AAPG Studies in Geology No. 48 / SEG Geophysical References
Series No. 11, Chapter 5: High-resolution Ground-magnetic (HRGM) and Radiometric Surveys for Hydrocarbon Exploration:
Six Case Histories in Western Canada, by Leonard A. LeSchack and David R. Van Alstine, Pages 67 -
156AAPG Studies in Geology No. 48 / SEG Geophysical References Series No. 11
Exploration Case Histories: Applications of Geochemistry, Magnetics, and Remote Sensing
Edited by Dietmar Schumacher and Leonard A. LeSchackCopyright © 2002 by The American Association of Petroleum Geologists and the
Society of Exploration Geophysicists. All rights reserved.
High-resolution Ground-magnetic (HRGM) and Radiometric Surveys for Hydrocarbon
Exploration: Six Case Histories in Western Canada
Leonard A. LeSchack
Calgary, Alberta, Canada
David R. Van Alstine
Applied Paleomagnetics, Inc.
Redmond, Washington, U.S.A.
In Western Canada, and probably elsewhere around the world, "magnetically enhanced
zones" above microseeping hydrocarbon reservoirs can exhibit distinctive magnetic
signatures that are characteristic of the reservoir. These distinctive magnetic signatures
have proven to be invaluable for hydrocarbon exploration, and we have achieved 85%
exploration success using ground-based magnetic and radiometric techniques in Western
Canada. Differences in timing and duration of microseepage and differences in composition
and pressure of the microseeping hydrocarbon gases from separate petroleum systems
probably control the magnetic mineralogy, magnetic grain-size distributions, magnetic
susceptibility, and natural remanent magnetization (NRM) directions in the magnetically
enhanced zones. Together, these differences can yield diagnostic "residual"
(remanent + induced) short-spatial-wavelength magnetic anomalies above different