Publications

The Kedung Keris field is located in the Cepu block of the East Java basin. Similar to the giant Banyu Urip field, the reservoir is within an isolated Oligo-Miocene carbonate build-up. Rapid subsidence and a sea-level rise during the Burdigalian to Langhian (Early to Middle Miocene) time triggered a major back step of the build-up and eventually the final drowning of the carbonate; somewhat earlier than the build-up at Banyu Urip. Three dimensional seismic data covers the study area. Detailed analysis of the seismic data, well log data, and nearby field analogues enable the interpretation and mapping of reservoir quality regions (RQR) within the field. The interpretation of RQRs is a new approach for predicting reservoir parameters, such as porosity and permeability; throughout the Cepu block, that includes the Kedung Keris and Banyu Urip fields. The RQR prediction integrates the environment of deposition (EOD) interpretation as well as the diagenetic overprint. A detailed seismic facies interpretation was conducted using 3D PSDM data. Five seismic facies are apparent: 1) mounded, 2) chaotic, 3) parallel to sub-parallel, 4) prograding and inclined, and 5) individual bright amplitude bodies. These can be correlated to specific EODs, reef complex, platform interior, leeward / prograding margin and windward margin respectively. At Banyu Urip, the seismic facies / EODs are tied to different log stacking patterns, their associated reservoir parameters and diagenesis. By using Banyu Urip as an analogue, the porosity and permeability at Kedung Keris can be estimated for all five seismic facies although only one well intersected two of the four EODs. The RQR methodology is a powerful approach for predicting reservoir parameters throughout the Kedung Keris field by integrating well-log with seismic data, modern with nearby field analogues, and supported by a good understanding of geological concepts.