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Shallow P and S velocity structureRed Deer, Alberta
Don Lawton, Meredith McArthurRachel Newrick & Sarah Trend
Cygnet field, Red Deer, Alberta
Stratigraphy of the Ardley coals
Cased hole logs, Cygnet
Vertical Vp/Vs
Vertical component, walkway VSP
100 m 150 m
244 m191 m
P-wave first arrival traveltime analysis
P-wave velocity model and turning rays
Vertical component
( )
100 m 150 m 191 m 241 m
Radial component
100 m 150 m 191 m 241 m
Transverse component
100 m 150 m 191 m 241 m
SV-wave first arrival traveltime analysis
0
50
100
150
200
250
300
200 250 300 350 400
Time (ms)R
ecei
ver D
epth
(m)
Observed Modeled
SV-wave velocity model and turning raysVo(m/s) k(s-1)
425 7
600 8
850 6
1180
1200 10
1450 18
1000 12
1300
0
24
55
105
180
205
240
255
Dep
th (
m)
P-wave incident angle at well
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Calculated Observed
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Calculated Observed
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Calculated Observed
θ
P-wave
SV-wave incident angle at well
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Observed Calculated
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Calculated Observed
0
50
100
150
200
250
300
-60 -40 -20 0 20 40 60 80
Incident Angle
Dep
th (m
)
Calculated Observed
θ
SV-wave
Conclusions
• Turning rays are present at Cygnet
• Velocity gradients up to 10 s-1 for P-waves
• Velocity gradients up to 8 s-1 for SV waves
• Weak P-wave anisotropy observed
• Incident angle analysis generally supports raytracing results
• Study provides insights into P-S statics
Acknowledgements
• CREWES sponsors• NSERC• Alberta Energy Research Institute• Cygnet project sponsors• GX-Technology• Landmark Graphics• Alberta Ingenuity Fund
