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American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., April 7–9, 1975. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Up-to-date results of large and small micellar solution field tests illustrate the successful application of the process. Advances in techniques for laboratory scale test design and for manufacture of injected fluids provide the basis for economic application of the process. Introduction Micellar solution flooding (the Maraflood TM oil recovery process) is a viable enhanced oil recovery technique. The process may be used either for secondary or tertiary recovery. Although significantly more expensive and risky than waterflooding, the process is economical in a large category of petroleum reservoirs with current crude price projections. This paper briefly describes the micellar flooding process, gives results of three field tests, describes a core flooding technique for process evaluation, presents a new process for direct sulfonation of presents a new process for direct sulfonation of crude oil and manufacture of micellar solution in the field, and summarizes process economics. The paper also comments on future development and application of the process. The micellar solution flooding process requires injecting a sequence of fluids into a producing petroleum reservoir. Initially, a producing petroleum reservoir. Initially, a slug of micellar solution (commonly referred to as micellar slug or simply as slug) is injected. While effective, the micellar slug displaces essentially 100% of the oil it contacts. Since this material is expensive, it is displaced by a more economical fluid, the mobility buffer. The mobility buffer must be capable of efficiently displacing the slug through the reservoir if slug effectiveness is to be maintained. Thus, the buffer mobility should be lower than slug mobility. (Mobility is defined as effective permeability to flowing fluid divided by apparent permeability to flowing fluid divided by apparent fluid viscosity.) If the mobility-buffer mobility is too high, it may finger through the slug, resulting in serious-inefficiencies in the micellar flooding process. The mobility buffer may be a viscous emulsion, or more commonly, a polymer-water solution. The buffer is generally displaced by water, in spite of unfavorable mobility control at the water-mobility buffer interface. Water is used because of availability and low cost. It is essential that the mobility-buffer bank be large enough to prevent the water from fingering through the mobility prevent the water from fingering through the mobility buffer into the micellar slug before completion of the flooding process. Typical fluid volumes for tertiary recovery are five to ten percent pore volume micellar slug, approximately one pore volume of mobility buffer, and approximately one-half pore volume of water. Laboratory development and testing and field testing of the micellar flooding process have been under way for many years, although interest has increased since about 1970. The process has been proven to be technically successful in a wide variety of field tests. Marathon Oil Company started field testing the micellar flooding process with the Dedrick pilot flood in November, 1962.