METHOD FOR CONSTRUCTION OF DOWNHOLE SPLITTER AND WHIPSTOCK FOR ITS IMPLEMENTATION Russian patent published in 2014 - IPC E21B7/08 E21B29/06 

FIELD: oil and gas industry.

SUBSTANCE: method lies in installation of fixing unit with a whipstock for one deflective surface in the main hole constructed up to the design depth. The fixing unit is made in the form of hydromechanical anchor with mounting seat, at that the anchor is fixed below the sidetracking space. Before sidetracking the casing pipe is penetrated by window cutting and after offshoot construction the whipstock is retrieved from the well disconnecting it from the fixing unit; auxiliary longer whipstock is run in till it interacts with the mounting seat of the anchor fixing it from rotation; before sidetracking of additional offshoot the casing pipe is penetrated by additional window with subsequent retrieval of auxiliary whipstock after construction of the second offshoot. The device for method implementation includes a whipstock run in at the pipe string and equipped with one deflective surface and connected from below by breakable elements through the crossover shoe with the fixing unit made in the form of hydromechanical anchor equipped with longwise corrugated pipe blinded from below with the shoe and a hydraulic centring skid located below the crossover shoe. At that centring skid is manufactured as a body with a gallery communicating with longwise corrugated pipe, pipe string and pushers located evenly along the perimeter and height of the body limits radial movement outside until interaction with the casing walls at excess pressure in the gallery; at the top the body is equipped with a groove for matching intrusions of the crossover shoes of the whipstock and auxiliary whipstock in order to exclude rotation and ensure their setting in preset direction.

EFFECT: group of inventions allows drilling of two opposing additional boreholes from the same level of the existing well, engaging of the main borehole into operation and reducing material costs for construction of the downhole splitter.

3 cl, 4 dwg