PROCESS FLUID FOR BORING, COMPLETION AND MAJOR REPAIRS OF OIL AND GAS WELLS UNDER ABNORMALLY HIGH FORMATION PRESSURE AND ELEVATED TEMPERATURE CONDITIONS Russian patent published in 2003 - IPC

FIELD: oil and gas production. SUBSTANCE: invention aims at increasing thermal stability of weighted process fluids to 200 C and simultaneously reducing negative physicochemical effects on productive stratum due to prevention of formation of insoluble sediments and emulsions. This aim is achieved by using water- based process fluid containing 0/1-7.0% polysaccharide reagent or mixture of polysaccharide reagents, 45.0-83.0% weighting agent, in particular formic acid alkali metal salts. Fluid can also contain 0.1-2.0% complex cross-linking agent selected from mineral salts of mono-, di-, and trivalent metals and alkaline pH regulator, and further acid- soluble weighting agent, for example carbonate flour and marble aggregate. EFFECT: increased heat resistance. 3 cl, 2 tbl, 2 ex