文南油田沙三中亚段8-10砂组沉积微相及沉积演化研究

Sedimentary Micro-facies and the Sedimentary Evolution for the 8-10 Sand Groups of the Middle-Sha-3 Formation in Wennan Oilfield

为弄清文南油田沙三中亚段8-10砂组沉积微相类型、空间展布及演化规律,在岩心、测录井及地震资料的基础上,用地震相约束并结合单井微相、连井剖面微相和平面微相等方法,对该区进行系统的研究。研究认为,8-10砂组主要为三角洲前缘-滨浅湖沉积体系,发育有水下分流河道、河口坝、远砂坝、前缘席状砂、分流间湾、浊积体、前三角洲泥、滨浅湖滩砂、滨浅湖坝砂和滨浅湖泥等10种沉积微相,微相的平面展布在8-10砂组3个阶段变化较大,物源主要来自东南方向,西北方向次之。随着湖平面的升降,沉积演化总体上表现为由三角洲前缘逐渐过渡到滨浅湖,再由滨浅湖过渡到三角洲前缘,最后又渐变到滨浅湖的演化过程。

To clarify the sedimentary micro-facies types,the sedimentary micro-facies distribution and evolution of the 8-10 sand groups of the Middle-Sha-3 Formation in Wennan oilfield,based on the rock core,well logging and seismic data,systematical study were carried out in this area by using the methods of single well micro-facies,tied well lateral section micro-facies and plane micro-facies. The results show that there are mainly delta front deposit and shore-shallow lacustrine deposit in 8-10 sand groups,it develops 10 types of sedimentary micro-facies such as underwater distribute channels,debouch bars,distal bars,delta front sheet sand,interdistributory bay,turbidite,pro-delta mud,shore-shallow lacustrine beach sand,shore-shallow lacustrine dam sand and shore-shallow lacustrine mud. The sedimentary micro-facies distribution differs a lot among the 3 phases of the 8-10 sand groups. The provenance is mainly come from the South-East,then north-west. Generally,with the elevation and subsidence of the lake level,the sedimentary micro-facies gradually evolved from delta front to shore-shallow Lacus,then delta front again,and finally the delta front gradually evolved to shore-shallow lacustrine.