The State and future Directions of Prestack Depth Migration


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2011 SEG Honorary Lecturer Latin America. Prestack depth migration (PSDM) has undergone tremendous evolution over the past 20 years. In order to better understand the subsurface, it is crucial to obtain seismic depth images with the appropriate definition and resolution that will allow us to reduce the geological uncertainty for oil exploration and well placement.

This has been primarily due to the evolution of three key constitutive parts, namely:

  • the migration algorithms,
  • velocity-model building workflows,
  • high-performance computing technology,
  • and more effective synergy between processing analysts, geophysicists, and geologists-interpreters.

Widespread implementation of more sophisticated and effective geophysical algorithms and processes (like reverse time migration, anisotropy, wide-azimuth data acquisition and imaging, tomographic inversion, 3D free-surface multiple elimination) have permitted practical solutions to a wide range of subsurface imaging problems involving complex geology in general, and salt tectonics in particular.

The above could not be possible in practice without the tremendous increase in and adoption of high- performance computer technology. Probably because of the videogame industry, powerful processing power is available at very reasonable prices, in the form of advanced multicore processors and graphics cards, complemented with massive amounts of cheap disk space and fast hardware-interconnect technologies. However, the best migration algorithms and fastest computers do not mean much without the most crucial ingredient of all: namely, the focused and effective cross-discipline work between geophysicists, analysts, and geologists.

This presentation reviews the evolution of PSDM to its present state, looks at its geophysical fundamentals, frames PSDM within the development of high-performance computing, stresses the emphasis of people interaction, and illustrates how it has helped us to solve subsurface imaging problems.

I conclude the talk with my forecast of some future directions for PSDM, like full waveform inversion, wave-equation-based tomography, elastic PSDM and other "hot" topics from the current literature. I will assess what we may see in computer technology as related to PSDM.

As this talk is oriented to geoscience students and practicing geologists/geophysicists in Latin America, the central focus of PSDM is guided by the author's practical experience in Mexico, where the problems are not necessarily the same as elsewhere. I hope to offer the audience an additional motivation and viewpoint about PSDM as applied in the oil industry.

Your Instructor

Julian Cabrera, PhD, SEG-HL
Julian Cabrera, PhD, SEG-HL

Julian Cabrera graduated from the National Polytechnic Institute, Mexico City, with a degree in engineering geophysics in 1981. He completed his M.Sc. and Ph.D. degrees in geophysics in 1984 and 1989, respectively, both from the University of British Columbia, Canada. His research area was depth imaging.

Dr. Cabrera has worked in Mexico, Canada, Venezuela and the USA. He partnered in a start-up company, Inverse Theory and Applications (1984-1990), and worked for Tensor Geophysical (1990-1993) and Western Geophysical (1993-1996), as a key researcher, software developer, and data processing troubleshooter. From 1996 to 2002, he lived and worked in Caracas, Venezuela, as a senior geophysical advisor for PDVSA.

In 2003, he returned to the USA, set up his own consulting firm, Seistech Consulting LLC, and began consulting for Pemex E&P. He currently oversees depth imaging projects for Pemex E&P at processing service companies located in Houston, Texas. He has also consulted for TGS Imaging, Fugro Seismic Imaging, and Compania Mexicana de Exploraciones.

Dr. Cabrera's main professional expertise in seismic imaging has involved R&D, programming high-performance computers, processing and project supervision, and QC. He has been deeply involved in 3D depth imaging since its early days (1990) in the industry.