Method for enhancing the recovery of petroleum from an oil-bearing formation using a mixture including anionic and cationic surfactants

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