Assessment of undiscovered conventional oil and gas resources of South America and the Caribbean, 2012

World Petroleum Resources Project

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 126 billion barrels of oil and 679 trillion cubic feet of undiscovered natural gas in 31 geologic provinces of South America and the Caribbean.

Introduction

The U.S. Geological Survey (USGS) assessed the potential for undiscovered conventional oil and gas fields within priority geologic provinces of South America and the Caribbean as part of the USGS World Petroleum Resources Project (fig. 1). Thirty-one geologic provinces were assessed in this study, which represents a complete re-assessment of the South America−Caribbean region published in 2000 (U.S. Geological Survey World Energy Assessment Team, 2000).

The methodology for the assessment included a complete geologic framework description for each province based mainly on published literature and definition of petroleum systems and assessment units (AU) within these systems. Exploration and discovery history was a critical part of the methodology to determine sizes and numbers of undiscovered accumulations. In those AUs with few or no discoveries, geologic and production analogs were used to estimate sizes and numbers of undiscovered oil and gas accumulations. Each assessment unit was assessed for undiscovered oil and nonassociated gas accumulations, and co-product ratios were used to calculate the volumes of associated gas (gas in oil fields) and volumes of natural gas liquids. This assessment is for conventional oil and gas resources only; unconventional resource assessments (shale gas, shale oil, tight gas) for this region are being completed in a separate study.

The provinces assessed in this study represent a wide range of tectonic settings and evolution, stratigraphic fill, thermal evolution, petroleum systems, and exploration history. There are many provinces in this region that have been maturely explored, such as Maracaibo Basin, Neuquen Basin, Magallanes Basin, and Llanos Basin, whereas several provinces have few or no discoveries, such as Salado-Punta del Este, Parnaiba, and Bahama Platform. The range of resource estimates for each province reflects the geologic uncertainty.

Figure 1. Locations of 31 provinces of South America and Caribbean assessed in this study. Province numbers and names are included in table 1.

Resource Summary

The USGS assessed undiscovered conventional oil and gas resources in assessment units within 31 geologic provinces (table 1). For undiscovered resources, the mean totals are as follows: (1) 125,900 million barrels of oil (MMBO), with a range from 44,556 to 261,862 MMBO; (2) 678,537 billion cubic feet of gas (BCFG), with a range from 229,547 to 1,476,008 BCFG; and (3) 21,001 million barrels of natural gas liquids (MMBNGL), with a range from 6,850 to 46,581 MMBNGL.

Eocene turbidites of the Scotland District, Barbados. Photograph by C.J. Schenk, U.S. Geological Survey, 2011.

Of the mean oil total of 125,900 MMBO, about 44 percent (55,601 MMBO) is estimated to be in subsalt reservoirs in the Santos, Campos, and Espirito Santo Basin Provinces, with most undiscovered subsalt oil estimated to be in the Santos Basin Province. In addition, several provinces are estimated to have significant undiscovered conventional oil potential, including the Guyana−Suriname Basin Province (mean of 13,608 MMBO); Falklands Plateau Province (mean of 5,302 MMBO); Putumayo−Oriente−Maranon Basin Province (mean of 4,698 MMBO); North Cuba Basin Province (mean of 4,660 MMBO); and the Parnaiba Basin Province (mean of 2,972 MMBO).

For the mean undiscovered conventional gas total of 678,537 BCFG, about 55 percent (374,956 BCFG) is estimated to be in five provinces: (1) Santos Basin Province (mean of 209,820 BCFG); (2) Falklands Plateau Province (mean of 51,000 BCFG), (3) Parnaiba Basin Province (mean of 41,956 BCFG), (4) East Venezuela Basin Province (mean of 40,348 BCFG), and (5) Guyana−Suriname Basin Province (mean of 32,032 BCFG).

Cliffs of carbonate rock along the east coast of the island of Barbados. Photograph by C.J. Schenk, U.S. Geological Survey, 2011.

Reference Cited

U.S. Geological Survey World Energy Assessment Team, 2000, U.S. Geological Survey world petroleum assessment 2000—Description and results: U.S. Geological Survey Digital Data Series DDS-60, 4 CD-ROMs.

For Further Information

Supporting studies of the geologic models and the methodology used in

South America−Caribbean Assessment Team

the assessment of South America and Caribbean provinces are in progress.

Christopher J. Schenk, Michael E. Brownfield, Ronald R. Charpentier,

Assessment results are available at the

Troy A. Cook, Timothy R. Klett, Mark A. Kirschbaum, Janet K. Pitman,

USGS Energy Program website,

Richard M. Pollastro, and Marilyn E. Tennyson.

http://energy.usgs.gov/oilgas/.

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