Publications

The “J field is a tall carbonate buildup situated on a broad Oligo-Miocene age carbonate platform in the East Java Basin. The discovery well encountered a gas column in excess of 1400 ft and a thin oil column. Further appraisal drilling is required to determine the extent of the oil column. This paper describes how seismic inversion has been used to condition a geologic model and to directly estimate porosity in order to facilitate optimal placement of subsequent appraisal drilling. A number of fit-for-purpose solutions and initiatives were investigated to tackle specific issues related to seismic inversion. These included: the use of amplitude balancing to address the variability of seismic amplitudes related to land acquisition artifacts and shallow gas, and merging, guided by carbonate facies interpretation, of impedances from seismic velocities with well based impedances, to derive the low frequency model. Well-based rock property analysis helped relate P-impedance with porosity. Frequencies in seismic data are too low to capture reservoir scale heterogeneity that could be important from a reservoir performance perspective. A correlated noise attribute generated using Sequential Gaussian Simulation (SGS) was added to the seismic scale porosity to provide the subseismic heterogeneity. Porosity ranges from 0 to 35%, with an average porosity of 19% in the hydrocarbon leg. The final porosity model was used to condition permeability and saturation attributes. ExxonMobil proprietary techniques and software were used to upscale core scale permeability using a flow based scale averaging (FBSA) methodology to provide a more robust estimate of the absolute value of reservoir permeability. The impedance volume has also identified a number of sweet spots which will be tested with future appraisal drilling.