METHOD FOR OPENING PRODUCTIVE BED OF LOW BED PRESSURE Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this is aimed at retaining natural permeability and collector properties of productive bed with low bed pressure. Bore-hole is drilled down to roof of productive bed, then intermediate casing string is lowered into bore-hole and cemented. Drilling string is lowered into bore-hole at closed locking and turnable valve which isolates inner space of drilling string from delivery of drilling mud. When drilling string is rotated by rotor, locking and turnable valve is opened and drilling mud under hydrostatic pressure of liquid column in bore-hole goes from under drill bit inside drilling string, thus ensuring back flushing of bottom-hole. In opening productive bed of large reserve capacity, circulation of drilling mud can be achieved by adding drilling mud into bore-hole at its head and pumping it out from inner space of drilling string into circulation system. EFFECT: higher efficiency. 1 cl, 1 dwg