Survey Design and Automated Acquisition of Near-Surface 3D Seismic Reflection Data

223 Pages·2009·13.74 MB·English

Ultra-Shallow Imaging Using 2D & 3D Seismic Reflection Methods

by

Steven Daniel Sloan
B.S., Millsaps College, 2003
M.S., The University of Kansas, 2005

Submitted to the Department of Geology
and the Faculty of the Graduate School of The University of Kansas
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
2008

Advisory Committee:

____________________________
Don W. Steeples, Chair

____________________________
Georgios P. Tsoflias

____________________________
Carl D. McElwee

____________________________
Jennifer A. Roberts

____________________________
Robert L. Parsons

Date Defended:___________________________
The Dissertation Committee for Steven Sloan certifies that this is the approved
version of the following dissertation:

Ultra-Shallow Imaging Using 2D & 3D Seismic Reflection Methods

Advisory Committee:

____________________________
Don W. Steeples, Chair

____________________________
Georgios P. Tsoflias

____________________________
Carl D. McElwee

____________________________
Jennifer A. Roberts

____________________________
Robert L. Parsons

Date Approved:___________________________

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Abstract
The research presented in this dissertation focuses on the survey design,
acquisition, processing, and interpretation of ultra-shallow seismic reflection (USR)
data in two and three dimensions. The application of 3D USR methods to image
multiple reflectors less than 20 m deep, including the top of the saturated zone (TSZ),
a paleo-channel, and bedrock, are presented using conventional acquisition methods
and a new automated method of acquiring 3D data using hydraulically planted
geophones. Processing techniques that focus on near-surface problems, such as
intersecting reflection hyperbolae caused by large vertical velocity changes and
processing pitfalls, are also discussed. The application of AVO analysis of 2D USR
data collected during a pumping test yielded amplitude variations related to the
thickness of the partially saturated zone that correlated spatially and with changes in
pumping. USR methods were also used to image the TSZ less than one meter deep,
the shallowest TSZ reflection to date.

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Acknowledgments
I would like to thank my wife Becky first and foremost for putting up with all
of the late nights and weekends spent in the office and for supporting me along the
way. I would also like to especially thank Don Steeples for his guidance and
mentoring. I like to think that I have come a long way as a scientist since I first came
to KU and it would not have been possible without him. Thanks to my committee
members George Tsoflias, Jennifer Roberts, Carl McElwee, and Robert Parsons for
serving on the committee and providing helpful suggestions and edits along the way.
Dr. Parsons has been very generous in letting us use his property as a test site for the
past several years and for that I am very grateful. Rick Miller provided financial
support over my last year and made suggestions that have improved the quality of the
final results of the Autojuggie research. I would also like to thank the numerous
graduate students who have contributed their time in the field over the years,
including: Paul Vincent, Rob Eslick, Gerard Czarnecki, Jon Jarvis, Ben Rickards,
Brian Miller, Brooke Perini, and Kwan Yee Cheng.

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Table of Contents
Chapter 1: 3D Seismic Reflection Methods
1) Introduction 2
2) Historical Perspective 2
3) Previous 3D Shallow Seismic Reflection Surveys 8

Chapter 2: Overview of 3D Seismic Survey Design
1) Introduction 12
2) Offset & Azimuth Distributions 17
3) Aspect Ratio 23
4) Planning a Land 3D Seismic Survey 27
5) Acquisition Footprints 31
6) Shallow 3D Survey Design Considerations 37

Chapter 3: Applying 3D seismic reflection methods to the ultra-shallow subsurface
1) Introduction 48
2) Survey Design & Acquisition Parameters 53
3) Data Processing 57
4) Results & Discussion 61
5) Conclusions 66

Chapter 4: The 3D Autojuggie: Automating 3D near-surface seismic data acquisition
1) Introduction 69
2) Prior Work 71
3) 3D Autojuggie Description & Operation 75
4) Initial Testing & Results 79

Chapter 5: 3D Autojuggie Survey Design & Acquisition
1) Introduction 84
2) Walkaway Test 84
3) 3DAJ Survey Design 90
4) Field Acquisition 93

Chapter 6: 3D Autojuggie Processing & Results
1) Introduction 99
2) Processing 101
3) Results 108
4) Discussion 119
5) Conclusions 120

Chapter 7: Seismic response to partial water saturation
1) Introduction 123
2) Data Acquisition & Processing 130
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3) AVO Analysis 132
4) AVO Results 136
5) Frequency Effects 139
6) Frequency Results 141
7) Conclusions 144

Chapter 8: Acquisition and processing pitfall associated with clipped near-surface
seismic reflection traces
1) Introduction 146
2) Data Acquisition & Processing 148
3) Results 149
4) Discussion 153
5) Conclusions 157

Chapter 9: Ultra-shallow imaging of the top of the saturated zone
1) Introduction 160
2) Geologic Setting 162
3) Data Acquisition & Processing 163
4) Results 164
5) Conclusions 168

Chapter 10: Summary & Conclusions
1) Summary & Conclusions 170

References 175

Appendix A: Current Abstracts & Publications 181

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List of Figures
Figure 1.1 Correlation shooting method 4
Figure 1.2 Star-shaped shooting pattern 4
Figure 1.3 Comparison of common-source and cross spreads 6
Figure 2.1 Illustration of survey design terms 14
Figure 2.2 Fold map of a 4x48 patch 16
Figure 2.3 Fold map comparison of rolling spreads 16
Figure 2.4 Offset-distribution plot 18
Figure 2.5 Offset-redundancy plot 20
Figure 2.6 High-fold CMP gather with poor offset distribution 21
Figure 2.7 Azimuth-distribution plot 21
Figure 2.8 Azimuth-redundancy plot 23
Figure 2.9 Aspect ratio comparison 24
Figure 2.10 Trace count plots 25
Figure 2.11 NAZ versus WAZ plots 26
Figure 2.12 Comparison of full-fold and swath geometries 34
Figure 2.13 Acquisition footprint versus survey design 35
Figure 2.14 Aspect ratio time slice comparisons 36
Figure 2.15 Example 2D common-shot gather 39
Figure 2.16 Angle-of-incidence trace counts for a NAZ patch 41
Figure 2.17 Angle-of-incidence trace counts for a WAZ patch 41
Figure 2.18 2D CMP gathers before and after NMO correction 43
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Figure 2.19 2D CMP gathers before and after NMO correction 43
Figure 2.20 Filtering effects of clipped traces 45
Figure 2.21 2D CMP gather from a survey acquired near Lawrence, Kansas 46
Figure 3.1 3D survey site map 50
Figure 3.2 NMO-related artifacts from intersecting reflections 52
Figure 3.3 Previously acquired 2D CMP gather 54
Figure 3.4 3D survey design and attributes 55
Figure 3.5 3D common-shot gather, sorted by receiver line 56
Figure 3.6 Comparison of fold plots before and after trace editing 57
Figure 3.7 Offset-sorted raw 3D shot gather 59
Figure 3.8 Frequency-amplitude spectra of a 3D shot gather 60
Figure 3.9 Comparison of sections NMO corrected with different mutes 62
Figure 3.10 Comparison of stacked processing subsets 63
Figure 3.11 3D chair diagram 64
Figure 3.12 3D interpreted surfaces 64
Figure 3.13 Interpreted channel surface 65
Figure 3.14 Interpreted and uninterpreted time-amplitude slices 66
Figure 4.1 Photo of 2D pilot array 74
Figure 4.2 Walkaway comparison of the pilot array 75
Figure 4.3 Photos of 3DAJ transition 76
Figure 4.4 Photos of the 3DAJ geophone planting procedure 77
Figure 4.5 Photo of differing spike lengths 78
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Figure 4.6 3DAJ walkaway test diagram 80
Figure 4.7 3DAJ walkaway test data 81
Figure 4.8 3DAJ walkaway test data frequency-amplitude spectra 82
Figure 5.1 3DAJ survey site map 86
Figure 5.2 Walkaway test layout 87
Figure 5.3 Walkaway test data 87
Figure 5.4 Comparison of multiple shots in a single hole 88
Figure 5.5 Multi-shot frequency-amplitude spectra 89
Figure 5.6 3DAJ survey layout and fold map 91
Figure 5.7 3DAJ survey offset and azimuth distribution plots 92
Figure 5.8 3DAJ offset-redundancy plot 93
Figure 5.9 3DAJ field photographs 94
Figure 6.1 Raw shot gather with TSZ reflection 100
Figure 6.2 Raw shot gather with S2 reflection 100
Figure 6.3 Raw shot gather with S1 and BR reflections 101
Figure 6.4 Fold-map comparison after trace editing 102
Figure 6.5 CMP gather with interpreted reflections 103
Figure 6.6 CMP gather with early and surgical mute overlays 104
Figure 6.7 Shot gather and corresponding f-k spectrum 105
Figure 6.8 Same as 6.7 with overlain interpretations 105
Figure 6.9 CMP gather with subset overlays 106
Figure 6.10 TSZ reflection before and after statics 108
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Figure 6.11 Interpreted CMP-stacked line 109
Figure 6.12 Interpreted 3D chair diagram 111
Figure 6.13 Interpreted 3D surfaces 112
Figure 6.14 Top and bottom views of S2 surface and time slices 113
Figure 6.15 S-SW view of interpreted surfaces 114
Figure 6.16 3D view of surfaces from the south 115
Figure 6.17 Illustration of sediments encountered while drilling 116
Figure 6.18 Plot of average down-hole seismic velocity with depth 117
Figure 7.1 Clay Center, Kansas site map 125
Figure 7.2 Diagram of water table before and after pumping 126
Figure 7.3 Plot of P-wave velocity versus water saturation 127
Figure 7.4 Illustration of patchy and uniform saturation curves 128
Figure 7.5 Illustration of effects of a ramp-velocity function 130
Figure 7.6 CMP-stacked sections during different pumping stages 132
Figure 7.7 CMP supergather 133
Figure 7.8 AVO curves during drainage and imbibition 135
Figure 7.9 AVO curves for pumping and no pumping 136
Figure 7.10 Illustration of subsurface model for the PSZ 139
Figure 7.11 Synthetic traces representing PSZ changes 140
Figure 7.12 Frequency changes with changes in pumping stress 142
Figure 7.13 Modeled frequency changes versus PSZ thickness 143
Figure 8.1 Field files comparing clipping with different sources 147
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