Oil reservoir permeability control

摘要

The permeability of a subterranean oil-bearing formation is controlled by the injection of an aqueous solution of a block copolymer containing polar and non-polar segments, with the polar segments generally making up at least 50 percent, usually 60 to 99 percent, of the copolymer. The polar segments are derived from an alkylene oxide and the non-polar segments from styrene or an alkyl styrene either by itself or with a diene. The copolymers may be cross-linked with polyvalent metal ions such as chromium and are normally used in solution concentrations of 1000-10,000 ppm. Diene units in the non-polar segment may be hydrogenated to reduce residual unsaturation and solubilizing functional groups such as sulfonate or hydroxyl may be present to improve water solubility.