Tectono-Stratigraphic Habitat of Hydrocarbons in The Deep-Water Frontier Provinces of Trinidad and Tobago

Abstract

Abstract The Trinidad and Tobago deepwater provinces form a structurally complex, frontier basin adjacent to the prolific and well-studied Columbus Basin shelf province that contains over 25 trillion cubic feet (tcf) of gas reserves and has produced over 1 billion barrels (bbls) of oil. The deep horizons in the deep-water area east of Trinidad remain largely underexplored with eight exploration wells to date. We evaluate elements of the petroleum system for the Trinidad and Tobago deepwater area in the context of the tectono-stratigraphic evolution. We use ~10,000 km of 2D seismic reflection lines which are recorded to depths >12 seconds TWT and well data to interpret the distribution and continuity of tectono-stratigraphic sequences and to identify and constrain the activity of key structural features. We examine the relationships among the tectonic configuration and crustal structures formed along the southeastern margin of the Caribbean – South American (SA) plate boundary zone, the location and timing of depositional systems and sedimentary pathways. The Trinidad and Tobago deep-water area is located within the ~200-km-long transition zone from westward directed subduction to an east-west oriented strike-slip margin, and it covers an area which includes the transition from the slope province of the foreland Columbus Basin to the southern termination of the Barbados accretionary prism (BAP). Thick Cretaceous strata document the relatively quiescent conditions which existed in the eastern offshore Trinidad area prior to deformation associated with the arrival of the Caribbean plate. The transition to active subduction and collision by the Mid-Miocene is recorded by; (1) basement flexure, (2) segmentation of the broad, relatively quiescent Cretaceous margin into smaller confined foreland and piggy-back basins and, (3) the formation of the BAP composed of thrust blocks of deformed Paleogene to recent sediments which are detached above less deformed Cretaceous sedimentary succession and oceanic basement. We show how the deformation associated with the transitional tectonic zone in which the Trinidad deep-water area is situated influence the respective elements of the petroleum system. Consequently the deepwater petroleum system differs from the petroleum provinces to the west of the COB and differences are also noted across the sub-provinces within the deepwater area.