Foam drive method
AssigneeDa Qing Petroleum Administration Bureau
InventorDemin Wang
Life of this patent
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Abstract
A foam drive method for enhancing oil recovery efficiently is initiated by injecting into a subterranean oil-bearing formation, an aqueous polymer solution as a preceding-slug. This is followed by 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. The aqueous solution of foaming composition comprises an alkali, a surfactant and a polymer. Thereafter, an aqueous polymer solution used as a protecting-slug is injected into the formation; followed by continuing water-flooding.
Claims16
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 10−3 mN/m order of magnitude;
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- (3) injecting an aqueous polymer solution used as protecting-slug, in an amount of 10-45% pore volume of the formation.
Dependencies are inferred from the claim text.