Abstract: Fluids, such as completion fluids, containing at least one alkali metal tungstate and optionally at least one chelating agent are described. Methods of removing a filter cake from a well bore surface, which may include one or more alkaline earth metal sulfates, is also described, wherein the method includes contacting the filter cake with the completion fluid of the present invention. A drilling fluid or mud is also described wherein the drilling fluid contains at least one alkali metal tungstate. The drilling fluid preferably further contains at least one emulsifier or surfactant and at least one hydrocarbon-based fluid. The various fluids of the present invention can contain other conventional ingredients and optionally at least one alkali metal formate. The present invention permits the fluids to be essentially solids free due to the use of the alkali metal tungstate.

Abstract: An aqueous-based composition containing cesium formate and at least one chelating agent is described. Methods of removing scaling deposits, which may include alkaline earth metal sulfates, present on surfaces, including porous media, such as alkaline earth metal sulfate buildup in a well bore, is also described, wherein the method includes contacting the alkaline earth metal sulfate with the compositions of the present invention to remove the scaling deposits. A completion fluid containing at least one alkali metal formate, at least one acid and/or at least one chelating agent, and optionally at least one surfactant or mutual solvent is also described. Methods of removing a filter cake from a well bore surface, which may include weighting agents such as calcium carbonate, is also described, wherein the method includes contacting the filter cake with the completion fluid of the present invention.

Abstract: Fluids, such as completion fluids, containing at least one alkali metal tungstate and optionally at least one chelating agent are described. Methods of removing a filter cake from a well bore surface, which may include one or more alkaline earth metal sulfates, is also described, wherein the method includes contacting the filter cake with the completion fluid of the present invention. A drilling fluid or mud is also described wherein the drilling fluid contains at least one alkali metal tungstate. The drilling fluid preferably further contains at least one emulsifier or surfactant and at least one hydrocarbon-based fluid. The various fluids of the present invention can contain other conventional ingredients and optionally at least one alkali metal formate. The present invention permits the fluids to be essentially solids free due to the use of the alkali metal tungstate.

Abstract: An aqueous-based composition containing cesium formate and at least one chelating agent is described. Methods of removing scaling deposits, which may include alkaline earth metal sulfates, present on surfaces, including porous media, such as alkaline earth metal sulfate buildup in a well bore, is also described, wherein the method includes contacting the alkaline earth metal sulfate with the compositions of the present invention to remove the scaling deposits. A completion fluid containing at least one alkali metal formate, at least one acid and/or at least one chelating agent, and optionally at least one surfactant or mutual solvent is also described. Methods of removing a filter cake from a well bore surface, which may include weighting agents such as calcium carbonate, is also described, wherein the method includes contacting the filter cake with the completion fluid of the present invention.