METHOD FOR DRILLING SUPERDEEP BORE-HOLES Russian patent published in 1999 - IPC

FIELD: mining industry. SUBSTANCE: method relates to technology of drilling deep and superdeep bore-holes. According to method, lowered into bore-hole preliminarily filled with washing fluid is drilling tool which is not filled with fluid. Washing fluid is continuously or periodically added up to bore-hole head. Adding of fluid is started when external pressure is less than crushing pressure P_ex< P_c. At reaching of depth equal to 2500 m, adding of fluid inside drilling string is discontinued. Drilling tool which is not filled with fluid to aforesaid height is lowered to bottom hole, productive bed is drilled up, washing with fluid is continued with subsequent pressure-forcing it down from top to bottom through drilling pipes, sludge catching pipe, lock-turning valve, throttle, and drilling bit with application of special catchers and movable valve up to stopping of inflow of fluid into drilling pipes from annular space. After that, drilling tool freed from washing fluid is lifted up. Application of aforesaid method allows for reaching required depth of drilling superdeep bore-holes together with reduction of material and power cost. EFFECT: higher efficiency. 5 cl