The paper cover the lab and pilot tests results on reduction of sulfate-reducing bacteria activity in produced water of oil gathering, transportation and treatment systems at Vietsovpetro offshore facilities. Based on field tests results, developed the requirements to biocides, recommended for application on the offshore oil producing facilities. It is recommended to select biocides and conditions for its application at the certain oil field, based on lab and pilot tests results following further gathering of associated water samples and its analysis on sulphate-reducing bacteria and hydrogen sulphide content. While performing the biocides pilot testing, the emphasis should be made towards not only the effective suppression of sulphate-reducing bacteria activity, but also the physical-chemical interaction with other field chemicals in order to avoid negative effect on technological processes of oil treatment. Confirmed, that the planktonic sulphate-reducing bacteria almost immediately suppressed by minimal concentrations of biocides (120–150 ppm), but rapidly recover due to the product infected by sulphate-reducing bacteria, which received from other offshore fixed platforms. To suppress sedentary (filmy) types of sulphate-reducing bacteria the higher biocide concentrations (above 500 ppm) is required. Suppression of sulphate-reducing bacteria at process platforms of oil treatment led to the reduction of dissolved hydrogen sulphide by 3–4 times in produced water. It is recommended to apply quick tests for identifying the infection grade by the sulphate-reducing bacteria and the efficiency of biocides in field conditions only for preliminary assessment, while the final evaluation on sulphate-reducing bacteria content should be performed by the standard API RP 38 method with the identification of the sulphate-reducing bacteria forms (sedentary/planktonic).
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