scholarly journals Long-term biocide efficacy and its effect on a souring microbial community

2021 ◽  
Author(s):  
Xiang Shi ◽  
Daiane A. F. Oliveira ◽  
Lea Holsten ◽  
Katrin Steinhauer ◽  
Julia R. de Rezende
Keyword(s):  
Microbial Community ◽  
Microbial Ecology ◽  
Oil Quality ◽  
Oil And Gas Industry ◽  
Control Programme ◽  
Sulfate Reducing ◽  
Microbial Community Analyses ◽  
One Year ◽  
Biocide Treatment

Reservoir souring, which is the production of H 2 S mainly by sulfate-reducing microorganisms (SRM) in oil reservoirs, has been a long-standing issue for the oil industry. While biocides have been frequently applied to control biogenic souring, the effects of biocide treatment are usually temporary, and biocides eventually fail. The reasons behind biocide failure and the long-term response of the microbial community remain poorly understood. In this study, one time biocide treatments with glutaraldehyde (GA) and an aldehyde-releasing biocide (ARB) at low (100 ppm) and high (750 ppm) dosages were individually applied to a complex sulfate-reducing microbial community, followed by one-year monitoring of the chemical responses and the microbial community succession. The chemical results showed that souring control failed after 7 days at 100 ppm dosage regardless the biocide type, and that lasting souring control for the entire one-year timespan was only achieved with ARB at 750 ppm. Microbial community analyses suggested that the high dosage biocide treatments resulted in one order of magnitude lower average total microbial abundance and average SRM abundance compared to the low dosage treatments. The recurrence of souring was associated with reduction of alpha diversity and with long-term microbial community structure change, thus monitoring changes in microbial community metrics may serve as early warnings of the failure of a biocide-based souring control programme in the field. Furthermore, spore-forming sulfate reducers ( Desulfotomaculum and Desulfurispora ) were enriched and became dominant in both GA-treated groups, which could cause challenges to the design of long-lasting remedial souring control strategies. IMPORTANCE Reservoir souring is a detrimental problem for the oil and gas industry as H 2 S corrodes the steel infrastructure, downgrades the oil quality and poses substantial risks to the field personnel and the environment. Biocides have been widely applied to remedy souring, yet the long-term performance of biocide treatments is hard to predict or optimise due to limited understanding of the microbial ecology affected by biocide treatment. This study investigates the long-term biocide performance and associated changes in the abundance, diversity and structure of the souring microbial community, thus advancing the knowledge towards a deeper understanding of the microbial ecology of biocide-treated systems, and contributing to the improvement of current biocide-based souring control practices. The study showcases the potential application of incorporating microbial community analyses to forecast souring and highlights the long-term consequences of the biocide treatment on the microbial communities, with relevance to both operators and regulators.

Microbial Ecology Metrics to Assess the Effect of Biocide on Souring Control and Improve Souring Modelling

2021 ◽  
Author(s):  
Xiang Shi ◽  
Julia R. de Rezende ◽  
Kenneth Sorbie
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Ecology ◽  
Oil And Gas ◽  
Produced Water ◽  
Control Strategies ◽  
Alpha Diversity ◽  
Oil And Gas Industry ◽  
Near Term ◽  
Biocide Treatment

Abstract Reservoir souring is a long-standing issue for the oil and gas industry caused by sulfate-reducing microorganisms (SRM) producing H2S from sulfate ions. In this work, we investigated the connections between the development of souring and the change in three key microbial ecology metrics: the abundance, alpha diversity and community structure of a souring microbiota under the biocide treatment of 100 ppm glutaraldehyde (henceforth referred to as GA). These are studied in sand-packed flow-through bioreactors during and after the biocide treatment using cutting-edge DNA assays. Our study suggests that the rebound of microbial sulfide production after the 100 ppm GA treatment is closely associated with the recovery in microbial abundance and microbial alpha diversity. The study also shows that 100 ppm GA treatment may lead to a measurable shift in the SRM community structure. By comparing the effluent microbial community with the sand microbial community, the study suggests that the change in alpha diversity of the produced water microbial community might be an early warning for the sulfide breakthrough due to souring recurrence in practice. This work explores the relationship between souring and the underlining microbial community behaviours in response to the 100 ppm GA treatment and, to characterise these changes, we propose measurable metrics. A conceptual model is also proposed describing the near-term biological process behind the biocide treatment-recovery cycle in a souring scenario. Finally, this work highlights the potential applications and caveats of harnessing the increasingly available field microbial community data for the improvement of souring modelling and field souring control strategies.

scholarly journals Diversity decoupled from sulfur isotope fractionation in a sulfate reducing microbial community

2019 ◽  
Author(s):  
Jesse Colangelo ◽  
Claus Pelikan ◽  
Craig W. Herbold ◽  
Ianina Altshuler ◽  
Alexander Loy ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Ecology ◽  
Sulfate Reduction ◽  
Isotope Fractionation ◽  
Sulfur Isotopes ◽  
List Type ◽  
Natural Habitats ◽  
Sulfate Reducing ◽  
Sulfate Reduction Rates

AbstractThe extent of fractionation of sulfur isotopes by sulfate reducing microbes is dictated by genomic and environmental factors. A greater understanding of species-specific fractionations may better inform interpretation of sulfur isotopes preserved in the rock record. To examine whether gene diversity influences net isotopic fractionation in situ, we assessed environmental chemistry, sulfate reduction rates, diversity of putative sulfur metabolizing organisms by 16S rRNA and dissimilatory sulfite reductase (dsrB) gene amplicon sequencing, and net fractionation of sulfur isotopes along a sediment transect of a hypersaline Arctic spring. In situ sulfate reduction rates yielded minimum cell-specific sulfate reduction rates <0.3 x 10−15 moles cell−1 day−1. Neither 16S rRNA nor dsrB diversity indices correlated with relatively constant (38 to 45‰) net isotope fractionation (ε34Ssulfide−sulfate). Measured ε34S values could be reproduced in a mechanistic fractionation model if 1-2% of the microbial community (10-60% of Deltaproteobacteria) were engaged in sulfate respiration, indicating heterogeneous respiratory activity within sulfate-metabolizing populations. This model indicated enzymatic kinetic diversity of Apr was more likely to correlate with sulfur fractionation than DsrB. We propose that, above a threshold alpha diversity value, the influence of the specific composition of the microbial community responsible for generating an isotope signal is overprinted by the control exerted by environmental variables on microbial physiology.Subject categoriesIntegrated genomics and post-genomics approaches in microbial ecologyMicrobial ecology and functional diversity of natural habitats

PAH natural attenuation in Mediterranean forest soils

2020 ◽  
Author(s):  
Enrica Picariello ◽  
Erland Bååth ◽  
Daniela Baldantoni ◽  
Flavia De Nicola
Keyword(s):  
Microbial Community ◽  
Forest Soils ◽  
Natural Attenuation ◽  
Contaminated Soils ◽  
Holm Oak ◽  
Soil Microbial ◽  
Pah Degradation ◽  
One Year ◽  
Microbial Groups

&lt;p&gt;Polycyclic aromatic hydrocarbons (PAHs) are worldwide contaminants and, due to their long-range transport, they can accumulate far from the emission sources, in carbon-rich forest soils; thus new exploration in the indigenous microbial response to PAH exposure is important to deeper understanding of PAH natural degradation process. Since most of the studies are limited to aged PAH contaminated soils, we aimed to fill the gap in our knowledge on recent contamination.&amp;#160;&lt;br&gt;In order to investigate indigenous microbial community involvement in soil PAH degradation, a mesocosm trial was established. Soils from two forest systems (holm oak and black pine) were spiked with 3 PAHs (phenanthrene, pyrene and benzo[a]pyrene) and incubated under controlled conditions (T: 22 &amp;#176;C, R.H.: 88%). Along 360 days, structural and functional changes in soil microbial community were monitored analyzing bacterial and fungal biomass (by phospholipid fatty acid and ergosterol content) and enzyme activities (hydrolase, laccase and peroxidase).&lt;br&gt;Both soil types indicated a capability of indigenous native microbial community to degrade almost completely PAHs yet after one year, with phenanthrene and pyrene faster degrading than benzo[a]pyrene, according to their molecular weight. In pine soil, the PAH degradation proceeds with a minor extent likely in relation to the sequestration of PAHs in soil richer in organic matter. In both forest soils fungi are mainly involved in the degradation of PAHs, as highlighted by the increase of both content of the fungal marker and enzyme activity mainly carried out by fungi, e.g. laccase in holm oak soil.&amp;#160;&lt;br&gt;Regarding the community structure, PAH contamination influences the relative abundance of several soil microbial groups yet after 4 days from contamination, when the microbial community composition shifts towards Gram+ bacteria in holm oak soil, whereas in pine soil pyrene and phenanthrene stimulate fungi and actinomycetes. In the long-term, after one year from contamination, a variation in microbial community was more evident in the holm oak soil, with an increase of fungi in the treatment with benzo[a]pyrene, and an increase of Gram+ in the treatment with phenanthrene. All the enzymes activities, after some fluctuations in the early stages of incubation, decreased after one year. During the quick and strong PAH degradation, hydrolytic activity showed high and constant values, exhibiting a stability in the long-term after the contamination.&amp;#160;&lt;br&gt;The obtained findings show the role of several microbial groups in PAH natural attenuation in different forest soils. Different PAH degradation rates between systems can be attributable to soil microbiome dominated by different populations in the two investigated forest soils. The use of indigenous microorganisms in bioremediation processes can reduce the risks associated with PAH contaminated soils, and a better understanding of the effects of PAH contaminants on soil microbial community is very critical for understanding microbial activity during bioremediation. The findings highlight the importance of fungi in the potential recovery of a soil polluted by organic contaminants.&lt;/p&gt;

scholarly journals Evaluation of the « Time/Risk » Probability of being Infected and its Evolution Before/After a Long Term Village Scale Malaria Vector Control Programme in Angola

2021 ◽  
pp. 36-48
Author(s):  
P. Carnevale ◽  
N. Carnevale ◽  
G. Carnevale
Keyword(s):  
Vector Control ◽  
Classical Method ◽  
Control Programme ◽  
Control Measures ◽  
Malaria Vector Control ◽  
Reproduction Rate ◽  
Insecticide Treated Nets ◽  
Vector Control Programme ◽  
One Year

Three main entomological indicators are classically used in the epidemiology of malaria: the inoculation rate (“h”) of Ross, the vectorial capacity (“C”) of Garrett-Jones and the reproduction rate (“z”) of Macdonald. In spite of their undoubtfully usefulness it appeared that their formulae did not integrate the key parameter of “t” i.e. the time of exposure and therefore the probabilities of being infected according to the entomological condition (density, infectivity, longevity of the vectors) but also the time/risk and the reduction of this risk when some village-scale vector control measures are implemented. To deal with this approach we used the Briley’s formula, elaborated some years ago, to analyze the time/risk of being infected in the framework of a long term village scale vector control programme implemented around Balombo (Benguela Province, Angola) with classical method (inside residual spraying) and newly developed tool s (insecticide treated plastic sheeting) used alone or in association with the classical long lasting insecticide treated nets. Before vector control the risk was almost 20% in one week, 60% in one month and 100% in 3 months and this explain why plasmodic index are so high in this area without any organized vector control programme. The 3 methods actually reduced the risks which become of the order of 2% in one week, 10% in one month, 26% in one trimester but 70% in one year; the three methods had the same efficacy in reducing these risks. The fact that the risk reach 70% in one year even with right vector control shows the needs of renewing regularly the operations, the needs of other than entomological methods of prevention but also that immunity could be maintained and feared “rebound” was not observed even during the long term of the programme.

Trends and Prospects of Development of the Oil and Gas Sector in the Context of Digitalization

2020 ◽  
Vol 26 (1) ◽  
pp. 35-45 ◽  
Author(s):  
A. G. Kazanin
Keyword(s):  
Oil And Gas ◽  
Digital Technologies ◽  
Oil And Gas Industry ◽  
Global Market ◽  
The Arctic ◽  
Business And Society ◽  
Gas Industry ◽  
Exploration And Production ◽  
Oil And Gas Sector

The modern oil and gas industry is heavily dependent on the processes and trends driven by the accelerating digitalization of the economy. Thus, the digitalization of the oil and gas sector has become Russia’s top priority, which involves a technological and structural transformation of all production processes and stages.Aim. The presented study aims to identify the major trends and prospects of development of the Russian oil and gas sector in the context of its digitalization and formation of the digital economy.Tasks. The authors analyze the major trends in the development of the oil and gas industry at a global scale and in Russia with allowance for the prospects of accelerated exploration of the Arctic; determine the best practices of implementation of digital technologies by oil and gas companies as well as the prospects and obstacles for the subsequent transfer of digital technologies to the Russian oil and gas industry.Methods. This study uses general scientific methods, such as analysis, synthesis, and scientific generalization.Results. Arctic hydrocarbons will become increasingly important to Russia in the long term, and their exploration and production will require the implementation of innovative technologies. Priority directions for the development of many oil and gas producers will include active application of digital technologies as a whole (different types of robots that could replace people in performing complex procedures), processing and analysis of big data using artificial intelligence to optimize processes, particularly in the field of exploration and production, processing and transportation. Digitalization of the oil and gas sector is a powerful factor in the improvement of the efficiency of the Russian economy. However, Russian companies are notably lagging behind in this field of innovative development and there are problems and high risks that need to be overcome to realize its potential for business and society.Conclusions. Given the strategic importance of the oil and gas industry for Russia, its sustainable development and national security, it is recommendable to focus on the development and implementation of digital technologies. This is crucial for the digitalization of long-term projection and strategic planning, assessment of the role and place of Russia and its largest energy companies in the global market with allowance for a maximum number of different internal and external factors.

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