| Title | How to design, iterate and continually improve PDC drill bits for geothermal drilling |
|---|---|
| Authors | E. Krause |
| Year | 2024 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Drill bit design, offset analysis, geothermal drilling, performance improvement, PDC bits, continuous improvement, drilling optimization |
| Abstract | Geothermal Drilling is a high-cost operation and has a large upfront cost to any new power station project. Drilling a well requires setting a series of casing strings that are drilled to a suitable depth to provide pressure containment of the surrounding wellbore fluids. The production section is normally a longer open hole section and is drilled to access a geothermal reservoir. This is typically the most challenging section to drill and complete. Successfully drilling each section, requires an understanding of the geology, wellbore and formation hazards or challenges as well as the directional objectives. A wholistic approach is required to assess the optimum drilling strategy to complete the section with minimal cost. This is usually achieved by minimising drilling days in the form of increased rate of penetration (ROP), however can also be achieved by minimising drilling tool wear and reducing open hole risk and potential hole problems. This paper focuses on Polycrystalline Diamond Compact (PDC) drill bit design, selection and iteration processes to increase rate of penetration and subsequently reduce cost per meter drilled in geothermal operations. It will detail offset analysis techniques, dull grading and cutter failure mechanism recognition, drill bit manufacturer selection, continual improvement design iteration processes and drilling parameter optimisation. A good geothermal drilling strategy is balanced by utilising a well-designed custom drill bit, followed by suitable bottom hole assembly (BHA) selection and then drilled with ideal parameters – weight on bit, flow rate & revolutions per minute (RPM). The output of successfully completing this, results in smoother drilling, a bit that stays sharper for longer, and less accumulative tool & drill string wear by minimising on bottom drilling hours. This paper will demonstrate how to analyse and execute a custom drill bit design and drilling strategy that will suit your field and application. |