A comparative study of free and bound bitumens from different mature source rocks with Type III kerogens

Chen, Jian; Peng, Ping’an

doi:10.1016/j.orggeochem.2017.06.014

Cited by 14 publications

(4 citation statements)

References 53 publications

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“…These observations, including our data set, can be explained by the mixing rate of the OM; the insoluble kerogen markedly predominates over the soluble bitumen in the ancient sediments. This is because soluble bitumen in the bulk rocks, particularly in the ancient sediments, can be easily altered or erased by geological processes such as burial, biogeochemical degradation, diagenesis, hydrothermal fluid circulation, metamorphism and late contamination (e.g., Chen and Peng 2017). Therefore, the determination of TOC and δ 13 C org values of ancient geological RMs using the capsule method is not recommended because the obtained data itself consists of not only insoluble kerogen but also possibly altered‐ and/or contaminated‐bitumen over the geological time.…”

Section: Discussionmentioning

confidence: 99%

Pre‐treatment Methods for Accurate Determination of Total Nitrogen and Organic Carbon Contents and their Stable Isotopic Compositions: Re‐evaluation from Geological Reference Materials

Fujisaki

Matsui

Ueda

et al. 2021

Geostandard Geoanalytic Res

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This study reports total nitrogen (TN), carbon (TC) and organic carbon (TOC) contents, as well as stable isotopic ratios (δ15NTN, δ13CTC and δ13Corg), from marine, stream and lacustrine geological reference materials (JMs‐1, JMs‐2, SBC‐1, SCo‐2, JSd‐3, JSd‐4 and JLk‐1), which can be classified into two types; modern surface, and ancient, sediments. Using this newly obtained data set, we systematically investigated the biases of three pre‐treatment methods for nitrogen and carbon measurements: (1) non‐acidification (untreated method), (2) HCl acidification in various conditions and subsequent rinsing with high‐purity water repeatedly (rinse method) and (3) in situ acidification in a gold‐coated silver capsule (capsule method). Our results showed that such acid pre‐treatments can affect both nitrogen and carbon measurements, except for the carbon data of the ancient geological RMs. Therefore, the nitrogen analysis should be conducted using untreated samples while carbon data should be obtained using the capsule method for modern surface sediments and the rinse method (6 mol l‐1 HCl acidification at 70 °C) for ancient sediments. We believe that using appropriate pre‐treatment methods is crucial to deriving new interpretations of ancient/modern environmental processes and mechanisms in the future.

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Section: Discussionmentioning

confidence: 99%

Pre‐treatment Methods for Accurate Determination of Total Nitrogen and Organic Carbon Contents and their Stable Isotopic Compositions: Re‐evaluation from Geological Reference Materials

Fujisaki

Matsui

Ueda

et al. 2021

Geostandard Geoanalytic Res

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“…Early incorporation of fatty acids, isoprenoids, sterols, hopanoids, and other biomarker precursors into the macromolecular network of kerogen/asphaltene, or absorbance onto the surface of clay minerals, or entrapped in the crystals of carbonates during early diagenesis are found to be common under geologic conditions (Xie et al 2000;Wang and Cheng 2000;Kennedy et al 2002;Farrimond et al 2003;Li et al 2008a, b;Chen and Peng 2017).…”

Section: Biogenic Interpretation Significance Of the Cm-bound Fractionmentioning

confidence: 99%

“…However, this concept has been reappraised upon the recognition of other occurrences of OM in source rocks, including claymineral interlayer-absorbed, clay-mineral surface-absorbed, carbonate-crystal wrapped, asphaltene-occluded, and asphaltene/kerogen covalently bonded OM fractions (e.g. Guan et al 1998;Xie et al 2000;Wang and Cheng 2000;Farrimond et al 2003;Cai et al 2013;Li et al 2014; Edited by Jie Hao & Jin-Gong Cai jgcai@tongji.edu.cn Snowdon et al 2016;Chen and Peng 2017), which have previously been overlooked in conventional geochemical studies. In addition to the free fraction of OM in source rocks, the remaining bound fraction could also preserve significant geochemical information concerning OM origin and maturity (Farrimond et al 2003;Ma et al 2008;Li et al 2014;Wu and Geng 2016).…”

Section: Introductionmentioning

confidence: 99%

A geochemical investigation of the free and carbonate-bound organic matter in the clay-sized fraction of argillaceous source rocks and its significance for biogenic interpretation

et al. 2018

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The molecular composition and biomarker distribution of various occurrences of organic matter in argillaceous source rocks developed in fresh and saline lacustrine environments were revealed by successive treatments of solvent extraction followed by acid hydrolysis using gas chromatography-mass spectrometry. The free fraction obtained by solvent extraction provided abundant geochemical information concerning the sedimentary environment, thermal maturity and biogenic origin, and obvious differences existed between fresh and saline lacustrine source rock samples. Our research results indicate that the carbonate-mineral-bound (CM-bound) fraction released by successive acid hydrolysis could also serve as a significant biogenic indicator, as the bicyclic sesquiterpenoids, indicative of Botryococcus braunii origin, were specifically detected in quite high abundance in the acid-soluble fraction. In addition, the light end hydrocarbons were much better preserved in the acid-soluble fraction, and elemental sulfur was only detected in the CM-bound fraction, suggesting a relatively confined environment for the CM-bound fraction, which thus could preserve additional geochemical information compared to that of the free fraction. The CM-bound fraction also exhibited discernable differences between fresh and saline lacustrine samples. Therefore, it can be concluded that comprehensive analysis of free and CM-bound fractions in the argillaceous source rocks can provide a more authentic and objective interpretation of geologic conditions.

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“…Organic-rich shales in China are deposited in marine, terrestrial, and marine-land transitional environments, with significant differences in their geochemical characteristics, reservoir properties, and gas-bearing properties. − Marine shale typically has high total organic carbon (TOC) content, with a high degree of thermal evolution and organic matter dominated by types I and II; sea-land transitional shale exhibits rapid vertical changes in TOC with some cyclicity, moderate thermal evolution, and kerogen mainly type III; terrestrial shale distribution is limited, with higher TOC at the sedimentary center, lower maturity, and dominance of types I and II1 kerogen. − According to the IUPAC, pores in shales are classified as micropores (<2 nm), mesopores (2–50 nm), and macropores (≥50 nm) . Most shale gas is adsorbed in organic nanometer pores or in the surface and interlayer pores of clay minerals. − Low-temperature CO 2 adsorption experiments can quantitatively characterize the micropore characteristics in shale. − The PSD characteristics significantly affect the gas storage capacity of shale. − Research on the genesis of PSD peaks of micropores mainly focuses on coal and transitional shales. − For example, Qu et al found that the micropores in tectonic deformation coal are lamellar pores of aromatic rings or columnar pores formed by stacking .…”

Section: Introductionmentioning

confidence: 99%

Pore Peak Types and Controlling Factors of Micropores in Different Shale Reservoirs

Nie,

Pan,

et al. 2023

Energy Fuels

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The micropores (<2 nm) developed in shale reservoirs play a crucial role in the adsorption and storage of shale gas. In this study, we investigated the organic geochemistry, mineral constituents, and micropore structure characteristics of transitional shale reservoirs in the Yangquan mining area of the Qinshui Basin, China, using total organic carbon (TOC), quantitative X-ray diffraction (XRD), and low-temperature CO2 adsorption. We analyzed the genesis and dominant factors of micropore structure characteristics in marine, terrestrial, and transitional shales. The results showed: (1) In transitional shale, the pore-size distribution (PSD) exhibited a bimodal distribution, and peaks 2 and 3 in transitional shale were mainly organic pores; the peak value of PSD is affected by sedimentary environment, the micropore volume of shale in tidal-flat facies was greater than that of shale in lagoon facies. (2) Regarding the genesis of the micropores, peak 1 was likely a false peak. The value of peak 1 in marine shale was positively correlated with the clay and Illite–smectite mixed layer (I/S), but the interlayer of Illite–smectite mixed layer was approximately 1 nm, suggesting that peak 1 was not a clay mineral pore. In terrestrial shale, the value of peak 1 was positively correlated with TOC, and we observed peak 1 in some terrestrial shale (CL-3, S-1, S-2, and S-3), suggesting that peak 1 was not an organic pore. (3) Maturity and quartz have different effects on clay minerals in different shales, and we found that maturity (R o = 1.4–2.0%) was conducive to developing clay minerals in terrestrial shale, whereas maturity (R o = 0.52–3.66%) was not conducive to developing clay minerals in marine shale; quartz was not conducive to developing clay minerals in marine and transitional shale, but it promoted the development of clay minerals in terrestrial shale.

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A comparative study of free and bound bitumens from different mature source rocks with Type III kerogens

Cited by 14 publications

References 53 publications

Pre‐treatment Methods for Accurate Determination of Total Nitrogen and Organic Carbon Contents and their Stable Isotopic Compositions: Re‐evaluation from Geological Reference Materials

Pre‐treatment Methods for Accurate Determination of Total Nitrogen and Organic Carbon Contents and their Stable Isotopic Compositions: Re‐evaluation from Geological Reference Materials

A geochemical investigation of the free and carbonate-bound organic matter in the clay-sized fraction of argillaceous source rocks and its significance for biogenic interpretation

Pore Peak Types and Controlling Factors of Micropores in Different Shale Reservoirs

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