanced oil recovery and had ultralow tensions with the excess brine and oil. Table I lists the specific components used along with their corresponding physical properties. In each case a red water-soluble food coloring dye was added before equilibration to enhance the contrast between phases during microscopy. 

Field Application. The micellar-polymer process for enhanced oil recovery has been used in many field trials. Petroleum sulfonates are the most commonly used surfactant 41, 42). Other surfactants have been used, such as ethoxylated alcohol sulfates 43) and nonionic surfactants mixed with petroleum sulfonates 44). 

The physicochemical aspects of micro- and macroemulsions have been discussed in relation to enhanced oil recovery processes. The interfacial parameters (e.g. interfacial tension, interfacial viscosity, interfacial charge, contact angle, etc.) responsible for enhanced oil recovery by chemical flooding are described. In oil/brine/surfactant/alcohol systems, a middle phase microemulsion in equilibrium with excess oil and brine forms in a narrow salinity range. The salinity at which equal volumes of brine and oil are solubilized in the middel phase microemulsion is termed as the optimal salinity. The optimal salinity of the system can be shifted to a desired value hy varying the concentration and structure of alcohol. 

During the past decade, it has been reported that many surfactant formulations for enhanced oil recovery generally form multiphase microemulsions (18-20). From these studies, it is evident... 

Solubllization. The effectiveness of surfactant formulations for enhanced oil recovery depends on the magnitude of solubilization. 

Phase Behavior. The surfactant formulations for enhanced oil recovery consist of surfactant, alcohol and brine with or without added oil. As the alcohol and surfactant are added to equal volumes of oil and brine, the surfactant partitioning between oil and brine phases depends on the relative solubilities of the surfactant in each phase. If most of the surfactant remains in the brine phase, the system becomes two phases, and the aqueous phase consists of micelles or oil-in-water microemulsions depending upon the amount of oil solubilized. If most of the surfactant remains in the oil phase, a two-phase system is formed with reversed micelles or the water-in-oil microemulsion in equilibrium with an aqueous phase. 

The phase behavior of surfactant formulations for enhanced oil recovery is also affected by the oil solubilization capacity of the mixed micelles of surfactant and alcohol. For low-surfactant systems, the surfactant concentration in oil phase changes considerably near the phase inversion point. The experimental value of partition coefficient is near unity at the phase inversion point (28). The phase inversion also occurs at the partition coefficient near unity in the high-surfactant concentration systems (31). Similar results were also reported by previous investigators (43) for pure alkyl benzene sulfonate systems. 

Salinity Tolerance. As the petroleum reservoir salinity can be very high, the surfactant formulations should be designed for high salt tolerance. The widely used petroleum sulfonates for enhanced oil recovery exhibit relatively low salt tolerance in the range 2-2.5% NaCl concentration, and even smaller for the optimal salinity. The presence of divalent cations in the brine decreases the optimal salinity of surfactant formulations (44). 

Hirasaki, G.J., Miller, C.A., Pope, G.A., 2006. Surfactant based enhanced oil recovery and foam mobility control. 3 Annual Final Technical Report for DOE project (DE-FC26-03NT15406, July. 

From the above discussion, it should be apparent that for POE nonionics, there is a particular temperature where the hydrophilic and lipophilic characters of the surfactant balance each other and yow is at, or close to, its minimum value. It is usually defined operationally, for example, as the temperature where the surfactant phase solubilizes equal volumes of water and nonpolar material or the temperature at which an emulsion (Chapter 8) of the surfactant, water, and nonpolar material inverts. In the latter case, it is known as the phase-inversion temperature (PIT) (Chapter 8, Section IVB). Similarly, there is an electrolyte content at which the hydrophilic and lipophilic characters of ionic surfactants balance. The point at which equal volumes of water and nonpolar material are solubilized into the surfactant is known as the optimal salinity (Healy, 1974) and has been extensively investigated for enhanced oil recovery (Healy, 1977 Hedges, 1979 Nelson, 1980). The optimal salinity or PIT is at or close to the point where the parameter Vh/lcao (Chapter 3, Section II) equals 1 and lamellar normal and reverse micelles are readily interconvertable. 

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