Status of Surfactant or Micellar Methods

Abstract

Enhanced recovery with surfactants is being pursued as a means of increasing the U.S. energy supply. Laboratory and field work is under way on both low- and high-concentration processes to optimize the method of injecting surfactant. Critical factors in economic projections of surfactant recovery processes are oil recovery, oil price, and tax load. Introduction Enhanced recovery methods are being actively pursued by industry and through government projects as a means of increasing the U.S. energy supply. An additional 59 billion bbl of oil from known reservoirs are estimated to be recoverable with existing techniques, including surfactant methods, thermal techniques, and CO2 flooding. Of the potential reserves, about 60 percent are estimated to be amenable to chemical flooding with surfactants. This paper considers chemical flooding that uses surfactants for oil recovery. Background information is presented showing the development of both low- and presented showing the development of both low- and high-concentration surfactant processes. Laboratory results are discussed briefly to illustrate the different aspects of chemical flooding and to indicate trends of research. Field testing over the past 13 years is considered from the standpoint of using project results to predict full-scale development economics. The main thrust of the paper deals with steps necessary to commercialize a surfactant flooding process. The important question of chemical supply is discussed. Economic examples are presented based on Marathon Oil Co.'s experience in presented based on Marathon Oil Co.'s experience in Illinois. The effects of crude oil price and loss of statutory depletion on profitability are presented. along with capital requirements for a 6,000-acre, 10-year development program. Results show that proper economic incentives, including such things as favorable tax measures and high crude prices, will be needed before surfactant flooding processes can be used to develop large volumes of tertiary reserves. Concept Development Surfactant use for oil recovery is not a recent development in petroleum technology. Water-soluble surfactants were described as an aid to improve oil recovery in patents filed in the late 1920s and early 1930s. These patents taught the use of such water-soluble surfactants as a polycyclic sulfonic body and wood sulfite liquor in concentrations of 25 to 1,000 ppm. Other water-soluble compounds have been suggested by Holbrook for surfactant flooding; these compounds include organic perfluoro compounds, fatty acid soaps, polyglycol ether, salts of fatty or sulfonic acids, and polyglycol ether, salts of fatty or sulfonic acids, and polyoxyalkylene compounds. Laboratory results were polyoxyalkylene compounds. Laboratory results were presented showing that these solutions reduced presented showing that these solutions reduced interfacial tension and enhanced oil recovery. Publications since then have stressed coupling different salts with surfactants to reduce the interfacial tension to a minimum value and to prevent the adsorption of surfactants within the reservoir. These techniques have given rise to the low-tension surfactant flooding processes. In low-tension floods, much of the reservoir pore volume is filled with surfactant solution of a relatively low concentration. For example, a 30-percent PV slug containing less than 2-percent surfactant might be used. In 1959, Holm and Bernard filed for a patent in which they proposed injecting 0.1- to 3-percent surfactant dissolved in low-viscosity hydrocarbon solvent. This procedure reduced surfactant adsorption in waterwet formations. JPT P. 93