Patent ID: 6439308
Filing Date: 2002-08-27
Classification: C09K

Abstract:
A foam drive process, which comprises the following steps:(1) injecting into a subterranean oil-bearing formation, an aqueous polymer solution as a preceding-slug, in an amount of 2-8% pore volume of the formation; (2) periodically injecting simultaneously or alternately a non-condensible gas and an aqueous solution of foaming composition to form a combined foam under ground or periodically injecting the combined foam formed beforehand by the gas and said aqueous solution above ground, said aqueous solution of foaming composition comprises an alkali, a surfactant and a polymer, and injection amount of the aqueous solution is 10-50% pore volume of the formation, said aqueous solution of the foaming composition is a super-low interfacial tension system, and the interfacial tension value between the foaming composition and displaced subterranean oil may reach to 10âˆ’3 mN/m order of magnitude; and (3) injecting an aqueous polymer solution used as protecting-slug, in an amount of 10-45% pore volume of the formation.