Electro-Magnetic or EM Techniques & Surveys have been around for decades now and most explorationist's will have limited exposure to one or more of them. Such EM techniques include land magneto-tellurics MT, audio MT, marine MT and now Controlled Source EM - CSEM. The first three have been successful commercial exploration tools for some time now and are very good for answering regional geological questions in areas where seismic fails or is ambiguous...areas such as sub-salt, sub-volcanics sub-carbonates...ie poor seismic regions. The EM methods help the explorationist by measuring the passive electrical energy flow in the earth which allows for identification of regional conductor and resistor rocks.

However the new CSEM technique that is getting the recent strong attention is rather different. Although it uses similar receiver technology to the passive method it then couples it with an active dipole EM source. Thus CSEM offers an entirely new set of applications for EM by its ability to image much thinner resistors down to 10's of meters rather than the 100's of meters of passive EM.

CSEM has been effectively proven over the last 3 years as an exceptional new geophysical tool that can and already is changing the way companies work in exploration, appraisal and development.

Of CSEM the CEO of a major US Oil Corporation recently stated something like :

"Research in non-seismic electro-magnetic hydrocarbon detection has led to new technology for remotely detecting and imaging hydrocarbons from the earth's surface. This new technology "CSEM" holds great promise for accurately assessing potential hydrocarbon resources and reducing exploration risk"

....and others have described the technology as the most significant new E & P development since the transition from analog to digital...cdp stacking, 3D....and more recently DHI's and AVO.

This talk describes how to plan and carry out a successful CSEM survey.

"How to Plan for a Successful CSEM Survey"
Contents :

  • Introduction - EM can be a Life Changing Experience !

  • So You Really Want to do a CSEM Survey ?

  • Some Critical Things To Consider About Your Prospect

  • Survey Layout and Design

  • Processing and Interpretation of Results

  • Summary...and Good Luck

A, Introduction

To all of you geologists and geophysicists used to working with seismic and now about to read this paper, please be aware that getting involved with EM surveys may be a life changing experience...you may never be the same again, so consider yourself warned. I just don't want you blaming me later on for not telling you upfront.

You see I used to be a "normal" seismic guy happily doing my usual seismic geophysics and geology and exploring until 1990... then someone asked me to do an EM survey...and life has somehow never ever been quite the same since.

This is not a hard complicated paper...in fact just the opposite, what we have tried to do in our 20 minutes is to condense some 30 years of hard won EM experience into a few basic guidelines to help you with your first CSEM survey.

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