World Petroleum Resources Project

Assessment of Undiscovered Conventional Oil and Gas 

Resources of Six Geologic Provinces of China, 2011

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

mean volumes of undiscovered conventional petroleum resources in six geologic provinces 

of China at 14.9 billion barrels of oil, 87.6 trillion cubic feet of natural gas, and 1.4 billion 

barrels of natural-gas liquids.

Introduction

The U.S. Geological Survey (USGS) assessed 

the potential for undiscovered conventional oil and 

gas resources in six geologic provinces of China: 

Junggar Basin, Bohaiwan Basin, Ordos Basin, 

Sichuan Basin, Songliao Basin, and Tarim Basin 

(fig. 1). Each province was divided into 1–4 assessment units (AU), for a total of 13 AUs (table 1).

East

China

Sea

Bay of

Bengal

Sea of

Japan

South

China

Sea

INDIA

RUSSIA

NORTH

KOREA

SOUTH

KOREA

JAPAN

MONGOLIA

KAZAKHSTAN

KYRGYSTAN

TAJIKISTAN

CHINA

BANGLADESH

MYANMAR

VIETNAM

LAOS

THAILAND

PHILIPPINES

PAKISTAN

AFGHANISTAN

NEPAL

60° 70° 80° 90° 100° 110° 120° 130° 140°

50°

40°

30°

20°

0 500 KILOMETERS

0 500 MILES

Junggar

Basin

Songliao

Basin

Ordos

Basin

Sichuan

Basin

Bohaiwan

 Basin

Tarim Basin

Cambodia

CHINA

RUSSIA

INDIA

Figure 1. Locations of six geologic provinces assessed in this study.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3117

September 2012
Only conventional oil and gas potential was 

assessed. Continuous (unconventional) resources 

such as shale gas, coalbed gas, and tight gas sands 

may exist in some of these basins but were not 

assessed at this time.

The assessment methodology included a study 

of the petroleum systems in each province, including 

tectonics, source rocks, reservoirs, and other geologic 

characteristics relevant to petroleum generation, 

migration, and trapping. The characteristics of discovered fields and their exploration histories were 

also studied. Estimates of the numbers and sizes of 

undiscovered oil fields were made separately from 

the estimates for gas fields. Coproduct ratios were 

applied to make additional estimates of gas and 

natural gas liquids (NGL) in oil fields and liquids 

in gas fields.

[AU, assessment unit; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids; MMBO, millions barrels of oil; NGL natural gas liquids. Results shown are fully risked

estimates. For gas fields, all liquids are included as NGL. Expected largest oil field size in MMBO; expected largest gas field size in BCFG. 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] 

Total petroleum systems

(TPS)

and assessment units (AU) 

AU

probability

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

Junggar Basin

Pre-Jurassic Reservoirs AU 1.0

Oil 149 364 772 1,516 833 109 255 563 285 4 10 25 12

Gas 350 209 569 1,734 716 5 15 47 19

Jurassic-Tertiary Reservoirs AU 1.0

Oil 192 748 1,488 2,786 1,590 585 1,328 2,871 1,476 15 36 78 40

Gas 664 1,037 2,309 4,851 2,544 30 75 181 86

Bohaiwan Basin

Tertiary Lacustrine and Buried

Hills AU 1.0

Oil 248 1,493 2,577 4,341 2,699 503 888 1,522 933 8 15 28 16

Gas 1,478 1,680 4,168 9,838 4,748 24 67 205 86

Ordos Basin

Ordovician Gas AU 1.0

Oil 0 0 0 0 0 0 0 0 0 0 0 0

Gas 290 3,048 5,612 10,254 5,993 81 150 274 160

Triassic-Jurassic Fluvial and

Lacustrine Sandstones AU 1.0

Oil 582 1,839 3,856 7,413 4,137 224 496 1,012 541 6 13 28 15

Gas 0 0 0 0 0 0 0 0

Sichuan Basin

Southeastern Fold Belt AU 1.0

Oil 0 0 0 0 0 0 0 0 0 0 0 0

Gas 2,040 9,919 18,125 31,274 19,040 12 23 42 25

Northwestern Depression and

Foldbelt AU 1.0

Oil 0 0 0 0 0 0 0 0 0 0 0 0

Gas 728 2,188 4,310 7,791 4,559 3 5 11 6

Central Uplift AU 1.0

Oil 26 55 111 210 119 52 117 254 130 1 3 8 4

Gas 1,711 1,092 3,334 10,231 4,176 28 87 276 111

Songliao Basin

Stratigraphic Traps AU 1.0

Oil 68 108 222 456 244 32 81 243 103 1 2 7 3

Gas 284 262 624 1,607 735 7 16 44 20

Anticlinal AU 1.0

Oil 51 33 89 268 111 8 29 136 46 0 1 4 1

Gas 203 71 233 963 335 2 2 26 9

Kailu Depression AU 1.0

Oil 29 10 38 150 53 2 12 73 22 0 0 2 1

Gas 99 19 71 410 125 0 2 11 3

Structural Traps AU 1.0

Oil 13 3 11 54 18 0 3 27 8 0 0 1 0

Gas 1,262 723 2,465 7,764 3,097 4 14 45 18

Tarim Basin

Conventional Reservoirs AU 1.0

Oil 324 2,327 4,737 9,332 5,141 2,507 5,450 11,097 5,954 109 260 596 295

Gas 6,525 11,283 28,973 63,040 32,036 150 420 1,058 489

Total conventional

 resources 6,980 13,901 26,526 14,945 35,553 79,452 167,555 87,602 490 1,216 2,997 1,419
Resource Summary

The Junggar Basin, in northwestern China, was 

divided into two AUs: one for the pre-Jurassic 

reservoirs and one for the Jurassic through Tertiary 

reservoirs. The Pre-Jurassic Reservoirs AU has oil 

and gas fields that are primarily in Permian and 

Triassic fluvial sandstones and fluvial and alluvial 

fan conglomerates. The main source rocks are Permian lacustrine rocks and Jurassic coals. The JurassicTertiary Reservoirs AU has Jurassic and Tertiary 

fluvial and nearshore lacustrine sandstone reservoirs. 

The main source rocks are also Jurassic coals and 

Permian lacustrine rocks. Traps for both AUs are 

mostly anticlines and fault blocks.

The Bohaiwan Basin was assessed as a single 

AU: the Tertiary Lacustrine and Buried Hills AU. 

Tertiary reservoir rocks are mostly fluvial, lacustrine 

deltaic, and lacustrine turbiditic sandstones. The reservoirs in the buried hills include fractured Archean 

crystalline basement rocks, karsted Proterozoic 

limestones and dolomites, Cambrian and Ordovician 

limestones, and Mesozoic volcanics. Source rocks 

are deep-water lacustrine shales and mudstones, most 

importantly those in the Eocene Shahejie Formation. 

The traps include structural and stratigraphic traps for 

the Tertiary reservoirs, as well as classic examples of 

buried hills.

The Ordos Basin was divided into two conventional AUs. The Ordovician Gas AU has gas fields 

producing from carbonates of the Ordovician Majiagou Formation that have significant karst development beneath a regional unconformity. Source rocks 

are primarily Upper Carboniferous and Permian coals 

and shales, but there may be some contribution from 

Ordovician carbonate sources. The Triassic-Jurassic 

Fluvial and Lacustrine Sandstones AU has reservoirs 

in Triassic and Jurassic fluvial and deltaic sandstones. 

The main source rock is lacustrine mudstones of 

the Triassic Yanchang Formation. Traps are mostly 

stratigraphic.

The Sichuan Basin was divided geographically 

into three AUs: one for gas fields in the heavily 

folded southeastern part of the basin (Southeastern 

Fold Belt AU), one for gas fields in the northwestern 

depression and foldbelt (Northwestern Depression 

and Foldbelt AU), and one for oil and gas fields in 

the central uplift (Central Uplift AU). Most of the 

fields are gas fields, with reservoirs ranging in age 

from Proterozoic to Jurassic. Most of the oil fields 

have Jurassic reservoirs. Reservoir rocks include 

Proterozoic and Carboniferous through Triassic carbonates, as well as Triassic and Jurassic sandstones. 

Source rocks are shales ranging from Cambrian to 

Jurassic in age. Traps include anticlines and buried 

hills.

The Songliao Basin was divided into four AUs. 

Oil and gas fields of the Stratigraphic Traps AU 

have Upper Cretaceous fluvial and deltaic sandstone 

reservoirs in stratigraphic traps, primarily sourced 

from Lower Cretaceous lacustrine rocks. The Anticlinal AU has similar reservoir and source rocks, but 

the traps are primarily structural and are located on 

the major anticlines in the center of the basin. The 

Kailu Depression AU, in the southwestern part of the 

basin, also has similar reservoir and source rocks; it 

contains both structural and stratigraphic traps. The 

Structural Traps AU has older sandstone reservoirs 

that are below the Cretaceous Qingshankou Formation and are sourced by the Jurassic coal beds. The 

Structural Traps AU has both structural and stratigraphic traps.

The Tarim Basin was assessed as a single AU: 

the Conventional Reservoirs AU. Reservoirs are 

mainly Jurassic and Miocene fluvial and lacustrine 

sandstones, along with some clastic and carbonate 

reservoirs of Ordovician and Carboniferous ages. 

Source rocks are primarily the Jurassic lacustrine 

shales and coals, but there may be some contribution 

from Ordovician marine rocks and Carboniferous 

coals. Traps are mostly anticlines and fault blocks.

For Further Information

Supporting studies, including documentation of 

the methodology used in the assessments, are available on the USGS Energy Program website, http://

energy.usgs.gov/.

China Assessment Team

Ronald R. Charpentier (charpentier@usgs.gov), 

Christopher J. Schenk, Michael E. Brownfield, Troy 

A. Cook, Timothy R. Klett, Janet K. Pitman, and 

Richard M. Pollastro. 
Great Wall of China at Badaling taken October 18, 2009 by Ronald R. Charpentier, U.S. Geological Survey.