Lunchbox Geophysics

Trick or Treat: A grab bag of shot migration enhancement goodies

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Mark Ng

Tuesday, October 21st, 2008 – 12:00 PM
Aquitaine Auditorium, +15 level of 540 - 5 Avenue SW

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LunchBox Geophysics is free! Simply bring your own lunch (refreshments provided) and enjoy.


The talk is about enhancing prestack wave equation migration (WEM) using a few easy 'plug-ins'. I will use shot domain WEM as a demonstration to illustrate that the algorithm efficiency can be effectively improved by 200% to 400% via incorporation of the newly developed 'time-shift' imaging condition plus a simple mapping function. Another upgrade trick deals with the inherent error which arises in the use of finite migration depth steps in the presence of surface topography: specifically, I show that the error can be minimized by an insertion of a simple split-step Fourier statics correction term in any generic extrapolator. The third enhancement trick deals with how one can optimally normalize the migrated traces for stacking where many find it is a challenge in the case of structural data. Such image control normalization scheme can be achieved by an automated process which computes the weighting factors based on subsurface illumination.


Mark Ng graduated with a B.Eng (Distinction) from Concordia University in 1981 and an M.Sc. from the University of Calgary in 1983, both in electrical engineering specialized in communication and signal processing. He worked in the R & D department at Sefel Geophysical from 1983 to 1985. After that time he was employed by Geo-X Systems Ltd. as a research Geophysicist in Calgary. In 1991, he was invited to teach in the University of Changsha, China for a year. After teaching, he returned to Geo-X where he worked until the processing department was taken over by Divestco Inc. in 2005. He has continued to work there since that time.

Two times Mark's SEG papers received honorable mention recognition: High resolution Radon transform in the t-x domain using 'intelligent' prioritization of the Gauss-Seidel estimation sequence, SP P3.4, ranked among the top 25 best papers presented at the 2004 SEG 74th Annual International Meeting, and Using time-shift imaging condition for seismic migration interpolation, SPMI P1.1, ranked among top 30 papers presented at the 2007 SEG 77th Annual International Meeting. Away from his technical research, he writes music and is a photographer.