The Behavior of Polymers in Porous Media

Abstract

This paper was prepared for the Improved Oil Recovery Symposium of the Society of Petroleum Engineers of AIME, to be held in Tulsa, Okla., April 22–24, 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 paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested 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 discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract A partially hydrolyzed polyacrylamide and a biopolysaccharide are being investigated for use as mobility control agents in water flooding and in chemical flooding. Both polymers have functioned satisfactorily in some of our laboratory experiments and unsatisfactorily in others. The polyacrylamide has given adequate mobility control in moderate permeability rocks when it is injected under conditions which minimize shear degradation. In bead pack flow experiments, we found that degradation occurs at shear rates of about 1000 sec-1. The polysaccharide solution was only slightly degraded by exposure to shear rates of about 30,000 sec-1. These observations, if applicable to field injection situations, limit injection rates severely in wells with restricted entry completions. Mobility control with the polyacrylamide results from an increase in fluid viscosity and a reduction in permeability. The viscosity effect can be measured in permeability. The viscosity effect can be measured in laboratory viscometers but the permeability reduction must be determined from a series of core floods. As the polysaccharide functions only to increase fluid viscosity, estimation of mobility control for a given system is simplified. Viscosity of fluids containing either polymer can be reduced by shear degradation and, in the case of the polyacrylamide permeability reduction for a given fluid-core system can be severely lowered by shear degradation of the polymer. The polysaccharide solutions compared with polyacrylamide solutions are less sensitive to shear polyacrylamide solutions are less sensitive to shear degradation, less sensitive to viscosity reduction by increasing salt concentration and are amenable to the use of simplified mobility design procedures.