鄂尔多斯盆地富县地区长6砂岩储层特征及评价

通过岩心观察, 结合铸体薄片、扫描电镜、物性、孔隙结构等分析化验资料研究表明, 富县地区上三叠统延长组长6 段为三角洲前缘相沉积的储层。岩性主要为长石砂岩及岩屑长石砂岩; 储集空间以剩余原生粒间孔+次生粒间溶孔组合为主, 储层物性较差; 排驱压力及饱和度中值压力较高, 孔喉半径小、分选性较差, 歪度细, 溶蚀作用对改善喉道连通性有限, 孔隙结构参数总体较差; 储层质量受沉积微相和成岩作用的综合影响, 其中水下分流河道和河口坝砂体为最有利储层发育的微相; 强烈的压实- 压溶作用是形成低孔低渗的主要原因之一。利用储层物性和孔隙结构参数将长6 段砂岩划分为4 类储层, 其中Ⅰ、Ⅱ类储层是未来开发的首选储层。

Characteristics and evaluation of Chang 6 sandstone reservoir of Upper Triassic in Fuxian area, Ordos Basin

Based on core observation and the data of cast thin section, scanning electron microscope, physical properry,porosity and permeability analysis, Chang 6 sandstone reservoir of Upper Triassic in Fuxian area is analyzed. The result shows that the reservoir is delta front deposit. The lithologies of the reservoirs are mainly arkose and lithic arkose and the reservoir space mainly includes primary residual intergranular pores and secondary intergranular dissolved pores with poor physical property, high displacement pressure and high saturation median point pressure, small pore throat radius, poor pores throat sorting and fine skewness. The quality of reservoir is affected by sedimentary microfacies and diagenesis. Subaqueous distributary channel and mouth bar sand bodies are the best microfacies for reservoir development. Strong compaction and pressolution is the another factor which results in low porosity and low permeability. According to the physical properties of reservoir and pore structure parameters, Chang 6 sandstone reservoir is classified into four types. The type Ⅰ and type Ⅱ reservoirs can be taken as the major target zones for further exploitation.