U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2014–3082

September 2014

National and Global Petroleum Assessment Project

Assessment of Potential Shale-Oil and Shale-Gas Resources 

in Silurian Shales of Jordan, 2014

Using a geology-based assessment methodology, the U.S. 

Geological Survey estimated means of 11 million barrels 

of potential shale-oil and 320 billion cubic feet of shale-gas 

resources in Silurian shales of Jordan.

Figure 1. Map showing locations of three areas of Jordan 

assessed in this study.

Introduction

The U.S. Geological Survey (USGS) quantitatively assessed 

the potential for shale-oil and shale-gas resources in the Silurianage source-reservoir rock system of Jordan (fig. 1). This study 

did not include the potential for oil-shale resources of Jordan, 

which should not be confused with shale-oil resources. Oil 

shale is a rock in which the organic matter that is the precursor 

to oil (kerogen) remains thermally immature and oil has not 

been generated, whereas shale oil is thermally mature oil that 

is generated and remains within the source rock. Undiscovered 

conventional oil and gas resources were assessed in Jordan in 

2012 as part of the Middle East region (Pitman and others, 2012).

The tectonic history of Jordan had a significant effect on 

retention of hydrocarbons generated within the Silurian sourcereservoir rock system. Organic-rich Silurian marine shales in 

parts of Jordan were thermally mature with respect to oil and 

gas generation prior to the Hercynian orogeny, which took place 

from Devonian through Carboniferous time. Uplift and erosion 

on the order of 2,500 meters (m) or more during this orogeny 

led to significant risk with respect to retention of oil and gas 

within the source rock (Skarpnes and Hagen, 2008). Retention 

risk was a major part of the geologic evaluation prior to the 

quantitative assessment.

To be considered for a USGS assessment, any sourcereservoir rock system must (1) have greater than 2 weight percent 

total organic carbon (TOC); (2) be within the proper thermal 

maturity window for oil or gas generation; (3) have greater than 

15 m of organic-rich shale; (4) contain Type I or II organic matter, 

and (5) occur at depths greater than 1,500 m (Charpentier and 

Cook, 2011). Areas that do not meet these criteria are unlikely to 

have significant resource potential without major technological 

improvements or major price increases. Once potential areas for 

assessment are defined, the tectonic history, thermal history, and 

timing of maturation and generation are used to evaluate the risk 

of retention of hydrocarbons within the source rock.

Three assessment units (AUs) were defined in this study. 

The AUs correspond to areas in Jordan where organic-rich Type 

II Silurian marine shales are thermally mature for oil or gas, are 

greater than 15 m thick, and have greater than 2 weight percent 

TOC (fig. 1). The Sirhan Area Jordan Silurian Shale Oil AU was 

defined to encompass potential thermally mature, oil-bearing 

Silurian shales in the Sirhan area. Uplift and erosion on the 

order of 2,500 m or more resulted in most of the shale being 

less than 1,500 m deep. The uplift history is interpreted to have 

significantly reduced the potential for shale-oil resources. The 

East Safawi Area Jordan Silurian Shale Oil AU defines an area 

of potential thermally mature oil-bearing shales in northeast 

Jordan. In this area, uplift resulted in partial erosion of Silurian 

shales, providing a high risk for retention for oil in the source 

rock-reservoir system. The Risha Area Jordan Silurian Shale 

Gas AU was defined to encompass potential gas-bearing Silurian 

shales in the Risha area. Uplift and erosion in this area was 

perhaps on the order of 1,200 m, and is interpreted to have had 

SYRIA

LEBANON

IRAQ

JORDAN

SAUDI ARABIA

ISRAEL

WEST

BANK 

MEDITERRANEAN

SEA

GULF

OF

AQABA

DEAD

SEA

 SEA OF

GALILEE

35° 36° 37° 38° 39°

34°

33°

32°

31°

30°

29°

SAUDI

EGYPT ARABIA

IRAQ

JORDAN

SYRIA

ISRAEL

 WEST

 BANK

LEBANON

RED

SEA

MEDITERRANEAN

 SEA

Source: U.S. National Park Service

Sirhan Area

East

Safawi

Area 

Risha

Area

EXPLANATION

Study area

Sirhan Area Jordan Silurian Shale

Oil Assessment Unit

East Safawi Area Jordan Silurian

Shale Oil Assessment Unit

Risha Area Jordan Silurian Shale

Gas Assessment Unit

International boundary

0 30 60 90 120 KILOMETERS

0 30 60 90 120 MILES
ISSN 2327-6932 (online)

ISSN 2327-6916 (print)

http://dx.doi.org/10.3133/fs20143082

less of an effect on gas retention in the source rock compared to 

the previous areas.

The assessment input data for each unconventional AU are 

shown in table 1. Assessment unit probabilities are shown in table 2.

Resource Summary

The USGS quantitatively assessed unconventional shale-oil 

and shale-gas resources in three assessment units within Jordan 

(table 2). For unconventional resources, the mean totals are: 11 

million barrels of shale oil (MMBO), with a range from 0 to 

45 MMBO; 320 billion cubic feet of shale gas (BCFG), with a 

range from 0 to 917 BCFG; and 25 million barrels of natural gas 

liquids (MMBNGL), with a range from 0 to 79 MMBNGL.

Of the mean total shale-oil resource of 11 MMBO, 8 MMBO 

are estimated to be in the Sirhan Area Jordan Silurian Shale Oil 

AU, and 3 MMBO are estimated in the East Safawi Area Jordan 

Silurian Shale Oil AU. Nearly all potential shale-gas resources 

are in the Risha Area Jordan Silurian Shale Gas AU (mean of 312 

BCFG, with a range from 0 to 885 BCFG). The ranges of resource 

estimates reflect the high geologic uncertainty on the retention of 

oil and gas in the Jordanian Silurian source rock-reservoir system.

For Further Information

Assessment results are available at the USGS Energy 

Resources Program website, http://energy.usgs.gov/oilgas/. 

References Cited

Charpentier, R.R., and Cook, T.A., 2011, USGS methodology 

for assessing continuous petroleum resources: U.S. Geological 

Survey Open-File Report 2011–1167, 75 p., http://pubs.usgs.

gov/of/2011/1167/. 

Pitman, J.K., Schenk, C.J., Brownfield, M.E., Charpentier, R.R., 

Cook, T.A., Klett, T.R., Pollastro, R.M., 2012, Assessment 

of undiscovered conventional oil and gas resources of 

the Arabian Peninsula and Zagros Fold Belt, 2012: U.S. 

Geological Survey Fact Sheet 2012–3115, 4 p., http://pubs.

usgs.gov/fs/2012/3115/. 

Skarpnes, Oddvar, and Hagen, Sveinung, 2008, Sirhan Block 

evaluation, Jordan—Evaluation Report: Stavanger, Norway, 

Statoil, 89 p.

Table 1. Key assessment input data for unconventional assessment units in Jordan.

[EUR (estimated ultimate recovery per well), well drainage area, and success ratios are from U.S. shale-gas and shale-oil analogs. MMBO, million barrels of oil; 

BCFG, billion cubic feet of gas; AU, assessment unit. The average EUR input is the minimum, median, maximum, and calculated mean.]

Assessment input data

Sirhan Area Jordan Silurian Shale Oil AU East Safawi Area Jordan Silurian Shale Oil AU

Minimum Mode Maximum Calculated 

mean

Minimum Mode Maximum Calculated 

mean

Potential production area of AU (acres) 0 29,000 290,000 106,333 0 86,000 860,000 315,333

Average drainage area of wells (acres) 80 160 220 153 80 160 220 153

Success ratios (%) 10 40 70 40 10 40 70 40

Average EUR (MMBO, oil; BCFG, gas) 0.01 0.03 0.1 0.034 0.01 0.03 0.1 0.034

Risha Area Jordan Silurian Shale Gas AU

Minimum Mode Maximum Calculated 

mean

Potential production area of AU (acres) 0 276,000 1,105,000 460,333

Average drainage area of wells (acres) 120 160 200 160

Success ratios (%) 10 50 90 50

Average EUR (MMBO, oil; BCFG, gas) 0.1 0.2 1 0.24

Table 2. Jordan shale-oil and shale-gas resource assessment results.

[MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids; TPS, total petroleum system; AUs, assessment units. 

Results shown are fully risked estimates. For gas accumulations, all liquids are included under the NGL (natural gas liquids) category. 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. Shading indicates not applicable.]

Total Petroleum System 

(TPS) 

and Assessment Units (AUs)

AU

Probability

Accumulation 

Type

Total Undiscovered Resources

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

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

Silurian TPS

Sirhan Area Jordan Silurian

Shale Oil AU (20260161) 0.9 Oil 0 6 24 8 0 4 18 6 0 0 0 0

East Safawi Area Jordan Silurian

Shale Oil AU (20290161) 0.1 Oil 0 0 21 3 0 0 14 2 0 0 0 0

Risha Area Jordan Silurian

Shale Gas AU (20290162) 0.9 Gas 0 235 885 312 0 17 79 25

Total unconventional resources 0 6 45 11 0 239 917 320 0 17 79 25

Jordan Assessment Team

Christopher J. Schenk, Janet K. Pitman, 

Ronald R. Charpentier, Timothy R. Klett, 

Marilyn E. Tennyson, Tracey J. Mercier, 

Philip H. Nelson, Michael E. Brownfield, 

Mark J. Pawlewicz, and Craig J. Wandrey.