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2017 Distinguished Instructor
Short Course | Doug Oldenburg
Geophysical Electromagnetics: Fundamentals and Applications

Overview
Electromagnetics has applications in oil and gas exploration andproduction, mineral exploration, groundwater exploration andmonitoring, geotechnical, and environmental industries. Although
it has widespread applications as a geophysical technique, it is not
generally understood by the geoscience community. As a result it isunderutilized, and in some cases, misused, as a technology.
The aim of this course is to provide a fundamental understanding
about EM geophysics so that practitioners can decide if an EMtechnique can help solve their problem, select which type of survey
to employ, and set realistic expectations for what information canbe gleaned. Case histories, spanning applications from many areasin the geosciences, are used as an underlying framework to bind thematerial together.
Content: Fundamentals and Applications
Case histories pertain to problems in resource exploration, including
oil and gas, minerals, water, environmental, and geotechnical areas
and are contributed by experts worldwide.
These include:• resource detection (e.g. methane hydrates) or de-risking (e.g.
offshore-hydrocarbons),• imaging SAGD steam chambers or monitoring hydraulicfracturing,•m ineral exploration (on land, on the ocean floor sea floor massivesulfides),•w
 ater issues (e.g. monitoring salt water intrusion, imagingaquifers),

SM

Connecting the World of Applied Geophysics• imaging geothermal systems,• d etecting and discriminating unexploded ordnance,• g eotechnical characterization, including slope stability
We use these applications as motivation for investigatingfundamentals of electromagnetics. We successively look atapplications that make use of:• S teady state fields (e.g. DC resistivity, induced polarization)• F requency domain EM (e.g. marine CSEM, airborne surveys)• T ime domain EM (e.g. airborne, ground, borehole surveys)• N atural source EM (e.g. Magnetotellurics, Z-Axis Tipper /ZTEM)
The energy sources for these surveys can be man-made or
natural. Man-made sources include inductive transmitters (loopsof wire carrying a current) or galvanic sources where current isinjected into the ground. The natural energy sources promote
MT (magnetotellurics), which is important for characterizing
deep conductivity structures for geothermal energy, and ZTEM,
which has proven to be valuable in geologic mapping and mineral
exploration. The various surveys can be carried out in the air using
helicopters or airplanes, on the earth’s surface, or underground; thegeoscientific question to be addressed determines which survey isselected. Case histories and survey types presented will be tailoredto each location at which the DISC is presented, and chosen basedon the local problems of general interest.

seg.org/DISC

2017 Distinguished Instructor Short Course — Doug Oldenburg | Geophysical Electromagnetics: Fundamentals and Applications
DISC 2017
Electromagnetics has applications across oil and gas explorationand production, mineral exploration, groundwater exploration andmonitoring, geotechnical, and environmental industries. Although
it has widespread applications as a geophysical technique, it
is not generally understood by the geoscience community. As
a result it is underutilized, and in some cases, misused, as atechnology.
The goal of the 2017 DISC is to provide fundamental
understanding about EM geophysics so that practitioners candecide if an EM technique can help solve their problem, selectwhich type of survey to employ, and set realistic expectations
for what information can be gleaned. Case histories, spanningapplications from many areas in the geosciences, are used as anunderlying framework to bind the material together.
Each case history is presented in a seven-step process thatbegins with the description of the geologic or geophysicalproblem to be solved and ends with the impact of the EM
geophysical survey to help solve the problem. At points in themiddle, we investigate the details of the particular EM survey,
some fundamentals of electromagnetic induction, and techniques
for processing/inverting the data. The ability to move seamlessly
between these different levels of information, so that relevant
questions or concepts can be addressed, is facilitated by new
open-source numerical software, interactive simulations, andthe “textbook” resource http://em.geosci.xyz. Although wework continually with Maxwell’s electromagnetic equations, thepresentations are mathematically “light” and the learning aspect
is facilitated by the use of Jupyter notebooks, and visual aides.
The case histories pertain to problems in resource exploration(oil and gas, minerals, water), environmental, and geotechnicalareas, and are contributed by experts worldwide. We successively
look at surveys that make use of steady state fields (e.g. DC
resistivity, induced polarization) and then move on to frequency
and time domain EM. The energy sources for these surveys
can be man-made or natural. Man-made sources include
inductive transmitters (loops of wire carrying a current) orgalvanic sources where current is injected into the ground. The

natural energy sources promote MT (magnetotellurics), which
is important for characterizing deep conductivity structures forgeothermal energy and ZTEM (Z-Axis Tipper EM), and has provento be valuable in geologic mapping and mineral exploration. The
various surveys can be carried out in the air using helicopters orairplanes, on the earth’s surface, or underground, and the casehistory determines which survey is selected. The choice of casehistories and surveys to focus on depends upon the location atwhich the DISC is presented and the local problems that are ofgeneral interest. Prior to any presentation we are soliciting locallygenerated case histories.
The 2017 DISC is designed to be of interest to a broad audience,
including researchers, practitioners, and industry geoscientists,
and accessible to those with little background in EM. It is
not possible to cover all of EM geophysics in a single day but
attendees will obtain new insight about EM fundamentals andapplications. The DISC material, and the associated open source
resources, can then act as a catalyst to develop a communitythat can share information, interact on EM problems of mutualinterest, and elevate the use of EM geophysics to solve appliedproblems.
Who should attend?
Geophysicists and any geoscientists who have the potential
to use, or be associated with, electromagnetic data. The 2017
DISC is designed to be of interest to a broad audience, including
researchers, practitioners, and industry geoscientists, andaccessible to those with little background in EM.

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