View
8
Download
0
Category
Preview:
Citation preview
Rifting Systems and its significance for hydrocarbon exploration in the NetherlandsUtrecht, 5-6-2008
Post-rift fault reactivation in the Netherlandsimplications for exploration and production
Fred BeekmanJan-Diederik van WeesSierd Cloetingh
Post-rift fault reactivation in the Netherlandsimplications for exploration and production
Fred BeekmanJan-Diederik van WeesSierd Cloetingh
Post-rift fault reactivation in the Netherlands2
TOPO-EUROPE:geo-science of coupled surface and lithosphere & mantle processes of continental Europe and its margins
TOPO-EUROPE:geo-science of coupled surface and lithosphere & mantle processes of continental Europe and its margins
Neotectonic vertical motions and seismicity in Europe
Cloetingh et al., 2007 (GPC)
Earthquakes
Areas going down
Areas going up10W
0E 10E 20E30E
40E
40N
50N
60N
70N
Post-rift fault reactivation in the Netherlands3
Contents
reference
Strength evolution and seismicity of European rift systems
Fault reactivation in the NetherlandsRoer Valley Rift System: seismicity and reactivation potential
West Netherlands Basin inversion
Implications of fault reactivation for exploration
Production induced fault reactivation in the NE Netherlands
Strength evolution and seismicity of European rift systems
Fault reactivation in the NetherlandsRoer Valley Rift System: seismicity and reactivation potential
West Netherlands Basin inversion
Implications of fault reactivation for exploration
Production induced fault reactivation in the NE Netherlands
Post-rift fault reactivation in the Netherlands4
European Cenozoic Rift System (ECRIS)
Post-rift fault reactivation in the Netherlands5
Lithosphere extension and rift basin formation
Lithosphere(Sub)basin
Reservoir
Coupled deformation at different spatial scalesCoupled deformation at different spatial scales
Post-rift fault reactivation in the Netherlands6
3-D rheological strength models
Cloetingh et al., 2005
Post-rift fault reactivation in the Netherlands7
Strength evolution of rift basins
In time the post-rift strength can even exceed the initial pre-rift strength of the lithosphere:
•Young (hot) rifts are weak
•Old (cold) rifts are strong
In time the post-rift strength can even exceed the initial pre-rift strength of the lithosphere:
•Young (hot) rifts are weak
•Old (cold) rifts are strong
syn-rift
post-rift
Ziegler et al., 1998
post-rift coolingpost-rift coolingsyn-rift
stretching & heating
syn-rift
stretching & heating
Post-rift fault reactivation in the Netherlands8
Present-day strength of the European lithosphere
Maps of integrated rheological strengthMaps of integrated rheological strength
Entire lithosphereEntire lithosphere Crust onlyCrust only
Cloetingh et al., 2005
Post-rift fault reactivation in the Netherlands9
Present-day strength of ECRIS rift systems
2-D profiles extracted from the 3-D strength cubes2-D profiles extracted from the 3-D strength cubes
Cloetingh et al., 2005
Post-rift fault reactivation in the Netherlands10
Correlation strong/weak zones with seismicity
Increased seismicity in ECRISIncreased seismicity in ECRIS
Cloetingh et al., 2006 World Stress Map project
Intraplate stress fieldIntraplate stress field
Post-rift fault reactivation in the Netherlands11
Seismicity in the Netherlands
Cloetingh et al. 2005
In the Netherlands also many earthquakes occur on pre-existing fault systems
In the Netherlands also many earthquakes occur on pre-existing fault systems
12
Seismicity and main structural elements
Worum et al. (2004)
Roer Valley Rift System (RVRS)
Post-rift fault reactivation in the Netherlands13
Paleo-seismicity studies in RVRS
Trenching across the Feldbiss fault zone, a border fault of the Roer Valley Graben(SE Netherlands):
250.000 yr old river deposits (left) have been displaced 5 m downwards along the fault
Trenching across the Feldbiss fault zone, a border fault of the Roer Valley Graben(SE Netherlands):
250.000 yr old river deposits (left) have been displaced 5 m downwards along the fault
Houtgast, 2002
Post-rift fault reactivation in the Netherlands14
0510
5
SW ROER VALLEY GRABEN NWSE-NETHERLANDS
0 20 40 60 80 100 200 600
Dirkzwager et al., 2001
Lithosphere memory of faults
Post-rift fault reactivation in the Netherlands15
Modelling of fault reactivation in RVRS
5
VERTICAL DISPLACEMENTS AT VARIOUS DEPTHS (x100)
0km
1km
2km
3km
4km
0km
1km
2km
3km
4km
5
DEFORMED MESH AFTER 200 M EXTENSION(x25)
-40010VERTICAL DISPLACEMENTS (M)
Dirkzwager et al., 2001
Finite element models assessing the role of fault friction are constrained by geometry of the graben systemFinite element models assessing the role of fault friction are constrained by geometry of the graben system
Post-rift fault reactivation in the Netherlands16
Likelihood of fault reactivation can be quantified by e.g. a slip tendency analysisLikelihood of fault reactivation can be quantified by e.g. a slip tendency analysis
Worum et al. (2004)
Potential for fault reactivation
Worum et al. (2004)
Post-rift fault reactivation in the Netherlands17 Worum et al. (2004)
Strike-slip faulting stress regimeNormal faulting stress regime
Worum et al. (2004)
Fault reactivation potential of the RVRS
Post-rift fault reactivation in the Netherlands18
erosionreactivated faults
West-Netherlands Basin
Basin inversion: reactivation of the pre-existing weak fault fabric and substantial regional uplift and erosionBasin inversion: reactivation of the pre-existing weak fault fabric and substantial regional uplift and erosion
Worum and Van Wees, submitted
Post-rift fault reactivation in the Netherlands19
After Ellis et al., 1999
Soultz
Implications of fault reactivation for exploration
Migration pathwaysBarriersSeal capacity
Migration pathwaysBarriersSeal capacity
Change in fault permeability (along fault and across fault) Change in fault permeability (along fault and across fault)
Post-rift fault reactivation in the Netherlands20
Some faults show more fault slip than others
Reservoir
Seal
Overburden
Growthsequence
Implications for hydrocarbon exploration
Reactivated faults can disrupt reservoir seals -> (partial) loss of hydrocarbons Reactivated faults can disrupt reservoir seals -> (partial) loss of hydrocarbons
Post-rift fault reactivation in the Netherlands21
N S
2000m
BPLI
TM1
TM3
TE
KA
JO
KC
N S
BPLI
TM1
TM3
TE
KA
JO
KC
2000m
TWT
Juxtaposition SealSGR >60%
Both traps lost oil; both traps are bounded by reactivated “large strain” faults that were active at the seabedBoth traps lost oil; both traps are bounded by reactivated “large strain” faults that were active at the seabed
Juxtaposition SealSGR >60%
Example case
Implications for hydrocarbon exploration
Post-rift fault reactivation in the Netherlands22
Dynamic Fault Seal project
Integrated Field Studies
Numerical Modelling
Qf
Qm
Scaled Physical Modelling
σ3
σ1
Post-rift fault reactivation in the Netherlands23
Natural versus induced seismicity in the Netherlands
Cloetingh et al., 2006 Van Eck et al., 2006
Post-rift fault reactivation in the Netherlands24
Induced seismicity in the NE Netherlands
The induced seismicity also occurs predominantly on pre-existing faultsThe induced seismicity also occurs predominantly on pre-existing faults
Van Eck et al., 2006
Post-rift fault reactivation in the Netherlands25
Production induced seismicity
… which may induce fault reactivation.
Local effects:change in fault permeabilitychange in structural fabricstress reorganization
… which may induce fault reactivation.
Local effects:change in fault permeabilitychange in structural fabricstress reorganization
Relative shear displacements along Fault 1
050
100150200250300350400
0.00 0.10 0.20 0.30 0.40 0.50
Relative shear displacement [m]
Rela
tive
dist
ance
alo
ng
the
faul
t [m
]
3 years after the start of gas injection 4 yr 5yr 7 yr
Slip on the fault due to CO2 injection = induced micro-seismicity
Changes in pore pressure conditions during HC production (injection/depletion) or CO2 storage induce changes in effective stress, …
Changes in pore pressure conditions during HC production (injection/depletion) or CO2 storage induce changes in effective stress, …
Orlic (2008)
Orlic, 2008
Post-rift fault reactivation in the Netherlands26
Seismo-tectonic fault modelling of NE Netherlands
ISES – TNO project:
reproduce/predict the production induced seismicity in the NE Netherlands
ISES – TNO project:
reproduce/predict the production induced seismicity in the NE Netherlands
1. Build a 3D structural fault model
2. Compute 3D stress distribution
• loading by regional tectonic stress field
• incorporate effects of reservoir depletion
3. Perform slip tendency & fault reactivation analysis on fault planes
4. Verification/calibration with recorded and historical seismicity
• Seismological database KNMI
• LOFAR
1. Build a 3D structural fault model
2. Compute 3D stress distribution
• loading by regional tectonic stress field
• incorporate effects of reservoir depletion
3. Perform slip tendency & fault reactivation analysis on fault planes
4. Verification/calibration with recorded and historical seismicity
• Seismological database KNMI
• LOFAR
Post-rift fault reactivation in the Netherlands27
Construction of 3D structural fault model
From high resolution 3D seismic data …
Top of Upper Rotliegend Group (De Jager & Geluk, 2007)
… to 3D geometry …
…to a full 3D structural fault model.
Michon & Sokoutis, 2005
Buchmann, 2008
Post-rift fault reactivation in the Netherlands28
Quantification of fault reactivation potential
(Buchmann, 2008)
Dilation tendency Slip tendency
Post-rift fault reactivation in the Netherlands29
Prediction of surface uplift & subsidence
(Buchmann, 2008)
Surface displacements Vertical gradient of surface displacement
Post-rift fault reactivation in the Netherlands30
Verification and calibration
Van Eijs et al., 2006
Verification with independent seismic hazard studiesVerification with independent seismic hazard studies
Calibration with measured induced surface subsidenceCalibration with measured induced surface subsidence
Post-rift fault reactivation in the Netherlands31
High resolution 3D finite element modelling
Local scale modelling of reservoir depletion induced fault reactivation and subsidenceLocal scale modelling of reservoir depletion induced fault reactivation and subsidence
Calculated displacements due to gas extraction
Subsidence bowl
Induced seismicity hypocentres
Orlic, 2008
Post-rift fault reactivation in the Netherlands32
Conclusions
European ECRIS rift systems are still rheologically weak structures with increased seismicity
In the Netherlands, earthquakes tend to occur on pre-existing fault planes in the subsurface
Fault slip and dilation tendency analyses can quantify the faultreactivation potential of pre-existing faults, and thus seismic hazard
Fault reactivation may affect hydrocarbon recovery at exploration and production time scales
European ECRIS rift systems are still rheologically weak structures with increased seismicity
In the Netherlands, earthquakes tend to occur on pre-existing fault planes in the subsurface
Fault slip and dilation tendency analyses can quantify the faultreactivation potential of pre-existing faults, and thus seismic hazard
Fault reactivation may affect hydrocarbon recovery at exploration and production time scales
Recommended