Publications

The Gunung Kembang Field produces from carbonates of the Baturaja Formation. The field is contained within an elongated anticlinorium that is over 7 km in length and 3.5 km in width. A total of 10 wells have been drilled to-date, consisting of several vertical wells, pilot holes and horizontal wells. The field has a maximum reservoir thickness of 80 meter, and contains a gas cap with maximum gross thickness of 40 meter, underlain by an oil column with thickness that ranges from 8 to 12 meter. Problems appear in this reservoir when the oil is produced, due to the thin oil column. The field has a strong gas cap drive with weak aquifer support, resulting in a high GOR and low oil recovery. This is a challenge for recovery optimization. To address this, we applied the AVO-Inversion technique for reservoir characterization of this field. The objectives were to estimate the lateral and vertical extents of the oil column, and to map the oil-bearing carbonate facies distribution using seismic and wireline log data from the field. Results from AVO-Inversion, along with carbonate facies interpretation, are used to generate an updated geological model that in turn is used for reservoir modeling and flow simulation. A Lambda-Mu-Rho cross-plot using data from well logs shows that the gas, oil, and brine values are populated in separate clusters. This suggests that extraction of Lambda-Rho and Mu-Rho parameters from seismic data can lead to fluid identification. Similarly, the Mu-Rho parameter was determined to be diagnostic of lithology. Accordingly, AI and AVO inversion were performed on 14 2D lines from the field, yielding maps of porosity, and Lambda-Rho and Mu-Rho parameter values. When calibrated against the results of well log analysis, these parameters in turn yielded maps of the distribution of oil-bearing carbonate reservoir facies. Correlation between fluid-sensitive, and lithologysensitive elastic parameter maps suggest that the oil column is contained within the better carbonate reservoir facies. Drilling of two development wells is planned for next year, using an updated reservoir simulation model based on the AVO inversion results, with a revised field development plan.