| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1249-2 | ||||
Resumo:Produced water, which is a byproduct from oil extraction, can be reused as injection water to enhance oil production. Before being employed as an injection fluid, produced water typically undergoes a flotation procedure to separate water from residual oil. However, the injection of produced water can potentially cause effects postflooding on the oil reservoir, such as biogenic acidification and microbial-influenced corrosion, primarily driven by the increase in the sulfate-reducing bacteria (SRB) population within the reservoir. The produced water used as an injection fluid is usually unexplored regarding microbial community composition. Thus, our study assessed the microbial composition and the predicted function in produced water and examined the influence of flotation on the microbial community structure. For this purpose, samples obtained from a Brazilian oil platform collected (i) before (BF) and (ii) after flotation (AF) were analyzed. To elucidate the effect of the flotation stage on the microbial community, the obtained 16S rRNA-encoding gene sequences were analyzed using the QIIME 2 program. Additionally, functional abundances of the microbial community were predicted via metabolic pathways using PICRUSt2. Regarding microbial community composition, the results showed that the relative abundance of SRB represented 71% of the microbial community observed in BF and 53% in AF. The most abundant genera identified in the BF samples were related to Desulfothermus (36%), Desulfonauticus (28%) and Desulfomicrobium (7%). In relation to AF, the most abundant genera were related to Desulfonauticus (32%), Desulfothermus (16%) and Desulfomicrobium (5%). The PICRUSt2 results showed that the abundance of genes related to the denitrification pathway was higher in the AF (0.015) than in the BF (0.010). The same pattern was observed for the dissimilatory sulfate reduction pathway (0.008 > 0.002). For assimilatory sulfate reduction, the abundance was higher in the BF (0.017) than in the AF (0.008). Our results showed that the flotation of produced water promoted changes in microbial community structure and function. However, although our results showed that flotation resulted in a decrease in SRB abundance in the produced water, the majority of the microbial community present in AF samples was still related to sulfate-reducing bacteria (53%). The abundant presence of these microorganisms poses a potential risk to the integrity of the oil reservoir. Considering the aforementioned factors, mapping and predicting the behavior of the microbial community in water injection systems will allow the establishment of more efficient mitigation strategies for microorganisms during secondary oil recovery. Palavras-chave: flotation, microbial control, secondary oil recovery, sulfate-reducing bacteria, water injection Agência de fomento:Petrobras | |||||