Abstract

The 2009 discovery of the 17 tcf, thermogenic, Perla giant gas field in the Gulf of Venezuela (GOV)—which is hosted in a 240 m (787 ft) thick red algal carbonate reservoir of late Oligocene–early Miocene age—stimulated a more regional re-evaluation of potentially large, Cenozoic carbonate reservoirs along the continental margins and accreted Caribbean arc terrane of northwestern South America. This chapter focuses on describing the petroleum potential of early Miocene carbonate reservoirs of the La Vela Basin (LVB) of offshore, western Venezuela that is located 100 km (60 mi) east of the La Perla gas giant. Our subsurface data for the LVB—which was kindly provided by the Venezuelan National Oil Company (Petroleos de Venezuela, S.A., or PDVSA)—include a basinal-scale database of 1100 km² (680 mi²) of 3-D seismic data that are tied to 52 wells. We use these data to assess 143 m (470 ft) thick, coralline, carbonate reservoirs of the LVB of early Miocene age that have produced minor amounts of oil and gas since the 1970s. Additional oil and gas producing reservoirs of the LVB include fractured and metamorphosed basements of Neoproterozoic, Permian, and Cretaceous age that are exposed on the adjacent Paraguana Peninsula and have been previously sampled and radiometrically dated from both outcrops and cores of wells drilled into basement of the LVB. We integrate gravity and magnetic data to map the three types of crystalline basement that underlie the LVB. We use the seismic well data to define orientations and types of faults, thickness variations, and sedimentary facies of the main carbonate reservoirs unit (early Miocene Cauderalito Member of the Agua Clara Formation). We compare the characteristics of the coralline La Vela carbonate reservoirs with known late Oligocene–early Miocene, red algal, carbonate ramp settings of the Gulf of Venzuela (Perla gas giant) and the early Miocene, San Luis red algal ramp of the onshore, Falcon Basin (FB). The most prospective carbonate reservoirs are red algae-based and are related to their distinctive ecological and tectonic settings.