U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2010–3096

October 2010

World Petroleum Resources Project

Assessment of Undiscovered Oil and Gas Resources of the 

Chad Basin Province, North-Central Africa

Printed on recycled paper

Introduction

The main objective of the U.S. Geological Survey’s (USGS) 

World Petroleum Resources Project is to assess the potential 

for undiscovered, technically recoverable oil and natural gas 

resources of the world, exclusive of the United States. As part 

of this program, the USGS recently completed an assessment of 

the Chad Basin Province (fig. 1). The Chad Basin is the largest 

intracratonic basin in north-central Africa that was influenced 

by Cretaceous and Tertiary rifting. The province covers an 

area of approximately 1,145,000 square kilometers (km2) and 

includes parts of Algeria, Cameroon, Chad, Niger, and Nigeria. 

This assessment was based on data from oil and gas wells and 

fields, field production records, and published geologic reports.

At the time of the assessment, the province contained eight oil 

fields—three in Chad and five in Niger—and is considered to be 

underexplored for its size. There are no gas fields in the province 

but several discoveries were reported to have associated gas. The 

oil fields and recent discoveries are limited to the CretaceousTertiary rift basins of Chad and Niger.

The Chad Basin Province was assessed for the first time 

because of increased exploratory activity and interest in its future 

potential. The assessment was based on geology and used the 

total petroleum system (TPS) concept. The geologic elements of 

a TPS include hydrocarbon source rocks (source rock maturation and hydrocarbon generation and migration), reservoir rocks

(quality and distribution), and traps for hydrocarbon accumulation. Using these geologic criteria, the USGS defined the 

Cretaceous-Tertiary Composite TPS with one assessment unit 

(AU), the Cretaceous-Tertiary Rifts AU (fig. 1), encompassing 

about 415,000 km2. The TPS was defined to include Cretaceous 

and Tertiary lacustrine and marine source rocks and the AU contains Cretaceous and Tertiary clastic reservoirs, shale seals, and 

traps that mostly are structural. 

The Chad Basin Province located in north-central Africa recently was assessed for undiscovered, technically recoverable 

oil, natural gas, and natural gas liquids resources as part of the U.S. Geological Survey’s (USGS) World Oil and Gas 

Assessment. Using a geology-based assessment methodology, the USGS estimated mean volumes of 2.32 billion barrels of 

oil, 14.65 trillion cubic feet of natural gas, and 391 million barrels of natural gas liquids.

C h a d

L a k e

C h a d

N i g e r

L i b y a

S u d a n

A l g e r i a

M a l i

E g y p t

B e n i n C a m e r o o n

C e n t r a l

A f r i c a n

R e p u b l i c

B u r k i n a

F a s o

N i g e r i a

T o g o

2°E 4°E 6°E 8°E 10°E 12°E 14°E 16°E 18°E 20°E 22°E 24°E 26°E

26°N

24°N

22°N

20°N

18°N

16°N

14°N

12°N

10°N

EXPLANATION

Chad Basin Province

 boundary

Cretaceous-Tertiary

 Rifts AU boundary

0

0

50 100 200 MILES

80 160 240 KILOMETERS

International boundary

Map

area

A A’

Figure 1. Locations of 

the Chad Basin Province 

and the CretaceousTertiary Rifts Assessment 

Unit (AU). Cross section 

A–A’ shown in figure 2.
The Cretaceous-Tertiary rift basins are filled with Lower 

Cretaceous to Neogene sedimentary rocks, ranging in thickness 

from about 3,000 meters (m) to more than 12,000 m (fig. 2) that 

were deposited in fluvial, lacustrine, and marine environments 

(Genik, 1992; Genik, 1993; Zanguina and others, 1998). During 

the Early Cretaceous fluvial and lacustrine rocks were deposited

in the rift basins of the Chad Basin. In the Late Cretaceous 

(Cenomanian to Maastrichtian) there was a marine transgression 

resulting from a regional sag event that formed a broad basin in 

which shallow marine to marginal marine and coastal plain rocks 

accumulated. During the Late Cretaceous to Oligocene, the last 

rifting phase occurred in the Chad Basin and thick fluvial and 

lacustrine rocks were deposited. The rift basins are known to 

contain Cretaceous and Tertiary lacustrine and marine source 

rocks that have generated hydrocarbons since the Late 

Cretaceous (Genik, 1993). The generated hydrocarbons migrated 

into Cretaceous and Tertiary reservoirs and structural traps.

West

A

Termit Basin

P P

Ku

HM Ku

Kl

Kl

Sedigi-1

1975

Kumia-1

1976

pe

pe

DEPTH IN KILOMETERS 0

5

10

15

East

A’

0 20 40

0 25 MILES

50 KILOMETERS

Province, Total Petroleum

Systems (TPS) and

Assessment Unit (AU) 

Field 

Type

Largest 

Expected 

Mean

Field Size

Total Undiscovered Resources

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

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

Chad Province–Cretaceous-Tertiary Composite TPS

Cretaceous-Tertiary Rifts AU

Oil 387 794 2,082 4,637 2,315 228 657 1,665 766 6 18 46 21

Gas 2,320 4,786 12,443 28,002 13,882 125 330 751 370

Total Conventional

Resources 794 2,082 4,637 2,315 5,014 13,100 29,667 14,648 131 348 797 391

[Largest expected mean field size in million barrels of oil and billion cubic feet of gas; 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 natural gas liquids (NGL). 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. AU, assessment unit;

AU probability is the chance of at least one accumulation of minimum size within the AU. NGL, natural gas liquids. TPS, total petroleum system. Gray shading indicates not

applicable]

Table 1. Chad Provinces assessment results for undiscovered, technically recoverable oil, gas, and natural gas liquids.

References

Genik, G.J., 1992, Regional framework, structural and petroleum

aspects of rift basins in Niger, Chad and the Central African 

Republic (C.A.R.): Tectonophysics, v. 213, no. 1, 

p. 169–185.

Genik, G.J., 1993, Petroleum geology of the CretaceousTertiary rifts basins in Niger, Chad, and Central African 

Republic: American Association of Petroleum Geologists Bulletin v. 73, no. 8, p. 153–168.

Zanguina, M., Bruneton, A., and Gonnard, R., 1998, An introduction to the petroleum potential of Niger: Journal of Petroleum 

Geology, v. 21, no. 1, p. 83–103.

Figure 2. Schematic cross section showing the sedimentary fill of the southern part of the Termit rift basin in the 

Chad Basin Province, north-central Africa. Location of cross section shown in figure 1. pe, Precambrian; Kl, Lower 

Cretaceous; Ku, Upper Cretaceous; P, Paleogene; HM, Holocene to Miocene. Modified after Genik (1993).

Resource Summary

Using a geology-based assessment, the USGS estimated 

mean volumes of undiscovered, technically recoverable conventional oil and gas resources for the Cretaceous-Tertiary Rifts 

AU in the Chad Basin Province (table 1). The mean volumes are 

estimated at 2,315 million barrels of oil (MMBO), 14,648 billion 

cubic feet of gas (BCFG), and 391 million barrels of natural gas 

liquids. The estimated mean size of the expected largest oil field 

is 387 MMBO and the estimated mean size of the expected largest gas field is 2,320 BCFG.

For Additional Information

Assessment results are available at the USGS Central 

Energy Resources Science Center Web site: http://energy.cr.usgs.

gov/oilgas/noga/ or contact Michael E. Brownfield, the assessing 

geologist (mbrownfield@usgs.gov).

Chad Basin Provinces Assessment Team

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

Charpentier, Timothy R. Klett, Troy A. Cook, Richard M. 

Pollastro, and Marilyn E. Tennyson.