Rifting Systems and its significance for hydrocarbon exploration in the Netherlands Utrecht, 5-6-2008
Post-rift fault reactivation in the Netherlands
implications for exploration and production
Fred Beekman
Jan-Diederik van Wees Sierd Cloetingh
Post-rift fault reactivation in the Netherlands
implications for exploration and production
Fred Beekman
Jan-Diederik van Wees
Sierd Cloetingh
Post-rift fault reactivation in the Netherlands 2
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 up
10W
0E 10E 20E
30E
40E 40N
50N 60N
70N
Contents
reference
Strength evolution and seismicity of European rift systems
Fault reactivation in the Netherlands
Roer 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 Netherlands
Roer 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 Netherlands 4
European Cenozoic Rift System (ECRIS)
Lithosphere extension and rift basin formation
Lithosphere
(Sub)basin
Reservoir
Coupled deformation at different spatial scales
Coupled deformation at different spatial scales
Post-rift fault reactivation in the Netherlands 6
3-D rheological strength models
Cloetingh et al., 2005
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 cooling post-rift cooling syn-rift
stretching & heating syn-rift stretching & heating
Post-rift fault reactivation in the Netherlands 8
Present-day strength of the European lithosphere
Maps of integrated rheological strength Maps of integrated rheological strength Entire lithosphere
Entire lithosphere Crust only Crust only
Cloetingh et al., 2005
Present-day strength of ECRIS rift systems
2-D profiles extracted from the 3-D strength cubes 2-D profiles extracted from the 3-D strength cubes
Cloetingh et al., 2005
Post-rift fault reactivation in the Netherlands 10
Correlation strong/weak zones with seismicity
Increased seismicity in ECRIS Increased seismicity in ECRIS
Cloetingh et al., 2006 World Stress Map project
Intraplate stress field
Intraplate stress field
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)
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 Netherlands 14
0 5 10 5
SW ROER VALLEY GRABEN NW
SE-NETHERLANDS
0 20 40 60 80 100 200 600
Dirkzwager et al., 2001
Lithosphere memory of faults
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)
-40 0
10
VERTICAL DISPLACEMENTS (M)
Dirkzwager et al., 2001
Finite element models assessing the role of fault friction are constrained by geometry of the graben system
Finite element models assessing the role of fault friction are constrained
by geometry of the graben system
Post-rift fault reactivation in the Netherlands 16
Likelihood of fault reactivation can be quantified by e.g. a slip tendency analysis
Likelihood 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)
Strike-slip faulting stress regime Normal faulting stress regime
Worum et al. (2004)
Fault reactivation potential of the RVRS
Post-rift fault reactivation in the Netherlands 18
erosion reactivated faults
West-Netherlands Basin
Basin inversion: reactivation of the pre-existing weak fault fabric and substantial regional uplift and erosion
Basin inversion: reactivation of the pre-existing weak fault fabric and substantial regional uplift and erosion
Worum and Van Wees, submitted
After Ellis et al., 1999
Soultz
Implications of fault reactivation for exploration
Migration pathways
Barriers
Seal capacity
Migration pathways
Barriers
Seal 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 Netherlands 20
Some faults show more fault slip than others
Reservoir Seal
Overburden Growth sequence
Implications for hydrocarbon exploration
Reactivated faults can disrupt reservoir seals -> (partial) loss of hydrocarbons
Reactivated faults can disrupt reservoir seals -> (partial) loss of hydrocarbons
N S
2000m
BPLI TM1
TM3
TE
KA
JO KC
N S
BPLI TM1
TM3
TE
KA JO KC
2000m
TWT
Juxtaposition Seal SGR >60%
Both traps lost oil; both traps are bounded by reactivated “large strain” faults that were active at the seabed
Both traps lost oil; both traps are bounded by reactivated “large strain” faults that were active at the seabed
Juxtaposition Seal SGR >60%
Example case
Implications for hydrocarbon exploration
Post-rift fault reactivation in the Netherlands 22
Dynamic Fault Seal project
Integrated Field Studies
Numerical Modelling
Qf Qm
Scaled Physical Modelling
σ
3σ
1Natural versus induced seismicity in the Netherlands
Cloetingh et al., 2006 Van Eck et al., 2006
Post-rift fault reactivation in the Netherlands 24
Induced seismicity in the NE Netherlands
The induced seismicity also occurs predominantly on pre-existing faults The induced seismicity also occurs predominantly on pre-existing faults
Van Eck et al., 2006
Production induced seismicity
… which may induce fault reactivation.
Local effects:
change in fault permeability
change in structural fabric
stress reorganization
… which may induce fault reactivation.
Local effects:
change in fault permeability
change in structural fabric
stress reorganization
Relative shear displacements along Fault 1
0 50 100 150 200 250 300 350 400
0.00 0.10 0.20 0.30 0.40 0.50
Relative shear displacement [m]
Relative distance along the fault [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
Post-rift fault reactivation in the Netherlands 26
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
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 Netherlands 28
Quantification of fault reactivation potential
(Buchmann, 2008)
Dilation tendency Slip tendency
Prediction of surface uplift & subsidence
(Buchmann, 2008)
Surface displacements Vertical gradient of surface displacement
Post-rift fault reactivation in the Netherlands 30
Verification and calibration
Van Eijs et al., 2006
Verification with independent seismic hazard studies
Verification with independent seismic hazard studies
Calibration with measured induced surface subsidence
Calibration with measured induced
surface subsidence
High resolution 3D finite element modelling
Local scale modelling of reservoir depletion induced fault reactivation and subsidence Local 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 Netherlands 32
