- The document describes a new imaging workflow called eGWM that uses a one-way wave equation algorithm to output pre-stack image gathers from wave equation migration. - eGWM pre-stack gathers can be used for AVO and pre-stack inversion analysis to robustly understand amplitudes and reduce drilling risk in complex areas like below salt or basalt. - eGWM fully preserves amplitudes through multi-path and multi-arrival imaging, making quantitative amplitude analysis achievable in complex areas.

1. eGWM
AVO Analysis comparison
Elastic Synthetic Model
November 2018

2. eGWM – A breakthrough in outputting pre-stack image
gathers from Wave Equation migration
• A new imaging workflow with One-Way Wave equation algorithm by outputting
offset and angle gathers using dual domain imaging condition.
• The eGWM pre-stack gathers which can be used for AVO and Pre-Stack Inversion
analysis give a robust understanding of the amplitudes and thus significantly reduce
drilling risk around complex bodies.
• eGWM does multi-path & multi arrivals to fully preserve amplitudes. This makes
quantitative amplitude analysis in complex areas a reality – Sub-Salt and Sub-Basalt
achievable.
• Advantages of eGWM technology;
• 0 to Nyquist frequency at linear run time with frequency. RTM is quadrature with frequency!
• 20 times faster than RTM to output stack Image
• 50 times faster than RTM to output gathers
admin@seismicimageprocessing.com http://www.seismicimageprocessing.com/

3. Elastic wavefields shown in this slide are used to generate
synthetic seismic data
Pwave Swave density
Fluid response
Fluid response

4. Shots and CMPS generated from the from synthetic
wavefield shown on previous slide
Unmigrated SHOTS Unmigrated CMPS
These shot and CMP gathers have been imaged using both Kirchhoff and eGWM as shown in the
following slide.

5. Depth Migrated CDP offset gathers
eGWM Kirchhoff
Polarity reversal at Base
Class-3 at Top

6. eGWM angle gathers 0-30deg in time Kirchhoff angle gathers 0-30deg in time
CDP Location
AVO Response
Class-3 at Top
Class-2P at Base

7. Velocity model in Time eGWM angle gathers Stack 0-30deg in time

8. Velocity model in Time Kirchhoff angle gathers Stack 0-30deg in Time

9. eGWM angle gathers Stack
0-15deg in Time
eGWM angle gathers Stack
15-30deg in Time
eGWM angle gathers Stack
30-45deg in Time
Polarity reversal at base
Correct AVO (No Leakage in the grabens
And structure below is better amplitude image

10. Kirchhoff angle gathers Stack
0-15deg in Time
Kirchhoff angle gathers Stack
15-30deg in Time
Kirchhoff angle gathers Stack
30-45deg in Time
Polarity reversal at base
FALSE AVO (Leakage in the grabens
And below is poorly imaged

11. eGWM angle gathers 0-30deg- Fluid Factor in depth Kirchhoff angle gathers 0-30deg- Fluid Factor in depth
Seismic Image processing Ltd is offering eGWM solutions to many clients across the Globe. Any questions and clarifications please send
an email to admin@seismicimageprocessing.com; Jagat.deo@seismicimageprocessing.com; Please visit our website:
http://www.seismicimageprocessing.com/
smearing of the amplitudes

12. SIP eGWM (50Hz) vs RTM (50Hz)
RTM 50Hz Image eGWM 50Hz Image
Input:
• Industry standard RTM used to run 50Hz
• Input – processed shot gathers
• Input maximum offset – 10km
• Aperture used- 20km full aperture
Observations:
• Generates noise at the interface of large velocity contrast top/base salt
• Require more time to complete one Iteration of RTM
• Doesn’t honour true amplitudes
• Expensive to output gathers and not practical
Input:
• SIP eGWM used to run 50Hz
• Input – processed shot gathers
• Input maximum offset – 10km
• Aperture used- 20km full aperture
Observations:
• Noise free compared to RTM, due to implementation of absorbing boundary conditions
• Honours true amplitudes
• Output offset and angle gathers simultaneously
• Gathers at a fraction of the cost of RTM