METHOD FOR RECOVERY OF PERMEABILITY FOR OPEN HORIZONTAL BOREHOLE Russian patent published in 2015 - IPC E21B21/00 

FIELD: oil and gas industry.

SUBSTANCE: at the mouth of a well with horizontal borehole the bottomhole assembly is assembled bottom-up of a chisel, the right tube, calibrator, a return valve passing bottom up, then the bottomhole assembly is run down at the end of drill string up to commencement of interval of open horizontal borehole, circulation of washing fluid is generated by backflow with consumption rate of 8 l/s and simultaneous movement of the drill string with speed of 0.2 m/s at most in regard to the borehole with discharge of washing fluid through the drill string at the well mouth. Before extension of each drill pipe washing is performed in volume equal to 1.5 times volume of the drill string with assembly reciprocating per length of the drill pipe. In process of backflow washing the return valve is open and sludge from the borehole flows inside the drill string upstream the return valve. When discharge of washing fluid is stopped through the drill string, at the well mouth the string is removed from the borehole, at that the return valve is closed. At the string is removed from the borehole it is cleaned from sludge to a channel-type container. The above operations are repeated starting with assembling of the bottomhole assembly and finishing up with cleaning of the drill string from sludge during required number of times until the preset bottomhole is reached.

EFFECT: improved reliability and efficiency of permeability recovery for the bottomhole.

3 dwg