收稿日期: 2017-12-17
修回日期: 2018-02-01
网络出版日期: 2018-03-10
基金资助
Study on hydrogen isotopes of hydrocarbon gases generated during hydrous pyrolysis of herbaceous marsh peat
Received date: 2017-12-17
Revised date: 2018-02-01
Online published: 2018-03-10
为了认识成岩水介质对热解煤层气氢同位素的影响,对草本泥炭进行了加水和无水热解模拟实验,研究了热解产物烃类气体的氢同位素组成及其差异性与演化规律,发现成岩水介质对热成因烃类气体氢同位素组成具有显著的影响。在泥炭中加入氢同位素值高于泥炭形成环境水的水,其模拟实验产生的烃类气体氢同位素值显著增高;并且从泥炭连续热解至RO值为 5.5%时,加水泥炭模拟实验使热解甲烷、乙烷和丙烷平均δD值分别增加了7‰、2‰和66‰。随着模拟温度升高,生成的烃类气体的δD值增大。认为加水模拟实验使热解烃类气体氢同位素值增高起因于水氢与有机氢同位素的交换。建立了具有较高δD值的淡水参与下热解烃类气体δD值与RO值的数学模型,以及不同烃类气体之间δD值的数学模型。这些研究成果为成岩水介质参与下草本沼泽成煤物质热解煤层气的成因研究提供了科学依据。
段毅,吴应忠,赵阳,曹喜喜,马兰花 . 草本沼泽泥炭加水热解产物烃类气体氢同位素特征[J]. 天然气地球科学, 2018 , 29(3) : 305 -310 . DOI: 10.1176/j.issn.1672-1926.2018.01.015
In order to understand the influence of diagenetic water medium on the isotopic compositions of thermogenic coalbed gas,hydrous and anhydrous pyrolysis experiments were performed on herbaceous marsh peat.We studied the hydrogen isotopic compositions,their differences and evolutionary law of hydrocarbon gases generated during the pyrolysis of the samples.It was found that the diagenetic water medium has a significant effect on the hydrogen isotopic composition of the hydrocarbon gases.Adding water with higher hydrogen isotopic value than peat-formed environmental water,the hydrocarbon isotope value of the hydrocarbon gas produced by peat pyrolysis was significantly higher.At pyrolysis intervals from peat to vitrinite reflectance values (RO) of 5.5%,the average δD values of pyrolytic methane,ethane and propane produced by hydrous peat pyrolysis experiment increased by 7‰,2‰ and 66‰,respectively.As the simulated temperature increased,the δD value of the generated hydrocarbon gas increased.It was considered that higher hydrogen isotope value of hydrocarbon gas produced by hydrous peat pyrolysis experiment resulted from the isotope exchange between water hydrogen and organic hydrogen.The relationships between RO values and the hydrogen isotopic compositions of the hydrocarbon gases generated by hydrous peat pyrolysis and the hydrogen isotopic relationship between the hydrocarbon gases were established.These results may provide a basis for studying on the genesis of coalbed gas formed by herbaceous marsh coal-forming material with the participation of diagenetic water media.
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