大佛寺井田煤层气地球化学特征及其成因分析

Dafosi Mine Field Coalbed Methane Geochemical Characteristics and Genesis Analysis

为研究鄂尔多斯盆地西南缘煤层气的地球化学特征及成因类型,以彬长矿区大佛寺井田地面煤层气井采出的煤层气为研究对象,分析7口煤层气排采井的煤层气成分,CH4含量88.013%~97.954 8%,平均90.986%,C2H6含量0.001%~0.028%,平均0.009%,C3H8含量极少,烃类组分的干湿指数C1/C1-5为0.999 91,为特干气。碳同位素分析显示δ13CH4值介于-80.516‰^-72.352‰,平均-76.579‰,相较理论值-43.4‰要轻得多。利用气成因判别图版判定大佛寺井田煤层气为次生生物成因气。

To study on the geochemical characteristics and genesis analysis of coalbed methane in southwestern margin of the Ordos basin. Using the coalbed methane of Binchang miningareas Dafosi mine field as the research object. By analyzing 7-coalbed methane production wells of coalbed methane composition and carbon isotopes. The content of CH4 was 88.013% to 97.954 8%,with an average of90.986%. The content of C2 H6 was 0.001% to 0.028%,with an average of 0.009%.The content of C3 H8 was very small.The dry and wet index C1/C1-5 of the hydrocarbon components is 0.999 91,which is extra dry gas.Carbon isotope analysis showed that δ13 CH4 was between-80.516‰ to-72.352‰,with an average value of-76.579‰,which was much lighter than the theoretical value of-43.4‰.According to the research institute of petr-oleum exploration and development specified identify ication chart. Dafosi mine field coal-bed methane is secondary biogenic gas.