U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2017–3086

February 2018

National and Global Petroleum Assessment

Assessment of Undiscovered Continuous Oil and Gas Resources in 

the Hanoi Trough, Vietnam, 2017

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable continuous resources of 52 million barrels of oil and 591 billion cubic feet of gas in the Hanoi Trough of Vietnam.

Introduction

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

the potential for undiscovered, technically recoverable continuous 

oil and gas resources in the Hanoi Trough of Vietnam (fig. 1). The 

Hanoi Trough represents the onshore part of the Song Hong Basin 

(Nielsen and others, 1999; Hiep, 2015; Lei and others, 2015). The 

structural evolution of the Hanoi Trough is linked to the dynamics of the regional Red River fault zone, which can be traced from 

Tibet eastward more than 1,000 kilometers to the Hanoi Trough 

and into the Gulf of Tonkin. From the late Eocene through the early 

Miocene, the Red River fault zone was a transtensional, left-lateral 

fault that divided into several strands, forming several horsts and 

grabens that define the Hanoi Trough (Rangin and others, 1995; 

Hiep, 2015). In the middle Miocene, coincident with cessation of 

seafloor spreading in the South China Sea, the movement on the 

Red River fault changed to transpressional with minor inversion 

and uplift in the Hanoi Trough. Since the end of the Miocene, the 

Red River fault has been a dextral fault with little or no movement. 

Within the grabens of the Hanoi Trough, sediments can be as much 

as 6 kilometers thick. The latest Eocene to early Oligocene synrift 

sediments are predominantly fluvial to marginal lacustrine conglomerates and sandstones and deep-water, organic-rich lacustrine 

shales. From the late Oligocene to Miocene, the grabens filled with 

fluvial, deltaic, and estuarine clastics with intercalated coals and 

lignites (Nielsen and others, 1999; Wysocka and Świerczewska, 

2005). The principal petroleum source rocks in the Hanoi Trough 

are late Eocene–early Oligocene, organic-rich lacustrine shales and 

Neogene coals and lignites.

Total Petroleum Systems and Assessment Units

The USGS defined a Hanoi Trough Oligocene Lacustrine 

Total Petroleum System (TPS) with the Hanoi Trough Oligocene 

Lacustrine Shale Oil Assessment Unit (AU) and the Hanoi Trough 

Oligocene Lacustrine Shale Gas AU, based on mapping by Hiep 

(2015). Organic-rich lacustrine shales in rift basins in northern 

Vietnam are up to 500 meters thick, and the organic matter is 

predominantly Type I with lesser amounts of Type III. Total organic 

carbon contents are up to 8 weight percent (Nielsen and others, 

1999, 2007; Petersen and others, 2001). Lacustrine source rocks 

in the AU are interpreted to be within the thermal window for oil 

generation, although a small area is in the thermal gas generation 

window (Hiep, 2015). The geologic model is for oil and gas to have 

been generated from these Oligocene lacustrine shales and for some 

portion of the oil and gas to have been retained within the shales 

following migration. The Hanoi Trough Neogene Coalbed Gas TPS 

and the Hanoi Trough Neogene Coalbed Gas AU were defined in 

this study for potential biogenic gas to have been generated and 

retained within the shallow, thermally immature coals and lignites.

The assessment input data are summarized in table 1. Input 

data for well-drainage areas, success ratios, and estimated ultimate 

recoveries are derived from analog shale-oil, shale-gas, and coalbedgas assessment units in the United States.

Undiscovered Resources Summary

The USGS quantitatively assessed undiscovered continuous 

oil and gas resources in three AUs in the Hanoi Trough of Vietnam 

(table 2). The estimated mean total for continuous oil resources 

is 52 million barrels of oil (MMBO) with an F95–F5 range from 

0 to 127 MMBO. The estimated mean total for continuous gas is 

591 billion cubic feet of gas (BCFG) with an F95–F5 range from 

147 to 1,210 BCFG. 

Figure 1. Map showing the location of three continuous assessment 

units (AUs) in the Hanoi Trough of Vietnam.

21°

106° 107°

20°

HANOI

Haiphong

Thanh Hòa

VIETNAM

GULF OF TONKIN

Song Hong

Basin

Hanoi 

Trough

Base map from U.S. Department of the Interior National Park Service

SOUTH

CHINA

SEA

CHINA

LAOS

THAILAND

CAMBODIA

Map

area

GULF OF

 TONKIN

VIETNAM

EXPLANATION

Hanoi Trough Oligocene Lacustrine Shale Oil AU

Hanoi Trough Neogene Coalbed Gas AU

Hanoi Trough Oligocene Lacustrine Shale Gas AU

Red River fault zone—Dashed where unknown

0 100 200 KILOMETERS

0 100 200 MILES
ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20173086

Hanoi Trough Assessment Team

Christopher J. Schenk, Marilyn E. Tennyson, Tracey J. Mercier, Cheryl A. Woodall, Phuong A. Le, Timothy R. Klett, Thomas M. Finn, 

Heidi M. Leathers-Miller, Stephanie B. Gaswirth, and Kristen R. Marra

For More Information

Assessment results are also available at the USGS Energy Resources Program website at https://energy.usgs.gov.

Assessment input data—Continuous AUs

Hanoi Trough Oligocene Lacustrine Shale Oil AU Hanoi Trough Oligocene Lacustrine Shale Gas AU

Minimum Mode Maximum Calculated

mean Minimum Mode Maximum Calculatedmean

Potential production area of AU (acres) 800 155,000 310,000 155,267 800 17,174 34,348 17,441

Average drainage area of wells (acres) 40 120 200 120 80 120 160 120

Success ratio (%) 10 50 90 50 10 50 90 50

Average EUR (MMBO, oil; BCFG, gas) 0.04 0.08 0.2 0.086 0.1 0.25 0.7 0.273

AU probability 0.9 0.9

Assessment input data—Continuous AU

Hanoi Trough Neogene Coalbed Gas AU

Minimum Mode Maximum Calculated

mean

Potential production area of AU (acres) 800 426,500 853,000 426,767

Average drainage area of wells (acres) 40 80 120 80

Success ratio (%) 40 60 80 60

Average EUR (BCFG) 0.08 0.2 0.4 0.215

AU probability 1.0

Total petroleum systems 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

Hanoi Trough Oligocene Lacustrine Total Petroleum System

Hanoi Trough Oligocene Lacustrine Shale Oil AU 0.9 Oil 0 46 127 52 0 36 106 42 0 0 1 0

Hanoi Trough Oligocene Lacustrine Shale Gas AU 0.9 Gas 0 16 43 18 0 0 1 0

Hanoi Trough Neogene Coalbed Gas Total Petroleum System

Hanoi Trough Neogene Coalbed Gas AU 1.0 Gas 147 488 1,061 531 0 0 0 0

Total undiscovered continuous resources 0 46 127 52 147 540 1,210 591 0 0 2 0

Table 2. Assessment results for three continuous assessment units in the Hanoi Trough of Vietnam.

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

risked estimates. For gas accumulations, all liquids are included in the NGL 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]

Table 1. Key assessment input data for three continuous assessment units in the Hanoi Trough of Vietnam.

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

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

indicates not applicable]

References Cited

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potential: Coordinating Committee for Geoscience Programmes 

in East and Southeast Asia (CCOP) Workshop on Unconventional Oil and Gas Resources, Daejeon, Korea, June 8–12, 2015, 

37 p., accessed June 10, 2017, at http://ccop.asia/uc/data/41/docs/

Vietnam-CountryReport_Vietnam_presentation.pdf.

Lei Chao; Ren Jianye; Sternai, Pietro; Fox, Matthew; Willett, Sean; 

Xie Xinong; Clift, P.D.; Liao Jihua; and Wang Zhengfeng, 2015, 

Structure and sediment budget of Yinggehai–Song Hong Basin, 

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basin reorganization in Southeast Asia: Tectonophysics, v. 655, 

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Nielsen, L.H.; Mathiesen, Anders; Bidstrup, Torben; Vejbæk, 

O.V.; Dien, P.T; and Tiem, P.V., 1999, Modeling of hydrocarbon 

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