Secondary Recovery Stimulation Techniques and Chemicals

The widespread use of waterflooding has presented many new problems to the petroleum industry. Most of these problems are directly related to the physical process of pumping great volumes of water at high pressures into water injection wells. Until the past few years, methods of increasing or maintaining injectivity were limited to the conventional techniques of acidizing or fracturing. Within the past three or four years, however, stimulation techniques have been developed primarily for problems related directly to water injection wells. The first involves the use of sodium hypochlorite solutions followed by acid solutions to remove permeability damage caused by bacterial activity. Such activity can result in creation of large amounts of organic material and tremendous loss in permeability. The second new stimulation technique is the use of micellar dispersions. These fluids remove most of the residual oil saturation near the wellbore and greatly increase the formation permeability to water. Both new injection well stimulation methods have been widely used and have been proven highly successful. The purpose of this paper is to describe these new techniques and point out how and when they should be used. Treatment design is also discussed; case histories are presented to show the success of these types of treatments as well as to point out some of the conditions that can contribute to their unsuccessful use.