In situ high temperature ESR measurements for kerogen maturation

Bakr, M.; Aoki, Masahiko; Sanada, Yuzo

doi:10.1016/0146-6380(91)90095-2

Cited by 19 publications

(17 citation statements)

References 19 publications

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“…It would appear that the observed process is a specific feature of terrigenous organic matter. A further argument for the recombination of C 6+ moieties with the kerogen structure might be the observation of Bakr et al (1991), that the amount of free radicals, initially generated by cracking reactions, decreases (their stage 2) after the initially increasing trend. The authors assign this behaviour to radical recombination reactions with no related weight loss, a feature which fits well with the observations reported here.…”

Section: Recombination Reactionsmentioning

confidence: 97%

Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea

Erdmann¹,

Horsfield²

2006

Geochimica et Cosmochimica Acta

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Section: Recombination Reactionsmentioning

confidence: 97%

Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea

Erdmann¹,

Horsfield²

2006

Geochimica et Cosmochimica Acta

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“…The evolution of N g with kerogen maturation has been discussed extensively (Morishima and Matsubayash, 1978;Marchand and Conard, 1980;Aizenshtat et al, 1986;Seehra et al, 1986;Fowler et al, 1987;Bakr et al, 1991;McTavish, 2003;Larsen et al, 2005Larsen et al, , 2006Lewan et al, 2006). The different evolutions of N g with vitrinite reflectance between three kerogen types are shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

“…Qiu (1994) tested the ESR spectra of coal sample with 5% and 25% content of pyrite, and there was almost no difference between the two ESR spectra. However, the pyrite may enhance and accelerate the process of free radical formation (Bakr et al, 1991). In addition, Kerogens that contain large amounts of organic sulfur form radicals thermally at much lower temperatures than low sulfur kerogens (Lewan and Ruble, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…There are other solvents to extract kerogen, such as benzene/methanol, pyridine, etc. and different solvents will result in the differential ESR spectrum at lower maturity of organic matter (Bakr et al, 1991). However, we want to preserve the natural state of kerogen structure in this study.…”

Section: Discussionmentioning

confidence: 99%

“…Early studies revealed the presence of stable free radicals in coal with the ESR method (Ingram et al, 1954;Uebersfeld et al, 1954). Since then, many ESR studies have documented the structure, maturation and reactivity of carbonaceous materials, such as coal, petroleum and kerogen (Retcofsky et al, 1968;Durand et al, 1977;Marchand and Conard, 1980;Tissot and Welte, 1984;Larter, 1988;Bakr et al, 1991;Trudy et al, 1995; Diaz et al, 2000;Bandara et al, 2005;Dick et al, 2005;Walters et al, 2007;Pancost et al, 2008;Tiem et al, 2008). The structure of kerogen was investigated by ESR method and attempts to correlate ESR parameters of kerogen with its maturation have been reported (Pusey, 1973;Marchand and Conard, 1980;Bakr et al, 1988;McTavish, 2003;Larsen et al, 2005Larsen et al, , 2006Lewan et al, 2006;Sun et al, 2006).…”

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confidence: 99%

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Temperature and Time Effects on Free Radical Concentration in Organic Matter: Evidence from Laboratory Pyrolysis Experimental and Geological Samples

Qiu

et al. 2012

Energy Exploration & Exploitation

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The free radicals concentration (N g ) of organic matter evolves with the temperature, time, kerogen types and other factors for the individual kerogens. This paper focuses on the N g evolution of immature type I and II kerogens and a type III coal under the laboratory pyrolysis temperature and heating time. The experiments were carried out in a closed system pyrolysis at an isothermal reactor in the temperature range from 300 to 500°C over 30 to 480 minutes. A temperature time index (TTI) is applied and the TTI values were calculated in order to indicate the pyrolysis temperature and time at which the kerogen had experienced. Some equations were established to show the relationship between the TTI and N g of type I, II and III kerogens, based on the tested data from laboratory anhydrous pyrolysis experiments of three kerogen types and geological type I kerogen samples. However, the evolution of free radicals concentration with temperature and time shows some differentials between different types of kerogen samples. This paper also discusses the different TTI-N g relation of type I kerogen between laboratory pyrolysis experimental and geological samples, which are collected from core samples with depth interval of 1137 to 4090.6 m. The TTI-N g equation from pyrolysis experimental samples should be calibrated by the data from geological samples when the equation is to be extended to the geological timescales. As the free radical concentration in organic matter is strongly maturity dependent, the relationship between TTI-N g may prove to be a valuable method to study paleotemperature of sedimentary basins.Keywords: Free radicals, Vitrinite reflectance (R o ), Kerogen, Temperature Time Index (TTI), Thermal history, Pyrolysis experiment INTRODUCTIONFree radicals are units with an unpaired electron in organic matter. Kerogen, the portion of sedimentary organic matter not soluble in organic solvents, is believed to have analogous structures in which numerous aromatic rings form angularly conjunctive aromatic sheets, with substituents (such as paraffinic side chains) attached at the sheet margins (Tisssot and Welte, 1984). Thermal cracking of paraffinic chains from the kerogen molecules initially forms alkyl and kerogen free radicals (Wang and Chen, 1988). Smaller alkyl radicals are highly unstable and are thus rapidly quenched by hydrogen extracted from the surrounding environment. However, the larger kerogen free radical is stabilized by the extended aromatic system and can be stable through geological time. Although there have been various structure models for different types of kerogen at different level maturity, the main chemical structure of kerogen include the core structures and linkages. Kerogen is defined to be a complex geopolymer and a heterogeneous macromolecule comprised of randomly cross-linked core structures that may be aliphatic, naphthenic, aromatic and/or heteroatomic . The chemical structures of kerogen and the free radicals reactions have been studied widely (Siskin et al., 1995;Sun and P...

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Thermogenic Formation of Hydrocarbons in Sedimentary Basins

Mahlstedt¹

2018

Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate

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In situ high temperature ESR measurements for kerogen maturation

Cited by 19 publications

References 19 publications

Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea

Enhanced late gas generation potential of petroleum source rocks via recombination reactions: Evidence from the Norwegian North Sea

Temperature and Time Effects on Free Radical Concentration in Organic Matter: Evidence from Laboratory Pyrolysis Experimental and Geological Samples

Thermogenic Formation of Hydrocarbons in Sedimentary Basins

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