Denver

Jan 30–31

The DISC (Distinguished Instructor Short Course) is put on by the Society of Exploration Geophysicists. Each year, they select an instructor to offer a course on a topic of current interest in geophysics. This year, Doug Oldenburg is the presenter and he giving the course on Geophysical Electromagnetics: Fundamentals and Applications (the first non-seismic DISC… ever!).

There are a number of firsts with DISC 2017, and one that we are particularly excited about is the introduction of the DISC Lab. In addition to the day-long DISC Course, we are holding an additional DISC Lab day meant to be a chance to connect with local geoscientists and chat about what the problems and applications that they are exploring. Our goal for the DISC Lab are two-fold: to capture and share problems related to EM that geoscientists are working on worldwide and to promote the growth of a community working on problems in electromagnetic geophysics.

DISC 2017 kicked off at the Colorado School of Mines on Monday! It was our first event in the experiment that is DISC 2017, and we are grateful to everyone who took part.

Day 1: DISC Course

We had 57 people attend from a variety of backgrounds; the largest groups represented included professionals and students working in hydrocarbons, water, and geotechnical applications. A substantial number of graduate and undergraduate and students attended, thanks in-part to sponsorship from Condor Consulting and Chinook Geoconsulting!

It was our first debut of the presentation: Geophysical Electromagnetics: Fundamentals and Applications. We covered the spectrum — Direct Current Resistivity, Fundamentals of Electromagnetics, Frequency Domain EM, Time Domain EM, Ground Penetrating Radar and Induced Polarization. It is a lot to cover in one day!

I felt like I got a semester-long class’s worth of information in one day. Much of the material was a useful review from a fresh perspective. Some was brand new, which was exciting!

Case histories are a cornerstone of this course, they provide context for the discussion of the fundamental principles of EM and demonstrate cases where EM has been applied successfully. For each of the EM methods discussed, a case history using that technique was presented. They included applications in mineral exploration (Mt. Isa), water (Bookpurnong, Kasted), hydrocarbons (Barents Sea), geothermal (Hengill), geologic mapping (Noranda), and rock glaciers (Furggwanghorn). These case histories are written up on EM GeoSci (or will be soon!). As we take the DISC around the world, we plan to grow the available case histories and tailor them in each presentation to those of local interest.

All of the course materials presented in Denver are available at http://disc2017.geosci.xyz/denver and a few more photos are available on instagram.

Currents being channeled through a conductive target in a grounded time domain electromagnetic experiment.

During the presentation, we tried a few new things this year, including using slack as an avenue for participants to ask questions throughout the day. SEOGI KANG and myself (Lindsey Heagy) were engaging with participants while Doug was presenting — it was a great way to be able to help address questions or confusion in real-time, as well promoting discussion and capturing some related problems of interest (including an example from Markus, using Marine Electrical Resistivity Imaging for methane hydrates).

Questions and conversations in slack during the presentation about the Mt. Isa Case History.

One of the other “firsts” in DISC 2017 is the distribution of apps — numerical simulations built in Jupyter Notebooks connected with images and widgets that allow you to play with Maxwell’s equations. Many of the images in the presentation slides are built from the apps, so participants can reproduce and further explore the material.

The apps are so innovative and I know that we will point many of our clients to geosci.xyz so that they can play with the parameters to better understand current density, the electric field and how it relates to the current we inject.
Seogi Kang demo’s the Harmonic Vertical Magnetic Dipole app. Can you reproduce the images shown in the Inductive Sources slides?

Discussions over the coffee and lunch breaks, brought up some interesting projects and potential applications of EM including:

  • mapping abandoned coal mines as they present a geo-hazard when constructing drill pads at the surface (of current interest for fracking operations)
  • mapping near surface weathered layer needed for static corrections in seismic reflection surveys
  • estimating distribution and thickness of permafrost
  • locating low temperature geothermal resources in complex geologic settings using Magnetotellurics
Conversations at the end of the day.

Day 2: DISC Lab

DISC lab was designed to be more interactive and conversational. We started off with a round of lightning talks, 5 min a piece (+ questions and discussion… we got excited). The lightning talks are available on youtube. Following the lightning talks, we continued conversations and worked to break down and describe the problems that were presented in terms of a 7 step framework. Here is a summary of the people and problems they are working on:

  • Seogi Kang (slides, seven steps): Airborne Induced Polarization and an application to the TKC kimberlite deposit in Canada. How do you obtain polarization information from airborne EM data?
  • Paul Bedrosian (slides, seven steps): use of electromagnetics to unravel the complexities of 3D geologic environments. When are 3D inversions needed?
  • Jiajia Sun: Joint geophysical inversions. How do we integrate multiple methods to inform our interpretations?
  • John Hinton: Identify fractures, faults, karsts, and debris before intercepting with a Tunnel Boring Machines (TBM). How can GPR be used to look ahead of a TBM?
  • Brett Kravitz: Evaluating grout integrity in tunnels. How can GPR be used to non0invasively look for voids or flaws in the grout which seals the tunnel?
  • Ben Bloss (slides, seven steps): Power-line contamination in TDEM data. How do we understand and eliminate the effects of power-line contamination in airborne time domain EM data?
  • Roy Mink (seven steps): Low temperature geothermal exploration. How do we use Magnetotelluric data to characterize a low temperature geothermal system in a complex geology?
  • Brian James: interested in novel ways in imaging conductivity structures with electromagnetic data.
  • Andrei Swidinsky (slides, seven steps): Applications of marine EM including Mud Volcanoes and Gas Hydrates and dealing with the complexities of multi-component EM data measured on the ocean floor.
  • Joe Capriotti (seven steps): Reservoir monitoring using time-lapse gravity data. What role could EM play? Also… how to build geologic models of the world using Minecraft.
  • Roxana Safipour (slides, seven steps): New techniques for marine EM surveys. How do we use inductive source EM to explore for submarine massive sulfides?
  • Anna Kelbert (seven steps): simulating electromagnetic fields to assess the hazard posed by geomagnetic storms on the power grid. How do we estimate large-scale conductivity structures of the earth from data sets such as Earth Scope? What impact do regional conductivity structures have on how much current can be channeled into the power grid?
  • Max Mifkovic (seven steps): using DC resistivity to look ahead of Tunnel Boring Machines. How do we design a DC resistivity experiment that is sensitive to structures (voids, wood debris, changes in geology,…) in front of a TBM?
Powerlines + airborne EM data.

We wrapped up the day with discussion on a few avenues for moving forward together, including collaborating on computational resources (SimPEG), as well as capturing case histories and technical material through EM GeoSci.

DISC Lab — working hard to break-down problems into seven steps

Acknowledgements

Such an event never would have happened without the support of local participants to help organize logistics and encourage people to participate. In particular, Yaoguo Li, Misac Nabighian, Michelle Szobody, Andrei Swidinsky, Kamini Singha, Jeff Love, Karen Christopherson, Liz Maag, Andy McAiley, Joe Capriotti and the CGEM group.