METHOD FOR DRILLING A SIDETRACK OF A WELL WITH UNSTABLE ROCKS Russian patent published in 2023 - IPC E21B7/04 E21B33/10 

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the field of drilling oil and gas wells, and in particular to methods for preventing the destruction and collapse of the walls of the well when drilling intervals with unstable rocks. A zone of unstable rocks is preliminarily determined according to adjacent wells and from well logging data. A port is cut out in the production string. Drilling of the lateral wellbore is carried out on a drill string with telemetry and a drill bit with a screw downhole motor with a slide down zone and a subsequent wellbore stabilization zone up to the top of unstable rocks. The assembly with the telesystem and a downhole motor is removed, and the well is drilled to the design bottomhole using a rotary method with a drill string and a casing liner. The casing liner consists of standard casing pipes equipped with a PDC bit, centralizer and valve from below. The casing tail consists of an auto-hook hanger on top, connecting the casing tail to the drill string, transmitting axial load and torque for drilling. To achieve the target bottomhole during drilling, the trajectory is controlled by a centralizer with a variable circumscribed diameter, which increases the circumscribed diameter with an increase in the pressure of flushing fluid pumping due to the exit of the blades, advanced by the pistons, the under-piston cavity of which is connected by a hole with the central channel. To control the trajectory when drilling above the check valve, the drilling liner is equipped with a non-magnetic branch pipe with a retractable inclinometer module. Thanks to the centralizer with a variable circumferential diameter and the inclinometry module, it is possible to control the trajectory while drilling a well section with a casing liner. After removing the inclinometry module while pumping the required volume of cement, the ball is dropped and placed in the central hole of the check valve to increase the pressure of the flushing fluid in order to open holes for washing out excess cement after cementing. After that, the drill string is uncoupled from the casing liner by dropping the ball from the wellhead into the saddle with increasing pressure in the liner and shearing the pin. The bit is provided with a plugged cementing hole, the plug of which opens when the bit holes become clogged during cementing.

EFFECT: control and monitoring of the trajectory during drilling of a well section with a casing liner, elimination of emergency situations due to clogging of the drilling holes of the bit during cementing.

1 cl, 5 dwg