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Assessment Unit 20040101
45 50

Saudi
Arabia Geologic Summary
Detailed map of this assessment unit
Exploration/Discovery-History Data
Plots of Known Field Sizes
2004
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# Plots of Grown Resources
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Tables
Sanaa # #
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# 2006 Assessment Input Data
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Assessment Results
Yemen Assessment Unit Summary
Detailed Assessment Results
Aden
Undiscovered Field-Size Distributions
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Arabian
Sea
0 100 200 KILOMETERS

Ma'Rib-Al Jawf/Shabwah/Masila Assessment Unit 20040101

Ma'Rib-Al Jawf/Masila Basin Geologic Province 2004
Other geologic province boundary

U.S. GEOLOGICAL SURVEY WORLD PETROLEUM

ASSESSMENT 2000— DESCRIPTION AND RESULTS
U.S. Geological Survey World Energy Assessment Team
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USGS PROVINCE: Ma'Rib-Al Jawf/Masila Basin (2004) GEOLOGIST: T.S. Ahlbrandt

TOTAL PETROLEUM SYSTEM: Madbi Amran/Qishn (200401)

ASSESSMENT UNIT: Ma'Rib-Al Jawf/Shabwah/Masila (20040101)

DESCRIPTION: Assessment unit encompasses the entire Total Petroleum System and crosses
three provinces in Yemen. The petroleum system is related to an Upper Jurassic source rock
sequence essentially deposited as deep marine deposits in a synrift setting (in some areas prerift
sag). In the western part of the area, reservoirs are synrift, in the eastern part reservoirs are
postrift.

SOURCE ROCKS: The Upper Jurassic (Kimmeridgian) source rocks of the Madbi Formation
including both Madbi and Lam Members are organic-rich black shales deposited in the deeper
portions of rifts in the Late Jurassic.

MATURATION: Source rocks began generating in the central rift basin in latest Cretaceous to
earliest Paleogene time and the process was largely completed by the end of Paleogene time.

MIGRATION: Oil and gas migrated along faults to horst blocks within these various basins.
Numerous horst uplifts occur; however migration resulted in hydrocarbon accumulations in those
areas where sealed by either a Jurassic salt (Ma’Rib/Al-Jawf/Shabwah or Sab’atayn basin) or by
Early Cretaceous carbonate (Masila/Jeza or Say’un basin). Heavy oil is known to occur marginal
to the accumulation sites.

RESERVOIR ROCKS: In the western basins (Ma’Rib/Al-Jawf), the reservoirs are dominantly
Upper Jurassic (Kimmeridgian, Tithonian) clastics of the Amran Group (Safir Member), or lesser
amounts of carbonates in the Amran Group. The Safer/Alif/Yan Member clastics prograded
from the northwest of the Ma’Rib Basin and diminish in thickness and content to the southeast;
they are largely absent in the southern Shabwah Basin. In the Masila/Jeza Basin, the Early
Cretaceous estuarine sandstones of the Qishn Formation (Berremian/Aptian) are the primary
reservoir.

TRAPS AND SEALS: Salt of the Upper Jurassic (Tithonian) Shabwa Member are the critical
seal within the Ma’Rib, Al-Jawf, and Shabwah basins, a secondary seal are evaporites of the
Avad and Nayfa Formations. The Qishn Carbonate Member (Aptian) provides the seal for the
underlying Qishn Clastic Member in the Masila Basin.

REFERENCES:
Bosence, D.W.J., ed., 1997, Special issue on Mesozoic rift basins of Yemen: Marine and
Petroleum Geology, v. 14, no. 6, p. 611-730.
Beydoun, Z.R., and others, 1998, International lexicon of stratigraphy, v. III, Republic of Yemen,
(2nd ed.): International Union of Geological Sciences and Ministry of Oil and Mineral
Resources, Republic of Yemen Publication no. 34, 245 p.
Brannin, Joe, and others, 1999, Geological evolution of the central Marib-Shabwa basin, Yemen:
GeoArabia, v. 4, no. 1, p. 9-34.

U.S. GEOLOGICAL SURVEY WORLD PETROLEUM

ASSESSMENT 2000— DESCRIPTION AND RESULTS
U.S. Geological Survey World Energy Assessment Team
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ASSESSMENT 2000— DESCRIPTION AND RESULTS
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46 48 50
2019 Saudi 2010
Arabia
16

20040101
2009
2004

Yemen
2007

14 2101
2006

100 KILOMETERS Gulf of Aden

Ma'Rib-Al Jawf/Shabwah/Masila
Assessment Unit - 20040101
EXPLANATION
Hydrography
Shoreline
2004 Geologic province code and boundary
Country boundary
Gas field centerpoint Assessment unit
Oil field centerpoint 20040101
code and boundary
Projection: Robinson. Central meridian: 0
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SEVENTH APPROXIMATION
NEW MILLENNIUM WORLD PETROLEUM ASSESSMENT
DATA FORM FOR CONVENTIONAL ASSESSMENT UNITS

Date:………………………….. 5/12/99
Assessment Geologist:…….. T.S. Ahlbrandt
Region:……………………….. Middle East and North Africa Number: 2
Province:……………………… Ma'Rib-Al Jawf/Masila Basin Number: 2004
Priority or Boutique.………… Priority
Total Petroleum System:…… Madbi Amran/Qishn Number: 200401
Assessment Unit:…………… Ma'Rib-Al Jawf/Shabwah/Masila Number: 20040101
* Notes from Assessor

CHARACTERISTICS OF ASSESSMENT UNIT

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

What is the minimum field size?………. 5 mmboe grown (>1mmboe)

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

Number of discovered fields exceeding minimum size:………… Oil: 36 Gas: 15

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

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

1st 3rd 85.8 2nd 3rd 67.9 3rd 3rd 31.9
Median size (grown) of discovered gas fields (bcfg):
1st 3rd 976.7 2nd 3rd 1135 3rd 3rd 77.8

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) 10 median no. 70 max no. 140

Gas fields:……………………………….min. no. (>0) 10 median no. 35 max no. 60

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 5 median size 23 max. size 600
Gas in gas fields (bcfg):…………………... min. size 30 median size 100 max. size 3000

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ASSESSMENT 2000— DESCRIPTION AND RESULTS
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Assessment Unit (name, no.)

Ma'Rib-Al Jawf/Shabwah/Masila, 20040101

AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS

(uncertainty of fixed but unknown values)
Oil Fields: minimum median maximum
Gas/oil ratio (cfg/bo)………………………...……… 2000 4000 6000
NGL/gas ratio (bngl/mmcfg)…………………....…. 30 60 90

Gas fields: minimum median maximum

Liquids/gas ratio (bngl/mmcfg)….…………..…….. 22 44 66
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)…………………….…………. 19 36 45
Sulfur content of oil (%)………………………...….. 0.1 0.25 0.54
Drilling Depth (m) ……………...…………….…….. 750 2500 4000
Depth (m) of water (if applicable)……………...….. 0 0 100
* V-12, 19, 2.3, 25, 26 V-2-26ppm
* Ni-6, 7, 1.3, 5.0, 11 Ni-6-11ppm
Gas Fields: minimum median maximum
Inert gas content (%)……………………….....……
CO2 content (%)……………………………….....…
Hydrogen-sulfide content (%)………………...…….
Drilling Depth (m)…………………………………… 750 3000 5000
Depth (m) of water (if applicable)…………………. 0 0 100

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ASSESSMENT 2000— DESCRIPTION AND RESULTS
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Assessment Unit (name, no.)

Ma'Rib-Al Jawf/Shabwah/Masila, 20040101

ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT

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

1. Yemen 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):… 100
Portion of volume % that is offshore (0-100%)…… 1

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%)…… 1

2. Province 2004 represents 21.2 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

Richness factor (unitless multiplier):……….…..…
Volume % in parcel (areal % x richness factor):… 35
Portion of volume % that is offshore (0-100%)…… 0

Gas in Gas Fields: minimum median maximum

Richness factor (unitless multiplier):…………..….
Volume % in parcel (areal % x richness factor):… 35
Portion of volume % that is offshore (0-100%)…… 0

3. Province 2006 represents 39.4 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

Richness factor (unitless multiplier):……….…..…
Volume % in parcel (areal % x richness factor):… 25
Portion of volume % that is offshore (0-100%)…… 5

Gas in Gas Fields: minimum median maximum

Richness factor (unitless multiplier):…………..….
Volume % in parcel (areal % x richness factor):… 25
Portion of volume % that is offshore (0-100%)…… 5

4. Province 2009 represents 39.4 areal % of the total assessment unit

Oil in Oil Fields: minimum median maximum

Richness factor (unitless multiplier):……….…..…
Volume % in parcel (areal % x richness factor):… 40
Portion of volume % that is offshore (0-100%)…… 0

Gas in Gas Fields: minimum median maximum

Richness factor (unitless multiplier):…………..….
Volume % in parcel (areal % x richness factor):… 40
Portion of volume % that is offshore (0-100%)…… 0

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ASSESSMENT 2000— DESCRIPTION AND RESULTS
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Ma'Rib-Al Jawf/Shabwah/ Masila, AU 20040101

Undiscovered Field-Size Distribution
25

Minimum field size: 5 MMBO

UNDISCOVERED OIL FIELDS (No.)

20 Mean number of
undiscovered fields: 71.5

15

10

0
4-<8 8-<16 16-<32 32-<64 64-<128 128-<256 256-<512 512- 1024- 2048-
<1024 <2048 <4096
OIL-FIELD SIZE (MMBO)

U.S. GEOLOGICAL SURVEY WORLD PETROLEUM

ASSESSMENT 2000— DESCRIPTION AND RESULTS
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Ma'Rib-Al Jawf/Shabwah/ Masila, AU 20040101

Undiscovered Field-Size Distribution
14

Minimum field size: 30 BCFG

12
UNDISCOVERED GAS FIELDS (No.)

Mean number of
undiscovered fields: 35
10

0
24-<48 48-<96 96-<192 192-<384 384-<768 768- 1536- 3072- 6144- 12288-
<1536 <3072 <6144 <12288 <24576

GAS-FIELD SIZE (BCFG)

U.S. GEOLOGICAL SURVEY WORLD PETROLEUM

ASSESSMENT 2000— DESCRIPTION AND RESULTS
U.S. Geological Survey World Energy Assessment Team