海相页岩二次生烃潜力热模拟实验研究

利用热压模拟实验的方法,选取自然演化不同起始成熟度的海相页岩,系统研究了海相页岩二次生烃规律。研究表明,海相页岩二次生烃过程不是一次生烃的直接延续,生烃特征与一次连续生烃也有差异。随着二次生烃起始成熟度的增加,二次生油产率存在比一次连续生烃滞后的生油高峰,并且随起始成熟度增加位置更加向后推移,已经处于高演化阶段的海相页岩不再有二次生油高峰。起始成熟度控制二次生烃潜力,起始成熟度处于生油窗之前的海相页岩具有较高的二次生油和生气潜力,起始成熟度处于生油窗的海相页岩具有较高的二次生气潜力和一定的二次生油潜力;起始成熟度高于传统生油窗的海相页岩,二次生油能力已经很低,但是演化到一定程度还具有相当的生气潜力;已经达到过成熟的海相页岩基本上不具备二次生烃潜力。此研究完善了二次生烃的理论研究,对中国叠合盆地海相烃源岩的评价有很好的指导作用。

Secondary Hydrocarbon Generation Potential of Marine Shale Source Rocks in Thermal Modeling

Based on simulation experiments of the natural maturity marine shale samples,this article presents a brief discussion on secondary hydrocarbon generation of marine shale.The results indicate that the secondary hydrocarbon generation is not continuous with the evolution tendency of the first hydrocarbon generation of marine shale.There is a hydrocarbon generation peak during the secondary hydrocarbon generation process of low matured shale and matured shale,which is later than that of the first continuous hydrocarbon generation.The lagging is enhanced when the original maturity increases.The secondary hydrocarbon generation process of high matured shale and over-matured shale does not have a hydrocarbon generation peak.Secondary hydrocarbon generative potential is dominated by original maturity.Marine shale which has an original maturity before being oil window has preferable secondary hydrocarbon generative potential to yield abundant oil and gas.Marine shale which has an original maturity just being in oil window has preferable secondary gas generative potential and weakened secondary oil generative potential.Marine shale which has a higher original maturity than that of oil window has poor secondary oil generative potential,but still can generate considerable quantity of gas.The marine shale which has a higher original maturity than the oil-generating dead line almost has not any secondary hydrocarbon potential.This research improves the current theory of secondary hydrocarbon generation,and can be a good guidance for evaluation on marine source rock in superimposed basin in China.