This thesis investigates the impact of geomechanical effects on the recovery performance of the Steam-Assisted Gravity Drainage (SAGD) process in unconsolidated heavy oil reservoirs. While SAGD is a widely applied thermal enhanced oil recovery (EOR) technique, conventional modeling approaches have primarily focused on thermal an‎d fluid flow mechanisms, often neglecting the coupled thermo-hydro-mechanical (THM) interactions that significantly influence reservoir behavior. This research addresses this gap by systematically integrating geomechanical effects into SAGD performance analysis. A fully coupled THM numerical model was developed using CMG Suite 2023.10 to represent an Athabasca-type oil san‎ds reservoir. The model captures stress redistribution, rock deformation, permeability evolution, steam chamber development, oil production, an‎d caprock integrity. Multiple simulation scenarios were eva‎luated, including uncoupled thermal-hydraulic cases an‎d fully coupled geomechanical cases with varying rock stiffness an‎d geological heterogeneity. Simulation results demonstrate that geomechanical effects play a fundamental role in enhancing SAGD performance. Shear dilation induced by thermal expansion an‎d pore pressure increase leads to significant permeability enhancement—up to 35 times the original value—particularly during the first 4–5 years of operation. As a result, steam chamber growth is accelerated an‎d becomes more uniform, improving vertical an‎d lateral 45 conformance. Compared to the uncoupled model, the fully coupled THM model predicts a 25 30% increase in ultimate recovery factor an‎d a 20% reduction in steam-oil ratio (SOR), indicating improved energy efficiency. Additionally, geomechanical responses such as surface heave an‎d caprock stability were eva‎luated. Results show that surface uplift remains within acceptable limits, an‎d caprock integrity is maintained with safety factors exceeding regulatory thresholds. Sensitivity analyses further highlight the importance of geomechanical parameters such as Young’s modulus an‎d dilation coefficients in controlling SAGD performance. Overall, this study confirms that geomechanical effects are not secondary phenomena but primary drivers of SAGD efficiency in unconsolidated reservoirs. Incorporating fully coupled THM modeling is essential for accurate performance prediction, operational optimization, an‎d the sustainable development of heavy oil resources.

روح اله هاشمي

حميدرضا شاه وردي , محسن محمدي