塔里木盆地台盆区海相油源对比存在的问题及进一步工作方向

Problems of oil-source correlation for marine reservoirs in Paleozoic craton area in Tarim basin and future direction of research

由于塔里木盆地寒武系烃源岩处于高成熟-过成熟阶段,目前钻井揭示到的上奥陶统良里塔格组烃源岩分布面积又较为局限,因此,台盆区海相原油的主力烃源岩一直存在争议。通过对原油地球化学特征研究,认为海相原油的主体为生油高峰—生油晚期阶段的产物。由于原油与寒武系烃源岩成熟度之间存在较大差异,盆地存在多套烃源岩多期成藏的特征及原油遭受二次蚀变作用,生物标志物在台盆区油源对比中受到一定的限制,今后应进一步加强对处于生油窗范围内的上奥陶统良里塔格组烃源岩特殊标志化合物演化规律及下古生界烃源岩热演化的研究。

Understanding of the major source rocks of oil in marine reservoirs in the Paleozoic craton area is always a controversial issue because of the high mature to overmature Cambrian source rocks and the limited distribution of the encountered Upper Ordovician Lianglitage Formation source rocks. Based on study of the geochemical behaviors of oils, it is believed that the oil in marine reservoirs is mainly of oil generated during oil generating peak to late generating stage. There is an obvious difference between the oil and the maturity of Cambrian source rocks, the basin is characterized by multistage reservoiring of oils generated by multiple sets of source rocks, and the oils have experienced secondary alteration, therefore the use of biomarkers for oil-source correlation is restricted in the Paleozoic craton area. Future study should be focused on the evolutionary pattern of specific biomarkers of the Upper Ordovician Lianglitage Formation source rocks that are now in the range of ＂oilwindow＂ stage and the thermal evolution of Lower Paleozoic source rocks.