鄂尔多斯盆地陇东地区延长组非主力有效烃源岩发育特征

通过油源对比确定了鄂尔多斯盆地陇东地区延长组长4+5、长6、长9暗色泥岩和长7油页岩与暗色泥岩的有效性，进一步采用热解烃指数(HCI)、可溶有机质与有机碳含量关系确定了有效烃源岩的有机碳含量下限为1.1%。以此下限值作为标准，与单井测井资料预测的有机碳含量值结合，确定了单井不同层段有效烃源岩的厚度。通过大量钻井有效烃源岩的厚度统计，确定了不同层段有效烃源岩的厚度分布特征。长4+5有效烃源岩主要分布在研究区中部，最大厚度超过60 m。长6有效烃源岩的分布中心集中在庆城-马岭一带，最大厚度超过70 m，沉积中心的厚度在20~70 m，分布范围与长7油页岩的分布较为一致。长9有效烃源岩在东北部的志丹地区，主体厚度在30～60 m。

Development characteristics of non-main effective source rocks of the Yanchang Formation in eastern Gansu Province of Ordos Basin

In this study,first,by oil-source correlation,the effectiveness of oil shale and dark mudstone was determined in the Chang 4+5,6 and 9 layers of the Yanchang Formation in the eastern Gansu Province,Ordos Basin,and next,by relation of TOC content with pyrolysis hydrocarbon index(HCI) and insoluble organic matter,the low limit of TOC content of source rock for effective expulsion was determined to be 1.1%.According to this low limit value,the thickness of effective source-rock of different layers was identified by incorporation of measured TOC and calculated TOC in single wells.Effective source-rock of the Layer 4+5 distributes mainly in the center section of the study area,over 60 m thick at the thickest point.Effective source-rock of the Layer 6 distributes in Qingcheng—Maling area,over 70 m thick at the thickest point and has a similarity with the distribution trend of oil-shale of the Layer 7.The effective source-rock of the Layer 9 with the thickness from 30 m to 60 m distributes in the Zhidan area in the northeast of the study area.