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Hydrocarbon Potential of the Nicaragua Rise Based from Reevaluation of Vintage Seismic and Well Data from the 1970s and 1980s

Emmet, Peter A.1; Mann, Paul 2
1 Brazos Valley GeoServices, Inc, Cypress, TX.
2 Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX.

The 270,000 km2 area of the Nicaragua Rise (NR) offshore Honduras and Nicaragua (defined by 2,000 m isobath) remains underexplored from 33 exploration wells drilled from 1970-80 with numerous oil and gas shows but no commercial production. Assessment of offshore prospectivity is limited; only 2 exploration wells on NR have been drilled in water depths > 100 m. Synthesis of 13 wells and 6,200 km of 2D seismic (1970-80) in Honduran waters and construction of regional structure and isopach maps clarify the evolution of this modern carbonate bank with deep-water reentrants. U. Jurassic syn-rift clastics are overlain by U. Cretaceous carbonates. Regional N-S shortening in the Cenomanian led to the demise of the carbonate platform with accumulation of organic-rich carbonates and gypsum in restricted basins. An U. Cretaceous basal chert-bearing conglomerate is overlain by fine-grained redbeds of U. Cretaceous age. An angular unconformity separates deformed Mesozoic strata from overlying Tertiary clastic and carbonate rocks. Eocene strata locally present above the unconformity are clastic on the northern flank of NR and carbonate on the southern flank. An Oligocene section is thin or absent but Miocene and Pliocene strata are locally very thick and predominately clastic. The northern flank of NR (Tela basin) is a continental borderland across which Miocene turbidites and Eocene (?) and Cretaceous strata drape over deep-seated basement structures, and numerous deep (> 4000 m) subbasins remain unexplored with modern seismic or drilling. Drilling in 1973 documented an active hydrocarbon system comprising rich M. Eocene source rocks and fractured M. Eocene carbonate reservoir rocks in the Mosquitia basin which straddles the crest of the east-plunging NR. North-trending grabens that cross NR may bury M. Eocene strata sufficiently to have charged commercial oil accumulations. The top Cretaceous marker is a broadly-arched angular unconformity below which is a thrust-fold belt comprised of U. Cretaceous strata. An active oil-prone Cretaceous hydrocarbon system is suspected, and the presence onshore of coal-bearing clastics of U. Jurassic age suggests that a pre-Cretaceous gas-prone hydrocarbon system is possible.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009