Publications

The offshore Northeast Java Basin is one of the largest basins in Indonesia with complete hydrocarbon systems from Middle Miocene Tuban formations to Pre-Tertiary basement formations and is located on the southeast margin of Sundaland which is dominated by a series of Northeast trending basement highs and intervening half - grabens. In the Pangkah Field, Carbonate Oligo-Miocene has a diverse property of reservoir and geological complexity due to reservoir heterogeneity and thickness variations. Many of productive carbonates have widely varying proportions of primary and secondary porosity, between high and low porosity reservoir adding more challenges to determine facies classification. To resolve the challenges in characterizing in complex carbonate system, an integrated work was developed that consists of combination of 3D stochastic inversion and comprehensive well data analysis. Analysis based on 3D stochastic inversion can be used to measure uncertainty in facies prediction and distribution. While analysis based on well data provides a good calibration of reservoir properties. The first step of stochastic inversion application is to analysis vertical properties variation derived by well and horizontal properties variation derived by seismic using a variogram analysis based on Bayesian theorem to measure reservoir distribution and facies classification uncertainty. Once facies have been generated, well logs were cross-plotted and calibrated with core data using neural network probabilistic. Neural network probabilistic shows several facies distribution around the area of study. The result suggests potential carbonate pay zone (carbonate build up) in Kujung I. These analyses also improve our understanding of the reservoir complexity, enable to interpret high porosity carbonate relates to low impedance value, while low porosity carbonate relates to high impedance value. The stochastic inversion methodology is proved and delivered better resolution by generating three facies than deterministic inversion which resulted only two facies in Pangkah field. This study has high impact to reduce uncertainty of reservoir properties in exploration and development strategy and could be deployed in the field with similar problem.