DRILLING MUD Russian patent published in 1995 - IPC

FIELD: to sink unstable clay, argillites, salts, as well as for abnormally high pressure in formations. SUBSTANCE: oil or lubricating addition are substituted by water (61.0 - 39 per cent by weight); electrolytes (KCl, CACl₂,, MgCl₂,, NaCl, NaOH, Ca(OH)₂, bichromate etc.), (6.0 - 2.2 per cent by weight); bentonite clay or askanglina (27.0 - 7.0 per cent by weight); agents to adjust viscosity, water yield (starch, nitroglycerin, pitch etc.) (4.9 - 0.8 per cent by weight), YaRM-1 oil bearing addition (1.0 - 0.5 per cent by weight); barite (0.1 - 46.0 per cent by weight). As YaRM-1 added, stickiness of clay crust decreased by a factor of 2.25 (0.533 and 0.237), rock deformation (argillites) in the mud decreased by a factor of 10.6 (2.75 and 0.26), wedging pressure decreased by a factor of 1.77 (0.62 and 0.35 MPa), viscosity decreased by a factor of 1.18 (120 and 85 s), static shift stress decreased by a factor of 2 (24 and 12 MPa), water yield decreased by 14 per cent (5 and 4.3). EFFECT: increased rock stability on walls of the well, decreased gland generation and catching resulted from decreased stickiness of clay crust, decreased value of deformation and wedging rock pressure when swelled in the mud, as well as decreased viscosity, static shift stress and water yield. 3 tbl