The upper Wuerhe formation of Upper Permian in District Wuba of Karamay oilfield in the northwestern margin of Junggar basin is a set of terrigenous coarse-grained clastic rocks.The main reservoir of the formation is sandy conglomerate and there are always some disputes on its sedimentary facies:alluvial fan,alluvial fan-fan delta or alluvial fan-nearshore subsea fan-fan delta.Further study on lithofacies will be benefit for accelerating the hydrocarbon exploration and development in the study area.By integrating data of core,rock thin section,lab analysis,mud log and well logging,the paper performs in-depth study on sedimentary characteristics of the formation.The study results show that the sedimentary facies of the upper Wuerhe formation in the study area is not an alluvial fan with its composite deposition system,but a set of typical fan delta depositions including 9 microfacies,i.e.,fan channel,debris flow and underwater distributary channel and so on.The paper also defines relationships between lithofacies and sedimentary microfacies.It is considered that the the physical property,oil-bearing property and formation test productivity of tractive-current sandy conglomerate are better than those of gravity-current sandy conglomerate,which could provide geological theory basis for future oil and gas exploration and development in the area.%准噶尔盆地西北缘克拉玛依油田五八区上二叠统上乌尔禾组为一套陆源粗粒碎屑岩,其优势储集层沉积相类型,一直存在冲积扇、冲积扇—扇三角洲以及冲积扇—近岸水下扇—扇三角洲的争议.深入研究其岩相,有助于研究区的油气勘探与开发.综合岩心、岩石薄片、分析化验、测井和录井等资料,对该套地层的沉积特征进行了深入研究,结果表明,研究区上乌尔禾组沉积相并非冲积扇及其复合沉积体系,而是一套典型的扇三角洲沉积,发育有扇面河道、泥石流、水下分支河道等9种沉积微相.明确了岩相与沉积微相的关系,虽同属砂砾岩岩相,牵引流砂砾岩岩相的物性、含油性以及试油产能较重力流砂砾岩岩相好,为区内后期油气勘探开发提供了依据.
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