Anaerobic hydrocarbon biodegradation in deep subsurface oil reservoirs

Abstract

Biodegradation of crude oil in subsurface petroleum reservoirs is an important alteration process with major economic consequences. Aerobic degradation of petroleum hydrocarbons at the surface is well documented and it has long been thought that the flow of oxygen- and nutrient-bearing meteoric waters into reservoirs was necessary for in-reservoir petroleum biodegradation. The occurrence of biodegraded oils in reservoirs where aerobic conditions are unlikely, together with the identification of several anaerobic microorganisms in oil fields and the discovery of anaerobic hydrocarbon biodegradation mechanisms, suggests that anaerobic degradation processes could also be responsible. The extent of anaerobic hydrocarbon degradation processes in the world's deep petroleum reservoirs, however, remains strongly contested. Moreover, no organism has yet been isolated that has been shown to degrade hydrocarbons under the conditions found in deep petroleum reservoirs. Here we report the isolation of metabolites indicative of anaerobic hydrocarbon degradation from a large fraction of 77 degraded oil samples from both marine and lacustrine sources from around the world, including the volumetrically important Canadian tar sands. Our results therefore suggest that anaerobic hydrocarbon degradation is a common process in biodegraded subsurface oil reservoirs.

How sulphate-reducing microorganisms cope with stress: lessons from systems biology

“…More recently, GeoChip has been used to investigate microbial responses to the oil spill in the Gulf of Mexico 112 . SRM populations were found to be considerably larger in the oil-contaminated samples than in non-contaminated samples (Z. Lu and J.Z., unpublished observations), suggesting that these organisms contribute to natural bioremediation of oilcontaminated deep-sea ecosystems, as indicated by previous studies [117][118][119][120] . These and other applications of GeoChip 109,[121][122][123][124] demonstrate that this is a powerful tool for detecting and monitoring SRM populations and their associated microbial communities, as well as for assessing their metabolic potential and activity in response to different environmental stresses.…”

Thermodynamic constraints on methanogenic crude oil biodegradation

“…It is responsible for the in-reservoir degradation of oil that has lead to vast heavy oil and tar sand deposits that constitute the bulk of the world's petroleum inventory (Roadifer, 1987;Head et al, 2003;Aitken et al, 2004). Despite the importance of the process, relatively little is known about the Figure 7 Effect of temperature on the range of H 2 partial pressures where both incomplete oxidation of hexadecane to acetate and H 2 and methanogenic CO 2 reduction are exergonic.…”

“…Reduced naphthoic acids, metabolites characteristic of anaerobic hydrocarbon degradation have been detected in biodegraded petroleum reservoirs, but not in nondegraded reservoirs (Aitken et al, 2004). Geochemical and isotopic evidence also suggests that in many cases the end product of hydrocarbon degradation in petroleum reservoirs is methane (Scott et al, 1994;Larter et al, 1999;Sweeney and Taylor, 1999;Pallasser, 2000;Boreham et al, 2001;Masterson et al, 2001).…”

Distribution of acids and nitrogen-containing compounds in biodegraded oils of the Liaohe Basin by negative ion ESI FT-ICR MS

“…Anaerobic biodegradation of crude oil is a common phenomenon occurring in subsurface oil reservoirs (Aitken et al, 2004). It is widely accepted that microbial degradation significantly alters the molecular composition and physical properties of crude oil, leading to a decrease in low molecular weight saturates and aromatics and an increase in polars, oil density, viscosity, sulfur content and acidity (Evans et al, 1971;Connan, 1984;Meredith et al, 2000;Peters et al, 2005).…”