Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.
Environ Sci Technol. 2012 Jan 17;46(2):1285-92. doi: 10.1021/es203748b. Epub 2012 Jan 4.
Souring in the Medicine Hat Glauconitic C field, which has a low bottom-hole temperature (30 °C), results from the presence of 0.8 mM sulfate in the injection water. Inclusion of 2 mM nitrate to decrease souring results in zones of nitrate-reduction, sulfate-reduction, and methanogenesis along the injection water flow path. Microbial community analysis by pyrosequencing indicated dominant community members in each of these zones. Nitrate breakthrough was observed in 2-PW, a major water- and sulfide-producing well, after 4 years of injection. Sulfide concentrations at four other production wells (PWs) also reached zero, causing the average sulfide concentration in 14 PWs to decrease significantly. Interestingly, oil produced by 2-PW was depleted of toluene, the preferred electron donor for nitrate reduction. 2-PW and other PWs with zero sulfide produced 95% water and 5% oil. At 2 mM nitrate and 5 mM toluene, respectively, this represents an excess of electron acceptor over electron donor. Hence, continuous nitrate injection can change the composition of produced oil and nitrate breakthrough is expected first in PWs with a low oil to water ratio, because oil from these wells is treated on average with more nitrate than is oil from PWs with a high oil to water ratio.
在 Medicine Hat Glauconitic C 气田，由于注入水中含有 0.8 mM 的硫酸盐，导致回注井底温度（30°C）较低。添加 2 mM 的硝酸盐来抑制酸化，导致在注入水流路径上形成硝酸盐还原、硫酸盐还原和产甲烷带。焦磷酸测序的微生物群落分析表明，在这些区域中都存在优势的微生物群落成员。在注入 4 年后，主要产水和产硫化物的 2-PW 井中出现了硝酸盐突破。其他四口生产井（PW）的硫化物浓度也降至零，导致 14 口生产井的平均硫化物浓度显著下降。有趣的是，2-PW 井生产的石油中甲苯耗尽，甲苯是硝酸盐还原的首选电子供体。2-PW 和其他零硫化物生产井的产水率为 95%，产油率为 5%。在分别添加 2 mM 硝酸盐和 5 mM 甲苯的情况下，电子受体的含量超过了电子供体。因此，连续的硝酸盐注入会改变产出油的组成，预计硝酸盐突破首先会发生在油井产出比（即产油量与产水量的比值）较低的井中，因为这些井的油平均需要比油井产出比高的井更多的硝酸盐处理。
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