Microbiological processes in a high-temperature oil field

Thermophilic sulfate-reducing bacteria (SRB) oxidizing lactate, butyrate, a nd C-12-C-16 n-alkanes of oil at a temperature of 90 degreesC were isolated from samples of water and oil originating from oil reservoirs of the White Tiger high-temperature oa field (Vietnam). At the same time, no thermophil es were detected in the injected seawater, which contained mesophilic micro organisms and was the site of low-temperature processes of sulfate reductio n and methanogenesis. Thermophilic SRB were also found in samples of liquid taken from various engineering reservoirs used for oil storage, treatment, and transportation. These samples also contained mesophilic SRB, methanoge ns, aerobic oil-oxidizing bacteria, and heterotrophs. Rates of bacterial pr oduction of hydrogen sulfide varied from 0.11 to 2069.63 at 30 degreesC and from 1.18 to 173.86 at 70 degreesC mug S/(1 day); and those of methane pro duction, varied from 58.4 to 100 629.8 nl CH4/(1 day) (at 30 degreesC). The sulfur isotopic compositions of sulfates contained in reservoir waters and of hydrogen sulfide of the accompanying gas indicate that bacterial sulfat e reduction might be effective in the depth of the oil field.