A New Approach to 3-D Synthetic Structural and Stratigraphic Basin Modeling: Impact Assessment of Evolving Structural and Sedimentary Architectures on Reservoir Connectivity and Performance

P.W. Bradbury¹, S.R. Freeman¹, S.D. Harris¹, R.J. Knipe¹, W.D. McCaffrey², Jaco H. Baas², and Gavin Lewis^3
1 Rock Deformation Research Ltd, Leeds, England
² University of Leeds, Leeds, United Kingdom
³ ChevronTexaco North America, Houston, TX

Current stochastic facies population methodologies rely heavily on incomplete statistical data coverage of the general geometry and more specifically the lateral continuity of various architectural elements. Deterministic approaches are often employed to constrain stochastic models in the form of flow boundary lines and flow vector surfaces. This new approach models geological processes to form geologically realistic structural and sedimentary geometries within reservoir simulation grids. The relationship between depositional geometries and active structure has an impact on reservoir connectivity not currently resolved by either stochastic or deterministic methodologies. This approach uses statistical data coupled with physical processes to build realistic stratigraphies within basin bathymetries incorporating synchronous synthetic basin evolution. Basin filling is controlled by various input parameters including source options, input velocities and background sedimentation rates. Turbidite flow within the basin is controlled purely by physical processes which naturally develop zones of flow reflection, ponding and onlap as well as variable rates of erosion and deposition. Synchronous basin evolution incorporates basin scale structural and stratigraphic grid modifications in the form of salt movement, folding, faulting, sediment compaction and basin subsidence. The geometry of the sedimentary bodies produced are a function of the flow regime in place and provide a more realistic solution than stochastic population techniques. Synthetically generated basin models can be directly input to reservoir flow simulators or may undergo further deformation. Structural models incorporating ranges of fault connectivities and orientations are merged with the stratigraphic grids to evaluate impacts on reservoir connectivity and performance. Initial results show significant variability in cross-fault flow properties and connected volumes calculated using a variety of clay mixing algorithms, structural geometries and sedimentary sub-environments.