Hydrocarbon potential of the mesozoic carbonates of the Bahamas

Abstract

In the early 1980's, the Getty Oil Company developed petroleum play concepts for several lease areas that it controlled in the Bahamas. Interest in these areas was based upon the facts that both Cuba and Florida had producing oil fields, oil shows were reported in test wells that had been drilled in the Bahamas and the well logs from these test wells indicated that the amount of evaporites in the Bahamas Platform carbonate-evaporite complex increased with depth. Evaporites indicate arid and often anoxic and reducing depositional environments which is favorable to the preservation of organic material.The Getty frontier exploration team addressed the formation and occurrence of source rocks, the thermal maturation histories of the potential source rocks, the presence of reservoir quality rock and possible migration pathways. The southern Bahamas was identified as the area that probably had the greatest amount of mature source rock. Thermal maturation (Lopatin) profiles for the Cay Sal well indicated that the Jurassic and Lower Cretaceous were within the oil generation window and the Upper Cretaceous was inunature. Thermal maturation (Lopatin) profiles for the Long Island well indicated that the Lower Jurassic was in the gas generation window, the Upper Jurassic and Lower Cretaceous were within the oil generation window and the Upper Cretaceous was inunature. Thermal maturation (Lopatin) profiles for the Great Isaac well indicated that the Jurassic and Lower Cretaceous were within the early oil generation window and the Upper Cretaceous was immature. Dolostone, with estimated porosities ofbetween 10% and 18% were thought to be likely reservoirs. Secondary reservoir objectives were skeletal, oolitic and reefal limestones. Evaporites, mainly in the form of anhydrites, and nonporous carbonates were identified as probable seals.Successful deep wells in the Gulf of Mexico are targeting subsalt structures at depths greater than 20,000 feet (6,100 m) (McMoran Exploration Co., 2009). The presence of significant hydrocarbons and reservoir quality rock at these depths, coupled with advances in seismic imaging, has opened up the possibility of the existence of other successful deep plays in frontier areas, such as the Bahamas.

Modeling the effects of diagenesis on carbonate clumped-isotope values in deep- and shallow-water settings

“…We use 30 °C/km for simplicity. We note that this geotherm is higher than the range given in Winkelstern and Lohmann (2016) of 13-18 °C/km for the area, which is based on unpublished geothermal measurements from the Getty Corporation (Epstein and Clark, 2009). We prefer the ODP-based geothermal gradients as the data and methodology used to calculate them are traceable and were conducted during drilling with the explicit purpose of measuring geothermal gradients (Pribnow et al, 2000).…”

Geophysical evidence for Mesozoic syn-rift salt diapirism in Southeast Bahamas

“…Principal geological reference for this study is a paper by Epstein and Clark (2009) who presented findings of the Getty Frontier Exploration team in the southeastern Bahamas in the 1980s. The paper describes in some detail stratigraphic information revealed in the six Bahamas wells.…”

The Protracted Evolution of a Plate Boundary: Eastern Cuba Block and Old Bahamas Channel

“…Early Jurassic rifting caused marine water influx, creating shallow water conditions (Epstein & Clark, 2009; Iturralde‐Vinent et al., 2016; Ladd & Sheridan, 1987; Moretti et al., 2003; Walles, 1993). Middle Jurassic syn‐rift redbeds were succeeded by evaporites in hypersaline lagoons (Figure 2b; Gaumet et al., 2004; Padilla y Sánchez, 2016).…”