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The use of reservoir simulation coupled with geomechanics to model physical phenomena such as compaction, subsidence, induced fracturing, enhancement of natural fractures and/or fault activation, SAGD recovery etc.., has been increasing. Among different methods investigated by researchers. The iterative explicit method appears to be the preferred method for field-scale simulation. This method is a loose coupled approach between a reservoir and a geomechanical simulator. At user-defined steps, the fluid pressures are transmitted to the geomechanical tool which computes the actual stresses and reports the modifications of porosities and permeabilities back to the reservoir simulator. In the classical iterative scheme, at each stress equilibration step, the reservoir simulation needs to be restarted from the previous converged step. This scheme can be difficult to implement within an industrial IT environment. This paper presents a new iterative scheme which allows:any reservoir simulator,to be coupled with any nonlinear FEM package for the stress analysis without any limitation on the functionality of either simulator. The convergence of this new scheme is discussed and results are presented for three cases described below. The first case is a validation case used by other SPE papers. The second case is a synthetic model of a highly compacting reservoir sensitive to water saturation. The third one is a full field reservoir model. Faults are modeled inside the reservoir CPG grid and also inside the geomechanical mesh using specific cohesive elements. In all cases, convergence is achieved in a few iterations and results are comparable to those obtained with previously tested methods. The feasibility of the proposed coupling approach using industrial software is proved. Another advantage compared to the standard iterative scheme is the ability to compare production profiles over the complete time history at the end of each geomechanical iteration. The reservoir engineer evaluates the coupling effects and ends the iterative process when production curves variations between two iterations are no longer significant. Introduction The importance of geomechanics in problems such as wellbore stability, hydraulic fracturing and subsidence is well known. In recent years, there has been growing awareness of the importance of the link between fluid flow and geomechanics in the management of stress sensitive reservoirs 1–9. New needs for coupled simulations appear such as assessing the integrity of the overburden for heavy oil recovery using thermal mechanism (SAGD technique, ..) or for acid gas injection. Standard reservoir simulation of compaction drive accounts for nonlinear porosity changes determined from uniaxial strain tests on cores. In many cases, laboratory-derived compressibility must be adjusted to match the contribution of compaction to total hydrocarbon recovery. Geomechanical effects such as stress arching and non-unique stress path are among the causes of discrepancy between laboratory-derived and field compressibility factors. If compressibility varies linearly with the mean reservoir pressure, then predictive reservoir modeling can be achieved without coupling between stress and flow. However, geomechanical effects are rarely linear for a number of reasons. These include load variations due to modification of pressure, temperature and saturation, change of the mechanism of production, progressive activation of faults and fractures that affect mechanisms such as stress arching and a non-linear stress path. Unlike standard compaction drive simulation, there is no simple linear method to account for the effects of stress on permeability especially for fractured systems, where the changes of permeability might be directional, localized and strongly non-linear.

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