U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3090

December 2016 Printed on recycled paper

National and Global Petroleum Assessment

Assessment of Continuous Oil and Gas Resources 

of the South Sumatra Basin Province, Indonesia, 2016

Introduction

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable continuous oil and 

gas resources within the South Sumatra Basin Province (fig. 1), 

one of a series of backarc basins associated with subduction along 

the western margin of Sumatra, Indonesia. The Sumatra backarc realm underwent extension and rifting in the Eocene to early 

Oligocene that formed a series of horsts and grabens (Pulunggono, 

1986; Ginger and Fielding, 2005). The grabens were filled with 

typical synrift nonmarine facies, including fluvial, deltaic, marginal lacustrine sandstones, and shallow to deep water lacustrine 

shales. The thickest petroleum source rocks are found within the 

graben system. One of the petroleum source rocks in the South 

Sumatra Basin Province is within the synrift Eocene-Oligocene 

Lemat Formation, which includes organic-rich lacustrine shale of 

the Benakat member (Rashid and others, 1998; Bianchi and others, 

2007). Following cessation of rifting, regional thermal relaxation 

led to a sag phase with increased accommodation space and deposition. Petroleum source rocks reached thermal maturity for oil and 

gas generation beginning in the Miocene (Sarjono and Sardjito, 

1989; Reksalegora and Riadinjo, 2013). Compression from middle 

Miocene to Pliocene related to subduction dynamics resulted in 

numerous structures within the basin, many of which formed traps 

for conventional oil and gas accumulations.

For this assessment, a continuous source-reservoir rock 

system contains (1) greater than 2 weight percent total organic carbon, (2) the proper thermal maturity window for oil or gas generation, (3) greater than 15 meters of organic-rich shale, and (4) Type I 

or Type II organic matter. The assessment unit (AU) areas outlined 

in figure 1 represent continuous oil- and gas-prone areas that are 

interpreted to satisfy these geologic criteria. The range of uncertainty on assessment unit areas (table 1) reflects uncertainty on the 

extent and thickness of source-rock facies within the grabens and 

the extent and level of thermal maturation of the source rock.

Total Petroleum System and Assessment Units

For the South Sumatra Basin Province, the USGS defined 

the Lemat Lacustrine Total Petroleum System (TPS). The Lemat 

Lacustrine Shale Oil AU and the Lemat Lacustrine Shale Gas AU 

define the boundary of this TPS (fig. 1). The AU boundaries were 

developed from published maps depicting structure, facies, and 

thermal maturity (Ginger and Fielding, 2005; Rudd and others, 

2013). The geologic model proposed in this study is for oil and gas 

to have been generated within the Lemat Formation source rock in 

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable 

mean resources of 689 million barrels of continuous shale oil and 3.9 trillion cubic feet of shale gas in the South Sumatra Basin 

Province in Indonesia.

Figure 1. Map showing the location of the South Sumatra Basin, Indonesia, 

and the two continuous assessment units (AUs) defined in this study.

the graben system and for some portion of the oil and gas to have been 

retained in the source rock following petroleum migration. Retention 

represents the major source of geologic risk in this assessment.

Assessment input data for each assessment unit are shown in 

table 1. Well drainage areas, estimated ultimate recoveries, and success 

ratios were guided by U.S. shale-oil and shale-gas analogs, including 

the lacustrine petroleum system of the Eocene Green River Formation 

in the Uinta Basin, Utah (Johnson and others, 2015).

)

SUMATRA

Palembang

105°

0°

–5°

INDIAN 

OCEAN

0 25 50 MILES

0 25 50 KILOMETERS

EXPLANATION

Lemat Lacustrine Shale Gas AU

South Sumatra Basin Province boundary

Lemat Lacustrine Shale Oil AU

Source: U.S. Department of the Interior National Park Service

Barisan Mountains

SUMATRAN FAULT

MALAYSIA

INDONESIA

Sumatra

Java

Kalimantan

Borneo

Sulawesi

INDIAN

OCEAN

SOUTH

CHINA

SEA

SINGAPORE

Area

of study
ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20163090

Undiscovered Resources Summary

The USGS quantitatively assessed 

undiscovered continuous oil and gas 

resources within the South Sumatra Basin 

Province (table 2) of 689 million barrels of 

continuous shale oil with an F95–F5 range 

from 142 million barrels of oil (MMBO) 

to 1,581 MMBO; 3,886 billion cubic feet 

of (shale) gas (BCFG), or 3.9 trillion cubic 

feet of gas, with an F95–F5 range from 

793 to 9,062 BCFG; and 88 million barrels 

of natural gas liquids (MMBNGL) with an 

F95–F5 range from 16 to 213 MMBNGL.

For the Lemat Lacustrine Shale Oil 

AU, the estimated mean resources are 

689 MMBO with an F95–F5 range from 

142 to 1,581 MMBO, 2,069 BCFG of 

associated gas with an F95–F5 range from 

403 to 4,950 BCFG, and 41 MMBNGL 

with an F95–F5 range from 7 to 

102 MMBNGL.

For the Lemat Lacustrine Shale Gas 

AU, the estimated mean resources are 

1,817 BCFG with an F95–F5 range from 

390 to 4,112 BCFG and 47 MMBNGL with 

an F95–F5 range from 9 to 111 MMBNGL. 

The major source of geologic risk for the 

presence of recoverable continuous oil and 

gas resources is the retention of oil or gas in 

the source rock following migration, which 

may be related to Neogene compression 

and structural inversion.

Assessment input data—Continuous AUs

Lemat Lacustrine Shale Oil AU Lemat Lacustrine Shale Gas AU

Minimum Mode Maximum Calculated

mean Minimum Mode Maximum Calculatedmean

Potential production area of AU (acres) 1,000 1,805,000 5,471,000 2,425,667 1,000 1,111,000 3,000,000 1,370,667

Average drainage area of wells (acres) 80 160 220 153 80 120 160 120

Success ratios (%) 10 50 90 50 10 50 90 50

Average EUR (MMBO, oil; BCFG, gas) 0.04 0.08 0.2 0.086 0.1 0.3 0.7 0.319

AU probability 1.0 1.0

Table 1. Key assessment input data for two continuous assessment units in the South Sumatra Basin Province, Indonesia.

[AU, assessment unit; %, percent; EUR, estimated ultimate recovery per well; MMBO, million barrels of oil; BCFG, billion cubic feet of gas. EUR, well drainage area, 

and success ratios are from U.S. shale-oil and shale-gas analogs. The average EUR input is the minimum, median, maximum, and calculated mean. Shading indicates 

not applicable]

Total petroleum system 

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

Lemat Lacustrine Total Petroleum System

Lemat Lacustrine Shale Oil AU 1.0 Oil 142 585 1,581 689 403 1,719 4,950 2,069 7 34 102 41

Lemat Lacustrine Shale Gas AU 1.0 Gas 390 1,563 4,112 1,817 9 40 111 47

Total undiscovered resources 142 585 1,581 689 793 3,282 9,062 3,886 16 74 213 88

Table 2. Assessment results for two continuous assessment units in the South Sumatra Basin Province, Indonesia.

[MMBO, million barrels of oil; BCFG, billions of cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For gas 

accumulations, all liquids are included within 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 the assumption of perfect positive correlation. Shading indicates not applicable]

References Cited

Bianchi, N., Barres, E., Argakoesoemah, R.M.I., Syafri, C., and Kamal, A., 2007, Managing uncertainty of petroleum system components in basin modelling 

studies—An example from the South Sumatra Basin, Indonesia, in Thirty-First Annual Convention and Exhibition, Jakarta, Indonesia, May, 2007, Proceedings: Indonesian Petroleum Association, Paper IPA07–G–135, 15 p.

Ginger, David, and Fielding, Kevin, 2005, The petroleum systems and future potential of the South Sumatra Basin, in Thirtieth Annual Convention and Exhibition, Jakarta, Indonesia, August, 2005, Proceedings: Indonesian Petroleum Association, Paper IPAO5–G–039, p. 67–89.

Johnson, R.C., Birdwell, J.E., Mercier, T.J., Brownfield, M.E., Charpentier, R.R., Klett, T.R., Leathers, H.M., Schenk, C.J., and Tennyson, M.E., 2015, Assessment of undiscovered oil and gas resources in the Uteland Butte Member of the Eocene Green River Formation, Uinta Basin, Utah: U.S. Geological Survey 

Fact Sheet 2015–3052, 2 p. [Available at http://dx.doi.org/10.3133/fs20153052.]

Pulunggono, A., 1986, Tertiary structural features related to extensional and compressive tectonics in the Palembang Basin, South Sumatra, in Fifteenth Annual 

Convention and Exhibition, Jakarta, Indonesia, October, 1986, Proceedings: Indonesian Petroleum Association, p. 187–213.

Rashid, Harmen, Sosrowidjojo, I.B., and Widiarto, F.X., 1998, Musi Platform and Palembang High—A new look at the petroleum system, in Twenty-Sixth 

Annual Convention and Exhibition, Jakarta, Indonesia, May, 1998, Proceedings: Indonesian Petroleum Association, Paper IPA98–1–107, p. 265–276.

Reksalegora, S.W., and Riadini, Putri, 2013, Critical parameters in basin modeling of Bungamas PSC, South Sumatra Basin, in Thirty-Seventh Annual Convention and Exhibition, Jakarta, Indonesia, May, 2013, Proceedings: Indonesian Petroleum Association, Paper IPA13–G–109, 15 p.

Rudd, R.A., Tulot, Suraya, and Siahaan, Darius, 2013, Rejuvenating play-based exploration concept in South Sumatra Basin, in Thirty-Seventh Annual Convention and Exhibition, Jakarta, Indonesia, May, 2013, Proceedings: Indonesian Petroleum Association, Paper IPA13–G–068, 14 p.

Sarjono, Sumuyut, and Sardjito, 1989, Hydrocarbon source rock identification in the South Palembang Sub-basin, in Eighteenth Annual Convention and 

Exhibition, Jakarta, Indonesia, October, 1989: Indonesian Petroleum Association, Paper IPA–89–13.08, p. 427–467.

South Sumatra Basin Assessment Team

Christopher J. Schenk, Marilyn E. Tennyson, Timothy R. Klett, Thomas M. Finn, Tracey J. Mercier, Stephanie B. Gaswirth, 

Kristen R. Marra, Phuong A. Le, and Sarah J. Hawkins

For More Information

Assessment results are available at the USGS Energy Resources Program Web site at http://energy.usgs.gov.