鄂尔多斯盆地姬塬—堡子湾地区长_(4+5)油层成岩作用与储层评价

Diagenesis and reservoir feature of Chang_(4+5) reservoir in Jiyuan-Baoziwan Area,Ordos Basin

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,对鄂尔多斯盆地姬塬—堡子湾地区延长组长4+5油层储集岩的岩石学特征、成岩作用和物性特征进行了分析。结果表明,该储集岩为细粒的长石砂岩和岩屑长石砂岩,颗粒呈次棱角状,成分成熟度普遍较低,结构成熟度中等—较好;经历了压实、胶结、压溶和溶解等一系列成岩作用;储集岩具有低孔、低渗的特点。在以上研究基础上,结合压汞分析、孔隙组合分析,对储层进行综合评价认为,长4+5储层可分为4类,研究区以Ⅱ、Ⅲ类(中等—差)储层为主。

The reservoir rock in Chang_(4+5) of Jiyuan-Baoziwan area has been studied on lithology characteristic,diagenesis and petrophysical property with testing methods of casting thin section,X-ray diffraction,scanning electron microscope analysis,etc..It shows that the reservoir rock consists of fine arkose and litharenite lithic feldspar,whose clastic granule appears subangular,compositional maturity is low and textural maturity is medium;the clastic rocks had experienced a series of complex diagenesis as compaction,cementation,pressure solution and dissolution;and the sandstones are of low porosity and low permeability.Based on this,the reservoir is evaluated synthetically,combining with mercury analysis and pore construction analysis.The reservoir is classified into four types,and most of them are type Ⅱand type Ⅲ(medium-inferior).