Patent ID: 6637517
Filing Date: 2003-10-28
Classification: C09K,E21B,Y10S

Abstract:
A method of acidizing a formation having a hydrocarbon zone and a water-baring zone, the method comprising:(a) selectively blocking the pore structure in the water-bearing zone at the formation face to selectively retard migration of acid into the water-bearing zone and allow migration into the hydrocarbon zone; and (b) injecting acid into the formation, wherein the acid is diverted from the water-bearing zone to the hydrocarbon zone as a result of selectively blocking the pore structure in the water-bearing zone at the formation face, wherein the step for selectively blocking forms a plug of viscous fluid in the pore structure of the water-bearing zone at the formation face, and wherein the viscous fluid has at least (i) a viscosifying surfactant capable of forming micelle in an aqueous environment; (ii) a water-soluble salt to effect formation stability, and (iii) an aqueous carrier fluid in which the viscosifying surfactant forms the viscosifying micelles.