南鄱阳坳陷龙潭组树皮煤生烃潜力及油气成藏

Hydrocarbon generating potential of bark coal in Longtan Fm and oil and gas reservoiring in southern Poyang depression

周松源 徐克定 杨斌 蒋维三 彭军 刘家铎

Zhou Songyuan Xu Keding Yang Bin Jiang Weisan Peng Jun Liu Jiaduo

南鄱阳坳陷的上二叠统龙潭组煤层因富含树皮体而称之树皮煤。树皮煤的树皮体含量大于40%,同时富含基质镜质体、小孢子体等富氢组分。用生烃模拟实验方法得知树皮煤产油率很高,达到413.80 kg/t,是迄今已知的最好的煤成油烃源岩之一。通过单组分生烃模拟实验证实树皮体最有利于生成液态烃,是树皮煤生油的主要贡献者。南鄱阳坳陷的龙潭组是中国南方演化程度较低的,白垩纪盆地的叠合造就了烃源岩二次生烃、晚期成藏的地质条件。乐探1井油藏的原油经油源对比为典型的树皮煤生成的煤成油,表明在中国南方保存条件较好的地区龙潭组煤成油的勘探前景良好。

Coal in the Upper Permian Longtan Fm in southern Poyang depression is called bark coal, because it is rich in periblinite. The bark coal generally contains over 40% of periblinite, as well as abundant hydrogen-rich components, such as degradinite or vitrinite B and microsporinites, etc. Simulated experiment of hydrocarbon generation shows that the oil-generating rate of bark coal is as high as 413.80 kg/t, so it is one of the best source rocks for coal-derived oil. Simulated experiment of single component hydrocarbon generation verifies that the periblinite is the most favorable component fro generation of liquid hydrocarbons, and is the major contributor to oil derived from bark coal. The level of thermal evolution of the Longtan Fm in southern Poyang depression is relatively low compared with the other source rocks in southern China. The superimposition of the Cretaceous basin would have created the geological conditions for secondary hydrocarbon generation of the source rocks and late reservoiring. Oil-source correlation shows that the oil in the reservoirs in Letan 1 well is typical coal-derived oil generated from the bark coal, indicating that the prospects for exploring coal-derived oil in Longtan Fm is good in areas with favorable preservation conditions in South China.

10.11743/ogg20060103