Structural geology
Faults and the implications on fluid flow
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• Intro
– What is structural geology?
– Structural geological data
• Structural geology on Gullfaks
– Regional and field scale
• Faults and how they affect the fluid flow in Gullfaks H1 segment
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STRUCTURAL GEOLOGY
Treats (deformation-) structures in the earths crust and how they
are formed.
For Gullfaks these structures are mainly faults
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FAULTS
A surface, or more commonly, a narrow zone along which one of the sides
has been displace past the other side.
Normal
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Revers
Sidelengs
Databasis for structural interpretation
• Seismic data
– Structural processed cubes
– Offset-cubes
– 4D seismic
• Data from more than 200 wells
– Cores (more than 8 km)
– Detailed logs
– Production data
– Pressure data
• Field analogs (Utah)
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200 m
500 m
No info regarding:
Sub-seismic faults
Fault zone
Fault seal
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Field analogs (Utah)
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Structural geology on Gullfaks – regional scale
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Structural development on Gullfaks - keywords
• Two regional rifting periods:
– (Perm)-Triassic
– Middle Jurassic – Early Cretaceous
• Internally on Gullfaks mainly as a result of late Jurassic-early Cretaceous deformation
– Regional thickness variations on the Brent-Group indicates fault development started
in middle Jurassic
• Core studies show that Brent was poorly consolidated (not deep buried) at the time of
deformation
– This has implications on what kind of structures develop
• Brent (middle Jurassic) was deposited in pre-tectonic time
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Structural geology in the
Tampen area
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Structural geology on Gullfaks – field scale
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Strukturgeologi
Domino system
• Faults: 20-30º dip towards east
• Fault geometry is more complex in
Brent than Statfjord
• Layering: ca. 15 degrees towards
west
• Internal deformation
Accomodation
• Mest complex area on Gullfaks
regarding sctructures
Cook (Dunlin)
Horst complex
• Faults: 60-70º dip towards west
• Sub-horisontal layering
• Less internal deformation
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Gullfaks South
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Data collection at different scales
Variation of resolution
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Coredata
(9 m throw)
34/10-A-15
34/10-B-12
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Faults and the implication on fluid flow
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Juxtaposition without seal
Juxtaposition with seal (clay smear)
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Models/seismic interpretaion
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Real?
Thank you
Presentation title
Presenters name
Presenters title
E-mail address, tel: +00 00 00 00
www.statoil.com
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