METHOD OF RESTORATION OF WELLBORE PASSABILITY AFTER WALL CAVING Russian patent published in 2001 - IPC

FIELD: drilling of oil and gas wells, particularly, restoration of wellbore passability after wall rock caving. SUBSTANCE: method includes assembly of bottom-hole string consisting of drill bit, drill collar, drill pipes. Said assembly is run into well, given rotary motion and circulation is initiated. Lowering of bottom-hole string with circulation is carried out to zone of rock accumulation and landing on it. Then, bottom-string is separated from rock, given rotary motion and quantity of injected drilling mud is reduced. Large rock pieces are broken by drill bit from suspended position. In case of wedging, drill bit is lifted above caving zone and process of breaking is repeated. After drill bit passing through a part or through all caving zone, circulation is intensified to maximum without passes zone to wash out fine cuttings from well up to full elimination of drawing-in and wedging. EFFECT: higher efficiency of restoration of well bore passability after wall caving.