Enhanced oil recovery technique employing nonionic surfactants

摘要

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.