【摘要】 以松辽盆地为例,通过热模拟实验及热模拟产物组分和稳定碳同位素分析,对极低级浅变质岩(泥板岩)的生烃能力及产物进行研究。研究结果表明,产物烷烃气碳同位素组成偏重,大量生气阶段(450~550℃)δ13C1值为-31.4‰~-22.3‰,同位素序列为1δ3C1<1δ3C2<1δ3C3或1δ3C1<1δ3C2、1δ3C3<1δ3C2,共性特征为1δ3C1<1δ3C2、δ13CCO2<-10.0‰,显示为有机成因天然气;导致碳同位素组成偏重的原因是浅变质岩中的生气母质具有较重的碳同位素组成。高温作用可能使碳同位素系列部分倒转,但机制尚不明确。根据模拟实验气态烃产率探讨了浅变质岩的生气潜力,认为肇深6井4 115.47 m泥板岩生气能力达到86.4 m3/t,预测松辽盆地基底浅变质岩在长垣以东地区生气强度能够达到20×108m3/km2,具备形成一定规模气藏的生烃条件。图6表4参31更多还原

【Abstract】 By taking pyrolysis experiments and analyzing composition and carbon isotopes of pyrolysis products,the hydrocarbon generation potential and products of very low-grade epimetamorphic rocks were studied.The carbon isotopes of alkane gases are relatively heavier,when the reactant was in an abundant gas generation stage(450–550 ℃),e.g.the δ13C1 were-31.4‰–-22.3‰,carbon isotope series showed δ13C1<δ13C2<δ13C3 or δ13C1<δ13C2,δ13C3<δ13C2,and the common feature being δ13C1<δ13C2 and δ13CCO2<-10.0‰,indicating the biogenic features.These less negative carbon isotope compositions inherit from heavy carbon isotope of organic matters in these rocks.High temperature may result in carbon isotopes of alkanes partly reversing and the mechanism has been discussed in this paper,but it isn’t clear yet.The reservoir-forming potential of very low-grade epimetamorphic rocks is discussed from the aspect of hydrocarbon generation.Gas generation potential of muddy slate at a depth of 4 115.47 m in Well Zhaoshen 6 reached 86.4 m3/t.It is predicted that the hydrocarbon generation intensity can be 20×108m3/km2 in areas of eastern Daqing placanticline where very-low grade epimetamorphic rocks are distributed,capable of forming gas pools of certain scales.更多还原