Mark E. Willis

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Mark E. Willis
BSc Applied Math and Physics
PhD Geophysics
BSc university University of Wisconsin – Milwaukee
PhD university MIT

Mark E. Willis is the Chief Scientific Advisor of Borehole Seismics at Halliburton. He is responsible for mentoring technologists, developing and promoting geophysical innovations, and fostering long-term client relationships. Prior to joining Halliburton in 2011, he worked in various research technology, supervisory and management positions at Mobil Oil, Cambridge GeoSciences, Massachusetts Institute of Technology Earth Resources Laboratory, and ConocoPhillips.

In his career, Mark has performed research and development in distributed acoustic sensing, VSP technology, deep sonic log imaging, fracture identification using seismic data (time lapse VSP, microseismics, and surface seismic scattering), interferometric imaging, Kirchhoff and reverse time depth migration, full waveform inversion, machine learning, velocity model building, and sonic waveform processing.

Mark holds a B.S. in Applied Math and Physics from the University of Wisconsin – Milwaukee and a Ph.D. in Geophysics from MIT. He has written more than 100 papers, publications, and presentations, and holds multiple patents. He is a member of the SEG, EAGE, SSA, SPWLA, and ASA.

2022–2023 SEG Distinguished Instructor Short Course

Distributed acoustic sensing for seismic measurements – what geophysicists and engineers need to know

Geoscientists and engineers are very comfortable using seismic data sets acquired with geophones, hydrophones, and accelerometers because we have a long, well-defined set of standards for acquiring, processing, and interpreting them. However, distributed acoustic sensing (DAS) seismic measurements are rapidly augmenting, and in some cases replacing, the data from these conventional tools. Technologists are frequently unaccustomed to using DAS seismic data sets since it directly acquires relative strain or strain rate measurements and not the more familiar pressure, displacement, velocity, and acceleration data. There are also acquisition parameter selections that must be made to optimize the acquired data to accomplish the purpose of the seismic survey. This course is designed to build an intuition and understanding of the value, limitations, and applications of DAS seismic technology. In addition to the lecture and accompanying book, software will be provided, which will allow the student to interactively explore DAS seismic technology.

This course will coverː

  • What are many of the applications for DAS technology?
  • How do conventional and DAS seismic measurement systems compare?
  • How can we convert between DAS and geophone measurements?
  • What is the physics behind DAS measurements and the composition of optical fiber? Do different types of fiber optic cables offer advantages?
  • How is a DAS acquisition system architected? How does the fiber optic cable deployment method affect the DAS measurements?
  • What is the gauge length and how does it affect the acquired data? How does the pulse width interact with the gauge length to improve data quality?
  • What is the angular response of the fiber optic cable to incoming seismic signals? How does the angular response of the fiber affect VSP, surface seismic, and microseismic measurements?
  • What are the sources of DAS noise and how are they mitigated? Can we remove the effects of poor fiber optic cable coupling from the seismic data?
  • How can we plan and prepare for a DAS seismic survey? What are the key decisions that need to be made and can we model them?
  • What are the field deployment issues that we should address? How is handling fiber optic cables different from standard electrical cables? Can the health of the deployed fiber be determined before the survey begins? How is the depth (or distance along the fiber) of each channel of seismic data determined?

Course Goals

The goal of this course is to create a basic intuition for the value of DAS seismic measurements as well as the acquisition and processing decisions that affect its quality. The ever-present trade-offs will be discussed between resolution and signal to noise ratio. The limitation of one component measurements will be countered by the advantage of spatially dense sampling. After taking this course, it will be easier for the technologist to decide whether to acquire seismic data using DAS, as well as how to choose optimum acquisition and processing parameters.

Additional Resources

The accompanying textbook is available for purchase.[1]

Listen to Mark discuss his lecture in What geophysicists and engineers need to know about DAS, Episode 158[2] of Seismic Soundoff, in-depth conversations in applied geophysics.


External links

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Mark E. Willis
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