METHOD OF DRILLING HORIZONTAL WELLS WITH PILOT SHAFT Russian patent published in 2016 - IPC E21B7/04 

FIELD: oil and gas industry.

SUBSTANCE: method of drilling horizontal well with pilot shaft, comprises drilling of pilot borehole with a given zenith angle for drilling of productive formation, performing geophysical investigations, lowering production string, cementing space behind string, installation of deflector, drilling of horizontal section in productive formation, according to invention, before installation of wedge-diverter is 3 times working out and trip of well bore in range of pilot borehole for 2-3 hours with flushing on technical water at pressure of 5-7 MPa by rotor assembly at a rate of not more than 20 m/h, lifting rotor assembly with well makeup with natural water suspension to mouth, packed-hole assembly is lowered, not allowing plantations of more than 2 t from own weight, inside drill assembly is lowered on telemetry cable at a rate of not more than 12.5 m/min, with control of makeup with process water every 200-300 m, gamma-ray logging is performed in range of positioning wedge-deflector, based on gamma-ray logging data mounting wedge-deflector and packed-hole assembly, anchoring assembly, disconnecting of cutter from wedge, well is transferred for washing with solution with density of 1,150-1,250 g/cm³, assembly is rotated at 25-35 rpm, magnets are installed in channels of circulation system, openings are cut with flushing solution of density 1,150-1,250 g/cm³ shaping casing string at initial axial load 0-0.5 t and speed of not more than 60 rpm, after cutting 0.4-0.6 m column axial load is increased to 3.5-4.5 t at speed of 70-80 rpm, flow rate is set at 12-16 l/s, continued until expanding part of mill exits casing string, processing cutting interval, cleaning bottom by lowering magnet on drilling tool.

EFFECT: drilling of offshoot without sticking of drilling tool.

1 cl, 3 ex