渤南油田四区沙三段低渗透储层成岩作用及演化序列

Diagenesis and evolution sequence on low-permeability reservior of E_(s_3) in area 4 of Bonan Oilfeild

利用铸体薄片、扫描电镜、岩心分析化验等资料对渤南油田四区沙三段储层成岩作用类型、成岩演化序列、成岩阶段划分等进行了系统研究。结果表明,沙三段储层处于中成岩阶段A期,主要成岩作用类型有压实作用、胶结作用、溶蚀作用和交代作用等。压实作用是导致储层物性变差的最主要原因,胶结作用次之;溶蚀作用多形成孤立的溶蚀孔隙,一定程度上增加了储层孔隙度,但对储层渗透率的改善不大。沙三段储层经历了机械压实作用、塑性颗粒变形→泥质杂基及方解石(包括部分泥晶包壳)、铝硅酸盐的早期溶解、石英次生加大→早期碳酸盐胶结并交代石英、长石→油气大量充注→不稳定组分溶蚀形成次生孔隙、高岭石充填→晚期含铁碳酸盐矿物胶结成岩演化序列。

The diagentic facies characteristics of Es3low-permeability reservoir in Area 4,Bonan Oilfeild,such as diagenesis types,diagenetic evolution sequence,diagenetic stage division were studied synthetically using data of core observation and description,scanning electron microscope and core analysis in laboratory. The analysis results showed that the reservoir mainly developed secondary erosion pore,pore structure types are mainly belong to the medium hole-micro-fine throat. Reservoir get strong digenesis,and the main reasons leading to the poor reservoir property are compaction and cementation. Dissolution is more common,but most of dissolution pores were isolated,the configuration relationship of pore and throat was poor,increased reservoir storage space to some extent,rarely improved the reservoir seepage ability. The reservoir experienced diagenesis evolution sequence from compaction,plastic particles deformation to early dissolution of argillaceous matrix,calcite（ including part of micritic cladding）,aluminum silicate,quartz overgrowth to early carbonate cementation and replacement of quartz,feldspar and so on to oil and gas filling to volatile component dissolution,kaolinite filling to irony carbonate mineral cementation.