۴D geomechanical simulations for field development planning

۳D and ۴D geomechanical can be time-consuming to build and calibrate. However, once such a model is built, it is relative straightforward to use this model for various field development and management applications. In so doing, the return on the initial investment of time and effort in the creation of a ۴D geomechanical model can be substantial. I present a case study where a ۴D geomechanical model of a deepwater turbidite field under water flood is used to: Assessment of wellbore stability for drilling inclined infill wells after a stuck pipe event  Calculation of maximum allowable injection pressures during hydraulic stimulation to avoid out-of-zone growth of stimulated fractures, and evaluation of risk of fault re-activation during a range of production scenarios for pressure support in order to establish safe operational limits for pressure support. Model building uses seismic inversion volumes to constrain a geological facies model, followed by upscaling to a reservoir simulation model and history matching. Similarly, a ۳D geomechanical property model is built to the seafloor. The calibration of the pre-production stress state of the geomechanical model comprises of matching the results of ۳D finite element stress field calculations to ۱D wellbore models. The calibration uses a novel method of linking tectonic strain terms in poro-elastic equations in the ۱D and ۳D models. Production and injection processes are the computed using a fully coupled finite element based geomechanical flow simulator, solving multi-phase (black-oil) fluid flow and geomechanics equations simultaneously on the same computational mesh. The computational mesh is optimized for geomechanical predictions of wellbore and fault stability.