WELL CONSTRUCTION METHOD IN COMPLEX GEOLOGICAL CONDITIONS Russian patent published in 2019 - IPC E21B7/00 E21B33/138 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used in construction of inclined well with zenith angle of more than 25° on sections of the shaft with cavitation and absorption of rocks located below the Vereiskian horizon. In the proposed method, prior to drilling, at the drilling section, determining the formation and absorption zones located below the Vereiskian horizon, then drilling and lowering the direction, the conductor, opening the slanting zone of the Vereiskian horizon, deepening the working face below the shedding zone by 10–15 meters, flushing the wellbore to form caverns in the cavity formation zone, process exposure for falling of enclosing clay rocks from caverns, installation of cement bridge, process maintenance for expectation of hardening of cement for 4–6 hours, drilling of cement bridge. Then, drilling on clayey solution with density close to formation rock fluid density is continued until the absorption zone is opened, the absorption zone is insulated by the cement bridge installation, then cement bridge is installed on section of well shaft with overlapping of cavity formation zone with height of not more than 80 m, process curing is carried out for solidification of cement bridge during 4–6 hours with its further drilling and drilling is continued to design depth.

EFFECT: use of the method enables drilling of an inclined well with a zenith angle of more than 25° in conditions of caver formation and absorption of rocks located below the Vereiskian horizon, without complications.

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