Understanding the Souring at Bakken Oil Reservoirs

Holubnyak, Yevhen; Bremer, J. Michael; Hamling, John A.; Huffman, Benjamin L.; Mibeck, Blaise A.F.; Klapperich, Ryan J.; Smith, Steven A.; Sorensen, James A.; Harju, John A.

doi:10.2118/141434-ms

Cited by 12 publications

(19 citation statements)

References 6 publications

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“…Assuming souring to be a problem in shale oil fields (Yevhen et al, 2011) and that nitrate injection is promising technology to remedy this problem, decreases in salinity should be avoided. The salinity of produced waters obtained in the present study varied from 0.6 to 3.7 Meq of NaCl.…”

Section: Discussionmentioning

confidence: 99%

“…In the Bakken formation 0.5 to 3 million gallons (1.9 to 11.4 million liters) of water are required per well (Wang et al, 2016). The oil from the Bakken formation is light (31° to 45° API) (Yevhen et al, 2011), but increasing concentrations of H 2 S have been observed throughout the production process (Yevhen et al, 2011). Souring of Bakken wells can be attributed to geomechanical, thermochemical and biogenic factors (Yevhen et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The oil from the Bakken formation is light (31° to 45° API) (Yevhen et al, 2011), but increasing concentrations of H 2 S have been observed throughout the production process (Yevhen et al, 2011). Souring of Bakken wells can be attributed to geomechanical, thermochemical and biogenic factors (Yevhen et al, 2011). Biogenic souring in conventional oil fields is due to the reduction of sulfate, thiosulfate or sulfur to sulfide by microorganisms (Youssef et al, 2009; Gieg et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

An¹,

Shen²,

Voordouw³

2017

Front. Microbiol.

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Microbial communities in shale oil fields are still poorly known. We obtained samples of injection, produced and facility waters from a Bakken shale oil field in Saskatchewan, Canada with a resident temperature of 60°C. The injection water had a lower salinity (0.7 Meq of NaCl) than produced or facility waters (0.6–3.6 Meq of NaCl). Salinities of the latter decreased with time, likely due to injection of low salinity water, which had 15–30 mM sulfate. Batch cultures of field samples showed sulfate-reducing and nitrate-reducing bacteria activities at different salinities (0, 0.5, 0.75, 1.0, 1.5, and 2.5 M NaCl). Notably, at high salinity nitrite accumulated, which was not observed at low salinity, indicating potential for nitrate-mediated souring control at high salinity. Continuous culture chemostats were established in media with volatile fatty acids (a mixture of acetate, propionate and butyrate) or lactate as electron donor and nitrate or sulfate as electron acceptor at 0.5 to 2.5 M NaCl. Microbial community analyses of these cultures indicated high proportions of Halanaerobium, Desulfovermiculus, Halomonas, and Marinobacter in cultures at 2.5 M NaCl, whereas Desulfovibrio, Geoalkalibacter, and Dethiosulfatibacter were dominant at 0.5 M NaCl. Use of bioreactors to study the effect of nitrate injection on sulfate reduction showed that accumulation of nitrite inhibited SRB activity at 2.5 M but not at 0.5 M NaCl. High proportions of Halanaerobium and Desulfovermiculus were found at 2.5 M NaCl in the absence of nitrate, whereas high proportions of Halomonas and no SRB were found in the presence of nitrate. A diverse microbial community dominated by the SRB Desulfovibrio was observed at 0.5 M NaCl both in the presence and absence of nitrate. Our results suggest that nitrate injection can prevent souring provided that the salinity is maintained at a high level. Thus, reinjection of high salinity produced water amended with nitrate maybe be a cost effective method for souring control.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

An¹,

Shen²,

Voordouw³

2017

Front. Microbiol.

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“…The injection of sulfate-containing seawater for maintaining the pressure of oil reservoirs can promote the growth of sulfate reducing bacteria (SRB) and archaea near the injection wells, leading to the reduction of sulfate to sulfide (Holubnyak et al 2011;Khatib and Salanitro 1997;Stemler 2012;Voordouw et al 2007;Kaster et al 2007;Machel 2001;Hubert 2010). Subsequent biologically and chemically mediated reactions result in the formation of elemental sulfur as well as other reduced sulfur compounds.…”

Section: Introductionmentioning

confidence: 99%

Reservoir souring: sulfur chemistry in offshore oil and gas reservoir fluids

Basafa

Hawboldt

2018

J Petrol Explor Prod Technol

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The injection of sulfate-containing seawater into an oil reservoir, for maintaining the reservoir pressure, can promote the growth of sulfate reducing bacteria and archaea near the injection wells, leading to the formation of sulfides such as hydrogen sulfide. However, intermediate sulfur species with different valence states, such as polythionates and polysulfides have been detected in several produced water samples, likely a result of phase partitioning, and chemical and microbial reactions. These sulfur species could affect the microbial communities (e.g., microbially influenced corrosion) and will impact the efficiency of souring mitigation methods. In addition, the presence of these sulfur species can result in operational, environmental, and treatment problems. Therefore, development and implementation of souring control strategies during production cycle of oil and gas reservoirs require identifying the origins, reactivity, and the partitioning behaviour of these compounds. This paper presents an overview of the known mechanisms responsible for reservoir souring and then focuses on the chemical reactions and sulfur species associated with production and consumption of hydrogen sulfide. In this work we highlight complexity of the sulfur chemistry and that the assumption that all the sulfate is reduced to hydrogen sulfide can lead to inappropriate souring management methods. The paper also reviews the detection and analysis methods used for sulfur compounds. The review demonstrates that there is a gap in the current souring models and methods due to the exclusion of key sulfur compounds and challenges in identifying and quantifying these compounds with respect to speed of analysis and sample stability.

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“…Production complications associated with biological contamination by deleterious bacteria in hydraulically fractured wells are well-documented and studied phenomenon (Johnson et al 2008;Agrawal et al 2011;Holubnyak et al 2011;Struchtemeyer and Elshahed 2012). This contamination can originate from several different sources.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a More Environmentally Sensitive Approach to Microbiological Control Programs for Hydraulic Fracturing Operations in the Marcellus Shale Using a Nitrate-Reducing Bacteria and Nitrate-Based Treatment System

et al. 2014

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Control of micro-organisms during the completion of hydraulically fractured wells is a significant component in the successful development of a production system. Detrimental bacteria, such as sulfatereducing bacteria (SRB), introduced into the reservoir during the completion process, can facilitate biogenic sulfide production, resulting in souring of the production fluids and gas, iron sulfide formation, and SRB associated microbiologically influenced corrosion (MIC). Biocides are routinely dosed at low levels into the fracturing fluids to control microbe populations and thus the subsequent adverse effects associated with bacterial activity. Biocides, by their very nature and intended purpose, are not well tolerated by certain aquatic organisms. In an effort to improve the ecological profile of the microbiological control program in fracturing operations, a treatment system using nitrate and nonhazardous live nitrate-reducing bacteria (NRB) for the control of SRB was developed.Nitrate-based mitigation of SRB has been used as an alternative to biocide injection in the oil and gas industry for decades. Successful SRB control using nitrate-based treatment applications has been observed in several waterflooding programs throughout the world. Nitrates stimulate the metabolic activity of NRB. NRB can mitigate SRB activity by means of three primary mechanisms: competition for available carbon sources, direct metabolic inhibition through the generation of nitrite, and certain species of NRB, which directly oxidize biogenic sulfide. This case study is an evaluation of the application of live NRB, selected for their tolerance of the temperature and salinity of the Marcellus shale, and sodium nitrate nutrient solution, as an alternative treatment to the application of biocides for hydraulically fractured wells. Both live NRB and nitrate solution were added into the fracturing fluids during the fracturing operation.Multiple wells were treated in the Marcellus shale using the tested NRB and nitrate treatment system, and these wells were monitored for periods ranging from three to 18 months depending on the date of completion. Treatment efficacy was evaluated by comparing data from the NRB and nitrate-treated wells to data collected from wells completed in the same manner and, in some cases, on the same well pad with a biocide that historically exhibited good microbial control. The results from the wells treated with NRB and nitrate demonstrated that the treatment was similarly effective compared to successful biocide applications for the control of SRB activity.

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Understanding the Souring at Bakken Oil Reservoirs

Cited by 12 publications

References 6 publications

Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

Reservoir souring: sulfur chemistry in offshore oil and gas reservoir fluids

Evaluation of a More Environmentally Sensitive Approach to Microbiological Control Programs for Hydraulic Fracturing Operations in the Marcellus Shale Using a Nitrate-Reducing Bacteria and Nitrate-Based Treatment System

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