Patent ID: 9145512
Filing Date: 2015-09-29
Classification: C09K,E21B

Abstract:
1. A dual-phase acid-based fracturing composition for use in matrix acidizing and acid-fracturing operations in oil and gas wells for the prevention of corrosion of well tubing and downhole equipment, the composition comprising; a strong acid present in a concentration between 20% and 28% by weight that is operable to be diluted with treatment water and to dissolve formation rock; a liquid hydrocarbon comprising 5 or more carbon atoms; an emulsifier selected from the group consisting of an amine-based surfactant, linear alkyl amines and alkyl ammoniums; a hydrocarbon-soluble corrosion inhibitor comprising methanol and present in a range of 0.01% to 3% by volume relative to the amount of hydrocarbon in the composition; and an acid-soluble corrosion inhibitor that does not have surfactant properties and present in an amount of up to 3% by volume relative to the amount of acid in the composition; where the emulsifier is present in concentrations in a range of from 0.05% to 1.5% by volume relative to the amount of liquid hydrocarbon in the composition; where the acid during acid-based oil well operations forms a spent acid upon dissolving formation rock, where the composition is operable to coat metal tubing and well equipment with the hydrocarbon-soluble corrosion inhibitor such that the metal tubing and well equipment is protected from the acid during an injection phase; and where the composition is operable to coat the metal tubing and well equipment with the acid-soluble corrosion inhibitor such that the metal tubing and well equipment is protected from the spent acid during a flowback phase.