Structure and Process Optimization for the Use of a Polymeric Relative-Permeability Modifier in Conformance Control

Abstract

Summary For many years, relative-permeability modifiers (RPMs) have received a great deal of attention from the oil- and gas-production industry. Because of the completion techniques used in many wells, it is not always practical or cost-effective to protect the hydrocarbon interval properly during a water-shutoff treatment. RPMs offer the option of bullheading a treatment without zonal isolation, which is designed to decrease water production with little or no decrease in oil or gas production. This paper describes the laboratory development and optimization of a polymeric RPM. The resulting material can be best described as a brush polymer consisting of a polymeric backbone grafted with methoxypolyethylene glycol (MPEG). Various phases of the development will be discussed, such as the optimization of the molecular weight of the backbone polymer and the concentration of grafted MPEG. Details of laboratory evaluations will also be provided, including a discussion of the use of multipressure-tap flow cells for permeability-reduction tests, the effect of polymer concentration, and the effect of saturations. These test results show that the RPM polymer should be placed with a systematic approach consisting of proper preflushes and postflushes for optimum results.