Abstract

Known hydrocarbon occurrences are indicative of a widespread and active, offshore petroleum system of the Nicaraguan Rise (western Caribbean Sea). We identify key petroleum system elements and processes using geological, geophysical, and geochemical data integrated into a three-dimensional petroleum system model that includes an early and late Eocene / Oligo–Miocene (!) petroleum system. Early and late Eocene source rocks identified on the Nicaraguan Rise include clayey, calcareous limestone and pelagic shale containing kerogen type II and III with TOC values ranging from 0.85% to 3.74%. Potential reservoirs include transitional to deep marine environments with clastic pinch-outs, dolomitized shallow marine carbonate complexes, and reefal buildups. Potential seal rocks include gray calcareous shale, siltstone, and silty shale deposited above regional and local unconformities and as intercalations within carbonate formations. The complex tectonic history of the area has produced known structural and stratigraphic traps effective for hydrocarbon accumulation with recovered hydrocarbons ranging from 21° API to 45° API. Thermal history modeling based on paleo-heat flows, burial histories, and transformation ratio maps shows that the initiation of hydrocarbon generation began during the early Oligocene (35 Ma) at 69 mW/m² with an average hydrocarbon expulsion of 7.15 MMBOE per km² from Eocene source rock intervals. Our proposed model predicts vertical migration on the Nicaraguan Rise with a predicted generation-accumulation efficiency of 3.5%.