Seismic Facies Analysis of the Sandakan Sub-Basin, Sulu Sea, Philippines
Futalan, Krestabelle, M.
Geoscience Masters Degree, 2011
University of Adelaide
Seismic facies mapping involves association of seismic reflection attributes with the depositional sequences of a basin and provides a framework for correlating between seismic and well data. This thesis presents a gross seismic facies mapping analysis in the Sandakan sub-basin, located between the islands of Borneo and Sulu. The sequence of interest includes the Pliocene to Middle Miocene units of the Togopi, Ganduman and Sebahat Formations, which are known to host hydrocarbons in other parts of Malaysia. Data incorporated in this analysis includes 2D seismic, gamma-ray logs, biostratigraphy and cuttings description from four wells. Results of the mapping reveal that changes in the seismic facies correspond to evolution of the basin through time. The Sandakan sub-basin shifted from an actively prograding fluvio-deltaic system during the Late-Middle Miocene, into a shelfal marine environment during the Pliocene. However, lithofacies only subtly change with seismic facies type and appear to be more controlled by provenance. This mapping procedure has enabled a model of the basin’s depositional environments to be produced. The results of this investigation provide insights into further understanding the basin’s prospectivity; specifically the distribution of source, seal and reservoir rocks in the basin.