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

FIELD: construction.

SUBSTANCE: method includes opening the window in the casing string of the main wellbore and drilling a new additional shaft to the design depth using a pullout wedge-whipstock, lowering a shank with casing strings at the mouth of the side wellbore, then sealing the side wellbore, drilling the shank top. The wedge-whipstock with an anchor is pulled out before the shank is lowered, which is equipped with a longitudinally corrugated suspension in the window zone, or made in the form of a longitudinal-profile pipe. The shank is placed in the side wellbore by means of a guide shoe attached from below. Correcting the corrugated sections of the shank is carried out by excess pressure with the fixation and the subsequent expansion in the side wellbore. Drilling the upper part of the shank is carried out in three stages; at the first one, a guiding window is cut in the shank to create the communication with the main wellbore; at the second one, the flaring of the upper part of the shank is made up to pressing it against the main wellbore walls above the window; at the third one, the upper part of the shank located in the main wellbore is removed. A device for drilling the upper part of the shank for the method implementation includes a tool with cutting elements made sliding, lowered on a pipe string and made with the possibility of rotation during drilling. A drilling tool is placed at the bottom of the device. Between the drilling tool and the cutting tool, a rolling tool with rotating rollers displaced in diameter relative to the cutting elements is installed. The distance between the drilling tool and the rolling tool is not less than the window length in the longitudinal direction of the main wellbore.

EFFECT: reducing the time, labour and material costs for the construction of a side wellbore from a previously drilled and cased well.

4 cl, 5 dwg