Chevron Research & Technology Company

Chevron Research and Technology Company, a Division of Chevron U.s.a.

Donald L Kuehne

Jeremy Cantor

David M Marquis

Rawls H Frazier, Jr

Willard J Sevigny

Willie Horn, Jr

A method for enhancing the recovery of petroleum from an oil bearing formation during injection of a non-condensible gas comprises the at least periodic injection of a foam forming composition or a preformed foam into the reservoir. The foam which is produced comprises a mixture of a non-condensible gas, water and a non-ionic surfactant. The non-ionic surfactants which can be employed in the present invention are those non-ionic surfactants which have a HLB value of about 14 to less than 20, preferably 15-18, and which provide a stable foam when the surfactant is mixed with brine and/or water and a non-condensible gas. The method is preferably employed within a light oil bearing carbonate formation.

Enhanced oil recovery technique employing nonionic surfactants

An enhanced oil recovery technique for recovering hydrocarbons from a reservoir during gas injection comprises the at least periodic injection of gas and a foam-forming composition into the reservoir. The foam-forming composition comprises water, an effective foam-forming amount of a C.sub.10-16 .alpha.-olefin sulfonate surfactant including C.sub.10 AOS and/or C.sub.12 AOS, and an effective amount of at least one solubilizing component to increase the brine tolerance of the composition. This solubilizing component is a mixture comprising ##STR1## where M is H, an alkali metal, alkaline earth metal, or ammonium, where R.sub.1 is a linear C.sub.6 -C.sub.16 alkyl group. The method further comprises contacting the hydrocarbons in the reservoir with the foam so as to assist in the recovery of hydrocarbons from the reservoir.

Enhanced oil recovery method employing a high temperature brine tolerant

A foam-forming composition comprising a mixture of at least one anionic surfactant and at least one cationic surfactant can effectively form a foam in a variety of formations including an oil-wet environment. In particular, this composition can be employed in a method which comprises at least periodically injecting a gas and this foam-forming composition into an oil-bearing formation to drive oil to a production well. In this composition, the ratio of the at least one anionic surfactant to the at least one cationic surfactant is selected so that the surfactants do not form substantial amounts of precipitate when mixed together. In certain environments, e.g., when the formation contains upwards of 20% total dissolved solids and/or a divalent metal ion concentration up to about 20,000 ppm, the composition can further contain at least one salt-tolerance additive, e.g., a nonionic surfactant.

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Hercules, CA, United States of America

Donald L Kuehne