Print this pageA Viable Exploration Play in Deepwater Trinidad with Fans, Structures, and Favorable Basin Models
A re-interpretation of the eastern deep to ultra-deep water area of offshore Trinidad results in a viable exploration opportunity. The study was a joint project sponsored by the Ministry of Energy and Energy Industries of Trinidad and Tobago and by ION/GXT, and utilized mega-regional, long offset PSDM/PSTM lines designed to image deep structure and stratigraphy. This work demonstrates that it is premature to conclude that the unsuccessful drilling campaign in the first deepwater Blocks 23-27 tested the petroleum system of the eastern Trinidad deepwater area. Modern sequence stratigraphy interpretation shows a sheet-form, basin floor fan play further to the east and north of these blocks. A robust Miocene to Pleistocene sedimentation derived from the Orinoco River system developed broad outer-neritic to mid-slope wedges of confined sands that extended far into the deepwater areas and this is the drilled facies. A key analog for this view is offshore Nigeria where upper to mid-slope confined sand facies have yielded marginal to unsuccessful wells and the best discoveries and sands have been encountered in the lower slope to basin floor fans. Complex mobile shale features in the Trinidad deep water area are the product of two major systems that form intersecting trends of structural belts, deforming on a common Lower Tertiary detachment surface. The first major structural system formed as gravity forces acted on sediment-loading coming from the robust Orinoco drainage system to the southwest. Gravity sliding and translation along the Lower Tertiary detachment form a linked extensional/contractional system moving to the east-northeast. This contractional toe collides with a second major system due to compressional forces from the eastward motion of the Caribbean Plate, and creates the complex, compressive structural pattern we see today, but one with many large lead opportunities for exploration; leads that span a range of sizes, depths, and ages. A foredeep is developed in front of the advancing Caribbean Plate which depressed the Cretaceous beneath the area of previous deepwater drilling. Basin modeling on key seismic lines demonstrates an area of oil potential as the Cretaceous source rock rises again toward the east and northeast. Here the timing of the maturity of the source rock overlaps the timing of the reservoirs, seals, and structures, and predicted pressures indicate that deeper targets in the Miocene to Oligocene are favorable for seals.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil