High-Temperature Measurement-While-Drilling Tools for Oil/Gas and Geothermal Drilling: Current Trends, Future Directions and Potential Impacts

Abstract Geothermal energy is used in more than 20 countries worldwide and is a clean, reliable, and relatively abundant energy source. Nevertheless, to make geothermal energy available anywhere in the world, technical and economic challenges need to be addressed. Drilling, in particular, is a technical challenge and constitutes a significant part of the geothermal development cost. As drilling goes deeper in search of oil and gas, bottomhole environmental conditions are reaching temperatures of 250°C and pressures of 30,000 psi. Similarly, in geothermal drilling, downhole conditions can easily exceed 200°C and reach 400°C in extreme cases. The U.S. Department of Energy (DOE) initiated various research-and-development (R&D) programs to push the limits of downhole electronics, including 175-200°C Measurement-While-Drilling (MWD) in the late 1990s and 300°C MWD and directional drilling systems in the late 2010s. This paper provides a comprehensive review of past R&D programs aimed at developing high-temperature drilling systems, describes the current state of available high-temperature technologies, MWD, and drilling systems, and analyzes future trends and needs for high-temperature cost-effective and reliable drilling systems, which enable us to tap into geothermal wells exceeding 250-400°C.