Abstract: A method for improving the injectivity of water injection wells in those formations with a low permeability to water as compared to the formation's absolute permeability by the removal of residual oil from the formation pore spaces in the near injection wellbore area through the injection of an aqueous fluid containing an effective amount of surface-active agent. The surface-active agent has the general formulaRO(C.sub.3 H.sub.6 O).sub.a (C.sub.2 H.sub.4 O).sub.b YXwhere:R is an alkyl group containing about 3 to about 20 carbon atoms or an alkyl phenol where the alkyl portion of the alkyl phenol contains from about 3 to about 20 carbon atoms or a mixture thereof;a has an average value of between 0 and about 10;b has an average value of between about 1 and about 10;Y is a sulfate or sulfonate group; andX is a cation, preferably monovalent.

Abstract: Over-based oil-soluble magnesium sulfonate compositions are formed by one-step carbonation of a reactant mixture containing magnesium hydroxide formed in situ.

Abstract: Treatment of oil-soluble viscous liquid propene or butene polymers having a number average molecular weight of about 250-500 with gaseous sulfur trioxide in falling-film or static reactors yields acidic sulfonation products comprising alkenyl sulfonic acids and polymer sultones. Two-stage neutralization of the sulfonation product with ammonia or sodium hydroxide reduces the sultone content and increases the sulfonate content in the neutralized product.