裂陷盆地岩浆活动对煤层气的富集作用——以辽河、阜新盆地为例

中国东部中、新生代裂陷盆地在成盆期或成盆期后大多都发生过不同程度的岩浆活动。以煤、油、气共生的辽河盆地东部凹陷和我国首次在矿井中发现、研究、开发煤层气藏的阜新盆地王营井田为例，系统地阐述了火山活动在古近系沙河街组三段对褐煤、长焰煤和气煤在平面及垂向分布的控制，进而导致各赋煤区气源条件的不同；估算了王营井田在区域深成变质过程释放甲烷气的基础上，接触变质作用所形成的附加甲烷量；指出由于岩浆侵入形成了天然焦和高变质裂隙煤，使煤层物理性质及储集能力发生了大的变化；强调了岩墙等不同产状的岩浆侵入岩体对煤层气的封闭作用。最后得出岩浆活动是中国东部中、新生代裂陷含煤盆地煤层气富集乃至成藏的重要因素之一的结论。

Effects of magmation on the enrichment of coalbed gas in rifted-basins in East China: Examples from the Fuxin and Liaohe basins

Most of the Mesozoic and Cenozoic rifted basins in East China experienced magmation to some extent during or after the basin formation. Taking the eastern sag of the Liaohe basin where coal, oil and gas resources coexist and the Wangying borefield of the Fuxin basin where coalbed gas was first discovered, researched and developed in China as examples, we systematically discuss the control of volcanism on the lateral and vertical distribution of brown coal, flame coal and gas coal in the third member of the Paleogene Shahejie Formation and on the gas source conditions of each coal region. Both the methane released in the process of regional plutonic metamorphism and the additional methane generated by contact metamorphism are calculated. The physical properties and storage capacity of the coal beds changed greatly due to the formation of blackcoal and highly metamorphosed crevice coal from igneous intrusion. The sealing capacity of intrusions with various occurrences such as dikes is highlighted. It finally concludes that magmation is one of the major factors influencing the enrichment and pooling of coalbed gas in the Mesozoic and Cenozoic rifted coal basins in the eastern part of China.