Characterisation of carbon components and their isotopic composition in gas shales

Basu, Sudeshna; Ahmed, Jabraan; Jones, Adrian P.; Verchovsky, A. B.

doi:10.1016/j.egypro.2018.07.007

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…In our study, given the consistent δ 13 C organic of -27 in all the three samples indicating a continental source, and their δ 13 C bulk values explainable by mixing between OC and carbonate components, such a possibility is unlikely. This is supported by C/N and δ 13 C mixing relationship observed in a previous study (Basu et al, 2018). It is possible that in the shungites, the observed differential release pattern of nitrogen (with accompanying carbon) is a consequence of how the components are sited in their different forms.…”

Section: >800 • Csupporting

confidence: 80%

“…Since continental derived organic matter consists of already altered and degraded remains of the living terrestrial biomass (e.g., soil humus), it is less susceptible to further degradation and alteration as compared to marine organic matter. The organic matter for the three samples in this study is predominantly derived from continental source with any marine contribution being minor, as seen previously from C/N and δ 13 C in shale retrieved from various depth of the studied cores (Basu et al, 2018). This is corroborated by the measured δ 13 C organic ratio of ∼ −27 in all the three samples (Table 2), in agreement with expected δ 13 C of −27 for land plant organic matter, as to ∼ −20 in marine algal organic matter (Meyers, 2014).…”

Section: Source Of Omsupporting

confidence: 74%

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Stability of Organic Carbon Components in Shale: Implications for Carbon Cycle

et al. 2019

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Stability and mobility of organic matter in shale is significant from the perspective of carbon cycle. Shale can only be an effective sink provided that the organic carbon present is stable and immobile from the host sites and, not released easily during geological processes such as low pressure-temperature burial diagenesis and higher pressure-temperature subduction. To examine this, three Jurassic shale samples of known mineralogy and total organic carbon content, with dominantly continental source of organic matter, belonging to the Haynesville-Bossier Formation were combusted by incremental heating from temperature of 200 to 1400 • C. The samples were analyzed for their carbon and nitrogen release profiles, bulk δ 13 C composition and C/N atomic ratio, based on which, at least four organic carbon components are identified associated with different minerals such as clay, carbonate, and silicate. They have different stability depending on their host sites and occurrences relative to the mineral phases and consequently, released at different temperature during combustion. The components identified are denoted as, C-1 (organic carbon occurring as free accumulates at the edge or mouth of pore spaces), C-2 (associated with clay minerals, adsorbed or as organomineral nanocomposites; with carbonate minerals, biomineralized and/or occluded), C-3(a) (occurring with silicate minerals, biomineralized and/or occluded) and C-3(b) (graphitized carbon). They show an increasing stability and decreasing mobility from C-1 to C-3(b). Based on the stability of the different OC components, shale is clearly an efficient sink for the long term C cycle as, except for C-1 which forms a very small fraction of the total and is released at temperature of ∼200 • C, OC can be efficiently locked in shale surviving conditions of burial diagenesis and, subduction at fore arc regions in absence of infiltrating fluids. Under low fluid flux, C-3(b) can be efficiently retained as a refractory phase in the mantle when subducted. It is evident that the association and interaction of the organic matter with the different minerals play an important role in its retention in the shale.

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Section: >800 • Csupporting

confidence: 80%

Section: Source Of Omsupporting

confidence: 74%

Stability of Organic Carbon Components in Shale: Implications for Carbon Cycle

et al. 2019

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“…In order to evaluate the source rock potential of a shale, it is conventional to assess its depositional environment and burial depth along with its fractures and pore spaces, besides the thermal maturity and TOC content [6,15]. Study of shale from different cores, occurring as layers with different distribution of minerals and formation of bedding fractures, can help in understanding the basin evolution with respect to sea level changes, climate and/or regional thermal uplift, and subsidence [16,17].…”

Section: Directional Drillingmentioning

confidence: 99%

“…It is advisable to discard the outer 1-2 mm layer of sediment that has been in contact with the plastic or metal liner for potential contamination, especially for isotopic and elemental analyses. Extracting samples from the central portion of any drill core for geochemical analyses can minimise the superficial effects of core retrieval and contamination from handling e.g., [15,60,[62][63][64]. Hammering should be avoided as it can damage the core.…”

Section: Samplingmentioning

confidence: 99%

Best Practices for Shale Core Handling: Transportation, Sampling and Storage for Conduction of Analyses

Basu

Jones

Mahzari

2020

JMSE

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Drill core shale samples are critical for palaeoenvironmental studies and potential hydrocarbon reservoirs. They need to be preserved carefully to maximise their retention of reservoir condition properties. However, they are susceptible to alteration due to cooling and depressurisation during retrieval to the surface, resulting in volume expansion and formation of desiccation and micro fractures. This leads to inconsistent measurements of different critical attributes, such as porosity and permeability. Best practices for core handling start during retrieval while extracting from the barrel, followed by correct procedures for transportation and storage. Appropriate preservation measures should be adopted depending on the objectives of the scientific investigation and core coherency, with respect to consolidation and weathering. It is particularly desirable to maintain a constant temperature of 1 to 4 °C and a consistent relative humidity of >75% to minimise any micro fracturing and internal moisture movement in the core. While core re-sampling, it should be ensured that there is no further core compaction, especially while using a hand corer.

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“…Here, we describe a new experimental system, developed to simulate the deep subsurface sidewall core retrieval process 21 , 22 and to accurately measure gas volumes extracted from natural high-pressure shale samples. Our experiments recreate the subsurface conditions for pressure (P) and temperature (T) of deep commercial shale formations; subsequently, the core lifting process is applied to the cores by controlled decompression.…”

Section: Introductionmentioning

confidence: 99%

Direct gas-in-place measurements prove much higher production potential than expected for shale formations

Mahzari

Mitchell

Jones

et al. 2021

Sci Rep

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Shale gas exploitation has been the game-changer in energy development of the past decade. However, the existing methods of estimating gas in place in deep formations suffer from large uncertainties. Here, we demonstrate, by using novel high-pressure experimental techniques, that the gas in place within deep shale gas reservoirs can be up to five times higher than that estimated by implementing industry standard approaches. We show that the error between our laboratory approach and the standard desorption test is higher for gases with heavier compositions, which are of strongest commercial interests. The proposed instrumentation is reliable for deep formations and, provides quick assessment of the potential for the gas in place, which could be useful for assessing hydrocarbon reservoirs, and the potential for geological carbon sequestration of a given formation.

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Characterisation of carbon components and their isotopic composition in gas shales

Cited by 5 publications

References 6 publications

Stability of Organic Carbon Components in Shale: Implications for Carbon Cycle

Stability of Organic Carbon Components in Shale: Implications for Carbon Cycle

Best Practices for Shale Core Handling: Transportation, Sampling and Storage for Conduction of Analyses

Direct gas-in-place measurements prove much higher production potential than expected for shale formations

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