延长油田坪桥油区长6油层沉积相研究

Study on sedimentary facies of Chang 6 reservoir in Pingqiao oil region

结合鄂尔多斯盆地延长期区域沉积背景,应用坪桥油区钻井岩心、岩石薄片、粒度、扫描电镜和测井资料,对研究区目的砂层组的沉积相进行了划分,分析了沉积微相平面展布特征。结果表明,坪桥油区长6油层组属于三角洲前缘亚相沉积体系,以发育水下分流河道和河口砂坝微相为主,前者顺着物源方向发育条带状砂体,在垂直物源方向上发育上平下凸的透镜状砂体,后者顺着物源方向发育上凸下平的透镜状不对称砂体,在垂直物源方向上发育上凸下平的透镜状对称砂体。纵向上不同层位沉积相及砂体展布既有相似性也存在差异。长6~1沉积时期,研究区沉积相总体自北东向南西和南部延伸,平面上砂体分布稳定、连通性好;长6~2、长6~3沉积时期,相平面分布、延伸方向和平面上砂体特征与长6~1时期相同。长6~2砂体厚度在5 m^28 m,长6~3砂体厚度在8 m^30 m,二者都是中部较厚,边部较薄,含油砂体砂地比范围在0.3~0.6。

Based on regional sedimentary background of Yanchang formation in Ordos basin and application of core,rock slice,grain size,SEM and logging data in Pingqiao area, the sedimentary facies of sand groups were divided and the distribution characteristics of sedimentary microfacies were analyzed in the area.The results show that Chang 6 formation is mainly delta front subfacies,in which tie Micro-phase are mainly underwater distributary channel and mouth bar.The sand body is mainly present bands along provenance direction in underwater distributary channel,while lenticular with flat top and bottom heave vertical provenance direction.What＇s more,the sand body is asymmetric lenticular with top convex and bottom fiat along provenance direction in underwater distributary,while symmetric lenticular with top convex and bottom flat vertical provenance direction.There are similarities and differences in the sedimentary facies and sand body distribution in different vertical layers.At Chang 61 and Chang 61-2 sedimentary period,the sedimentary facies of the study area is mainly from north east to south west and south extension,and the distribution of sand body is stable and the connectivity is good.At Chang 62 and Chang 63 sedimentary period, the distribution of the phase plane, the direction of extension and the characteristics of sand body on the plane are the same as those of the Chang 61 periods.The thickness of the Chang 62 sand body is 5 m- 28 m,while the Chang 63 is 8 m-30 re.They are thick in the middle and thin at the edge,and the sand ratio of oil sand body is in the range of 0.3-0.6.