U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3147 

February 2013

World Petroleum Resources Project

Assessment of Undiscovered Conventional Oil and Gas 

Resources of North Africa, 2012

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 19 billion barrels 

of technically recoverable undiscovered conventional oil and 370 trillion cubic feet of undiscovered conventional natural 

gas resources in 8 geologic provinces of North Africa.

Introduction

The U.S. Geological Survey (USGS) assessed the potential for undiscovered conventional oil and gas accumulations 

within priority geologic provinces of North Africa as part of 

the USGS World Petroleum Resources Project. Eight priority 

geologic provinces were assessed in this study, which represents a reassessment of North Africa last published in 2000 

(U.S. Geological Survey World Energy Assessment Team, 

2000). The eight geologic provinces include (1) Nile Delta 

Basin; (2) Sirte Basin; (3) Pelagian Basin; (4) Trias/Ghadames 

Basin; (5) Hamra Basin; (6) Illizi Basin; (7) Grand Erg/Ahnet 

Basin; and (8) Essaouira Basin (fig. 1). Resource estimates 

for the Nile Delta, Sirte, and Pelagian Basin provinces were

published previously (Kirschbaum and others, 2010; Whidden 

and others, 2011), but are included here for a more complete 

view of undiscovered conventional oil and gas resources across 

North Africa.

The assessment methodology included a complete geologic framework description for each province based mainly on 

published literature and definitions of petroleum systems and 

assessment units (AU) within these systems. Exploration and 

discovery history data were a critical part of the methodology 

used to estimate sizes and numbers of undiscovered conventional 

accumulations. Each AU 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.

Figure 1. Locations of eight priority geologic provinces of North Africa assessed in this study of undiscovered conventional oil and 

gas resources.

Nile Delta Basin

Sirte Basin

Pelagian Basin

Trias/Ghadames 

Basin

Illizi Basin

Hamra Basin

Grand Erg/Ahnet Basin

Essaouira 

Basin

ALGERIA

LIBYA

EGYPT

SUDAN

NIGER

MALI

WESTERN

SAHARA

MAURITANIA

SPAIN TURKEY

CHAD

MOROCCO

TUNISIA

ITALY

PORTUGAL GREECE

MEDITERRANEAN

SEA

NORTH 

ATLANTIC

OCEAN

-10° -5° 0° 5° 10° 15° 20° 25° 30° 35°

40°

35°

30°

25°

20°

0 200 400 KILOMETERS

0 200 400 MILES North Africa

assessment

area

AFRICA

EXPLANATION

Assessed Provinces
Resource Summary

The USGS assessed undiscovered conventional oil and 

gas resources in 18 AUs within eight geologic provinces, with 

the following estimated mean totals: (1) for conventional oil 

resources, 18,618 million barrels of oil (MMBO), with a range 

from 6,846 to 37,460 MMBO; (2) for undiscovered conventional gas, 370,375 billion cubic feet of gas (BCFG), with a 

range from 149,541 to 712,430 BCFG; and (3) for natural gas 

liquids (NGL), 12,553 MMBNGL, with a range from 4,809 to 

24,785 MMBNGL.

Of the mean undiscovered conventional oil resource of 

18,618 MMBO, about 41 percent (7,557 MMBO) is estimated 

to be in the Offshore Salt Structures AU, offshore Morocco.

Other significant AUs for potential undiscovered oil include 

the Offshore Sirte Basin AU (2,267 MMBO), Onshore Sirte 

Carbonate-Clastic AU (1,278 MMBO), and the Berkine Paleozoic and Mesozoic Reservoirs AU (1,839 MMBO) of the Trias/

Ghadames Basin. Of the mean undiscovered gas resource of 

370,375 BCFG, about 59 percent (217,313 BCFG) is estimated 

to be in the Nile Cone AU. Other significant AUs for potential 

undiscovered gas resources include the Offshore Salt Structures 

AU of Morocco (45,208 BCFG), the Offshore Sirte Basin AU 

(22,637 BCFG), and the Gourara Paleozoic Reservoirs AU 

(15,559 BCFG) of the Grand Erg/Ahnet Basin Province. These 

four AUs encompass about 81 percent of the undiscovered 

gas resource. 

Hoodoos (thin spires of rock) in the 

Sahara Desert, Egypt. Hoodoos are 

composed of fine-grained, chalky 

limestone. Photo by K.J. Whidden, 2005.

Linear dune in the Sahara Desert, Egypt. Photo by K.J. Whidden, 2005.
Table 1. Assessment results for undiscovered conventional oil and gas resources for provinces of North Africa.

[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) category. Undiscovered gas resources are the sum of nonassociated (gas in gas fields) and associated 

gas (gas in oil fields). F95 represents a 95 percent chance of at least the amount tabulated–other fractiles are defined similarly. Fractiles are additive under the assumption of perfect positive correlation. Shading indicates not applicable]

Total petroleum systems 

(TPS) 

and assessment units (AU)

Field 

type

Expected 

largest

field size

Total undiscovered resources

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

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

Nile Delta Basin Province, Mesozoic-Cenozoic Composite TPS

Nile Margin Reservoirs AU

Oil 214 449 1,150 2,600 1,288 551 1,425 3,237 1,597 11 29 66 32

Gas 766 698 2,193 5,750 2,574 21 68 181 80

Nile Cone AU

Oil 311 42 256 1,666 475 152 930 6,123 1,758 6 38 255 73

Gas 17,194 91,213 197,850 410,825 217,313 2,413 5,269 10,962 5,789

Sirte Basin Province, Sirte-Rachmat Composite TPS

Onshore Sirte Carbonate-Clastic AU

Oil 432 364 1,087 2,823 1,278 418 1,338 4,035 1,673 22 74 240 96

Gas 2,042 1,267 4,179 12,569 5,169 44 151 478 192

Offshore Sirte Basin AU

Oil 857 563 1,838 5,457 2,267 633 2,250 7,677 2,972 34 124 454 170

Gas 6,843 6,591 19,540 49,077 22,637 233 709 1,903 840

Pelagian Basin Province, Bou Dabbous-Cenozoic TPS

Bou Dabbous-Cenozoic 

Structural/Stratigraphic AU

Oil 60 130 283 552 305 45 113 274 131 1 3 8 4

Gas 616 1,443 2,933 5,405 3,119 37 75 140 80

Pelagian Basin Province, Jurassic-Cretaceous Composite TPS

Jurassic-Cretaceous 

Structural/Stratigraphic AU

Oil 13 62 116 212 124 79 154 287 165 2 4 7 4

Gas 569 1,044 2,409 5,023 2,643 32 73 154 80

Trias/Ghadames Basin Province, Paleozoic Composite TPS

Oued Mya Paleozoic

Reservoirs AU

Oil 96 631 1,004 1,539 1,035 480 768 1,180 791 20 32 49 33

Gas 249 363 753 1,573 831 24 54 128 63

Melrhir Paleozoic 

Reservoirs AU

Oil 12 195 287 419 294 103 153 225 157 4 6 9 6

Gas 65 571 861 1,270 883 52 79 117 81

Berkine Paleozoic and 

Mesozoic Reservoirs AU

Oil 194 1,101 1,786 2,777 1,839 2,484 4,169 6,792 4,338 130 221 365 231

Gas 450 1,157 2,138 3,751 2,255 72 135 244 143

Hamra Basin Province, Silurian/Upper Devonian-Ghadames/Berkine Composite TPS

Hamra Deep Structures 

and Subcrop AU

Oil 69 124 430 841 451 232 836 1,801 902 9 32 76 36

Gas 378 556 2,010 4,088 2,130 51 195 437 213

Hamra Basin Margin 

Structures AU

Oil 73 42 190 499 220 79 369 1,042 439 3 14 43 18

Gas 266 79 400 1,411 525 8 39 143 52

Al Atshan Saddle AU

Oil 44 13 66 232 87 25 130 476 174 1 5 20 7

Gas 267 81 399 1,421 526 7 39 145 53

Sirte Basin Subcrop AU

Oil 19 0 18 86 26 0 35 175 52 0 1 7 2

Gas 0 0 0 0 0 0 0 0

Illizi Basin Province, Paleozoic Composite TPS

Illizi Paleozoic Reservoirs AU

Oil 177 537 973 1,650 1,017 1,998 3,673 6,456 3,884 35 65 115 69

Gas 1,411 7,124 11,800 18,515 12,176 508 879 1,458 918

Grand Erg/Ahnet Basin Province, Paleozoic Composite TPS

Gourara Paleozoic Reservoirs AU

Oil 22 125 217 365 227 275 493 846 518 5 9 15 9

Gas 1,125 8,538 14,893 24,989 15,559 14 25 47 27

Ahnet Paleozoic 

Reservoirs AU

Oil 0 0 0 0 0 0 0 0 0 0 0 0

Gas 155 2,419 3,994 6,571 4,176 3 4 7 4

Essaouira Basin Province, Paleozoic-Mesozoic Composite TPS

Essaouira Basin AU

Oil 42 52 116 246 128 53 122 268 136 1 3 7 4

Gas 253 315 691 1,474 766 10 22 49 25

Offshore Salt Structures AU

Oil 1,788 2,416 6,715 15,496 7,557 3,794 10,759 25,476 12,198 100 286 697 328

Gas 10,778 14,681 40,352 92,348 45,208 896 2,482 5,759 2,791

Total conventional

 resources 6,846 16,532 37,460 18,618 149,541 335,112 712,430 370,375 4,809 11,244 24,785 12,553
For Further Information

Supporting studies of the geologic models and the methodology used in the assessment of North African provinces are in 

progress. Assessment results are available at the USGS Energy 

Program Web site, http://energy.cr.usgs.gov/oilgas/. 

North Africa Provinces Assessment Team: 

Christopher J. Schenk, Timothy R. Klett, Katherine J. 

Whidden, Mark A. Kirschbaum, Ronald R. Charpentier, Troy 

A. Cook, Michael E. Brownfield, and Janet K. Pitman.

References Cited

Kirschbaum, M.A., Schenk, C.J., Charpentier, R.R., Klett, 

T.R., Brownfield, M.E., Pitman, J.K., Cook, T.A., and Tennyson, M.E., 2010, Assessment of undiscovered oil and gas 

resources of the Nile Delta Province, Eastern Mediterranean: 

U.S. Geological Survey Fact Sheet FS 2010–3027, 4 p.

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.

Whidden, K.J., Lewan, M.D., Schenk, C.J., Charpentier, R.R., 

Cook, T.A., Klett, T.R., and Pitman, J.K., 2011, Assessment 

of undiscovered oil and gas resources of Libya and Tunisia, 

2010: U.S. Geological Survey Fact Sheet FS 2011–3105, 2 p.

Sinuosity in a linear dune, Sahara Desert, Egypt. Note four-wheel drive vehicle for scale. 

Photo by K.J. Whidden, 2005.