METHOD FOR WELL DRILLING AND ASSEMBLY FOR ITS REALIZATION Russian patent published in 1994 - IPC

FIELD: construction of wells in lost circulation zones. SUBSTANCE: assembly has drilling bit, subs of pipe string and drilling bit. Installed in sub side surface is destructible membrane and seat and locking member are below membrane. When drilling is carried out in lost circulation zone, the locking member is dropped into drill string. Increased pressure destroys membrane and a part of flow is directed through sub side hole. Formed on hole bottom is accumulation of cuttings and thick mixture of cuttings and mud. Gauging members of bit force solid cuttings and mixture into well walls and formation pores are clogged to prevent loss of circulation. EFFECT: higher efficiency. 2 cl, 1 dwg