Study of ecological inhibition of sulfate-reducing bacterial activity and associated population succession in oilfield flooding water

In the conventional water flooding process of Daqing Oilfield in China, the occurrence of abundant sulfate-reducing bacterial populations has substantially affected the industrial production. This study was conducted from the perspective of ecological suppression by operating anaerobic ABR reactors and dosing ecological inhibitors in a continuous-flow experiment. The practical operating efficacy was investigated and associated dynamic bacterial population succession was analyzed. Results showed that the sulfate removal rate decreased upon the addition of eco-inhibitor, leading to a low concentration of sulfide products (<0.3 mg/L). Associated redox potential substantially varied from -300 mV to approximately -50 mV, whereas the pH and alkalinity slightly changed and imposed a minor effect on the reaction system. There were significant changes in microbial diversity before and after the eco-suppression, and dominant functional bacterial populations shifted from sulfate-reducing bacteria (Thauera selenatis, Desulfovibrio sp., Clostridium diolis Hydrogenophaga taeniospiralis) to those capable of denitrification (Uncultured firmicute, Clostridium butyricum, Paenibacillus lautus, Arcobacter cibarius). These indicated that the utilization of eco-inhibitor has successfully inhibited the sulfate-reducing bacterial activities.