Onshore Exploration Drilling Success in Southern Basin Trinidad
From 1857 to present, some 13000 oil wells have been drilled onshore Southern Basin of Trinidad producing in excess of 1.5 billion barrels of oil todate, primarily from Late Miocene to Pleistocene deltaic sandstones. Just under 2000 of those wells drilled and tested Middle Miocene deepwater turbidites, with less than a hundred testing Cretaceous reservoirs. With scores of old, abandoned and to some extent stratigraphically mature fields scattered along its length and breadth, and the ever increasing rate of decline of the country's oil production, the basin required a new wave of exploration, to stratigraphically older and deeper reservoirs. In 2013, the Ministry of Energy launched an Onshore Bid Round, the first in just 15 years Three blocks adjacent to established oilfields with production primarily from Middle Miocene Herrera deepwater turbidite sandstones, were marketed and 11 bids were received. The Rio Claro Block was awarded to Lease Operators Limited, the St. Mary's Block was awarded to Range Resources and the Ortoire Block was awarded to Touchstone Exploration. Each block entailed minimum work obligations of 4 exploration wells each to targets of at least 5000ft. In 2019, the exploration drilling campaign kicked off for both Lease Operators Limited and Touchstone Exploration. LOL drilled their Ah Yah Yie well to a TD of 6150ft encountering stratigraphy as old as Early Miocene. Unfortunately, the well failed to encounter effective reservoirs and was plugged and abandoned. LOL's second well, Barakat was drilled in vicinity of the Balata East field, where it encountered oil bearing Herrera sandstones in structures on trend with the Balata East thrust sheet. This well has thus proven that the current oilfield can be extended with careful outstep drilling into tear fault bound thrust sheets to the west and south west. Touchstone Exploration drilled their Coho well testing a SW plunging anticline immediate south of the Penal Barrackpore anticlinal trend, in the Tableland area and successfully discovered gas and condensate in Herrera sands within two thrust sheets. Touchstone's Cascadura well was then drilled testing a structure on trend with Penal Barrackpore anticline immediately south of the town of Rio Claro. The well encountered three Herrera thrust sheets as prognosed with oil bearing sandstones at two structural levels. The lowermost of these sandstones appear to be near vertical to overturned and correlates well with the Overturned Limb or Intermediate Herrera from Penal Barrackpore. A string of successful drilling, supported by extensive structural modelling, has breathe new life back into Southern Basin, de-risking adjacent prospects and opening up more opportunities for exploration investment. Adamant optimism, sound geological concepts and supportive policies are the fundamental principles to ensuring the rejuvenation of T&T's hundred-year-old industry.
AAPG Datapages/Search and Discovery Article #90361 © 2019 AAPG Latin America & Caribbean Region Geosciences Technology Workshop, Recent Discoveries and Exploration and Development Opportunities in the Guiana Basin, Paramaribo, Suriname, November 6-7, 2019