U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3030

April 2012

World Petroleum Resources Project

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 South Africa Coastal 

Province (fig. 1), an area of about 367,550 square kilometers (km2) that 

covers part of the southern offshore and onshore of South Africa. This 

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

published geologic reports.

The basic geologic framework of the offshore part of the South 

Africa Coastal Province developed in two phases: (1) a syn-rift phase 

that was initiated during the Jurassic and continued into the Lower Cretaceous and resulted in the formation of grabens and half-grabens, and 

(2) a transform-drift-passive margin phase that began in the late Albian 

and continues to the present. The total thickness of the Mesozoic to 

Cenozoic stratigraphic section is more than 5,000 meters (m) on the 

outer parts of the continental shelf (fig. 2).

The South Africa Coastal Province was assessed for the first time 

because of increased interest in its future potential. The assessment was 

geology based 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 Mesozoic 

Composite TPS with one assessment unit (AU), the Mesozoic–Cenozoic Reservoirs AU (fig. 1), encompassing 212,652 km2

 that includes 

the offshore part of the province to a water depth of 4,000 m. The TPS 

was defined to include Middle to Upper Jurassic lacustrine source 

rocks containing 1.0 to 3.7 weight percent total organic carbon (TOC) 

and Cretaceous marine source rocks, including Aptian strata containing 

Type II kerogen ranging from 2.0 to 4.3 weight percent TOC and the 

Cenomanian–Turonian strata containing Type II kerogen ranging from 

1.0 to 3.0 weight percent TOC.

The Mesozoic–Cenozoic Reservoirs AU contains Cretaceous and 

lower Paleogene clastic reservoirs and traps that mostly are associated 

with growth fault-related structures, rotated fault blocks within the 

continental shelf, deep water fans, turbidite channels and sandstones, 

slope truncations along the present-day shelf and paleoshelf edge, and 

Cretaceous and Paleogene stratigraphic pinch-outs along the southern 

AU margin. Possible Jurassic and Lower Cretaceous syn-rift reservoirs 

are associated with the grabens and half grabens in the deeper parts of 

the offshore. The primary seals are Cretaceous and Paleogene marine 

mudstones and shales. At the time of the assessment, only 183 exploration wells had been drilled since 1969, resulting in the discovery of 

7 oil and 17 gas accumulations exceeding the minimum size of 5 million 

Figure 1. Locations of 

the South Africa Coastal 

Province and Mesozoic−

Cenozoic Reservoirs 

Assessment Unit (AU), 

South Africa. Cross section 

shown in figure 2.

BOTSWANA

SOUTH AFRICA

LESOTHO

SWAZILAND

MOZAMBIQUE

NAMIBIA

A

A’

16° 18° 20° 22° 24° 26° 28° 30° 32° 34°

24°

26°

28°

30°

32°

34°

36°

38°

SOUTH 

ATLANTIC 

OCEAN

 INDIAN

OCEAN

0 150 300 MILES

0 150 300 KILOMETERS

AFRICA

MADAGASCAR

 INDIAN

SOUTH OCEAN

ATLANTIC

OCEAN

EXPLANATION

South African Coastal Province

Mesozoic-Cenozoic Reservoirs AU 

Assessment of Undiscovered Oil and Gas Resources of the South Africa Coastal 

Province, Africa

The South Africa Coastal Province along the South Africa coast 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 2.13 billion barrels of oil, 35.96 trillion 

cubic feet of natural gas, and 1,115 million barrels of natural gas liquids.
barrels of oil equivalent and 30 billion cubic feet of gas. The AU is 

considered to be underexplored for its size.

Exploration wells and discovered accumulations on the continental shelf and upper slope (IHS Energy, 2009) provide evidence for 

(1) the existence of an active petroleum system containing Cretaceous 

marine source rocks that have produced hydrocarbons most likely since 

the Late Cretaceous, and (2) the migration of hydrocarbons into Cretaceous and Paleogene reservoirs.

Resource Summary

Using a geology-based assessment, the USGS estimated mean 

volumes of undiscovered, technically recoverable conventional oil 

and gas resources for the Mesozoic−Cenozoic Reservoirs AU in the 

South Africa Coastal Province at 2,129 million barrels of oil (MMBO), 

35,964 billion cubic feet of gas (BCFG), and 1,115 million barrels of 

natural gas liquids (table 1). The estimated mean size of the largest oil 

field that is expected to be discovered is 340 MMBO, and the estimated 

mean size of the expected largest gas field is 2,937 BCFG. For this 

assessment, a minimum undiscovered field size of 5 million barrels of 

oil equivalent (MMBOE) was used. No attempt was made to estimate 

economically recoverable reserves.

References Cited

Davies, C.P.N., 1997, Hydrocarbon evolution of the Bredasdorp Basin, 

offshore South Africa—From source to reservoir: Stellenbosch, 

South Africa, University of Stellenbosch, Ph.D. dissertation, 1123 p.

IHS Energy, 2009, International petroleum exploration and production 

database [current through December 2009]: Available from IHS 

Energy, 15 Inverness Way East, Englewood, CO 80112 USA.

For Additional Information

Assessment results are available at the USGS Central Energy 

Resources Science Center website: http://energy.cr.usgs.gov/oilgas/

noga/ or contact Michael E. Brownfield, the assessing geologist 

(mbrownfield@usgs.gov).

Offshore South Africa Province Assessment 

Team

Michael E. Brownfield, Christopher J. Schenk, Ronald R. Charpentier, Timothy R. Klett, Troy A. Cook, and Richard M. Pollastro.

Sea floor

22A11

15A11

13A11

14A11

5A11

1A11

D

SOUTHWEST NORTHEAST

A A’

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Depth, in meters

AGULHAS

ARCH

INFANTA

0 5 MILES ARCH

0 5 KILOMETERS

F-A Gas field ? ?

?

?

22A11 Major sequence boundary

Source shale interval

(?-indicates minor

 or speculative)

Drift marine claystone, turbidites

and shelf sandstones

Synrift interbedded fluvial,

shallow marine sediments

(local evaporites in Bredasdorp basin)

Sandstones

Tertiary shelf sediments

Cape Supergroup

Gas discoveries

Oil discoveries

EXPLANATION BOTSWANA

SOUTH AFRICA

LESOTHO

SWAZILAND

MOZAMBIQUE NAMIBIA

16° 18° 20° 22° 24° 26° 28° 30° 32° 34°

24°

26°

28°

30°

32°

34°

36°

38°

SOUTH 

ATLANTIC 

OCEAN

 INDIAN

OCEAN

A A’

Figure 2. Southwest to northeast schematic cross section showing major faults, hydrocarbon discoveries, source rocks, and 

major sequence boundaries in the Bredasdorp Basin. Modified after Davies (1997).

Province, total petroleum

systems (TPS) and 

assessment units (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

South Africa Coastal Province–Mesozoic Composite TPS

Mesozoic-Cenozoic

Reservoirs AU

Oil

Gas

Total coventional

resources

Table 1. South Africa Coastal Province assessment results for undiscovered, technically recoverable oil, gas, and natural gas liquids.

2,937

340

924 1,984 3,851 2,129

924 1,984 3,851 2,129 1,209 2,728 5,657 2,995 32 74 155 81

15,915 30,931 57,024 32,969 496 968 1,794 1,034

17,124 33,659 62,681 35,964 528 1,042 1,949 1,115

[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. TPS, total petroleum system. Gray shading indicates not 

applicable]