Voordouw, GerritOkpala, Gloria2017-10-232017-10-2320172017Okpala, G. (2017). Control of Microbial Sulfide Production in Low and High Temperature Oil Field with Nitrate and Perchlorate (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25453http://hdl.handle.net/11023/4226The activity of sulfate reducing bacteria (SRB), which produce sulfide, in low and high temperature oilfields, poses a severe challenge for oil and gas industries. Nitrate injection is used to limit the growth of SRB, through stimulation of nitrate reducing bacteria (NRB) that reduce nitrate to nitrite and subsequently to N2. Data from temperature dependent studies done in this work reveal thermophilic nitrate reducing bacteria (tNRB) isolated from low and high temperature oilfields reduce nitrate to nitrite and not further at 50°C or above. This observation is especially important for nitrate-mediated control of sulfide production in high temperature oil fields, because nitrite is a strong SRB inhibitor. To better understand how nitrate injection works in a seawater flooded high temperature reservoir, dual temperature bioreactors and multi-temperature microcosms were used in monitoring sulfate reduction by mesophilic and thermophilic NRB and SRB. The results indicated that nitrate may be ineffective when injected into a cold zone (<45°C) and that preventing emergence of such a zone by injecting hot produced water may be an effective way to control souring with nitrate. Control of souring with perchlorate under low temperature conditions in batch incubations and bioreactors containing heavy oil was also tested. Perchlorate caused a delay in the onset of sulfate reduction in batch incubations. However, its reduction with oil was not seen in batch culture incubations or bioreactors. Chlorite was more effective at inhibiting SRB activity under these conditions. The research in this thesis thus contributes to improved management of sulfide production in oil fields.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.MicrobiologyOil fieldSulfate reductionNitrate reductionPerchlorate reductionMicrobial communitydoctoral thesis10.11575/PRISM/25453