TECHNOLOGY TO CLEAR HORIZONTAL WELL FROM SAND PLUG IN PROCESS OF OVERHAUL Russian patent published in 2001 - IPC

FIELD: oil and gas production industry. SUBSTANCE: technology includes lowering of flexible tubing string into well. Depth of tubing string lowering is fixed. Clearing agent and foam-forming fluid are pumped through tubing string. Gas is pumped under pressure not exceeding that of pressure test of operational string. Foam-forming fluid in pumped through pipe clearance in the calculated amount. Portion of foam-forming fluid is forced through to face by inert gas till pressure jump is recorded across well-head. Value to which pressure across well-head should be dropped is calculated to form controllable depression on face. Sedimentation is transported by means of circulation of additional portion of foam. Additional portion of foam is supplied from well-head over flexible tubing string. If pipe clearance is shut portion of foam is forced through by inert gas into cleared interval of productive stratum under pressure not exceeding that of pressure test of operational string. Flexible tubing string is lowered through length of cleared interval. If pipe clearance is open face is blown through by inert gas. Cyclicity of process is determined by established lowering of pipes. EFFECT: increased efficiency of clearing of horizontal shafts from sedimentation, prevention of destruction of terrigenous collector and ruling out the possibility of muddying of face zone.