Petroleum Prospects of the Mid Tertiary Reservoirs in the Southwest Peninsula of Trinidad
KPA Group of Companies
Geo-tectonically the Southwest Peninsula (SWP) of Trinidad lies within the Southern Basin which is a piggy-back basin filled with Pliocene to Pleistocene sediments. The Southern Basin extends eastwards onshore southern Trinidad and westwards into the southern Gulf of Paria. Throughout its extent it is underlain by the Naparima Nariva Fold and Thrust Belt (FTB) which extends further to the south and east onshore (to the Southern Range Anticline) and also offshore the East Coast (to the north and east).
In the onshore, while the younger Plio-Pleistocene reservoirs have yielded the bulk of the oil produced to date (over 1.5 billion barrels), turbidite sand members of the Cipero formation (Karamat, Herrera and Retrench) are also significant producers of oil and more recently gas. Some 200 million barrels of oil have been produced to date from these reservoirs onshore, current production being over 3,000 bpd of liquids and 70 MMCFGD.
With the exception of the SWP, the Southern Basin has been at least moderately explored. Deeper exploration, to the middle Tertiary has however been incomplete (and restricted to areas east of the Los Bajos Fault) because of the complexity of the over-thrusting within the FTB and the difficulty of identifying the structures within the FTB. Within the SWP itself, exploration of any kind has been sparse, with only around thirty wells having been drilled to date. Even more significant there has been only one single penetration into Upper Miocene Lengua age reservoirs and no well has yet penetrated the Middle Miocene Cipero age reservoirs which are known to exist and to be hydrocarbon bearing, further to the west in the southern Gulf of Paria and in Eastern Venezuela.
Geochemical work conducted on produced oils from within and areas adjacent to the SWP and from oils extracted from oil saturated Herrera sands ejected from the mud volcanoes in the area, have confirmed the presence of viable petroleum system with Herrera sands as the reservoir and Upper Cretaceous rocks as the source. In addition data from wells and from seismic, including a relatively new 3D seismic data set have identified the presence a highly prospective trend within the SWP in general and one large structure in the Cedros area onshore.
This poster will depict the geo-tectonic history and the petroleum system we have identified. It will then outline the play and prospect we have identified. Finally, it will illustrate two tools that we plan to use to upgrade our knowledge of the known prospect, and to identify other prospects within the play trend, namely full tensor airborne gravity (FTG) and surface geochemistry.
AAPG Search and Discovery Article #90203 © AAPG Geoscience Technology Workshop, Trinidad and Tobago Deep Horizon and Deep Water Frontier Exploration in Latin America and the Caribbean, March 9-11, 2014, Port of Spain, Trinidad