湖相碳酸盐烃源岩热解生烃特征

Hydrocarbon-generating characteristics of lacustrine carbonate rocks

湖相碳酸盐岩的生烃研究较为薄弱,但具有重要的勘探与理论意义。选择酒西盆地青西凹陷2种岩性的湖相烃源岩——泥岩和泥质白云岩进行热解模拟实验,对比分析了2种不同岩性湖相烃源岩的生烃过程,并建立了它们各自的生烃模式。实验结果表明,泥质白云岩生烃高峰明显晚于泥岩,即甲烷产量峰值较泥岩后移,液态烃的生烃高峰出现在高温演化阶段,具有晚期生烃的特点。对于湖相碳酸盐岩生油盆地,2套湖相烃源岩的生烃模式不同,生烃高峰期亦不同,门限深度不能一概而论。

The study on the hydrocarbon-generating of lacustrine carbonate rocks has very important significance in exploration and theory. Meanwhile, it is very weak compared with the marine carbonate rocks and the muddy source rocks. Through the kinetics simulation experiment by using lacustrine mudstone and argillaceous dolomite, the hydrocarbon-generating process of these two different lithology limnetic source rocks are researched comparatively. Based on this experiment, the hydrocarbon-generating models of these two rocks are established, respectively. The experiment result shows that the hydrocarbon-generating peak of the lacustrine carbonate rocks is later than that of the lacustrine mudstone. The peak gas generation of the lacustrine carbonate rocks is relatively late. Moreover, the hydrocarbon-generating peak of liquid hydrocarbon from the lacustrine carbonate rocks occurs at the stage of high-temperature evolution. This indicates that late hydrocarbon generation is the characteristic of the lacustrine carbonate rocks. It is considerable that the oil threshold depths of these two source rocks are different in the lacustrine carbonate rocks petroleum basin.