鄂尔多斯盆地涧峪岔油田长4＋5油层成岩作用与储层评价

利用岩石铸体薄片鉴定、X射线衍射分析、扫描电镜分析等测试手段,对鄂尔多斯盆地涧峪岔地区延长组长4＋5油层储集岩的岩石学特征、成岩作用和孔喉特征进行了分析。结果表明,该储集岩为以浅灰白色细粒长石砂岩、粉砂岩为主,颗粒呈次棱角状,成分成熟度较低、结构成熟度中等-较好,粒度分选性较好;砂岩储集层在埋藏成岩过程中发生的成岩作用有压实作用、胶结作用、交代作用和溶蚀作用,且主要处于晚成岩A期—晚成岩B早期;孔隙类型以粒间孔为主,溶孔次之,喉道类型主要为微-细喉道,以细喉道为主,造成渗透率低,形成特低渗、超低渗型储层。根据延长组地特低渗透储层划分方案,利用本次研究中的多种参数和各种分析方法,将储层划分为三类。评价结果表明,研究区长4＋5储层以中低孔、特低渗—超低渗储层为主。

Diagenesis and Reservoir Evaluation of Chang4+5 Reservoir in Jianyucha ioi field, Ordos Basin

The reservoir rock in Chang4＋5 of Jianyucha area has been studied on lithology characteristic,diagenesis and property texture with testing methods of casting thin section,X-ray diffraction,scanning electron microscope analysis, etc..It shows that there reservoir rock consists of grayish-white fine arkose and siltstone,whose clastic granule appears subangular,compositional maturity is low,textural maturity is moderate-better and its particle sorting is better. The sandstone reservoir has experienced from late diagenesis A stage to late diagenesis early of B stage and a series of complex diagenesis as compaction,cementation,metasomatism and dissolution;Pore types are dominated by intergranular pore,and secondary dissolution pore,main minimal-fine throat and fine throats are caused by low permeability,ultimately formed the extra-low permeable and ultra-low permeable reservoir.According to the division scheme of ultra-low permeable reservoir of Yanchang formation,Chang4＋5 reservoir is divided into three categories by multi-parameters and kinds of analysis methods,evolution result shows there is mainly medium-low pore reservoir and ultra-low permeability-ultra-low permeability type Chang 4＋5 reservoir in studied area.