Cuba's Oil and Gas Potential in the Greater Antilles-Caribbean

Introduction:?

In the Caribbean Sea, within the Greater Antilles, Cuba becomes a surprising contender in hydrocarbon development with a robust state energy sector support. The island measures 109,884 km2 (42,426 sq. mi), Cuba ranking as the second most populous Caribbean nation, with nearly 11 million inhabitants.

Business and Political Framework:?

In August 1960, under President Osvaldo Torrado and Prime Minister Fidel Castro's leadership, Cuba nationalized American-owned refineries, sugar factories, and mines, totaling $1.7 billion in U.S. oil assets.

Renowned for its Cuban cigars, Cuba's journey in hydrocarbon development has been marked by interruptions, primarily due to the U.S. embargo imposed in October 1960. Cuba's involvement in oil and gas exploration dates back to the 1860s when it first discovered heavy crude oil. The Motembo oil field in 1881 yielded light crude oil, and the 1950s witnessed a boom following the discovery of the Jatibonico field in the central basin, involving companies like Grupo Jarueca, Atlantic Refining, Gulf Oil, Shell Standard Oil, and Union Oil.

The 1990s saw heightened interest, with Alturas, British Borneo, Geopetrol, Premier, and Sherritt signing agreements for offshore blocks. These blocks were given to CNPC, Petronas, PetroVietnam, PDVSA, ONGC, Repsol, Sonangol, and Zarubezhneft.

Geological History of the Provinces:

?Cuba possesses two distinct petroleum provinces, with the Northern Province being the primary source of hydrocarbons. The Northern Province is associated with a folded and thrust belt, while the Southern Province features tertiary basins overlaying volcanic rocks and ophiolites, thrusting over the North American paleomargin.

Most known oil field developments within the northern petroleum province are established oil and gas plays existing in isolated wells, water sources, and surface areas across the country. The detailed records, geographical boundaries, and stratigraphic extensions of the petroleum systems in the Northern Petroleum Province have defined four stratigraphic intervals of source rocks (Callovian Middle Jurassic, Oxfordian Upper Jurassic, Tithonian Upper Jurassic-Barremian Lower Cretaceous, and Aptian Lower Cretaceous-Turonian Upper Cretaceous) and three oil genetic families (I, II, and III). Families I and II resulted from the same source rock level (Tithonian Upper Jurassic–Barremian Lower Cretaceous), and Family III originated from Aptian Lower Cretaceous-Turonian Upper Cretaceous source rocks.

In the Southern Province, though indicators suggest active source rocks, a lack of comprehensive knowledge impedes the definition of petroleum systems. Biomarker data indicates that in the southern basins of Cuba, the petroleum systems identified in the Northern Province can coexist with others. These systems are associated with Upper Cretaceous or Tertiary source rocks, as evidenced by Oleanano's presence in the oil from the Ana Maria-1 well and the sand of the Guacanayabo Gulf Keys.

Geochemical Background of Source Rocks:

Research on the geochemistry of source rocks and crude oil in Cuba has been limited and challenging to access. Efforts to expand this database involved collecting new samples, including outcrops, source rocks, oils, and gases, in the Northwest region.

These samples, particularly from the Jurassic section in Western Cuba, were extracted during the syn-rift stage, encompassing syn-rift, post-rift, and Cretaceous Bahamas channel deposits. Crude oils in this region exhibit a wide range of characteristics, from very light, mature, low sulfur crudes to high sulfur, NSO-rich, biodegraded heavy oils, occasionally featuring remigrated hydrocarbons, especially in central Cuba.

The previous studies on the geochemistry of hydrocarbons in the northern carbonate reservoirs emphasized the Upper Jurassic and Lower Cretaceous units to understand the encountered petroleum composition heterogeneity. For example, within a few kilometers along the Northern coast, equivalent age-producing levels have shown either good-quality oils (>20°API) or highly viscous oils (<15°API) enriched in sulfur, metals, and NSO compounds.

Source Rocks in Various Geological Ages:

• Middle Jurassic Source Rocks:?The San Cayetano Formation, deposited during the rift genesis phase, is characterized by alternating sandstones, shales, and clays.

• Oxfordian Upper Jurassic Source Rocks:?This period marked a transition from terrigenous to carbonate sedimentation due to the communication of primitive basins with the ocean. Marine components are evident in the kerogens (types II-III and II) during this time.

• Kimmeridgian Upper Jurassic-Barremian Lower Cretaceous Source Rocks:?Sediments during this age range include formations such as San Vicente, El Americano, Tumbadero, Tumbitas, Artemisa, Sumidero, Cifuentes, Ronda, Morena, Jaguitas, and Margarita. These sediments reflect a transgressive sequence, transitioning from shallow marine environments (Kimmeridgian) to deeper deposits (Tithonian-Barremian).

• Aptian Lower Cretaceous–Turonian Upper Cretaceous Source Rocks:?Sediments from this interval represent significant depths within the basin. Notably, continental contributions via turbidities are evident in identified Tectono-Stratigraphic Units (TSUs) in Cuba (Organos, Rosario, Placetas, and Camajuani). Consequently, these sediments display a mixture of marine organic matter (type II) and continental material (type III) originating from turbidite processes.

Future Plans:

In 2013, Meblana Energy, an ASX-listed company, became pre-qualified as an operator in Cuba and selected Block 9 on the north coast as a preferred prospect due to its alignment with the vast Varadero Field. In 2015, Melbana received the Block 9 Production Sharing Contract (PSC). Subsequently, Sonangol, Angola's state-owned oil company, initiated a two-well drilling program in 2020.

In 2021 and 2022, Melbana conducted drilling operations with the Alameda-1 and Zapato-1 wells. Alameda-1 has revealed three distinct reservoirs, each independently evaluated and estimated to hold an astonishing 5 billion barrels of oil, surpassing initial expectations. Zapato-1 encountered a thicker-than-anticipated volcanic sequence and was temporarily halted, with the possibility of resuming operations in the future.

Another major company from Australia, Petro Australis Energy Limited (PAE), has major upcoming projects in Cuba. PAE holds three onshore PSCs, two awarded in 2018 and the third in 2020. The main focus of activities is Block 21A-IOR (Incremental Oil Recovery), which entails the Pina oil field and the underlying and surrounding exploration of Block 21A-P. CUPET discovered Pina in 1989, and only half the field is exploited, with no new wells drilled since 2001. PAE is planning a series of production wells with a target of an initial ramp-up of 5,000 BODP.

These significant activities from various multinational companies with exploration expertise and experience can economically simulate the cash inflow into Cuba and, increase the potential for regional activity opportunities within the Caribbean and Gulf of Mexico regions.

References

Cross, I. (2023, August 25). Keeping an eye on the Cuban part of the GOM. Retrieved from GEOExPro: https://geoexpro.com/keeping-an-eye-on-the-cuban-part-of-the-gom/

C. Magnier, I. M. (2003). Geochemical characterization of source rocks, crude oils. In Marine and Petroleum Geology 21 (p. 196). Elsevier.

Manuel Enrique Pardo Echarte, O. R. (2019). Non-seismic and Non-conventional Exploration Methods for Oil and Gas in Cuba. Cham, Switzerland: Springer.