OPTIMIZATION STEAM INJECTION IN X FIELD RESERVOIR HEAVY OIL WITH EVALUATION ANALYSIS OF GEOMECHANICS

Abstract

Heavy oil reservoirs located at shallow depths present significant challenges for enhanced oil recovery (EOR), primarily due to high viscosity, limited pressure containment, and increased geomechanical sensitivity. This study aims to optimize steam injection strategies in a shallow heavy oil reservoir through the integration of thermal and geomechanical analysis using the tNavigator simulation platform. The objectives include evaluating steam breakthrough timing, assessing stress and rock deformation, and identifying the most effective injection scenario to enhance oil recovery while maintaining reservoir integrity. The research begins by constructing a thermal-geomechanical model based on reservoir data from a shallow heavy oil field in the Sumatera Basin. Key reservoir and rock mechanics parameters such as Young’s Modulus, cohesion, friction angle, and thermal expansion were used to simulate deformation and failure potential through displacement vector and Mohr Coulomb failure index analysis. Sensitivity analyses were conducted injection temperature (140–400°F), water injection rate (200–800 stb/day), and viscosity validation in varying field 2000 cp – 5000 cp with scenario optimization. The results indicate that the higher injection temperatures induce greater stress differences within the reservoir rock, thereby increasing the risk of rock failure while higher injection rates increase oil recovery, they also lead to greater deformation and failure risk. Considering oil production, geomechanical safety, and water management, 350 °F steam injection scenario is concluded as the best and most optimum injection strategy. With analysis sensitivity the water rate injection 800 stb/day scenario yielded the highest oil recovery (6.4 MSTB) but approached geomechanical failure idex 0.98. Conversely, 200 stb/day-maintained reservoir stability (FI = 0.30) but resulted in lower recovery (2.9 MSTB). The 500 stb/day scenario was identified as the optimal condition, producing 5.2 MSTB with a stable FI of 0.34. In conclusion, the 500 stb/day injection rate represents the best trade-off between enhanced oil recovery and geomechanical safety. The validation, scenario optimum in different viscosity shows steam injection rate and temperature are optimized for medium-viscosity cases (100 cp – 2000 cp), they may not be universally effective for fields with higher viscosity oils 5000 cp (or more). Therefore, while the scenario is validated as favorable for lower-viscosity applications, it becomes less effective and potentially being the limitation strategy when facing heavier crude conditions. Keywords: Geomechanics, Heavy Oil, Mohr-Coulumb, Injection