Development of PDC bits for geothermal well drilling

Abstract

Polycrystalline diamond compact (PDC) bits are widely used in oil and gas well drilling. It is essential to develop PDC bits that have sufficient efficiency to drill hard, inhomogeneous, and fractured formations to expand the use of PDC bits in geothermal well drilling. A research and development project commissioned by Japan Organization for Metals and Energy Security was conducted, aiming at development of domestic PDC bits for geothermal well drilling. The development of PDC cutters and high-durability PDC bits and the performance evaluation of them through laboratory and field drilling tests are presented in this report. As a result, three predetermined numerical targets concerning rate of penetration, bit life, and gage loss, were considered to be sufficiently achieved in a field demonstration test of one of fabricated PDC bits. According to a provisional estimation, achieving all the numerical targets results in a reduction of 19% in the period required for drilling a 2,000 m well compared to drilling with roller cone bits. The manufacturing cost of the PDC bit was reduced to one-third through the follow-up research conducted subsequently after the project. The performance of developed PDC bits in laboratory and field drilling tests were analyzed using an ROP model.