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The Hypothetical Cretaceous Petroleum System of Trinidad and Tobago

Adrian Thomas
Petroleum Geologist, Prospect Generation, National Oil Company of Trinidad and Tobago, Petrotrin

Abstract

With the successes of the Early-Late Cretaceous deep water fan play offshore Western Africa and Eastern South America, growing attention has been paid to the possible extension of this play across the entire conjugate Atlantic margins. Due to the potential of this play type onshore Trinidad and Tobago, four deep wells were critically assessed to construct four petroleum system models which were used to assess the thermal evolution of the sedimentary section onshore Trinidad and Tobago with a focus on understanding the underdeveloped Cretaceous play. This study delineates the components of the currently sub-commercial Gautier/Naparima Hill-Gautier(.) (onshore Southern Basin) and the Gautier/Naparima Hill-Naparima Hill (.) (offshore eastern Trinidad) petroleum systems. Sub-commercial amounts of light oil were produced in various wells in Guayaguayare area, along the crest of the Southern Range anticline in wells drilled in the 1950's. There were also shows of relatively light oils in wells which were drilled in the western part of the Southern Basin onshore in the 1950’s. Within recent years, gas and condensates were tested from wells in the offshore extension of the Central Range Transpressive belt within Cretaceous reservoirs. These reservoirs consisted of the Gautier turbidites and fractured Naparima Hill argillite. The major components and processes of the system have also been assessed, in particular the timing of source rock maturation and the generation of possible fluid migration pathways. The accuracy of the four models was then tested by comparing them with published vitrinite reflectance plots and present day geothermal gradients. The ultimate goal of this study is to focus on the geodynamic evolution of the greater Trinidad region and to use these results to calculate maturity levels and petroleum generation stages within the Cretaceous Petroleum System. This work could serve to highlight the underexplored potentially prolific Cretaceous Petroleum System of Trinidad and Tobago.

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