U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3046

May 2012

World Petroleum Resources Project

Assessment of Undiscovered Conventional Oil and Gas 

Resources of South America and the Caribbean, 2012

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.

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.

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.

Figure 1. Locations of 31 provinces of South America and Caribbean 

assessed in this study. Province numbers and names are included in table 1.

SOUTH ATLANTIC OCEAN

NORTH ATLANTIC OCEAN

SOUTH PACIFIC 

OCEAN

30

31

29

28

26 25

27

21

20

22

23

24

12

1

5

6

2

3

7

13

4

8

9

10

11

14 15

16

17

19

18

30°35°40°45°50°55°60°65°70°75°80°85°90°

25°

20°

15°

10°

5°

0°

5°

10°

15°

20°

25°

30°

35°

40°

45°

50°

55°

0 500 1,000 KILOMETERS

0 500 1,000 MILES
Table 1. South America and Caribbean assessment results for undiscovered, technically recoverable oil, gas, and natural gas liquids.

[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 accumulations, all liquids are included as NGL (natural gas liquids). Undiscovered gas resources are the sum of nonassociated and associated gas. 

F95 represents a 95-percent chance of at least the amount tabulated; other fractiles are defined similarly. Fractiles are additive under assumption of perfect positive correlation. Gray shading indicates not applicable]

Map 

location 

number

Province name Province

code

Field 

type

Total undiscovered resources

Oil (MMBO) Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

1 Solimoes Basin 6011 Oil 260 536 1,018 574 2,108 4,358 8,316 4,673 45 104 229 116

Gas 9,420 17,317 31,363 18,454 260 478 867 509

2 Amazonas Basin 6012 Oil 130 330 742 369 1,057 2,684 6,061 3,005 22 63 168 75

Gas 2,709 6,024 12,734 6,648 75 166 351 184

3 Parnaiba Basin 6016 Oil 1,397 2,786 5,201 2,972 11,357 22,662 42,414 24,197 247 542 1,137 598

Gas 8,342 16,628 31,114 17,759 230 459 860 490

4 Parana Basin 6020 Oil 188 400 770 429 1,527 3,250 6,275 3,492 32 76 175 86

Gas 3,240 6,215 11,364 6,610 140 272 502 289

5 Guyana-Suriname Basin 6021 Oil 5,167 12,494 25,981 13,608 6,998 18,284 45,230 21,196 186 490 1,244 574

Gas 4,253 9,887 20,664 10,836 111 262 561 289

6 Foz do Amazonas Basin 6022 Oil 201 583 1,511 684 251 848 2,638 1,075 7 23 73 29

Gas 16,136 31,742 58,701 33,786 813 1,600 2,963 1,704

7 Sergipe-Alagoas Basin 6029 Oil 561 1,684 4,425 1,986 1,203 3,683 10,227 4,435 72 223 635 271

Gas 644 2,704 11,729 3,902 38 163 709 236

8 Espirito Santo Basin 6034 Oil 334 1,329 5,508 1,908 638 2,697 11,840 4,011 10 49 235 76

Gas 3,285 10,983 39,831 14,803 107 386 1,485 536

9 Campos Basin 6035 Oil 1,924 7,807 44,836 14,736 1,192 10,256 95,243 27,560 28 297 2,896 829

Gas 115 1,142 22,502 5,302 4 36 703 167

10 Santos Basin 6036 Oil 23,839 54,434 113,392 59,689 56,405 131,477 291,722 147,515 1,668 3,853 8,514 4,309

Gas 10,203 43,103 182,998 62,305 302 1,284 5,448 1,857

11 Pelotas Basin 6037 Oil 244 664 1,736 782 557 1,526 4,090 1,817 34 93 249 110

Gas 8,104 17,505 34,141 18,817 173 378 754 410

12 Putamayo-Oriente-Maranon Basin 6041 Oil 3,157 4,585 6,633 4,698 1,411 2,092 3,061 2,144 37 56 82 57

Gas 0 0 0 0 0 0 0 0

13 Santa Cruz-Tarija Basin 6045 Oil 60 111 196 118 249 475 866 505 5 11 19 11

Gas 11,091 24,012 47,595 26,016 468 1,033 2,156 1,137

14 Salado-Punta del Este Basin 6054 Oil 643 1,752 4,064 1,975 1,471 4,058 9,503 4,593 89 246 580 279

Gas 8,129 19,910 43,735 22,180 173 432 960 482

15 Neuquen Basin 6055 Oil 153 311 591 334 206 446 955 497 4 9 21 10

Gas 1,511 3,427 7,230 3,777 23 53 116 59

16 San Jorge Basin 6058 Oil 33 63 116 67 23 46 93 51 0 1 2 1

Gas 95 195 373 210 2 4 7 4

17 Magallanes Basin 6059 Oil 60 163 501 205 134 379 1,249 497 2 5 15 6

Gas 2,747 5,510 10,412 5,896 73 159 339 176

18 Falklands Plateau 6060 Oil 1,457 4,413 12,224 5,302 3,215 9,837 28,575 12,060 40 125 372 154

Gas 10,584 32,885 88,316 38,940 257 820 2,478 1,024

19 Malvinas Basin 6063 Oil 38 118 307 138 85 277 774 333 1 3 10 4

Gas 2,560 5,394 10,227 5,760 67 156 333 172

20 Upper Magdelena Basin 6089 Oil 163 357 729 390 225 502 1,077 556 5 10 22 11

Gas 81 358 1,424 499 1 5 22 8

21 Middle Magdelena Basin 6090 Oil 238 495 959 534 384 840 1,850 942 6 13 29 15

Gas 131 490 1,831 666 2 7 28 10

22 Lower Magdelena Basin 6091 Oil 15 66 286 97 45 199 867 293 1 4 18 6

Gas 971 2,584 6,211 2,951 70 189 470 218

23 Guarija Basin 6095 Oil 6 36 208 63 18 108 629 190 0 2 13 4

Gas 578 1,982 5,554 2,385 12 41 118 50

24 Llanos Basin 6096 Oil 957 2,418 5,215 2,665 1,702 4,545 11,008 5,219 55 151 376 175

Gas 599 2,350 8,789 3,184 61 245 943 338

25 Barinas-Apure Basin 6097 Oil 90 398 1,567 551 7 29 114 40 0 1 2 1

Gas 42 400 3,447 887 0 4 35 9

26 East Venezuela Basin 6098 Oil 1,138 2,944 7,126 3,379 3,837 9,914 24,081 11,410 82 214 538 249

Gas 11,269 26,387 55,483 28,938 301 729 1,605 810

27 Maracaibo Basin 6099 Oil 340 838 1,822 929 637 1,693 4,178 1,959 26 69 174 80

Gas 1,584 4,938 13,934 5,969 45 142 401 172

28 Tobago Trough 6103 Oil 0 0 0 0 0 0 0 0 0 0 0 0

Gas 6,558 14,554 29,048 15,742 22 54 140 65

29 Barbados Accretionary Prism 6107 Oil 22 92 498 154 33 168 1,028 310 1 6 39 12

Gas 4,184 12,550 32,009 14,599 92 289 783 344

30 North Cuba Basin of Greater Antilles Deformed Belt 6117 Oil 1,185 4,301 9,364 4,660 1,865 7,558 17,961 8,432 163 709 1,825 814

Gas 141 862 3,418 1,190 7 44 185 63

31 Bahamas Platform 6119 Oil 554 1,591 4,336 1,906 692 2,028 5,736 2,467 42 126 362 155

Gas 705 2,723 12,170 4,051 11 45 212 70

Total conventional resources 44,556 108,098 261,862 125,900 229,547 571,684 1,476,008 678,537 6,850 17,507 46,581 21,001
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.

Eocene turbidites of the Scotland District, Barbados. Photograph by C.J. Schenk, 

U.S. Geological Survey, 2011.

South America−Caribbean Assessment Team

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

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

Richard M. Pollastro, and Marilyn E. Tennyson.

For Further Information

Supporting studies of the geologic 

models and the methodology used in 

the assessment of South America and 

Caribbean provinces are in progress. 

Assessment results are available at the 

USGS Energy Program website, 

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

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.