METHOD FOR DRILLING OF LATERAL TRUNK WITH UNSTABLE ROCKS Russian patent published in 2022 - IPC E21B7/04 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the field of drilling of oil and gas wells, namely to methods for prevention of destruction and collapse of well walls, when drilling intervals with unstable rocks. A method for drilling of a lateral trunk with unstable rocks includes determination of unstable rock zones, cutting of a window in a production string, drilling of the lateral trunk to a computed backwall, attachment of the lateral trunk with a pipe string, increase in hydraulic pressure in the drill pipe string, uncoupling, and extraction of a boat landing. From the window, drilling is carried out on the drill string with telemetry and a chisel with a screw downhole drilling motor with an angle set and a subsequent zone of stabilization of a wellbore to a top of unstable rocks. Then, the arrangement with the telemetry system and the chisel with the screw downhole drilling motor is extracted, and the well is drilled to the computed backwall by a rotor method, on the drill string with a well liner consisting of standard casing joints. Casing joints are equipped below with a chisel with PDC cutters, a centerer for preservation of a stable direction in drilling, and a valve with a stop ring, and with a suspension device from above. The well liner is connected to the drill string with the suspension device transmitting an axial load and torque for drilling. Displacement plugs of the suspension device are used in cementing of the liner after drilling to the computed backwall and washing of the wellbore. The drill string is uncoupled from the well liner due to discharge of a ball from a head to an upper bend, while increasing pressure in the liner and cutting a pin, while a length of the well liner is equal to the sum of a length of the lateral trunk of the well to the backwall and a section L of the liner for sealing in the production string. Then, according to data of geophysical studies, the liner is perforated at an interval of a productive formation, and the well is put into operation.

EFFECT: drilling of unstable impassable rocks of a formation to a computed backwall without lifting of an arrangement, increase in the reliability of implementation of a method due to directional drilling and subsequent cementing of a liner, reduction in labor intensity and duration of implementation of the method, reduction in material costs for implementation of the method due to elimination of intermediate strings and reduction in lowering-lifting operations.

1 cl, 2 dwg