Partially Hydrolyzed Polyacrylamides with Superior Flooding and Injection Properties

Abstract

ABSTRACT Polymers have found widespread use for oil field applications. They play an especially important role in secondary and tertiary oil recovery processes as mobility control agents.1, 2 For a variety of reasons, not the least of which is cost effectiveness, synthetic polymers are favored over their "natural" counterparts - the polysaccharides. Of the multitude of synthetic polymers, partially hydrolyzed polyacrylamide (PHPA) is the most widely used in a spectrum of enhanced oil recovery processes. PHPA reduces the mobility of displacement water in porous media (reservoir rock) by a combination of increasing its viscosity and reducing the permeability to water in accordance with the equation For permeability reduction, a manifestation of polymer retention, to be a useful factor, its effect must be propagated uniformly throughout the reservoir. Unfortunately, the available PHPAs of commerce share a common shortcoming - face plugging. That is, permeability reduction is greater around the injector than at more remote distances in the reservoir. Face plugging dramatically reduces injectivity and consequently prolongs project life. In view of this property of the commercial products, a study was undertaken at our laboratory to develop a high performance PHPA that does not exhibit preferential permeability reduction in the near-wellbore region.