New constraints on the tectonosedimentary evolution of the offshore San Pedro Basin (southeastern Dominican Republic): implications for its hydrocarbon potential

Abstract

AbstractThe San Pedro Basin (SPB) is located at the southeastern margin of Hispaniola Island (Dominican Republic and Haiti). It is the largest offshore basin of the Dominican Republic with an extension of 6000 km2. The basin has a maximum water depth of 1600 m and is positioned to the rear of the Muertos Thrust Belt (MTB). The SPB is bounded to the west by the Azua Basin which has a proven petroleum system and small oil production has been recovered from the Maleno and Higuerito fields. While in the scientific literature the SPB and the Azua basins have been considered as disconnected sedimentary systems, our current study suggests both that shared a common tectonic evolution and therefore the presence of an untested petroleum system in the SPB can be expected. We have carried out a detailed review and synthesis of the onshore systematic geological mapping (the SYSMIN I and II programmes) together with the integration of a large volume of subsurface geophysical data. This includes analysis of 60 exploration wells provided by Banco Nacional de Datos de Hidrocarburos (BNDH) of the Dominican Republic, processing of new 2D multi-channel seismic data from the Spanish Research Project NORCARIBE, reprocessing of legacy seismic profiles, and interpretation of gravity and magnetic data. Our results have led us to propose a new evolution model for the SPB. The basement of both basins consists of Cretaceous sedimentary and volcanic rocks of intra- and back-arc settings. A change in the stress regime in the Campanian led to partial inversion of the basement units favouring the deposition of two main sequences of Campanian–Maastrichtian and Paleocene?–Eocene age in a submarine foreland setting. Due to collision between the Carbonate Bahamas Province and Hispaniola in the middle Eocene, compressional stresses were transferred to the south where Cretaceous and Paleogene sediments were deformed, forming the current configuration of the MTB and generating a new accommodation space where the SPB has developed since upper Eocene–Oligocene until Present. While the Azua Basin was finally exhumed after the Miocene–Pliocene, most of the SPB continued as an actively subsiding basin. This new model has allowed identification of the main elements of the petroleum system in the SPB: a mature Upper Cretaceous source rock; and Oligocene–Miocene carbonate and clastic reservoirs interbedded with sealing shales and marls. Main traps (structural and stratigraphic) are of Oligocene–Miocene age and their formation seems to be synchronous to oil generation. While the main elements of the petroleum system seem to be present in the basin, timing is a key issue that must be addressed and assessed in any future exploration in the basin.