Arabian Plate Chronostratigrahic Maps

Chronostratigraphic Isopach
mapping of sequences of the
Arabian Plate: Product and
Process
By Walter H. Pierce
And
Everett Rutherford
Of
STARTEXP
October 2009

• StartExp is a group of independent consultants with more than 80
years of combined hydrocarbon exploration and production
experience. We have worked in most parts of the world, with
particular emphasis on Africa, the Middle East and Central Asia.

• We provide products and consulting services that form an integrated
technical framework for improving decision making in selecting
acreage for hydrocarbon exploration. While our current databases
and initiatives are not designed for the individual prospect scale, our
methods are scale-independent and can be applied on whatever
level available data allows.

• Our principal tools include potential fields data, remote images,
surface geology, basin modeling, and a variety of in-house regional
surface and subsurface data sets. Additional data may be
contributed by the client. All project elements are assembled in a
GIS framework designed to assist exploration ventures.

• For more information please visit: http://startexp.com/

STARTEXP
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W alter H. Pierce and Everett Rutherford

Problems and Talk Objectives
• Point out selected new discoveries in stratigraphic context
• Mapping across nomenclature changes and country
boundaries.
• Mapping chronostratigraphic sequences versus
Formations.
• Pay attention to zero-edge accuracy
– maps will be used for sub crop, worm’s eye, subsidence
• Process that is updateable and adaptable.
• Show process and “bag of tricks
bag tricks.”
• Show products

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Talk Organization
• Preliminary View of Products
• Scale and Database
• Surface Geology Constraint
• Queries
– wells spudding in sub crop (Red
Red)
– wells with interval missing in subsurface (White)
– Wells with thicknesses (Black)
– Wells with penetrations (Gray and Yellow)
• Construction of Composite Table for Mapping
• Quality Control
• Review of Products and importance of specific maps

STARTEXP

Comparison of scale
of Arabian Plate
versus
lower 48

ST ART EX P
http:// S tartex p.c om
W alter H. Pierc e and Everett Rutherf ord

Map distribution
Of
Database

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Database
• 2819 wells
– mappable
– 2 or more tops in well
• 46,911 tops records
– mappable
• 481 unique ages
• ~ 600 unique lithostratigraphic units.

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Assigning Ages to Tops
• The process begins with assigning a 9 digit code
to stratigraphic names.
– Attempt to have the code relate to age and superposition.
• A spreadsheet - database cycle focuses on
code superposition problems.
• Repeat cycle, adjust, repeat .. And so on... until
codes obey superposition.
• Finally 9 digit codes are converted to absolute
ages.

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A B C D E F
Well Formation Depth Sequence Shifted Subtract
Code Sequence E from D
Code
1 Dukhan 1 Dammam 0 201000000
2 Dukhan 1 Umm Er Raduma 300 202000000 201000000 1000000
3 Dukhan 1 Simsima 500 301000000 202000000 99000000
4 Dukhan 1 Mishrif 1000 304000000 301000000 3000000
5 Dukhan 1 Ahmadi 2000 305000000 304000000 1000000
6 Dukhan 1 Nahr Umr 4000 307000000 305000000 2000000
7 Dukhan 1 Shuaiba 4500 401000000 307000000 94000000
8 Dammam 1 Rus 0 203000000 401000000 -198000000
9 Dammam 1 Umm Er Raduma 200 202000000 203000000 -1000000
10 Dammam 1 Simsima 600 301000000 202000000 99000000
11 Dammam 1 Mishrif 1000 304000000 301000000 3000000
12 Dammam 1 Ahmadi 2000 305000000 304000000 1000000
13 Khurais 1 Dammam 0 201000000 305000000 -104000000
14 Khurais 1 Rus 100 203000000 201000000 2000000
15 Khurais 1 Umm Er Raduma 300 202000000 203000000 -1000000
16 Khurais 1 Simsima 1000 301000000 202000000 99000000
17 Khurais 1 Mishrif 2000 304000000 301000000 3000000
18 Khurais 1 Ahmadi 4000 305000000 304000000 1000000
19 Khurais 1 Nahr Umr 3500 307000000 305000000 2000000
307000000

Spreadsheet - Database Cycle
for correcting superposition problems

2
1 Use Database to
Shift and Subtract Query out smaller
Sequence Code Negatives to find
in Spreadsheet Superposition
Up To Problems
6 cycles

3
Prioritize and
Adjust
Sequence Codes
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Graph of
Stratigraphic
Database showing
Number of Well
cuts through each
age:
Arabian Plate
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Using Surface Geology to
constrain mapping
• A grid of points has been run through each
surface geology polygon.
• By putting the grids into a database we make
composites of sub crop geology at System level to
constrain isopach mapping.

STARTEXP

Database of Surface Geology Points created to
enable constraint of isopach zero edges

STARTEXP Based on USGS geology

Query (RED)
(RED)
for wells that spud in sub crop
• Query out wells that have a minimum age
older than the earliest age of the interval to
be mapped.
• Give these wells a thickness value of -11

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Query to find wells that spud below interval:
Plotted as red symbols given value of -10 for
gridding

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Query (WHITE)
for wells missing tops from the
interval to be mapped
• For wells that have records older and younger
than the interval.
• Remove records that are younger or older than
interval to be mapped.
• Count remaining records for each well.
• Assign thickness value of -5 to wells that have no
records.
• Plot these wells as white dots.

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Query to find wells with subsurface pinch outs:
Plotted as white symbols given value of -5 for
gridding

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Dual Query System:
First Thickness Calculation
• From the set of wells that have records younger
and older than the interval.
• Find the maximum and minimum depth record for
each well within the interval and subtract the
minimum depth from the maximum depth. Then
store this result as a table.

STARTEXP

Dual Query System:
Second Thickness Calculation
• From the set of wells that have records above and
below the interval.
• From well top records with ages within the
interval, find the minimum depth for each well.
• From a set of well top records with ages older
than the interval find the minimum depth.
• Subtract the smaller depth from the larger depth.

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Dual Query System for Sequence Thickness

Query 1 Query 2
TOP

1) Match depths to time.

2) Calculate thickness
TIME for Query 1 and Query 2.

3) Subtract for error checking

4) Filter out problem wells.

5) Take maximum thickness.

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Stratigraphic Thickness Elevation Plot for Upper and
Middle Jurassic

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Penetration wells:
GRAY & YELLOW
• Wells that do not penetrate entire sequence
• Find by query.
• Adjust for :
– Zero edge extension
– Depocenters

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Query to find wells with penetrations that impact
interpretation: Plotted as value of penetration and given
yellow symbol. Gray symbol designates wells that
penetrate but do not impact interpretation.

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Composite
Sub-crop Table for Surface
Wells Grid Outcrop

Missing in
Subsurface
Wells

Thickness
Calculation
Wells

Penetration
Penetration Wells
Action
Wells
Two Judgments
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Contrast of Maps showing thickness
constraints only with system used in this
Study : Upper and Middle Jurassic example

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Quality Control
• Superposition and age assignment
• Step Plots
• Dual thickness query
• Laying on map for comparison (five query products)
– surface map sub crop
– wells spudding in sub crop
– interval missing in subsurface
– wells with thickness calculation (Dual Query)
– wells with penetration and taking selective action
– mapping result
• Filters
– 1) data quality and 2) structural repeats

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Begin Slide Show of Maps

We have posted some interesting
new wells and discoveries in RED
on specific maps

STARTEXP
Walter H. Pierce and Everett Rutherford

Slide Show of sequences of the
Arabian Plate
The show is a series of maps each preceded
by a slide which gives my “cliff note” version of
what is important in so far as hydrocarbon geology
concerning each chronostratigraphic sequence.
The progression is down-section.

Watch control. Remember:
Black = thickness = variable
Dusky Red area = sub crop outcrop = -10
White = subsurface missing = -5
Red = well sub crop spud = -11
Gray = well penetration
Yellow = well penetration with action = variable

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Importance of Neogene

• Evaporite Seal for Zagros Dezful and Northern
Iraq
• Subsidence-Driven Maturation along the
Northwest boundary of Arabian Plate

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Neogene
Isopach


Importance of Oligocene

• BIG OIL: Provides major reservoir (Asmari)
for Zagros and Iraq.
• Note restricted distribution sandwiched
between Neogene above and Paleocene-
Eocene below.
• Where will the first major stratigraphic
discovery be made?

STARTEXP

Oligocene
Isopach


Importance of Paleocene-Eocene
Paleocene-
● Tawke-1
Tawke- ● Shakal-1
Shakal-

• Broad regional subsidence brings vast area
to regional threshold of maturation.
• Source of gas and oil in northern Dezful
embayment of Iran.
• Behaves as vertical carrier system
– Note isopach thin in area of Kirkuk, northern Iraq
may have aided focusing of carrier system

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Eocene and
● Tawke-1
Tawke- Paleocene
Isopach
● Shakal-1
Shakal-


Importance of Upper Cretaceous
● Tawke-1 ● Bina-Bawi-1 ● Miran West-1
Tawke- Bina-Bawi- West-

• Many individual Basins differentiated, for
example the Euphrates Graben.
• Major OIL: Majnoon
• Three or more distinctly aged source units.
• Difficult to correlate.
• Under-explored.

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Upper
● Tawke-1
Tawke- Cretaceous
● Bina-Bawi-1
Bina-Bawi- Isopach
● Miran West-1
West-


Importance of Middle Cretaceous

• BIG OIL: Burgan, Safaniya Sandstone
Reservoirs
• Source Rock
• Important carbonate reservoirs

STARTEXP

Middle
Cretaceous
Isopach


Importance of Lower Cretaceous

• BIG OIL: Zubair sandstone reservoirs,
Shuaiba carbonate reservoirs, Thamama
carbonate reservoirs.
• Sleeper Sequence: overlooked carbonate
reservoirs and source rock
• Problem: producing multiple thin reservoirs

STARTEXP

Lower
Cretaceous
Isopach


Importance of Upper and Middle
Jurassic
● Shaikan-1
Shaikan- perhaps most important recent discovery because
It establishes Jurassic reservoir rock in Iraq

• BIG OIL: Ghawar and other Saudi fields,
carbonate reservoirs
• source rock, reservoirs, seals
• At just the right burial depth for a large part
of Basin

STARTEXP

Upper and
Middle Jurassic
● Shaikan-1
Shaikan-
Isopach


Importance of Lias and Triassic
● Bina-Bawi-1
Bina-Bawi- non commercial gas test and Shaikan-1 oil test?
Shaikan-

• Immature exploration except for Syria and
Northern Iraq.
• Oil and gas reservoirs, carbonate
• Further potential in Turkey, Jordan, and
Israel
– potential for small companies
• Source rock, seals, and reservoirs
• Frontier
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Lias and
Triassic
● Shaikan-1
Shaikan-
● Bina-Bawi-1
Bina-Bawi- Isopach


Importance of Permian

• BIG GAS: North Dome, North Pars, South
Pars, etc. carbonate reservoirs, anhydrite
seals. See http://en.wikipedia.org/wiki/File:Iran_Gas_Fields_Location.GIF)
• Basal sandstone reservoirs in Saudi Arabia
and Oman oil play, red bed seals
• Sourced from below: Silurian and late
Precambrian and Cambrian, across
unconformity
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Permian
Isopach


Importance of Carboniferous

• Almost restricted to Syria
• Significant gas reservoirs
• Possible gas source: coals
• Observe impact of Hercynian erosion or non-
deposition on isopach distribution of
Carboniferous, Devonian, Silurian, and
Ordovician.

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Carboniferous
Isopach


Importance of Devonian

• Major Gas reserves in deep Ghawar could
become a major gas and oil play on the
Arabian Plate
• Definitely “Frontier”
• Near shore marine sand and carbonate
reservoirs.

STARTEXP

Devonian
Isopach


Importance of Silurian
● Arpatepe-1
Arpatepe- ● Akkas-
Akkas-1

• Major Source rock interval
– multiple intervals, wide spread
• Source of both oil and gas
• Sandstone reservoirs at Akkaz, western
Iraq
• Seal sequence with potential underlying
Ordovician sandstone reservoirs.

STARTEXP

● Arpatepe-1
Arpatepe- Silurian
Isopach
● Akkas-
Akkas-1
● Risha-
Risha-1


Importance of Ordovician
● Arpatepe-1
Arpatepe- ● Akkas-
Akkas-1

• Frontier
• Gas Production at Risha in western Jordan
• Shows of oil and gas in Turkey
• Facies: sandy in south grading to more fine-
grained to north.

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● Arpatepe-1
Arpatepe-
Ordovician
Isopach

● Akkas-
Akkas-1
● Risha-
Risha-1


Importance of Cambrian

• Late Precambrian
• Oman
• Source rock (very rich and thick, Salt, salt-
related trapping and salt tectonics
• See “Half Graben” on isopach

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Cambrian
Isopach


Importance of Precambrian
• Infracambrian
– Hormuz salt “structure maker”
– Huqf Group source rocks (silicilyte
facies)
• “Basement” Reservoirs
– Yemen
• Large oil columns and reserves
• Multiple fields and prospects
– Egypt

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Subsurface
Precambrian in
yellow,
Precambrian
outcrop in dark
brown, young
oceanic crust in
blue, young
Egypt/GOS
volcanic in
basement magenta
discoveries Yemen
Basement
discoveries

Precambrian

Basement Play in Yemen

Schlumberger

The End

PostScript:
If you would like a file of
the narrative to go with these slides send and email request to
walterhpierce@startexp.com

STARTEXP

Arabian Plate Chronostratigrahic Maps

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