Abstract: A drilling fluid system comprising a brine and a quantity of cationic copolymers comprising a ratio of acrylamide monomers to cationic derivatives of acrylamide monomers, wherein the quantity and the ratio are effective to maintain effective rheology and fluid loss control in said drilling fluid system at temperatures of at least about 250° C. for at least about 16 hours.

Abstract: A method for producing a precursor polymer dispersion for addition to a brine for use in drilling and completion operations comprising providing a precursor brine having a first salt content, and mixing a water-soluble polymer with the precursor brine at a sufficient concentration and under conditions sufficient to produce a precursor polymer dispersion effective at a sufficient concentration in a final brine having a second salt content to improve the rheology and/or fluid loss control properties of the final brine.

Abstract: A drilling fluid system comprising a brine and a quantity of cationic copolymers comprising a ratio of acrylamide monomers to cationic derivatives of acrylamide monomers, wherein the quantity and the ratio are effective to maintain effective rheology and fluid loss control in said drilling fluid system at temperatures of at least about 250° C. for at least about 16 hours.

Abstract: A drilling fluid system comprising a brine and a quantity of cationic copolymers comprising a ratio of acrylamide monomers to cationic derivatives of acrylamide monomers, wherein the quantity and the ratio are effective to maintain effective rheology and fluid loss control in said drilling fluid system at temperatures of at least about 250° C. for at least about 16 hours.

Abstract: The present invention provides a method of preparing a fluid for use in drilling and completion operations comprising mixing a fluid comprising a salt of an alkaline earth metal with a nonionic colloid-forming material in an amount and under conditions sufficient to convert a majority of said nonionic colloid-forming material into water insoluble hydrated colloidal complexes comprising hydrated ions of said alkaline earth metal complexed with said nonionic colloid-forming material, said complexes being effective to improve a property of said fluid selected from the group consisting of rheology, fluid loss control, and a combination thereof.

Abstract: An oil-based fluid system has been discovered using a distribution of salt particle sizes, an oil or water/oil emulsion, a suspending agent for suspending the salt particles in the oil and a filtration control agent. It is important that the salt particles be distributed across a wide size range to effectively prevent filtration or fluid loss into the formation. Since the filter cake particles do not invade the well bore, no high pressure spike occurs during the removal of the filter cake. This high pressure spike indicates damage to the formation and well bore surface, which damage typically reduces overall permeability of the formation. The rheological properties of the fluid allow it to be used in a number of applications where protection of the original permeable formation is desirable. The applications include, but are not limited to, drilling fracturing and controlling fluid losses during completion operations, such as gravel packing or well bore workovers.