Dynamics of Microbial Community and Removal of Hydrogen Sulfide (H₂S) Using a Bio-Inhibitor and Its Application under the Oil Reservoir Condition

Abstract

Hydrogen sulfide (H 2 S) is a toxic gas widespread in injected water of secondary oil recovery, having disadvantages of serious corrosion equipment, health risks, and higher operational costs. This study focused on the field application with nitrate and nitrite injection, which has been less examined in previous studies. A bioinhibitor (400 mg/L nitrate + 300 mg/L nitrite) was reinserted into the water of the M71 oilfield (Jianghan Basin, China) with serious souring. The concentration of H 2 S decreased by 83% from 30 mg/L to less than 5 mg/L; the nitrate-reducing bacteria (NRB) counts increased from 10 to 100 cfu/mL, and the sulfate-reducing bacteria (SRB) counts remained at low numbers (0 cfu/mL). The dominant genera in the injected water in the absence of the bio-inhibitor were Desulfuromonas, Halanaerobium, and Desulfovibrio. NRB-related Halomonas and Marinobacter and sulfide-oxidizing bacteria of Halothiobacillus and Pseudomonas were activated through competing with SRB electron donors, and sulfide-oxidizing bacteria oxidized H 2 S to S 0 or SO 4 2− to suppress SRB when the bio-inhibitor was continuously added. The nitrite inhibited SRB metabolism through suppressing sulfite reductase activity. These findings indicated that the addition of the bio-inhibitor could remove H 2 S efficiency in injected water, thereby causing water reinjection in the oil reservoir. As a result, cost-effective treatments for souring control are achieved.

Microbial Communities in Model Seawater-Compensated Fuel Ballast Tanks: Biodegradation and Biocorrosion Stimulated by Marine Sediments

“…croflora. A low rate of oxygen diffusion across the polycarbonate housing the reactors was hypothesized as a reason for the limited sulfate reduction activity and the possible promotion of sulfide oxidation [39][40][41][42] consistent with the detection of a high relative abundance of sulfide-oxidizing bacteria in two of the reactors [18]. The relatively low levels of sulfate reduction and dissolved iron suggested that the rate of corrosion was relatively slow.…”

Microbial Communities Associated with Alternative Fuels in Model Seawater-Compensated Fuel Ballast Tanks

“…Sulfide-oxidizing bacteria could oxidize sulfide formed by the sulfate-reducing bacteria, recycling the sulfur to more oxidized sulfur species [44]. Indeed, Deng et al [46], after injecting nitrate and nitrite into an oil field with high H 2 S concentrations, noted that as H 2 S concentration and SRB levels dropped, the relative abundance of both nitrate/nitrite reducers and sulfide-oxidizing bacteria rose. In our study, reactors 2 and 6 among the fuel-containing reactors were noteworthy for a high relative abundance of sulfide-oxidizing Arcobacter (Epsilonproteobacteria) and other taxa belonging to Alpha-and Gammaproteobacteria and Flavobacteriia with the potential for sulfide oxidation (Figures 5 and 6).…”