Print this pageThe Relationship Between Deepwater Deposition and from Active Accretionary Wedge, Ultra Deep Water Trinidad
Pablo N. Eisner1, Mo Etemadi1, Laszlo Benkovics1, Luis Anzulovich1, Dewi Jones1, and Jean Gerard2
1Repsol Exploration and Production, The Woodlands, TX
2Repsol Exploration, Madrid, Spain
The Trinidad Ultra-deepwater (UDW) area lies on today’s continental slope off the eastern coast of Trinidad; it overlies oceanic crust and is part the Barbados Fold Belt. Sedimentation has been rapid due to the constant feeding of clastic material from the Orinoco River. Deepwater turbidite sands are interbedded with shales, possibly providing both reservoir and seals. Deepwater channels and lobes have been identified and mapped in the existing 2D seismic. There are 13 wells that reached up to the lowest Pliocene, immediately to the west of the UDW area, providing a direct tie to the seismic stratigraphy interpretation. Priority for reservoir was given to the late Middle Miocene to Pliocene, if only because deeper sections are increasingly overpressured and therefore difficult and risky to drill. Clastic composition and texture are interpreted to be mature, with mainly quartzose sands of continental affinity, consisting of amalgamated sand in the lobes and fine sand/silt interbedded with silty shales, in predominantly distal turbidites or overbank deposits. Most of the structures identified were active during the Upper Miocene and Plio-Pleistocene, so no areas are expected to show sheet like, unconfined basin floor fans. The ongoing development of the accretionary wedge will have focused sediments in a NNE-direction, in contrast to the SW-NE basinal axis trends which would dominate slightly older sediments. The growth of mud diapirs, probably initiated in the Plio-Pleistocene as increased amount of sediments were deposited further complicated the depositional pattern. Turbidite deposition of Upper and Middle Miocene age is interpreted to be of distal fans facies, while in the Plio-Pleistocene, they respond more to a minibasin setting and channel-levee facies.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas