1. Interpreting a 3C-3D seismic survey, Ross Lake, Saskatchewan
Chuandong (Richard) Xu
and
Robert R. Stewart
CREWES Sponsors Meeting, Nov. 21, 2003

2. Outline Introduction Geology (channel sands)
3C-3D seismic and VSP data
Interpretation of PP & PS sections, isochrons, and Vp/Vs
Summary & Acknowledgements

3. Introduction Ross Lake located in southwestern Saskatchewan.
Target: Sandbars in Dimmock Creek Member of the Cantuar Formation of Mannville Group, Lower Cretaceous.
High porosity (>30%) and high permeability (3 Darcy).
Heavy Oil, 13° API.
4 vertical wells + 1 horizontal well in this area.
No gas cap, not waterflooded.

4. Geology
(from Vanbeselaere, 1995)
(from Christopher, 1974)

5. Acquisition of 3C-3D seismic survey
Shot in May, 2002
Field parameters:
Source: Dynamite m Depth
Group interval = 50 m
N-S shot-line spacing = 325 m
Receiver: 3C VectorSeis
E-W receiver-line spacing = 180 m
Record length: ms sample rate
CDP Bin size: 25m × 25m with fold of 45
After processing, NS Inline 1-91, EW Xline 1-132, about 7.5 km2

6. Map 25

7. Acquisition of the walkaway VSP
Shot in June, 2003
Zero-offset VSP: offset=53.67 m
Source: 1. Litton 315 vert-vibe
2. IVI horiz. mini-vibe
Offsets VSP: 400 m and 700 m with vert-source
200 m
Walkaway VSP:
offsets=150, 250, 560, 1000m with vert-source
Sweep: Hz for P-souce
5-100 Hz for S-souce
Downhole geophones spacing: 7.5m

8. Interpretation of seismic PP data
Crossline 11
Channel
West
East
IHACM

9. Inline 41 Channel South North
IHACM
The Xline 41, crossing the well It seems that all the events at the first 10 xlines are dipping upwards, statics?

10. XL81
XL41
XL11
East
West

11. Time slices T=1150 T=1120 T=1130 T=1160 T=1170 T=1140
A “V” shape at 1170 ms. Color key: red positive, blue negative.
T=1170
T=1140

12. Horizon maps (time structure)
Rush Lake
IHACM

13. Time thickness between RushLake and IHACM

14. Interpretation of PS seismic data
XL11, PS-radial
XL11, PS-transverse
PS time

15. PP XL11
PS XL11, constant Vp/Vs=2.35
PP time

16. Crossplot of P-velocity and S-velocity from 4 regional wells
Vp=1.50*Vs+964
Vp/Vs=1.5
Vp/Vs=2.0
Vp/Vs=3.0
Mudrock: Vp=1.16*Vs+1360

17. Amplitude Spectrum PP
PS-radial
PS-transverse

18. PP time, applied 5/10-50/60 bandpass filter
PP data
PS data, Vp/Vs=2.35 AND bulk shift UP 125ms
PS VSP (700m offset)

19. PS synthetic in PS time

20. PP synthetic (PP time)
PS synthetic (PS time)

21. Pick horizons on PS data
Xline 11
Xline 41
Xline 81

22. Horizon Maps (Time Structure)
PP data
RushLake
IHACM
PS data
RushLake
IHACM

23. PP time thickness RushLake-IHACM
PS time thickness RushLake-IHACM
Apparent Vp/Vs map between RushLake and IHACM

24. Summary PP time thickness indicates channels & sand bar shape
PS suggests sandy areas, shale cuts, & additional targets
Offset VSP helps correlations significantly
Zero-offset VSP gives interval Vp/Vs (1.6 to 3.3)
Synthetic seismograms increase confidence

25. Acknowledgements Husky Energy Inc.
Larry Mewhort, Kenneth Hedlin and Angela Ricci from Husky
Larissa Bezouchko from Schlumberger
Hampson-Russell for donating ProMC
Sponsors of CREWES