FIELD: oil and gas extractive industry, namely, methods for drilling branching boreholes in horizontal wells.
SUBSTANCE: method includes drilling in accordance to planned profile up to borehole branching point, performing necessary geophysical research, reinforcing the well and drilling branching boreholes. To provide for alignment-less precise insertion of drilling bit with bottomhole motor or tubing string into correct branching boreholes for performing required technological operations in well, drilling of first branching shaft is started with warping plane setting angle of deflector within limits of 70°-80° to the right or left from well borehole warping plane, depending on azimuth warping of second borehole. After completion of drilling of first borehole in accordance to planned profile and performing geophysical research, drilling of second borehole is started at same depth as first borehole, at setting angle of deflector warping plane within limits of 95°-100° relatively to warping plane of well borehole, while setting angle should be opposite to that during drilling of same interval in first borehole. If in first borehole setting angle is oriented to the left, then in second one it is oriented to the right, and vice versa. For boreholes to differ from each other, length of one of drilled boreholes is made greater for 10-20 meters. After completion of drilling of second borehole, geophysical research is performed analogically to case of first borehole. To provide for alignment-less insertion of pipes column being lowered into one of warping boreholes length of lower section, equal to 6-8 meters is made in form of arc with curvature radius equal to well warping radius at given section. When curved assembly being lowered into the well reaches cutting point, a mark is set at pipe thimble, which is applied onto rotor and pipe column is lowered further without rotation into one of branching boreholes, number of borehole is determined on basis of bottomhole dimensions. After performing necessary technological operations, if it is required to lower pipes column into another branching borehole, shoe of pipe column assembly is raised up to branching point and mark on thimble is shifted for 180° from original position by turning pipes column, and then the pipe is lowered into another borehole.
EFFECT: guaranteed alignment-less insertion of drilling tool or tubing string into correct branching borehole of horizontal well during various technological operations.
4 dwg
