Core drilling in Tongting coal mine

Abstract:

By introducing and analyzing the characteristics of strata and lithology in the goaf area of the various sections of the Tongting coal mine in Anhui Province, the difficulties are pointed out in the process of drilling and coring. The relevant technical measures such as enlarging the borehole structure, optimizing the drilling tool combination, strengthening the mud performance maintenance were adopted. To deal with serious wellbore shrinkage, the borehole diameter was increased with reduced casing diameter to overcome the difficulties caused by shrinkage when lowering casing. Thickened cement grout was successfully used to deal with breakage of the φ114mm casing, serious stratum fractures and water leakage problems in the goaf. Finally seven boreholes were successfully completed in coal strata, which achieved good economic and social benefits.