INFLUENCE OF COAL ROCK HARDNESS AND CONFINING PRESSURE ON SPECIFIC ENERGY CONSUMPTION OF PDC BIT DURING GAS EXTRACTION BOREHOLE

Abstract

Specific energy consumption have a great influence on drilling performance of PDC bit in the process of gas drainage in soft coal seam. Study influence of coal rock hardness and confining pressure on specific energy consumption is very important. The mathematical model of specific energy consumption is built according to the coal rock cutting principle. Gas drainage drilling experiment table was built and Gas drainage drilling experiment was carried out under different coal rock hardness and confining pressure. The results indicate that specific energy consumption increase with the increase of coal rock hardness. Specific energy consumption increase with the increase of confining pressure. It provides a good theoretical basis for practical