MICROBIOLOGICAL OIL PROSPECTING IN AUSTRALIA

Abstract

Russian, American and Czechoslovakian scientists have shown that soils associated with oilfields contain bacteria which actively utilise hydrocarbons. The technique of microbiological oil exploration seeks to measure those soil bacteria which grow on gaseous hydrocarbons migrating from oil and gas pools, and to distinguish them from other bacteria also capable of utilising hydrocarbons, hut whose presence in the soil is due to soil organic matter.

Using radioactive tracers and gas chromatography, we have developed methods for measuring these bacteria. The measurements are most accurate when the bacteria are growing in the logarithmic phase, the time required to reach this phase increasing as the number of bacteria decrease.

Bacteria grow at ethane concentrations as low as five parts per million in air, higher concentrations of ethane supporting greater bacterial activities in the soil. The growth of indigenous or inoculated bacteria on hydrocarbon gas is markedly affected by the soil environment.

Small-scale surveys have been made at Moonie, Cabawin, Grange, Mt. Salt, Glen Davis, Geltwood Beach and Lakes Entrance. High rates of hydrocarbon utilisation have been found in a few samples from two of these surveys, but no large area of high activity has been discovered.