UNSTABLE ROCKS DRIVING METHOD DURING DRILLING OF OFFSHOOT WITH HORIZONTAL END Russian patent published in 2020 - IPC E21B7/04 E21B33/10 

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to drilling of oil and gas wells, namely to methods of prevention of destruction and collapse of well walls at drilling intervals with unstable rocks. Unsustainable rocks driving method during drilling of offshoot with horizontal end, including window cutting in production string, drilling of the offshoot, attachment of the offshoot of the string with the shoe installed on the lower end, drilling of the offshoot to the projecting face. Method includes preliminary determining zone of unstable rocks of formation, after window cutting in production string, drilling of side bar bit with diameter of 1.3–2.5 % less than diameter of cut window with opening of zone of unstable rocks of formation, lower-string column-fly is lowered to the working face on the drilling string, equipped with a mounting device from above, and from below with a drilled working shoe, hydraulic pressure in the drilling pipe string is increased, the landing device is detached and removed from the drill string, at that, the diameter of the winding-free column is 7–8 % less than the diameter of the drilled offshoot, the drilling of the offshoot from the flush-joint column-volost to the design face is performed with chisel by 1.5–3 % less than the inner diameter of the flats-without winding column.

EFFECT: providing stability of process of driving and development of unstable hard-to-reach rocks of formation with diameter of well passage channel, drilling of well to project face with maximum possible diameter, direct flushing of well for removal of sludge, higher reliability of method, reduced labor input and duration of method implementation.

1 cl, 2 dwg, 1 tbl