Induced Biochemical Interactions in Immature and Biodegraded Heavy Crude Oils

Studies in which selective chemical markers have been used to explore the mechanisms by which biocatalysts interact with heavy crude oils have shown that the biochemical reactions follow distinct trends. The term "biocatalyst" refers to a group of extremophilic microorganisms which, under the experimental conditions used, interact with heavy crude oils to: 1. Cause a redistribution of hydrocarbons. 2. Cause chemical changes in oil fractions containing sulfur compounds and lower the sulfur content. 3. Decrease organic nitrogen content. 4. Decrease the concentration of trace metals. Current data indicate that the overall effect is due to simul- taneous reactions yielding products with relatively higher concentration of saturates and lower concentrations of aro- matics and resins. The compositional changes depend on the microbial species and the chemistry of the crudes. Economic analysis of a potential technology based on the available data indicate that such a technology, used in a pre-refinery mode, may be cost efficient and promising. In the present paper, the background of oil biocatalysis and some recent results will be discussed. Background