Book contents
- Frontmatter
- Contents
- About the authors
- Preface
- Purpose
- Acknowledgments
- PART II BIOMARKERS AND ISOTOPES IN PETROLEUM SYSTEMS AND EARTH HISTORY
- 12 Geochemical correlation and chemometrics
- 13 Source- and age-related biomarker parameters
- 14 Maturity-related biomarker parameters
- 15 Non-biomarker maturity parameters
- 16 Biodegradation parameters
- 17 Tectonic and biotic history of the Earth
- 18 Petroleum systems through time
- 19 Problem areas and further work
- Appendix: geologic time charts
- Glossary
- References
- Index
16 - Biodegradation parameters
Published online by Cambridge University Press: 05 April 2013
- Frontmatter
- Contents
- About the authors
- Preface
- Purpose
- Acknowledgments
- PART II BIOMARKERS AND ISOTOPES IN PETROLEUM SYSTEMS AND EARTH HISTORY
- 12 Geochemical correlation and chemometrics
- 13 Source- and age-related biomarker parameters
- 14 Maturity-related biomarker parameters
- 15 Non-biomarker maturity parameters
- 16 Biodegradation parameters
- 17 Tectonic and biotic history of the Earth
- 18 Petroleum systems through time
- 19 Problem areas and further work
- Appendix: geologic time charts
- Glossary
- References
- Index
Summary
This chapter explains how biomarker and non-biomarker analyses are used to monitor the extent of biodegradation. Compound classes and parameters are discussed in the approximate order of increasing resistance to biodegradation. The discussion covers recent advances in our understanding of the controls and mechanisms of petroleum biodegradation and the relative significance of aerobic versus anaerobic degradation in both surface and subsurface environments. Examples show how to predict the original physical properties of crude oils before biodegradation.
Petroleum biodegradation is the alteration of crude oil by living organisms (e.g. Milner et al., 1977; Connan, 1984; Palmer, 1993; Blanc and Connan, 1994). Numerous eubacteria, fungi, and possibly archaea evolved metabolic pathways to consume saturated and aromatic hydrocarbons. The existence of these pathways in ancient and diverse prokaryotic lineages provides indirect evidence that petroleum systems occurred during the early Precambrian Age. Petroleum biodegradation is primarily a hydrocarbon oxidation process, producing CO2 and partially oxidized species, such as organic acids. Heteroatomic compounds are less susceptible to biological attack and increase in relative abundance as biodegradation proceeds. This increase is caused primarily by enrichment of pre-existing petroleum NSO compounds due to selective biodegradation of other compounds, but a secondary cause is the direct production of heteroatomic compounds (mainly oxidized species) by microbes. Petroleum quality and net volume thus decrease with increasing biodegradation. API gravity decreases while non-hydrocarbon gases, viscosity, NSO compounds, and trace metals increase.
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- Information
- The Biomarker Guide , pp. 645 - 708Publisher: Cambridge University PressPrint publication year: 2004
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