Structural geology Faults and the implications on fluid

Structural geology Faults and the implications on fluid flow 1 - Classification: Internal 2011 -02 -10

• 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 H 1 segment 2 - Classification: Internal 2011 -02 -10

STRUCTURAL GEOLOGY Treats (deformation-) structures in the earths crust and how they are formed. For Gullfaks these structures are mainly faults 3 - Classification: Internal 2011 -02 -10

FAULTS A surface, or more commonly, a narrow zone along which one of the sides has been displace past the other side. Normal 4 - Classification: Internal 2011 -02 -10 Revers Sidelengs

Databasis for structural interpretation • Seismic data – Structural processed cubes – Offset-cubes – 4 D seismic • Data from more than 200 wells – Cores (more than 8 km) – Detailed logs – Production data – Pressure data • Field analogs (Utah) 5 - Classification: Internal 2011 -02 -10

200 m 500 m ss /Ne ch Ta nno a R ve/ ke Eti Dra en nds u Am ok/ Co rd tfjo a t S rt rbe No info regarding: Sub-seismic faults Fault zone Fault seal 6 - Classification: Internal 2011 -02 -10

Field analogs (Utah) 7 - Classification: Internal 2011 -02 -10

Structural geology on Gullfaks – regional scale 8 - Classification: Internal 2011 -02 -10

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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 10 - Classification: Internal 2011 -02 -10

Structural geology in the Tampen area 11 - Classification: Internal 2011 -02 -10

Structural geology on Gullfaks – field scale 12 - Classification: Internal 2011 -02 -10

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 13 - Classification: Internal 2011 -02 -10

Gullfaks South 14 - Classification: Internal 2011 -02 -10

Data collection at different scales Variation of resolution 15 - Classification: Internal 2011 -02 -10

Coredata (9 m throw) w ro 9 (6 m ) th 34/10 -A-15 34/10 -B-12 16 - Classification: Internal 2011 -02 -10

Faults and the implication on fluid flow 17 - Classification: Internal 2011 -02 -10

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Juxtaposition without seal Juxtaposition with seal (clay smear) 19 - Classification: Internal 2011 -02 -10

Models/seismic interpretaion 20 - Classification: Internal 2011 -02 -10 Real?

Thank you Presentation title Presenters name Presenters title E-mail address, tel: +00 00 www. statoil. com 21 - Classification: Internal 2011 -02 -10