De-carbonization and carbon utilization for subsurface energy transition: Introduction

The exploration, drilling, and development of high-temperature hydrothermal geothermal resources usually borrow ideas from the oil and gas industry. However, some techniques in the oil and gas industry are not entirely applicable for geothermal resources due to the difference in geological conditions and exploitation objectives. This paper briefly compared and analyzed the differences between high-temperature hydrothermal resources and oil & gas resources in exploration, drilling, and reservoir engineering to improve subsequent hydrothermal exploitation efficiency. The exploration of geothermal resources aims to identify high-temperature rock/fluid, and the improved electromagnetic method is mostly adopted to identify geological structures around geothermal resources due to its low cost. As for the seismic exploration primarily used in the oil & gas industry, it is difficult to interpret the rock associated with high-temperature geothermal activity, except of the high cost and time-consuming. Different from oil and gas wells, geothermal wells have large borehole radii and high requirements for casing corrosion resistance. Low-density drilling fluid is often used due to the lost circulation. Open holes with liner mostly complete conventional geothermal wells. For the dynamic development of geothermal resources, well test in the oil and gas industry can be used, but the material balance and empirical method in oil reservoir engineering are no longer suitable for dynamic analysis of geothermal resource development, and the real-time numerical simulation combined with field data is a more effective method for geothermal resource development.