Assessment of Undiscovered Oil and Gas Resources of Southeast Asia, 2010

World Petroleum Resources Assessment Project

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 21.6 billion barrels of oil and a mean of 299 trillion cubic feet of undiscovered natural gas in 23 provinces of southeast Asia.

Introduction

The U.S. Geological Survey (USGS) assessed the potential for undiscovered conventional oil and gas fields within geologic provinces of southeast Asia as part of the USGS World Petroleum Resources Assessment Project (fig. 1). Twenty-three provinces were assessed in this study (table 1), including provinces entirely or partially within Thailand, Laos, Cambodia, Vietnam, Myanmar, Malaysia, Indonesia, Brunei, China, and Philippines. Many of the oil and gas basins within these geologic provinces originated as extensional basins that evolved into a post-rift thermal subsidence phase, which is characterized by carbonate platform deposits or prograding clastic wedges typical of passive margins. This simple sketch does not reflect the complexity of the tectonic history in southeast Asia, which has included rifting and attenuation of continental crust, opening and closing of ocean basins, development of regional fault systems and associated structures, collision and suturing of terranes, formation of accretionary prisms and local uplifts (Morley, 2001, 2002; Hutchinson, 2004; Hall and others, 2008). Petroleum systems in provinces of southeast Asia reflect the complex tectonic evolution, but generalities can be made concerning the origin of oil and gas in what are mainly Cenozoic basins (Todd and others, 1997; Doust and Sumner, 2007; Hall, 2009). Petroleum source rocks mainly are synrift deep-basin lacustrine and marginal lacustrine shales; post-rift marginal marine to marine coaly mudstones, coals, and marine shales (Todd and others, 1997). Oil predominantly is generated from synrift lacustrine shales, whereas gas is generated from the post-rift coaly mudstones, coals, and shales, and by cracking of earlier-formed oil. As gas generation I N D O N E S I A

Figure 1. Locations of 23 provinces of southeast Asia assessed in this study.

[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). 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. Largest expected oil field size in MMBO; gas field size is in BCFG]

Total Petroleum Systems (TPS) and Assessment Units (AU)

Pearl River Mouth Basin Province (Paleogene Lacustrine TPS)

Song Hong Basin Province (Eocene-Miocene Composite TPS)

Paleogene-Neogene Reservoirs AU Phu Khanh Basin Province (Paleogene TPS) Paleogene-Neogene Reservoirs AU Khorat Plateau Province (Mesozoic TPS)

Khorat Group Sandstones AU Cuu Long Basin Province (Eocene-Oligocene Composite TPS)

Nam Con Son Basin Province (Eocene-Miocene Composite TPS)

Oligocene-Miocene Reservoirs AU South China Sea Platform (Miocene TPS) Dangerous Grounds-Reed Bank AU Thai Basin Province (Eocene-Miocene Composite TPS)

Offshore Western Cenozoic Rifts AU Thai Cenozoic Basins Province (Eocene-Miocene Composite TPS)

Onshore Cenozoic Rifts AU

Palawan Shelf Province (Eocene-Miocene Composite TPS)

Eocene-Miocene Reservoirs AU Tarakan Basin (Neogene TPS)

Mangkalihat Carbonates AU Sulu Sea Province (Miocene TPS)

Baram Delta/Brunei-Sabah Basin Province (Brunei-Sabah TPS)

Brunei-Sabah Turbidites AU AU Largest Field probexpected type ability field size

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas F95

1,766 1,352 Oil (MMBO) F50 F5 Mean

3,643 Total Undiscovered Resources Gas (BCFG) F95 F50

1,208 2,165 2,905 5,130 4,866 9,900 18,563 10,581 3,384 7,515 15,100 F5 Mean

8,159 NGL (MMBNGL) F95 F50 F5 Mean

[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). 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. Largest expected oil field size in MMBO; gas field size is in BCFG]

Total Petroleum Systems (TPS) and Assessment Units (AU)

Greater Sarawak Basin Province (Sarawak Basin TPS)

East Natuna Carbonate AU

Malay Basin Province (Oligocene-Miocene Composite TPS)

Main Malay-Tho Chu AU

Barito Basin (Eocene-Miocene Composite TPS)

Barito Foredeep Structures AU

Pematang/Sihapas Siliciclastics AU East Java Basin (Eocene-Miocene Composite TPS)

East Java Carbonates AU

East Java Siliciclastics AU

Kutei Basin Deltaics AU

Kutei Basin Turbidites AU

North Sumatra Basin (Bampo-Cenozoic TPS)

Northwest Java Basin (Eocene-Miocene Composite TPS)

Penyu-West Natuna Basin Province (Oligocene-Miocene Composite TPS)

Gabus-Udang-Urang Sandstones AU South Sumatra Basin (Lahat/Talang Akar-Cenozoic TPS)

Total Conventional Resources AU Largest Field probexpected type ability field size

Oil 1.0 Gas Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas Oil 1.0 Gas Oil 1.0 Gas

Oil 1.0 Gas – 2,492

8,922 19,541 41,558 21,632 128,908 272,848 557,051 298,761 Oil (MMBO) F50 F5 Mean

3,047 Total Undiscovered Resources

1,398 Gas (BCFG) F50 F5 Mean

1,338 2,967 3,112 6,194 NGL (MMBNGL) F95

8,270 17,216 F5 Mean

is later than oil, gas is focused into the younger, post-rift clastic and carbonate reservoirs. Volumetrically, gas would be expected to be more prevalent than oil in these provinces where post-rift sources have achieved the appropriate thermal maturity for generation (Doust and Sumner, 2007). The methodology for the assessment included a complete geologic framework description for each province mainly based on published literature and definition of petroleum systems and assessment units within these systems. Exploration and discovery history was a critical part of the methodology used to estimate sizes and numbers of undiscovered accumulations. In areas where there are no discoveries (for example, Phu Khanh Basin) geologic analogs were used as a basis for volumes of undiscovered oil and gas resources. Each assessment unit was assessed for undiscovered oil and nonassociated gas accumulations, and coproduct ratios were used to calculate the volumes of associated gas (gas in oil fields) and natural gas liquids.

Resource Summary

The USGS assessed undiscovered conventional oil and gas resources in assessment units within 23 geologic provinces (table 1). For conventional oil resources, the mean total is 21,632 million barrels of oil (MMBO), with a range from 8,922 to 41,558 MMBO; for undiscovered conventional gas the mean total is 298,761 billion cubic feet (BCFG), with a range from 128,908 BCFG to 557,051 BCFG; and a mean total of 9,099 million barrels of natural gas liquids (MMBNGL), with a range from 3,828 to 17,216 MMBNGL. Of the mean oil total of 21,632 MMBO, about 70 percent is estimated to be in six provinces—Baram Delta/Brunei-Sabah Basin (mean of 4,278 MMBO), Kutei Basin (mean of 3,215 MMBO), South China Sea Platform (mean of 2,522 MMBO), East Java Basin (mean of 2,036 MMBO), Cuu Long Basin (mean of 1,735 MMBO), and Thai Basin (mean of 1,212 MMBO). In addition, several provinces are estimated to have potential oil volumes greater than 500 MMBO—Northwest Java Basin (mean of 726 MMBO), Tarakan Basin (mean of 707 MMBO), Nam Con Son Basin (mean of 685 MMBO), Malay Basin (mean of 664 MMBO), Greater Sarawak Basin (mean of 643 MMBO), and Pearl River Mouth Basin (mean of 608 MMBO). For the mean undiscovered gas total of 298,761 BCFG, about 60 percent is estimated to be in six provinces—Kutei Basin (mean of 46,001 BCFG), Greater Sarawak Basin (mean of 38,073 BCFG), East Java Basin (mean of 31,489 BCFG), Baram Delta/Brunei-Sabah Basin (mean of 26,375 BCFG), South China Sea Platform (mean of 25,519 BCFG), and Nam Con Son Basin (mean of 14,600 BCFG). Several other provinces are estimated to have potential gas volumes greater than 10,000 BCFG—Thai Basin (mean of 14,583 BCFG), Phu Khanh Basin (mean of 13,040 BCFG), Tarakan Basin (mean of 12,675 BCFG), Song Hong Basin (mean of 12,266 BCFG), and Malay Basin (mean of 12,088 BCFG). Overall, the assessment indicates that (1) more than 90 percent of the undiscovered oil and gas resources are offshore, and (2) there is more than twice as much undiscovered gas resource (298,761 BCFG, or 49,794 MMBOE) than undiscovered oil resource (21,632 MMBO) in the provinces of southeast Asia using a barrels of oil equivalent conversion.

References

Doust, H., and Sumner, H.S., 2007, Petroleum systems in rift basins—a collective approach in southeast Asia basins: Petroleum Geoscience, v. 13, p. 127–144.

Hall, R., 2009, Hydrocarbon basins in SE Asia: understanding why they are there: Petroleum Geoscience, v. 15, p. 131–146.

Hall, R., van Hattum, M.W.A., and Spakman, Wim, 2008, Impact of India— Asia collision on SE Asia: the record in Borneo: Tectonophysics, v. 451, p. 366–389.

Hutchinson, C.S., 2004, Marginal basin evolution: the southern South China Sea: Marine and Petroleum Geology, v. 21, p. 1129–1148.

Morley, C.K., 2001, Combined escape tectonics and subduction roll-backbackarc extension: a model for the Tertiary rift basins in Thailand, Malaysia, and Laos: Journal of Geological Society of London, v. 158, p. 461–474.

Morley, C.K., 2002, A tectonic model for the Tertiary evolution of strike-slip faults and rift basins in SE Asia: Tectonophysics, v. 347, p. 89–215.

Todd, S.P., Dunn, M.E., and Barwise, A.J.G., 1997, Characterizing petroleum charge systems in the Tertiary of SE Asia, in Fraser, A.J., Matthews, S.J., and Murphy, R.W., eds., Petroleum geology of Southeast Asia: Geological Society of London Special Publication v. 126, p. 25–47.

For Further Information

Supporting studies of the geologic models and the methodology used in the assessment of Southeast Asia Basins are in progress. Assessment results are available at the USGS Energy Program website, http://energy.cr.usgs.gov/oilgas/.

Southeast Asia Provinces Assessment Team:

Christopher J. Schenk (Task Leader; schenk@usgs.gov), Michael E. Brownfield, Ronald R. Charpentier, Troy A. Cook, Timothy R. Klett, Mark A. Kirschbaum, Janet K. Pitman, and Richard M. Pollastro.

Where this page came from

This page was imported from U.S. Geological Survey. Published by the U.S. Geological Survey and, as a work of the United States government, in the public domain.

Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.