Publications

Proven reservoir exists on the western part of Bawean high and the Muriah Trough by the gas discoveries at Kepodang and Lengo structures. These discoveries and re-evaluation of the well status result will give the pictures of the hydrocarbon presence and attract the explorationist to do more exploration activities in this region. A petroleum study was undertaken based on a gas composition, gas isotope, geochem from well data, log and seismic. The result shows an active of biogenic source develop in the Muriah Trough, Bawean High, and East Florence Basin where a series of coal beds and shale have been encountered by a lot of wells. The CO2 content is one of the risk element to explore the hydrocarbon potential in this region, proven by several exploration wells which have relatively high CO2 concentration both in clastics and carbonates section. Mostly the δ13CCO2 values suggested that its came from inorganic, while some wells shows the CO2 may derived from organic. The variation of CO2 source is causing the prediction of the inert gas require more observation by conducting geochemistry plot, geothermal gradient mapping, and seismic interpretation. Magmatic activities is interpreted as the main CO2 source in this area. The geothermal gradient (GG) beneath the ‘uncompacted sediment’ from wells have been used for CO2 risk prediction. The pattern of basement configuration, local magmatic activities were used as a basis to generate GG map and produced the picture of the area which has relatively high risk of CO2 is located close to the volcanic activities (Muriah, Lasem, and Bawean island), whereas the area which relatively have less CO2 risk is located in the area close to Lengo, Kepodang and the northern part of Bawean High. The CO2 risk for each play may have different picture, and it will need more observation on each element of the petroleum system.