An Open-Source Wellbore-Stability Modelling Framework for Geothermal Wells: Linking Failure Mechanisms, Evidence, and Lifecycle Decisions

The economic viability of geothermal energy depends on wells that can be constructed and operated reliably. Wellbore instability can delay drilling, require remediation, and interrupt operation. Stability modelling supports risk reduction when its mechanisms and input requirements match the formation, loading history, well geometry, and engineering decision. This critical review compares petroleum and geothermal evidence across drilling, completion, injection, operation, and intervention. We distinguish measured from simulated outcomes, calibration from independent testing, and rock stability from casing and barrier performance. Connected fractures can control circulation losses below an intact-rock fracture limit. Cold injection changes rock and barrier stresses, while long-term deformation is less well constrained at well scale. Strength criteria and bedding assumptions can also change pressure-window predictions. We develop a conditional model-selection framework and companion tool that connect well conditions to model families, required inputs, and observations for testing. Retrospective demonstrations and case assessments examine mechanism coverage and interpretation, including two sources excluded from rule development. Weak-material and fines-transport conditions are explicit, while casing diagnosis requires a separate justification for stress modelling. The outcome-informed assessments establish neither predictive accuracy nor operational benefit. Independent testing against drilling, injection, and intervention observations remains necessary.