Life in the slow lane; biogeochemistry of biodegraded petroleum containing reservoirs and implications for energy recovery and carbon management

Abstract

Our understanding of the processes underlying the formation of heavy oil has been transformed in the last decade. The process was once thought to be driven by oxygen delivered to deep petroleum reservoirs by meteoric water. This paradigm has been replaced by a view that the process is anaerobic and frequently associated with methanogenic hydrocarbon degradation. The thermal history of a reservoir exerts a fundamental control on the occurrence of biodegraded petroleum, and microbial activity is focused at the base of the oil column in the oil water transition zone, that represents a hotspot in the petroleum reservoir biome. Here we present a synthesis of new and existing microbiological, geochemical, and biogeochemical data that expands our view of the processes that regulate deep life in petroleum reservoir ecosystems and highlights interactions of a range of biotic and abiotic factors that determine whether petroleum is likely to be biodegraded in situ, with important consequences for oil exploration and production. Specifically we propose that the salinity of reservoir formation waters exerts a key control on the occurrence of biodegraded heavy oil reservoirs and introduce the concept of palaeopickling. We also evaluate the interaction between temperature and salinity to explain the occurrence of non-degraded oil in reservoirs where the temperature has not reached the 80–90°C required for palaeopasteurization. In addition we evaluate several hypotheses that might explain the occurrence of organisms conventionally considered to be aerobic, in nominally anoxic petroleum reservoir habitats. Finally we discuss the role of microbial processes for energy recovery as we make the transition from fossil fuel reliance, and how these fit within the broader socioeconomic landscape of energy futures.

Methanogenic Hydrocarbon Degradation: Evidence from Field and Laboratory Studies

“…The composition of these hydrocarbon-degrading microbial communities seems to be determined by the availability of electron acceptors [Head et al, 2014]. Many of the phylotypes iden-tified in methanogenic hydrocarbon-degrading microbial communities from a variety of habitats are similar.…”

“…Gippsland and Otway Basins Pallasser, 2000 Dryness, low percentages of C 2 + hydrocarbons (<2%) Dagang oil field, Western Siberian Basin Head et al, 2014;Jiménez et al, 2012;Milkov, 2010Milkov, , 2011 Relationship between C 1 /(C 2 + C 3 ) and δ 13 C-CH 4…”

“…Acetotrophic and acetogenic Arcobacter species, together with fermenters belonging to Sulfurospirillum, have often been detected in oil reservoirs or coal deposits, such as coalbearing sediments from the Ruhr area [Gründger et al, 2015], the Waikato Basin in New Zealand [Fry et al, 2009] or the Pelican Lake oil reservoir in Alberta, Canada [Grabowski et al, 2005a, b], among many others [Gray et al, 2010;Head et al, 2014;Hubert et al, 2012].…”

FITORREMEDIACIÓN DE UN SUELO CONTAMINADO CON PETRÓLEO EXTRA PESADO CON Megathyrsus maximus

“…Adicionalmente, aún cuando la toxicidad de los petróleos pesados y extra pesados suele ser menor, existe un efecto físico sobre las propiedades del suelo, como es la disminución de la capacidad de campo e incremento de la repelencia al agua, entre otras propiedades, que merman su fertilidad (Adams et al 2008). Cabe destacar que el bitumen y los hidrocarburos pesados constituyen las mayores reservas de petróleo del mundo (Head et al 2014), hecho que justifica la investigación sobre la rehabilitación de suelos contaminados por este tipo de hidrocarburos.…”

“…Adicionalmente, aún cuando la toxicidad de los petróleos pesados y extra pesados suele ser menor, existe un efecto físico sobre las propiedades del suelo, como es la disminución de la capacidad de campo e incremento de la repelencia al agua, entre otras propiedades, que merman su fertilidad (Adams et al 2008). Cabe destacar que el bitumen y los hidrocarburos pesados constituyen las mayores reservas de petróleo del mundo (Head et al 2014), hecho que justifica la investigación sobre la rehabilitación de suelos contaminados por este tipo de hidrocarburos.Dentro de las técnicas para la descontaminación de suelos, la fitorremediación resulta atractiva por su bajo costo, por mejorar las condiciones del suelo, por ser estéticamente agradable y ambientalmente amigable (Pilon 2005, Yavari et al 2015. La fitorremediación se fundamenta en el uso de plantas y su microbiota asociada para remover, retener o reducir los contaminantes presentes en el ambiente y puede operar mediante diversos mecanismos que involucran distintas partes de las plantas (Chávez-Maldonado et al 2010, Khan et al 2013.…”