Flow Characteristics of Surfactant Solutions in Porous Media and Their Role in Permeability Modification

Abstract

Kalpakci, B., SPE, Standard Oil Co. (Ohio) Klaus, E.E., Pennsylvania State U. Pennsylvania State U. Duda, J.L., SPE, Pennsylvania State U. Pennsylvania State U. Nagarajan, R., Pennsylvania State U. Pennsylvania State U. DECEMBER 1981 Abstract This paper presents results of a study on flow properties of surfactant solutions in porous media, properties of surfactant solutions in porous media, using the Penn State porous media viscometer. The effects of permeability, shear rate, and surface characteristics of porous media on the flow of oil- and water-external microemulsions, as well as surfactant solutions with lamellar structures, are examined. Untreated Bradford and Berea sand- stones, oil- and water-wet treated sandstones, and filter papers are used as porous media. The study shows that the effective viscosity of the surfactant solution (as measured in porous media), on the basis of initial permeabilities, is greater than the bulk viscosity (as measured by conventional viscometers). This increase is small for Newtonian surfactant solutions but is quite substantial for non- Newtonian surfactant solutions. The difference between bulk and effective viscosities of Newtonian surfactant solutions is eliminated when the effective viscosity is determined on the basis of the final permeability of the porous medium to calibration permeability of the porous medium to calibration solution. This indicates that the permeability of the porous medium during now of these Newtonian porous medium during now of these Newtonian surfactant solutions is equal to that during flow of postcalibration solutions. In contrast, in the case of postcalibration solutions. In contrast, in the case of the non-Newtonian surfactant solution with lamellar structures, the effective viscosity based on the final permeability remains higher than the bulk viscosity permeability remains higher than the bulk viscosity of the solution. Plausible explanations for the lower permeability during surfactant flow compared with permeability during surfactant flow compared with the final permeability, in this case, are discussed. It is found that the flow of surfactant solutions causes a permanent decrease in the permeability of the porous. medium. Initial permeability is not restored even by thorough flushing of the porous medium with surfactant-free brine solution. Residual permeability reductions of 2 to 51% are observed. permeability reductions of 2 to 51% are observed. The residual permeability reduction increases with decreasing initial permeability. The residual permeability reduction is relatively insensitive to the type permeability reduction is relatively insensitive to the type of surfactant solution. However, it depends on surface characteristics of the porous medium and decreases in this order: untreatedfired is greater th an oil-wet treated. Introduction According to Gogarty, about 60% of the potential oil reserves are estimated to be amenable to chemical flooding with surfactant and polymers. In surfactant/polymer flooding, the interaction of various chemicals with each other and with reservoir fluids and rocks, the permeability, the porosity, and the operating conditions are critical factors in determining the effectiveness of the process. Many studies of surfactant systems have been carried out relating to phase behavior, interfacial tension, and retention or adsorption characteristics. But only a few studies have been conducted on flow characteristics in porous media of surfactant fluids prepared with petroleum sulfonates, hydrocarbons, prepared with petroleum sulfonates, hydrocarbons, water, and electrolytes. These latter studies have not examined fully the flow characteristics over a wide range of permeabilities and shear rates, the influence of the permeability of porous media on the residual permeability reduction, and the influence of surface permeability reduction, and the influence of surface characteristics of porous media. Considering that sufficient viscosity level is an essential factor in mobility control during surfactant flooding, the importance of the rheology of surfactant solution in porous media is quite obvious. Information on porous media is quite obvious. Information on injectivity, effective viscosity, and permeability modification during the flow of surfactant solutions is also essential. SPEJ P. 709

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Flow of wormlike micellar solutions around confined microfluidic cylinders

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