Custom PDC Bits Significantly Increase Drilling Performance in Tauhara Geothermal Drilling Project, Taupo, New Zealand

Abstract

Challenge: The introduction of a PDC bit into geothermal applications is always a challenge and raises questions about the bit’s durability, directional response and most importantly the economic viability of such bits. This paper is going to focus on addressing two sets of challenges associated with drilling a 20.75” section through the Huka Falls, Waiora and Racetrack Rhyolite formations, and a 12.25” section through a very hard volcanic and sedimentary rock. Both of the sections were historically drilled with roller cone bits. Methodology: This paper is going to cover PDC drill bits design, cutter selection and root cause analysis of drilling disfunctions and other limitations affecting the overall drilling efficiency. It will also include drilling parameter sensitivity, the drilling practices utilized to address the challenges and reduce the risks of bit damage, improve overall drilling performance and the economics for both sections in question. Results: Based on the above project, two bit designs were developed, tested and fine-tuned for the application. In this paper the results of these tests will be illustrated, and future development potential outlined.