Publications

Sisi-Nubi field is located offshore Mahakam delta. Oriented in the NNE-SSW direction, this field consists of two distinct gas fields, Sisi in the north and Nubi in the south. A previously run deterministic inversion has assisted in the reservoir characterisation of this field to a certain extent. However, it lacked the resolution required to map thin sand channels and mouth bars. Besides that, assessment of uncertainties of the inverted elastic properties was not possible with deterministic inversion. To overcome these limitations, a geostatistical inversion was used to integrate various data at a higher frequency while allowing assessment of uncertainties. This inversion was performed in a detailed stratigraphic grid framework. An SGS scheme was used to invert for multiple P and S-Impedances which are all consistent with the available partial angle stacks, well data and the seismic velocity field. A preconditioning workflow was previously applied to the seismic angle stacks to compensate for amplitude attenuation caused by shallow bodies. Well based feasibility analysis showed prominence of segregation of sand, gas sand, carbonate and shale facies in the Ip and PR space. Multiple Ip and PR cubes were classified for volumetric analysis and lithofacies characterisation and its associated uncertainty quantification. Comparison of geostatistical inversion results with a previously run deterministic inversion shows that geostatistical inversion has better results in term of resolution compared to previous deterministic inversion.