METHOD FOR CONSTRUCTION OF ADDITIONAL WELL BORE OF MULTI-LATERAL WELL AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2017 - IPC E21B7/08 E21B43/10 E21B33/10 

FIELD: oil and gas industry.

SUBSTANCE: method for construction of additional well bore of the multi-lateral well includes preliminary expansion of inner diameter of the casing string of primary well bore in window location zone and above, lowering and installing a removable wedge-deflecting tool, opening the window and drilling a new additional well bore to the designed depth, removal of the wedge-deflecting tool and lowering a shank equipped with longitudinally corrugated suspension or made of longitudinally profiled tube with an enlarged perimeter in expansion zone of the primary casing string inner diameter. The shank is directed and placed in additional well bore by means of a guide shoe attached below, straightening the corrugated sections of the shank is performed by excessive pressure with fixation by flaring in additional well bore. The upper part of the shank is processed in two stages, at the first stage the guide window is cut out in the shank to create communication with the primary well bore, at the second stage- the upper part of the shank is expanded before pressing thereof flush to the expansion of the primary well bore walls. The device for processing of the upper part of shank includes a cutting tool lowered on a pipe string and configured for rotation, and placed below for cutting the window for communication with the well bore. Above the cutting tool, there is a rolling tool with rolling rotary extensible rollers. The distance between the cutting and rolling tools is not less than length of the window in longitudinal direction of primary well bore.

EFFECT: simplified construction of multi-lateral well from previously drilled and cased wells, reduction of time, labour and material costs.

2 cl, 10 dwg