FIELD: soil or rock drilling.
SUBSTANCE: invention relates to technical means for drilling side holes from the horizontal part of an open borehole, in particular to drilling devices using long-length flexible pipes (coiled tubing). Bottom hole assembly (BHA) for drilling offshoots from the horizontal part of the open borehole includes a string of long flexible pipes (LFP), a bit, a downhole motor and a centraliser. Column of long flexible pipes, in series from bottom to top, is equipped with a bit, an oscillation-turbulence promoter with screw slots made on its outer surface, screw downhole motor and hydraulic emergency disconnector, made in the form of a hollow housing, which is equipped with a ball inside a landing seat for a lengthy flexible pipes discharged from the wellhead into the string. Lower end of the string of long flexible pipes is connected to the housing of the hydraulic emergency disconnector by shear pins. Centraliser is equipped with overflow channels. On the outside, hydraulic emergency disconnector is equipped with external cylindrical recess for gripping by external spear.
EFFECT: arrangement reduces probability of BHA sticking, in case of BHA clamping in the side borehole disconnect the LFP column from BHA, and then to remove BHA from side barrel, to increase drilling bit speed during drilling of offshoot, which allows to reduce time of works and reduce costs, reduce metal consumption, direct the trajectory of the offshoot for effective opening of the productive formation.
3 cl, 6 dwg
