莺歌海盆地东方区黄流组一段超压储层孔隙结构特征

Pore structure characteristics of Member 1 overpressured reservoir in Huangliu formation, Dongfang area,Yinggehai basin

利用铸体薄片、扫描电镜观察及压汞曲线分析等多种技术手段,对莺歌海盆地东方区上中新统黄流组一段超压砂岩储层的空间分布、物性、孔隙类型、孔隙结构以及含气性等进行了深入研究,结果表明,该层段超压储层非均质性强,中孔、高渗至低孔、特低渗储层均有出现;孔隙类型、孔喉大小是控制储层渗透率的主要因素,孔喉半径、分选系数、变异系数、歪度对渗透率影响较大;根据物性和孔隙结构特征将东方区黄流组一段储层分为Ⅰb、Ⅱa、Ⅱb、Ⅲ、It等5类,其中Ⅰb、Ⅱa、Ⅱb类储层位于有利的峰点结构区,有利于天然气聚集,为中高产能储层。

By means of several tools such as castthin sections,SEM(scanning electron micro-scope)observation and mercury intrusion curve a-nalysis,the properties of Member 1 overpres-sured sandstone reservoir in Upper MioceneHuangliu formation of Dongfang area,Yinggehaibasin,including spatial distribution,pore types,pore structure and gas concentration,were deeplyresearched.The results have indicated that:(1)this overpressured reservoir is highly heterogene-ous,with various petrophysical parameters frommiddle porosity plus high permeability to low po-rosity plus exrtemely-low permeability coexist-ent;(2)the pore type and pore-throat size arethe most important factors to control reservoirpermeability,and the pore-throat radius,sortingcoefficient,variation coefficient and skewnessmay also have great impacts on the reservoir per-meability.According to the petrophysical proper-ties and pore structure characteristics,this reser-voir can be divided into five types,i.e.TypeⅠb,Ⅱa,Ⅱb,Ⅲand Ⅰt,and TypeⅠb,Ⅱa,and Ⅱbare in the advantageous locations that are favora-ble to gas accumulation and could become the gasreservoirs with middle-high productivity.