DRILLING MUD Russian patent published in 2004 - IPC

FIELD: drilling fluids. SUBSTANCE: invention relates to compositions of drilling muds used for washing of bored oil and gas wells and in civil construction, in particular in inclined and horizontal boring, construction of underground passages. Drilling mud is based on water-oil emulsion and includes, kg/cu. m: bentonite mud powder 30-75, soda ash 1-2.5, sodium hydroxide 0.2-0.7, low-viscosity carboxymethylcellulose 2.5-6.8, two multifunctional surfactants: A 3-9 and B 0.5-3, foam suppressor 0.1-0.25, and acrylamide-containing polymer 2.6-4.5. Drilling mud can further contain attapulgite mud powder in amount no higher than 25 kg/cu.m, 4 kg/cu.m viscosity carboxymethylcellulose. Low-viscosity carboxymethylcellulose (really Na salt) has Brookfield viscosity no lower than 50 mPa.s in the form of 2% solution at 25 C and degree of polymerization 500-550. High-viscosity carboxymethylcellulose (really Na salt) has, respectively, higher than 1000 mPa.s and 700-800. When reaming and calibration of hole longer than 600 m and more than 1200 mm in diameter is required, drilling mud contains additionally 0.5-1 kg/cu.m bactericide. EFFECT: improved performance characteristics and environmental compatibility. 7 cl, 6 tbl