Abstract: A fluid mixture containing a high molecular weight polysaccharide composition with improved viscosity stability at high downhole temperatures and pressures encountered in common oil field applications, including hydraulic fracturing stimulation, drilling, cementing, and coil-tubing. The composition includes a salicylic acid solution, which, being a free-radical scavenger, prevents free-radical reactions within the high molecular weight polysaccharide that would otherwise adversely affect viscosity. The composition may also include an ascorbic acid solution, which reduces at least a portion of the oxidized salicylic acid to restore its function as a free-radical scavenger to prevent additional free-radical reactions with the high molecular weight polysaccharide. An alcohol solvent may also be utilized to increase the solution loading of salicylic acid.

Abstract: In accordance with the present invention, the rheology of an aqueous fluid is modified by a method which comprises adding to said aqueous fluid an amount of a viscoelastic composition sufficient to form a viscoelastic fluid. The viscoelastic composition of the invention comprises a combination of i) at least one alkyl amido quaternary amine, and ii) at least one coadditive that comprises a C8-24 linear alkyl and/or alpha-olefin sulfate and/or sulphonate.

Abstract: The present invention generally relates to a polyamide emulsifier, to a drilling fluid composition that comprises said emulsifier and to a method of drilling a borehole into a subterranean formation utilizing the drilling fluid composition of the invention.

Abstract: A drilling fluid comprising a pyruvate-free xanthan, which may be an acetate-free pyruvate-free xanthan, and a high density calcium-based brine. Preferably the pyruvate-free xanthan is a genetically prepared pyruvate-free xanthan. A process for recovering crude oil from an oil-bearing subterranean formation by drilling the formation and using a drilling fluid comprising a pyruvate-free gum and a high density calcium-based brine.

Abstract: The invention, in one embodiment, relates to a fluid loss control additive or composition comprising a granular starch composition and fine particulate mica, in specified proportions. The invention further comprises a fracturing fluid containing a starch composition and mica, in a specified ratio. In yet a third embodiment, the invention comprises a method of fracturing a subterranean formation penetrated by a borehole, comprising injecting into the borehole and into contact with the formation, at a rate and pressure sufficient to fracture the formation, a fracturing fluid containing starch and mica, in specified ratios, and in an amount sufficient to provide fluid loss control.