Geochemical conditions conducive for retention of trace elements and radionuclides during shale–fluid interactions

Mehta, Neha; Kocar, Benjamin D.

doi:10.1039/c9em00244h

Cited by 10 publications

(12 citation statements)

References 43 publications

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“…This indicates that pyrite dissolution can pose a challenge for produced water treatment. The LM-2 shale sample was comprised of 5% pyrite by weight (Pilewski et al, 2019), and pyrite is the presumptive primary source of heavy metals in the shale (Salomons, 1995;Rimstidt and Vaughan, 2003;Jew et al, 2017;Mehta and D. Kocar, 2019). Our data also demonstrate this trend and show that under acidic conditions (sample SH-HFF(-CO 3 2-…”

Section: Mineralsupporting

confidence: 69%

Effects of Carbonate Minerals on Shale-Hydraulic Fracturing Fluid Interactions in the Marcellus Shale

et al. 2021

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Natural gas extracted from tight shale formations, such as the Marcellus Shale, represents a significant and developing front in energy exploration. By fracturing these formations using pressurized fracturing fluid, previously unobtainable hydrocarbon reserves may be tapped. While pursuing this resource, hydraulic fracturing operations leave chemically complex fluids in the shale formation for at least two weeks. This provides a substantial opportunity for the hydraulic fracturing fluid (HFF) to react with the shale formation at reservoir temperature and pressure. In this study, we investigated the effects of the carbonates on shale-HFF reactions with a focus on the Marcellus Shale. We performed autoclave experiments at high temperature and pressure reservoir conditions using a carbonate-rich and a decarbonated or carbonate-free version of the same shale sample. We observed that carbonate minerals buffer the pH of the solution, which in turn prevents clay dissolution. Carbonate and bicarbonate ions also scavenge reactive oxidizing species (ROS), which prevents oxidation of shale organic matter and volatile organic compounds (VOCs). Carbonate-free samples also show higher pyrite dissolution compared to the carbonate-rich sample due to chelation reactions. This study demonstrates how carbonate minerals (keeping all other variables constant) affect shale-HFF reactions that can potentially impact porosity, microfracture integrity, and the release of heavy metals and volatile organic contaminants in the produced water.

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Section: Mineralsupporting

confidence: 69%

Effects of Carbonate Minerals on Shale-Hydraulic Fracturing Fluid Interactions in the Marcellus Shale

et al. 2021

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“…The composition of shales in the context of coal mining is well known [ 29 ] and we found ubiquist minerals such as quartz, pyrite, chlorite and muscovite. In a shale-water system, the solid-solution chemistry may be affected by numerous interactions and reactions [ 30 ]. First, when an oxic fluid comes into contact with the shale residues, these minerals rapidly undergo oxidative dissolution.…”

Section: Discussionmentioning

confidence: 99%

A Multidisciplinary Approach for the Assessment of Origin, Fate and Ecotoxicity of Metal(loid)s from Legacy Coal Mine Tailings

Gauthier-Manuel

Radola

Choulet

et al. 2021

Toxics

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Over the course of history, the development of human societies implied the exploitation of mineral resources which generated huge amounts of mining wastes leading to substantial environmental contamination by various metal(loid)s. This is especially the case of coal mine tailings which, subjected to weathering reactions, produce acid mine drainage (AMD), a recurring ecological issue related to current and past mining activities. In this study, we aimed to determine the origin, the fate and the ecotoxicity of metal(loid)s leached from a historical coal tailing heap to the Beuveroux river (Franche-Comté, France) using a combination of mineralogical, chemical and biological approaches. In the constitutive materials of the tailings, we identified galena, tetrahedrite and bournonite as metal-rich minerals and their weathering has led to massive contamination of the water and suspended particles of the river bordering the heap. The ecotoxicity of the AMD has been assessed using Chironomus riparius larvae encaged in the field during a one-month biomonitoring campaign. The larvae showed lethal and sub-lethal (growth and emergence inhibition and delay) impairments at the AMD tributary and near downstream stations. Metal bioaccumulation and subcellular fractionation in the larvae tissues revealed a strong bioavailability of, notably, As, Pb and Tl explaining the observed biological responses. Thus, more than 70 years after the end of mining operations, the coal tailings remain a chronic source of contamination and environmental risks in AMD effluent receiving waters.

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“…The release of inorganic constituents during shale–fluid interaction as a result of the hydraulic fracturing process has been mainly investigated through laboratory experiments ,,,,− and recently by exploring the geochemical and isotopic composition of flowback/early produced water (δ 34 S–SO 4 , δ 18 O–SO 4 , δ 2 H-δ 18 O of water, δ 15 N–NO 3 , δ 18 O–NO 3 , δ 15 N–NH 4 , δ 13 C-DIC, 14 C-DIC, δ 7 Li, δ 11 B, 87 Sr/ 86 Sr). ,, Most of the experimental studies have used geochemical and/or mineralogical characterization combined with batch experiments on core samples to assess major controls on element mobility including shale mineralogy, solution pH, redox conditions, ionic strength, solid to liquid ratio, and presence of specific chemical additives. Batch leachate and flowback water chemistries suggested that the oxidation of pyrite and organic matter may release trace metals/metalloids in the early stage of hydraulic fracturing ,,,,,, (Figure ). Trace metals/metalloids can also be transported in flowback/produced waters through mechanical detachment of particulate sulfide grains .…”

Section: Potential Sources Of Inorganic Contaminants In Shallow Groun...mentioning

confidence: 99%

“…In addition, U is likely to be released from the shale after reaction with HF fluid due to the dissolution of carbonate and metal oxide/phosphate minerals as well as the desorption from clay minerals . Under acidic conditions caused by sulfide oxidation and the absence of buffering minerals (i.e., carbonates), high concentrations of trace elements may result from the dissolution of Fe–Mn oxyhydroxides, which are major sinks for trace metals/metalloids . Trace element concentrations appear to decrease in the later stages of production, as produced water contains progressively more saline, strongly reducing formation waters with low metal/metalloid concentrations. , Overall, hydraulic fracturing processes are designed to ensure the development of an effective fracture network through physical modification of the rock structure and mineral dissolution, which is necessarily associated with elevated concentrations of dissolved constituents and contaminants …”

Section: Potential Sources Of Inorganic Contaminants In Shallow Groun...mentioning

confidence: 99%

Potential Impacts of Shale Gas Development on Inorganic Groundwater Chemistry: Implications for Environmental Baseline Assessment in Shallow Aquifers

Bondu

Kloppmann

Naumenko-Dèzes

et al. 2021

Environ. Sci. Technol.

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The potential contamination of shallow groundwater with inorganic constituents is a major environmental concern associated with shale gas extraction through hydraulic fracturing. However, the impact of shale gas development on groundwater quality is a highly controversial issue. The only way to reliably assess whether groundwater quality has been impacted by shale gas development is to collect pre-development baseline data against which subsequent changes in groundwater quality can be compared. The objective of this paper is to provide a conceptual and methodological framework for establishing a baseline of inorganic groundwater quality in shale gas areas, which is becoming standard practice as a prerequisite for evaluating shale gas development impacts on shallow aquifers. For this purpose, this paper first reviews the potential sources of inorganic contaminants in shallow groundwater from shale gas areas. Then, it reviews the previous baseline studies of groundwater geochemistry in shale gas areas, showing that a comprehensive baseline assessment includes documenting the natural sources of salinity, potential geogenic contamination, and potential anthropogenic influences from legacy contamination and surface land use activities that are not related to shale gas development. Based on this knowledge, best practices are identified in terms of baseline sampling, selection of inorganic baseline parameters, and definition of threshold levels.

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Geochemical conditions conducive for retention of trace elements and radionuclides during shale–fluid interactions

Abstract: Geochemical interactions occurring at the shale–water interface resulting in mobilization and retardation of solutes to produced water.

Cited by 10 publications

References 43 publications

Effects of Carbonate Minerals on Shale-Hydraulic Fracturing Fluid Interactions in the Marcellus Shale

Effects of Carbonate Minerals on Shale-Hydraulic Fracturing Fluid Interactions in the Marcellus Shale

A Multidisciplinary Approach for the Assessment of Origin, Fate and Ecotoxicity of Metal(loid)s from Legacy Coal Mine Tailings

Potential Impacts of Shale Gas Development on Inorganic Groundwater Chemistry: Implications for Environmental Baseline Assessment in Shallow Aquifers

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