METHOD OF DRILLING AND DEVELOPMENT OF OFFSHOOTS FROM HORIZONTAL WELL Russian patent published in 2019 - IPC E21B7/04 E21B43/27 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to drilling and development of offshoots of oil and gas wells. Prior to drilling the offshoots with the main horizontal open borehole at the well head from below up the assembly is assembled: measure while drilling, one weighted drill pipe, wedge-deflector. Assembly is lowered on the tubing string to the main horizontal open borehole. Wedge-deflector is located in interval of offshoot kickoff. During lowering the tubing string is equipped with three starting couplings: at depths of 500 m – diameter of 1.5 mm, 700 m – diameter of 2.0 mm, 900 m – with diameter of 2.5 mm. Orientation of wedge-diverter is performed. Then, assembly is assembled at well head from bottom to top: milling cutter, screw downhole motor (SDM), hydraulic emergency disconnector. Assembly is lowered to the tubing string on the flexible pipe (FP) string. 10 m before the cutter-bore cutter of the deflector wedge the SDM is started and with pumping of the process liquid through the FP string are included in the wedge-deflector layout into the offshoot kickoff interval. Offshoot is drilled with load on cutter-bit to 1.5 t to preset face. During the drilling of the offshoot, compression is performed in a circle by feeding nitrogen into the annular space through starting couplings into annular space with aerating the spent process fluid. After the offshoot face reaching stopping the drilling process and raising the arrangement on the CT from the tubing string. Into the tubing string lowering the FP column with a spherical nozzle at the end to the offshoot drilled face depth and performing the offshoot bottomhole zone acidic treatment by the hydrochloric acid solution injection into the FP column with the FP column simultaneous displacement up to the offshoot kickoff interval. Depending on the number of offshoots, the above process operations are repeated, wherein the treatment pressure of the bottomhole zone of the side wellbore can be different for each offshoot.

EFFECT: higher reliability of the method, eliminating the clamping of the assembly during drilling, excluding the breakage of the FP column, higher quality of acid treatment of the offshoots.

1 cl, 5 dwg