Impact of siderite on Rock-Eval S3 and oxygen index
IR@CIMFR: CSIR-Central Institute of Mining and Fuel Research, Dhanbad
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Title |
Impact of siderite on Rock-Eval S3 and oxygen index
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Creator |
Hazra , Bodhisatwa
Singh , Deependra Pratap Singh , Pradeep K. |
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Subject |
Rock Testing
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Description |
Over the past four decades Rock-Eval pyrolysis has become a common means to type organic matter. The
modified van Krevelen diagram, using the hydrogen and oxygen indices, has become a commonly used tool for
organic matter classification. It assumes that the components used to calculate the two indices are representative
of the indigenous organic matter, which is especially the case for the oxygen index. This study provides a series of
experimental results that further characterize the impact of siderite on the hydrogen and oxygen index values,
which decrease and increase, respectively, with increasing mineral content. This work suggests that the changes
in hydrogen index values are a result of the interaction between the mineral phase and the generated hydro�carbons, where hydrocarbons may be adsorbed on to the mineral surfaces and not fully released. The increase in
the oxygen index appears to be a result of mineral decomposition and the release of CO2. The oxygen index was
found to be particularly sensitive to the presence of siderite in the sample. Siderite decomposition was found to
occur at temperatures below often published decomposition temperatures and at or below the S3 peak trapping
temperature (390 ◦C). Thus, the impact of organic carbon content and mineral interaction need to be taken into
consideration when characterizing organic matter, especially when siderite and to a lesser extent other carbonate
minerals are present. At lower organic carbon levels, organic matter will appear more gas-prone and would
suggest that the organic matter has been strongly oxidized. Although corrections have been proposed in the
literature they reduce the value of the Rock-Eval “quick” screen by adding additional analyses or data treatment.
It is further suggested that the effect may be sensitive to the early diagenetic environment as well as cation
substitution.
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Publisher |
Elsevier
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Date |
2022-06-28
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Type |
Article
PeerReviewed |
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Identifier |
Hazra , Bodhisatwa and Singh , Deependra Pratap and Singh , Pradeep K. (2022) Impact of siderite on Rock-Eval S3 and oxygen index. Marine and Petroleum Geology , 143.
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Relation |
http://cimfr.csircentral.net/2521/
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