Mapping of Microbial Habitats in Organic-Rich Shale

Buchwalter, E.; Swift, A.; Sheets, J.; Cole, David R.; Prisk, Timothy; Anovitz, Lawrence M.; Ilavský, Ján; Rivers, Mark L.; Welch, Susan A.

doi:10.15530/urtec-2015-2174226

Cited by 2 publications

(4 citation statements)

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“…Hydraulic fracturing involves injecting chemically amended water at high pressure from the ground surface into a horizontal well in order to fracture the shale formation and provide conduits for hydrocarbon flow. This process introduces non-native microorganisms from the ground surface and promotes fluid transport and mixing within shale fractures during fracturing and subsequent hydrocarbon recovery. − Many unconventional reservoirs are characterized by high total dissolved solid levels, and a major constituent is sulfate. , Organic acids are the common microbial breakdown products of hydrocarbons and other organic matter from shale, − and the presence of sulfate and organic acids, coupled with fluid transport and mixing in fractures, promotes the growth of sulfate-reducing bacteria (SRB) . These microorganisms can clog fractures and lower hydrocarbon production , and produce highly corrosive and toxic sulfides in the produced oil and water that can compromise well casing, pipes, valves, and tanks and shut down production. , The latter process is often referred to as biological souring; this and the closely related process known as microbially induced corrosion cost the global oil and gas industry tens of billions of USD each year. , They can also lead to the release of produced oil and water to the environment and represent both human health and environmental concerns. , These concerns motivate the focus of this work, which is to determine how biogeochemical conditions affect SRB growth, distribution, and activity of sulfate reduction to sulfide in shale fractures.…”

Section: Introductionmentioning

confidence: 99%

Rates of Sulfate Reduction by Microbial Biofilms That Form on Shale Fracture Walls within a Microfluidic Testbed

et al. 2022

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Microbial sulfate reduction (biosouring) is ubiquitous in natural and engineered environments. It can be especially problematic during oil recovery from unconventional reservoirs, where the growth of sulfate-reducing bacteria (SRB) biofilms can clog fracture pathways, decrease hydrocarbon production, and produce hydrogen sulfide in the produced oil and water that corrodes pipelines and threatens both human health and the environment. Relevant experimental data on shale fractures, assessing the conditions that affect SRB growth, distribution, and activity for sulfate reduction, are sparse, and this has limited our ability to evaluate predictive models for assessing the impacts. To address this limitation, a 250 μm wide, 170 μm deep, and 2 cm long microchannel was constructed within an actual sample of subsurface core from the Devonian age New Albany Shale of the Illinois Basin to simulate a hydraulically induced fracture (fracked shale). This real rock flow-through microfluidic system, called the GeoBioCell (GBC), was designed with two inlets and one outlet. At flow rates of 3.4−80 μL/h, an SRB enrichment culture with hydrocarbon degradation products (i.e., fatty acids) was fed into one inlet, while dissolved sulfate (30 mM) was introduced into the other inlet. These were not allowed to mix until they entered the microchannel, where rapid biomass growth and sulfate reduction took place. SRB biomass was quantified as a function of both influent sulfate flux using brightfield microscopy and SRB metabolic sulfide production using an effluent zinc trap. Results indicate that biomass grows on shale fracture walls and in the channel and increases with the influent organic acid and sulfate flux, and that the downflow SRB biofilm growth on microchannel walls is limited by the upstream metabolic consumption of electron donors. An advection-diffusion-reaction model was developed to interpret these results, and a specific sulfate reduction rate of 1.0 ± 0.4 × 10 −3 mmol SO 4 2− /(mmol biomass•s) or 9 ± 4 × 10 −6 mmol SO 4 2− /(mg biomass•s) was obtained. This rate, among the highest reported to date, suggests that nearly optimal conditions for SRB sulfate reduction were attained within the microchannel that were independent of mass transfer limitations. Future tests using similar real rock microfluidic experimentation will be useful for assessing worst case scenarios for subsurface reservoir biosouring models and establishing new mitigation strategies to prevent adverse human health and environmental impacts.

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Section: Introductionmentioning

confidence: 99%

Rates of Sulfate Reduction by Microbial Biofilms That Form on Shale Fracture Walls within a Microfluidic Testbed

et al. 2022

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“…The permeability of the Mahantango Formation estimated to be 6 millidarcy (mD), higher than the 2.5 mD in Marcellus Shale Top and the Upper Marcellus Shale (Paronish, 2017), could also have influenced microbial presence and activity. Previous microbial and geochemical investigations in shale/sand interfaces have also demonstrated higher subsurface microbial activity and biomass in the shale/sand contact (McMahon and Chapelle, 1991), fractured zones , organic-filled matrix voids (Buchwalter et al, 2015;) and zones of higher permeability (McMahon and Chapelle, 1991;Murphy et al, 1992; due to increased nutrient diffusion across interfaces.…”

Section: Lipid Biomarker Distribution and Implications Of Subsurface mentioning

confidence: 91%

“…Interestingly, PLFA analysis from these same cores showed higher concentrations of biomarkers in the Marcellus Top (Trexler, 2017, Master's Thesis, The Ohio State University). We did not expect a similar distribution for DGFA biomarkers as other factors like diagenesis, redox conditions, salinity could affect the distribution of the DGFA (by affecting the rate of cell death or rate of PLFA to DGFA conversion; Schlegel et al, 2011;Wuchter et al, 2013;Buchwalter et al, 2015;. PLFA and DGFA therefore represent different microbial communities with DGFAs being more stable and less polar as compared with PLFAs Haldeman et al, 1995;White and Ringelberg, 1998;.…”

Section: Lipid Biomarker Distribution and Implications Of Subsurface mentioning

confidence: 96%

“…( Figure 1D), and though the lability can vary widely between different shale formations (Schlegel et al, 2011;Wuchter et al, 2013;Buchwalter et al, 2015), this abundant organic matter may have served as carbon substrate for deposited microorganisms and influenced microbial dynamics before and during diagenesis. The permeability of the Mahantango Formation estimated to be 6 millidarcy (mD), higher than the 2.5 mD in Marcellus Shale Top and the Upper Marcellus Shale (Paronish, 2017), could also have influenced microbial presence and activity.…”

Section: Lipid Biomarker Distribution and Implications Of Subsurface mentioning

confidence: 99%

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Utilizing Lipid Biomarkers to Understand the Microbial Community Structure of Deep Subsurface Black Shale Formations

Akondi¹

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The deep subsurface environment has been known to host microbes as early as 1926 and has also been suggested to potentially account for as much as 50% of the Earth`s biomass. Researchers have shown that microbes alter their membrane lipid components in response to physiological stress, producing stress indicative lipid biomarkers. However, little effort has been made to understand the subsurface microbial community of the shale ecosystem which is increasingly being exploited and altered by addition of drilling and hydraulic fluids to meet our growing energy needs. Phospholipid fatty acids (PLFAs) are microbial lipid biomarkers and are found in all cellular membranes. Their presence in sediments has been used to provide evidence of living microbes while diglyceride fatty acids (DGFAs) are microbial lipid biomarkers which serve as indicators of non-viable microbes. PLFAs and DGFAs are some of the most important proxies used to determine the physiological state of microbes in natural environmental systems. Currently, techniques for the evaluation of subsurface microbial community have mostly been focused on shallow subsurface environments and aquifer settings. This stems from the lack of appropriate techniques that can monitor the deep subsurface ecosystem. Developing such techniques require pristine subsurface rock samples, appropriate instruments and an understanding of the geology and biogeochemistry of the subsurface. The goal of this dissertation is to develop understanding of microbial life in subsurface (>7000 ft.) Marcellus Shale Formation in the Appalachian Basin. The study focuses on the extraction and analyses of PLFAs and DGFAs to investigate the viable and non-viable microbial communities in these deep geologic formations. Samples used for this research were acquired from cores owned by the Marcellus Shale Energy and Environment Laboratory (MSEEL), the Department of Geology and Geography at West Virginia University (WVU), and the West Virginia Geological and Economic Survey (WVGES). A good understanding of microbial community of deep surface black shales like the Marcellus Shale, affords enormous opportunities for improving biocides in the shale energy industry, understanding subsurface microbial colonization, and engineering efforts for enhanced gas recovery. STRUCTURE OF DISSERTATION This dissertation is subdivided into three research topics. Chapter 1 investigates how buffers and biochemical amendments can improve the recovery of lipid biomarkers from the subsurface shale samples. This chapter is part of a larger investigation to optimize the yield of both viable (PLFA) and non-viable microbial (DGFA) biomarkers. The PLFA biomarkers are presented in Trexler et al. 2017 (Master's Thesis, The Ohio State University). My primary focus in the experiment was to test the performance of the different lipid extraction methods on the DGFAs. Organic amendments and buffer solutions were used to statistically account for spatial heterogeneity in geologic environments. The objective of this The Marcellus Shale Ene...

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Mapping of Microbial Habitats in Organic-Rich Shale

Cited by 2 publications

References 15 publications

Rates of Sulfate Reduction by Microbial Biofilms That Form on Shale Fracture Walls within a Microfluidic Testbed

Rates of Sulfate Reduction by Microbial Biofilms That Form on Shale Fracture Walls within a Microfluidic Testbed

Utilizing Lipid Biomarkers to Understand the Microbial Community Structure of Deep Subsurface Black Shale Formations

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