1. Bedrock Delineation by a Seismic Reflection/Refraction Survey at TEAD Utah David Sheley and Jianhua Yu

2. Outline AcquisitionAcquisition Reflection ProcessingReflection Processing Refraction ProcessingRefraction Processing InterpretationInterpretation ConclusionsConclusions

3. Survey Location North 1 Mile Mandate: Image Bedrock Interface Bedrock Depth: 2 – 200? m

4. Acquisition Parameters 120 40-Hz geopones120 40-Hz geopones 5 m receiver spacing5 m receiver spacing 2.5 m source spacing2.5 m source spacing Split spreadSplit spread 2630 m total line length2630 m total line length 1056 shot gathers1056 shot gathers EWG source (5 stacks)EWG source (5 stacks)

5. EWG Source

6. Recording Parameters 1 ms sample interval1 ms sample interval 1500 samples/record1500 samples/record 120 active channels120 active channels 4-Hz low cut filter4-Hz low cut filter 500-Hz high cut (Nyquist) filter500-Hz high cut (Nyquist) filter

7. Outline AcquisitionAcquisition Reflection ProcessingReflection Processing Refraction ProcessingRefraction Processing InterpretationInterpretation ConclusionsConclusions

8. Reflection Processing Flow Reformat Data CSG, CRG Editing Band-Pass Filtering 10-50 Hz 10-50 Hz Automatic Gain Control (AGC)

9. Reflection Processing Flow Reformat Data CSG, CRG Editing Band-Pass Filtering 10-50 Hz 10-50 Hz Automatic Gain Control (AGC) Refraction and Refraction and Surface Wave Mute

10. CMP 1179: Trace Editing Time (ms) 0 400 200 800 1000

11. CMP 1179: SW and Refr. Mute Time (ms) 0 400 200 800 1000

12. Reflection Processing Flow Reformat Data CSG, CRG Editing Band-Pass Filtering 10-50 Hz 10-50 Hz Automatic Gain Control (AGC) Refraction and Refraction and Surface Wave Mute Velocity Analysis NMO Correction Residual Statics

13. Reflection Processing Flow Reformat Data CSG, CRG Editing Band-Pass Filtering 10-50 Hz 10-50 Hz Automatic Gain Control (AGC) Refraction and Refraction and Surface Wave Mute Velocity Analysis NMO Correction Residual Statics BP Filtering and BP Filtering and Amplitude Scaling F-X Prediction Filtering Filtering Trace Mixing and AGC Scaling AGC Scaling Output Result

14. Final Reflection Section: Time Time (ms) 0 400 200 800 01500100050025002000 Offset (m)

15. Final Reflection Section: Depth Depth (m) 0 400 200 800 01500100050025002000 Offset (m)

16. CMP’s 599 and 600 Time (ms) 0 400 200 800 1000

17. Final Reflection Section: Time Time (ms) 0 400 200 800 01500100050025002000 Offset (m) CMP 600 CMP 1180

18. CMP’s 1179 and 1180 Time (ms) 0 400 200 800 1000

19. Outline AcquisitionAcquisition Reflection ProcessingReflection Processing Refraction ProcessingRefraction Processing InterpretationInterpretation ConclusionsConclusions

20. 117,000 First Arrival Picks Time (ms) 0 400 200 800 1000

21. Inversion Parameters 117,000/127,000 picks117,000/127,000 picks 2.5 m grid size2.5 m grid size 2.5 m source spacing2.5 m source spacing 2730 x 220 m model (x,z)2730 x 220 m model (x,z) 160 x 80 max smoothing size160 x 80 max smoothing size 40 x 20 min smoothing size40 x 20 min smoothing size

22. Tomographic Residual Traveltime Residual (ms) 45 25 35 15 5 0 15 105 Iteration 160 x 80 40 x 20 80 x 40

23. Velocity Tomogram Depth (m) 0 200 100 0 1500 1000500 25002000 Offset (m) 0 4000 Velocity (m/s)

24. Tomogram & Raypath Density Depth (m) 0 200 100 0 1500 1000500 25002000 Offset (m) Depth (m) 0 200 100 0 1500 1000500 25002000 Offset (m) 0 4000 Velocity (m/s) 0 2500 # of Rays

25. Outline AcquisitionAcquisition Reflection ProcessingReflection Processing Refraction ProcessingRefraction Processing InterpretationInterpretation ConclusionsConclusions

26. Refraction/Reflection Comparison Depth (m) 0 200 100 0 1500 1000500 25002000 500 3000+ Velocity (m/s) Offset (m) Depth (m) 0200 100 0 1500 1000500 25002000 Offset (m)

27. Refraction/Reflection with Wells Depth (m) 0 200 100 0 1500 1000500 25002000 500 3000+ Velocity (m/s) Depth (m) 0 200 100 0 1500 1000500 25002000 Offset (m)

28. Interpretation Depth (m) 0 200 100 0 1500 1000500 25002000 500 3000+ Velocity (m/s) Depth (m) 0 200 100 0 1500 1000500 25002000 Offset (m)

29. Outline AcquisitionAcquisition Reflection ProcessingReflection Processing Refraction ProcessingRefraction Processing InterpretationInterpretation ConclusionsConclusions

30. Conclusions Refraction tomography provides confidence in the reflection image.Refraction tomography provides confidence in the reflection image. 40-Hz geophones did not sufficiently attenuate surface wave energy.40-Hz geophones did not sufficiently attenuate surface wave energy. Source induced noise contaminated near offset traces.Source induced noise contaminated near offset traces. The source produced adequate energy to image the bedrock contact.The source produced adequate energy to image the bedrock contact.