Development of a Hydrophobically Modified Water-Soluble Polymer as a Selective Bullhead System for Water-Production Problems

Abstract

Abstract For many years, bullhead systems have received a great deal of attention from the oil and gas industry. Because of the completion techniques used in many wells, protecting the hydrocarbon interval effectively during a water control treatment is not always practical or cost-effective. Bullhead systems offer the option of a treatment without zonal isolation and are designed to decrease water production with little or no decrease in oil or gas production. This paper describes the laboratory development of a new polymer that shows promise as a bullhead system. The material falls into the class of hydrophobically modified water-soluble polymers; that is, a water-soluble polymer into which water-insoluble moieties have been introduced. The unique associative and adsorptive properties of this class of polymers are well documented, but they have not been commercially exploited to a great extent in oil field applications. These materials offer improvements over the hydrophilic polymers traditionally used for permeability modifications. For example, hydrophobic modification appears to improve cleanup of the polymer that penetrates an oil saturated core, resulting in less risk of damage to oil permeability. Hydrophobic modification, depending on the structural features, also increases reduction to water flow in comparison to the unmodified polymer. This paper includes a general description of hydrophobically modified polymers and their properties, as well as detailed descriptions of the development and laboratory testing of the new system.