Metagenomics a Novel Technology to be used for Prospecting Unconventional Petroleum Resources in the Barents Sea

Anne Rike

The Barents Sea is characterized as a frontier area due to knowledge gaps in the geology, little infrastructure and significant technical challenges in connection with climatic conditions. In addition to the conventional resources the area may contain presently unknown volumes of unconventional petroleum resources such as gas hydrates and shale gas. We will here describe how metagenomics can supplement prospecting during early phases of exploration. Our experience is gained from hydrocarbon seeps and prospecting for conventional resources, but the technology can also be used for future prospecting for gas hydrates and marine shale gas. Metagenomics is the study of the genetic content (DNA), independent of organisms and cultivation, in a complex sample such as marine sediments. The composition of a microbial consortium in a sample and the genes is influenced by the environmental conditions at a site. All hydrocarbon resources are, to some extent, leaking over time. Flow rates of methane even down to the level of diffusion are probably sufficient to sustain the existence of certain very slow growing microbial groups, resulting in specific gene signatures in the seafloor sediments. In our studies DNA from sediments has been extracted and sequenced by high throughput sequencing (454 Roche) and we have developed a workflow for taxonomic and functional analysis. Methane influenced sediments are typically characterised by the presence of anaerobic methanotrophic archaea with the feature of anaerobic oxidation of methane (AOM). At sites with great depth to the sulfate methane transition zone vertical fluxes enriched in carbon dioxide may enter the seafloor sediments resulting in high abundance of autotrophic prokaryotes using carbon dioxide as the as the carbon source. Annotation of the sequences to the enzymes of biochemical pathways gives information of the potential functions in the sediments. We have also used key genes involved in AOM in a client surveys north west of the Snøhvit field in the Barents Sea. Although metagenomics is a novel technology our experience so far indicates that it is a promising tool for prospecting of petroleum resources. Key words: Prospecting, Metagenomics

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013