WELL CONSTRUCTION METHOD Russian patent published in 2015 - IPC E21B7/00 E21B21/00 

FIELD: oil and gas industry.

SUBSTANCE: method includes drilling by an assembly with a hydraulic downhole motor, periodical reciprocating of a drilling string in the complicated zone with simultaneous rotating. Drilling is performed by a bit having a diameter of 220.7 mm, a sloughing rock horizon is drilled and the drilling fluid is used with a density of 1.3-1.4 g/cm³, viscosity of 50-90 CP, load to the bit is maintained within limits of 10-15 t, the drilling fluid is injected with a rate of 32-45 l/s, the productive formation is entered to a depth of 1.0-1.5 m with a zenith angle of 75-85 degrees. The sting below assembly is lifted above the sloughing rock horizon, the process is withheld within 1-2 hours, and the assembly is lifted from the well, logging survey is performed and the same assembly is run in. At running in the setting intervals are worked out, the assembly is lifted out of the well, the production string is run in to the bottomhole with a lower section of casing pipes, a docking device and an upper section of drill pipes, the borehole annulus of the lower section is cemented, the upper section is disconnected from the docking unit, the upper section of the drill pipes is lifted and the casing string with a diameter of 177.8 mm is run with the length from the docking device up to the wellhead, the strings are lined up and the borehole annulus is cemented. A packed-hole assembly with a bit of a diameter of 155.5 mm is run in inside the production string, the interval of the sections line-up is worked out and drilling of the productive formation is continued.

EFFECT: excluded sticking of drilling tools when passing the well through complicated zones.