U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005–3009

February 2005 Printed on recycled paper

Using a 

geology-based

assessment 

methodology, the 

U.S. Geological Survey

estimated a mean of 

4.6 billion barrels of 

undiscovered oil, a 

mean of 9.8 trillion 

cubic feet of undiscovered natural gas 

(8.6 trillion cubic 

feet of associateddissolved gas and 

1.2 trillion cubic feet 

of non-associated 

gas), and a mean of 

0.9 billion barrels of 

undiscovered natural

gas liquids in the 

North Cuba Basin of 

Cuba.

Introduction

The U.S. Geological Survey (USGS) recently completed 

an assessment of the undiscovered oil and gas resources of the 

North Cuba Basin of northwestern Cuba (fig. 1). The extent of 

the Jurassic–Cretaceous Composite Total Petroleum System 

(TPS) defines the assessment area in this study (fig. 1). The 

composite TPS boundary is the postulated extent of petroleum 

migration from thermally mature Jurassic and possibly Cretaceous source rocks. The assessment of the North Cuba Basin 

is based on available information on the geologic elements of 

the composite TPS defined in the basin, including petroleum 

source rocks (source-rock maturation, petroleum generation and 

migration), reservoir rocks (sedimentology and petrophysical 

properties), and petroleum traps (trap formation and timing). By 

using this geologic framework, the USGS defined the Jurassic–

Cretaceous Composite TPS and three Assessment Units (AU) 

within the TPS, and we quantitatively estimated the undiscovered oil and gas resources within the three AUs (table 1).

The North Cuba Fold and Thrust Belt AU was defined to 

encompass all structures within the Late Cretaceous–Paleogene

fold and thrust belt in northwestern Cuba (fig. 1). The North 

Cuba Foreland Basin AU includes all potential oil and gas 

accumulations in the foreland basin that formed in front of the 

thrust belt, and it includes oil and gas accumulations in potential rift-related structures below rocks of the foreland basin. 

The North Cuba Platform Margin Carbonate AU includes all 

potential oil and gas accumulations in carbonate platformmargin reservoirs, including reef, reef-slope, and base-of-slope 

reservoirs. The geologic model used in the assessment has oil 

and gas generated from thermally mature, organic-rich Jurassic 

and possibly Cretaceous mudstones in the thrust belt. Oil and 

gas in the model migrate to the northwest, and they accumulate in structures in the fold and thrust belt, in reservoirs in the 

foreland basin, and in reservoirs in the margin of the carbonate 

platform (fig. 2). The main geologic uncertainties in the assessment are (1) the efficacy of lateral migration of petroleum from 

the thrust belt to the foreland basin and platform margin, and 

(2) the preservation of petroleum in traps since the generation 

and migration of petroleum in the Paleogene.

World Assessment of Oil and Gas Fact Sheet

Assessment of Undiscovered Oil and Gas Resources of 

the North Cuba Basin, Cuba, 2004

Figure 1. North Cuba Basin of northwestern Cuba. The Jurassic–Cretaceous Composite 

Total Petroleum System boundary (yellow line) encompasses the three assessment units (AU) 

defined and assessed in this study. Fine black lines on the ocean floor are faults; ball and bar 

on downthrown side.

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Conventional Oil

and Gas Resources

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Table 1. North Cuba Basin assessment results.

[MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For 

gas fields, all liquids are included under the NGL (natural gas liquids) category. F95 denotes a 95 percent chance of at least the amount tabulated. Other fractiles are 

defined similarly. Fractiles are additive only under the assumption of perfect positive correlation. Gray shading indicates not applicable.]

Figure 2. Schematic northwest–southeast cross section in the North Cuba Basin showing possible migration pathways of petroleum from 

source rocks within the fold and thrust belt into structures and reservoirs in the fold and thrust belt, in the foreland, and in the carbonate 

platform (after Magnier and others, 2004).

Resource Summary

The USGS assessed undiscovered conventional oil and gas 

resources in the North Cuba Basin, exclusive of reserve growth. 

The USGS estimated a mean of 4.6 billion barrels of oil (BBO), 

a mean of 9.8 TCF of natural gas (8.6 trillion cubic feet of 

associated-dissolved gas and 1.2 TCF of non-associated gas), 

and a mean total of 0.9 billion barrels of natural gas liquids 

for the three AUs (table 1). Of the mean of 4.6 BBO, about 

0.49 BBO are in the North Cuba Fold and Thrust Belt AU, 

about 3.2 BBO are in the North Cuba Foreland Basin AU, and 

about 0.9 BBO are estimated to be in the North Cuba Platform 

Margin Carbonate AU (table 1). All of the non-associated gas 

(1.2 TCF; gas in gas fields) was assessed in the North Cuba 

Foreland Basin AU.

For Further Information

Supporting geologic studies of the Composite Total Petroleum System and Assessment Units, and the methodology 

used in the North Cuba Basin assessment, are being prepared. 

Assessment results are available at the USGS Central Energy 

Resources Team Web site: http://energy.cr.usgs.gov/oilgas/.

North Cuba Basin Assessment Team

Christopher J. Schenk (Task Leader; schenk@usgs.gov), 

Thomas S. Ahlbrandt, Ronald R. Charpentier, Mitchell

E. Henry, Timothy R. Klett, Richard M. Pollastro, and 

Jean N. Weaver.

Reference Cited

Magnier, C., Moretti, I., Lopez, J.O., Gaumet, F., Lopez, 

J.G., and Letouzey, J., 2004, Geochemical characterization 

of source rocks, crude oils, and gases of northwest Cuba: 

Marine and Petroleum Geology, v. 21, p. 195–214.