A Method for Assembling and Maintaining a Large Geologically Complex Geocelluar Model: Example from Elk Hills Field, California
Fields with many thousands of wells, active drilling programs, and complex geologic frameworks are inherently difficult to model in a geocellular framework due to conflicting or changing interpretations, variable data quality, time constraints, and restrictions imposed by the corner point grid. Common solutions are simplification and non-reproducible editing of the underlying data and interpretation. In the Eastern Shallow Oil Zone, Elk Hills field, California we built and maintain a large, relatively uncompromised geocellular model for use by the reservoir management team for simulation studies, reservoir surveillance, and development planning using a methodology that incorporated changing interpretations and data while simultaneously progressing with model construction. The underlying interpretation consists of approximately 165,000 stratigraphic picks and 3,200 fault cuts in 3,500 wells over an area of 20,000 acres. Thirty-six reservoir units, 41 non-reservoir units, and 52 normal faults are characterized in the model volume of interest. Erosional unconformities and stratigraphic pinch outs exist in a majority of what are thin bedded reservoir units. We developed a set of workflows and multi-user tools to (1) remove spatially redundant data; (2) identify interpretation errors based on stratigraphic position; (3) modify interpretation to be compatible with modeling software; (4) record and communicate interpretations to be modified and excluded until changes are complete; (5) document and implement changes to underlying data. An audit trail for each issue and solution is maintained and so that it can be repeated automatically each time the geologic model is updated. The result is a large geocellular model that is easily updated, reproducible, and well documented.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California