Abstract: The present invention is a method to improve permeability of a formation in the vicinity of a production wellbore. An acid treatment composition is placed in the formation after a foaming composition is injected and a foam created from the foaming composition, thus forcing the acid treatment composition into less permeable strata. The foaming composition contains a sulfate surfactant as a foam stabilization agent. The sulfate hydrolyzes after a time period that is long enough to permit placement of the acid treatment composition. After the sulfate hydrolyzes, it becomes ineffective as a surfactant. Fluids produced from the formation after the acid treatment according to the present invention therefore do not contain significant concentrations of active surfactants, and therefore do not create foams or emulsions in surface separation equipment.

Abstract: Oil recovery method using polymer solutions in which highly permeable strata are made significantly less permeable while less permeable strata are not made significantly less permeable. This is accomplished by heating more permeable strata by injection of hot fluids, and then injection of a crosslinkable vinyl aromatic-conjugated diolefin polymer and a temperature activated crosslinking agent. A crosslinked gel is formed in the initially more permeable strata, permitting recovery of oil from the initially less permeable strata.

Abstract: A pipe coating process capable of coating a pipe string after installing it in a well comprises wetting the pipe string walls with a hydrocarbon liquid containing an initially soluble block copolymer of elastomeric and glassy blocks plus a crosslinking agent for solidifying the polymer, and heating the liquid to solidify the polymer.

Abstract: Oil based well treating fluids comprise liquid mixtures of aliphatic and aromatic hydrocarbons containing aromatic hydrocarbons, polymeric materials inclusive of at least one block copolymer and polymer crosslinking agents, with the kinds and amounts of those materials tailored to the properties of the wells and the well treatment designs.

Abstract: A productivity-impairing water-block is removed from a subterranean reservoir by injecting an aqueous alkaline solution containing both an alkali metal borohydride and an acid-yielding reactant which is relatively slowly reactive.