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

The mobility buffer commonly employed in micellar solution flooding is an aqueous solution of a partially hydrolyzed polyacrylamide polymer. By virtue of the polymer absorption polymer. By virtue of the polymer absorption and entrapment in the porous medium, a certain fraction of the pore volume may be inaccessible to the original polymer solution. This would imply that the mobility control at the rear of the slug is not totally effective.

In view of the above effects, this investigation was devoted to a study of alternate mobility buffers and in the micellar solution flooding process. Specifically, glycerine and sucrose were employed as buffers, for a particular slug (supplied by the Marathon Oil Company). particular slug (supplied by the Marathon Oil Company). Attempts were made to use starch buffers as well. Effects of the buffer size and type on oil recovery were compared with those for polymer buffers. Such comparisons were repeated for different micellar solution slug sizes. All buffers were designed to provide the same mobility control. Runs were carried out at a constant rate, in linear sandstone cores.

It was found that, on the whole, the buffer investigated can be graded as follows: sucrose buffers are most effective in increasing oil recovery, with a concommitant increase in the oil production period, the injection pressures being moderate; polymer buffers are less effective, and injection pressures are high; glycerine buffers are similar in behavior to polymer buffers, but are frequently less polymer buffers, but are frequently less effective, with lower injection pressures, however. No definitive results were obtained for starch buffers; the injection pressures being prohibitively high. The relative oil recovery effectiveness of the buffers tested was explained in terms of the buffer - slug miscibility. It is felt that studies on other materials may lead to a better alternative to polymer solutions, with regard to both oil recovery and injection pressure.

Introduction

Micellar solution flooding is an important tertiary oil recovery process which employs a combination of a suitable hydrocarbon, water, a surfactant, and possibly other additives, as the "slug", which is miscible with both the crude oil and water. Although such a microemulsion is not a true solution, it provides a "bridge" that enables the water and oil to act as though they were miscible. The mobility of a micellar solution is adjusted through compositional changes to realize a high oil recovery.

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