Transcript Maximum Entropy Migration: Preliminary Results

Autocorrelogram Migration
of Drill-Bit Data
Jianhua Yu, Lew Katz,
Fred Followill, and Gerard T. Schuster
Outline
Motivation and Objective
 Autocorrelogram Migration
 Examples

Synthetic Data
UPRC data

Summary
IVSPWD Objective
 Provide Look-ahead Image Below Drill Bit
 Reduce Uncertainty in Drilling
?
Problems



No Source Wavelet
No Source Initiation Time
Not Easy to Get Pilot Signal in
Deviated Well
Solution
Autocorrelogram Migration
No need
to know
source
wavelet
No need
to know
initial
time
No limits
to
deviated
well
Outline
. Motivation and Objective
. Autocorrelogram Migration
. Examples
. Summary
Well
Receiver
Ghost
Direct
Wave
Primary
Drill bit
Primary, Ghost and Direct Waves
Primary Autocorrelogram
Imaging Condition:
R
 sx  xg
D
 sg
Autocorrelate
Trace
g
 xg
s 
sx
x
 sg
Primary Autocorrelogram
Imaging Condition:
D*R
D*D
 xg
s 
sx
x
 sx  xg sg
}g
 sg
Primary Autocorrelogram
Imaging Condition:
  sx  xg  sg
p
BONUS:
Mitigates
src/rec statics!
g
 xg
s 
sx
x
 sg
Ghost Autocorrelogram Imaging
Condition:





sx
xx
xg
G
0
x
 xx
0
s
 sg
D
0
g
 xg
x x
0
x
0
Autocorrelate
Trace
 sg
Ghost Autocorrelogram Imaging
Condition:
D*G
x
 xx
0
s
D*D
0
 sx  x x  xg  sg
}
g
 xg
x x
0
x
0
0
 sg
Ghost Autocorrelogram Imaging
Condition:
  sx  x x  xg  sg
g
0
0
x
 xx
0
s
0
g
 xg
x x
0
x
 sg
Autocorrelogram Migration
m(x) 
..
 (rg , rs , )
s, g
Imaging Cond.
Migrated
Image
Autocorrelation
Function
Auto. Migration Procedure

Pre-process raw data
 Filter data
 Autocorrelate seismic traces:
d(rg , rs )

  d d
Autocorrelogram migration with
primary & ghost imaging conditions
Outline
. Motivation and Objective
. Autocorrelogram Migration
. Examples
. Summary
Geological Model
0
0
X (m)
4
Depth (m)
V1
V2
V3
V4
V5
3
V6
Velocity Model
X(km)
Depth(km)
0
0
4
0
0
X(km)
3.5
3.5
2.0
2.0
3
3
Interval Velocity
4
RMS Velocity
Autocorrelogram
Shot Gather
200
0
Time (s)
Traces
Time (s)
0
1
4
4
1
CSG 10
Traces
200
Primary Autocorrelogram
Depth Migration
X (km)
2.1
0
1.6
2.1
Depth (km)
0
1.6
X (km)
2.8
2.8
With primary+ghost
Without ghost
Ghost Autocorrelogram Depth
Migration
X (km)
1.6
X (km)
2.1
2.1
0
Depth (km)
0
1.6
2.8
2.8
With primary+ghost
Without ghost
Acquisition Survey
East (kft)
0
0
Drill bit
Well Rig
-5
Depth (kft)
0
10
4.5
Main Acquisition Parameters
Drill-bit Depth:
9188 ft
Offset Range:
1135-4740 ft
Recording Length: 20 s
Sample Interval:
2 ms
Station Number:
10
Main Processing Steps
Trace editing and static shift
Frequency panel analysis and noise elimination
Amplitude balance and energy normalization
Velocity analysis
Calculating cross- and autocorrelograms, vertical stacking
Cross- and Autocorelogram migration
Raw CGR 96
1
Trace #
Proc. CGR 96
10
1
Time (s)
0
7
5-40 Hz
Trace #
10
Autocorrelogram of CSG 96
1
10
1
10
1
10
Time (s)
0
4
8s
12 s
16 s
Autocorrlogram Migration Images
Primary Image
X(ft)
0
500
1
0
Ghost Image
X(ft)
500
1
Time (s)
No reflections
3.2
3.2
Correlation Window = 8 s
Acquisition Survey Map
Well Rig
North (ft)
0
Drill bit
-5000
0
1500
3000
East (ft)
4500
SP
1265
1235
1215
1.0
Time (s)
Drill
hole
2.0
3.0
Primary Autocorrelogram Image (Corr. window=8 s)
SP
1255
1235
1215
1.0
Drill
Time (s)
hole
2.0
3.0
Ghost Autocorrelogram Image(Corr. window=8 s)
SUMMARY
Autocorrelation Migration:
No need to know wavelet or start time
Mitigates src/rec static
Compresses wavelet
Auto migration images show rough
correlation to surface-CDP section
Works for deviated wells
Beware of virtual multiples!
Acknowledgements
• We appreciate DOE’s Financial support
• We are grateful to Union Pacific
Resources Corp. for donating this data
• I thank the sponsors of the UTAM
consortium for their financial support
SUMMARY
Difficulty of separating upgoing
and downgoing wave can cause
artifacts in migration image
What is Next
Improve the method for realtime purpose
Reduced the virtual multiple and
other wave influence
Developing 3D autocorrelogram
method
Primary Autocorrelogram
Time Migration
2.1
1.6
X (km)
Time (s)
0
1.6
X (km)
2.2
With primary+ghost
Without ghost
2.1
Ghost Autocorrelogram
Time Migration
2.1
1.6
X (km)
Time (s)
0
1.6
X (km)
2.2
With ghost+primary
Without primary
2.1
Outline
. Objective
. Autocorrelogram Migration
. Examples
. Summary

Processed CSG 96
Time (s)
0
7
10
1
0.5
Time (s)
1
Part of CRG 6
4.5
5-40 Hz
13
Drill-bit Data of CSG #96
Time (s)
0
7
1
Trace Number 10
Frequency Panel Analysis
1
0
0
Time (s)
10
Time (s)
1
7
7
< 5 Hz
10
5-15 Hz
Frequency Panel Analysis
1
0
0
Time (s)
10
Time (s)
1
7
7
15-25 Hz
10
25-40 Hz