文南油田沙三中亚段8-10砂组沉积微相及沉积演化研究

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。

Sedimentary micro-facies and the sedimentary evolution for the 8-10 sand groups of the Middle Sha 3 Formation in Wennan oilfield

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.