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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes


Chapter from: M 66:  Hydrocarbon Migration And Its Near-Surface Expression
Edited By 
Dietmar Schumacher and Michael A. Abrams

Hans G. Machel

Geochemistry, Generation, Migration

Published 1996 as part of Memoir 66
Copyright © 1996 The American Association of Petroleum Geologists.   All Rights Reserved.

Machel, H. G., 1996, Previous HitMagneticNext Hit contrasts as a result of hydrocarbon seepage and migration, in D. Schumacher and M. A. Abrams, eds., Hydrocarbon migration and its near-surface expression: AAPG Memoir 66, p. 99-109.
Chapter 8
Previous HitMagneticNext Hit Contrasts as a Result of Hydrocarbon Seepage and Migration
Hans G. Machel

Department of Earth and Atmospheric Sciences
University of Alberta
Edmonton, Canada




Seepage of hydrocarbons from traps and migration from source rocks result in hydrocarbon-contaminated plumes in ground and formation waters. Such plumes are characterized mainly by a marked reduction in the redox potential, causing the generation of Previous HitmagneticNext Hit ferrous iron oxides and sulfides and the destruction of ferric iron oxides. The resulting Previous HitmagneticNext Hit mineral assemblages can be predicted on the basis of thermodynamic criteria and microbiological processes. Moreover, these assemblages may result in positive, absent, or negative Previous HitmagneticNext Hit contrasts relative to the total magnetization prior to hydrocarbon invasion. Thermodynamic modeling further suggests that Previous HitmagneticNext Hit contrasts are more likely and tend to become more positive with depth and with closer proximity to the hydrocarbon source(s).

Previous HitMagneticNext Hit mineral assemblages and the resulting Previous HitmagneticNext Hit contrasts, such as those predicted here, have been documented from several hydrocarbon seepage environments at or near the land surface. Such Previous HitmagneticNext Hit contrasts can be used for hydrocarbon exploration in association with other surface exploration methods. Previous HitMagneticNext Hit exploration for hydrocarbons can also be conducted successfully on drill cores. Furthermore, migration pathways can be delineated by Previous HitmagneticNext Hit methods because migration from source to reservoir rocks may generate Previous HitmagneticTop mineral assemblages similar to those in seepage from traps.

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