CH_01
From Conceptual Model to Feasibility to Well Integrity
Geothermal projects are exposed to subsurface uncertainty and heavy up-front cost, and two decisions weigh heavily: committing to drilling on the conceptual model, and designing wells for the heat and chemistry they will meet. This Geologic® work addresses both. It proposes an integrated workflow that links the initial conceptual model to a feasibility-level assessment through four staged phases, each closed by an explicit go or no-go decision, and it reviews how to keep geothermal wells sound from drilling to production.
The workflow combines magnetotelluric imaging, geochemistry, temperature gradient drilling and numerical reservoir simulation with play-based portfolio methods, Monte Carlo uncertainty analysis and machine-learning surrogate models; it is a methodological synthesis rather than a single field case. For the wells, production zones can run from 160 °C to over 300 °C, beyond conventional oil fields, with corrosive gases and fluids ranging from alkaline to highly acidic, so casing, drilling fluids and cement must be designed with heat as the governing load. Conventional polymer drilling fluids are limited to circulating temperatures of around 90 °C, and a preventive approach to integrity is recognised as more cost-effective than reactive repair.