Simulation study of new directional drilling PDC bit used in coal mine. Issue 3 (4th May 2017) - Sun, Rongjun
Abstract: During directional drilling, when drilling in hard and multi-interbedded formation, the ordinary flat-bottomed PDC bit wears seriously, in order to solve this problem, a new type of directional drilling PDC bit (straight angle drag PDC bit) is developed, and numerical simulation method is used to analyze the working characteristics of straight angle drag PDC bit. Simulation results show that, comparing with the ordinary flat-bottomed PDC bit, axial force needed by straight angle drag PDC bit reduces by up to 36%, and rock breaking efficiency increases nearly 50%. Also, Φ96 mm straight angle drag PDC bit is produced and field test is carried out; field test results show that: comparing with flat-bottomed PDC bit, bit life expectancy of straight angle drag PDC bit increases more than three times, and rock breaking efficiency increases about two times. So, when drilling in hard and multi-interbedded formation in the process of directional drilling, straight angle drag PDC bit helps to improve bit life and rock breaking efficiency and finally reduces drilling cost.