川西坳陷西充-梓潼地区下沙溪庙组沉积微相特征

Sedimentary microfacies in the Lower Shaximiao Formation in the Xichong-Zitong region, western Sichuan depression

关键词:  沉积微相  曲流河三角洲  下沙溪庙组  西充-梓潼地区

Key words:  MicroFacies characteristics  Meandering river delta  Lower Shaximiao formation  Xichong-Zitong area

摘要:

在野外剖面、钻井取芯、镜下薄片观察的基础上，结合岩石学、沉积构造和测井曲线特征等沉积相标志，对川西西充-梓潼地区下沙溪庙组开展了沉积微相类型与特征研究。研究表明：西充-梓潼地区下沙溪庙组主要岩性为长石岩屑砂岩和岩屑长石砂岩，岩屑组分主要为沉积岩岩屑，方解石、绿泥石为主要胶结物，磨圆次棱角状，分选中等；发育了平行层理、交错层理、底冲刷沉积构造；研究区下沙溪庙组发育曲流河三角洲-湖泊沉积，曲流河三角洲在研究区主要发育三角洲前缘和前三角洲亚相，三角洲前缘水下分流河道微相是砂体主要富集环境，其空间展布主要是由北向南展布，平面上依次分布射洪、西充、南充三个砂体发育区。

Abstract:

With the help of the depositional symbols of the petroloy, sedimentary structure and well-logging curves and on the bases of the observation of the field profile, drilling core and microscopic observation, the reasearch on the sedimentary micro-facies type and characteristics were conducted for lower Shaximiao Formation in the Xichong-Zitong area of western Sichuan. The study showed that the main lithology of the lower Shaximiao Formation in the Xichong-Zitong area were feldspar lithic sandstone and lithic feldspar sandstone by the sub-angular shape, moderate sorting. The debris components were mainly sedimentary rock cuttings, calcite and chlorite were the main cements. It developed Parallel layering, staggered bedding and bottom-scouring sedimentary structures. The Lower Shaximiao Formation in the study area developed the meandering river delta-lake sediments. The meandering river delta mainly developed the delta-front and the prodelta microfacies in the study area. Subaqueous distributary channel microfacies in delta front was the main enrichment environment for sand bodies. Its spatial distribution was mainly from north to south, and the three sand body development areas of Shehong, Xichong and Nanchong were sequentially distributed on the plane.