CASING DRILLING METHOD WITH RETRIEVABLE BOTTOMHOLE ASSEMBLY (RBA) Russian patent published in 2023 - IPC E21B7/04 

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. The method of casing drilling with a retrievable bottomhole assembly (RBA) includes identification of unstable rock zones and drilling a wellbore on a drill string with telemetry and a downhole drilling motor (DDM) bit until the top of unstable rocks. Then the assembly with the telemetry system and the DDM bit is removed. The well is drilled to the design bottomhole on a drill string with a casing tail. The casing tail consists of standard casing pipes, equipped with an auto-hook hanger on top, connecting the casing tail to the drill string, transmitting axial load and torque for drilling. After that, the drill string is uncoupled from the casing tail by dropping the ball from the wellhead into the saddle with increasing pressure in the tail and shearing the pin. Drilling is carried out using an RBA consisting of a retractable bit, a DDM and a telemetry system installed at the bottom of the tail using a connection unit. After drilling to the design bottomhole and extraction of the RBA for cementing, a suspension device is lowered, equipped with an automatic hitch assembly. The hitch assembly includes a conical groove of the saddle and a bushing. The saddle is spring-supported down relative to the body of the automatic releaser with limited downward movement until it stops against the shear element. The bushing is installed outside the body of the auto-releaser and is spring-supported downwards with the ability to move down to the locking ring and cover the hole of the auto-releaser with installed balls with the possibility of engaging the drill string lowered for cementing behind the inner groove of the hanger by moving the bush up and pushing the balls into the inner groove of the conical hanger saddle groove when landing the body of the auto-releaser on the end face of the suspension device.

EFFECT: increased speed of drilling a well on a casing string, control and monitoring of the trajectory during drilling on a casing string and extraction of the RBA upon reaching the design bottomhole.

1 cl, 6 dwg