SEDIMENTOLOGY AND RESERVOIR CHARACTERIZATION OF THE SIGABOY FORMATION, DAVAO ORIENTAL, PHILIPPINES 

Karlo Lagera Queaño and Joseph Lambiase
Universiti Brunei Darussalam

ABSTRACT

        The Sigaboy Formation exposed on the Pujada Peninsula, Davao Oriental, Philippines consists of conglomerate-sandstone-mudstone units whose possible equivalent in the Agusan-Davao Basin is being targetted as a potential reservoir rock. These rock units represent submarine channelized and unchannelized deposits. The deposits are derived from an ophiolite suite, associated sediment carapace and metamorphic rocks outcropping on the Mati-Pujada Peninsula, Davao Oriental. The formation of these deposits also appears to be associated with volcanism based on the tuffaceous character of some of the deposits, the consistent abundance of plagioclase, and the presence of volcanic glass in some of the outcrops.

        Field and petrographic studies indicate that the Sigaboy Formation is not a promising petroleum reservoir. Porosity studies of the different facies from various stratigraphic intervals clearly show that porosity is very low. This is due to the unstable mineralogy, diagenesis, poor sorting and the unfavorable geologic setting of the Sigaboy Formation.