Geological Background
The Caribbean – South American plate boundary is a broad deformation zone that resulted from prolonged continuous interaction between the South American and Caribbean plates. These interactions resulted in the development of fold and thrust systems and foreland basins in different stages of development along a right lateral transpressional zone that extends ~1500 km from northern Colombia to Trinidad and Tobago. In northwestern SA (eastern Venezuela and Trinidad & Tobago) the deformation area is approximately 300 km wide.
The Tobago Basin is a curved-shaped forearc basin with a sedimentary fill of approximately 14 km that transitions from the Carupano Basin in offshore eastern Venezuela. The origin and age of the Tobago basin basement is unknown. However, radriometric and peleontologic ages from outcrops found in Tobago and basement ages from Oil & Gas exploration wells in the Carupano Basin seem to indicate a Late Cretaceous forearc origin.
The complex architecture of the southeastern Caribbean basins and the poor understanding of the characteristics and distribution of source and reservoir rocks make the hydrocarbon exploration challenging in this area. However the presence of oil and gas seeps, oil fields, and giant gas fields, makes the Southeastern Caribbean region an attractive target for current and future oil and gas exploration.
Caribbean Atlantic Margin Deep Imaging Seismic Survey
During 2018 and the first quarter of 2019, Geoex-MCG acquired the Caribbean Atlantic Margin Deep Imaging seismic survey (CAMDI). This survey consists of 16,433 km MC2D long offset seismic data (Figure 1). This transnational survey covers acreage across the maritime borders of Barbados, Trinidad & Tobago, Grenada and St. Vincent. Gravity and magnetic data were also recorded throughout the survey.
Approximately 3317 km of MC2D long offset seismic data of the CAMDI survey are located offshore Trinidad & Tobago (Figure 1). The survey grid offshore Trinidad & Tobago is designed to provide more details, enabling explorationists to outline potential prospects and tie the producing areas in Trinidad & Tobago to the underexplored deeper part of the Tobago Trough.
The seismic data was processed through a modern broadband workflow in which high quality Pre-stack Time and Pre-stack Depth products were generated. The applied processing sequence also intended to illuminate deeper geological formations up to and below the Basement.
Hydrocarbon Potential
Source Rock: DSDP wells on the Southern Caribbean Plate offshore Venezuela and an ODP well offshore Barbados have shown evidence of a regional Upper Cretaceous source rock equivalent to La Luna and Querecual Formations of Venezuela and Colombia, respectively. Maturation is predicted to have started during the Miocene in Eastern Venezuelan Basin and during the late Miocene-Recent offshore Trinidad. Onshore Barbados, oil and gas is produced from the Eocene Scotland Group sourced from a La Luna age equivalent source rock. This oil play remains unproven in the Tobago Basin as there are no well penetrations. However, the CAMDI MC2D deep imaging data reveals a distinctive regional high amplitude horizon that, based on its stratigraphic position could represent the Top Cretaceous (Figure 4). In the Tobago Trough a potential deep source rock is postulated to be in the Cretaceous Mejillones Complex.
Reservoirs and Traps: Structural trapping plays a major role within the Southeastern Caribbean. The plate tectonic evolution of the region suggests a deep marine sequence in which potential reservoir sands are turbidites. While most targets in nearby fields are in the Pliocene, the CAMDI MC2D seismic data indicates that Mid Miocene and Eocene sands (turbiditic deposit and channels) are also possible reservoirs (Figures 2 and 3). The high contrast between these sands and the sediments above them represent a seal for the system. Possible leads also include structural traps such as four- and three-way closures and Direct Hydrocarbon Indicators (DHI’s) can be observed in connection with many of these traps. (Figures 2 and 3).
Trinidad and Tobago Deep Water Competitive Bid Round
The Ministry of Energy and Energy Industries of Trinidad and Tobago is expected to offer Blocks in the Deep-Water acreage in H1 2021. More information about the Bid Round can be found at https://www.energy.gov.tt/2020-deep-water-competitive-bid-round.
All the necessary hydrocarbon elements for a working petroleum system are present in the region. Gas production and recent discoveries from nearby fields offshore Trinidad, along with the onshore Barbados oil field production provide evidence for commercial hydrocarbon potential in the region. The CAMDI MC2D seismic data set shows a regional distribution of leads, including multiple structural traps and turbidite reservoirs with the potential to be of very high quality. Overlying hemipelagic marine clays would form the sealing facies, with migration to the reservoirs occurring along thrust faults associated with the deformation front. The presence of a La Luna age equivalent source rock suggest an oil play potential within the Tobago Trough.