Field research of denitrification inhibiting sulfate-reducing in crude oil gathering and transferring system
反硝化抑制石油集输系统中硫酸盐还原菌的现场实验

Aiming at the problem of high concentration of hydrogen sulfide in crude oil gathering and transferring systems of Aijiawan section in Changqing Oil field, the inhibiting function of denitrification in reducing the activities of sulfate bacteria in the process was used. The result shows that when we used the biological inhibition technique in front of the crude oil gathering and transferring systems, the concentration of H2S in sedimentation tank and sewage tank sharply decreased from 268 mg/m3 to less than 10 mg/m3 which meet the demand of Occupational Exposure Limit for Hazardous Agents in the Workplace (GBZ2-2002). The number of denitrifying bacteria increased from initial 3 000 cfu/100 mL to 600 000 cfu/100 mL as the time went on. The ORP (oxidation-reduction potential) was made to increase from -350 to -300 mV when -100 to -50 mV were just needed for denitrifying bacteria. Adding sodium nitrite to the oil well is helpful to improve ORP and is able to provide sufficient nitrogen. In our experiments, we succeeded in achieving the best inhibitory effect on the decrease of hydrogen sulfide. We also studied the change taking place in the microbial communities by using 16S rDNA gene based method. The result proves that the number of microbial communities and DNB increased effectively, it also indicates that three kind of DNB named Bacillus Halodurans, Pseudomonas alcaligenes and Neisseria played the most important role to restrain the activity of SRB in the system. The study developed the biological inhibition technique of H2S produced by SRB, and confirmed the feasibility of treatment technology and process application.