Method for foam emplacement in gas flooding for enhanced oil recovery

摘要

A method for improving the sweep efficiency of gas or steam flooding operations by reducing the permeability of relatively high permeability thief zones of an oil bearing subterranean reservoir having heterogeneous and/or fracture permeability and that is penetrated by at least one well is disclosed. A controlled quantity of a surfactant is injected into a high-permeability zone of a reservoir. Controlled quantities of a gas and a subsequent surfactant are then injected, simultaneously or alternatively into the same well, so that a controlled amount of foam having a controlled quality is generated in the high permeability zone, thereby reducing permeability. Following foam emplacement, a chase gas may be injected, and the steps of injecting surfactant and gas may be repeated as necessary to lower the gas-oil ration of non-problem offset producing wells to a preset limit.