Bacteria

Bacteria are ubiquitous in the environment but will concentrate where a food source is available. Hydrocarbon microseepage from oil and gas reservoirs provide this food source. Microbial activity provides a catalyst for the various "redox" chemical reactions that occur within a live seepage anomaly. Oxidation of the hydrocarbons provides an electron rich environment for these reactions.

Bacteria are available that use specific substrates such as ethane, propane, or butane. GRDC uses a method that is non-specific and primarily looks at aerobic bacteria that live in very near surface soils which can oxidize any number of organic substrates.  The culturing is fairly rapid (36 to 48 hours) and results in a color change that is equivalent to the microbial concentration.

Image analysis is used to facilitate the counting process. The scale is set from 0-256 channels where 256 indicates a lack of bacteria and 0 indicates complete color saturation. The histogram of the channels is evaluated and a mean value is determined. These means are then plotted in map view for interpretation.

This provides a good economical reconnaissance tool to indicate the probable presence of hydrocarbon micro seepage.