Patent ID: 6494263
Filing Date: 2002-12-17
Classification: C09K

Abstract:
A method of removing filter cake from the walls of a well bore penetrating a producing formation deposited therein by a drilling or servicing fluid comprised of water, a water soluble salt and a particulate solid bridging agent comprising the steps of:(a) utilizing as the particulate solid bridging agent in said drilling or servicing fluid a chemically bonded ceramic selected from the group consisting of magnesium oxychloride cement, magnesium oxysulfide cement, magnesium potassium phosphate hexahydrate, magnesium hydrogen phosphate trihydrate and magnesium ammonium phosphate hexahydrate which is dissolvable in an aqueous clean-up solution containing a mild organic acid, a hydrolyzable ester, an ammonium salt and one of a chelating agent and an ammonium salt and a chelating agent; and (b) contacting said filter cake with said clean-up solution for a period of time such that said bridging agent is dissolved thereby.