This chapter presents a comprehensive exploration of well integrity challenges specific to geothermal energy systems, emphasizing the extreme thermal and chemical environments that differentiate these wells from conventional oil and gas operations. Geothermal wells are routinely exposed to sustained high temperatures (>200 °C) and aggressive fluid chemistries rich in CO₂, H₂S, and dissolved minerals. These conditions impose severe stress on casings, cement sheaths, seals, and surface equipment, demanding specialized material selection, robust design, and tailored operational practices. The chapter begins by characterizing geothermal resources and their system configurations—including hydrothermal, Enhanced Geothermal Systems (EGS), and closed-loop designs—highlighting the diverse and often hostile downhole conditions. Design challenges include thermal stress cycling, strength degradation of materials, and cement stability. Thermal-mechanical modeling is introduced to predict casing expansion, annular pressure buildup, and cement cracking. Innovative cement formulations incorporating silica, elastomers, or self-healing properties are reviewed to improve resilience. The chapter also details the use of premium casing connections, thermal-resistant seals, and large-diameter designs essential for high-flow geothermal applications. Drilling and cementing geothermal wells introduce additional difficulties, such as poor mud displacement in high-angle holes, logging tool temperature limits, and slurry instability during placement. Operationally, corrosion, mineral scaling, and thermal fatigue represent persistent integrity threats. The chapter outlines monitoring strategies using Distributed Temperature and Strain Sensing (DTS/DSS), annular pressure surveillance, and temperature-compensated wellhead design to mitigate risks. Field case studies and figures demonstrate how thermal stress reversals, material degradation, and cyclic fatigue compromise casing and cement over time. Abandonment of geothermal wells introduces further complexity due to residual heat, chemically degraded primary barriers, and the difficulty of verifying annular sealing in high-temperature zones. The chapter concludes by framing geothermal well integrity as a high-stakes, long-term commitment requiring an integrated approach—from design to plug and abandonment—based on rigorous thermal analysis, tailored materials, and advanced monitoring technologies. It emphasizes the need for continued innovation to support geothermal’s critical role in a decarbonized energy future.

Geothermal Well Integrity

章节
发表日期：

2026年

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Ahmed Alsubaih,
Kamy Sepehrnoori

摘要

This chapter presents a comprehensive exploration of well integrity challenges specific to geothermal energy systems, emphasizing the extreme thermal and chemical environments that differentiate these wells from conventional oil and gas operations. Geothermal wells are routinely exposed to sustained high temperatures (>200 °C) and aggressive fluid chemistries rich in CO₂, H₂S, and dissolved minerals. These conditions impose severe stress on casings, cement sheaths, seals, and surface equipment, demanding specialized material selection, robust design, and tailored operational practices. The chapter begins by characterizing geothermal resources and their system configurations—including hydrothermal, Enhanced Geothermal Systems (EGS), and closed-loop designs—highlighting the diverse and often hostile downhole conditions. Design challenges include thermal stress cycling, strength degradation of materials, and cement stability. Thermal-mechanical modeling is introduced to predict casing expansion, annular pressure buildup, and cement cracking. Innovative cement formulations incorporating silica, elastomers, or self-healing properties are reviewed to improve resilience. The chapter also details the use of premium casing connections, thermal-resistant seals, and large-diameter designs essential for high-flow geothermal applications. Drilling and cementing geothermal wells introduce additional difficulties, such as poor mud displacement in high-angle holes, logging tool temperature limits, and slurry instability during placement. Operationally, corrosion, mineral scaling, and thermal fatigue represent persistent integrity threats. The chapter outlines monitoring strategies using Distributed Temperature and Strain Sensing (DTS/DSS), annular pressure surveillance, and temperature-compensated wellhead design to mitigate risks. Field case studies and figures demonstrate how thermal stress reversals, material degradation, and cyclic fatigue compromise casing and cement over time. Abandonment of geothermal wells introduces further complexity due to residual heat, chemically degraded primary barriers, and the difficulty of verifying annular sealing in high-temperature zones. The chapter concludes by framing geothermal well integrity as a high-stakes, long-term commitment requiring an integrated approach—from design to plug and abandonment—based on rigorous thermal analysis, tailored materials, and advanced monitoring technologies. It emphasizes the need for continued innovation to support geothermal’s critical role in a decarbonized energy future.