Enhancing Geothermal Wells Integrity: Key Considerations and Challenges from Drilling to Production

Abstract

Abstract Geothermal energy is widely acknowledged as a renewable and sustainable energy source, capable of reducing carbon footprint, with great potential in the global energy sector, particularly in power generation. Geothermal wells are the key infrastructure that enables the extraction of thermal energy from the subsurface. To ensure the long-term productivity and performance of geothermal systems, it is critical to maintain the integrity of geothermal wells throughout their lifecycle, from drilling to production. This paper provides an overview of the key considerations and solutions associated with maintaining geothermal wells integrity through a case study of a prospective geothermal exploration campaign in the Middle East. Maintaining well barriers integrity presents a significant challenge due to the degradation of drilling and completion fluids, fluids property variations, and cement strength degradation from pressure and temperature cycling during production. Other integrity concerns include casing expansion at high temperatures, buckling and decoupling of casings, casing corrosion, wellhead thermal expansion, and scaling. Recognizing downhole conditions, structural geology, geochemistry, geomechanics, subsurface temperature profiling, and rock-water-fluid interactions offer solutions for addressing challenges associated with geothermal activities. This knowledge is utilized to determine the most efficient wellbore design, customize drilling and completion fluids design with laboratory testing to simulate the anticipated bottom hole temperature, identify the optimal mud weight window, select casing materials and completion components, and aid in drill bits selection. Robust primary cement and cement plugs design, along with best practices during cementing operations, are present to ensure effective zonal isolation, minimize risks, and maintain long-term well integrity. Additionally, pressure testing, cement bond evaluation, and temperature monitoring are critical for identifying potential leaks or failures in the well system. In conclusion, ensuring the integrity of geothermal wells from drilling to production is essential for the long-term performance and productivity of geothermal systems. This paper will review casing selection, drilling, and completion fluids design, cementing design and practices, and proactive monitoring to achieve optimal structural integrity throughout the operational lifetime of the well. By sharing these insights, this paper provides a summary of current solutions to geothermal well integrity issues with the objective of promoting sustainable and reliable resource development.