f Investigation of Sulphate Reducing Bacteria in Petroleum Reservoirs of Dodan, Garzan ve Silivanka Fields (Se-Turkey)

For metabolic activities, sulphate reducing bacteria (SRB) reduce sulfate to hydrogen sulphide (H2S) which is highly toxic and corrosive. The generated H2S causes corrosion of various metals including stainless steels, copper alloys etc. in oil wells and in the oil-processing system. In addition, the production of toxic H2S may present a health hazard to the platform personnel and diminish oil quality by the souring of oil and gas. The aim of this study was to determine the abundance and distribution of SRB in the reservoirs of Dodan, Garzan and Silivanka Oil Fields. Petroleum samples were collected from 8 different reservoirs in the Dodan, Garzan and Silivanka Oil Fields. Two samples from each reservoir were taken and one of them was used for obtaining water phase of oil. Postgate medium B, with and without salt (NaCl), was used for isolation of SRB from oil and oil-water phase of the samples. SRB counts in the samples were determined by the MPN (Most Probable Number-MPN) technique. The culturing was carried out in duplicate and while one of the series was incubated at 30°C, other series were kept at 55°C for 3 months. At the end of the incubation period, the growth of SRB was not observed in the oil and oilwater phase samples taken from Dodan 17M, Dodan 6S and Silivanka 28 oil fields. However, SRB were especially isolated from oil-water phase samples obtained from Garzan 17, Garzan 89 and Silivanka 31 oil fields. It was determined that oil-water phase samples of the Garzan 17 oil field, which were incubated at 30°C, contained a high number of SRB (107 cell/ml). Our results showed that the number of SRB in the oil-water phase was generally higher than in the oil. In addition, it was determined that SRB isolates obtained from these oil fields need to salt for their growth and also they grow better in mesophilic conditions (20°C-45°C).