Key technology of drilling the borehole of 1 200 m deep in a coal mine in Xinjiang

Deep hole drilling is of great significance for deep prospecting. According to the special geological conditions of coal measures strata in a mining area of Xinjiang, roller diamond bit with the matrix of hardness HRC25~HRC36, diamond bit, suitable drilling parameters were chosen, solid phase-free gelatin mud and mud with low solid phase were used to protect borehole, 1 200 m deep hole drilling with wire line coring was ensured, good practical drilling experience was obtained. At the same time, attention was paid to selection and installation of core-catcher spring, the daily safety management of drilling machine and tools was enhanced to prevent downhole troubles induced by improper management.