Dear Colleagues:
Next week the early registration discount for the two Short Courses in front
of the Calgary SEG expires (July 5th). Yaoguo Li has provided the attached
note outlining the highlights of the inversion workshop and rumor is that
Richard Smith will be showing some 'hot' MEGATEM data over the OGS's
Reid-Mahaffey test range in his short course.
Look forward to seeing you in Calgary!
Regards
Ken Witherly
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This is a friendly reminder about this year's special
presentation short course "Inversion of DC resistivity,
IP and Magnetic Data for Mineral Exploration" presented
by Doug Oldenburg and Yaoguo Li.
The course deals with the application of geophysical
inverse theory to exploration problems. Materials are
based on two successful workshops presented in Vancouver.
This will be an excellent course for anyone who would
like to learn more about quantitative interpretation
techniques beyond simple examination of data plots.
The July 10 deadline for advanced registration (at reduced
rate) is approaching. I encourage those who are interested
to sign up as early as you can.
Attached below is the description of the short course.
Background information about the instructors can be found
at the SEG Continuing Education webpage.
===========================================================
Special Presentation by the Mining and Geothermal Geophysics Committee....
Inversion of DC resistivity, IP and Magnetic Data for Mineral Exploration
Doug Oldenburg, Yaoguo Li
Duration: one day
August 5, 2000
The recent introduction of rigorous methods for inverting
geophysical data has created a demand for increasingly
quantitative interpretations of subsurface physical
property distributions. In this one-day course we show how
DC resistivity, IP and magnetic data can be inverted to
recover two- and three-dimensional images of subsurface
properties. The emphasis is on understanding the fundamentals
of inversion procedures and showing how to obtain good
inversions of practical field data sets. Case histories
from mineral exploration data sets will be used throughout
the workshop to illustrate the application of inversion
techniques to practical problems. Mathematical details are
kept to a minimum. The first portion of the day is devoted
to discussing basic elements of geophysical inversion. The
realities of non-uniqueness are confronted by investigating
the two fundamental questions of inversion: "What type of
model do I want to construct?" and "How well should I fit
the data?" This understanding is essential for those
geoscientists carrying out the inversions and for those
who are making geologic interpretations of the images.
A major portion of the day focuses upon specific aspects
that are required to invert practical data sets acquired
in DC/IP and magnetic surveys. Notes, examples and other
educational material will be provided on CD-ROM.
Course Outline
1. Examples of data and inversion results
(1) Why inversion is needed
(2) Linear inverse theory.
(3) Data, model, kernels.
(4) Casting the inverse problem as an optimization problem.
(5) Designing the model objective function and data misfit.
(6) Solving the problem.
2. 3-D magnetic inversion.
(1) Background on magnetic surveys.
(2) What are the data and how they relate to magnetic susceptibility.
(3) It seems like a linear inverse problem, but there is a fundamental
difficulty with non-uniqueness.
(4) The crucial importance of a depth weighting in the objective
function and positivity.
(5) Synthetic and fields examples. Real-time demos of the inversion.
3. Basics of non-linear inversion.
(1) 2-D inversion of DC resistivity and IP data.
(2) Synthetic examples. Field data examples and practical
issues of inverting field data. Real-time demos of the inversion.
4. Case Histories for Mineral Exploration
Course Tuition: (members/non-members)
$155/225
$190/260 (if received after July 5)
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