Study on Thermo-Hydro-Mechanical Coupling and the Stability of a Geothermal Wellbore Structure

For processes such as water injection in deep geothermal production, heat transfer and fluid flow are coupled affect one another, which leads to numerous challenges wellbore structure safety. Due complicated structures, consisting of casing, cement sheaths, formations under high temperature, pressure, situ stress, the effects thermo-hydro-mechanical (THM) coupling crucial for instability control wellbores. A THM-coupled model was developed describe thermal, fluid, mechanical behavior sheath, geological environment around wellbore. The results show that a significant disturbance effective stress occurred mainly due excess pore pressure temperature changes during cold injection. gradually propagated far-field disrupted integrity structure. serious thermal concentration at junction cased-hole open-hole section. When difference between injected formation up 160 °C, maximum hoop tensile granite reached 43.7 MPa, twice strength, may increase risk collapse or rupture radial with 31.9 MPa concentrated interface casing can cause debonding cementing sheath. This study provides reference both prediction THM responses design drilling density development.