A new control strategy of sulfate-reducing microorganisms and corrosion rate from a high-temperature oil reservoir by nitrate/nitrite coupling with nitrate-reducing bacteria

Different water-flooded oil reservoirs shape diverse compositions of sulfate-reducing microorganisms (SRM), and the activities of key SRM may involve different metabolic, corrosion and inhibition mechanisms. However, the current bioinhibition methods for SRM in various petroleum reservoirs are complex and variable, and universal and systematic model methods are lacking for field application. In the present study, the effective inhibition of SRM from the production water of the Jiangsu Oilfield was investigated using inhibitors and nitrate-reducing bacteria (NRB). The experiments, involving different concentrations of selective inorganic inhibitors, showed that nitrate and nitrite exhibited prominent inhibitory effects on the SRM community (JS) with sulfide reduction by 49.0%-62.5%, followed by molybdate and tungstate. With the target of the key SRM (Archaeoglobus) in the production water of the Jiangsu Oilfield, nitrate/nitrite and three NRB strains were evaluated for their inhibition performance. The nitrate-containing treatments were more related to the NRB species, whereas the nitritecontaining treatments were more related to nitrite concentrations. Comparatively, the sulfide inhibition of the nitrite-containing treatments was more significant, with an obvious influence on enzyme contents (Apr and Dsr). Two preferred inhibition combinations were obtained: nitrate (10 mmol/L) and ZW3; nitrite (5 mmol/L) and ZW3. They have been applied in the SRM community (JS) for effectiveness evaluation, with excellent performance in the control of sulfide production and corrosion rate. A nitrate-mediated model method for the bioinhibition of SRM in oil reservoirs is proposed. These results provide insights and strategies for microbial inhibition of SRM and corrosion control in oilfields.