鄂尔多斯盆地三叠系延长组沉积有机相

Sedimentary organic facies of the Triassic Yanchang Formation in the Ordos Basin

根据沉积有机相基本的有机岩石成分组成,结合三叠系延长组地层的沉积相和富集及分散有机质的地球化学特征,将鄂尔多斯盆地三叠系延长组煤和烃源岩划分为陆地森林(沼泽)有机相(A)、湿地森林(沼泽)有机相(B)、湿地草本混生(沼泽)有机相(C)、覆水草本(沼泽)有机相(D)、异地残殖(漂浮沼泽)有机相(E)和开阔湖盆藻质有机相(F)6类沉积有机相。其中,A和B相成煤,F相为油气源岩,而C,D,E相具有成油和成煤的共性。通过不同有机相有机质的热解实验,分析了各有机相的油气生成潜力,提出沉积有机相是综合评价煤、油、气、油页岩等多种有机可燃矿产共存共生的有效方法,并运用沉积有机相对鄂尔多斯盆地延长组煤和烃源岩的成烃方向及转化能力进行了综合判识。

Coal and hydrocarbon source rocks in the Triassic Yanchang Formation in the Ordos Basin were studied to identify their sedimentary organic facies by combining the basic organic rock compositions of sedimentary organic facies with the sedimentary faices and the organic geochemical characteristics of enriched or dispersed organic matters in the Yanchang Formation. The result indicates that there are six types of organic facies： the terrestrial forest （bog） organic facies （A）, the swamp forest （bog） organic facies （B）, the swamp-marsh forest （bog） organic facies （C）, the marsh （bog） organic facies （D）, the allochthonous residual （float bog） organic facies （ E）, and the open lake algae organic faces （F）. Among them, A and B generate coal, F generates hydro- carbons, while C, D and E generate both hydrocarbon and coal. The hydrocarbon generating potential of each or- ganic facies was analyzed through Rock-Eval experiments. It is suggested that the study on sedimentary organic facies is a useful method in evaluating the paragenesis of various types of combustible organic minerals, including coal,oil, gas, and oil shale. A comprehensive evaluation of the hydrocarbon-generation trends and convertion ability of the coal and hydrocarbon source rocks in the Yanchang Formation was also carried out by adopting knowledge concerning the organic sedimentary facies