METHOD OF CONSTRUCTING ADDITIONAL WELLBORE AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2017 - IPC E21B7/08 E21B33/10 E21B43/10 

FIELD: mining.

SUBSTANCE: method involves opening the window in the casing of the primary wellbore and drilling a new additional wellbore to the design depth using a whipstock, lowering the shank with the casing at the mouth of the additional wellbore, then sealing the additional wellbore, drilling the upper part of the shank. The whipstock with an anchor is removed before the shank is lowered, which is equipped in the window region with a longitudinally corrugated suspension or made in the form of a longitudinal profile pipe. On the surface of the longitudinal profile pipe, transverse annular grooves are made before the profiling, and longitudinal stiffeners are fixed on the surface. The shank is placed in the additional wellbore with a guide shoe attached from below. Straightening of the corrugated shank portions is carried out by excess pressure with fixation by expanding in the additional wellbore. The drilling of the upper part of the shank is carried out in three stages; at the first stage, the guiding window is cut out in the shank to create a connection with the main wellbore; on the second stage - flaring of the upper part of the shank, before pressing it against the walls of the primary wellbore above the window; on the third stage - removal of the upper part of the shank in the primary wellbore. The device for drilling the upper part of the shank for the implementation of the method includes a tool with the cutting elements that is descended on the pipe string and configured to rotate while drilling. A drilling tool is placed at the bottom of the device. Between the drilling and the cutting tools, a rolling tool with rotating retractable rollers is installed, which are offset in diameter relative to the cutting elements. The distance between the drilling and the rolling tools is not less than the length of the window in the longitudinal direction of the primary wellbore. The cutting elements of the cutting tool are made sliding.

EFFECT: reliable mechanical connection between the casing strings of the multi-borehole shafts, preservation of the flow section of the primary wellbore, reduction of time, labour and material costs for the construction of an additional wellbore from previously drilled and cased wells.

3 cl, 10 dwg