A two-way coupled 4D geomechanical simulation was conducted for two adjacent deep-water fields, located in South East Asia, to investigate the impact of reservoir compaction over the production profile of the reservoirs. The results of the 4D geomechanical model were also used to calculate the stress path, surface subsidence and evaluate the risks associated with reservoir compaction over the life of the fields.
The 4D geomechanical model is a finite element (FE) model which was prepared from the structural geology model, surface seismic data, offset well geomechanical models and laboratory core tests. A Drucker-Prager/Cap material model was considered for the reservoir layers to calculate the compaction associated with pore collapse in high depletion zones. The 4D geomechanical model was two-way coupled with the reservoir dynamic simulation for predefined simulation steps over the life of the fields.
The impact of the reservoir compaction on the reservoir performance was evaluated by comparing the results of the coupled reservoir dynamic simulation against the uncoupled simulation. The results indicated that the impact of reservoir compaction and pore collapse is negligible for the expected level of depletion. The importance of conducting field-scale 4D geomechanical studies to have a better understanding of the reservoir response over the life of the field is demonstrated in this paper. The obtained results are particularly important for decision making in the field development planning stage.