Upper Jurassic tectono-stratigraphic concept for King Lear (block 2/4): an old discovery and an eye-opener for Norwegian Central Graben

Transcription

1 Thou shouldst not have been old till thou hadst been wise Upper Jurassic tectono-stratigraphic concept for King Lear (block 2/4): an old discovery and an eye-opener for Norwegian Central Graben Magdalena-Oana Badescu, Statoil Field Development Early Phase Classification: Open Statoil ASA 25 oktober 2016

2 Geological setting- Structural Jurassic isochron TWT 2/4-22S (proj) Hidra High 2/4-23S (proj) Steinbit Terrace Cretaceous Triassic J50 J66 J64 Jurassic J63 Breiflabb Graben Salt PSDM 2012 Triassic geometries Pod/Interpod Decouples/ partially decouples Salt Permian faults Late Jurassic faults Core #2 (1) Tectonic interplay (2) Geometries (3) Sand distribution 2 Classification: Open 25 oktober 2016 Statoil ASA

3 King Lear Salt withdrawal from Interpods Reactive Ddiapirims Fault extension Forced-folding RAFT DECO Geological setting- Stratigraphy Millenium Atlas (2002) seismic BC(U) J66/TET J63/NBT J60 BABY/KIMM Permian Wonham et al., 2014 HPHT conditions hamper the use of J s Not classical Exxon sequence stratigraphy Statoil approach: understand timing and style of the tectonic events that controll Upper Jurassic geometries hence sand distribution inside the stratigraphic packages 3 Classification: Open 25 oktober 2016 Statoil ASA

4 Vertical resolution 50 m Acoustic impedance on shales Thickness and geometry of the shale packages mapped on seismic VpVs vs AI Not possible to distinguish 20 m net sand on seismic FOCUS Seismic tie of the shales Thickness and geometry of shale packages Best Seismic tie 4 Classification: Open 25 oktober 2016 Statoil ASA

5 Structural styles Pod/Interpod (1a) (Triassic)-Salt withdrawal (Kimmeridgian) (1b) Hodgson et al., Thick-skinned faulting (Permian to early Cretaceous) Duffy et al., Salt-fault interaction (Kimmeridgian to Early Cretaceous) Withjack and Callway (2000) 4. Degradational complex Welbon et al, Reactive diapir (Tithonian-early Cretaceous) Vendeville and Jackson, Compression (inversion)- Albian, Stewart et al, /6-6 2/4-23S 2/4-22S 2/ b 5 1a 2 3 SW PSDM 2012 NE 5 Classification: Open 25 oktober 2016 Statoil ASA

6 Structural seismic interpretation- horizons NW SE Zoom in PSDM Triassic thinning towards the salt = Pod/Interpod 2. Basement fault + salt = forced-fold Triassic 3. Subtle thickening towards North in Kimmeridgian- Early Tithonian (J50, J60, J63, J64) Salt 4. Pronounced thickening towards North in Late Tithonian-Early Cretaceous (J66, BCU, Bshetland) near_mid_far_pspro PSDM 2012 PSDM PSDM Classification: Open 25 oktober 2016 Statoil ASA

7 Structural seismic interpretation- master faults 7 Classification: Open 25 oktober 2016 Statoil ASA

8 Structural seismic interpretation- eroded highs 8 Classification: Open 25 oktober 2016 Statoil ASA

9 Migrating depocenters All faults active from Kimmeridgian to Early Cretaceous. What is different: Displacement Style Master faults main responsible for the migration of depocenters Salt and fault interaction (forcedfolding) responsible for the geometries: Wedges Pillows 9 Classification: Open 25 oktober 2016 Statoil ASA

10 Section 1 Hidra High Late Tithonian Early Tithonian Late Kimmeridgian Forced-fold Low displacement Thick salt Oxfordian- Kimmeridgian Displacement (Rotliegend) Triassic Salt Section 2 Fault drag High displacement Thin salt BC(U) discontinuity around dip Section 3 Normal extenstion No salt Thickness of salt Thickness of overburden Salt Triassic isochron Salt isochron Displacement Structural styles field scale Withjack and Callway (2000) 10 Classification: Open 25 oktober 2016 Statoil ASA

11 Forced-fold structural style Salt isochron (TWT) Section 1 Salt thickness: 400 ms Displacement: 800 ms Depocenter: away from the fault Triassic isochron Section 1 Signature : pillows onlap Less coupling, distributed deformation, less faulting more folding 11 Classification: Open 25 oktober 2016 Statoil ASA

12 Fault drag structural style 2/4-23S 2/4-22S Triassic isochron TWT Section 2 Salt thickness: 200 ms Displacement: 1400 ms Depocenter: away from the fault Salt isochron TWT 2/4-23S Section 2 Signature: faulted depocenter More coupling, focused deformation, more faulting, less folding 12 Classification: Open 25 oktober 2016 Statoil ASA

13 Fault extension structural style 2/4-16 Section 3 Salt thickness: 0 ms Displacement: 600 ms Depocenter: towards the fault 2/4-16 Section 3 Signature: wedges Coupling, focused deformation, rotation 13 Classification: Open 25 oktober 2016 Statoil ASA

14 Source to sink Hidra High MF3 Section 1 MF2 MF1 Hidra High Hidra High Section km2* 300 m eroded Triassic sufficient for King Lear and surounding King Lear look-alike Adjacent Kimmeridgian highs in 2.5 km2*20 m bonus source for King Lear in the South Key elements Sections 1 and 2: 1. BCU conform 2. Intra-Kimmeridgian Unconformity 3. Triassic subcrop BCU 4. MF2 and 3 forced-fold at Jurassic 5. Thin skinned tectonics (faulting, slumping?) 6. Triassic pod 7. MF2 and 3 normal extension at Rotliegend displacement 600 ms-1800 ms) 14 Classification: Open 25 oktober 2016 Statoil ASA

15 Decreasing NTG, increasing tectonic activity (Kimmeridgian climax) Conclusions Structural styles: Pod/Interpod and normal faulting/forced-folding influencing geometries of the stratigraphic packages hence sand distribution inside the stratigraphic packages Paleotopography controlled by salt tectonics /extension interaction Progradation from Hidra High (NW). Fault controlled, migrating multy-story depocenters. Potential in the levels above and below main reservoir. No confinement: King Lear look-alike surrounding Hidra High or other areas in Central Graben 15 Classification: Open 25 oktober 2016 Statoil ASA

16 Thank you Statoil and Total for permission to present the seismic interpretation which just represents the ideas of Statoil Field Development Early Phase His theory was proven wrong, but he proved it is possible Iren Måløy for advise on seismic data quality/demultiple techniques Einar Magerøy for advise on seismic tie Binyam Lema Alemu for petrophysics Tore Skar for advise on structural interpretation Lars Nørgård Jensen for advise on mapping techniques and structural interpretation 16 Classification: Open 25 oktober 2016 Statoil ASA

17 Upper Jurassic tectono-stratigraphic concept for King Lear (block 2/4): an old discovery and an eye-opener for Norwegian Central Grabenle Magdalena-Oana Badescu, geologistgeophysicist Field Development, Early Phase Statoil ASA This presentation, including the contents and arrangement of the contents of each individual page or the collection of the pages, are owned by Statoil. Copyright to all material including, but not limited to, written material, photographs, drawings, images, tables and data remains the property of Statoil. All rights reserved. Any other kind of use, reproduction, translation, adaption, arrangement, any other alteration, distribution or storage of this presentation, in whole or in part, without the prior written permission of Statoil is prohibited. The information contained in this presentation may not be accurate, up to date or applicable to the circumstances of any particular case, despite our efforts. Statoil cannot accept any liability for any inaccuracies or omissions.