Prognosis on Potential Drilling and Well Integrity Risks Associated with Developing KSA's Geothermal Resources

Abstract Efforts focusing on developing geothermal energy in the Kingdom of Saudi Arabia are increasing and drilling operations of geothermal wells are being prepared for. This paper will provide an overview of geothermal energy resources in the Kingdom and an analysis of the potential drilling and well integrity risks that could be faced while developing geothermal resources in the Kingdom with a focus on medium and low-enthalpy geothermal systems. The paper uses drilling data obtained from a massive drilling campaign of geothermal wells and applies the experience gained and lessons learned from this drilling campaign in the prognosis for potential drilling and well integrity risks of drilling geothermal wells in the Kingdom of Saudi Arabia. It will also provide a literature review on the available geothermal resources in the Kingdom of Saudi Arabia, with a focus on medium and low enthalpy geothermal systems, and classify such resources geographically and in terms of economic feasibility and possible geothermal energy utilization and venues of applications. The study demonstrated the availability of vast geothermal energy resources in the Kingdom of Saudi Arabia. Such resources are classified into three main categories. First and most economically feasible to be developed are the high enthalpy geothermal energy resources which are present in radiogenic granites in the Arabian Shield rocks with a total area of 161,467 sq. km. The high heat flow in this system is associated with the radioactive decay of some radioactive minerals (Uranium, Thorium, and Potassium) existing within the granites. Another high enthalpy geothermal system in the Kingdom is the volcanic rocks (Harrats) within the Arabian Shield with a total area of 90,000 sq. Km. Some Harrats were found to be associated with dike intrusion and magma chamber appearing at about 8 km below the Harrat (Lunayyir). Hot springs in the western coast are identified as medium enthalpy geothermal systems and Clastic deposits are classified as low enthalpy geothermal systems available across the country. Main identified drilling risks are lost circulations cement placement. Other important factors affecting the well integrity are mainly casing selection, well design, and pump selection. The study concludes that considering the vast and geographically diversified geothermal resources in the Kingdom and with careful consideration of the drilling and well integrity risks associated with geothermal wells, the Kingdom is set to start an interesting and successful journey in developing its geothermal resources. This paper will be an important reference for developing geothermal resources in the Kingdom of Saudi Arabia in terms of drilling-associated risks and recommended mitigation practices. It will also provide an overview of the horizons for developing geothermal resources in the Kingdom of Saudi Arabia.