al Petroleum System

Shabwah, and

men

202-G

Gulf of Aden

nd code

Madbi Amran/Qishn Total Petroleum System outline

Assessment unit outline

Source rock outline

Location of thermal modeling (fig. 14)

EXPLANATION

0 100 KILOMETERS

2009

2006

2010

2007

asila-Jeza Basin

Shabwah

Basin

in

Sharmah Rift Basin

Ghudun-Khasfeh Flank Province

BIA

Haru

Sunah

Tawila Heijah

Nazaih Camaal

Kharir

Hemiar

Mintaq 1

graf 1

ast

Hemiar West 

wah 1

Camaal North

Hemiar South

Hemiar North

Wadi Taribah

Qarn Qaymah 1

Atuf Northwest

Sunah Northeast

Husn El Kradis 1

Mukalla

Mukalla High
Madbi Amran / Qishn Total Petroleum System 

of the Ma′Rib–Al Jawf / Shabwah, and 

Masila-Jeza Basins, Yemen 

By Thomas S. Ahlbrandt 

U.S. Geological Survey Bulletin 2202-G 

U.S. Department of the Interior 

U.S. Geological Survey 
U.S. Department of the Interior 

Gale A. Norton, Secretary 

U.S. Geological Survey 

Charles G. Groat, Director 

This publication is only available online at: 

http://geology.cr.usgs.gov/pub/bulletins/b2202-g/ 

Version 1.0 2002 

Any use of trade, product, or firm names in this publication
 

is for descriptive purposes only and
 

does not imply endorsement by the U.S. Government
 

Published in the Central Region, Denver, Colorado
 

Manuscript approved for publication April 4, 2002
 

Graphics by author and Gayle M. Dumonceaux
 

Photocomposition by Gayle M. Dumonceaux
 

Edited by L.M. Carter
 
Contents 

Foreword ........................................................................................................................................ 1
 

Abstract .......................................................................................................................................... 1
 

Introduction.................................................................................................................................... 2
 

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

Province Geology.......................................................................................................................... 2
 

Province Boundaries ......................................................................................................... 2
 

Geographic Setting ............................................................................................................ 2
 

Political and Exploration History ..................................................................................... 2
 

Geologic Setting ................................................................................................................. 6
 

Total Petroleum System............................................................................................................... 7
 

Petroleum Occurrence...................................................................................................... 7
 

Source Rock and Oil .......................................................................................................... 15
 

Reservoir Rock.................................................................................................................... 18
 

Seal Rock............................................................................................................................. 21
 

Overburden Rock................................................................................................................ 21
 

Hypothetical Total Petroleum Systems .......................................................................... 21
 

Petroleum Assessment ................................................................................................................ 22
 

References Cited........................................................................................................................... 27
 

Figures 

1–3. Maps showing: 

1.	 Geologic provinces, Madbi Amran/Qishn Total Petroleum System,
 

assessment unit, and major petroleum basins in and adjacent to Yemen ....... 3
 

2.	 Location of cross sections, selected well locations, administrative
 

provinces, and areas of dune sand of Yemen ....................................................... 4
 

3.	 Structural elements including basins, highs, faults, and outcrop belts,
 

and cross section locations...................................................................................... 5
 

4. Cross section A–B across western and central portions of Yemen ........................ 8
 

5. Cross section B–C across central and eastern Yemen............................................... 9
 

6–10.	 Charts showing lithostratigraphy, correlations, and spatial stratigraphic 

distributions for: 

6. Phanerozoic rocks in Yemen .................................................................................... 10
 

7. Paleozoic rocks in Yemen and adjacent Saudi Arabia ........................................ 11
 

8. Jurassic rocks in Yemen ........................................................................................... 12
 

9. Cretaceous rocks in Yemen ...................................................................................... 13
 

10. Cenozoic rocks in Yemen, Oman, and Saudi Arabia............................................. 14
 

11.	 Schematic diagram of total petroleum systems in Ma′Rib–Al Jawf/
 

Shabwah and Masila-Jeza basins, Yemen.................................................................... 16
 

III


12.	 Tectono-stratigraphic, halokinetic, and petroleum generation history model
 

of Ma′Rib–Al Jawf/Shabwah basin, western Yemen .................................................. 17
 

13.	 Tectono-stratigraphic and petroleum generation model of Masila-Jeza
 

basin, eastern Yemen........................................................................................................ 18
 

14.	 Thermal maturation modeling for Ma′Rib–Al Jawf/Shabwah basin,
 

western Yemen .................................................................................................................. 19
 

15.	 Petroleum system events chart for Madbi Amran/Qishn Total Petroleum
 

System, Yemen ................................................................................................................... 20
 

16.	 Graph showing cumulative grown oil volumes versus discovery year for
 

Yemen assessment unit .................................................................................................... 23
 

17.	 Graph showing cumulative grown gas volumes versus discovery year for
 

Yemen assessment unit ................................................................................................... 24
 

18.	 Histogram showing estimated undiscovered oil field number and size
 

distribution for Madbi Amran/Qishn Total Petroleum System, Yemen ..................... 25
 

19.	 Histogram showing estimated undiscovered oil field number and size
 

distribution for Madbi Amran/Qishn Total Petroleum System, Yemen ..................... 26
 

IV


Madbi Amran / Qishn Total Petroleum System 

of the Ma′Rib–Al Jawf / Shabwah, and 

Masila-Jeza Basins, Yemen 

By Thomas S. Ahlbrandt 

Foreword 

This report, describing the petroleum resources of a total 

petroleum system in Yemen, was prepared as part of the World 

Energy Assessment Project of the U.S. Geological Survey. For 

this project, the world was divided into 8 regions and 937 geologic provinces, which were then ranked according to the discovered oil and gas volumes within each (Klett and others, 

1997). Of these, 76 “priority” provinces (exclusive of the U.S. 

and chosen for their high ranking) and 52 “boutique” provinces 

(exclusive of the U.S. and chosen for their anticipated petroleum 

richness or special regional economic importance) were selected 

for appraisal of oil and gas resources. The petroleum geology of 

these priority and boutique provinces is described in this series 

of reports. 

The purpose of the World Energy Project is to assess the 

quantities of oil, gas, and natural gas liquids that have the potential to be added to reserves within the next 30 years. These volumes either reside in undiscovered fields whose sizes exceed the 

stated minimum-field-size cutoff value for the assessment unit 

(variable, but must be at least 1 million barrels of oil equivalent) 

or occur as reserve growth of fields already discovered. 

The total petroleum system constitutes the basic geologic 

unit of the oil and gas assessment. The total petroleum system 

includes all genetically related petroleum that occurs in shows 

and accumulations (discovered and undiscovered) that (1) has 

been generated by a pod or by closely related pods of mature 

source rock, and (2) exists within a limited mappable geologic 

space, along with the other essential mappable geologic elements (reservoir, seal, and overburden rocks) that control the 

fundamental processes of generation, expulsion, migration, 

entrapment, and preservation of petroleum. The minimum 

petroleum system is that part of a total petroleum system encompassing discovered shows and accumulations along with the 

geologic space in which the various essential elements have 

been proved by these discoveries. 

An assessment unit is a mappable part of a total petroleum 

system in which discovered and undiscovered fields constitute a 

single, relatively homogeneous population such that the chosen 

methodology of resource assessment based on estimation of the 

number and sizes of undiscovered fields is applicable. A total 

petroleum system may equate to a single assessment unit, or it 

may be subdivided into two or more assessment units if each 

unit is sufficiently homogeneous in terms of geology, exploration considerations, and risk to assess individually. 

A graphical depiction of the elements of a total petroleum 

system is provided in the form of an events chart that shows the 

times of (1) deposition of essential rock units; (2) trap formation; (3) generation, migration, and accumulation of hydrocarbons; and (4) preservation of hydrocarbons. 

A numeric code identifies each region, province, total 

petroleum system, and assessment unit; these codes are uniform 

throughout the project and will identify the same type of entity 

in any of the publications. The code is as follows: 

Example 

Region, single digit 2 

Province, three digits to the right of region code 2004 

Total petroleum system, two digits to the right of 

province code 200401 

Assessment unit, two digits to the right of petroleum 

system code 20040101 

The codes for the regions and provinces are listed in Klett and 

others (1997). 

Oil and gas reserves quoted in this report are derived from 

Petroconsultants’ Petroleum Exploration and Production database (Petroconsultants, 1996) and other area reports from Petroconsultants, Inc., unless otherwise noted. 

Figure(s) in this report that show boundaries of the total 

petroleum system(s), assessment units, and pods of active 

source rocks were compiled using geographic information system (GIS) software. Political boundaries and cartographic representations were taken, with permission, from Environmental 

Systems Research Institute’s ArcWorld 1:3 million digital coverage (1992), have no political significance, and are displayed 

for general reference only. Oil and gas field centerpoints, shown 

in these figures, are reproduced, with permission, from Petroconsultants, 1996. 

Abstract 

Since the first discovery of petroleum in Yemen in 1984, 

several recent advances have been made in the understanding of 

that country’s geologic history and petroleum systems. The 

total petroleum resource endowment for the combined 

petroleum provinces within Yemen, as estimated in the recent 

U.S. Geological Survey world assessment, ranks 51st in the 

world, exclusive of the United States, at 9.8 BBOE, which 

includes cumulative production and remaining reserves, as well 

1
 
as a mean estimate of undiscovered resources. Such undiscovered petroleum resources are about 2.7 billion barrels of oil, 17 

trillion cubic feet (2.8 billion barrels of oil equivalent) of natural 

gas and 1 billion barrels of natural gas liquids. A single total 

petroleum system, the Jurassic Madbi Amran/Qishn, dominates 

petroleum generation and production; it was formed in response 

to a Late Jurassic rifting event related to the separation of the 

Arabian Peninsula from the Gondwana supercontinent. This 

rifting resulted in the development of two petroleum-bearing 

sedimentary basins: (1) the western Ma’Rib–Al Jawf / Shabwah 

basin, and (2) the eastern Masila-Jeza basin. In both basins, 

petroleum source rocks of the Jurassic (Kimmeridgian) Madbi 

Formation generated hydrocarbons during Late Cretaceous time 

that migrated, mostly vertically, into Jurassic and Cretaceous 

reservoirs. In the western Ma’Rib–Al Jawf / Shabwah basin, the 

petroleum system is largely confined to syn-rift deposits, with 

reservoirs ranging from deep-water turbidites to continental 

clastics buried beneath a thick Upper Jurassic (Tithonian) salt. 

The salt initially deformed in Early Cretaceous time, and continued halokinesis resulted in salt diapirism and associated salt 

withdrawal during extension. The eastern Masila-Jeza basin 

contained similar early syn-rift deposits but received less clastic 

sediment during the Jurassic; however, no salt formed because 

the basin remained open to ocean circulation in the Late Jurassic. Thus, Madbi Formation-sourced hydrocarbons migrated 

vertically into Lower Cretaceous estuarine, fluvial, and tidal 

sandstones of the Qishn Formation and were trapped by overlying impermeable carbonates of the same formation. Both basins 

were formed by extensional forces during Jurassic rifting; however, another rifting event that formed the Red Sea and Gulf of 

Aden during Oligocene and Miocene time had a strong effect on 

the eastern Masila-Jeza basin. Recurrent movement of basement 

blocks, particularly during the Tertiary, rather than halokinesis, 

was critical to the formation of traps. 

Introduction 

This report describes the total petroleum system (TPS), the 

Jurassic Madbi Amran / Qishn of the Ma’Rib–Al Jawf Basin 

(2004), Shabwah Basin (2006), and Masila-Jeza Basin (2009) 

provinces (fig. 1). The estimated undiscovered resources of the 

TPS are all contained within the country of Yemen. In terms of a 

political entity, Yemen is a relatively young country; and it is 

also a recent petroleum-producing area, with the first petroleum 

discovery of oil at Alif field in 1984 (fig. 1). Of the world’s 409 

geologic provinces that contain hydrocarbons, 3 such provinces 

are in Yemen and are combined into one total petroleum system 

with a ranking of total petroleum endowment of 51st in the 

world. The total petroleum endowment of this TPS is an estimated 9.8 BBOE (billion barrels of oil equivalent) (Ahlbrandt 

and others, 2000), and with a production of about 405,800 

BOPD (barrels of oil per day) from this TPS (International 

Petroleum Encyclopedia, 2000), Yemen is now recognized as a 

significant petroleum-producing country. The geologic understanding of Yemen in the last two decades, particularly the last 

10 years, has been substantially improved, causing an essentially 

unexplored area to become an important petroleum-producing 

area in a relatively short time. 

Acknowledgments 

This paper benefited from discussions with Dr. David 

Boote, Occidental Oil Company, and other members of the 

World Energy Consortium, an advisory group to the World 

Energy Project. Reserves data are derived from Petroconsultants 

(1996) and oil data are derived from GeoMark (1998). The Oil 

and Gas Journal and Dr. Istvan Csato of MOL Hungarian Oil 

Company gave permission for use of selected figures in this 

report that is much appreciated. Richard Pollastro and Timothy 

Klett reviewed the manuscript and made many helpful 

suggestions. 

Province Geology 

Province Boundaries 

Yemen is located in the southwestern portion of the Arabian Peninsula, bordered by the Red Sea to the west, the Gulf of 

Aden to the south, and the Arabian Sea to the east. It shares a 

common border with Oman on the east and a disputed border 

with Saudi Arabia on the north (fig. 2). Yemen is divided into 10 

geologic provinces by the USGS, 3 of which contain petroleum 

(Klett and others, 1997). These three provinces are Ma’Rib–Al 

Jawf Basin (2004), Shabwah Basin (2006), and Masila-Jeza 

Basin (2009) (fig. 1). One total petroleum system, the Madbi 

Amran / Qishn, encompasses the hydrocarbon potential of 

Yemen and crosses these three petroleum province boundaries 

(fig. 1). Subsequently, the geologic understanding of the area 

permitted combining the three provinces into two basins as 

described in the total petroleum system section. 

Geographic Setting 

Yemen is bounded by 1,900 km (kilometers) of coastline of 

the Red Sea along its western border and the Gulf of Aden at its 

southern border. A narrow coastal plain adjacent to a mountainous Precambrian terrane to the west gives way to a dissected 

upland desert plain to the east and merges into the great deserts 

of the Rub’Al Khali farther to the north and east (figs. 2, 3). The 

climate ranges from hot and humid in the west to extraordinarily 

hot in the deserts to the northeast. 

The area of Yemen is 527,970 km2, about twice the size of 

the State of Wyoming. Yemen claims a 200-nautical mile (or to 

the edge of the continental shelf) exclusive economic zone. 

Political and Exploration History 

Politically, Yemen had been divided into two countries— 

Northern Yemen (the Yemen Arab Republic, YAR), and South 

Yemen (the former Aden Protectorate and later the People’s 

Democratic Republic of Yemen, PDRY)—until 1990 when 

they were united to form the Republic of Yemen. North 

2 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 
45°E 

Geologic province and code 

Gas field 

Madbi Amran/Qish

Assessment unit ou

Oil field Source rock outline

EXPLANATION 

0 

2101 

2004 

2006 

2005 

2002 

201

2019 

2101 

2001 

Masila-Jeza Basin 

Arabian Shield 

Shabwah 

Basin 

Mukalla Rift Basin 

Ma'Rib-Al 

Jawf Basin 

Rub' Al Khali Basin 

Hays Structural Belt

Yemen Volcanic Basin (South) 

Ghudun-Khasfe

Red Sea Basin 

Yemen V

olcanic 

Basin (North) 

Aden 

Sanaa 

YEMEN 

SAUDI

Amal 

Alif 

Azal 

Meem 

Lam 1 

Yah 1 

Aser 1 

H

Camaal 

Kharir 

Raydan 

Nakaa 1 

Mawza 1 

Balquis 

Kamaran 

Mintaq 1 

Magraf 1 

Rajwan 1 

Dhahab 1 

Shaharah 

Al-Shura 

Suqatrah 

Ma'een 1 Ayad East 

Ayad West 

Al Nasr 1 

Al-Wihdah 

Al-Saidah 

Wadi Bana 

Al Khair 1 

Al-Tahreer 

Jabal Habah Jabal Nuqum 

Jabal Ras 1 

Al Kharwah 1 

Camaal North 

W

Jabal Barat 1 

Jabal Samadan 

Qarn Qaymah 1 

Saif Bin Yazen 

Atuf Northwest 

As'ad al-Kamil 

Halewah-Sabatayn 

Al-Raja - Jannah 

Husn El Kradis 1 

Dostour Al-Wahdah 

15° 

Muk

Taiz 

Mukalla High 

ARABIA 

Province Geology Country boundary INDEX MAP City Location of therma

Figure 1. Geologic provinces, Madbi Amran/Qishn Total Petroleum System, assessment unit, and major petroleum basins in and adja

3

4
 

30°

Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 

16° 

15° 

Rub' Al Khali Sand Desert (Empty Quarter) 

43°E 45°E 47°E 49°E 

D i s p u t e d 

B o r d e r D i s p u t e d 

B o r d e r 

H 

i 

g 

h 

P l a t e 

a 

u 

D i s p u t e d 

B 

C 

A 

A l Y D A H 

A B Y A N 

S H A B W A H

M A ' R I B 

L A H E J 

T A' I Z 

D A M A R 

H A J J A H 

S A ' D A H 

Al Meethaq-2 

Al Meethaq-1

Jizan 

Kamaran I sl. 

Kathib-1 

H 

U D A I D A H 

Hodaidah 1 & 2 

Hufayr-1 

Balhaf-1 

Ash Shuaib-1 

Al-Kharaj-1 

NaKaah-1 

Raydan-1 Lam-1 Bilquin-1 

Yah-1 

Neem-1 

J. A

y ban-1 

Al Masbafl-1 Thukmayn-1 

R 

E 

D 

S

E 

A 

ST Al-1 

Azal-1 

S A N A A 

Jambiyah-1 

G U L F O F A D E N 

Kharwah +Kharwah-1 

Shaja-1 

Sinwah-1 

Kamaran-1 

Himyar-1 

Arwa-1 

Saba-1 

Khaywan-1 

Abbas-1 Zaydiya-1 

Salif 

Balhaf-2 

Hami-1 

Sharmah-1 

H A D R A M A W T 

M A 

Al-Qarn-1 

Maljan-1 

Ghayl Bin Yammin-1 

Howarim-1 

Sunah-1 

Camaal-1

Hatho

Qinab-1 H

Ta

Armah-1 

Al-Furt-1 

Wadi-Jeza-1 

1

Thamud-1 

Al Auch 

Ras Ghashwah-1 Sarar-1 

Qus.-1 

Masilah-1 

S A U D I 

A R A B I A 

Aden 

Ta'iz 

Sanaa 

Alif-1 Ma'een-1 

Beta-1 

A D E N 

IBB 

Al Hudaydah 

Mukalla 

Farasan Isls 

Perim Isl. 

Say'un 

Eg

S

15° 

B o r d e r 

B A 

14° 

13° 

45° 47° 49° 51° 

EXPLANATION 

Well Boundaries between administrative provinces Cities and towns International border (demarcated) Dune sand International border (disputed) 

Figure 2. Location of cross sections (in red), selected well locations, administrative provinces, and areas of dune sand of Yemen (modified from 
42°E 44°E 46°E 48°E 50°E 

? 

Sunah-1 

Maljan-1 

Sarar-1 

Hadramawt 

Arch 

Qinab-1 

Hathouth-1

Hatho

0 

RED SEA (J3) SANAA 

TA'IZ 

Abas Gneiss 

Terrane 

1.7-2.3 Ga 

W. Siham Central (Mahfid) 

Uplift 

Aden 

Ad Dali' Basin 

Jani-Mukalla High 

Rub'

Al Khali Basin (Southern Flank) 

SAY'UN 

MUKALLA 

AL HUD

AYDAH 

ADEN 

Tihamah 

Sir 

Basin 

Mukalla - Say

Nabitah Suture 

Afif Terrane

(Najran Terrane)

Asir Terrane (An Nimas) 

Nabitah Orogenic Belt (Al Qarah) 

? 

? 

? 

? 

? 

License 

Block 

Thamud-1 

Sanaa 

Basin 

Rayyan 

Basin 

Abyan 

Sab'atayn

(Marib-Shabwah-Hajar) Basin Kharwah-1 

Balhaf

 Basin 

Ash Shuaib-1Hufayr-1 

Khaywan-1 

Alif-1 

Thukmayn-1 

Al Qarn-1 

Balhaf-1 

Balhaf-2 

Al Baydah Islands Arc 1.2-2.5 Ga (older ages from continental basement beneath arc) 

Al Mahfid Gneiss Terrane 1.8-3.0 Ga (Pan-African networking) 

Al-Mukalla Island Arc (?Pan African) 

J. Al Aswad 

High 

Say'un

 -

Beta-1 

Al-Furt-1 

Jiza - 

GULF 

OF 

ADEN 

Howarim-1 

Fartaq 

Rakhawt-1 

A 

B 

C 

Basin 

Boundaries 

al Masilah Basin 

18° 16° 14° 12° 

EXPLANATION 

Location of exploration wells 

Subsurface Najd faults modified from Dyer and Husseini, 1991; 

barbs show relative movement 

Approximate limits of various Precambrian terranes
 

Basin boundary
 

Anticline
 

Volcanic (Tertiary Yemen VolcaJurassic outcrop area (resting oBasement outcrop area (ArcheaCretaceous on basement (JurasPaleozoic outcrop area
 

Province Geology 

Figure 3. Structural elements including basins, highs, faults, and outcrop belts, and cross section locations (red lines) (modified from 

5
 
Yemen (also called Sanaa) became independent of the Ottoman Empire in 1918, and South Yemen became independent of 

a British protectorate in 1967. South Yemen (People’s Democratic Republic of Yemen, PDRY, or Aden) was a Marxistdominated government until it merged with North Yemen to 

form the Republic of Yemen. The unification of the republic 

and the technological revolution in petroleum exploration 

brought into the country in the 1980’s and 1990’s changed the 

country dramatically in both political and economic terms. 

Currently, Yemen has a population of about 17.5 million, most 

of whom are Arabic and of the Muslim faith. 

Political turmoil has surrounded Yemen during its history 

and continues to the present. During the time of separate North 

and South Yemen countries, 1967–1990, hostilities between the 

two countries resulted in the migration of hundreds of thousand of Yemenis from the south to the north. Following unification in 1990, a secessionist effort in southern Yemen in 1994 

failed, and the country remained a republic. It continues to be 

an area in dispute particularly along its northern border with 

Saudi Arabia. 

The complex political history of Yemen contributed to a 

general lack of petroleum exploration until the discovery of Alif 

field in North Yemen in the Ma’Rib–Al Jawf / Shabwah basin in 

1984 (fig. 1) (Beydoun, 1966; Beydoun, 1989; Fairchild, 1992; 

Schlumberger, 1992; Petroconsultants, 1996; Bosence, 1997; 

Maycock, 1997). This successful exploration effort, in provinces 2004 and 2006 (fig. 1), was led by Hunt Oil Company and 

its initial partners from Korea, who formed Yemen Hunt Oil 

Company (YHOC). This company later merged with Exxon 

Yemen to form Yemen Exploration and Producing Company. 

The initial oil discovery at Alif was followed by 11 other discoveries of both oil and gas (figs. 1, 2). 

A second petroleum basin area, here referred to as the 

Masila-Jeza basin (province 2009), lies to the east of the 

Mukalla High (fig. 1). Oil production was established there 

in 1991 by a Canadian Oxy-led consortium (CanadianOXY/ 

CCC/Pecten/Occidental); the discovery of oil at Sunah field 

was rapidly followed by other discoveries at Heijah and 

Camaal and a dozen other fields (Mills, 1992; fig. 1). 

Twenty exploration companies are now active in Yemen, 

mostly independents (International Petroleum Encyclopedia, 

2000). 

Currently, two state-owned oil refineries operate in Aden 

with capacities of 170,000 BOPD and a 10,000 barrel per day 

topping plant in Marib. Two other refineries are in the planning stage including increased capacity (75,000 BOPD) at 

Aden and a 120,000–200,000 BOPD refinery at Mukalla. A 

liquefied natural gas plant, to be built by Enron at Ras Omran 

on the Arabian Sea, is designed to market gas to Asia from the 

gas fields in the Ma’Rib-Al Jawf / Shabwah area of western 

Yemen. A 400-km gas pipeline is planned for construction by 

Enron from the western Yemen gas fields to Ras Omran. The 

implementation of this 1993 plan to market LNG (liquid natural gas) has yet to be completed. As of 2000, oil reserves were 

believed to be 4 BBO and gas reserves are given as 16.9 TCF 

(trillion cubic feet) (International Petroleum Encyclopedia, 

2000). 

Geologic Setting 

Petroleum occurs in two rift basins in Yemen. In western 

Yemen, petroleum is generated and produced in the Ma’Rib–Al 

Jawf / Shabwah basin, and in eastern Yemen in the Masila-Jeza 

basin. These eastern and western basins are largely separated 

by a structural high known as the Mukalla or Jahi-Mukalla High 

(figs. 1, 3). The western basin is known by a variety of names 

such as Sabatayn, Marib-Shabwa-Hajar (Beydoun and others, 

1998), and Marib-Shabwa basin (Brannin and others, 1999; 

Csato and others, 2001). Similarly, the eastern basin is also 

known as the Sayun al Masilah and Jiza-Qamar basin (Beydoun 

and others, 1998), Sayun basin, and Sir-Sayun basin (Csato and 

others, 2001). These basins are part of a system of major rift 

basins, and various authors have used a variety of names for 

both the main basins and the sub-basins or grabens that occur 

within them. The names used herein attempt to represent the 

major petroleum basins or sub-basins within the three provinces 

included in the Madbi Amran / Qishn Total Petroleum System. 

Although the petroleum-bearing grabens are considered to 

be of Late Jurassic age, their origins can be traced back to Precambrian fault systems. During Precambrian time, the area 

underwent a major collision and terrane accretion from about 

955 to 615 million years ago (Ma), when older magmatic 

assemblages (≈2.95–2.55 billion years old) accreted with 

younger magmatic, volcanic, and plutonic rocks (Husseini, 

1989; Whitehouse and others, 1998). However, during the 

Infra-Cambrian (≈615 to 580 Ma), the southern Arabian peninsula became extensional with intrusions of alkali-rich granites 

and volcanics as well as development of salt-filled extensional 

basins. These rift basins were related to major wrench-fault systems such as the Najd, in the western Arabian Shield, which 

consists of a series of northwest-southeast-trending left-lateral 

fault zones as much as 1,100 km long and 300 km wide (Husseini and Husseini, 1990; Ellis and others, 1996). The presence 

of 400 m of Infra-Cambrian syn-rift sediments and metasediments in Yemen (Beydoun, 1997) and the known hydrocarbon 

occurrence related to Infra-Cambrian salt basins in nearby 

Oman (Husseini and Husseini, 1990; Pollastro, 1999) led to 

early exploration efforts that focused on the potential of an 

Infra-Cambrian petroleum system. 

Exploration in the 1980’s, however, demonstrated that the 

Infra-Cambrian sediments were not petroleum bearing, but that 

petroleum potential existed in rocks, rifts, and structures of Late 

Jurassic age. The orientation of the Jurassic rifts is likely inherited from the Infra-Cambrian Najd wrench faults, which were 

reactivated during the Jurassic breakup of the Gondwana supercontinent. The petroleum-bearing grabens of Yemen are interpreted to be the result of a failed arm of a triple junction that 

occurred in Late Jurassic time (Kimmeridgian) (Greenwood and 

others, 1980; Husseini, 1989; Jungwirth and As-Sururi, 1990; 

Schlumberger, 1992; Redfern and Jones, 1995, Csato and others, 2001). Kimmeridgian source rocks and Jurassic-age petroleum systems are important worldwide, particularly within 

extensional basins such as the North Sea (Ahlbrandt and others, 

2000). 

6 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 
Following Jurassic rifting, sediments filled the resulting 

grabens from earliest Cretaceous (Berriasian) through Late Cretaceous time. A second phase of rifting and associated 

transpressional and transtensional structures were related to the 

opening of the Red Sea and the Gulf of Aden during Oligocene 

and Miocene time (Beydoun, 1989; Haitham and Nanai, 1990; 

Bott and others, 1992; Crossley and others, 1992; Huchon and 

others, 1992). During this rifting, sea-floor spreading separated 

Arabia from Africa and the Arabian plate rotated in a counterclockwise direction. Tertiary petroleum systems of the Red Sea 

are largely within the rift sequence, whereas petroleum potential 

in the Gulf of Aden is thought to be largely in the pre-rift 

sequence. The Gulf of Aden is cut by a series of northeasttrending transform faults that reflect the oblique motion of the 

Arabian plate from the Gulf of Aden; the Red Sea rift and 

related structures formed mostly in response to plate movement 

perpendicular to the ocean spreading center. In Yemen, the 

southern portion of the Shabwah basin (known as the Balhaf 

basin) and much of the Masila-Jeza basin (specifically the 

Hadramawt Arch) are also related to transtensional and 

transpressional forces during the Tertiary rifting event (Bott and 

others, 1992; Richardson and others, 1994; Csato and others, 

2001) (fig. 3). 

Total Petroleum System 

The total petroleum system described in this report, the 

Madbi/Amran/Qishn TPS, is entirely onshore. It is a Jurassicsourced, and Jurassic- and Cretaceous-reservoired petroleum 

system. Undiscovered oil and gas resources in this TPS were 

quantitatively assessed. Two other potential total petroleum systems—the Cretaceous Nayfa (Naifa) petroleum system in eastern Yemen and a possible Tertiary petroleum system in the Gulf 

of Aden—were not assessed but are briefly discussed. 

Petroleum Occurrence 

Petroleum is currently produced in two main areas in 

Yemen; cross sections through the main petroleum-producing 

areas are located in figures 2 and 3, and shown in figures 4 and 

5; structural elements are shown in figure 3. Although the stratigraphic nomenclature is complex, the stratigraphic terminology 

used by Beydoun (1997) and Beydoun and others (1998) is 

applied herein. Stratigraphic terminology and spatial relationships of strata are shown for the Phanerozoic in figure 6, for the 

Paleozoic section in figure 7, the Jurassic section in figure 8, the 

Cretaceous section in figure 9, and the Cenozoic in figure 10. In 

figure 6, the general Phanerozoic stratigraphic framework is 

shown (from west to east) across the Sab’atayn (Ma’Rib–Al 

Jawf and Shabwah basins of this report, fig. 1), the Say’un 

Masila basin, and the Jiza-Qamar basin. The latter basin, which 

is not productive, is included as a sub-basin within the MasilaJeza basin. The two petroleum-producing basins (Sab’atayn and 

Sayun Masila) have a common source rock (the Kimmeridgian 

Madbi Formation; Csato and others, 2001), but the subsequent 

depositional and structural histories of the two basins are different, as are the ages and quality of their reservoirs and seals. 

As shown schematically in figure 11, the combined 

Ma’Rib–Al Jawf and Shabwah basins (fig. 1) contain a petroleum system that formed in the Late Jurassic. The basal petroleum source-rock interval in the syn-rift sequence is the Madbi 

Formation, which charges both clastic and carbonate Jurassic 

reservoirs in the Madbi Formation and Sabatayn Foramation of 

the Amran Group; these formations are overlain by a salt seal of 

the Shabwah Member of the Sabatayn Formation (fig. 8). Reservoirs in the Amran Group range from clastic turbidite 

sequences to strata of alluvial origin that were generally deposited along the margins of the rift or as sediment that filled the 

basin progressively from the northwest to the southeast. Salt 

diapirs create additional structures for traps in the western basin 

(figs. 11, 12); however, the salt seal is absent in the eastern 

Masila-Jeza basin, and hydrocarbons sourced from the Madbi 

migrated vertically into the Cretaceous Qishn Formation, where 

reservoirs are largely contained within a clastic estuarine 

sequence (fig. 13). 

The stratigraphic terminology for the Jurassic rocks of 

Yemen is shown in figure 8 and for the Cretaceous in figure 9. 

The maximum extent of the Madbi Amran/Qishn TPS is mapped 

in figure 1 along with the pod of active source rocks (Ro>0.6 

pct). The two basins in Yemen that contain the TPS, the 

Ma’Rib–Al Jawf / Shabwah basin in the west and the MasilaJeza basin in the east, are separated by the Mukalla (or JahiMukalla) high (figs. 1, 2, 3, and 11), which is a northwest-southeast-oriented horst block that has undergone recurrent movement and may reflect the Infra-Cambrian Najd fault system. The 

structural relations between the two basins and this positive feature, which has been a structural high for most of the Mesozoic 

history of Yemen, are not entirely resolved (Paul, 1990, Putnam 

and others, 1997; Beydoun and others, 1998; Csato and others, 

2001). Csato and others (2001) simplified the structural terminology and discussed two basins separated by the Mukalla high. 

They interpreted the Mukalla high to be a persistent geologic 

feature reactivated in the Tertiary rifting but dividing major geologic regimes; to the west extensional features formed, whereas 

to the east major inversion occurred. These authors believed 

Hadramawt High or Arch (fig. 3) to be an uplift related to tectonic rebound from the opening of the Gulf of Aden. This 

rebound was asymmetric; the southern flank tilted southward, 

resulting in high-angle tilted fault blocks in eastern Yemen (as 

shown in fig. 13). 

Jurassic salt halokinesis created additional structural traps 

for hydrocarbon accumulations in the Ma’Rib–Al Jawf / Shabwah basin. However, Jurassic salt was not deposited in the 

Masila-Jeza basin to the east, where structures are indicative of 

inversion and uplift associated with transtensional and transpressional forces and the more east-west orientation of Tertiary rifting (fig. 11). These Tertiary forces also modified the south end 

of the Ma’Rib–Al Jawf / Shabwah basin creating the Balhaf 

basin (fig. 3), which has no recorded hydrocarbon production 

(Crossley and others, 1992; Beydoun and others, 1998; Csato 

and others, 2001). 

Total Petroleum System 7 
8
 A 

Distance in km 210 120 80 75 70 120 55 

S a b ' a t a y n B a s i n Aswad Balhaf Hajar Jahi- Mukalla Say'un 

High Basin Sector High 

Sanaa Basin 

(platform) (Marib - Shabwah Sector and Central high) w

Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen SEA LEVEL 

TD 3X 15 Y 48 

Al Q

TD 1907 X 15 Y 47 46` 

o 

o 

Thukmayn-1 

Q 

TD 3998 

? 

? 

Hufayr-1 

Qishn 

Nayfa 

Sab'atayn 

Madbi 

(NC) 

? Balhaf-2 

Rus 

UeR 

Tawilah Gp (Undifferentiated) 

Sh 

K 

TD 2842 X 14 Y 47 02` 

o 

o 

Ash Shuaib-1 

Shuqra 

Kuhlan 

TD 2753 X 15 Y 46 50` 

o 

o 

Kharwah-1 

Nayfa 

TD 4184 X 15 33` o 

Alif-1 

Recent/Q Tawilah Gp 

(Undiffer.) 

Madbi 

Shuqra 

Kuhlan 

Kuhlan 

'Akbarah 

Wajid 

Amram Gp. Undiffer. 

Khaywan-1 

TD 1797 X 16 Y 44 01` 

o o 

? 

Sa'ar 

Scale 

40 km 

400 m 

Sab'atayn 

Basin 

? 

? 

Shuqra+Kuhlan 

Qishn

Sab'atayn 

Quaternary Umm er Radhuma Fm. Rus Fm. Jiza Fm. 

EXPLANATION 

UeR 

Q 

R 

J 

49` 

39` 

20` 

16` 

o o 

Sh Shuqra Fm. Y 45 48` X 14 o 44` 

K Kuhlan Fm. X 14 o 18` 

Oil production Gas and condensate Sandstone 

Y 47 o 

37` Dolomite 

(NC) Gas, noncommercial Siltstone Limestone 

X Latitude N. Shale Halite Y Longitude E. 

Exploration well test 

TD 4096 Y 47 57` 

Marl Anhydrite 

Figure 4. Cross section A–B across western and central portions of Yemen from Ma'Rib–Al Jawf/Shabwah basin into Masila-Jeza basin (modifi

total depth (in meters). Correlations queried where uncertain. 
B 

Distance in km 145 75 135 60 160 90 195 

Masila Sector of Say'un - Masila Basin J i z a
 Q a m a r B a s i n 

extending into Tertiary offshore Fartaq (Jiza Sector)
 (Qamar Sector) HadramMukalla-Sayhut Basin High Scale 

Q 

UeR 

SEA L Al-Fatk-1 

EXPLANATION T TD 2750 

D X 16o 02` Lusb Mb Quaternary Y 52o 19` 

Maljan-1 Beta -1 Tarfay

? T 

Maqrat Mb Basement Kuhlan TD 4502 o Lusb Mb Madbi Jiza Fm. Sa'ar 

L 

M 

D 

ukalla 

Ha 

ra 

a 

m

e 

iz

s 

Ta 

s iy 

a 

Sarar T 

Jiza Al-Furt -1 

R 

h 

h 

y 

h 

r R 

a 

u

a 

mm

at 

d 

m 

e 

Q 

R 

M 

U 

is 

k 

y

h 

a 

n 

rta 

Sa 

h 

q 

rs 

S

fa 

Q 

t 

t 

is 

b 

F 

n 

D 

Umm er Radhuma Fm. TD 2850 

Rus Fm. Y 51 47` 

o 

Wadi-Jeza-1 

h 

k 

a 

Kuhlan Fm. 

Y 50 23` 

TD 4404 

X 16o 18` Y 52 37` o 

N

r 

a 

M 

a

is 

M 

r 

F 

U 

J 

u 

a 

a 

R 

H b 

hd

Harsh 

bshiyah 

S 

q 

r a 

a 

a 

u 

a 

rta 

m 

a 

q 

h 

m 

F 

a 

h 

a 

y 

a 

u 

a 

q 

r

n 

a 

F 

iy s 

n 

Q

rta 

u 

r

a 

Mad 

i 

b 

b 

i 

d 

r 

a 

a 

ishn

ar 

a 

rta 

h 

Shuqra Fm. X 14 o 51` TD 4300 o 

LEVEL Sufla Mb Sarar-1 Masilah-1 M 

Q 

M 

yfa 

is

q 

M 

ta

t 

Sa'a 

yfa 

lla 

kalla 

h 

h 

a 

N 

u 

H

Q 

Ma 

UeR 

X 17TD 1Y 51 

TD 2485 X 15 24` Y 49 13` 

o o 

i 

n 

H b 

a

Sa'a 

F 

Ghaydah 

H

J

Mukall 

Harashiyat 

H 

a 

u 

lla 

rw 

N 

q 

UeR

Fartaq 

Q

' 

iy

a 

Rus ? D ? 

40 km 

400 m 

Duha Suhis Mb (projected) Y 50 19` Habshiyah Fm. Sa'af Mb X 16o 15` Tuhayr Mb at 3500 X 16 o 23` 

Sh /K 

Sufla Mb 

TD 3443 Shuqra ? Infra -Cambrian 

H. Hab
 

R
 

J
 L
 

S 

M 

T 

D 

Sh 

K 

J/Jurassic/Triassic
 Basement Basement estimated at depth of at least 6500 below s

P/C Permian/Carboniferous
 at 4420 (projected) o X 15 01` 
 Qus Qusaiba (Silurian)
 Y 51o 02` Sandstone Dolomite 

/O Cambro - Ordovician
 

 Paleozoic
 Siltstone Limestone X Latitude N.
 Shale Anhydrite	 Y Longitude E.
 

Marl 

Volcanics 

Exploration well test
 

Figure 5. Cross section B–C across central and eastern Yemen principally in Masila-Jeza basin (modified from Beydoun and others, 1998). TD, total dwhere uncertain. 

Total Petroleum System 9
 
10 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 

N20° 

Ghabar Group Occurs in small faulted grabens in coastal areas centered on 14°30' N. 

48°45' E. 

Era Period, Epoch, Age System, Series, Stage W 42°E 45°E 48°E 

Red Sea HIgh Plateau (Platform) Sab'atayn Say'un Masila Bas

Pliocene 

Messin./Tort. Serrav./Langian Burd./Aquit. Chattian Rupelian Priobonian Barton./Lutetian Ypresian Thanetian Mont./Danian 

Maastrichtian Campanian Santonian Coniacian Turonian Cenomanian Albian Aptian Barremian Hauterivian Valanginian Berriasian Tithonian Kimmeridgian Oxfordian 

Callovian Bath./Baj./Aalen Toarc./Hettang 

TRIASSIC PERMIAN CARBONIFEROUS DEVONIAN SILURIAN ORDOVICIAN CAMBRIAN INFRA - CAMBRIAN 

PALEOZOIC 

JURASSIC 

MESOZOIC 

CRETACEOUS 

CENOZOIC 

PALEOGENE NEOGENE 

Paleoc. Eoc. Oli. Mioc. U/Late U/Late L/Early L/E Middle M 

L L L U U U M M 

o o oo

o 

o 

o 

o 

o o o 

oo o 

o o 

oo o 

o 

o 

o 

o 

o o o 

o 

o o

o 

o o

o o 

o o 

o o 

o o 

o o 

o 

o o o 

o 

o o

o o o o

o o o

o o

o oo 

o o o

o o o o o o o 

o 

o 

oo 

o o o o o o o 

o o o

o 

o o 

o 

o o o 

o 

o o 

o oo 

oo o o o 

o o o 

o o o o 

o oo 

o o o

^^ ^ ^ 

^ 

^ 

^ ^ ^ ^ ^ 

^ ^ ^^ ^ 

^ ^ 

^ 

^ ^ ^ ^ ^^ ^ ^ ^ 

^ ^ ^ 

^ 

^ 

^ 

^ 

^ ^ 

^ ^ ^ ^

^ ^ ^ 

x x

? 

? 

? 

? ? ? 

? 

? ? 

INSET: Pre Jurassic 

(South flank, 

Overlain by th

Ye

men 

Volcanic 

Group 

Tihamah 

Group 

Wajid 

Madbi 

Shuqra Shuqra 

Kuhlan 

Kuhlan 

Madbi 

Sab'atayn 

Amran Group 

Undifferentiated 

Nayfa 

Tawilah Group 

Undifferentiated 

Tawilah Group 

Majzir 

Mayfa'ah 

Hadramawt 

Group 

Coastal and offshore area Gulf of Aden Sh

Rus 

Kaninah 

Umm 

Sa'ar 

Nayfa 

Sa'ar 

Akbarah 

Mu

Q

Harshiya

No Jurassic or Nayfa - Sa'ar 

Cretaceous Qishn 

On Basement 

Juwayl 

Khusayyayn 

Qalibah 

Dibsiyah 

Qinab Group 

Sudair 

Amran Gp 

JahiMukalla High 

Basin 

L U 

EXPLANATION 

Sandstone Marl Halite o o o Conglomerates Other igneous
 Siltstone Limestone Volcanics Coal ^^^ Chert
 Shale Anhydrite Shale stringers x x x Intrusive granite Fanglomerates, breccias, turbid

Figure 6. Phanerozoic lithostratigraphy, correlations, and spatial stratigraphic distributions for Yemen (modified from Beydo

formation status only. Correlation or extent queried where uncertain. 
STEPHANIAN 

WESTPHALIAN NAMURIAN VISEAN TOURNAISIAN FAMENNIANFRASNIAN GIVETIANEIFELIAN EMSIANGEDINNIAN PRIDOLILUDLOW WENLOCK LLANDOVERY ASHGIL CARADOC LLANDEIL LLANVIRN ARENIG TREMADOC MERIONETH ST. DAVID'S CAERFAI 

INFRA-CAMBRIAN 

Mb 

o o 

o 

o 

o o o

o 

oo o o o ooo o 

o o o o o o o o o o o o o o

o 

o 

o 

o 

o 

o o 

o o o o

o o

o 

o 

o o

o o o 

o 

o o

o o o

o 

o o o

o o 

o o 

o o 

o o o o oo o 

o o o o o 

o o o oo 

o o o o 

o 

o o 

o 

o o o

o 

o o

o 

oo 

o o 

o 

o 

o 

o o o 

o 

o o o

o o o o

o oo o o 

? 

? 

? 

? 

? 

? ? 

? 

? 

? ? 

? ? 

? 

? 

? 

? 

? 

? 

? 

? 

? 

? 

? 

? 

"J'BALA

Siq/Ya

Saq 

Dibsiyah Mb Fm Dibsiyah 

QINAB Group 

Qa

F

Zarqa/Sarah Sanamah 

Qusaiba Q

Qalibah 

Wajid 

Ur Khusayyayn 

Mb 

Ur Khusayyayn 

Mb 

Khusayyayn 

Khusayyayn 

Fm 

Fm 

Juwayl 

Juwayl Mb 

Khuff Fm 

Sudair 

SAUDI ARABIA 

Subsurface (1

Najran outcrops 

Sudair 

Juwa

yl Fm 

W SW 

Rub' Al Khali - Centr

Al 

Jawf 

YEMEN 

Subsurface 

Rub' Al Khali Basin South Flank 

'Akbarah 

Fm 

Outcrops 

NW Yemen 

Qusaiba 

Wajid 

Fm 

(Undifferentiated) 

GHABAR 

GP Coastal area 

west of Mukalla 

L U L M U L M U L L L M U U 

DEVONIAN CARBONIFEROUS SILURIAN PERMIAN ORDOVICIAN CAMBRIAN

TRIASSIC 

Period, Epoch, Age 

System, Series, Stage 

o 

Fm 

Mb 

F

Fm 

Fm 

Fm Fm

E 

Mb 

M M U 

Total Petroleum System 

Figure 7. Paleozoic lithostratigraphy, correlations, and spatial stratigraphic distributions for Yemen and adjacent Saudi Arabia (modified from Beextent queried where uncertain. 

11
 
12
 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen o o o o HIGH (E) PLATEAU OUTCROPS TAWILAH Gp 

W (W) (NW) (SE) (W) 

SERIES 

EPOCH STAGE AGE 

BERRIASIAN 

(CRETACEOUS) 

Upper/Late 

MALM 

KIMMERIDGIAN TITHONIAN 

Lower/Early 

AALENIAN TOARCIAN 

PLIENSBACHIAN 

SINEMURIAN HETTANGIAN 

TRIASSIC 

LIAS 

Middle 

DOGGER 

CALLOVIAN BATHONIAN BAJOCIAN OXFORDIAN 

SAB'ATAYN BASIN 

(MARIB-SHABWAH-HAJAR) 

AND BORDERING OUTCROPS 

NAYFA m 

Safir Mbs 

Ayad 

Mb 

Maqah Mb 

Layadim 

Mb 

Shabwa Alif Mb Seen Mb 

Yah Mb 

Lam 

Mb 

A M R A N 

A M R A N MADBI Fm MADBI Fm Meem 

MADBI 

Ur. Madbi Shales 

Mb 

Maabir 

Mb 

Maabir 

Mb 

Lr. Madbi Shales 

Mb 

A M R A N Rafad Mb 

SABA'TAYN 

Tr

Fm

ansition 

Haniyah Mb 

SHUQRA 

Fm 

SHUQR

Fm 

Arwa 

Mb 

Hanb

Mb 

Nayfa 

Breccia 

Mb 

Raydan

Mb 

KUHLAN 

Fm 

K

? 

JAHIMUKALLA 

HIGH 

C T 

A C 

SAY'UN-MAS

Rafad 

? 

? 

? 

NO JURASSIC: CRETACEOUS RESTS ON BASEMENT 

o 

o 

o o 

o o 

o o o o o

oo 

o o o

oo o o o 

o 

o o o

o o o o o o

o o 

o 

o o

o o

o o

o 

o 

o 

o 

o 

NAYFA 

o o

F 

Mbs 

G R O U P 

G R O U P 

Mb 

G R O U P 

R 

E E 

O

U

S

Mb 

EXPLANATION 

Sandstone Limestone o o o Conglomerates Siltstone Anhydrite Fanglomerates, breccias, turbidites. Shale Halite Occur along some rifted basin mMarl 

Volcanics 

Figure 8. Jurassic lithostratigraphy, correlations, and spatial stratigraphic distributions for Yemen (modified from Beydoun and ot
? 

? 

SERIES 

EPOCH STAGE AGE 

EOCENE 

PALEOCENE 

MAASTRICHTIAN CAMPANIAN SANTONIAN CONIACIAN 

TURONIAN 

SENONIAN 

UPPER/LATE 

CENOMANIAN ALBIAN 

"MIDDLE" 

APTIAN BERREMIAN 

HAUTERIVIAN 

LOWER/EARL VALANGINIAN Y 

NEOCOMIAN 

BERRIASIAN 

JURASSIC (Tithonian) 

44°E 7°E 0°E 

? 

? ? 

? 

? 

? 

? 

? ? ? 

? 

? 

? 

o oo o 

o 

o 

o 

o 

o 

o 

o 

o o o o o 

oo 

o 

o 

o 

o 

o o o 

o 

o o o o o o 

o 

o 

o o o 

o 

o o o o o 

o 

o 

o 

o 

o 

o o 

o 

o 

o o 

o o o 

o 

Clastics 

SA'AR 

Fm JAHI-MUKALLA 

High 

no Sa'ar, Nayfa 

or 

Jurassic Fm 

NAYFA 

UMM er RADHUMA Fm 

SHAR

WAYN Fm 

DAB

MUKALLA Fm 

Lusb Member 

Maqrat Mb 

Tuhayr Mb 

WEST 

Majzir 

Fm 

Duha Suhis 

Member FA

R

TAQ 

QISHN 

Fm 

Sa'af 

Mb 

Qishn 

QISHN 

HARSHIYAT 

Fm 

Rays Mb 

NAYFA Fm 

Samarma 

SA'AR Qala

Al 

Sufla Mb 

T A W I L A H G R O U P 

(Undifferentiated) 

QISHN Fm 

4 5 

o 

Mb 

Fm 

F

Carbonate Mb

Mb 

Fm 

Gh

Total Petroleum System Figure 9. Cretaceous lithostratigraphy, correlations, and spatial stratigraphic distributions for Yemen (modified from Beydoun and others, 1998). 13
 
14 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 

TIHAMAH GROUP 

Barqan 

Gp 

System/ 

Series/Stage 

SAUDI ARABIA 

PLEISTOCENE 

NEOGENE 

MIOCENE OLIGOCENE 

PALEOGENE 

EOCENE PALEOCENE PLIOCENE Piacenzian Zanclian Messinian Tortonian Serravalina Langhian Burdigalian Aquitanian Chattian Rupelian Priabonian Bartonian Lutetian Ypresian Thanetian Danian 

Y E M E N 

E W Gulf Aden Gulf 

OMAN (

? 

? 

? 

? 

? ? ?? ? 

? 

? 

? 

? 

? 

? ? 

o 

o o o

o o 

o 

o o 

o 

o o 

o 

o o

o 

o o 

o 

o 

o o 

o 

o 

o 

o 

o 

o o 

o o

o 

o 

o 

o o 

o 

o o o

o 

o 

o 

o o o 

o 

o 

o o o o 

o 

o o o 

o oo o 

o 

o o o o o 

o 

o 

o 

o 

o 

o o

oo 

o 

o 

o 

o o 

o 

o o

oo o 

o 

o 

o 

o 

o o o

o o o 

o 

o 

o o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o o

oo o 

o 

o 

o 

o o o

o o

o o 

o o 

o o o

o o o o 

o 

o 

x 

N S 

Shammar Mb 

TAWILAH GP 

(Undiff.) Sharwayn Sharw

F

CRETACEOUS (Maastrichtian) 

L L M L U U U U 

S W 

R

Conglo

Irqah 

Formation 

Subsurface/Exposures 

Sarar 

Formation 

Lisan 

Fm 

Ghawwas Fm Ghawwas Mb Mansiyah Fm 

Kial Fm 

J. Kibrit Fm 

Barqan Fm 

Al Wajh Fm 

Abbas Fm 

Kamaran Mb 

Subsurface Exposure 

Y E M E N C A N I C Not penetrated Zaydiyah Fm 

Maqna Fm 

Salif Fm 

Onshore Exposure Offshore Subsurface 

Jizan 

Volcanics 

Fuwwah Fm Hami 

Fm 

S H I H R 

Taqah Fm 

Ghaydah 

Fm 

Libakhah Fm 

Ambakhah Fm 

Buwaysh Fm 

Rus Fm 

Jiza 

Umm er Radhuma 

Jawl Mb 

Transition 

HADRAMAWTGP 

Mayfa'ah 

Fm Kaninah Fm 

Habshiyah 

Fm 

Ain Ba Ma'bad Mb 

Ash

Fm 

Zulum

Aydim 

Da

F

Rus 

Um

Rad

F

Mug

F

Adaw

Majzir 

Fm 

Lahimah 

Mb 

Bald Bathan Fm 

of E o

o 

o 

o 

L M L U 

Red Sea Red Sea

V O L G R O U P 

G P 

Fm 

Beds 

Figure 10. Cenozoic lithostratigraphy, correlations, and spatial stratigraphic distributions for Yemen, Oman, and Saudi Arabia (modified from Bey

uncertain. 
The Ma’Rib–Al Jawf / Shabwah basin in western Yemen 

was initiated during the Jurassic and was related to rifting of the 

Arabian plate from the Gondwana supercontinent. Pre-rift sedi� 

mentation is represented by mostly continental deposits of the 

Kuhlan Formation (fig. 8); this formation includes fluviatile and 

arkosic redbeds that grade upward into a shallow-marine facies 

and represent the early transgressive phases of the Late Jurassic 

seas. It is essentially absent of fossils; however, in the subsur� 

face some palynomorphs have been recovered indicating a Mid� 

dle Jurassic (Bathonian to Early Callovian) age (Beydoun and 

others, 1998). These continental rocks are overlain by shallowmarine fossiliferous carbonates such as the Shuqra Formation of 

the Amran Group (fig. 8). 

During the Late Jurassic, commencing in the Kimmerid� 

gian and continuing through the Tithonian, syn-rift sediments of 

the Madbi Formation were deposited (Beydoun and others, 

1998). The Meem Member of that formation (fig. 8) consists of 

clastic turbidites and shales that are important source rock as 

well as reservoirs in the western basin. The middle Maabir 

Member is largely a carbonate sequence and a petroleum reser� 

voir, and the upper Lam Member is mostly shaly strata. Clastic 

reservoirs also occur in the Madbi Formation and reflect deepmarine sand deposition along the flanks of grabens or half-gra� 

bens. Simultaneously continental sediments filled the grabens 

from the north end of the western basin along rift margins. In 

particular, these sediments formed the Safer, Alif, and Yan 

Members of the Amran Group (fig. 8). Apparently, ocean circu� 

lation in the western Yemen basin became restricted during the 

Late Jurassic, and salts of the Shabwah Member of the Sabatayn 

Formation were deposited over the syn-rift sequence, thereby 

providing a seal for the Jurassic petroleum system. 

The tectonic history of the Masila-Jeza basin was somewhat different from that of the Ma’Rib–Al Jawf / Shabwah 

basin. Whereas the basal source rocks of the Madbi Formation 

were deposited in a syn-rift setting, the overlying sequence was 

relatively starved for clastic sediment input. A much later Creta� 

ceous transgression of the Qishn Formation was thus required to 

provide both reservoir and sealing carbonates, as illustrated in 

figures 11 and 13. In eastern Yemen, ocean circulation remained 

open during the Late Jurassic and Early Cretaceous, and open 

marine carbonates and clastics were deposited—but with no 

Upper Jurassic salt seal (figs. 11, 13). Further, the eastern 

Yemen basin reflects east-west-oriented Tertiary rift forces, 

compared to the western Yemen basin, which was dominantly 

influenced by northwest-southeast-directed Jurassic-age forces, 

inherited from Infra-Cambrian faulting (fig. 13). 

The preferred pre-rift, syn-rift and post-rift sedimentary 

sequences, as designated in this report, are consistent with those 

shown by Csato and others (2001) (figs. 12, 13). Brannin and 

others (1999) considered only the Madbi Formation and what 

they referred to as the Lam Formation to be syn-rift deposits. 

(Note that Beydoun and others, 1998, considered the Lam to be 

a member of the Madbi Formation.) Stratigraphic divisions and 

correlations advanced by Beydoun and others (1998) made a 

significant contribution toward clarifying the stratigraphic corre� 

lations in Yemen (figs. 6–10). The pre-rift Shuqra Formation, as 

defined by Beydoun and others (1998), is a neritic limestone 

with richly fossiliferous marls and does not contain potential 

source beds. Interestingly, the Shuqra contains crocodile 

skeletons estimated to be as much as 3 m long. The Shuqra 

source beds as referred to by Brannin and others (1999) are 

likely the Lower Madbi Shale Member of Beydoun and others 

(1998). 

The pre-rift sequences are similar in both the eastern and 

western Yemen basins, but the syn-rift fill in the east has consid� 

erably less sandstone (potential reservoirs). Structures in the 

eastern basin are mostly related to rejuvenation of basin zones of 

weakness in response to both Jurassic and Tertiary rifting forces, 

rather than related to salt diapirism, as is evident in the western 

basin. Both basins have multiple grabens and half-grabens that 

form stratigraphic traps, particularly along the margins of adja� 

cent horsts. 

Only oil fields are found in eastern Yemen, reflecting a 

lower thermal maturation of the Madbi shales relative to those in 

the western basin. Thus, vertical migration of Madbi-sourced 

hydrocarbons charge mostly Jurassic reservoirs beneath the salt 

seal in the west. In the eastern basin where no salt is present, the 

hydrocarbons migrate upward, are trapped in the Qishn Forma� 

tion’s fluviatile, estuarine, and tidal sandstone reservoirs, and are 

sealed by impermeable Qishn carbonates and shales (figs. 11 

and 13). The Qishn deposits represent a transgressive marine 

sequence progressing from east to west across Yemen that 

grades laterally westward into clastics of the non-petroleumbearing Tawilah Group (fig. 9). 

Source Rock and Oil 

Within Yemen, geochemical data from 12 oils are reported 

in the GeoMark (1998) oil database. Seven oils are from Juras� 

sic reservoirs in the Ma’Rib–Al Jawf / Shabwah basin; of these, 

six samples are from Alif, Azal, and Shabwah fields, and one 

sample is from an oil seep. Three oils are from Jurassic and 

Cretaceous reservoirs in the Masila-Jeza basin (Sunah, Hemiar, 

and Camaal fields; fig. 1), and two other samples are from Ter� 

tiary reservoirs in the Gulf of Aden. Although three groupings 

of oil were identified, oils from Jurassic reservoirs are dominant 

in both basins. The nine Jurassic-reservoired oils (seven from 

the west, two from the east) are genetically similar. API gravi� 

ties range from 29° to 35°, sulfur content from 0.09 to 0.59 percent, and pristine / phytane ratios from 1.46 to 1.72. Biodegra� 

dation is suspected in the seep sample from the western basin 

due to its low API gravity of 14°, high sulfur content of 6.3 percent, and low pristine / phytane ratio of 0.3. The Cretaceous oil 

sample from Hemiar field in the eastern basin is distinct from all 

other oil samples, perhaps due to biodegradation; its gravity is 

lower (22.2°), and sulfur content is higher (1.23 percent), but its 

pristine / phytane ratio of 1.69 is within the range of the Jurassic 

samples. The Gulf of Aden Tertiary oils are also different, in 

that they have high pristine / phytane ratios, 2.02 to 2.92, and 

reduced δC13values (<–24) as compared to all other samples 

whose δC13values range from –26 to –28.3. Some oil from the 

Gulf of Aden is anomalously high gravity, as much as 43°, as 

noted by Beydoun (1989). These data indicate that the onshore 

oils in Mesozoic rocks dominantly belong to one genetic oil 

family, although biodegradation is suspected in the seep and 

Hemiar samples. The offshore, Gulf of Aden oils reservoired in 

Cenozoic rocks are from a different oil family. 

Total Petroleum System 15 
16
 MA'RIB-AL JAWF/SHABWAH MUKALLA HIGH MASILA-JEZA 

NW (SAB'ATAYN) BASIN (SAY'UN) BASIN 

Jurassic sandstone progradation 

Heavy oil 

Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen Maabir Mbr. Maabir Mbr. 

Rafad Member 

Turbidite 

reser

voirs 

Nayfa Fm. 

Nayfa-Sa

Madbi Fm. 

Jur. A

mran 

reser

v

oirs 

(Safer, Alif 

Yan 

Members) 

Shuqr

a Fm. 

Tawilah Group 

Meem Member 

Lam Member 

Haniyah Member 

CRETACEOUS 

Fractured loses sealing capacity Saba'tayn Fm. 

(Shabw

a Mbr.) 

ift ost-r P

fill 

Pre-rift Rift 

sag 

Alif, Meem, Amal, Raydan, and other fields 

Hemiar, HQamaal, a

EXPLANATION 

Sandstone
 Carbonates Evaporites
 

Siltstone and shale	 Turbidites 

Volcanics Petroleum mig

Oil reservoir 

Figure 11. Schematic diagram of total petroleum systems in Ma’Rib–Al Jawf / Shabwah and Masila-Jeza basins, Yemen. 
SW Tertiary NE 

0.5 

1.0 

1.5 

2.0 

0 5 km 

Rejuvenation of Jurassic 

Faults 

Rifting 

Reactive to Active Diapirism 

U. Cretaceous 

Tawilah Fm. Passive Diapir Growths 

1 1 

2 

2 Madbi Hydrocarbon System 

Naifa Hydrocarbon System 

TWT (sec) 

L. Cretaceous (Aptian-Albian) 

Qishn Fm. 

L. Cretaceous (Valang.-Hauteri.) 

Naifa Fm. 

Post-Rift 

Naifa Fm. 

U. Jurassic (Kimmer.) 

Madbi Fm., Meem Mbr. 

U. Jurassic (Kimmer.-Tithonian) 

Madbi Fm., Lam Member. 

Tithonian Rifting 

Basinal and Marginal 

Clastic Deposition 

Salt 

Earliest L. Cretaceous (Berriaz.) Uplift of Northern Edge

Reactive/Passive Initiation of 

Diapirs 

M. Jurassic Pre-Rift 

Marine Carb. 

Fluvial 

(Kohlan-Shuqra) 

Figure 12. Tectono-stratigraphic, halokinetic, and petroleum generation history model of Ma’Rib–Al Jawf / Shabwah basin, 

western Yemen (with permission from Csato and others, 2001). TWT, two way time. 

The source of hydrocarbons from the Madbi Amran / Qishn (Naifa) source rocks (Csato and others, 2001; fig. 14). Csato 

TPS is believed to be Upper Jurassic Madbi (Kimmeridgian age) and others (2001) reported thermally mature Madbi Formation 

shales (figs. 14, 15). Petroleum-migration modeling in the in the Lam and Maabir-Meem members to contain source rocks 

deeper western basin demonstrates the effectiveness of Madbi with total organic carbon (TOC) ranging from 1.4 to 3.6 weight 

source rocks and the thermal immaturity of Tithonian Nayfa percent, hydrogen indices (HI) of 180–370 and TMAX values 

Total Petroleum System 17
 
N S 

Gulf of Aden 

Somalia 

Somalia 

South Arabian Peninsula 

South Arabian Peninsula 

? 

Coastal Strip 

uplift 

inversion transtension tilting ocean floor 

Cretaceous 

Paleogene 

1 

Naifa Fm. 2 

Madbi Fm. Madbi Hydrocarbon System 

Naifa Hydrocarbon System 

Qishn Fm. 

Half-Graben 1 

S.Hadramaut High 

S.Hadramaut Complex 

oceanic crust 

1 2 

S.Hadramaut Complex ? 

U. Jurassic 

M. Jurassic 

Figure 13. Tectono-stratigraphic and petroleum generation model of Masila-Jeza basin, eastern Yemen (with permission from Csato and others, 2001). 

ranging from 224°C to 229 ̊C. Brannin and others (1999) 

reported TOC values of 2–5 percent and HI’s of 580 for the 

Madbi Formation in the western Yemen basins, and reported as 

much as 12 percent TOC (Rock Eval) in the pre-rift Shuqra Formation with HI greater than 300. Thermal maturation of Madbi 

source rocks is believed to commence with oil generation at 

about 2,700 m (Csato and others, 2001). Thermal maturation 

modeling shows that with high heat flow, Madbi source rocks 

may have expelled oil from 135 to 90 Ma, and with low heat 

flow, from 85 to 50 Ma (Csato and others, 2001). Both models 

apply inasmuch as a variety of structural configurations and variable heat flow exist within and among the basins. Essentially, oil 

generation commenced in the Late Cretaceous following deposition of significant post-rift clastics of the Tawilah Group (figs. 9, 

12, 13). 

In summary, the Kimmeridgian shales of the Madbi Formation are probably the principal source rocks in both the eastern and western onshore basins of Yemen. One total petroleum 

system was identified and assessed for both basins (fig. 1). 

Reservoir Rock 

Reservoirs in the two basins are dependent primarily on the 

presence or absence of the Upper Jurassic (Tithonian) salt of the 

Sabatayn Formation (Shabwah Member) (fig. 8). In the western 

Ma’Rib–Al Jawf / Shabwah basin, reservoirs beneath the salt 

consist dominantly of clastics deposited either along the 

margins of the various grabens (Hayniyat and Rafad Members, 

fig. 8) or as turbidites (Meem and Lam Members) in the deeper 

18 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 
Figure 14. Thermal maturation modeling (PetroMod 4.2) for Ma’Rib–Al Jawf/Shabwah basin, western Yemen (with permission from Csato and 

others, 2001). Profile location shown in figure 1. Hydrocarbon generation commences at R0 = 0.7 percent vitrinite reflectance (green color) or 

higher. 

portions of the grabens (figs. 8, 11). The upper part of the Jurassic Amran Group and its coarser clastic units, Alif, Seen, Yah, 

and Safir Members of the Sabatayn Formation, are the principal 

reservoirs in the western basin (fig. 8). 

The Madbi Amran / Qishn Total Petroleum System takes its 

name from the Madbi Formation source rocks and the Amran 

Formation (Jurassic Tithonian) carbonate and clastic reservoirs 

in the western basin beneath the salt and the Qishn Formation 

(Cretaceous Berriasian) clastic reservoirs in the eastern basin 

where no salt is present (figs. 11, 13). Reservoirs in the western 

basin are relatively shallow, with depths ranging from 1,829 to 

2,286 m (from 6,000 to 7,500 ft) in the west (Petroconsultants, 

1996). Initially, much of the production was established in 

Jurassic carbonate intervals; however, production from sandstones became more dominant as the fields were more fully 

developed. Porosities for the sandstones generally range from 

15 to 28 percent, with permeabilities ranging from 80 millidarcies (mD) to 4 darcies. Most Jurassic sandstones have permeabilities in the several hundred millidarcy range, and commonly 

in the one-half darcy range (Petroconsultants, 1996). Some reservoirs have lower porosities resulting from halite cement 

present in the pores, and some production problems are related 

to salt precipitation and salt production in the western basin reservoirs (Schlumberger, 1992). 

Reservoirs in the western basin were charged by vertically 

migrating hydrocarbons that were trapped beneath a salt seal 

formed by the Shabwah Member of the Sabatayn Formation (fig. 

8). Halokinesis in the western basin commenced in Early Cretaceous time and strongly influenced reservoir distribution there 

(fig. 12). Thickness of these formations and members changes 

abruptly, depending upon their position relative to the horsts and 

grabens in the basins and their relations to salt dynamics (thin 

over diapirs, thick in salt removal areas). The Jurassic syn-rift 

fill is as much as 4 km thick in the western basin, and individual 

coarse clastic intervals along some rift margins are as much as 

900 m thick (Brannin and others, 1999). Thus, some individual 

reservoirs may be several hundred meters thick, but thin 

abruptly across intervening horsts (figs. 4, 5, 12, 13). Turbidite 

reservoirs and basin margin clastics are also important syn-rift 

reservoirs that intercept and trap hydrocarbons generated from 

the deep marine source rocks of both the Meem and Lam Members of the Madbi Formation. Fractured rocks of the Maabir 

Member also have produced hydrocarbons, as have the pre-rift 

successions of the Shuqra (carbonate) and Kuhlan (clastic) Formations. Reservoirs in these latter two formations are secondary 

and generally of poorer quality relative to the Upper Jurassic 

reservoirs (Brannin and others, 1999). 

In the Masila-Jeza basin, the Upper Jurassic salt is absent 

and the principal reservoir and trapping conditions exist in the 

transgressive Qishn Formation (fig. 9), which may be as much as 

several hundred meters thick. The principal reservoirs occur 

within a 75-m clastic interval of mixed sands and shales underlying a carbonate facies (Putnam and others, 1997) (fig. 11) that 

forms a seal for Madbi Formation hydrocarbons migrating vertically as shown in figure 11. The eastern basin reservoirs are 

shallower than those in the western basin with producing depths 

of about 1,524 m at Camaal, Heijar, Heimar, Haru, Suna, and 

Tawila fields (Petroconsultants, 1996; Putnam and others, 1997; 

fig. 1). Reservoir quality for Qishn clastics is excellent. At 

Camaal field, all Qishn reservoirs exceed 23 percent porosity 

with permeabilities exceeding 1 darcy (Putnam and others, 

1997). Petroconsultants (1996) also reported high porosity and 

Total Petroleum System 19 

0 (meters) 3000 6000 

0 

1000 

2000 

3000 

5000 m 

Mintaq-1 

Tawilah 

NaifaQishn 

Madbi 

Kohlan 

SW NE

Vitrinite 

Reflectance 

Percent 

0.200–0.300 

0.300–0.400 

0.400–0.500 

0.500–0.600 

0.600–0.700 

0.700–0.800 

0.800–0.900 

0.900–1.000 

1.000–1.100 

1.100–1.200 

1.200–1.300 

1.300–1.400 

1.400–1.500 

1.500–1.600 

1.600–1.700 
20
 

PRE-RIFT 

SYN-RIFT 

POST-RIFT 

Gulf of Aden 

0 

600 

500 

400 

300 

200 

100 

50 

550 

450 

350 

250 

150 

P

Ju

Cretaceous 

aleogene 

rassic 

Triassic 

Permian 

570 

510 

439 

408 

363 

248 

206 

144 

65 

Precambrian 

Cambrian 

Ordovician 

Silurian 

Devonian 

323 

290 

E 

M 

L 

E 

E 

E 

E 

E 

M 

M 

E 

E 

E 

E 

M 

M 

L 

L 

L 

L 

L 

L 

L 

M 

L 

L 

Mississippian 

Pennsylvanian 

Neogene 

24 

Pal 

Eoc 

Olig 

Mio Plio 

KH 

QB 

GH 

AM 

QN 

TW 

MK 

UR 

R 

HB

V 

SQ 

MD 

SB 

EXPLANATION 

Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 

Rifting FORMATION NAMES V 

Volcanics SB Sabatayn Fm. 

HB Habshiyah Fm. AM Amran Group R Rus Fm. MD Madbi Fm. UR Umm er Radhuma Fm. SQ Shuqra Fm. MK Mukalla Fm. KH Kuhlan Fm. TW 

Tawilah Group GH Ghabar Group 

QN Qishn Fm. QB Qinab Group 

Figure 15. Petroleum system events chart for Madbi Amran/Qishn Total Petroleum System, Yemen. 
permeability values for the eastern basin Qishn sandstone wells. 

In the eastern basin, tectonic rejuvenation related to Tertiary rifting caused remigration and breaching of preexisting Jurassic 

reservoirs. Extensive leakage must have occurred as heavy oil 

belts are known to occur on the margins of the Qishn reservoirs 

(David Boote, oral commun., 2000, illustrated in fig. 11). 

Seal Rock 

Salt in the Shabwah Member (Tithonian) of the Sabatayn 

Formation forms the seal for the reservoirs in the Ma’Rib–Al 

Jawf / Shabwah basin (Seaborne, 1996). Salt sequences as much 

as 30 m thick have been observed in outcrops, but in places 

where the bases were not exposed (Beydoun and others, 1998). 

Brannin and others (1999) reported Sabatayn Formation salts as 

much as 1,500 m thick in the Amal field (fig. 1). The salt was 

mobilized shortly after deposition of the Nayfa (Naifa) Formation during Early Cretaceous time (fig. 12). Differential loading 

on the salt during sedimentation, as well as uplift of the Mukalla 

high, volcanism on the basin margins, and tilting of fault blocks 

associated with these activities, contributed to salt instability. 

The thickness of overlying formations, particularly the Nayfa 

and Qishn Formations, and Tawilah Group, is dependent on salt 

movement, thicker where salt withdrew and thinner over diapirs 

(fig. 12). 

In the Masila-Jeza basin, the salt is absent; thus, hydrocarbons generated from the Jurassic rifts migrate upward until they 

are trapped generally within the Qishn sandstone reservoirs 

beneath the Qishn carbonate unit (figs. 11, 13). The presence of 

degraded oils and heavy oils in some of these fields indicates 

that the seal in the eastern basin is less effective than the salt seal 

to the west. 

Overburden Rock 

Overburden rock includes the Cretaceous and younger 

post-rift fill. The Early Cretaceous Nayfa (Naifa) Formation is 

thus considered post-rift and the Upper Jurassic salt is considered syn-rift. This interpretation, as shown in figures 11 and 13, 

is consistent with that of Csato and others (2001). Brannin and 

others (1999) discussed two post-rift sequences: (1) Ayad, 

Sabatayn, and Naifa Formations, and (2) the Qishn Formation 

and Tawilah Group. In this report, the latter is considered to be 

post-rift and the former as syn-rift deposition. In areas where 

Tertiary rifting is predominant, as much as 4.5 km of post-rift 

overburden was deposited, such as in the Balhaf basin on the 

south end of the Ma’Rib-Al Jawf / Shabwah basin (fig. 3). Clastics of the Tawilah Group are the dominant sediments in these 

Tertiary rift grabens (figs. 4, 5), and more typical overburden 

depths are in the 1–2 km range in the western basin and 2–3 km 

in the eastern basin (figs. 4, 5, 12, 13). The earliest post-rift sediments are the transgressive Nayfa Formation clastics and carbonates that prograded generally from west to east, thinning to 

the west but crossing both basins. The clastic progradation and 

infilling of the Tawilah Group, principally from the west to east 

but including local sediment contributions from highs such as 

the Mukalla high, account for most of the sedimentary overburden (figs. 4, 5, 12). 

Hypothetical Total Petroleum Systems 

A Silurian-sourced petroleum system may also exist, particularly in northeastern Yemen. As shown in the Paleozoic 

stratigraphic column for Yemen (fig. 7), the preservation of Silurian and Infra-Cambrian sediments in the Qinab-1 well (fig. 5), 

particularly hydrocarbon source rocks, indicates the possibility 

of a Paleozoic or perhaps Infra-Cambrian petroleum system 

there. The Silurian Qusaiba source rock that extends over much 

of Saudi Arabia was identified in outcrop in the Wajid Plateau of 

southwestern Saudi Arabia, where it is as much as 60 m thick. 

Qusaiba strata may also have been encountered in Yemen in the 

Qinab-1 well on the north flank of the Hadramawt Arch on the 

southern flank of the Rub’Al Khali basin (Stump and van der 

Eem, 1994; Beydoun and others, 1998) (fig. 5). Although the 

potential may exist for a Silurian petroleum system in Yemen, 

the depth and thermal maturity of the Silurian Qusaiba shale for 

the southern Rub’ Al Khali basin indicate that it would be gasprone (Schenk and Pollastro, 2000). Assessment of the Paleozoic potential for the Rub’Al Khali portion of Yemen was 

included in the Qusaiba Silurian Total Petroleum System, and 

allocation of resources was made to Yemen (USGS, 2000). 

Immature source-rock intervals were identified in the 

Jurassic: Sabatayn Formation (Tithonian); the Cretaceous Nayfa 

(also spelled Naifa, Berriasian), Saar ( Berriasian), Qishn 

(Hauterivian-Barremian), Harshiyat (Albian-Aptian), Mukalla 

(Coniacian to Maastrichtian); and the Paleocene and Eocene 

Umm er Radhuma and Jeza Formations (Barnard and others; 

1992; Bott and others, 1992; Csato and others, 2001). 

Another Tertiary total petroleum system probably exists 

basinward (coastal and offshore areas) of the onshore MasilaJeza basin (fig. 13). Hydrocarbons have been produced from 

Tertiary strata in several wells, and are genetically distinct, with 

different gravity (both much higher and much lower) and higher 

sulfur content than the Jurassic-sourced hydrocarbons. This 

potential Tertiary TPS is evidenced by hydrocarbon shows in 

wells drilled offshore that tested oil from Oligocene and 

Miocene reservoirs (Richardson and others, 1994). The 

Sharmah-1 well in the Gulf of Aden (fig. 2), for example, produced 3,700 BOPD of 43° API gravity oil on a test from a middle Eocene carbonate (Beydoun, 1989). To 2001, however, 

commercial production has not been established in the Gulf of 

Aden from this hypothetical TPS. The high heat flow, as much 

as 26.5°C/100 m near the spreading center, indicates the existence of an oil window starting at depths from 2,438 to 2,743 m 

(from 8,000 to 9,000 ft) in the offshore of the Red Sea and Gulf 

of Aden (Beydoun, 1989; Barnard and others, 1992). In the 

onshore area, oil-prone source rocks of Tertiary age were 

identified in the Masilah-1 well (figs. 3, 5), but they showed only 

modest organic richness and fair pyrolysis yields, and were 

thermally immature (Barnard and others, 1992). 

Total Petroleum System 21 
Petroleum Assessment 

Production was first established in Yemen in 1984 but was 

not included in a previous assessment by the USGS (Masters and 

others, 1994). In the present assessment, only one assessment 

unit (AU), the Ma’Rib–Al Jawf / Shabwah / Masila AU 

(20040101), is identified within the Madbi Amran / Qishn TPS 

(200401) (fig. 1). Because the country and its petroleum provinces do not have a long discovery history, field growth is 

believed to be especially important for assessing future potential. 

Known oil reserves as of 1/1/96 were about 2 billion barrels of 

oil (BBO) (USGS, 2000). Known gas reserves as of 1/1/96 were 

about 11 trillion cubic feet of gas (TCF). The potential size of 

discovered fields using a field growth algorithm is shown in figures 16 and 17 as reported in USGS World Petroleum Assessment 2000 (USGS, 2000). 

The undiscovered resources estimated in this assessment 

are reported as probability distributions. It is therefore convenient to describe the results in terms of mean values and F95 

and F5 probability levels. The mean estimate of undiscovered 

oil is 2.7 BBO with a F95–F5 range from 1.0 to 4.7 BBO. 

The mean estimate of undiscovered natural gas is 17.0 TCF 

with a F95–F5 range of 6.5 to 30.0 TCF. The mean estimate 

of undiscovered natural gas liquids (NGL) is 0.9 billion barrels NGL (BBNGL) with a F95–F5 range of 0.4 to 2.2 

BBNGL. For known petroleum resource volumes, the 

Ma’Rib–Al Jawf basin province (province 2004) ranks 61st 

with 4.3 billion barrels of oil equivalent (BBOE), exclusive of 

U.S. provinces. When undiscovered potential is added to 

known reserves, the total petroleum endowment for the Madbi 

Amran / Qishn TPS rises to 9.8 BBOE, which then ranks 

Yemen 51st for potential of petroleum resources, exclusive of 

the U.S. The estimated number and sizes of undiscovered oil 

and gas fields for the Ma’Rib–Al Jawf / Shabwah / Masila AU 

(20040101) are shown in figures 18 and 19. 

Although Yemen is a relatively immature petroleumproducing country from an exploration standpoint, sizes of 

discovered fields already show significant decline. However, 

the undiscovered potential, at the mean, was viewed to be larger 

than what has been discovered to time of this report. The potential resides principally in combination structural/stratigraphic 

traps related to the complex interplay of rift-filling sequences 

within multiple grabens, half-grabens, and horsts. In the 

Ma’Rib–Al Jawf / Shabwah basin, petroleum traps associated 

with salt tectonics provide many trapping styles. Intra-salt and 

supra-salt reservoirs are considered viable plays and are being 

actively explored. In the Masila-Jeza basin, rejuvenation of 

basement extensional fault blocks, as well as some transpressional features with associated stratigraphic/structural traps, will 

likely result in future discoveries. 

The potential for undiscovered oil and gas resources in 

the Mesozoic Nayfa (Naifa) petroleum system was not 

assessed, but the limited areal extent of potential source rocks 

and their shallow depth of burial and concomitant immaturity 

(Csato and others, 2001) make its hydrocarbon potential 

relatively limited. 

22 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 
CUM. GROWN OIL VOLUME (MMBO)


Ma'Rib–Al Jawf/Shabwah/Masila, Assessment Unit 2

4,000 3,500 3,000 2,500 2,000 1,500 1,000 

500 

0 

1980 1982 1984 1986 1988 1990 1992 1994 

FIELD DISCOVERY YEAR 

Petroleum Assessment Figure 16. Cumulative grown oil volumes versus discovery year for Yemen assessment unit (from USGS, 2000). 23
 
24
 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen 

CUM. GROWN GAS VOLUME (BCFG)


Ma'Rib–Al J

awf/Shabwah/Masila, Assessment Unit 2

25,000 20,000 15,000 10,000 

5,000 

0 

1980 1982 1984 1986 1988 1990 1992 1994 

FIELD DISCOVERY YEAR 

Figure 17. Cumulative grown gas volumes versus discovery year for Yemen assessment unit (from USGS, 2000). 
Ma'Rib–Al Jawf/Shabwah/ Masila, Assessment Unit 

Undiscovered Field-Size Distribution 

Minimum field size: 5 MMMean number of undiscovered fields: 71.5 

25
 

UNDISCOVERED OIL FIELDS (No.) 20
 15
 10
 5
 

0
 

4-<8 8-<16 16-<32 32-<64 

64-<128 128-<256 256-<512 512-

<1024 

Figure 18. Estimated undiscovered oil field number and size distribution for Madbi Amran/Qishn Total Petroleum System, Yemen (from USGS, 20

Petroleum Assessment OIL FIELD SIZE (MMBO)
25
 
26
 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen Ma'Rib–Al Jawf/Shabwah/ Masila, Assessment Uni

Undiscovered Field-Size Distribution 14
 12
 Minimum field size: 

Mean number of undiscovered fields

UNDISCOVERED GAS FIELDS (No.) 10
 8
 6
 4
 

2
 0
 

24-<48 48-<96 96-<192 192-<384 384-<768 768-

<1536 


1536-


<3072
 

3072-


<6144
 

GAS FIELD SIZE (BCFG)


Figure 19. Estimated undiscovered gas field number and size distribution for Madbi Amran/Qishn Total Petroleum System, Yemen (from USGS, 2
References Cited 

Ahlbrandt, T.S., Charpentier, R.R., Klett, T.R., Schmoker, J.W., and 

Schenk, C.J., 2000, Analysis of assessment results, Chapter AR in 

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28 Total Petroleum System, Ma’ Rib–Al Jawf / Shabwah, and Masila-Jeza Basins, Yemen