Macroscope Field Test Sherif M Hanafy 27 October 2014 Outline Problem Theory Introduction to SSTM Numerical Tests Elastic synthetic examples Field example Conclusions Future Work Outline ID: 512342
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Slide1
Fault Detection by Surface Scanning Tunneling Macroscope: Field Test
Sherif M. Hanafy27 October 2014Slide2
OutlineProblemTheory: Introduction to SSTM
Numerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide3
OutlineProblem
Theory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide4
Problem
Problem: Detection of the presence of
near-surface impedance anomalies and faults
Solution:
Seismic scanning tunneling
macroscope
(SSTM) methodSlide5
Outline
ProblemTheory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide6
Prestack
Migration:
Migration image
m(
x,s
)
Prestack
Migration
x
e
V
s
direct
scattered
s
Migration profiles
B
Mig
. Kernel
DataSlide7
Prestack
Migration:
Prestack
Migration
x
e
V
1. Eliminate green image
and keep profiles
direct
scattered
s
BSlide8
Prestack
Migration
x
e
V
1. Eliminate green image
and keep profiles
2. Lower recording plane
to just above
scatterer
3. Only keep profile on
recording
plane
s
e
B
direct
scattered
s
B
Prestack
Migration
:
Slide9
Prestack
Migration:
Prestack
Migration
x
e
V
direct
scattered
s
B
1. Eliminate green image
and keep profiles
2. Lower recording plane
to just above
scatterer
3. Only keep profile
on
recording plane
s
e
B
4. Eliminate data. Migration
profile
SSTM m(
x,
s
)
m(
x,
s) x ε B so G(g|x)G(x|s) = recorded data and no migration velocity needed
Mig
. KernelData
Data
Slide10
Theory
Pre-stack SSTM profiles
Source Location (s)
Trial Location
Pre-stack SSTM Profiles
B
0
400 m
SSTM
Profile
Slide11
Pre-stack SSTM Profiles
Source Location (s)
Trial Location
Theory
Trial Location
Stacked SSTM
ProfileSlide12
OutlineProblem
Theory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide13
Numerical Tests
3-Scatterers Velocity Model
Depth to
scatterer
clusters
Cluster # 1: 0.1
λ
Cluster #
2: 0.3
λ
Cluster #
3: 0.4
λSlide14
Shot Gather Example
Halo and Mute Early-arrivals
Time (s)
X (m)
0.0
400
0.0
0.7
Common Shot Gather # 200
P
S
Halo
Mute early-arrivals
Practical problems
Zero and near offset traces
Early
arrivalsSlide15
Halo Test
Pre-stack SSTM
Stacked SSTM
Source Location (s)
Trial Location
Scatterers
are not clearly shown on the SSTM profilesSlide16
Mute Early-arrivals Test
Pre-stack SSTM
Stacked SSTM
Source Location (s)
Trial Location
Scatterers
are shown on both the pre-stacked and the stacked SSTM profilesSlide17
OutlineProblem
Theory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide18
Field TestSlide19
Data CollectionSlide20
Shot Gather Sample
Shot Gather # 1
No
. of
sor
. = no. of rec. =
120
Sor
.
int
. = rec. int. =
2.5
m
Source
is a 200
lb
weight dropSlide21
0
400
Offset
(m)
0
5
0
Z
(m)
Velocity (m/s)
400
2800
Traveltime
Tomogram
a
F
b
c
d
Ground truth:
The 1995 fault ruptureSlide22
Shot Gather Sample
Shot Gather # 1Slide23
a
F
b
c
d
a
F
b
c
d
SSTM Profiles
Pre-stacked SSTM
Stacked SSTM
F
a
b
c
d
X
XSlide24
SSTM Profiles
Pre-stacked SSTM
Stacked SSTM
Band pass
t
est, 5 – 15 Hz pass, peak freq. = 35 Hz.
a
F
b
c
d
a
F
b
c
d
F
a
b
c
d
X
X
F
c
d
bSlide25
OutlineProblem
Theory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide26
Conclusions
SSTM can be used to locate near-surface impedance anomalies and faults.Elastic Synthetic examples show that scatterers need to be very close to source line.
SSTM tested on a field data, where fault and colluvial wedges can be located with SSTM methodSlide27
Possible ApplicationsNear-surface fault detection
Near-surface local anomaly detectionQC for velocity tomogramsLocate near-surface bodies such as pipes, archeology, etc.Slide28
OutlineProblem
Theory: Introduction to SSTMNumerical TestsElastic synthetic examplesField exampleConclusionsFuture WorkSlide29
Future WorkSynthetic tests using more complex velocity model
Apply f-k filter to isolate scatterer effect on the shot gathersSlide30
Acknowledgements
I would like to thank The CSIM sponsors for their supportThe students of the ‘Geophysical Field Methods’ class for their help in data collectionThank You