Petroleum Potential of Onland Basins in Hispaniola (Dominican Republic and Haiti) Based on Integration of Vintage Well and Seismic Reflection Data with Geochemical Data

Osmond, Johnathon; Mann, Paul; Pierce, Stephen

GPS studies of Hispaniola show that maximum oblique plate convergence is centered between the Caribbean and North America plates. The onset of oblique collision occurred in late Miocene time and is responsible for forming thrust-bound ramp basins. To characterize hydrocarbon systems in south-central Hispaniola, we assess five Neogene stratigraphic units for petroleum generation potential and likelihood of petroleum retention by structural traps. Natural oil seeps and small-production oilfields in the region confirm the presence of working hydrocarbon systems, but previous work does not characterize the systems nor constrain their scale or capacity. Poor TOC values are associated with most Cretaceous to Neogene rocks in the Dominican Republic, however, middle Miocene Sombrerito Formation rocks show marginal petroleum generative potential. Reservoir rocks for the Maleno and Higuerito oilfields are the late Miocene submarine fan-deposited Trinchera sandstone and reefal facies of the Sombrerito limestone. Aeromagnetic data suggests a belt of Plio-Pleistocene volcanic rocks to the west with shallow intrusives beneath the two oilfields may have facilitated oil maturation. We suggest the possibility that thrusting of sabkha like organic rich facies of the Sombrerito limestone may also have played a role. The high sulfur contents, C-13 abundances, and pristine phytane ratio of the oilfield samples suggest an origin of mixed terrestrial and algal materials in a restricted carbonate marine environment. Seals are likely to be the shaly interbeds in this submarine fan sequence. Seismic data suggest structural traps linked to the Maleno and Higuerito oilfields are a large east-west anticline and thrust folds associated with the post-late Miocene formed Los Pozoz Fault. The steeper limbs of these anticlines reflect southwestward overthrusting of the Cordillera Central block over the Azua basin. Seeps at Higuerito indicate that faulting has compromised the structural trap. Late Cretaceous Hatillo limestone from eastern Hispaniola, Ocoa Bay beach tar, and DSDP samples from the Caribbean Sea have smaller C-13 abundances than the Higuerito and Maleno oils, indicating the Ocoa Bay and Hatillo source rocks have a different origin. Areas of western Azua basin and Enriquillo basin infer an open ocean pelagic setting while outcrop observations and oil geochemistry indicate a Sombrerito source deposited in a shallow, highly restricted marine environment.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013