METHOD FOR WELL CONSTRUCTION Russian patent published in 2013 - IPC E21B7/00 

FIELD: mining.

SUBSTANCE: in process of production well drilling before drilling-out of the horizon with cavings, well tightness is inspected. A boring bit is lowered onto drill pipes, a clay mud containing inert long-fibre fillers is injected into the well. The first clay mud in the well is replaced with the clay mud without long-fibre filler during stroking of a drilling string. The inclined well bore is drilled with a zenith angle of 74-77° in cavings of the Kynovian horizon. The flushing fluid is a gel-emulsion solution "MULTIBUR". As pressure of flushing fluid injection increases, the drilling assembly is unloaded, flushing is carried out with gradual increase of flushing fluid flow and with tool stroking. The assembly is again loaded to repeat the operation until the pressure of the flushing fluid injection reaches 10-11 MPa. Prior to every adding of a drill pipe length to the drilling string, the well is flushed. After reaching the previously drilled bottomhole, deepening is continued until coarse sludge is no longer available on lattices. A wiper trip of the well hole is carried out with raising of the tool above the Kynovian horizon and lowering to the bottomhole with subsequent removal of the drilling tool. The capital string is lowered, the casing string annulus is cemented.

EFFECT: possibility to build wells stretching via caving zones at a large zenith angle.

1 dwg, 2 tbl