Optimizing the Use of Structure-Guided 3D CSEM Inversion to Characterize Fractured/Karsted Carbonates in Offshore North-West Borneo

Fractured and/or karsted carbonates (FKC) are commonly associated with reservoir effectiveness and is useful in the study for carbon dioxide storage sites. We have performed a 3D seismic guided CSEM inversion to map boundaries of carbonate and identify fractures and karstification of carbonates. The resistivity results matched the resistivity well log from a nearby well satisfactorily, providing geological justification to interpret the presence of karst features in the resistivity volumes. Lateral boundary of the carbonate prospects was mapped based on resistivity characteristic. Resistivity slices of the models clearly demonstrated that the areal distribution of low and high resistive zones can be mapped and useful deductions such as the presence of fractures and karsts. From this study we have demonstrated the usefulness of integrating seismic and CSEM quantitatively for FKC mapping which helps understand porosity better in carbonates contributing positively to carbon dioxide storage studies.