northwest africa atlantic...
TRANSCRIPT
Ben Sayers
Northwest Africa Atlantic Margin – MSGBC Basin Prospectivity
Project Developer – Africa, Mediterranean & Middle East 27th May 2015
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Contents
Introduction
Geological Evolution of the MSGBC Basin
Exploration History
NWAAM Survey
Location and Acquisition
Play concepts and thermal modelling
Data Examples
Guinea Conakry
Guinea Bissau
AGC
Senegal/The Gambia
Mauritania
Summary
Conclusions
3
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Geological Evolution of the MSGBC Basin
4 4
5
Mauritania, Senegal,
Gambia, Bissau, Conakry
(MSGBC)
Basin
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Basin Evolution
The pre-rift section is made up of:
• Palaeozoic extensional tectonics in the south with horsts, grabens and tilted fault
blocks preserved from Pre-Hercynian; and
• Compressional tectonics in the north and central parts of the basin with effects
of Hercynian and Caledonian orogenies.
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Basin Evolution
• The basin was formed at the end of the Permian in a Triassic Rift system.
• Lacustrine source rocks were deposited followed by continental Triassic clastics
1500m thick.
R
Triassic
R
Triassic
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Basin Evolution
• A thick sequence of Triassic/Early Jurassic evaporites were deposited in the basin.
Up to 2000m of salt.
• Transgressing seas brought post-rift marine sediments.
R
Triassic
Early Jurassic
Early Jurassic
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Basin Evolution
• 2000-3000m thick carbonates reservoirs were deposited form an active carbonate
factory.
• The platform both prograded and regressed through time.
R
Triassic
Early Jurassic
R
Mid-Jurassic
R
Mid-Jurassic
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Basin Evolution
• Thick marine shales interbedded with marginal marine sandstones
deposited after the opening of the Atlantic in the Cenomanian.
• Black, bituminous Turonian shales were deposited marking the
maximum Cretaceous transgression
Mid-Cretaceous
R
Triassic
Early Jurassic
R
Mid-Jurassic
Mid-Cretaceous
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Basin Evolution
• Senonian marine regression which culminated in deposition of
thick Maastrichtian sandstones. Up to 1200m thick.
• Tertiary sediments are unconformable and consist of marine
shales, carbonates with influx of sandy turbidites
R
Upper Cretaceous/Tertiary
R
R
Triassic
Early Jurassic
Mid-Jurassic
Mid-Cretaceous
R
Upper Cretaceous/Tertiary
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Basin Evolution R
R
Mid-Cretaceous
Triassic
Early Jurassic
Mid-Jurassic
R
Upper Cretaceous/Tertiary
The Basin has undergone a complex history that can be divided
into 3 main stages of development:
• the pre-rift (Precambrian to Paleozoic)
• syn-rift (Permian to Early Jurassic)
• post-rift (Middle Jurassic onwards)
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Exploration History
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Adapted from Grant et al. 2013. Copyright SIEP BV.
FAN-1
SNE-1
(Source FAR website)
To date 177 exploration wells have been drilled in the basin with 115
encountering hydrocarbons – 66%!
Of the 110 offshore wells:
only 60 are in water depth of greater than 100m;
only 30 in water depths greater than 1000m;
And only 2 in water depths greater than 2000m.
Drilling Summary
14 14
100
MMBOE
950
MMBOE Avg. sized
Discovery
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NWAAM Survey
15 15
Acquired in collaboration with:
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NWAAM Survey
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NWAAM
Ph1
NWAAM
Ph2
NWAAM Phase 1
Acquisition April – October 2011
Covered Area 220,000 km2
NWAAM Phase 2
Acquisition May - November 2012
Covered Area 140,000 km2
NWAAM Survey
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NWAAM
Ph1
NWAAM
Ph2
NWAAM Survey
Streamer Length:
8km
Recording Chs:
640
Record Length:
14 sec (NWAAM Ph2)
9 sec (NWAAM Ph1)
More info: http://www.tgs.com/
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M. Brownfield and R. Charpentier, 2003
PR
E-R
IFT
NWAAM Regional Stratigraphy
SY
N-
RIF
T
PO
ST-R
IFT
E
AR
LY
PO
ST
-
RIF
T
R
R
Source rocks
Clastic reservoir
Limestone reservoir
Silurian MARINE SOURCE ROCK ?
Devonian RESERVOIR
Triassic LACUSTRINE SOURCE ROCK ? Triassic RESERVOIR
Cenomanian / Turonian MARINE SOURCE
ROCK
Cretaceous – Tertiary RESERVOIR
Jurassic
Cenomanian
Cre
tace
ous
Maastrichtian
Triassic
Aptian MARINE SOURCE ROCK
Albian RESERVOIR
R
R
R
R
R
R
R
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Play Concepts
Silurian Sourced Possible: Silurian present across majority of North
Africa and Paleozoic sandstones (15-20% Ф)
present in Bove Basin along with 400m thick
Silurian “Buba Shale” source rock
Triassic Hypothetical: Lacustrine sources charging
Triassic clastics sub-salt. Works in
Morocco and Newark basin
Aptian-Albian PROVEN: FAN-1 and SNE-1
Turonian/Cenomanian Sourced PROVEN: Lots of wells including – Jammah-1 GB-1, Sabu-1, Sheepshead-1
Jurassic Carbonate Reservoir PROVEN: Offshore Cape Timiris-1, Loup de mer-1
Buried Hills
Buried Hills PROBABLE: Albian shelf eroded by Senonian unc., karstified, then sealed
by upper Cretaceous to lower Tertiary shales & marls. Evident on Seismic Miocene Sources Hypothetical: Shales deposited and Miocene
reservoirs are proven so would just require
sufficient burial
Salt related Salt traps and structures are proven
throughout the basin. Chinguetti Field etc…
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NWAAM Data Play Examples
21 21
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Coppolani-1 well was un-economical discovery. Oil found in the Maastrichtian, charged
Type II Turonian oil.
NWAAM - Mauritania Sub Basin
Top Syn-Rift
Sea Bed
Top Lower Miocene
Senonian Unc.
Top Turonian
Top Neocomian
Top Sag
Top Aptian
Eocene-Oligocene
Carbonates
Syn-kinematic
sand deposition?
Lower Aptian-
Neocomian updip
brightening
Salt-related sand
deposition?
Analogous to
Labeidna field?
Analogous to
Chinguetti field?
Senonian Unc.
Sea Bed
Top Lower Miocene
Top Turonian
Coppolani-1
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NWAAM – Southern Mauritania Sub Basin
E W Faucon-1 WD = 1164m TD= 4170m
• Salt diapir creates traps for updip migration
• Faucon-1 drilled HC bearing sandstones from the Lower Campanian
• Salt present throughout the majority of the basin.
Sea Bed
Senonian Unc.
Top Turonian
Top Aptian
Top Neocomian
Top Jurassic
Top Lower Miocene
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• 2 recent discoveries in the basin, both Albian sandstone reservoirs sourced from
Aptian sources.
• FAN-1 is a set of stack fans
• SNE-1 - 96 metre oil column in 24% PHIE shelf edge sands
• FAN-1 & SNE-1 have a combined p-50 reserve estimate of over a Billion barrels
of Oil of API 32°
NWAAM – Sangomar Basin
TW
T (s
ec)
E W
FAN-1 WD = 1427m TD= 4927m
SNE-1 WD = 1100m TD= 3000m
Top Syn-Rift
Sea Bed
Top Albian
Top Oligocene
Top Jurassic
Top Senonian
Image credit: Cairn Capital Markets Day, 11th May 2015
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• Similar structuration to Sangomar basin despite being 150km further south
• SNE-1 analog further up-dip which has an AVO response showing stacked sands.
• Salt dome post-salt clastic play?
• Evidence of Pre-salt Triassic play
NWAAM – Casamance Basin
E W
Triassic source
rocks?
FAN-1 analogue
SNE-1 analogue
8km
Top Syn-Rift
Sea Bed
Top Albian
Top Oligocene
Top Jurassic
Top Senonian
Top Aptian
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• Contractional structures and fault bounded brightening
• Salt tectonics have controlled sand deposition
• Amplitude anomalies in the Lower Albian related to HC charge or high porosity sands
Cenomanian
source interval
HC related
brightening?
Fault bounded updip
brightening
TW
T (
se
c)
NWAAM - Casamance Sub Basin (AGC)
Top Syn-Rift
Sea Bed
Top Albian
Top Jurassic
Top Aptian
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• Hydrocarbon Related Diagenetic Zones (HRDZ) indicate a highly charged
hydrocarbon system.
• Aptian-Albian sediments pinching out against the Jurassic carbonate platform
and showing high amplitude anomaly.
• Aptian sand channels pinching out over the flank of salt.
Albian-Aptian sands
Updip brightening or charged sands Salt dome
Aptian channel sands with
updip pinchout over flank
of salt diapir
HRDZ?
NWAAM - Southern Sub Basin (Guinea Bissau)
Top Syn-Rift
Sea Bed
Top Albian
Top Oligocene
Top Jurassic
Top Senonian
Top Aptian
Sea Bed
Top Albian
Top Oligocene
Top Senonian
Top Aptian
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N S T
WT
(se
c)
• Diapir piercing Late Cretaceous sediments.
• shallow water sub-crop unconformity traps at the edge of the hinge zone.
• syn-rift sands below the salt.
Syn-Rift sands?
Sub-crop
unconformity traps
Salt related
structures
NWAAM - Southern Sub Basin (Guinea Bissau)
Top Aptian
Top Albian
Top Jurassic
Top Syn-Rift
Top Oligocene
Top Senonian
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• Thinner Mesozoic sediments due to basement geometry.
• Triassic source rocks in oil window
• Possible evidence of presence of Silurian sources and Devonian clastics
TW
T (s
ec)
Pre-rift
Sediments
NWAAM - Offshore Guinea Conakry
N S
Early syn-rift
Sediments
Top Aptian
Top Jurassic
Top Syn-Rift
Top Oligocene
Top Senonian
Sea Bed
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Northern Sierra Leone
A series of Mid-Albian (syn-rift) fault terraces with some bright amplitudes
within the fault blocks that relate to sand-prone sequences within the syn-rift
sediments.
Top Aptian
Top Cretaceous
Base Neogene
Sea Bed
Top Miocene
Top Eocene
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E W
NWAAM – Southern Mauritanian Sub Basin
Tortue-1 WD = 2668m TD= 4630m
• 150m gross hydrocarbon bearing interval in the Upper Cenomanian
• 160m gross interval with 3 distinct MULTI-Darcy reservoirs in Lower Cenomanian
• Other plays deeper in the Cretaceous are also expected
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Line Bend
CM-7
E S W
Faulted
Blocks
Updip
closures
Albian slope fan
sand channels
NWAAM - Casamance Sub Basin (AGC)
Top Syn-rift
Sea Bed
Senonian Unc.
Top Albian
Top Aptian
Top Jurassic
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Syn-Rift
Sandstones?
NWAAM - Northern Sub Basin (Offshore The Gambia)
1.8 seconds (TWT)
3.7 seconds (TWT)
FAN-1 Analogue
SNE-1 Analogue
Top Syn-rift
Sea Bed
Senonian Unc.
Top Albian
Top Jurassic
Top Aptian
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Image credit: Africa Petroleum Natural Resources Forum, April 2015
Lamia
Acacia
Rosewood
Sami Paprika
Nema
Mahogany
Alhamdulilah
Albian Shelf Edge
Albian-Santonian Deepwater play
10 km
NWAAM – The Gambia 3D
TGS also have a multi-client 3D survey offshore The Gambia,
2,500 sq. km acquired in 2011
SNE-1 Analogue FAN-1 Analogue
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There are three main petroleum systems present in the MSGBC basin:
• A post-rift sequence:
• Source - proven Aptian / Albian / Turonian;
• Reservoirs - Upper Cretaceous / Tertiary clastic rocks and Jurassic
carbonates;
• Seals - Upper Cretaceous/Tertiary marine shales or allochthonous salt.
• A pre-salt sequence:
• Source rocks - Triassic lacustrine;
• Reservoirs - Triassic syn-rift clastic rocks and/or Jurassic early post-
rift limestones;
• Seals - interbedded shales or salt.
• A pre-rift Silurian/Devonian level:
• proven onshore and probably extending offshore in the shallow shelf
area of Guinea Conakry.
Summary - Prospectivity
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Basin and Sub-basin evolution and architecture is controlled by pre-
existent basement geometry, syn-rift faults, transform movements and salt
tectonics.
The numerous discoveries in the Basin prove the existence of working
petroleum systems along the North West African Passive Margin and
FAN-1 and SNE-1 prove these systems can be commercial.
Potential DHIs such as bright spot and gas related features have been
highlighted.
Conclusions
The complex structural evolution has led to the formation of numerous
structural and stratigraphic traps identified across the study area.
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©2015 TGS-NOPEC Geophysical Company ASA. All rights reserved.
Acknowledgments
TGS for Interpretation and modelling work:
Dario Chisari, Peter Conn, Ian Deighton, Roel Dirkx, Jennifer Halliday, Cian O’Reilly,
and Erika Tiboucha.
External references: African Petroleum (interpretation of TGS 3D) =
http://www.africanpetroleum.com.au/sites/default/files/u147/AP_NaturalResourcesForum_24Apr2015.p
df Last accessed 26th May 2015
Cairn Energy (FAN-1 and SNE-1 geoseismic and pressure curve data) = http://files.the-
group.net/library/cairnenergy/news_presentation/CapitalMarketsDay11MayPresentation.pdf Last
accesed 26th May 2015
FAR Limited (3D Interpretation of SNE-1 and FAN-1) = http://www.far.com.au/wp-
content/uploads/2015/04/20150413-Investor-presentation.pdf
Grant, C. et al. 2013. Hunting for deepwater subtle traps, from Geology to Technology. The 5th Biennial
Petroleum Geology Conference. Bergen, Norway. March 2013.
Thank you
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Thank you
©2015 TGS-NOPEC Geophysical Company ASA. All rights reserved.
Ben Sayers
+44 208 339 4239