U.S. Geological Survey–PetroBangla

Cooperative Assessment of Undiscovered

Natural Gas Resources of Bangladesh

By USGS-Bangladesh Gas Assessment Team

U.S. Geological Survey Bulletin 2208-A

U.S. Department of the Interior

U.S. Geological Survey

The Bangladesh gas resource assessment was conducted under the purview of the 

Participating Agency Service Agreement (PASA) signed between USAID and the U.S. 

Department of Energy (DOE)—PASA No. 388-P-00-99-00026. The 2-year agreement 

expires on August 19, 2001.

The PASA provides for assistance to the Natural Gas Sector pursuant to which the 

resource assessment was jointly carried out. PASA also envisages transfer of new 

technology, modeling practices, and geoscience theory from existing and established 

programs in the United States to the Government of Bangladesh, Petrobangla, and 

Bangladesh academia.

In preparation for the cooperative assessment effort, Bangladesh geoscientists 

received training and familiarization from the U.S. Geological Survey in world 

resource assessment methodology.

Petroleum Systems and Related Geologic 

Studies in Region 8, South Asia

Edited by Craig J. Wandrey
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Any use of trade, product, or fi rm names in this publication

is for descriptive purposes only and does not

imply endorsement by the U.S. Government

This publication is only available online at:

http://geology.cr.usgs.gov/pub/bulletins/b2208-a/

Posted online June 2001, version 1.0

Manuscript approved for publication June 18, 2001

Published in the Central Region, Denver, Colorado

Editing, layout, and photocomposition—Richard W. Scott, Jr.

Graphics by the authors
III

Contents

Part I—Overview .......................................................................................................................................... 1

Introduction .......................................................................................................................................... 1

Acknowledgments............................................................................................................................... 2

Assessment of Gas Resources of Bangladesh............................................................................... 2

General Geology ......................................................................................................................... 2

The Tertiary Composite Total Petroleum System................................................................... 2

Assessment Units ....................................................................................................................... 3

Part II—Assessment Unit Descriptions.................................................................................................... 6

Bang0101: Surma Basin Assessment Unit....................................................................................... 6

Bang0102: Eastern Extremely Folded Assessment Unit ................................................................ 6

Bang0103: High-Amplitude Faulted Anticlines Assessment Unit ................................................ 7

Bang0104: Moderately Folded Anticlines Assessment Unit......................................................... 7

Bang0105: Western Slope Assessment Unit ................................................................................... 8

Bang0106: Western Platform Assessment Unit .............................................................................. 8

Perspective of the Assessment.................................................................................................................. 9

References Cited .......................................................................................................................................... 9

Addendum 1................................................................................................................................................. 10

Assessment Results Summary ........................................................................................................ 10

Assessment Unit Bang0101, Surma Basin, Monte Carlo Results .............................................. 12

Assessment Unit Bang0102, Eastern Extremely Folded Belt, Monte Carlo Results ............... 20

Assessment Unit Bang0103, High-Amplitude Faulted Anticlines, Monte Carlo Results........ 32

Assessment Unit Bang0104, Moderatley Folded Anticlines, Monte Carlo Results ................ 40

Assessment Unit Bang0105, Western Slope, Monte Carlo Results........................................... 48

Assessment Unit Bang0106, Western Platform, Monte Carlo Results...................................... 60

Addendum 2................................................................................................................................................. 72

Assessment Unit Bang0101, Surma Basin, Seventh Approximation Data Form ..................... 72

Assessment Unit Bang0102, Eastern Extremely Folded Belt, Seventh 

Approximation Data Form ................................................................................................... 75

Assessment Unit Bang0103, High-Amplitude Faulted Anticlines, Seventh 

Approximation Data Form ................................................................................................... 78

Assessment Unit Bang0104, Moderately Folded Anticlines, Seventh 

Approximation Data Form ................................................................................................... 81

Assessment Unit Bang0105, Western Slope, Seventh Approximation Data Form.................. 84

Assessment Unit Bang0106, Western Platform, Seventh Approximation Data Form............. 87

Assessment Unit Bang0101, Surma Basin, Known Data............................................................. 90

Assessment Unit Bang0104, Moderately Folded Anticlines, Known Data............................. 105
IV

Contributors to This Report

Figures

 1. Generalized geologic map of Bangladesh and adjacent areas............................................ 3

 2. Estimates of undiscovered natural gas resources of Bangladesh ...................................... 4

Table

 1. Stratigraphic nomenclature of Ganges-Brahmaputra delta in 

eastern India and Bangladesh ................................................................................................... 5

USGS–Bangladesh Gas Assessment Team 

 PetroBangla USGS 

M. Ismail Thomas S. Ahlbrandt 

Quazi Shahidur Rahman Ronald R. Charpentier 

Muhammad Imaduddin Timothy R. Klett 

Humayun Ashraf Christopher J. Schenk 

Khondaker Shahjahan James W. Schmoker 

Mizanur Rahman Gregory F. Ulmishek 

Yousuf Ali Talukder 

 Assessor 

 Robert C. Milici 

Other Contributors 

Central Region Energy Team Regional Coordinator 

Gene Whitney, Chief Scientist Craig J. Wandrey 

Assessment Meeting Recorder/Graphics Geologist 

Susan M. Walden Peter D. Warwick 

GIS Specialist Graphics Specialist 

Feliks Persits Margarita Zyrianova 
Part I—Overview

Introduction

A natural gas assessment of the country of Bangladesh 

was conducted after a 21-month study performed by the U.S. 

Geological Survey (USGS) and funded by the U.S. Agency 

for International Development. This project culminated in an 

assessment meeting that was held in Denver, Colo., from January 16 to January 26, 2001. The assessment team consisted 

of six geologists from the USGS’s World Energy Resource 

Assessment Team and seven geologists, geophysicists, geochemists, and a petroleum engineer from Petrobangla. A 

regional assessment geologist from the USGS assigned to Bangladesh presented the geological and geophysical data needed 

for the formal assessment. International oil companies were 

invited to present geological background and assessment information and included Unocal Corporation, Shell Bangladesh, 

and Cairn Energy PLC. The goal was to assess the technically 

recoverable undiscovered gas resources of Bangladesh that 

might be found in a 30-year period (2000–2030).

The methodology used was that of the U.S. Geological 

Survey World Energy Assessment Team (2000) and is 

described in detail in that publication. This methodology has 

been used in assessments throughout the world. It has been 

reviewed extensively and formally endorsed by the American 

Association of Petroleum Geologists.

The USGS periodically conducts geologically based 

assessments of hydrocarbon resources of the United States and 

of the world. As part of the process, regional geologists present 

descriptions of the petroleum geology and known hydrocarbon 

resources of the region to be assessed to the assessment team. 

This information is used to identify and describe total petroleum systems (TPS) within the assessed region. As far as possible, total petroleum systems encompass the natural process 

that begins with the generation of hydrocarbons from kerogenrich source rocks, is followed by the migration of hydrocarbons from their source area, and ends with their entrapment 

within reservoir rocks beneath relatively impervious seals. The 

area (or country) in which that total petroleum system is active 

is then divided into assessment units (AU). Assessment units 

are areas of specifi c geological terrain and hydrocarbon development within a given total petroleum system. Available historical oil and gas production data from existing wells and 

fi elds and information on discovered prospects and leads are 

then allocated to each AU. The AU is characterized as to 

type of hydrocarbon—in this case gas rather than oil—the 

minimum fi eld size to be assessed (42 billion cubic feet of 

gas (BCFG) for Bangladesh), the number of discovered fi elds 

exceeding the minimum size, and the median size of discovered gas fi elds. Geologic elements may be risked only when 

no fi elds of the minimum fi eld size have been discovered 

within an AU. In such a hypothetical AU, assessment unit geologic risk probabilities are determined for adequate petroleum 

charge, reservoirs, traps, and seals—the timing of geologic 

events must be such that traps form in time to intercept migrating gases. These probabilities are multiplied together to determine the geological risk for an accumulation of one deposit 

equal to or greater than the minimum fi eld size. If there is no 

risk that one fi eld of minimum size will be discovered, the risk 

is 1. Accessibility is also risked to account for the possibility 

of adequate locations to allow for exploration for a fi eld equal 

to or greater than the minimum fi eld size to be found within 

a 30-year time frame.

Utilizing these data, their understanding of the geology 

and hydrocarbon potential of each AU, and their combined 

knowledge of world petroleum resources and geology of 

hydrocarbon accumulations worldwide, the assessment team 

conducts an iterative analysis of each AU until they reach 

a consensus on the ranges of the numbers and sizes of undiscovered fi elds (minimum, median, maximum) in that unit. 

These data are input onto a seventh approximation data form 

(Schmoker and Klett, 1999) and then into a computer program 

(EMC2, Charpentier and others, 2000) that generates probabilistic forecasts of the undiscovered resources contained within 

the AU, such as the amount of gas in gas fi elds, or oil in oil 

fi elds, and their coproducts.

Ratios of liquids to gas—and ancillary data such as the 

composition of the gas or oil, drilling depths, and depths of 

water (if offshore)—are entered onto the form, and allocations 

U.S. Geological Survey–PetroBangla 

Cooperative Assessment of Undiscovered 

Natural Gas Resources of Bangladesh

By USGS-Bangladesh Gas Assessment Team

1
are made as to the location of the resource; in this case, 

onshore vs. offshore. In this study, these data are used to 

calculate undiscovered resources of natural gas liquids and to 

allocate those resources to the onshore and offshore portions 

of Bangladesh. Data used in this study refl ect known fi eld size 

data provided by Petrobangla, and these fi elds were not grown 

in this analysis. Only undiscovered technically recoverable 

resources were estimated in this study.

In order to organize, catalog, spatially display, and query 

the large variety and quantities of data collected for this assessment a geographic information system (GIS) was developed. 

The GIS contained cultural, stratigraphic, structural, magnetic, 

gravity, reservoir, well, fi eld, production, and seismic data. The 

ability to interactively query, spatially display, and compare 

relevant information during the assessment greatly enhanced 

the assessment process. The GIS now provides a documented 

digital database on which the Government of Bangladesh and 

Petrobangla can build for future assessments.

Acknowledgments

Additional data was provided by independent oil companies (IOC’s) operating in Bangladesh. These IOC’s were 

Unocal Corporation, Shell Bangladesh, Carin PLC, and Haliburton.

Assessment of Gas Resources of Bangladesh

General Geology

Previously, the USGS had conducted an assessment of 

the Ganges-Brahmaputra Province, including parts of India 

and Myanmar and almost all of Bangladesh, as documented 

in the World Petroleum Assessment 2000. (U.S. Geological 

Survey World Energy Assessment Team, 2000). The current 

assessment refl ects new information for the time period 1995 

to 2000 and utilizes considerable proprietary data for this new 

Petrobangla/USGS country-level assessment.

The petroleum geology of Bangladesh may be traced back 

in time to the latest Paleozoic (350 million years ago) when 

the ancient continent of Pangea broke apart and fragments 

of the Earth’s crust began to migrate northward toward an ultimate collision with the southern portion of Asia. One of these 

lithospheric fragments, the Indian subcontinent, continued to 

drift throughout almost all of the Mesozoic and into the early 

Cenozoic before collision with southern Asia closed the ancient 

ocean on the north of the Indian subcontinent and drove up the 

Himalaya Mountain chain. At the same time, collision, subduction, and compressional forces formed the mountainous regions 

in Myanmar to the east and produced the geoanticlinorium of 

the Arakan Yoma in adjacent Myanmar and eastern India. These 

recently uplifted highlands to the north and east, as well as 

the ancient land mass of India on the west, were subsequently 

eroded and shed sediment into the deep basin to the east, south, 

and west into the area currently underlying the great GangesBrahmaputra delta. The sediments of the Ganges-Brahmaputra 

delta underlie almost all of Bangladesh, parts of eastern India, 

and West Bengal, India. Total sedimentary thickness in Bangladesh is unknown but probably exceeds 20,000 m in the area 

of the Surma Basin and in the southern part of the GangesBrahmaputra delta (fi g. 1). This thick pile of sediments overlies 

the deeply buried crust of the ancient Indian subcontinent on 

the west and now deeply buried oceanic crust on the east. On 

the east, where the oceanic crust beneath the delta is being 

subducted into the Earth beneath the Burma plate, the overlying 

sediments are being scraped off into a series of elongate, gentle 

to complexly faulted folds. 

The Tertiary Composite Total Petroleum System

Although the petroleum geology and hydrocarbon potential of the delta is not well understood and exploration for 

hydrocarbons is in its early stage in this region, the elements 

of one or more potential total petroleum systems have been 

identifi ed within the deltaic sediments. Possible source rocks, 

strata with greater than 0.5 percent total organic carbon, 

have been identifi ed in western Bangladesh and West Bengal, 

India, in the area occupied by the Surma Basin, and in the 

greater part of the subaerial delta and offshore regions in 

southern Bangladesh (Shamsuddin and Abdullah, 1977; Hajra 

and others, 1977, Bangladesh Oil Gas and Mineral Corporation, 1986). Sandstone reservoir rocks with high porosity (as 

much as 30 percent) are overlain by, and in places surrounded 

by, relatively impervious shale beds that seal gaseous and 

liquid hydrocarbons within traps and prevent them from escaping to the surface. Buried deeply in the subsurface, source 

rocks have been generating hydrocarbons almost since the 

formation of the delta. 

The eastern fold belt, known as the Chittagong-Tripura 

fold belt, contains large anticlinal folds that serve as traps for 

hydrocarbons within the Surma Basin and throughout much 

of eastern Bangladesh. These geologic structures have been 

forming for the last 5 million years, more or less, and thus far 

have proved to contain the largest gas fi elds in Bangladesh. 

Other traps abound and include a wide variety of stratigraphic 

traps and combinations of structural and stratigraphic traps. 

Extensional faulting and roll-over anticlines are a dominant 

structural trap in many of the world’s deltas and, given the 

high sedimentation rates of the Ganges-Brahmaputra delta, 

are certain to be an important type of trap in Bangladesh. 

Migration pathways from source rocks to reservoirs apparently 

occur along deep-seated steeply dipping to vertical faults, and 

laterally along porous zones within subhorizontal to gently 

dipping strata. 

In summary, although total petroleum systems are clearly 

working in the Ganges-Brahmaputra delta to produce hydrocarbons and transport them from their source rocks into sealed 

reservoirs, there is not yet enough data to correlate hydrocar2 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
bons in reservoirs with their specifi c source rocks, although a 

deep Oligocene formation appears to be the most likely source 

rock. The total petroleum system within this great Tertiary 

delta is treated as a single composite total petroleum system 

(TPS), the Bang01 Tertiary Composite total petroleum system. 

The nomenclature, coding system and supporting analytical 

database follows procedures formally described in the USGS 

World Petroleum 2000 (U.S. Geological Survey World Energy 

Assessment Team, 2000).

Assessment Units

The USGS-Bangladesh Gas Assessment Team divided the 

country into six assessment units, based to a large degree their 

geological structural attributes. These are: Bang0101 Surma 

Basin assessment unit; Bang0102 Easternmost Extremely 

Folded assessment unit; Bang0103 High-Amplitude Faulted 

Anticlines assessment unit; Bang0104 Moderately Folded Anticlines assessment unit; Bang0105 Western Slope assessment 

unit; and Bang0106 Western Platform assessment unit (fi g. 2). 

The fi rst pages of Addendum 1 show assessment summary 

results for the onshore region, offshore region, and the grand 

total for all of Bangladesh. The assessment results summary by 

assessment unit shows, in more detail, resources allocated to 

onshore and offshore areas as appropriate. In this assessment, 

offshore areas out to a depth of water of approximately 200 m 

were assessed. Graphical summaries of assessment results for 

each AU are shown in Addendum 1, and input data utilized in 

the probabilistic assessment process are shown in Addendum 2.

Figure 1. Generalized geologic map of Bangladesh and adjacent areas. Surma Basin is same as Sylhet 

Trough. Adapted from Shamsuddin and Abdullah (1997).

HIMALAYAN FOREDEEP

-16000

-14000

- 8000

- 6000

H I N

G

E

Z O N E

I N D I A N

S H I E L D

RAJ

TRP

-2000

-4000

UPPER ASSAM

WEST BENGAL

100 KM

880 900 920

0

22

0

24

- 14000

INDIA

INDIA

T

T

Teomp

MZ

MZ

MZ

Tpal

Teomp

pC

pC

pC

H I M A L A Y A M O U N T A I N S 

NAGA

C E N T R

A L B U R

M

A B A S I N

S

H

E

L

F

SYLHET TR.

Y

O

M

A

BURMA

SEDIMENT THICKNESS

ANTICLINE

GAS FIELD

GAS TEST

T

EDGE OF DELTA

SUTURE

THRUST FAULT

T

- 10000

- 12000

- 14000

- 16000

- 18000

- 20000

PATUAKHALL

DEPRESSION

TANGALL-TRIPURI

HIGH

F O L D B E L T

A

R

A

K

A N

B

sh

sa

kt

bg f

sm

BANGLADESH

U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 3
8.1 TCF

(1.8 - 18.1)

0.5 TCF

(0.2 - 0.9)

19 TCF

(6.1 - 36.2)

2.9 TCF

(0.5 - 6.5)

0.4 TCF

(0.1 - 0.7)

1.8 TCF

(0.5 - 3.5)

Bangladesh Country Assessment (

32.1 TCF

(8.4 - 65.7)

23.3 TCF

(6.0 - 48.3)

8.8 TCF

(2.4 - 17.4)

Onshore Offshore (< 200m wa

_

Petrobangla/USGS Natural Gas Assessm

of Undiscovered, Conventional Resourc

of Bangladesh

landwater

Total Petroleum System (Bangladesh)

BANG01 Tertiary Composite

Assessment Units (Bangladesh)

BANG0101 Surma BasinBANG0102 Easternmost Extremely Folded BBANG0103 High Amplitude Faulted AnticlineBANG0104 Moderately Folded AnticlinesBANG0105 Western SlopeBANG0106 Western Platform

Pod of Active Source Rocks (BangladeMinimum Petroleum System (Bangladefaults (from imagery?)hinge zone

Wells (Petrobangla, Excel file)

drygas & cond prodgas & cond shut ingas producinggas showgas shut in

gas, cond, oil, pdgas, cond, oil, abdoil & gas showsoil & gas shut inoil showsunidentified

Bathymetric Contours Contry bounda

Outer boundaryLease blocksLakesGraticule 1 deg

 -50 - -1500

Water-Land boundary

Figure 2. Estimates of undiscovered natural gas resources of Bangladesh. Mean estimate shown with F95–F5 range shown in parentheses.
Table 1. Stratigraphic nomenclature of Ganges-Brahmaputra delta in eastern India and Bangladesh.

SERIES Mishra and Singh Ganguly (1997)

(1997) Age Shelf and slope facies Basin facies Su

SYSTEM 

Pliocene and 

Pleistocene Dupitila Gr

Pliocene Debagram Fm. Ranaghat Fm. Tipam Group 

Late Oligocene to 

early Pliocene 

Ranaghat Fm. 

Matla Fm. 

Debagram Fm. 

Pandua Fm. 

Diamond Harbour 

Fm. 

Miocene Surma 

Group 

Pandua Fm. 

Diamond Harbour Fm

Oligocene Burdwan Fm. Oligocene Burdwan 

Fm. 

Barail 

Group 

Hoogly Fm. Kopili Fm. 

Kalighat Ls. Sylhet Ls Eocene Eocene Jaintia 

Group 

Jalangi Fm. 

TERTIARY 

Paleocene 

Ghatal Fm. 

Paleocene 

Jalangi Fm. 

(Chera Fm.)

Maastrichtian Bolpur Fm. 

Dhananjaypur Fm. 

CRETACEOUS 

Campanian 

Cretaceous 

Ghatal 

Fm. 

Bolpur Fm. 

Rajmahal trap

Permo-Carb. Permo- Carb. Gondwana

Archaean Precambrian Basement 

Matla Fm. 
Part II—Assessment Unit Descriptions

Bang0101: Surma Basin Assessment Unit

The Surma Basin assessment unit is a geophysically and 

geologically defi ned area in northeastern Bangladesh that contains a great thickness of Tertiary sedimentary strata. This 

AU is classifi ed as a frontier area, with nine discovered gas 

fi elds that exceed the minimum assessed size of 42 BCFG. 

The Surma Basin occurs to the south of the Precambrian Shillong Plateau, a crystalline massif that has been thrust up to 

the south along a footwall of Tertiary sedimentary strata. The 

basin contains as much as 20,000 m of sedimentary fi ll and 

is characterized by a conspicuous 50-milligal negative gravity 

anomaly. In general, the natural gases produced from this AU 

contain a greater amount of liquid hydrocarbons than do the 

gases produced elsewhere in Bangladesh.

The strata that comprise the explored part of the assessment unit in the Surma Basin range in thickness from about 

3,000 to 5,000 m (table 1). In general, their lithologies consist 

of deltaic, estuarine, and shallow-marine sandstones, siltstones, and shales that contain abundant plant-derived organic 

matter. Potentia- source rocks include shales and carbonaceous shales of Eocene, Oligocene, and Miocene age. These 

strata generally contain about 0.5 to 3 percent total organic 

carbon (TOC), although in places the content of organic 

matter may range up to 10.5 percent. Thermal maturation 

is suffi cient to generate natural gas and natural gas liquids 

throughout much of the area. Gas and condensates were generated at maturities equivalent to 1.1 to 1.3 percent vitrinite 

refl ectance (Ro) and at depths that range from about 6 to 

7.5 km (Unocal Corporation, unpub. data). Little oil has been 

discovered in a few of the Surma Basin wells. Migration is 

generally vertical along fractures and through porous strata. 

Hydrocarbon generation commenced a few tens of millions of 

years ago and has continued during the formation of the major 

anticlinal traps, which began forming only several million 

years ago.

Reservoir rocks in the Surma Basin are chiefl y Tertiaryage sandstones of the Boka Bil and Bhuban Formations (Miocene) that were deposited in fl uvial, deltaic, and estuarine 

environments. Porosity generally ranges from 10 to 20 percent. 

Reservoir sands range from thick channel-fi ll and littoral or 

marine-bar deposits to sandstones thinly interlaminated with 

shale and siltstone that were deposited in tidally infl uenced 

environments.

At the top of the Surma Group (table 1), a widespread 

unit, generally known as the upper marine shale (ums), serves 

as a regional hydrocarbon seal in the Surma Basin and elsewhere in Bangladesh. The major shale source beds may also 

serve as regional seals. In addition to the regionally distributed 

shale beds, there are several more locally distributed shale 

beds and shale-fi lled channels in the middle and lower parts 

of the Surma Group that support stacked reservoirs in several 

of the known fi elds. 

Structural and combination traps of Miocene age occur 

along stratigraphic boundaries, in sandstone-fi lled channel 

deposits, and in sandstone beds sealed laterally by shale-fi lled 

channels—these comprise major traps in the eastern part of the 

basin. In general, these sedimentary strata have been folded 

into several large-scale anticlines that are unfaulted or slightly 

to moderately faulted in the western and central parts of the 

basin. Folding and faulting is more intense toward the east 

within the Chittagong-Tripura fold belt and becomes progressively less intense to the west, where the folds are more broad 

and gentle. 

Major fi eld discoveries in this AU include Jalalabad, 

Beanibazar, Chhatak, Sylhet, Moulavibazar, Rashidpur, Fenchuganj, Bibiyana, Kailashtila, and Habiganj. Graphical summaries of known fi elds are shown in Addendum 2.

Bang0102: Eastern Extremely Folded 

Assessment Unit

This assessment unit is classifi ed as hypothetical because 

hydrocarbons in amounts exceeding the minimum fi eld size 

have not been found within it. This AU comprises the easternmost and most tectonically deformed AU in Bangladesh. It 

consists of at least 10 major anticlinal structures that bring 

strata as old as Miocene to the surface on their crests. The 

Tertiary-age stratigraphic units mapped in the tightly folded 

anticlinal structures in this area (Alam and others, 1990) are 

the same as those recognized in the subsurface of the Surma 

Basin. As a result of the intense folding and faulting, the 

source rocks and reservoir rocks of the Surma Basin are 

exposed at the surface in this area where the anticlines are 

breached by erosion. The few wells that have been drilled in 

this area tested the upper part of the Surma Group, and all 

were plugged and abandoned. The Patiya well near Rangamati, 

drilled into the Miocene in 1953 by Pakistan Petroleum, Ltd., 

encountered a show of oil in Miocene strata. 

The strata exposed in the anticlinal structures that comprise this assessment unit are about 3,000 m thick (Baqi and 

others, 1995) In general, their lithologies consist of basinal 

turbidites and deep- to shallow-marine deposits in the lower 

part, to shallow-marine and fl uvial deposits in the upper 

part of the exposed stratigraphic section. Bouma sequences 

have been identifi ed in the lower and middle parts of the 

exposed stratigraphic section, suggesting deep-water sedimentation, whereas the upper part contains abundant burrows and 

shallow-water marine fossils that suggest shallow-water sedimentation. Potential source rocks in the exposed part of the 

section include the marine shales and carbonaceous shales of 

the Bhuban and Boka Bil Formations (Miocene) and buried 

source rocks of Oligocene age. The Miocene-age shale-dominated units may be as much as 500 m thick (Baqi and others, 

1995). The presence of hydrocarbons in the region indicates 

that thermal maturation is suffi cient to generate natural gas and 

natural gas liquids throughout much of the area. 

6 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
Migration is generally vertical along fractures and lateral 

through porous strata. Hydrocarbon generation commenced a 

few tens of millions of years ago and has continued during 

the formation of the major anticlinal traps, which began only 

about 5 million years ago. Reservoir rocks in the this AU are 

chiefl y Tertiary-age sandstones that were deposited in deepto shallow-marine environments, and the seals are the interbedded shale-dominated units that, in places, are as much as 500 

m thick. Folded marine sandstone beds, sandstone-fi lled channel deposits, and sandstone beds sealed laterally by shale-fi lled 

channels of Miocene age constitute potential traps in the Boka 

Bil and Bhuban Formations. Because the major structures have 

been breached by erosion, likely exploration targets would be 

along the noses of major plunging anticlines where the structures descend into the subsurface and on the smaller anticlinal 

closures that occur in the synclinal regions between major 

breached anticlinal structures.

Bang0103: High-Amplitude Faulted Anticlines 

Assessment Unit

This assessment unit is classifi ed as frontier because it has 

only one fi eld that exceeds the minimum size of 42 BCFG. The 

High-Amplitude Faulted Anticlines assessment unit occupies 

the area east of the Moderately Faulted Anticlines assessment 

unit and west of the Easternmost Extremely Faulted assessment unit in easternmost Bangladesh. It consists of at least 

seven major anticlinal structures that bring strata as old as 

Miocene up to the surface in their cores. The Tertiary-age 

stratigraphic units mapped in the tightly folded anticlinal structures in this area (Alam and others, 1990) are the same as those 

recognized in the subsurface of the Surma Basin. As a result 

of the intense folding and faulting, however, the source rocks 

and reservoir rocks correlative to those in the Surma Basin 

are exposed at the surface in this area where the anticlines 

are breached by erosion. The Semutang fi eld is the only fi eld 

discovered in this area—by the Pakistan Oil and Gas Development Corporation—and it is not producing. Semutang is 

located on the plunging nose of an anticline that is breached 

at least to the level of the Boka Bil Formation to the north, at 

the Indian border. Prospects at Sitakund and Jaldi have yielded 

shows of hydrocarbons, and the Haldi prospect was dry. 

This assessment unit was separated from Bang0102 

because it is not as greatly deformed structurally and contains 

a discovered gas fi eld. In general, the petroleum geology of the 

two regions is much the same.

Bang0104: Moderately Folded Anticlines 

Assessment Unit

This assessment unit is classifi ed as a frontier unit 

because it has only nine fi elds that exceed the minimum size 

of 42 BCFG. The Bengal foredeep, the large area generally 

to the south of the Surma Basin, is in the more distal region 

of the thick Tertiary deltaic deposits of the Ganges-Brahmaputra delta. Overall, the sediments of the AU are as thick as 

20,000 m in the Patuakhali depression, a depocenter located 

in the southeastern side of the delta (Shamsuddin and Abdullah, 1997; Ganguly, 1997). Like Bang0102 and Bang0103, the 

Tertiary and Quaternary strata in this AU are deformed into 

a series of plunging folds because of subduction beneath the 

Arakan Yoma geoanticlinorium to the east. In this AU, anticlinal structures range from tightly folded, elongate, and faulted 

structures on the east to broad, open, relatively unfaulted structures on the west. 

The Bengal foredeep contains the great volume of Tertiary sediments of the delta. In general, the basin-fi ll consists 

of sandstones, siltstones, and shales that commonly contain 

plant-derived organic matter. The strata that comprise this AU 

are more distal equivalents of the Oligocene Barail Group, 

the Miocene Surma Group, and the Pliocene Tipam Group in 

the Surma Basin and in the folded belts to the east. Current 

drilling depths generally range from about 3.5 to 4.5 km in the 

southeastern part of the delta. 

Cairn Energy and Shell Bangladesh have devised an 

informal megasequence classifi cation for the strata in the 

southern and offshore regions of Bangladesh. The megasequences are identifi ed on seismic cross sections, and they are 

based upon the overall character of their bed forms. In general, 

megasequence 1 (MS 1) at the base of seismically imaged 

sections consists of major progradational bed forms that are 

overlain by generally subhorizontal aggradational bed forms. 

These bed forms are overlain by the highly channelized and 

canyonized bed forms of megasequence 2 (MS 2). Regionally, 

the channel-like bed forms in MS 2 may represent (1) deeply 

eroded submarine canyons in the more distal, southern part of 

the delta and (2) fi lled subaerial valleys of much less local 

relief in the northern part of the AU and in the adjacent 

Surma Basin. The upper part of the section, represented by 

megasequence 3 (MS 3), consists also of progradational and 

aggradational bed forms generally similar to those of MS 1. 

In the nearshore and offshore areas of southeastern Bangladesh, about 1 to 1.5 km of MS 1 are imaged at the base 

of the seismic sections, MS 2 is about 2.5 km thick, and MS 

3 at the top of the seismic sections may be as thick as 1 km. 

The Miocene-Pliocene boundary has been identifi ed as near 

the middle of MS 2 using biostratigraphic markers. If this is 

correct, then the Tipam and Dupitila Groups in BANG0104 to 

the east would be approximately equivalent to MS 2.

Although the source rocks in this area have not been 

identifi ed with certainty, they probably contain woody organic 

matter in shale, shaly coal beds, and coal from deeper Miocene 

and Oligocene source rocks. The stratigraphic positions of 

the source beds are uncertain, and the hydrocarbons may be 

generated from relatively low concentrations of organic matter 

distributed throughout a large volume of sediments. In addition, there is some evidence of potential marine source rocks 

and more deeply buried Oligocene source rocks beneath the 

U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 7
levels currently imaged on seismic refl ection data. Potential 

source rocks from Oligocene to mid-Miocene age are within 

or have passed through the main gas-generating window prior 

to and during the development of the major anticlines. The 

low concentration of liquid hydrocarbons in fi elds from the 

southern limit of the Surma Basin to offshore southeastern 

Bangladesh demonstrates that source rocks, wherever they are, 

are at an appropriate level of thermal maturation to have generated large amounts of natural gas. Migration pathways are 

complex and are generally vertical along faults and fractures 

and via gas chimneys, and lateral through porous sandstones. 

Overpressured zones at depth may be a control on migration 

and may impact seal integrity. Such zones are believed to 

have signifi cant future potential for gas resources in Bangladesh. Future discoveries are expected within this overpressured zone, roll-over anticlines in extensional down-to-thebasin structures, and in a great variety of stratigraphic and 

combination traps, many near known structures.

Reservoir rocks are in deltaic, littoral, and marine sandstones in the upper part of MS 1 and in the sandstone channelfi ll deposits of MS 2. Porosity ranges generally from 10 to 25 

percent. Evidence from onshore sections to the east indicate 

that some of these Tertiary strata may have been deposited as 

turbidites in relatively deep water.

Major discoveries in this assessment unit include the following fi elds: Titas, Bakhrabad, Megna, Narsingdi, Shaldanadi, Kamta, Feni, Shahbazpur, Kutubdia, and Sangu. Data on 

those fi elds are shown in Addendum 2.

Bang0105: Western Slope Assessment Unit

The Western Slope assessment unit occupies the region 

between the Moderately Faulted Anticlines assessment unit on 

the east and the Western Platform assessment unit on the west. 

It is classifi ed as hypothetical because no gas fi elds larger than 

42 BCFG have been found in this sparsely explored area . 

Tectonically, the region is generally unfolded, and the major 

structures appear to be extensional rather than compressional. 

The Tertiary strata of the assessment unit apparently overlie 

extended and thinned (transitional) continental crust in the 

northern part of the AU, and oceanic crust in nearshore and 

offshore regions to the south. All told, the sedimentary strata 

in this AU range from about 7 km thick along the edge of 

the slope to perhaps several tens of kilometers thick in the 

offshore region of Bangladesh. The possibility of deep-marine 

sediments—submarine fans—at the base of prograding clonoforms seaward of a paleo hinge line were also considered in 

this AU.

Sedimentary input into this part of the Bengal Basin consists of components from two major source areas, the Precambrian Indian craton on the west and the tectonic highlands of 

the Himalayan Mountains and, perhaps, the Arakan Yoma on 

the north and east, respectively. Basement east of the Tertiary 

shelf edge in Bangladesh most likely consists of Precambrian 

igneous and metamorphic rocks that have been intermittently 

deformed, extended, and thinned by extensional forces from 

the Permian through the Cretaceous. Overlying fi ne-grained 

siliciclastic strata of early Tertiary age, perhaps interbedded 

with a few thin limestones, appear to have been deposited 

as eastward-prograding wedges along the margin of the northward-drifting subcontinent. As the Indian subcontinent closed 

with the southern part of the Asian continent, anoxia may have 

developed in the ever-restricted deep basin of the Tethys sea 

prior to collision so that oil-prone source rocks developed in 

the deep basin to the east of the Tertiary shelf edge. After 

collision of the Indian subcontinent with Asia and the development of tectonic highlands to the north and east, these older, 

westward-derived strata were covered by the younger Tertiary 

and Quaternary clastic deposits of the developing GangesBrahmaputra River system. These younger strata are most 

likely direct correlatives with the megasequences described in 

the AU to the east. Accordingly, potential source rocks, seals, 

and reservoirs are expected to be similar to those in Bang0104. 

Some geologic risk of not fi nding an accumulation greater than 

42 BCFG was accommodated because only one unsuccessful 

exploratory test has been drilled, and the area is essentially 

untested.

This AU has not been compressionally deformed by the 

processes of crustal subduction that has deformed easternmost 

Bangladesh. Major compressional structures are absent, and 

expected structural traps will be related to extensional deformation, where listric down-to-the-basin faults have resulted in 

the formation of roll-over anticlines. These extensional faults 

may provide vertical migration pathways for hydrocarbons that 

matured in more deeply buried source rocks. Stratigraphic 

traps are anticipated to be abundant, and charging with hydrocarbons is expected to have occurred early in the depositional 

history of this part of the basin as potential source rocks and 

porous reservoirs were buried ever more deeply within the 

sedimentary basin. 

Thus far, this large region of the delta has been little 

explored, and no discoveries have been made therein.

Bang0106: Western Platform Assessment Unit

This assessment unit is classifi ed as hypothetical since no 

fi elds have been found that exceed the minimum fi eld size of 

42 BCFG. In northwestern Bangladesh, the Western Platform 

assessment unit consists of several buried regional geologic 

structures. These structures are the eastward-inclined Bogra 

shelf of early Tertiary age that is terminated on the east by 

a paleo hinge line, a buried structural saddle adjacent to the 

Shillong Plateau, and a small area in northwesternmost Bangladesh that dips northwest into the Himalayan foredeep. This 

area was assessed collectively as the Western Platform assessment unit. Collectively, the Mesozoic and Cenozoic strata in 

this area are about 5 to 7 km thick and consist both of precollisional sequences that were deposited prior to and during 

the northward drift of the Indian subcontinent and the postcollisional sequences that were deposited in mid- to late-Ter8 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
tiary time. As in the previous assessment unit, early Tertiary 

strata consist of several hundred meters of siliciclastic and carbonate rock that in places serve as potential source rocks and 

reservoirs. Although overlying Tertiary strata are dominated 

by sandstones and siltstones of good reservoir quality, the 

capacity for seals within these rocks has not been demonstrated. These strata have been drilled in numerous places 

in West Bengal, India, and in a few places in western Bangladesh. Although prospects and leads have been identifi ed along 

unconformities, in porous limestones, and along extensional 

structures, only a few shows of hydrocarbons have been discovered thus far. The most prospective areas of this assessment 

unit may be along the shelf edge, where hydrocarbons generated in the adjacent deep basin have migrated upward into 

traps to the west. Analogous geologic settings in West Bengal, 

India, appear to have a modest hydrocarbon potential.

The Western Platform assessment unit is underlain at 

depth by a Permian coal petroleum system, which may contain 

coal-bed gas in continuous accumulations within extensional 

Gondwana basins. This petroleum system was not assessed in 

this study.

Perspective of the Assessment

The six assessment units defi ned in this study use known 

geological and engineering information as a basis for estimating the technically recoverable, conventional, undiscovered gas 

resources of Bangladesh. The resource numbers calculated 

indicate the range of probable resources that may be discovered if Bangladesh were actively explored during a 30-year 

time frame. In places, where detailed geologic information is 

lacking in Bangladesh, the assessment team used geological 

play types that occur in similar geological provinces elsewhere 

in the world as analogs for potential hydrocarbon occurrences 

in Bangladesh. In addition to the fairly well understood structural anticlines, which have thus far constituted the main play 

in Bangladesh, the assessment team recognized the potential 

offered by stratigraphic traps; plays at depth within the highpressure zone; and traps associated with turbidite formations, 

carbonate reefs and build-ups, buried hill plays, extensional 

down-to-the-basin faults and associated roll-over anticlines, 

etc. It is anticipated that, during the next 30 years, each of 

these play concepts will be explored and tested, at least to 

some extent, so that the hydrocarbon potential of Bangladesh 

will be more completely realized.

The assessment team also considered the possible technological advances that may occur within this 30-year time frame 

that would allow explorationists to visualize and understand 

subsurface accumulations of hydrocarbons better than they do 

today. In addition, improvement of production technologies 

may well add a considerable volume of already-discovered 

hydrocarbons to the recoverable resource base. These projected advances in technology are based upon our past experience in the evolution of technology as we continually increase 

our ability to understand the complexities of petroleum geology and to improve our capabilities for exploration and extraction. 

The assessment team assumed a minimum fi eld size of 42 

BCFG (7 million barrels of oil equivalent (MMBOE)) for this 

assessment. This minimum fi eld size is anticipated to become 

economic some time in the future if suffi cient infrastructure 

is constructed. 

This country-based study is the fi rst step in a continuous 

assessment process that is expected to be replicated and 

updated with additional information generated since the previous assessment. With each subsequent assessment, greater 

levels of refi nement will result in a better level of confi dence 

and more accurate probability distributions for the remaining 

undiscovered gas resources of Bangladesh. 

References Cited

Alam, K., Hasan, A.K.M.S., Kahn, M.R., and Whitney, J.W., 1990, 

Geological map of Bangladesh: Geological Survey of Bangladesh 

Geological Map, scale 1:1,000,000.

Bangladesh Oil Gas and Mineral Corporation, 1986, Habitat of 

hydrocarbons in Bangladesh: Report on the Hydrocarbon Habitat 

Study (1984–1986) of the Peoples Republic of Bangladesh, v. 1 

[text], 192 p. and v. 2 [fi gures and tables].

Baqi, M.A., Islam, A., and Hossain, A., 1995, Sedimentary structures 

of the Waylataung anticline, Bangladesh: Bangladesh Journal of 

Geology, v. 14, p. 43–52.

Charpentier, R.R., and Klett, T.R., Monte Carlo simulation method, 

in World Energy Assessment Team, 2000, U.S. Geological Survey 

World Petroleum Assessment 2000—Description and Results, 

chap. MC: USGS Digital Data Series DDS-60 [multi-disc set], 

version 1.0.

Hajra, P.N., Barua, T.K., Guha, S., Rudra, M., Purkait, P.N., and 

Battacharya, M., 1997, A geochemical assessment of Bengal Basin: 

Indian Journal of Geology, v. 69, no. 2, p. 122–145.

Ganguly, S., 1997, Petroleum geology and exploration history of the 

Bengal Basin in India and Bangladesh: Indian Journal of Geology, 

v. 69, no. 1, p. 1–25.

Shamsuddin, A.K.M., and Abdullah, S.K.M., 1997, Geologic evolution of 

the Bengal Basin and its implication in hydrocarbon exploration in 

Bangladesh: Indian Journal of Geology, v. 69, no. 2, p. 93–121.

Schmoker, J.W., and Klett, T.R., 1999, U.S. Geological Survey 

assessment model for undiscovered conventional oil, gas, and NGL 

resources—The seventh approximation: U.S. Geological Survey 

Bulletin 2165, version 1.0.

World Energy Assessment Team, 2000, U.S. Geological Survey World 

Petroleum Assessment 2000—Description and Results: USGS 

Digital Data Series DDS-60 [multi-disc set], version 1.0.

U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 9
Code and Field MFS Prob. Type (BCFG) (0-1) F95 F50 F5 Mean F95 F50 F5 

Total: Onshore portions of Bangladesh Gas Fields 42 1.00 5,989 21,116 48,336 23,339 25 97 265 Total: Offshore portions of Bangladesh (to 200 m water depth)

Gas Fields 42 1.00 2,442 8,055 17,367 8,777 4 16 42 

Grand Total: Bangladesh

Gas Fields 42 1.00 8,431 29,171 65,703 32,116 29 113 307 

Gas (BCFG) NGL (MMBNGL)

Petrobangla/USGS Joint Assessment of Gas in Bangladesh

Assessment Results Summary

[BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. MFS, minimum field size assessed (BCFG). Prob., probability (includin

geologic and accessibility probabilities) of at least one field equal to or greater than the MFS. Results shown are fully risked estimates. For gas fields, all l

included under the NGL (natural gas liquids) category. F95 represents a 95 percent chance of at least the amount tabulated. Other fractiles are defined s

Fractiles are additive under the assumption of perfect positive correlation]

Undiscovered Resources
Code and Field MFS Prob. Type (BCFG) (0-1) F95 F50 F5 Mean F95 F50 

Gas (BCFG) NGL (MMBNG

Petrobangla/USGS Joint Assessment of Gas in Bangladesh Assessment Results Summary [BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. MFS, minimum field size assessed (BCFG). Prob., proba

geologic and accessibility probabilities) of at least one field equal to or greater than the MFS. Results shown are fully risked estimates. For g

included under the NGL (natural gas liquids) category. F95 represents a 95 percent chance of at least the amount tabulated. Other fractiles 

Fractiles are additive under the assumption of perfect positive correlation] Undiscovered Resources BANG01 Tertiary Composite Total Petroleum System BANG0101 Gas Fields 42 1.00 1,805 7,120 18,068 8,140 17 69 

BANG0102 Gas Fields 42 0.70 0 366 868 358 0 <0.5 

BANG0103 Gas Fields 42 1.00 521 1,611 3,485 1,762 13

BANG0104 Gas Fields 42 1.00 3,663 10,571 21,728 11,406 7 21 BANG0104 Gas Fields 42 1.00 2,442 7,047 14,486 7,604 4 14 

BANG0105 Gas Fields 42 0.90 0 1,233 3,521 1,433 02BANG0105 Gas Fields 42 0.90 0 1,008 2,881 1,173 02BANG0106 Gas Fields 42 0.64 0 215 666 24002

Surma Basin Assessment Unit Easternmost Extremely Folded Belt Assessment Unit Western Shelf Assessment Unit (45% allocated to OFFSHORE portion) Western Platform Assessment Unit Moderately Folded Anticlines Assessment Unit (40% allocated to OFFSHORE portion) Western Shelf Assessment Unit (55% allocated to ONSHORE portion) High Amplitude Faulted Anticlines Assessment Unit Moderately Folded Anticlines Assessment Unit (60% allocated to ONSHORE portion)
12 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0101

Surma Basin

Monte Carlo Results

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 22,500.00 BCFG

Entire range is from 438.77 to 42,121.10 BCFG

After 50,000 trials, the standard error of the mean is 23.11

Statistics: Value

Trials 50000

Mean 8,139.65

Median 7,119.87

Mode ---

Standard Deviation 5,168.02

Variance 26,708,466.53

Skewness 1.02

Kurtosis 4.08

Coefficient of Variability 0.63

Range Minimum 438.77

Range Maximum 42,121.10

Range Width 41,682.34

Mean Standard Error 23.11

Frequency Chart

 BCFG

.000

.005

.011

.016

.021

0

267.7

535.5

803.2

1071

0.00 5,625.00 11,250.00 16,875.00 22,500.00

50,000 Trials 686 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 13

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 438.77

95% 1,805.33

90% 2,429.61

85% 2,977.54

80% 3,517.21

75% 4,057.01

70% 4,631.82

65% 5,223.53

60% 5,822.78

55% 6,460.90

50% 7,119.87

45% 7,813.64

40% 8,530.25

35% 9,313.89

30% 10,162.64

25% 11,120.65

20% 12,246.29

15% 13,604.86

10% 15,278.96

5% 18,067.89

0% 42,121.10

End of Forecast
14 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 225.00 MMBNGL

Entire range is from 3.72 to 432.87 MMBNGL

After 50,000 trials, the standard error of the mean is 0.25

Statistics: Value

Trials 50000

Mean 81.45

Median 69.14

Mode ---

Standard Deviation 55.16

Variance 3,042.88

Skewness 1.22

Kurtosis 4.78

Coefficient of Variability 0.68

Range Minimum 3.72

Range Maximum 432.87

Range Width 429.15

Mean Standard Error 0.25

Frequency Chart

 MMBNGL

.000

.006

.011

.017

.022

0

279.2

558.5

837.7

1117

0.00 56.25 112.50 168.75 225.00

50,000 Trials 1,091 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 15

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 3.72

95% 16.97

90% 23.07

85% 28.45

80% 33.69

75% 39.09

70% 44.44

65% 50.26

60% 56.18

55% 62.48

50% 69.14

45% 76.15

40% 83.41

35% 91.55

30% 100.38

25% 110.74

20% 122.77

15% 137.63

10% 157.04

5% 188.99

0% 432.87

End of Forecast
16 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 0.00 to 7,000.00 BCFG

Entire range is from 56.91 to 9,988.54 BCFG

After 50,000 trials, the standard error of the mean is 8.15

Statistics: Value

Trials 50000

Mean 2,157.25

Median 1,574.82

Mode ---

Standard Deviation 1,823.21

Variance 3,324,105.68

Skewness 1.72

Kurtosis 6.01

Coefficient of Variability 0.85

Range Minimum 56.91

Range Maximum 9,988.54

Range Width 9,931.63

Mean Standard Error 8.15

Frequency Chart

 BCFG

.000

.008

.015

.023

.031

0

386.5

773

1546

0.00 1,750.00 3,500.00 5,250.00 7,000.00

50,000 Trials 1,659 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 17

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 56.91

95% 395.64

90% 536.30

85% 659.93

80% 777.69

75% 891.78

70% 1,012.64

65% 1,140.35

60% 1,272.68

55% 1,417.82

50% 1,574.82

45% 1,749.86

40% 1,944.09

35% 2,169.99

30% 2,447.15

25% 2,778.96

20% 3,220.65

15% 3,778.87

10% 4,663.12

5% 6,181.70

0% 9,988.54

End of Forecast
18 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 7

Likeliest 12

Maximum 80

Selected range is from 7 to 80

Mean value in simulation was 33

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 222.71 264.71

Standard Deviation 908.95 908.95

Selected range is from 0.00 to 9,958.00 42.00 to 10,000.00

Mean value in simulation was 203.29 245.29

7 25 44 62 80

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 19

Assessment Unit BANG0101

Surma Basin

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 5.00

Likeliest 10.00

Maximum 15.00

Selected range is from 5.00 to 15.00

Mean value in simulation was 10.01

End of Assumptions

Simulation started on 1/25/01 at 19:16:10

Simulation stopped on 1/25/01 at 19:39:56

0.33 2,137.63 4,274.93 6,412.23 8,549.53

Sizes of Gas Fields

5.00 7.50 10.00 12.50 15.00

LGR in Gas Fields
20 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0102

Eastern Extremely Folded Belt

Monte Carlo Results

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 1,100.00 BCFG

Entire range is from 44.04 to 1,667.61 BCFG

After 50,000 trials, the standard error of the mean is 1.00

Statistics: Value

Trials 50000

Mean 511.82

Median 487.50

Mode ---

Standard Deviation 222.76

Variance 49,622.89

Skewness 0.48

Kurtosis 2.88

Coefficient of Variability 0.44

Range Minimum 44.04

Range Maximum 1,667.61

Range Width 1,623.57

Mean Standard Error 1.00

Frequency Chart

 BCFG

.000

.005

.010

.015

.020

0

253

506

759

1012

0.00 275.00 550.00 825.00 1,100.00

50,000 Trials 396 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 21

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 44.04

95% 182.70

90% 238.32

85% 279.55

80% 314.19

75% 344.61

70% 373.81

65% 402.33

60% 430.80

55% 458.35

50% 487.50

45% 517.78

40% 549.40

35% 582.43

30% 619.59

25% 659.93

20% 704.58

15% 757.31

10% 819.56

5% 911.57

0% 1,667.61

End of Forecast
22 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 1.50 MMBNGL

Entire range is from 0.03 to 2.36 MMBNGL

After 50,000 trials, the standard error of the mean is 0.00

Statistics: Value

Trials 50000

Mean 0.54

Median 0.48

Mode ---

Standard Deviation 0.30

Variance 0.09

Skewness 1.13

Kurtosis 4.62

Coefficient of Variability 0.56

Range Minimum 0.03

Range Maximum 2.36

Range Width 2.33

Mean Standard Error 0.00

Frequency Chart

 MMBNGL

.000

.006

.012

.018

.024

0

303.7

607.5

911.2

1215

0.00 0.38 0.75 1.13 1.50

50,000 Trials 461 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 23

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.03

95% 0.17

90% 0.21

85% 0.25

80% 0.29

75% 0.32

70% 0.35

65% 0.38

60% 0.41

55% 0.45

50% 0.48

45% 0.52

40% 0.55

35% 0.60

30% 0.64

25% 0.69

20% 0.76

15% 0.84

10% 0.95

5% 1.13

0% 2.36

End of Forecast
24 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 25.00 to 275.00 BCFG

Entire range is from 44.04 to 399.48 BCFG

After 50,000 trials, the standard error of the mean is 0.24

Statistics: Value

Trials 50000

Mean 119.58

Median 105.04

Mode ---

Standard Deviation 53.14

Variance 2,823.49

Skewness 1.78

Kurtosis 7.05

Coefficient of Variability 0.44

Range Minimum 44.04

Range Maximum 399.48

Range Width 355.44

Mean Standard Error 0.24

Frequency Chart

 BCFG

.000

.008

.015

.023

.031

0

385.7

771.5

1543

25.00 87.50 150.00 212.50 275.00

50,000 Trials 1,111 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 25

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 44.04

95% 63.85

90% 70.11

85% 75.06

80% 79.35

75% 83.50

70% 87.58

65% 91.67

60% 95.94

55% 100.33

50% 105.04

45% 110.32

40% 116.15

35% 122.59

30% 130.16

25% 139.33

20% 150.48

15% 165.69

10% 188.34

5% 227.24

0% 399.48

End of Forecast
26 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields

Summary:

Display range is from 0.00 to 1,200.00 BCFG

Entire range is from 0.00 to 1,667.61 BCFG

After 50,000 trials, the standard error of the mean is 1.34

Statistics: Value

Trials 50000

Mean 358.08

Median 365.69

Mode 0.00

Standard Deviation 300.03

Variance 90,020.09

Skewness 0.31

Kurtosis 2.16

Coefficient of Variability 0.84

Range Minimum 0.00

Range Maximum 1,667.61

Range Width 1,667.61

Mean Standard Error 1.34

Frequency Chart

 BCFG

.000

.075

.151

.226

.301

0

15050

0.00 300.00 600.00 900.00 1,200.00

50,000 Trials 94 Outliers

Forecast: G-Risked Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 27

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 0.00

95% 0.00

90% 0.00

85% 0.00

80% 0.00

75% 0.00

70% 0.00

65% 208.54

60% 272.85

55% 322.01

50% 365.69

45% 406.61

40% 446.58

35% 487.48

30% 531.42

25% 578.59

20% 630.81

15% 692.70

10% 764.70

5% 868.50

0% 1,667.61

End of Forecast
28 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields

Summary:

Display range is from 0.00 to 1.50 MMBNGL

Entire range is from 0.00 to 2.36 MMBNGL

After 50,000 trials, the standard error of the mean is 0.00

Statistics: Value

Trials 50000

Mean 0.38

Median 0.34

Mode 0.00

Standard Deviation 0.35

Variance 0.13

Skewness 0.89

Kurtosis 3.69

Coefficient of Variability 0.94

Range Minimum 0.00

Range Maximum 2.36

Range Width 2.36

Mean Standard Error 0.00

Frequency Chart

 MMBNGL

.000

.075

.151

.226

.301

0

15050

0.00 0.38 0.75 1.13 1.50

50,000 Trials 317 Outliers

Forecast: G-Risked NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 29

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.00

95% 0.00

90% 0.00

85% 0.00

80% 0.00

75% 0.00

70% 0.00

65% 0.19

60% 0.25

55% 0.30

50% 0.34

45% 0.39

40% 0.43

35% 0.48

30% 0.53

25% 0.59

20% 0.66

15% 0.74

10% 0.86

5% 1.05

0% 2.36

End of Forecast
30 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 1

Likeliest 6

Maximum 15

Selected range is from 1 to 15

Mean value in simulation was 7

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 28.75 70.75

Standard Deviation 35.80 35.80

Selected range is from 0.00 to 358.00 42.00 to 400.00

Mean value in simulation was 28.34 70.34

1 5 8 12 15

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 31

Assessment Unit BANG0102

Eastern Extremely Folded Belt

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 0.50

Likeliest 0.67

Maximum 2.00

Selected range is from 0.50 to 2.00

Mean value in simulation was 1.06

End of Assumptions

Simulation started on 1/25/01 at 19:48:49

Simulation stopped on 1/25/01 at 20:01:49

0.99 82.78 164.56 246.35 328.14

Sizes of Gas Fields

0.50 0.88 1.25 1.63 2.00

LGR in Gas Fields
32 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 4,500.00 BCFG

Entire range is from 91.11 to 6,910.01 BCFG

After 50,000 trials, the standard error of the mean is 4.17

Statistics: Value

Trials 50000

Mean 1,761.63

Median 1,611.47

Mode ---

Standard Deviation 931.80

Variance 868,249.45

Skewness 0.82

Kurtosis 3.62

Coefficient of Variability 0.53

Range Minimum 91.11

Range Maximum 6,910.01

Range Width 6,818.91

Mean Standard Error 4.17

Frequency Chart

 BCFG

.000

.005

.011

.016

.022

0

272.7

545.5

818.2

1091

0.00 1,125.00 2,250.00 3,375.00 4,500.00

50,000 Trials 429 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 33

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 91.11

95% 520.82

90% 685.68

85% 817.15

80% 935.95

75% 1,048.98

70% 1,157.63

65% 1,266.83

60% 1,376.76

55% 1,491.62

50% 1,611.47

45% 1,736.24

40% 1,869.45

35% 2,008.32

30% 2,156.42

25% 2,329.86

20% 2,527.63

15% 2,752.00

10% 3,044.63

5% 3,485.33

0% 6,910.01

End of Forecast
34 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 10.00 MMBNGL

Entire range is from 0.13 to 22.39 MMBNGL

After 50,000 trials, the standard error of the mean is 0.01

Statistics: Value

Trials 50000

Mean 3.72

Median 3.18

Mode ---

Standard Deviation 2.38

Variance 5.67

Skewness 1.39

Kurtosis 5.77

Coefficient of Variability 0.64

Range Minimum 0.13

Range Maximum 22.39

Range Width 22.26

Mean Standard Error 0.01

Frequency Chart

 MMBNGL

.000

.006

.011

.017

.022

0

278.5

557

835.5

1114

0.00 2.50 5.00 7.50 10.00

50,000 Trials 1,102 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 35

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.13

95% 0.93

90% 1.25

85% 1.52

80% 1.75

75% 1.99

70% 2.22

65% 2.45

60% 2.68

55% 2.92

50% 3.18

45% 3.45

40% 3.74

35% 4.07

30% 4.44

25% 4.88

20% 5.38

15% 6.04

10% 6.92

5% 8.37

0% 22.39

End of Forecast
36 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 0.00 to 1,400.00 BCFG

Entire range is from 46.35 to 1,999.84 BCFG

After 50,000 trials, the standard error of the mean is 1.40

Statistics: Value

Trials 50000

Mean 416.79

Median 319.78

Mode ---

Standard Deviation 312.71

Variance 97,785.84

Skewness 1.96

Kurtosis 7.55

Coefficient of Variability 0.75

Range Minimum 46.35

Range Maximum 1,999.84

Range Width 1,953.49

Mean Standard Error 1.40

Frequency Chart

 BCFG

.000

.009

.018

.027

.036

0

447.5

895

1790

0.00 350.00 700.00 1,050.00 1,400.00

50,000 Trials 1,034 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 37

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 46.35

95% 118.02

90% 144.31

85% 166.59

80% 187.33

75% 207.46

70% 227.44

65% 248.86

60% 271.13

55% 295.04

50% 319.78

45% 348.86

40% 382.42

35% 419.40

30% 463.96

25% 516.86

20% 585.61

15% 677.52

10% 813.76

5% 1,070.51

0% 1,999.84

End of Forecast
38 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 2

Likeliest 11

Maximum 35

Selected range is from 2 to 35

Mean value in simulation was 16

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 72.02 114.02

Standard Deviation 170.67 170.67

Selected range is from 0.00 to 1,958.00 42.00 to 2,000.00

Mean value in simulation was 68.23 110.23

2 10 19 27 35

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 39

Assessment Unit BANG0103

High-Amplitude Faulted Anticlines

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 1.00

Likeliest 1.33

Maximum 4.00

Selected range is from 1.00 to 4.00

Mean value in simulation was 2.11

End of Assumptions

Simulation started on 1/26/01 at 13:52:22

Simulation stopped on 1/26/01 at 14:08:35

0.45 432.88 865.30 1,297.73 1,730.15

Sizes of Gas Fields

1.00 1.75 2.50 3.25 4.00

LGR in Gas Fields
40 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0104

Moderately Folded Anticlines

Monte Carlo Results

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 45,000.00 BCFG

Entire range is from 1,255.51 to 63,464.29 BCFG

After 50,000 trials, the standard error of the mean is 41.76

Statistics: Value

Trials 50000

Mean 19,009.71

Median 17,618.55

Mode ---

Standard Deviation 9,337.52

Variance 87,189,356.52

Skewness 0.66

Kurtosis 3.15

Coefficient of Variability 0.49

Range Minimum 1,255.51

Range Maximum 63,464.29

Range Width 62,208.78

Mean Standard Error 41.76

Frequency Chart

 BCFG

.000

.005

.010

.016

.021

0

259

518

777

1036

0.00 11,250.00 22,500.00 33,750.00 45,000.00

50,000 Trials 418 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 41

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 1,255.51

95% 6,104.18

90% 7,928.95

85% 9,400.52

80% 10,679.85

75% 11,871.99

70% 12,987.12

65% 14,114.07

60% 15,263.74

55% 16,460.96

50% 17,618.55

45% 18,946.60

40% 20,274.97

35% 21,723.27

30% 23,254.13

25% 24,992.24

20% 26,897.35

15% 29,171.50

10% 32,063.93

5% 36,213.79

0% 63,464.29

End of Forecast
42 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 110.00 MMBNGL

Entire range is from 1.58 to 221.24 MMBNGL

After 50,000 trials, the standard error of the mean is 0.11

Statistics: Value

Trials 50000

Mean 40.10

Median 34.90

Mode ---

Standard Deviation 24.37

Variance 593.79

Skewness 1.30

Kurtosis 5.30

Coefficient of Variability 0.61

Range Minimum 1.58

Range Maximum 221.24

Range Width 219.66

Mean Standard Error 0.11

Frequency Chart

 MMBNGL

.000

.006

.012

.018

.024

0

295.5

591

886.5

1182

0.00 27.50 55.00 82.50 110.00

50,000 Trials 830 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 43

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 1.58

95% 10.89

90% 14.41

85% 17.23

80% 19.79

75% 22.27

70% 24.68

65% 27.21

60% 29.64

55% 32.28

50% 34.90

45% 37.69

40% 40.66

35% 44.02

30% 47.80

25% 52.17

20% 57.37

15% 64.18

10% 72.82

5% 87.31

0% 221.24

End of Forecast
44 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 0.00 to 9,000.00 BCFG

Entire range is from 164.41 to 9,998.27 BCFG

After 50,000 trials, the standard error of the mean is 9.30

Statistics: Value

Trials 50000

Mean 3,251.36

Median 2,676.94

Mode ---

Standard Deviation 2,080.60

Variance 4,328,883.48

Skewness 1.12

Kurtosis 3.72

Coefficient of Variability 0.64

Range Minimum 164.41

Range Maximum 9,998.27

Range Width 9,833.86

Mean Standard Error 9.30

Frequency Chart

 BCFG

.000

.006

.013

.019

.025

0

314.7

629.5

944.2

1259

0.00 2,250.00 4,500.00 6,750.00 9,000.00

50,000 Trials 951 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 45

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 164.41

95% 884.32

90% 1,124.30

85% 1,324.58

80% 1,510.40

75% 1,694.27

70% 1,875.41

65% 2,061.57

60% 2,253.34

55% 2,454.85

50% 2,676.94

45% 2,921.37

40% 3,198.93

35% 3,500.60

30% 3,863.52

25% 4,285.15

20% 4,808.16

15% 5,463.40

10% 6,366.80

5% 7,737.20

0% 9,998.27

End of Forecast
46 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 12

Likeliest 51

Maximum 160

Selected range is from 12 to 160

Mean value in simulation was 74

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 232.06 274.06

Standard Deviation 899.03 899.03

Selected range is from 0.00 to 9,958.00 42.00 to 10,000.00

Mean value in simulation was 215.43 257.43

12 49 86 123 160

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 47

Assessment Unit BANG0104

Moderately Folded Anticlines

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 1.00

Likeliest 1.33

Maximum 4.00

Selected range is from 1.00 to 4.00

Mean value in simulation was 2.11

End of Assumptions

Simulation started on 1/25/01 at 20:59:56

Simulation stopped on 1/25/01 at 21:45:11

0.39 2,143.30 4,286.20 6,429.10 8,572.01

Sizes of Gas Fields

1.00 1.75 2.50 3.25 4.00

LGR in Gas Fields
48 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0105

Western Slope

Monte Carlo Results

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 8,000.00 BCFG

Entire range is from 42.72 to 14,809.53 BCFG

After 50,000 trials, the standard error of the mean is 8.59

Statistics: Value

Trials 50000

Mean 2,890.44

Median 2,503.91

Mode ---

Standard Deviation 1,920.48

Variance 3,688,262.62

Skewness 1.03

Kurtosis 4.15

Coefficient of Variability 0.66

Range Minimum 42.72

Range Maximum 14,809.53

Range Width 14,766.81

Mean Standard Error 8.59

Frequency Chart

 BCFG

.000

.005

.010

.015

.020

0

255

510

765

1020

0.00 2,000.00 4,000.00 6,000.00 8,000.00

50,000 Trials 829 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 49

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 42.72

95% 533.84

90% 775.43

85% 979.63

80% 1,180.89

75% 1,386.03

70% 1,590.83

65% 1,809.46

60% 2,030.92

55% 2,263.45

50% 2,503.91

45% 2,757.79

40% 3,035.15

35% 3,331.41

30% 3,646.61

25% 4,004.01

20% 4,414.15

15% 4,911.18

10% 5,538.55

5% 6,536.74

0% 14,809.53

End of Forecast
50 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 20.00 MMBNGL

Entire range is from 0.05 to 49.76 MMBNGL

After 50,000 trials, the standard error of the mean is 0.02

Statistics: Value

Trials 50000

Mean 6.10

Median 4.92

Mode ---

Standard Deviation 4.67

Variance 21.85

Skewness 1.57

Kurtosis 6.59

Coefficient of Variability 0.77

Range Minimum 0.05

Range Maximum 49.76

Range Width 49.72

Mean Standard Error 0.02

Frequency Chart

 MMBNGL

.000

.006

.013

.019

.026

0

324

648

972

1296

0.00 5.00 10.00 15.00 20.00

50,000 Trials 804 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 51

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.05

95% 0.98

90% 1.45

85% 1.86

80% 2.26

75% 2.67

70% 3.08

65% 3.51

60% 3.95

55% 4.42

50% 4.92

45% 5.45

40% 6.03

35% 6.69

30% 7.42

25% 8.25

20% 9.27

15% 10.55

10% 12.35

5% 15.29

0% 49.76

End of Forecast
52 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 0.00 to 2,750.00 BCFG

Entire range is from 42.72 to 4,499.78 BCFG

After 50,000 trials, the standard error of the mean is 3.32

Statistics: Value

Trials 50000

Mean 787.41

Median 545.06

Mode ---

Standard Deviation 742.22

Variance 550,884.28

Skewness 2.11

Kurtosis 8.10

Coefficient of Variability 0.94

Range Minimum 42.72

Range Maximum 4,499.78

Range Width 4,457.06

Mean Standard Error 3.32

Frequency Chart

 BCFG

.000

.009

.017

.026

.035

0

433.5

867

1734

0.00 687.50 1,375.00 2,062.50 2,750.00

50,000 Trials 1,715 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 53

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 42.72

95% 132.46

90% 178.24

85% 219.58

80% 259.36

75% 299.20

70% 342.15

65% 386.61

60% 435.34

55% 486.37

50% 545.06

45% 606.95

40% 676.41

35% 760.01

30% 861.94

25% 986.27

20% 1,149.95

15% 1,378.53

10% 1,730.27

5% 2,377.11

0% 4,499.78

End of Forecast
54 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields

Summary:

Display range is from 0.00 to 8,000.00 BCFG

Entire range is from 0.00 to 14,809.53 BCFG

After 50,000 trials, the standard error of the mean is 9.03

Statistics: Value

Trials 50000

Mean 2,606.15

Median 2,240.91

Mode 0.00

Standard Deviation 2,018.53

Variance 4,074,477.11

Skewness 0.94

Kurtosis 3.90

Coefficient of Variability 0.77

Range Minimum 0.00

Range Maximum 14,809.53

Range Width 14,809.53

Mean Standard Error 9.03

Frequency Chart

 BCFG

.000

.025

.050

.075

.100

0

4982

0.00 2,000.00 4,000.00 6,000.00 8,000.00

50,000 Trials 750 Outliers

Forecast: G-Risked Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 55

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 0.00

95% 0.00

90% 95.26

85% 573.45

80% 829.86

75% 1,052.48

70% 1,275.15

65% 1,499.52

60% 1,736.18

55% 1,985.63

50% 2,240.91

45% 2,508.04

40% 2,790.69

35% 3,105.11

30% 3,441.55

25% 3,800.07

20% 4,223.87

15% 4,746.71

10% 5,387.20

5% 6,401.89

0% 14,809.53

End of Forecast
56 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields

Summary:

Display range is from 0.00 to 20.00 MMBNGL

Entire range is from 0.00 to 49.76 MMBNGL

After 50,000 trials, the standard error of the mean is 0.02

Statistics: Value

Trials 50000

Mean 5.50

Median 4.36

Mode 0.00

Standard Deviation 4.80

Variance 23.01

Skewness 1.48

Kurtosis 6.27

Coefficient of Variability 0.87

Range Minimum 0.00

Range Maximum 49.76

Range Width 49.76

Mean Standard Error 0.02

Frequency Chart

 MMBNGL

.000

.025

.050

.075

.100

0

5021

0.00 5.00 10.00 15.00 20.00

50,000 Trials 719 Outliers

Forecast: G-Risked NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 57

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.00

95% 0.00

90% 0.17

85% 1.06

80% 1.56

75% 2.00

70% 2.45

65% 2.91

60% 3.37

55% 3.86

50% 4.36

45% 4.92

40% 5.52

35% 6.18

30% 6.93

25% 7.78

20% 8.80

15% 10.10

10% 11.90

5% 14.88

0% 49.76

End of Forecast
58 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 1

Likeliest 10

Maximum 55

Selected range is from 1 to 55

Mean value in simulation was 22

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 98.32 140.32

Standard Deviation 408.60 408.60

Selected range is from 0.00 to 4,458.00 42.00 to 4,500.00

Mean value in simulation was 91.60 133.60

1 15 28 42 55

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 59

Assessment Unit BANG0105

Western Slope

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 1.00

Likeliest 1.33

Maximum 4.00

Selected range is from 1.00 to 4.00

Mean value in simulation was 2.11

End of Assumptions

Simulation started on 1/26/01 at 14:12:56

Simulation stopped on 1/26/01 at 14:33:23

0.14 956.10 1,912.06 2,868.02 3,823.99

Sizes of Gas Fields

1.00 1.75 2.50 3.25 4.00

LGR in Gas Fields
60 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0106

Western Platform

Monte Carlo Results

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: Gas in Gas Fields

Summary:

Display range is from 0.00 to 900.00 BCFG

Entire range is from 43.32 to 1,346.56 BCFG

After 50,000 trials, the standard error of the mean is 0.83

Statistics: Value

Trials 50000

Mean 377.61

Median 348.25

Mode ---

Standard Deviation 184.56

Variance 34,063.62

Skewness 0.66

Kurtosis 3.05

Coefficient of Variability 0.49

Range Minimum 43.32

Range Maximum 1,346.56

Range Width 1,303.24

Mean Standard Error 0.83

Frequency Chart

 BCFG

.000

.005

.011

.016

.021

0

263

526

789

1052

0.00 225.00 450.00 675.00 900.00

50,000 Trials 320 Outliers

Forecast: Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 61

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 43.32

95% 125.55

90% 162.36

85% 186.28

80% 210.08

75% 231.98

70% 254.13

65% 276.96

60% 299.76

55% 323.14

50% 348.25

45% 374.94

40% 403.12

35% 433.49

30% 464.13

25% 498.63

20% 537.44

15% 581.77

10% 637.78

5% 718.29

0% 1,346.56

End of Forecast
62 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: NGL in Gas Fields

Summary:

Display range is from 0.00 to 10.00 MMBNGL

Entire range is from 0.27 to 15.99 MMBNGL

After 50,000 trials, the standard error of the mean is 0.01

Statistics: Value

Trials 50000

Mean 3.77

Median 3.39

Mode ---

Standard Deviation 2.03

Variance 4.11

Skewness 0.93

Kurtosis 3.81

Coefficient of Variability 0.54

Range Minimum 0.27

Range Maximum 15.99

Range Width 15.72

Mean Standard Error 0.01

Frequency Chart

 MMBNGL

.000

.006

.012

.017

.023

0

291.2

582.5

873.7

1165

0.00 2.50 5.00 7.50 10.00

50,000 Trials 377 Outliers

Forecast: NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 63

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.27

95% 1.19

90% 1.49

85% 1.76

80% 2.00

75% 2.22

70% 2.44

65% 2.67

60% 2.89

55% 3.14

50% 3.39

45% 3.65

40% 3.93

35% 4.24

30% 4.59

25% 4.97

20% 5.39

15% 5.91

10% 6.60

5% 7.63

0% 15.99

End of Forecast
64 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: Largest Gas Field

Summary:

Display range is from 25.00 to 250.00 BCFG

Entire range is from 43.32 to 399.05 BCFG

After 50,000 trials, the standard error of the mean is 0.22

Statistics: Value

Trials 50000

Mean 109.23

Median 95.63

Mode ---

Standard Deviation 50.14

Variance 2,514.38

Skewness 1.96

Kurtosis 8.14

Coefficient of Variability 0.46

Range Minimum 43.32

Range Maximum 399.05

Range Width 355.73

Mean Standard Error 0.22

Frequency Chart

 BCFG

.000

.008

.015

.023

.031

0

383.5

767

1534

25.00 81.25 137.50 193.75 250.00

50,000 Trials 1,235 Outliers

Forecast: Largest Gas Field
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 65

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: Largest Gas Field (cont'd)

Percentiles:

Percentile BCFG

100% 43.32

95% 58.14

90% 63.45

85% 67.85

80% 71.87

75% 75.60

70% 79.40

65% 83.11

60% 86.95

55% 91.13

50% 95.63

45% 100.56

40% 105.77

35% 111.59

30% 118.43

25% 126.42

20% 136.70

15% 150.65

10% 171.89

5% 209.80

0% 399.05

End of Forecast
66 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields

Summary:

Display range is from 0.00 to 900.00 BCFG

Entire range is from 0.00 to 1,331.72 BCFG

After 50,000 trials, the standard error of the mean is 1.04

Statistics: Value

Trials 50000

Mean 239.89

Median 215.16

Mode 0.00

Standard Deviation 233.28

Variance 54,418.36

Skewness 0.64

Kurtosis 2.52

Coefficient of Variability 0.97

Range Minimum 0.00

Range Maximum 1,331.72

Range Width 1,331.72

Mean Standard Error 1.04

Frequency Chart

 BCFG

.000

.091

.181

.272

.363

0

18147

0.00 225.00 450.00 675.00 900.00

50,000 Trials 183 Outliers

Forecast: G-Risked Gas in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 67

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: G-Risked Gas in Gas Fields (cont'd)

Percentiles:

Percentile BCFG

100% 0.00

95% 0.00

90% 0.00

85% 0.00

80% 0.00

75% 0.00

70% 0.00

65% 0.00

60% 131.85

55% 178.18

50% 215.16

45% 249.69

40% 285.90

35% 321.56

30% 362.66

25% 406.83

20% 454.24

15% 508.14

10% 575.26

5% 666.16

0% 1,331.72

End of Forecast
68 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields

Summary:

Display range is from 0.00 to 9.00 MMBNGL

Entire range is from 0.00 to 14.47 MMBNGL

After 50,000 trials, the standard error of the mean is 0.01

Statistics: Value

Trials 50000

Mean 2.40

Median 2.05

Mode 0.00

Standard Deviation 2.43

Variance 5.88

Skewness 0.85

Kurtosis 3.16

Coefficient of Variability 1.01

Range Minimum 0.00

Range Maximum 14.47

Range Width 14.47

Mean Standard Error 0.01

Frequency Chart

 MMBNGL

.000

.091

.181

.272

.363

0

18147

0.00 2.25 4.50 6.75 9.00

50,000 Trials 551 Outliers

Forecast: G-Risked NGL in Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 69

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Forecast: G-Risked NGL in Gas Fields (cont'd)

Percentiles:

Percentile MMBNGL

100% 0.00

95% 0.00

90% 0.00

85% 0.00

80% 0.00

75% 0.00

70% 0.00

65% 0.00

60% 1.23

55% 1.68

50% 2.05

45% 2.40

40% 2.74

35% 3.13

30% 3.53

25% 3.97

20% 4.48

15% 5.09

10% 5.82

5% 6.97

0% 14.47

End of Forecast
70 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Assumptions

Assumption: Number of Gas Fields

 Triangular distribution with parameters:

Minimum 1

Likeliest 3

Maximum 12

Selected range is from 1 to 12

Mean value in simulation was 5

Assumption: Sizes of Gas Fields

 Lognormal distribution with parameters: Shifted parameters

Mean 28.75 70.75

Standard Deviation 35.80 35.80

Selected range is from 0.00 to 358.00 42.00 to 400.00

Mean value in simulation was 28.35 70.35

1 4 7 9 12

Number of Gas Fields
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 71

Assessment Unit BANG0106

Western Platform

Monte Carlo Results

Assumption: Sizes of Gas Fields (cont'd)

Assumption: LGR in Gas Fields

 Triangular distribution with parameters:

Minimum 5.00

Likeliest 10.00

Maximum 15.00

Selected range is from 5.00 to 15.00

Mean value in simulation was 9.99

End of Assumptions

Simulation started on 1/26/01 at 14:37:16

Simulation stopped on 1/26/01 at 14:50:47

0.99 82.78 164.56 246.35 328.14

Sizes of Gas Fields

5.00 7.50 10.00 12.50 15.00

LGR in Gas Fields
72 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Addendum 2

Assessment Unit Bang0101

Surma Basin

Seventh Approximation Data Form

SEVENTH APPROXIMATION

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/23/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... Surma Basin Number: BANG0101

Based on Data as of:.......... December-00

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S.AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: 0 Gas: 9

 Established (>13 fields) Frontier (1-13 fields) X Hypothetical (no fields)

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (grown) of discovered gas fields (bcfg):

1st 3rd 1309 2nd 3rd 513 3rd 3rd

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 1.0

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 1.0

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 1.0

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

 

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 7 median no. 30 max no. 80

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 95 max. size 10000

IDENTIFICATION INFORMATION
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 73

Assessment Unit (name, no.)

Surma Basin, BANG0101

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 5 10 15

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 1500 3500 5500

 Depth (m) of water (if applicable)...................... 0 0 0
74 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

Surma Basin, BANG0101

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 0

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 75

Assessment Unit Bang0102

Eastern Extremely Folded Belt

Seventh Approximation Data Form

SEVENTH APPROXIMATION

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/24/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... Easternmost Extremely Folded Belt Number: BANG0102

Based on Data as of:.......... 12/1/2000 Petroconsultants

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S.AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: Gas: 0

 Established (>13 fields) Frontier (1-13 fields) Hypothetical (no fields) X

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (grown) of discovered gas fields (bcfg):

1st 3rd 2nd 3rd 3rd 3rd

 

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 1.0

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 0.7

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 0.7

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 1 median no. 7 max no. 15

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 60 max. size 400

IDENTIFICATION INFORMATION
76 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

Easternmost Extremely Folded Belt, BANG0102

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 0.5 1 2

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 1500 3000 4500

 Depth (m) of water (if applicable)...................... 0 0 0
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 77

Assessment Unit (name, no.)

Easternmost Extremely Folded Belt, BANG0102

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 0

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
78 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0103

High-Amplitude Faulted Anticlines

Seventh Approximation Data Form

SEVENTH APPROXIMATION

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/24/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... High-Amplitude Faulted Anticlines Number: BANG0103

Based on Data as of:.......... 12/1/2000 Petroconsultants

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S.AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: 0 Gas: 1

 Established (>13 fields) Frontier (1-13 fields) X Hypothetical (no fields)

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (known) of discovered gas fields (bcfg):

1st 3rd 98 2nd 3rd 3rd 3rd

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 1.0

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 1.0

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 1.0

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 2 median no. 15 max no. 35

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 70 max. size 2000

IDENTIFICATION INFORMATION
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 79

Assessment Unit (name, no.)

High Amplitude Faulted Anticlines, BANG0103

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 1 2 4

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 1500 3000 4500

 Depth (m) of water (if applicable)...................... 0 0 3
80 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

High Amplitude Faulted Anticlines, BANG0103

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 0

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 81

Assessment Unit Bang0104

Moderately Folded Anticlines

Seventh Approximation Data Form

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/25/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... Moderately Folded Anticlines Number: BANG0104

Based on Data as of:.......... 12/1/2000 Petroconsultants

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S. AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: 0 Gas: 9

 Established (>13 fields) Frontier (1-13 fields) X Hypothetical (no fields)

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (grown) of discovered gas fields (bcfg):

1st 3rd 468 2nd 3rd 237 3rd 3rd

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 1.0

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 1.0

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 1.0

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 12 median no. 70 max no. 160

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 100 max. size 10000

IDENTIFICATION INFORMATION
82 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

 Moderately Folded Anticlines, BANG0104

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 1 2 4

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 2500 3500 5000

 Depth (m) of water (if applicable)...................... 0 20 200
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 83

Assessment Unit (name, no.)

Moderately Folded Anticlines, BANG0104

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 40

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
84 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit Bang0105

Western Slope

Seventh Approximation Data Form

Seventh Approximation

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/25/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... Western Slope Number: BANG0105

Based on Data as of:.......... 12/1/2000 Petrobangla

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S. AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: Gas: 0

 Established (>13 fields) Frontier (1-13 fields) Hypothetical (no fields) X

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (grown) of discovered gas fields (bcfg):

1st 3rd 2nd 3rd 3rd 3rd

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 1.0

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 0.9

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 0.9

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 1 20 55

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 65 max. size 4500

IDENTIFICATION INFORMATION
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 85

Assessment Unit (name, no.)

Western Slope, BANG0105

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 1 2 4

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 2500 3500 5000

 Depth (m) of water (if applicable)...................... 0 20 200
86 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

Western Slope, BANG0105

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 45

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 87

Assessment Unit Bang0106

Western Platform

Seventh Approximation Data Form

SEVENTH APPROXIMATION

DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS (Version 2, 10-5-00)

Date:................................ 1/26/2001

Assessment Geologist:........ Petrobangla/USGS

Region:............................. South Asia Number: 8

Province:........................... Country of Bangladesh Number:

Priority or Boutique............. Special

Total Petroleum System:...... Tertiary Composite Number: BANG01

Assessment Unit:............... Western Platform Number: BANG0106

Based on Data as of:.......... 12/1/2000 Petrobangla

* Notes from Assessor 1/96 Petroconsultants and Proprietary Data from IOC. Special joint 

assessment sponsered by U.S. AID. No growth function used.

CHARACTERISTICS OF ASSESSMENT UNIT

Oil (<20,000 cfg/bo overall) or Gas (>20,000 cfg/bo overall):... Gas

What is the minimum field size?.......... 7 mmboe grown

(the smallest field that has potential to be added to reserves in the next 30 years)

Number of discovered fields exceeding minimum size:............ Oil: Gas: 0

 Established (>13 fields) Frontier (1-13 fields) Hypothetical (no fields) X

Median size (grown) of discovered oil fields (mmboe):

1st 3rd 2nd 3rd 3rd 3rd

Median size (grown) of discovered gas fields (bcfg):

1st 3rd 2nd 3rd 3rd 3rd

Assessment-Unit Probabilities:

 Attribute Probability of occurrence (0-1.0)

1. CHARGE: Adequate petroleum charge for an undiscovered field > minimum size.................. 0.8

2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size...... 0.8

3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size 1.0

Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3):........................ 0.64

4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field

 > minimum size...................................................................................................... 1.0

UNDISCOVERED FIELDS

Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: 

 (uncertainty of fixed but unknown values)

Oil fields:.......................................min. no. (>0) median no. max no.

Gas fields:.....................................min. no. (>0) 1 median no. 5 max no. 12

Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: 

 (variations in the sizes of undiscovered fields)

Oil in oil fields (mmbo)..........................min. size median size max. size

Gas in gas fields (bcfg):........................min. size 42 median size 60 max. size 400

IDENTIFICATION INFORMATION
88 Petroleum Systems and Related Geologic Studies in Region 8, South Asia

Assessment Unit (name, no.)

Western Platform, BANG0106 

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)

Oil Fields: minimum median maximum

 Gas/oil ratio (cfg/bo).......................................

 NGL/gas ratio (bngl/mmcfg).............................

Gas fields: minimum median maximum

 Liquids/gas ratio (bngl/mmcfg).......................... 5 10 15

 Oil/gas ratio (bo/mmcfg)..................................

SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS

(variations in the properties of undiscovered fields)

Oil Fields: minimum median maximum

 API gravity (degrees)......................................

 Sulfur content of oil (%)...................................

 Drilling Depth (m) ..........................................

 Depth (m) of water (if applicable).......................

Gas Fields: minimum median maximum

 Inert gas content (%)...................................... 0.1 0.4 0.9

 CO2 content (%)............................................ 0.1 0.4 1

 Hydrogen-sulfide content (%)............................ 0 0 0

 Drilling Depth (m).......................................... 2000 3500 4500

 Depth (m) of water (if applicable)...................... 0 0 0
U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh 89

Assessment Unit (name, no.)

Western Platform, BANG0106 

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

TO COUNTRIES OR OTHER LAND PARCELS (uncertainty of fixed but unknown values)

1. Bangladesh represents 100 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):... 100

 Portion of volume % that is offshore (0-100%)...... 0

2. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

3. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

4. represents areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......

Gas in Gas Fields: minimum median maximum

 Richness factor (unitless multiplier):..................

 Volume % in parcel (areal % x richness factor):...

 Portion of volume % that is offshore (0-100%)......
Surma Basin, Assessment Unit BANG0101 Known Data First half of accumulations discovered Second half of accumulations discovered Total 

Mean 1253.4 Mean 898 Mean Standard Error 446.5349482 Standard Error 522.0630549 StandMedian 1309 Median 512.5 MediaMode #N/A Mode #N/A Mode Standard Deviation 998.4824986 Standard Deviation 1044.12611 StandSample Variance 996967.3 Sample Variance 1090199.333 SampKurtosis -2.075983648 Kurtosis 2.203364998 Kurto

Skewness 0.175956331 Skewness 1.564704407 SkewRange 2263 Range 2233 RangMinimum 266 Minimum 167 MinimMaximum 2529 Maximum 2400 MaximSum 6267 Sum 3592 Sum Count 5 Count 4 CounNumber of Years 8 Number of Years 35 NumbFirst Year of First Half or First Third Last Year of First Half or First Third First Year of Second Half or Second Third Last Year of Second Half or Second Third

1955 1963 1981 1998
Surma Basin, Assessment Unit BANG0101

02468

101214

1920 1930 1940 1950 1960 1970 1980 19

DRILLING-COMPLETION YEAR

CUM. NEW-FIELD WILDCAT WELLS (No.)
Surma Basin, Assessment Unit BANG0101

0123

1923

1926

1929

1932

1935

1938

1941

1944

1947

1950

1953

1956

1959

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

DRILLING-COMPLETION YEAR

NEW-FIELD WILDCAT WELLS (No.)
Surma Basin, Assessment Unit BANG0101

1

10

100

1,000

10,000

100,000

0123456

GAS-ACCUMULATION RANK BY SIZE

KNOWN GAS-ACCUMULATION SIZE (BCFG) First half of accumul

Second half of accudiscovered
Surma Basin, Assessment Unit BANG0101

01234

6 to <12

12 to <24

24 to <48

48 to <96

96 to <192

192 to <384

384 to <768

768 to <1,536

1,536 to <3,072

3,072 to <6,144

6,144 to <12,288

12,288 to <24,576

24,576 to <49,152

49,152 to <98,304

98,304 to <196,608

196,608 to <393,216

393,216 to <786,432

786,432 to <1,572,864

>=1,572,864

KNOWN GAS-ACCUMULATION SIZE (BCFG)

GAS ACCUMULATIONS (No.) Second half of accu

discovered First half of accumul
Surma Basin, Assessment Unit BANG0101

0

1,0002,0003,0004,0005,0006,0007,0008,000

6 to <12

12 to <24

24 to <48

48 to <96

96 to <192

192 to <384

384 to <768

768 to <1,536

1,536 to <3,072

3,072 to <6,144

6,144 to <12,288

12,288 to <24,576

24,576 to <49,152

49,152 to <98,304

98,304 to <196,608

196,608 to <393,216

393,216 to <786,43

786,432 to 

KNOWN GAS-ACCUMULATION SIZE (BCFG)

VOLUME OF GAS (BCFG)
Surma Basin, Assessment Unit BANG0101

1

10

100

1,000

10,000

100,000

1920 1930 1940 1950 1960 1970 1980 1

ACCUMULATION-DISCOVERY YEAR

KNOWN GAS-ACCUMULATION SIZE (BCFG)
Surma Basin, Assessment Unit BANG0101

1

10

100

1,000

10,000

100,000

0 2 4 6 8 10 1

CUM. NEW-FIELD WILDCAT WELLS (No.)

KNOWN GAS-ACCUMULATION SIZE (BCFG)
Surma Basin, Assessment Unit BANG0101

0

2,0004,0006,0008,000

10,00012,000

1920 1930 1940 1950 1960 1970 1980 1

ACCUMULATION-DISCOVERY YEAR

CUM. KNOWN GAS VOLUME (BCFG)
Surma Basin, Assessment Unit BANG0101

0

2,0004,0006,0008,000

10,00012,000

0 2 4 6 8 10 1

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. KNOWN GAS VOLUME (BCFG)
Surma Basin, Assessment Unit BANG0101

0123456789

10

1920 1930 1940 1950 1960 1970 1980 19

ACCUMULATION-DISCOVERY YEAR

CUM. GAS ACCUMULATIONS (No.)
Surma Basin, Assessment Unit BANG0101

0123456789

10

0 2 4 6 8 10 1

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. GAS ACCUMULATIONS (No.)
Surma Basin, Assessment Unit BANG0101

0

500

1,0001,5002,0002,5003,0003,5004,000

1920 1930 1940 1950 1960 1970 1980 1

RESERVOIR-DISCOVERY YEAR

RESERVOIR DEPTH, GAS ACCUMULATIONS 

(ft)
Surma Basin, Assessment Unit BANG0101

0

500

1,0001,5002,0002,5003,0003,5004,000

0 2 4 6 8 10 

CUM. NEW-FIELD WILDCAT WELLS (No.)

RESERVOIR DEPTH, GAS ACCUMULATIONS 

(ft)
Surma Basin, Assessment Unit BANG0101

05

10152025

0 500 1,000 1,500 2,000 2,500 3,000 3,

MEAN RESERVOIR DEPTH (ft)

LIQUIDS/GAS, GAS ACCUMULATIONS 

(BL/MMCFG)
Moderately Folded Anticlines, Assessment Unit BANG0104

Known Data

First half of accumulations discovered Second half of accumulations discovered Total Mean 599.6666667 Mean 310.2 Mean Standard Error 328.6077364 Standard Error 140.5640068 StandMedian 296.5 Median 140 MediaMode #N/A Mode #N/A Mode Standard Deviation 804.9212798 Standard Deviation 314.3106743 StandSample Variance 647898.2667 Sample Variance 98791.2 Samp

Kurtosis 2.672524398 Kurtosis 3.20062181 KurtoSkewness 1.66565334 Skewness 1.819735516 SkewRange 2085 Range 744 RangMinimum 15 Minimum 104 MinimMaximum 2100 Maximum 848 MaximSum 3598 Sum 1551 Sum Count 6 Count 5 Count Number of Years 20 Number of Years 14 NumbFirst Year of First Half or First Third Last Year of First Half or First Third First Year of Second Half or Second Third Last Year of Second Half or Second Third

1962 1982 1990 1996
Moderately Folded Anticlines, Assessment Unit BANG010

02468

101214161820

1955 1960 1965 1970 1975 1980 1985 1990 

DRILLING-COMPLETION YEAR

CUM. NEW-FIELD WILDCAT WELLS (No.)
Moderately Folded Anticlines, Assessment Unit BANG01

0123456

1958

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

DRILLING-COMPLETION YEAR

NEW-FIELD WILDCAT WELLS (No.)
Moderately Folded Anticlines, Assessment Unit BANG010

1

10

100

1,000

10,000

01234567

GAS-ACCUMULATION RANK BY SIZE

KNOWN GAS-ACCUMULATION SIZE (BCFG) First half of accumul

Second half of accudiscovered
Moderately Folded Anticlines, Assessment Unit BANG010

012345

6 to <12

12 to <24

24 to <48

48 to <96

96 to <192

192 to <384

384 to <768

768 to <1,536

1,536 to <3,072

3,072 to <6,144

6,144 to <12,288

12,288 to <24,576

24,576 to <49,152

49,152 to <98,304

98,304 to <196,608

196,608 to <393,216

393,216 to <786,432

786,432 to <1,572,864

>=1,572,864

KNOWN GAS-ACCUMULATION SIZE (BCFG)

GAS ACCUMULATIONS (No.) Second half of accu

discovered First half of accumul
Moderately Folded Anticlines, Assessment Unit BANG01

0

500

1,0001,5002,0002,500

6 to <12

12 to <24

24 to <48

48 to <96

96 to <192

192 to <384

384 to <768

768 to <1,536

1,536 to <3,072

3,072 to <6,144

6,144 to <12,288

12,288 to <24,576

24,576 to <49,152

49,152 to <98,304

98,304 to <196,608

196,608 to <393,216

393,216 to <786,43

786,432 to 

KNOWN GAS-ACCUMULATION SIZE (BCFG)

VOLUME OF GAS (BCFG)
Moderately Folded Anticlines, Assessment Unit BANG010

1

10

100

1,000

10,000

1955 1960 1965 1970 1975 1980 1985 1990 

ACCUMULATION-DISCOVERY YEAR

KNOWN GAS-ACCUMULATION SIZE (BCFG)
Moderately Folded Anticlines, Assessment Unit BANG010

1

10

100

1,000

10,000

0 2 4 6 8 10 12 14 16 

CUM. NEW-FIELD WILDCAT WELLS (No.)

KNOWN GAS-ACCUMULATION SIZE (BCFG)
Moderately Folded Anticlines, Assessment Unit BANG010

0

1,0002,0003,0004,0005,0006,000

1955 1960 1965 1970 1975 1980 1985 1990 

ACCUMULATION-DISCOVERY YEAR

CUM. KNOWN GAS VOLUME (BCFG)
Moderately Folded Anticlines, Assessment Unit BANG010

0

1,0002,0003,0004,0005,0006,000

0 2 4 6 8 10 12 14 16 

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. KNOWN GAS VOLUME (BCFG)
Moderately Folded Anticlines, Assessment Unit BANG010

02468

1012

1955 1960 1965 1970 1975 1980 1985 1990 

ACCUMULATION-DISCOVERY YEAR

CUM. GAS ACCUMULATIONS (No.)
Moderately Folded Anticlines, Assessment Unit BANG010

02468

1012

0 2 4 6 8 10 12 14 16 

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. GAS ACCUMULATIONS (No.)
Moderately Folded Anticlines, Assessment Unit BANG010

0

500

1,0001,5002,0002,5003,0003,500

1955 1960 1965 1970 1975 1980 1985 1990 

RESERVOIR-DISCOVERY YEAR

RESERVOIR DEPTH, GAS ACCUMULATIONS 

(ft)
Moderately Folded Anticlines, Assessment Unit BANG010

0

500

1,0001,5002,0002,5003,0003,500

0 2 4 6 8 10 12 14 16 

CUM. NEW-FIELD WILDCAT WELLS (No.)

RESERVOIR DEPTH, GAS ACCUMULATIONS 

(ft)
Moderately Folded Anticlines, Assessment Unit BANG010

0123

0 500 1,000 1,500 2,000 2,500 3,00

MEAN RESERVOIR DEPTH (ft)

LIQUIDS/GAS, GAS ACCUMULATIONS 

(BL/MMCFG)