METHOD OF DRILLING WELL WITH COMPOSITE STRING Russian patent published in 2024 - IPC E21B7/20 E21B33/14 

FIELD: drilling of soil or rocks.

SUBSTANCE: invention relates to drilling of oil and gas wells, namely to methods of drilling intervals with trouble zones. Method for sealing a well with a composite string includes determining a problem zone, drilling to the roof of the problem zone on the drill string with telemetry and a bit with a screw downhole motor with an angle set and a subsequent wellbore stabilization zone, extraction of assembly with telemetry system and bit with screw downhole motor, drilling the well to the design bottomhole on the drill string by the rotary method with the lower part of the composite string consisting of standard casing pipes equipped from below with a bit with PDC cutters, a centraliser to maintain a stable direction during drilling and a valve with a stop ring, and from above is a suspension device connecting the lower part of the composite string to the drill string, transmitting the axial load and torque for drilling, including a suspended squeezing plug with a stop device from above for seating and fixing a small squeezing plug, used in cementing the lower part of the composite string after drilling to the design bottom and washing the well shaft, besides, it is equipped with automatic detachment allowing to detach the drill string from the lower part of the composite string by dropping the ball from the wellhead into the seat at pressure increase in the composite string and the pin shear. After drilling to the design bottom and washing the well shaft, the lower part of the composite string is cemented, the drill string is detached from the lower part of the composite string, the smooth nipple of the upper part of the composite string is lowered and fitted in the guide bushing of the suspension device. Sealing is provided by sealing elements in the inner part of the guide bushing and connection of the conical lower part of the smooth nipple with the inner conical part of the lower part of the composite string. Composite string has equal-bore inner diameter along the whole length, after which hydraulic pressure is used to pressurize composite string, by increasing pressure the holes are opened due to shear of screws of plugs of upper part of composite string. Upper part of the composite string is cemented through the open holes. In the process of cement grouting, the squeezing plug is seated in the bushing of the upper part of the composite string, after which the pin is cut and the holes are closed by increasing the pressure.

EFFECT: sealing of the casing string and equal bore inner diameter along the whole length are provided.

1 cl, 4 dwg