The Role of Geomechanics in Integrated Forward Modelling of Geological Processes

ABSTRACT: Predicting natural fractures is increasingly important, not just for oil and gas, but also for new energy applications such as geothermal energy extraction and CO2 storage. Accurately predicting 3D distribution, timing of formation and orientation of natural fractures, developed during the structural evolution of reservoirs, is crucial for the mechanical integrity of CO2 storage sites, the success of geothermal systems, and enhancing oil and gas reservoir productivity. A novel approach, called Paleo-Geomechanics (PGM3D), has been developed, integrating (coupling) geomechanical simulation with forward modelling of sedimentary processes, in an enhanced Geological Process Modelling (GPM) workflow. With this integrated approach, sedimentary depositional architecture may be solved by explicitly simulating multiple physical processes involved in reservoir formation. Such processes include sediment deposition, diffusion and transport, carbonate growth, diagenesis, tectonics, erosion, and rock deformation. The effects of rock failure and changes in the existing stress field, taking place during depositional and burial evolution, are also considered. The newly developed PGM3D approach has been applied to several contexts, including simulating sandbox experimental deformation, carbonate growth through geological times, and in a real field case study. Results showed that PGM3D could predict the fault pattern observed from a sandbox experiment under extensional loading. Furthermore, the PGM3D workflow, preliminarily applied to a real field case study, was able to successfully predict the natural fracture distribution in the reservoir, matching over 68% of the interpreted image log fractures from the analyzed wells.