reverse time migration of prism waves for salt flank delineation
DESCRIPTION
Reverse Time Migration of Prism Waves for Salt Flank Delineation. Wei Dai, WesternGeco Gerard T. Schuster, King Abdullah University of Science and Technology. Sep 25, 2013. Outline. Introduction and motivation Theory Numerical Results L model Salt model Summary. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/1.jpg)
Reverse Time Migration of Prism Waves for Salt Flank Delineation
Wei Dai, WesternGecoGerard T. Schuster, King Abdullah University
of Science and Technology
Sep 25, 2013
![Page 2: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/2.jpg)
Outline• Introduction and motivation
• Theory
• Numerical Results
L model
Salt model
• Summary
![Page 3: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/3.jpg)
Introduction• Problem: Vertical boundaries (salt flanks) are
difficult to image because they are usually not illuminated by primary reflections.
• Solution: Prism waves contain valuable information.
![Page 4: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/4.jpg)
Conventional Method• When the known boundaries are embedded in
the velocity model, conventional RTM can migrate prism waves correctly.
![Page 5: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/5.jpg)
Recorded Trace
Time (s) 20
![Page 6: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/6.jpg)
Horizontal Reflector Embedded in the Velocity0
Z (k
m)
3
0 X (km) 6
0Z
(km
)3
Conventional RTM Image
![Page 7: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/7.jpg)
Reverse Time Migration Formula
𝒎𝒎𝒊𝒈(𝒙)=∑𝝎𝝎𝟐𝑾 ∗(𝝎 )𝑮∗ (𝒙|𝒔 )𝑮∗ (𝒙|𝒈 )𝒅 (𝒈|𝒔 )
Angular Freq. Source SpectrumGreen’s functions
Input Data
0Z
(km
)3
𝒙
𝑮 (𝒙|𝒔 )=𝑮𝒐 (𝒙|𝒔 )+𝑮𝟏(𝒙∨𝒔)𝑮 (𝒙|𝒈 )=𝑮𝒐 (𝒙|𝒈 )+𝑮𝟏(𝒙∨𝒈 )
![Page 8: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/8.jpg)
+ 𝑮𝒐∗ (𝒙|𝒔 )𝑮𝒐
∗ (𝒙|𝒈 ) 𝒅𝟐 (𝒈|𝒔 )
+ +
+ + + Other terms.]
0 X (km) 6
0Z
(km
)3
Ellipses
Rabbit Ears
Prism Wave Kernels
![Page 9: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/9.jpg)
𝒎𝒎𝒊𝒈=∑𝝎𝝎𝟐𝑾 ∗ (𝝎 )𝑮𝟏
∗ (𝒙|𝒔 )𝑮𝒐∗ (𝒙|𝒈 )𝒅𝟐 (𝒈|𝒔 )
𝑮𝟏❑ (𝒙|𝒔 )=∫𝝎𝟐𝒎 (𝒙 ′)𝑮𝒐 (𝒙 ′|𝒔 )𝑮𝒐 ( 𝒙′|𝒙 )𝒅𝒙 ′
Born Modeling
0Z
(km
)3
0 X (km) 6
Migration of Prism Waves
![Page 10: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/10.jpg)
Migration of Prism Waves0
Z (k
m)
30
Z (k
m)
3 0 X (km) 6
𝑥𝑠𝑥𝑔
𝑥1
𝑥2
|𝑥𝑠−𝑥2 ′|𝑐 +
|𝑥2−𝑥𝑔|𝑐 =𝜏𝑠𝑔
𝑥2❑ ′
![Page 11: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/11.jpg)
𝒎𝒎𝒊𝒈=∑𝝎𝝎𝟐𝑾 ∗ (𝝎 )𝑮𝒐
∗ (𝒙|𝒔 ) 𝑮𝟏∗ (𝒙|𝒈 )𝒅𝟐 (𝒈|𝒔 )
𝑮𝟏❑ (𝒙|𝒈 )=∫𝝎𝟐𝒎 ( 𝒙′ )𝑮𝒐 (𝒙 ′|𝒔 )𝑮𝒐 (𝒙 ′|𝒙 )𝒅𝒙 ′
Born Modeling
0Z
(km
)3
0 X (km) 6
Migration of Prism Waves
![Page 12: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/12.jpg)
Migration of Prism Waves0
Z (k
m)
30
Z (k
m)
3 0 X (km) 6
![Page 13: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/13.jpg)
Outline• Introduction and motivation
• Theory
• Numerical Results
L model
Salt model
• Summary
![Page 14: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/14.jpg)
0Z
(km
)3 0 X (km) 6
The L Model• Model size: 301 x 601 • Source freq: 20 hz• shots: 32 • geophones: 601
![Page 15: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/15.jpg)
0Ti
me
(s)
6.4
0 X (km) 6
A Shot Gather of the L Model
![Page 16: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/16.jpg)
0Z
(km
)3
0 X (km) 6
0Z
(km
)3
Prism Wavepath
![Page 17: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/17.jpg)
0Z
(km
)3
0 X (km) 6
0Z
(km
)3
Migration Image of Prism Waves
RTM Image /w Smooth Velocity
![Page 18: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/18.jpg)
The Salt Model
• Model size: 601 x 601
• Source freq: 20 hz
• shots: 601
• geophones: 601
0 X (km) 6
0Z
(km
)6
![Page 19: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/19.jpg)
0Ti
me
(s)
10
0 X (km) 6
A Shot Gather of the Salt Model
![Page 20: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/20.jpg)
0 X (km) 6
0Z
(km
)6
0 X (km) 6
Migration Velocity
RTM with Smooth VelocityRTM Image
![Page 21: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/21.jpg)
RTM Image
0 X (km) 6
0Z
(km
)6
0 X (km) 6
Migration Velocity
If the Horizontal Reflectors are embedded in the velocity
![Page 22: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/22.jpg)
0 X (km) 60 X (km) 6
0Z
(km
)6
Migration Velocity
New Method
RTM Image
0Z
(km
)6
Prism Wave ImageConv. RTM Image
![Page 23: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/23.jpg)
0 X (km) 6
0Z
(km
)6
Migration Velocity
New Method
Filtered RTM Image
0Z
(km
)6 0 X (km) 6
Prism Wave Image
![Page 24: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/24.jpg)
Final Image
0 X (km) 6
Final Image
0 X (km) 6
0Z
(km
)6
Horizontal
Vertical
0Z
(km
)6
RTM Image
![Page 25: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/25.jpg)
Summary• I propose a new method to migrate prism waves
separately.
Limitations• Computational cost is doubled.
Avoid the modification of migration velocity.
Reduce cross interference between different waves by
migrating different waves in separated steps.
![Page 26: Reverse Time Migration of Prism Waves for Salt Flank Delineation](https://reader035.vdocuments.us/reader035/viewer/2022062810/56815e49550346895dccbfc4/html5/thumbnails/26.jpg)
Thanks