EXPLORATION POTENTIAL OF TRINIDAD-AND-TOBAGO

The Maturin Basin of eastern Venezuela, including Trinidad, has produced approximately 9.5 billion brls of oil, and is the site of significant new discoveries at E1 Furrial and E1 Carito. The present structural basin was formed by oblique compression during Oligocene to Miocene time, with the northern flank being a folded and thrusted terrane over-riding the South American continental margin. This deformed northern flank extends into the subsurface to the basin axis, and includes the southern half of the onshore and offshore territory of the Republic of Trinidad and Tobago. The basin was infilled from west to east by deep-marine shales, turbidites, pelagic oozes and deltaic sediments of Neogene age. Deltaic sands form the reservoirs of all the important oilfields in the basin. Oil occurrence on the northern flank of the basin is associated with thrust-related structures in Venezuela and wrench-related structures in Trinidad. There are many excellent prospects along the flanks of wrench-related ridges with diapiric cores in the Trinidad and Tobago portion of the basin. Late Pliocene and Pleistocene deltaic sands shale-out northwards in very thick aggradational lobes, enhancing the prospectivity of the southern flanks of these ridges. The prospectivity of the fold-and-thrust belt in Trinidad and Tobago is limited by the distribution of reservoir facies in pre-Pliocene sediments. Candidates for non-deltaic reservoirs are Miocene limestones, Oligocene sheet-sands, Eocene turbidites and Cretaceous fractured argillites.