Sushil Shetty

Workflow to Automatically Update Geological Models during Well Placement with High Angle and Horizontal Well Log Interpretation Results

We present a novel methodology for integration of high-angle/horizontal (HA/HZ) well data into 3D geomodels as a natural extension to well placement workflows. Log interpretation, typically done in 2D cross-sections, is based on 1-D automated inversion, yielding near-wellbore reservoir structure and properties. 2D cross-section, updated by inversion and further refined using 2D/3D modeling, is subsequently retrofitted into the geomodel so as to minimally perturb the original topology. Changes in positions/dips/azimuths of boundaries and faults, cell properties, and further local grid refinements are applied automatically. The updated geomodel honors high-resolution logs and low-resolution seismic/nearby wells data. We demonstrate this on a typical real-time well placement scenario. Electromagnetic log interpretation codes are integrated as a high performance computing (HPC) Web service into a geosteering/model update workflow. As the initial model, we use 3D geomodel constructed from seismic/vertical well data. A ―curtain‖ cross-section is extracted, edited based on 1D inversion, and further refined to match HA/HZ logs through 2D and 3D forward modeling, by changing properties/dips/layer thicknesses /fault positions, while preserving the original topology. Then, updated node coordinates and cell properties of the affected pillar grid region are calculated to optimally retrofit the changed 2D cross-section into the grid. These changes are then automatically applied to the 3D model. For quality control, we recompute the 2D cross-section from the refined geomodel. Ultimately, we arrive at the geomodel that honors both seismic and resistivity well-log data. The combination, in a single workflow, of physics-based log modeling codes, Services-Oriented Architecture, HPC framework, and the solver to optimally retrofit 2D cross-sections into 3D models, creates a qualitatively new opportunity for well placement engineers. This integrated workflow (1) maximizes the value of deep directional resistivity well-logs and real-time well placement interpretation by incorporating them into the source of data for building geomodels; (2) radically speeds up the model refinement loop by automatically calculating and applying the modifications to 3D reservoir model; (3) enables geoscientists to directly refine geomodels while geosteering. The latter has not been a standard practice, hindered by challenges of scale difference between geomodels and well-logs and lack of availability of efficient modeling codes.