Recovery Of Viscous Oils From Stratified Reservoirs Using Polymer Solutions

This paper was prepared for the SPE-European Spring Meeting 1974 of the Society of Petroleum Engineers of AIME, held in Amsterdam, the Netherlands, May 29–30, 1974. 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 OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Netherland Section of the Society of Petroleum Engineers, P. O. Box 228, The Hague, the Netherlands. 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 An analysis of the effectiveness of solutions of a series of seven polymers in the recovery of oil (220 cp) is presented. The rheologic properties of these polymer solutions in viscometers and their behavior in porous media are examined. Displacement tests were carried out in a quadrant of a five-spot model, with unconsolidated sand, using slugs of polymer solutions of varying viscosities. The viscosity gradients were the same for each polymer studied. There were definite increases in the oil recovery from these tests as compared to that obtained by employing water alone as displacing fluid. These increases ranged from 20% to 85% for the polymers with the lowest and the highest polymers with the lowest and the highest molecular weights respectively. Introduction Proper mobility control between the displacing and displaced phases in flow through porous media is important in the success of porous media is important in the success of secondary and tertiary recovery processes. Such control can be achieved in the waterflooding of oil reservoirs, by the use of slugs of polymer solutions, which act as mobility buffers between the water and oil phases. The types of polymers recommended for performing this function are the partially performing this function are the partially hydrolyzed polyacrylamides and the polysaccharides. In the design of a polymer flood, the selection of the concentrations of the appropriate polymer slug, necessitates an, understanding polymer slug, necessitates an, understanding of the particular rheologic behavior of the polymer solutions within the system (oil-water-rock) polymer solutions within the system (oil-water-rock) to be flooded. This paper presents experimental tests, to determine the effectiveness of solutions of several polymers in the secondary recovery of oil (220 cp), from a stratified reservoir. It outlines a simple procedure for determining the concentration of the polymer banks, and examines the rheologic properties of a series of polymers studied. EXPERIMENTAL PROCEDURE RHEOLOGY OF POLYMER SOLUTIONS A list of the polymers used in the experiments is presented in Table I.