| A large number of sulfate-reducing bacteria (SRB) have been detected in the system of oilfield injection-water for secondary exploitation of petroleum. With the ability of reducing sulfate to sulfide that leads to mass propagation of cells, SRB seriously caused the corrosion of ground facilities and underground pipelines and create sulfide pollution, causing considerable economic loss to oilfield. Traditional techniques inhibiting/killing SRB, such as physical and chemical methods, have presented strong negative effects in practice and could not solve the problem fundamentally. Meanwhile, such actions cost too much and bring serious environmental problems.In recent years, microbial control methods by biological competitive inhibition have been proposed to inhibit pipeline corrosion in oilfield and degradation of polymers caused by SRB. The principle employed is based on competition and antagonist between microorganisms. Specifically, by introducing a certain amount of inorganic salts to favor the growth of denitrifying bacteria (DNB), which will outcompete SRB by utilizing the organic carbons and electron donors and the living space preferentially, and thus inhibit corrosion to metal pipeline of SRB.In this study, a SRB strain SRB-1and a DNB strain DNB-1from the injection water at Daqing Oilfield were isolated and further identified as Garciella nitratireducens and Pseudomonas stutzeri, respectively, by phenotypical characteristics and16S rDNA sequence alignments.And then, the competitive inhibition experiment was carried out between SRB-1and DNB-1. The results showed that:adding DNB with a certain amount (e.g.,500mg/L) of NaNO3or NaNO2into the produced water of oilfield, were good for the inhibition effect on the growth of SRB and the activity of reducing SO42-into S2-for a certain period of time (e.g.,20d), while adding DNB only without NaNO3or NaNO2presented less effective inhibition effects than addition of DNB with NaNO3or NaNO2. |
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