Publications

The Banyu Urip field has progressed from an exploration prospect to oil production since it was discovered in 2001, and the Banyu Urip geologic model has similarly evolved from a simple exploration model, through separate clastic and carbonate reservoir pre-development models, to a combined multi-reservoir post-development / early-production model. At each stage, a unique workflow was constructed to address specific technical problems. The current, interim multi-reservoir post-development / early-production model was built with a more simplified, easily modified, workflow to enable a quick and accurate update to the pre-development reservoir description with data from the development wells and associated production, both now and in the future. The changes included construction of pseudo-zones to eliminate pinch-out cells that can affect predicted fluid flow, a quick method to update the top-carbonate surface, a simple and easy-to-update approach to modeling the reservoir-quality regions, and seismically guided intra-carbonate layering. Results from the drilling campaign suggest that this approach was appropriate as incorporation of recent well data allowed a better prediction of the top of carbonate structure, reservoir-quality zones, porosity distributions and major drilling hazards. The other significant geologic model update concerns the distribution of excess permeability within the carbonate reservoir. Excess permeability has been observed from well tests, production data and the recent production logs. Permeability calculated from the production logs overall is higher than the core-based (matrix) permeability. Cross plots between porosity and production-log-derived permeability indicate that there are four main porosity–to-permeability transforms that correspond to reservoir-quality zones. These transforms are used to distribute the excess permeability throughout the field in both geologic and simulation models. This approach yields a better history match to the current production data.