鄂尔多斯盆地丰富川油田西部探区延长组沉积演化特征研究

Study on Sedimentary and Evolution Characteristics of the Yanchang Formation in Western Exploratory Area of Fengfuchuan Oilfield in Ordos Basin

丰富川油田西部探区为多层系低渗透复合含油区,储层沉积类型复杂多样,沉积演化在很大程度上控制着油藏的富集。利用钻井、岩心、测井、生产动态等资料,深入分析了该区主要含油层系延长组长2、长4+5、长6沉积相标志、物源方向、沉积构造等特征,建立了多期沉积序列体系,并进行沉积演化特征分析。研究结果表明,延长组主要发育为三角洲沉积体系;沉积物主要通过分流河道由北东向南西输入湖盆,不同时期发育的河道展布继承性较好,充分阐明了该区延长组主要含油层段的沉积规模与沉积演化特征;在同一小层内部,河道展布的继承性较好,且组成的良好储盖组合,为油田下步勘探与寻找油藏富集有利区提供可靠保障。

The western exploratory area of Fengfuchuan Oilfield is a composite petroliferous region of multilayer and low permeability. The reservoir sedimentary is complicated. The sedimentary and evolution control the reservoir enrichment in a large part. This paper deeply analyzed the sedimentary facies, provenance and the sedimentary structure of Chang 2, Chang 4q-5 and Chang 6 in the main oil-bearing series of Yanchang formation, then multiphase system of sedimentary succession was established and sedimentary evolution was analyzed. The results indicated that Yanchang formation mainly developed delta sedimentary system; sediments were imported into Basin from northeast to southwest through distributary channel and channel distribution in different period of the development had a good inheritance which fully illustrated the deposit scale and characteristics of sedimentary evolution of Yanchang formation in the main oil-bearing segment; better inheritance of the channel distribution and a good reservoir cap assemblage in the same layer will provide reliable support for the next exploration of favorable reservoir enrichment zone.