HYDROPHOBIC EMULSION DRILLING FLUID AND A METHOD FOR PREPARATION THEREOF Russian patent published in 2004 - IPC

FIELD: oil and gas production.

SUBSTANCE: invention relates to drilling fluids on mixed water-hydrocarbon base with hydrophobic properties. Drilling fluid according to invention contains 44.8-58.1% of aqueous polymer-clay fluid, 30.1-40.0% of diesel fuel or petroleum, and 11.0-21.3% of emulsifier-stabilizer, which is 20% aqueous solution of pitch-origin carbolignosulfonate composed of, wt %: low-grade lignosulfonates 15.0-17.0, tall pitch 58.0-61.0, caustic soda 5.0-6.0, carboxymethylcellulose with degree of polymerization 700 and degree of substitution 85 - 18.0-20.0, water - the balance. Aqueous polymer-clay fluid is characterized by density 1180-1200 kg/m³ and filtration 2.0-2.5 cm³/30min. In a method of preparing hydrophobic emulsion drilling fluid comprising uniformly adding water, clay, polymer, and emulsifier-stabilizer to diesel fuel or petroleum at vigorous stirring until required values of technological parameters are obtained, pitch-origin carbolignosulfonate solution and aqueous polymer-clay fluid are added simultaneously.

EFFECT: enabled preparation of stable transition-type emulsion characterized by minimum filtration under thermobaric conditions and rheological parameters and viscosity controllable within a wide temperature range.

3 cl, 5 tbl