Using relations between stress and fluid pressure for improved compaction modelling in flow simulation and increased efficiency in coupled rock mechanics simulation

The conventional compaction model used in reservoir simulators defines compaction as a function of fluid pressure, whereas, in reality, it is a function of effective stress. The interrelationship between fluid pressure, effective stress and reservoir parameters (materials distribution, geometry, production scheme) is investigated. By modifying the conventional concept of flow simulator compaction a predictor is constructed for the rock mechanics computations in a coupled flow–rock mechanics simulation. This predictor reduces the time to converge the stress computations by reducing or eliminating the number of pore volume iterations in the coupling scheme. Overall computing time is thereby reduced considerably, while maintaining accuracy in the stress computations. Additionally, the compaction state in the flow simulator will be more accurate than in a conventional iterative coupling scheme.