Bunyu Tapa gas field is located on the western edge of Bunyu Island, approximately 12km northwest of Bunyu Nibung oil field, is the main gas producer for Bunyu Methanol plant. lnitially, the Bunyu Tapa sands were believed to be deposited as a blanket type sheet sand, but after drilling twenty-one wells in this field it is obvious that these sands lack lateral continuity. The Bunyu Tapa reservoir sands were deposited in a deltaic environment. Several wells which were producing gas close to the structurally high western edge of this field are exhibiting a high water cut. This water production is not expected in a deltaic lens environment, especially since these wells are up dip to other gas producing wells. This Bunyu Tapa reservoir modeling study is an integrated investigation of 2-D seismic data, electric logs, dipmeter, petrophysical analysis and production history data. The results of this integrated study shows that the sands were deposited as distributary channel sands across the field and extend off-shore. Structurally, the wells on the western edge are in fact on the eastern flank of a north-south trending anticline, close to the gas/water contact, and are separated from the eastern wells by north-south trending normal faults. In the near future, as a result of this study, a deviated well is planned to evaluate the off-shore area to the west.
Authors : Susanto Budi Nugroho & Dwi Mandhiri