Global Deepwater Fold Blet Passive vs Active Shell
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Transcript of Global Deepwater Fold Blet Passive vs Active Shell
Global Overview of Tertiary Deepwater Foldbelts :Passive vs. Active Margin Systemsby Scott Sumner, Ciaran O’Byrne, Gary S. Steffens, Robin Hamilton, and Tim FarnhamShell International E&PMarch 8, 2006
Acknowledgements:
Dave Steele, Mike Bourque, Rod Nourse, John Karlo, Mark Rowan, Frank Peele, JohnStainforth, Mike Lentini, Scot Fraser, Larry Garmezy, Daniel Truempy, Dave Stewart, SveinAase, Guy Loftus, Allan Scardina,, Mark Depuck, Carlos Pirmez, Brad Prather, Mike Mahaffie, Peter Mullin, Aly Brandenburg, Eric Bartsch, Tim Chilsom, Gary Ingram, Jeff Lobao, Jim Booth,, Peter Tauvers, Fred Diegal, Brad Robison, Franz Kessler
Frogtech Consultants: Jon Teasdale, Peter Smith
New Zealand Petroleum Conference 2006: Putting energy into exploration
• Distribution, primary and secondary controls
• Examples:- Nigeria- Northwest Gulf of Mexico- Northwest Borneo
• Summary
OutlineOutline
Passive and Active Margin Deepwater FoldbeltsPassive and Active Margin Deepwater Foldbelts
Shelf Edge
Modified after Doust and Omstala (1989), Haan, (1994)
Continental CrustOceanic Crust
Nigeria
NW Borneo
Dangerous GroundsSouth China Seakm
0
4
8
? ? KU - Pg
NW SE
? 100 kmContinental
Crust
Mobilized Shale
Inversions/ FoldsFold/ thrust belt
Fold/ thrust belt
Rajang Basement
Growth Faulting
10 km
100 km
Mod. after Letouzey and Sage(1988)
Passive Margin
Active Margin
Updip extension and loading balanced by downdip contraction and emplacement of mobil substrate.
Unbalanced system with contraction throughout slope and shelf. May have “thin-skinned linked system” superimposed.
“Linked System”
Deepwater Tertiary Foldbelts
Passive Margin salt-based
? ?
Passive Margin shale-basedActive Margin shale-based
~6 BBOE Discovered in 4 basins ~170 MBOE mean field size (29 Discoveries)Data as of early 2004
Tectonic Settings of Deepwater FoldbeltsTectonic Settings of Deepwater Foldbelts
Foldbelt
km
5
0
Mod. after Bergman et al. (1996)
W km
5
0
10Offshore Nigeria
After Speed, 1990; Bouysee and Westercamp, 1988
Oceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Modified after Peel et al., (1995)
From Babonneau et al. (2002)
10 km
100 km
km
SaltPassive Margin
Mod. after Letouzey and Sage(1988)
Active Margin
OceanicCrust
E
NESW
FoldbeltNigeria
West Sulawesi
BarbadosW
SENW
EWAngola
Uplift
Foldbelt
Foldbelt
~5.3 BBOE Discovered ~170 MBOE mean field size
Salt-Based
Shale-Based
CollisionalForeland
Subduction Prism
Salt-Based
CollisionalForelandNW Gulf of Mexico
? ? ?KU - Pg?
Shelf Edge
? ? ?KU - Pg?
Shelf EdgeNW Borneo SE
FoldbeltNW
Mobilized Salt
Mod. after Peel et al.(1990)
Foldbelt
ContinentalCrust
S N
Passive and Active Margin Deepwater Foldbelt Distribution
Salt Canopy
NW G.O.M.
Salt
Nigeria
ShaleNW
BorneoAngolaSalt
Fold, thrust, reverse fault
Shelf-edgeExtent of Linked system
100 Miles100 km
Passive Margin
Active Margin
Accretionary Prism
Barbados
West Sulawesi
CollisionalForeland
CollisionalForeland
NW Borneo
Secondary controls on structural styles of Deepwater Foldbelts
Mobile substrate thickness- thicker forms detachment “buckle” folds- thinner forms thrust faulted folds
From Stewart (1999)
thick substrate
thin substrate
Thick lower-strength substrate (salt)
Lower Congo Basin
Buckle folds
(from Rowan et al., 2004)
Mobile substrate/detachment strength- weaker forms detachment “buckle” folds- stronger forms thrust-faulted and duplexed folds
Thin higher-strength substrate (shale)
(from Costa and Vendeville, 2002)
Thick lower-strength substrate (salt)
Thin higher-strength substrate (shale)
Para-Maranhao Basin-
Imbricated thrusts
0 100Kilometers0 1000 100
Kilometers
Strike-length of fold axis
Deepwater Foldbelt Structural Metrics (n=25)average fold strike length of salt-based passive margin systems
is ~ half that of shale-based passive and active margin systems
Ave Fold Strike Length vs FB Type
0102030405060708090
100
Fold
Str
ike
Leng
th (k
m)
Passive / Salt
Passive / Shale
Active / Shale
17 km. ave.
37 km. ave.
49 km. ave.
Ave Fold Strike Length vs FB Type
0102030405060708090
100
Fold
Str
ike
Leng
th (k
m)
Passive / Salt
Passive / Shale
Active / Shale
17 km. ave.
37 km. ave.
49 km. ave.
Passive/ Salt Passive/ Shale Active/ Shale
883 msecs.twt ave. 755 msecs. twt ave.1000 msecs.twt ave.
Passive/ Salt Passive/ Shale Active/ Shale
10.3 km. ave 11.25 km. ave 11.7 km. ave
Passive/ Salt Passive/ Shale Active/ Shale
10.3 km. ave 11.25 km. ave 11.7 km. ave
Amplitude
wavelength
average fold amplitude and dip wavelengths are similar
NW Borneo seafloor
Illustrations of Structural Play Groups with Mobile Substratum (Salt or Clay)Regional Seismic Lines from 5 Deep Water Basins
P.R. Mullin/H.M. BürgisserDecember 2001
Relative Scales and Positions of Deepwater Foldbelts
NEFold/ Thrust belt
Shelf-edgeToe-of-slope
* Seismic courtesy of Mabon Ltd.
0
5
TWTSecs.
25 KM
Active Margin
Offshore NigeriaPassive Margin Shale-based
SW
SENW
Fold/ Thrust belt
* Mod. From Ingram et al. (2004)
NW BorneoNW SE
Duplex?
Duplexes?
Source rockbearing interval
Gas-prone(Type III)Oil-prone(Type I-II)
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Legend
Source rockbearing intervalSource rockbearing interval
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
LegendDeep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Legend0
50
100
150
200
Ma0
50
100
150
200
Ma NW G.O.M. Nigeria
PerdidoMiss. Fan
?
?
Salt-based Shale-basedAngolaSalt-based
Passive Margin Active MarginStratigraphic Megasequences in Deepwater Foldbelts
D
D
D
NW Borneo
Lower slope?
?
Foreland Shale-based
W. Sulawesi
?
Foreland Shale-based
DD
Foldbelt Deformation
Decollement
Subduction Prism Shale-basedBarbados
D
D
Reservoir Distribution in Deepwater FoldbeltsPassive Margin
Reservoirs are more predictable in passive margin settings than in active margin settings
Wide slopes with low gradients (1- 2o)
Folds are load-driven and occur at toe-of-slope
Pre-kinematic reservoirs are often toe-of slope unconfined fan systems
Active Margin
Narrow slopes with high gradients (2– 4o+)
Folds driven by extra-basinal forces occuring throughout slope and shelf
Pre-kinematic reservoirs depend on slope setting prior to deformation
Shortening
Toe of slope
Shelf edgePre-kinematic
(if present!)
Syn-kinematicFolding
TimeTime Toe of slope
Shelf edge
Progradation
Pre-kinematic
Syn-kinematic
Folding
Source rockbearing interval
Gas-prone(Type III)Oil-prone(Type I-II)
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Legend
Source rockbearing intervalSource rockbearing interval
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
LegendDeep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Legend0
50
100
150
200
Ma0
50
100
150
200
Ma NW G.O.M. Nigeria
PerdidoMiss. Fan
?
?
Salt-based Shale-basedAngolaSalt-based
Passive Margin Active Margin
Source Rocks and Hydrocarbons in Deepwater Foldbelts
D
D
D
NW Borneo
Lower slope?
?
Foreland Shale-based
W. Sulawesi
?
Foreland Shale-based
DD
Foldbelt Deformation
Decollement
Subduction Prism Shale-basedBarbados
D
D
Proven/Inferred HC Mix vs FB Type
0
1
2
3
4
5
6
7
8
Passive / Salt Passive / Shale Active / Shale
# of
FBs
Oil MixGas
HC Mix More GasMore Oil
? ? ?KU - Pg?
Shelf Edge
Thermal Maturity and Heat Flow in Deepwater FoldbeltsThermal Maturity and Heat Flow in Deepwater Foldbelts
NW Borneo
Foldbeltkm
5
0
Mod. after Bergman et al. (1996)
W km
5
0
10Offshore Nigeria
After Speed, 1990; Bouysee and Westercamp, 1988
Oceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Modified after Peel et al., (1995)
From Babonneau et al. (2002)
10 km
100 km
SE
Passive Margin
Mod. after Letouzey and Sage(1988)
Active Margin
OceanicCrust
E
FoldbeltNW
NESW Foldbelt NigeriaWest Sulawesi
BarbadosW
SENW
EW AngolaFoldbelt
km
Foldbelt
-
3540 25
35
Thermal maturity & Heat Flow (mw/m2)
40-60 40->60
50- 60
50
45
Modelled
NGDC
ModelledNGDC
Henry (2000)
40-60 3540->60 Analogy
5035
NW Gulf of Mexico
Mobilized Salt
Mod. after Peel et al.(1990)
Foldbelt
ContinentalCrust
S N
Hydrocarbon Migration and Entrapment in Deepwater Foldbelts
sea floor
Filled Traps
Wet Traps
maturitysource
rock
Complex, high relief structures inhibit long distance lateral HC migration within foldbelts
HC migration is generally short distance from nearby “kitchens”
Vertical HC migration pathways can be complicated by position of source rocks relative to detachments
Continental CrustContinental CrustContinental Crust
Oceanic CrustMobilized ShaleOceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Salt
Modified after Peel et al., (1995)
FoldbeltNS
NESW
Passive Margin Salt-Based
Passive Margin Shale-BasedFoldbelt Nigeria
NW Gulf of Mexico
Mod. after Peel et al.(1990)
Shelf Edge
? ? ?KU - Pg?
NW Borneo SE
Mod. after Letouzey and Sage(1988)
FoldbeltNWActive Margin Foreland
10 km
100 km
10 km
100 km
X-section scale
RajangBasement
Salt Canopy
NW G.O.M.
Nigeria
100 km
Fold, thrust, reverse fault
Shelf-edge
Linked system extent
Map LegendNW BorneoNW Borneo
Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo
Mobilized Salt
Foldbelt
ContinentalCrust
• Distribution, primary and secondary controls
• Examples:- Nigeria- Northwest Gulf of Mexico- Northwest Borneo
• Summary
OutlineOutline
Continental CrustContinental CrustContinental Crust
Oceanic CrustMobilized ShaleOceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Salt
Modified after Peel et al., (1995)
FoldbeltNS
NESW
Passive Margin Salt-Based
Passive Margin Shale-BasedFoldbelt Nigeria
NW Gulf of Mexico
Mod. after Peel et al.(1990)
Shelf Edge
? ? ?KU - Pg?
NW Borneo SE
Mod. after Letouzey and Sage(1988)
FoldbeltNWActive Margin Foreland
10 km
100 km
10 km
100 km
X-section scale
RajangBasement
Salt Canopy
NW G.O.M.
Nigeria
100 km
Fold, thrust, reverse fault
Shelf-edge
Linked system extent
Map LegendNW BorneoNW Borneo
Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo
Mobilized Salt
Foldbelt
ContinentalCrust
•Passive margin shale-based fold/ thrust belts
•Positioned on lower slope and toe-of-slope
•Miocene to Recent age
Nigeria Deepwater Fold/ Thrust Belts
Middle Miocene Depth Structure
Fold/ Thrust Belts
100 km
Offshore Nigeria Seafloor Structure
TWT(msec)
N
Fold/ Thrust belt
50 km
Seismic Data courtesy of Mabon Ltd.
AA’0
5
TWT(sec)
NE
A
A’
SW
Duplex?
3 secs. twt
5 km
AA’
Depth Structure Miocene
A
A’
5 km
Dominated by basinward-vergent thrusted folds…
Depth Structure Map
Nigeria Deepwater Fold/ Thrust Belts
B
B’ 5 km
5 km
BB’
… but complex back thrusts occur locally
Depth Structure Map
Back Thrusts
Seismic courtesy of Mabon Ltd.
Nigeria Deepwater Fold/ Thrust BeltsBasinward-vergent thrusted folds become younger and more imbricated downdip… caused by basinward increase in strength of decollement (decrease in fluid pressures)?
Mod. From Rowan et al. (2004)
Some updip folds may be underlain by duplex structures localized by decollement step-downs
Offshore Nigeria Drainage AnalysisOffshore Nigeria Drainage Analysis
From Steffens et al. (2003)
Long dip-oriented drainage paths bypass upper sloe, many making it to the toe-of-slope
Ponded Accommodation
Only small amounts of pondedaccommodation between actively growing folds
Nigeria Deepwater Foldbelt Petroleum Systems
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
Tx
0
50
100
150
Ma Nigeria
??
Main source rocksPg –K marine clastics,oil and gas prone
Basinward decrease in heat flow and thermal maturity
Mod. after Doust and Omstala (1989)
Oceanic Crust
Mobilized Shale
Modified after Peel et al., (1995)
10
100 km
NESWkm0
ContinentalCrust
Heat Flow and Thermal Maturity
Top Oil window
Ikija
Main reservoirs
• Distribution, primary and secondary controls
• Examples:- Nigeria- Northwest Gulf of Mexico- Northwest Borneo
• Summary
OutlineOutline
Oceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Salt
Modified after Peel et al., (1995)
FoldbeltNS
NESW
Passive Margin Salt-Based
Passive Margin Shale-BasedFoldbelt Nigeria
NW Gulf of Mexico
Mod. after Peel et al.(1990)
Shelf Edge
? ? ?KU - Pg?
NW Borneo SE
Mod. after Letouzey and Sage(1988)
FoldbeltNWActive Margin Foreland
10 km
100 km
Salt Canopy
NW G.O.M.
Nigeria
X-section scale
100 km
Fold, thrust, reverse fault
Shelf-edge
Linked system extent
Map Legend
RajangBasement
NW Borneo
Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo
Mobilized Salt
Foldbelt
ContinentalCrust
NW Gulf of Mexico Deepwater Foldbelts
Passive margin salt-based foldbelts Positioned on lower slope/ toe-of-slopePg. to Late Miocene age
100 Miles
MSF Foldbelt
Perdido Foldbelt
Modified from Peel et al. (1995)
B B’A A’
B’A’
B
A
C
C’ C C’
Structural Styles in the G.O.M. Deepwater Foldbelts
10 k
m
50 km
Modified after Peel et al., 1995
Mississippi Fan Foldbelt
NW GOM Deepwater Foldbelts
100 Km
PerdidoFoldbelt
AB
C
D
SN K2 Mad Dog
Pleist.Pliocene
MiocenePg.
KJ
Line B N SLine A
W ETridentBaha
Eo.-Pc.
Line D N S
Eo.-Pc.
Line C
KJ
St MaloMiocene
Unconfined Fan Deposition, Toe of Slope, Atwater ValleyPre-Kinematic unconfined fan reservoir analogue for Mississippi Fan Foldbelt
Channelized debris lobe Ponded sheets Channel+margin Channelized sheetsA B
Overlapping and coalescing unconfined abyssal plain fans incorporated into prograding foldbelt
A
B
Mississippi Canyon & Atwater Valley, Upper Miocene (5.5 ma Messinian event)
Mississippi Canyon & Atwater ValleyUpper Miocene (5.5. ma Messinian event)
A
NW Gulf of Mexico Deepwater Foldbelt Petroleum Systems
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
LegendNW G.O.M.
Tx. La.
0
50
100
150
200
Ma
?
Main source rocksUJ (Tith.) – UK (C-T)Type I/II Marine oil-prone
100 Miles100 Miles
MSF Foldbelt
NW G.O.M. Seafloor and Deepwater Source Type from Seepage and Oils
(modified from Cole et al, 1999)
Carbonate Province
Marl and Clastic Province
Clastic Province
Perdido Foldbelt
General basinward decay in heat flow and thermal maturity for source rocks
Salt locally modifies regional thermal maturityContinental
Crust
Mobilized Salt
Foldbelt
NS NW Gulf of Mexico
Mod. after Peel et al.(1995)
10
100 km
0
Heat Flow and Thermal Maturity
Top oil window
Multiple Source Rocks
Main reservoirs
Mod. From Cole et al. 1999)
NW GOM Deepwater Foldbelts
100 Km
Mississippi FanFoldbelt
PerdidoFoldbelt
NW GOM Deepwater Foldbelts
100 Km
NW GOM Deepwater Foldbelts
100 Km100 Km
Mississippi FanFoldbelt
PerdidoFoldbelt
Perdido Foldbelt Oil Discoveries• large Oligocene-age detachment folds• Paleocene deepwater sand reservoirs
Mod. From Trudgill et al. (1999)
A
B
Oil discoveries on trend in buried “non-apex” anticlinal structures
Salt
A B
Miss. Fan Foldbelt Oil Discoveries• large Late Miocene subsalt detachment folds• Early Miocene deepwater sand reservoirs
K2 Mad Dog
Mod. From Grando and McClay (2004)
• Distribution, primary and secondary controls
• Examples:- Nigeria- Northwest Gulf of Mexico- Northwest Borneo
• Summary
OutlineOutline
Oceanic CrustMobilized Shale
Mod. after Doust and Omstala (1989)
Salt
Modified after Peel et al., (1995)
FoldbeltNS
NESW
Passive Margin Salt-Based
Passive Margin Shale-BasedFoldbelt Nigeria
NW Gulf of Mexico
Mod. after Peel et al.(1990)
Shelf Edge
? ? ?KU - Pg?
NW Borneo SE
Mod. after Letouzey and Sage(1988)
FoldbeltNWActive Margin Foreland
10 km
100 km
Salt Canopy
NW G.O.M.
Nigeria
X-section scale
100 km
Fold, thrust, reverse fault
Shelf-edge
Linked system extent
Map Legend
RajangBasement
NW Borneo
Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo Deepwater Foldbelts of NW Gulf of Mexico, Nigeria, and NW Borneo
Mobilized Salt
Foldbelt
ContinentalCrust
NW Borneo Active Margin Deepwater Foldbelt
0 100Kilometers
GPS measurements indicate that NW Borneo is a tectonically active setting with ~4 cm / yr NW-SE convergence (Rangin et al, 1999)
South China Sea
Sulu Sea
Celebes Sea
Borneo
400 km
Brunei
Bathymetry Map
South China Sea
Sulu Sea
Celebes Sea
Borneo
400 km
Brunei
Bathymetry Map
NW Borneo Seafloor~4 cm / yr convergence
NW Borneo Deepwater Foldbelt
Dangerous GroundsSouth China Seakm
0
4
8
? ? KU - Pg
NW SE
? 100 km100 kmContinental
Crust
Inversions/ FoldsFold/ thrust belt
Rajang Basement
Mod. after Letouzey and Sage(1988)
Stepped Slope Profile
100 km
~4cm / yr of convergenceNW Borneo Seafloor
Active margin shale-based foldbelts Miocene – Recent age
Unbalanced structural system with coeval contractional features throughout basin
BB
BB’’
Borneo
NW Borneo Regional Crustal Framework
Dangerous Grounds - Reed Banks Terrane
Mantle (ρ=3.2g/cm3)
RajangTerrane Meratus Terrane
Rajang-CrockerFold-Thrust Belt
Lower Crust (ρ=2.9g/cm3)
Upper Crust (ρ=2.7g/cm3)
Rajang Group(ρ=2.5g/cm3)
Oceanic Crust (ρ=2.9g/cm3)
Sediment (ρ=2.3g/cm3)
Water (ρ=1.05g/cm3)
Counter-regionalnormal fault
MeratusTerrane
Measured Gravity
Modelled Gravity
No gravity data
200km
0
10
20
30
40
0
10
20
30
40
0
500
1000
-500
0
500
1000
-500
B B’NW SE
SubductedProto-South China Sea
B’B’ South China Sea
Modified from Frogtech (formerly SRK) Consultants
NW Borneo
Dangerous GroundsSouth China Seakm
0
4
8
? ? KU - Pg
NW SE
? 100 kmContinental
Crust
Inversions/ FoldsThrust-Foldbelt
Rajang Basement
Mod. after Letouzey and Sage(1988)
Gravity interpretations suggest that parts of the NW Borneo slope are underpinned by high density outliers of Rajang Basement
NW Borneo Middle Miocene – Recent Kinematic Model
Modified from Ingram et al. (2004)
• NW moving basement allochthondriven by extra-basinal forces
• Allocthon bounded by major shears
• Folds are cored by allochthoninboard and detached outboard
0
8
sectwt
10 km
SENW
Rajang Rajang basementbasementD.GroundsD.Grounds--Reed Banks Reed Banks
TerraneTerrane BasementBasement
SABAH TROUGH
DETACHED FOLD & THRUST BELT
21.8 Ma21.8 Ma
OUTBOARD ALLOCHTHON
Complex trap history influenced by basement allochthon & shearing
Modified from Ingram et al. (2004)
Ridge
2.5 km
Brunei Slope Canyon
Effect of subtle topographic features on reservoir distribution
NW Borneo Deepwater Foldbelt ReservoirsHigh gradient (2 – 4 ) stepped profileHealed slope accommodation with significant bypassChannelized reservoirs common
NW Borneo
Lower slope?
?
Active Shale
Tx
0
50
100
Ma
Deep marine clastic Deep marine shales / carbonatesShallow Marine carbonatesEvaporites
Synrift
Source rockbearing interval
Legend
50 90
mW/m2
ModelledHeat Flow
*
Foldbelt
Main source rocks are Miocene Terrestrial gas and oil-prone
NW Borneo Deepwater Foldbelt Petroleum Systems
General basinward increase in heat flow and thermal maturity
Mod. after Letouzey and Sage(1988)
NW Borneo
8100 km
? ? ?KU - Pg?
SE
FoldbeltNW
RajangBasement
kmo
Top oil window
Continental Crust
?
KikehGumusut
Heat Flow and Thermal Maturity
Mod. after Letouzey and Sage(1988)
NW Borneo
8100 km
? ? ?KU - Pg?
SE
FoldbeltNW
RajangBasement
kmo
Top oil window
Continental Crust
?
KikehGumusut
Heat Flow and Thermal Maturity
• Distribution, primary and secondary controls
• Examples:- Nigeria- Northwest Gulf of Mexico- Northwest Borneo
• Summary
OutlineOutline
Global Overview of Tertiary Deepwater FoldbeltsSummary of Structure
• Passive margin DW foldbelts are driven by updip loading and extension (“linked system”)
• Active margin foldbelts are driven by extra-basinal plate-tectonic events often forming independent of loading in the basin
• Folding/ thrusting commonly occurs throughout basin on active margins and is confined to the lower slope/ toe-of slope on passive margins
• DW foldbelt structural styles are related to “secondary controls” such as presence / type of mobile substrate, rheology of overburden, and amount of shortening
Global Overview of Tertiary Deepwater FoldbeltsSummary of Reservoir
Passive margin reservoirs are usually closely associated with load-driven structural deformation (“linked systems”)
Active margins have higher slope gradients than passive margins resulting in increased bypass (“stepped profiles”)
Due to extra-basinal tectonism, active margin reservoir distribution can be independent of intra-basin structural history
Global Overview of Tertiary Deepwater FoldbeltsSummary of Petroleum Systems
Heat flow and thermal maturity generally decreases basinward on passive margins but can be highly variable on active margins
Active margins are more ephemeral systems with fewer potential source rocks than passive margins
Active margin source rocks are often more terrestrial and gas prone, while passive margin source rocks are often more marine and oil-prone
Passive margin DW foldbelts are generally more oil-prone than active margin foldbelts
Global Overview of Tertiary Deepwater Foldbelts
“Grand” Summary
• Differences in deepwater foldbelts may have huge implications for petroleum systems and prospectivity
• But differences may be systematic and predictable
Large untested scope still remains!
Thanks!