NOTES ON THE GEOLOGY AND HYDROCARBON POTENTIAL OF THE SIBUTU BLOCK, SOUTHERN PHILIPPINES

Nelson D. Trinidad & Raymond T. Barcelona

       A complex of deep sedimentary troughs separated by shallow narrow volcanic ridges best describes the northern half of the Sibutu Block while its southern half follows the structural grain of the Tarakan Basin to the south where deltaic deposits predominate. In the context of regional geology, the Sibutu area is interpreted to be a submerged ridge that forms the southern boundary of the greater Sulu Sea Basin and the northern limit of the Tarakan Basin.

        The 1995 evaluation study of the Sibutu Block using then available seismic data had identified as many as twenty-three (23) structural leads. A good number of these leads were mapped as drape features over interpreted old basement highs while some have developed as fault-related anticlinal features within the interpreted carbonates (Blue Horizon) corresponding to the Top of the Early Miocene.

        A more recent re-evaluation of the Sibutu area that utilized much-improved reprocessed seismic database brought to fore a clearer picture of the major structural elements and how could these possibly evolved. Reinterpretation of the same key horizons resulted in the downgrading of some of the original leads while new ones have been identified. Additional studies including a proposed aerogravity/magnetic survey are being programmed to firm up these leads into exploration prospects.