Transcript No Slide Title

2001 Sponsors
• Aramco
• Amerada Hess
• BP-AMOCO
• Chevron
• Conoco
• Japan Nat. Oil
Co.
• Inst. Mex. Pet.
• INCO
• Marathon
• Phillips
• Sisimage
• Texaco
• Veritas
Salient 2001 Research
Achievements
1. Wave-Beam Migration
Migration Accuracy vs $$$
Full-Wave
Wave-Beam
Phase-Shift
No Approx.
Multiples
Ray-Beam
Anti-aliasing
Kirchhoff
Expense
Smear Reflection along Wavepath
Slant Stack
S
R
Image
Point
Fresnel Zone
Wavefront FD
0
1.5 km
0
4.5 km
Standard FD
Cost Ratio of Standard /Wavefront
Cost Ratio
45
5
500
# Gridpts along side
3000
Model
0
2.2 km/s
1.5 km/s
1.8 km/s
1.5 km
Prestack Migration Image
0
1.5 km
0
4.5 km
Eikonal Traveltime Field
Depth (kft)
0
3
0
Distance (kft)
5
Wave-Equation Traveltime Field
Depth (kft)
0
3
0
Distance (kft)
5
Model
Depth (km)
0
3
0
Distance (km)
5
Wave Equation Traveltimes
Kirchhoff
Depth (kft)
5
11
0
Distance (km)
5
0
Distance (km)
5
Wavefront Reverse Time Migration
1. Order Mag. Cheaper than 3-D RT
2. Fewer Artifacts
3. Optimal Accuracy
Open Questions
1. More Storage
2. Resorting Overhead
3. Large scale tests?
Salient 2001 Research
Achievements
1. Wave-Beam Migration
2. Multiple Removal POIC
Multiple Removal by
Primary-Only Imaging Condition
Hongchuan Sun
Forward Modeling
Primary
S
Multiple
S
R
R
R
S
Depth
Depth
S
R
Distance
Distance
Migration with POIC
S
S
Depth
The rays
intersect
at point P,
and the
traveltime
R
R
P
 + =obs
SP
RP
Distance
Multiple Removal
S
 +
SP
RP
= obs
R
S
Depth
The rays
never
intersect;
or the
traveltime
R
P
Distance
SEG/EAGE 2-D Salt Data
Depth (kft)
0
Model
Depth (kft)
11
0
KM Image
11
Depth (kft)
0
POIC Image
11
0
Distance (kft)
51
Offsets Used: 0 ~ 14000 ft
Model
Depth (kft)
5
11
15
Distance (kft)
KM Image
51
POIC Image
Depth (kft)
5
11
15
Distance (kft)
51 15
Distance (kft)
51
Offsets Used: 0 ~ 14000 ft
KM Image
Model
POIC Image
Depth (kft)
0
11
0
Distance (kft)
17 0
Distance (kft)
17 0
Distance (kft)
17
Offsets Used: 1600 ~ 14000 ft
KM Image
Model
POIC Image
Depth (kft)
0
11
0
Distance (kft)
17 0
Distance (kft)
17 0
Distance (kft)
17
Conclusions
• POIC effectively remove surface
related multiples
• POIC performs much better when
near-offset data are not used
• POIC should be applicable to
interbed multiple removal
Salient 2001 Research
Achievements
1. Wave-Beam Migration
2. Multiple Removal POIC
3. Sparse Fequency Migration
Fourier Finite Difference
Migration with Sparse
Frequencies
Jianhua Yu
Department of Geology & Geophysics
University of Utah
Objective

Improve computational efficiency
of wave-equation extrapolation

Hi-quality Image
Frequency Domain Migration
o
70 Fourier Finite Difference Method
1/4 Sparser Frequency Domain Sampling
Comparison of 3D Impulse Response
0
X (km)
4
Depth (km)
0
FD algorithm
2.4
Depth (km)
0
2.4
Main energy
wider angle FFD
2D Impulse Response
(Velocity contrast, i.e., V/Vmin = 3.0)
0
X (km)
4 0
X (km)
4
Depth (km)
0
2.4
Standard wider angle
FFD
Main energy wider angle
FFD
Comparison of FFD and Main Energy FFD
Migration
0
X (km)
4
Depth (km)
0
FFD algorithm
2.4
Depth (km)
0
2.4
Main energy
FFD
(computational
time saving
about 38 %)
3D SEG/EAGE Zero Offset Imaging Result
0
X (km)
2.0
0
0
Y (km)
0
X (km)
4
0
2.0
8
Y (km)
Depth (km)
Depth (km)
0
4
8
Strengths:
Efficient forward extrapolation
Wider angle FFD operator
Less numerical anisotropy in 3D by
applying high order implicit FD algorithm
Weaknesses:
Coding Complexity
Fewer Frequencies
Reduced Quality
Salient 2001 Research
Achievements
1. Wave-Beam Migration
2. Multiple Removal POIC
3. Sparse Fequency Migration
4. AVO Migration Decon
Prestack Migration Decon
for AVO Analysis
Jianhua Yu
Department of Geology & Geophysics
University of Utah
Reason:
T
m = L dL rbut
Migrated
Section
d =Lr
Data
Migration Section = Blured Image of r
Solution: Deconvolve the point
scatterer response from the migrated
image
T
-1
r = (L L)m
Reflectivity
Migrated
Section
Objective of PMD AVO

Suppress unwanted interference
 Increase
estimation accuracy of AVO
parameters
 Enhance
resolution of AVO sections
Zoom View of AVO parameter Section
Before and After PMD
X(km)
X(km)
1.0
1.0
2.0
2.0
0.5
Time (s)
Time (s)
0.5
2.0
2.0
Before PMD
After PMD
Migration CRG Before and After PMD
Trace
Trace
1
60
60
Time (s)
0.6
Time (s)
0.6
1
1.8
1.8
Before PMD
After PMD
Comparison of Amplitude & Angle
Estimation Before and After PMD
2rd layer
1st layer
3rd layer
Amplitude
1
0
0
Angle
60 0
+: Before PMD
Solid line: Theoretical value
Angle
60 0
*: After PMD
Angle
60
Summary & Future
• MD reduces artifacts
• MD improves resolution & AVO
• MD field data case by Feb.
Salient 2001 Research
Achievements
1. Wave-Beam Migration
2. Multiple Removal POIC
3. Sparse Fequency Migration
4. AVO Migration Decon
5. Joint Autocorrelation Imaging
Joint Imaging Using Both Primary
and Multiple for IVSP Data
Jianhua Yu
Department of Geology & Geophysics
University of Utah
Problems for Deviated and
Horizontal well

No Source Wavelet & Initiation Time
 Not
Easy to Get Pilot Signal in
 Hard

to Separate Primary and Ghost
Static Shift at Source and Receiver
Auto. Imaging using Primary and Ghost
Geological Model
0
0
X (m)
4
Depth (m)
V1
V2
V3
V4
V5
3
V6
Shot Gather and Autocorrelogram
200
0
Time (s)
Traces
Time (s)
0
1
4
4
1
Traces
200
Eliminate Interferences using Joint
Imaging in Time Domain
2.1
1.6
X (km)
Time (s)
0
1.6
X (km)
2.2
Standard Migration
Joint Migration
2.1
Eliminate Interferences using Joint
Imaging in Depth Domain
X (km)
2.1
1.6
2.1
Depth (km)
0
1.6
X (km)
2.8
Conventional Imaging
Joint Imaging
Kirchhoff and Auto. Migration with
Statics Error at Source and Receiver
X (km)
2.0
1.6
Depth (km)
0
1.6
X (km)
2.8
Kirchhoff joint migrationg
Auto. joint migrationg
2.0
SUMMARY
Joint Migration method:
Works for deviated and horizontal well
Eliminating static shift errors
Avoiding separating primary and ghost
waves for horizontal well data
Don’t require pilot signal & wavelet
initial time
Salient 2001 Research
Achievements
1. Wave-Beam Migration
2. Multiple Removal POIC
3. Sparse Fequency Migration
4. AVO Migration Decon
5. Joint Autocorrelation Imaging
6. Xwell Statics & Tomography
INCO Project Report
M. Zhou
Geology and Geophysics Department
University of Utah
Objective
Invert velocity & geometry jointly
Velocity (km/sec)
Normalized Traveltime Residuals vs.
Velocity & Geometry Changes
2.5
1.0
5.0
0.5
7.5
0.0
-250
0.0
Horizontal shift (m)
500 m
V=5.0km/sec
250 -250
0.0
Vertical Shift (m)
250 -30
0.0
Rotation (degree)
30
Problems
1) Geometry is coupled with
velocity
2) Joint inversion is ill-posed
Geometry Error: synthetic example I
a) Synthetic Model
0
b) Standard Inversion with 10 m shot shift
Km/s
5.0
Depth (m)
4.5
100
3.0
200
0
c) Joint Inversion for the shot shift
( all shots have the same shift )
2.5
80
10
80 -10
d) Joint Inversion + a priori information
for individual shot locations
Km/s
0
5.0
Depth (m)
4.5
100
3.0
200
-10
0
Offset (m)
80 -10
0
Offset (m)
80
2.5
Geometry Error: synthetic example II
a) Synthetic Model
b) Standard Inversion without shot shift
Km/s
0
Depth (m)
3.2
100
2.8
200
2.4
300
-10
2.0
80
10
100 -10
0
c) Standard Inversion with +10 m shot shifts d) Joint Inversion for the shot shift
Km/s
0
Depth (m)
3.2
100
2.8
200
2.4
300
-10
2.0
0
Offset (m)
80 -10
0
Offset (m)
80
Geometry Error: synthetic example II
a) Synthetic Model
b) Standard Inversion without shot shift
Km/s
0
Depth (m)
3.2
100
2.8
200
2.4
300
-10
2.0
c) Joint Inversion + a priori information
for the shot shift
80
10
100 -10
0
d) Joint Inversion + a priori information
for individual shot locations
Km/s
0
Depth (m)
3.2
100
2.8
200
2.4
300
-10
2.0
0
Offset (m)
80 -10
0
Offset (m)
80
Conclusions
Joint inversion
• works for simple model
• needs additional information