METHOD TO CONSTRUCT WELL OF SMALL DIAMETER IN COMPLEX ROCKS Russian patent published in 2013 - IPC E21B7/00 E21B43/10 

FIELD: mining.

SUBSTANCE: direction is drilled with a chisel with diameter of 393.7 mm for the depth of 30-50 m, cased with a string with diameter of 324 mm, and the casing string annulus is cemented. From the direction a well is drilled on a natural aqueous suspension for an intermediate collar pipe with a chisel with a diameter of 295.3 mm for the depth of 150-190 m, at the same time the zone of landslides and absorbing for 20-40 m lower. In the zone of landslide and absorbing sludge is washed from a bottomhole by drilling mud with density of 1.12-1.20 g/cm³. The drilled well is cased with a string with diameter of 245-273 mm, and the casing string annulus is cemented by filling of cement mortar at the bottom and on the top to filling of the zone of landslides and absorbing. From the intermediate collar pipe they drill a collar pipe with a chisel with a diameter of 215.9 mm for the depth of 260-350 m at the natural aqueous suspension, at the same time the second zone of landslides and absorbing is tunneled for 100-150 m below. In the zone of landslides and absorbing the sludge is washed from the bottomhole with drilling mud with density of 1.12-1.20 g/cm³, cased with a string of 178 mm in diameter, and the casing string annulus is cemented by pouring of the cement mortar at the bottom and top before pouring of the zone of landslides and absorbing. From the collar pipe they drill a well for an operating string with a chisel with diameter of 144-155.6 mm to design elevation, the operating string with a diameter of 114 mm is lowered, the casing string annulus is cemented. Ending of the well may be arranged with a horizontal shaft.

EFFECT: method improvement.

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