马岭油田南部原油地球化学特征及其成藏模式

Geochemical characteristic and reservoir forming model of southern Maling oilfield

马岭油田位于鄂尔多斯盆地陕北斜坡带的西南部,是鄂尔多斯盆地发现最早的油田之一。通过对鄂尔多斯盆地马岭油田南部原油进行系统的GC和GC/MS分析,揭示原油的生物标志化合物组成特征及其来源,建立油藏成藏模式。结果显示:所分析的原油属于同一成因类型,原油有机母质为混合型,高等植物和水生生物为原油的形成作出了重要贡献;原油形成于弱还原和淡水-微咸水环境;原油成熟度高,主要是生油高峰期形成的石油;原油来自长7烃源岩,在延安组和延长组形成下生上储型或自生自储型含油组合。

Maling oilfield is located in the southwest part of the Shanbei incline, Ordos Basin, which is one of the earliest discovered oilfields in this area. Systematic analysis on the crude oil in the southern Maling oilfield of Ordos Basin by using GC and GC/MS was carried out, the biomarkers compositions and sources of the crude oil were revealed, and the reservoir forming model was established. The results show that the oil belongs to the same genetic type and the oil-forming matrixes are mixed, and higher plants and aquatic organisms make important contributions. The crude oil forms in the weak reducing and fresh water environments, and generates predominately in the peak period of oil generating with high maturity. The crude oil is derived from the Chang-7 source rocks, and forms the combination pattern of self-generating and self-accumulating or lower-generating and upper-reservoiring in Yanchang formation and Yan＇an formation.