Hydrocarbon Potential of the Northeastern Caribbean Based on Integration of Depth to Basement and Source Rock Maturity Data

Abstract

The northeastern Caribbean on the islands of Hispaniola and Puerto Rico and their offshore areas has over one century of hydrocarbon exploration with over 72 wildcat wells drilled, but insignificant commercial production to date. A key question is whether these large Caribbean oceanic islands, removed from the input of large terrigenous river systems found in other areas like the Gulf of Mexico and northern South America, have experienced sufficient subsidence and depth of burial for any source rocks that may be present to reach maturity and produce commercial hydrocarbons. We compiled well data and seismic interpretations from previous workers into a depth to Cretaceous-Eocene igneous-metamorphic basement map for Hispaniola, Puerto Rico, and their offshore areas. These maps show the areas of greatest depth to igneous-metamorphic basement and overlying fill to include the Enriquillo basin of the Dominican Republic (5 km), San Juan basin of the Dominican Republic (5.3 km) and Central Plateau basin of Haiti (5.3 km), Cibao basin of the Dominican Republic (5 km), north coast basin of Puerto Rico (1.7 km), south coast basin of Puerto Rico (1.3 km), and Virgin Islands basin (8 km). Of these seven basins, 2D basin modeling using available vitrinite data show that only the collinear San Juan and Azua basins of the Dominican Republic have achieved sufficient burial to place known and inferred source rocks into the oil window in both areas. This result is supported in the case of the Azua basin by the presence of natural, surficial oil seeps and limited production from shallow wells (about 50,000 barrels of 20° API, biodegraded oil was produced in the 1940s and 50s). Low Ro% values of sediments in the Enriquillo basin of comparable thickness and identical source rocks to the San Juan and Azua indicate lower heat flow in the Enriquillo basin. Some of the lack of commercial success in the San Juan basin and adjacent Central Plateau basin of Haiti may reflect that only a total of four wildcat wells have been drilled, two of which had oil and gas shows. Biogenic gas is likely more prevalent in these same basins and within the larger deltas of Hispaniola.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015