Ocean bottom seismic in the oseberg south area j daniels

  • 1,477 views
Uploaded on

Ocean bottom seismic in the Oseberg South area by John Dangerfield, Jim Daniels, Per Riste, Mari Skaug and Vibeke Haugen

Ocean bottom seismic in the Oseberg South area by John Dangerfield, Jim Daniels, Per Riste, Mari Skaug and Vibeke Haugen

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
1,477
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
78
Comments
0
Likes
1

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide
  • Complex rift zone Nine structures Many compartments Significant uncertainy on depth and fluid contacts State the total number of wells. Total production 37.45 Sm3 since 1988. BUT the geophysical limits reached. Need to image much better than our conventional approaches – and if we can then there are considerable rewards. Highly mature large area. The easy drilling is done. The seismic image and reservoir models need to be much better to continue the recovery. Excellent economic potential if we can solve the problems
  • Animated slide
  • Animated slide F-12 B: 900 Sm 3 /day Costs: F-12 drilling and completion: 67 MNOK F12 A and B drilling and completion: 78 MNOK Total costs: 145 MNOK In the C area, we had drilled the 30/9-6 exploration well and the 30/9-F12, which was supposed to be the first producer. The seismic was awful. The well did not come in on prognosis and did not find sand.
  • Oligocene sands are the main reason for the poor image. The two wells are a kilometer apart showing the rapid
  • The problems are due to the Oligocene anomalies and their rapid variations. These are tur
  • NH9802 on the left, NH0402 on the right same location running E-W through the 30/9-6 well
  • Conclusion: Minimum 9 well spaced azimuths required Modelled effects assuming a flat Top Shetland
  • Animated slide
  • Oligocene anomalies: NH0506 volume peak reflectivity 1188 msec to 1976 msec (viewed as volume in HydroAVI)
  • OBC survey shot in 2005 model ready 2007
  • Our management recognised that we had made a substantial imporvement. We capitalised on the success quickly. J block also had awful data. In fact J had needed 12 sidetracks to obtain 2 producers, some of them due to seismic problems. We checked the acquisition parameters of 200 X 250 by decimating the C data in various ways and concluded that we could use a 300 X 300 configuration. This was a big saving in time and was one of the factors that resulted in the cost of the survey dropping by 50%.
  • J 12 two geological sidetracks, J 11 two sidetracks
  • Th

Transcript

  • 1. Ocean Bottom Seismic in the Oseberg South area John Dangerfield, Jim Daniels, Per Riste, Mari Skaug and Vibeke Haugen
  • 2. Ω C GC B J K GØ δ Oseberg Sør R
  • 3. Oseberg Sør Many areas of bad data… But we have great production wells C J
  • 4. Series of down stepping fault blocks Thin reservoirs – often little or no seismic expression Increasing erosion of Brent to east Omega G-Central Tune BCU Draupne /Heather UTarbert MT2 MT1 LT UNess LNess Coal Channel Sandstone J-Structure C-structure G-East BCU Draupne /Heather UTarbert MT2 UNess Coal Channel Sandstone Geological cross section through Oseberg Sør West East
  • 5. C-structure F-12, F12A and F-12 B. 30/9-6 Exploration well 1 km F-12 B:  Success! F-12:  Water wet F-12 A:  No sand 3 wells, payback time 80 days
  • 6. 1 km Dolomitised Oligocene sands Poor image
  • 7. 50 meters away Poor image 50 m away 1 km
  • 8. Sonic logs 1500 5000 m/s 30/9-6 30/9-13S 1500 5000 m/s Thin dolomitised sands Destroy the seismic image
  • 9. Top Shetland beneath an Oligocene sand Effect of dolomitised sands on the Seismic gathers
  • 10. The same seismic line… Acquired N-S Acquired E-W Dolomite sand Dolomite sand Different image Different image 30/9-6 30/9-6
  • 11. Effects of shooting orientation Shots Receivers Reflection point Reflection point Dolomite sands Dolomite sands
  • 12. Seismic 5000 m/s sand Sand model generated from surface seismic 2000 m/s overburden Model
  • 13. Top Shetland model (no sand)
  • 14. Overburden sands
  • 15. Magnified model Apparent faults Pull-up Low amplitude Top Shetland
  • 16. Real gathers Model gathers The model looks like the real data
  • 17. (11) (3) (5) (7) (1) Number of Azimuths FOLD 25 75 125 175 225 Model stack of Top Shetland with different numbers of azimuths Conclusion: Minimum 7 well spaced azimuths required
  • 18. What is OBC? Seismic receivers are on the seafloor Records both P-wave (compression) and S-wave (shear) We shoot crossline to get multiazimuth coverage from PGS Receivers Shot points
  • 19. Top Reservoir C-structure 30/9-6
  • 20. Top Reservoir C-structure With dolomite sands Multi-azimuth gives much better illumination OBC gather Single gather 2.5 km
  • 21. Dolomite sands C-structure Reservoir section C-structure 30/9-6 OLD DATA 2005 OBC DATA
  • 22. Marine data, reservoir section OBC data, reservoir section Base Cretaceous Top Lower Tarbert
  • 23. 2005 Model – Streamer 2007 Model – OBC C – STRUCTURE (same interpreter)
  • 24. OBC surveys Oseberg Sør C-structure OBC 2005 (25 Km 2 ) J-structure OBC 2008 (76 km 2 ) OBC surveys potential base 4D OBC surveys
  • 25. Streamer NH9802 Six cable marine acquisition Time migration
  • 26. 2008 OBC ST0823 OBC acquisition Fastrack PreSDM migration Processed in 6 weeks
  • 27. 2008 OBC Streamer
  • 28. 2008 OBC Streamer Oseberg Area Unit RC meeting 27.05.2009
  • 29. OBC NS and EW surveys Streamer 2004
  • 30. 2006 Model – Streamer data 2009 Model – OBC data J – STRUCTURE (same interpreter)
  • 31. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 32. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 33. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 34. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 35. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 36. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 37. Inversion results Suggest fluvial features Gas sand Oil sand Water sand? Shaley sand Shale Carbonate
  • 38. Why OBC?
    • Multiazimuth illumination:
      • Better structural image, better horizon identification, better investment decisions
    • Inversion is better: low frequencies, complete far offsets, S-wave data.
      • Possibility to identify sands and fluids
    • Monitoring production and injection effects:
      • Accurate 4D repeat position, plus PS data, no platform hole
    • Can be cheaper!
      • Sparser acquisition, less weather downtime, no 3D and 4D infill,
  • 39. what we aspire to:
    • Accurate maps for reservoir modelling
    • Accurate prognoses for planned wells (including drilling hazards)
    • Accurate lithology and fluid prediction from seismic
    • Production effects from 4D seismic
    • With a poor seismic image none of these goals is achievable
  • 40.
    • Seismic budget
    • Planning
    • Acquisition
    • Processing
        • Interpretation
          • Depth
            • Rock physics
            • Lithologies
            • Fluids
            • Production effects
  • 41. Ocean Bottom Seismic in the Oseberg South area John Dangerfield, Jim Daniels, Per Riste, Mari Skaug and Vibeke Haugen Presented by Dr Jim Daniels Principal Geophysicist [email_address] tel: +47 48151755 www.statoil.com Thankyou
    • The authors wish to thank the following partners for permission to publish this data:
    • ConocoPhillips Skandinavia AS
    • Petoro AS
    • Total E&P Norge
    • ExxonMobil Exploration and Production Norge AS.
    • The conclusions drawn are those of the authors alone.
  • 42. Classification: Internal 2010-05-03