直罗油田长6砂岩储层微观孔喉结构特征

应用铸体薄片、扫描电镜、物性分析及压汞分析等技术手段,对鄂尔多斯盆地直罗油田长6砂岩储层微观孔喉结构特征进行了研究。结果表明:储层以细粒长石砂岩和岩屑长石砂岩为主;孔隙类型多样,主要为粒间溶孔和微孔;砂岩孔隙度平均7.64%,渗透率平均0.19×10-3μm2,属于低孔超低渗储层。不同沉积微相储层物性差异较大,水下分流河道和河口坝储层物性最好。孔隙多为小孔,孔喉中值半径平均0.078μm,属小孔、微喉道类型,分选一般,连通性较差。孔喉结构特征参数与物性的相关性研究表明,储层物性是排驱压力、中值压力、分选系数等多种因素共同作用的结果。利用储层物性、微观孔喉结构参数及单井产能等资料,将长6砂岩划分为3类储层,其中Ⅰ类、Ⅱ类是未来开发的首选储层。

Characteristics of micro-pore throat structure of Chang 6 sandstone reservoir in Zhiluo Oilfield

By thin section analysis, SEM, physical property analysis and mercury injection method, this paper studied the micro-pore throat structure characteristics of Chang 6 sandstone reservoir in Zhiluo Oilfield of Ordos Basin. The results show the reservoir is composed of fine grained and debris feldspar sandstones. The types of reservoir pores are various and are mainly intergranular dissolved pore and micro-pores. The average values of porosity and permeability of Chang 6 sandstone is respectively 7.64% and 0.19 md, belonging to low-porosity and ultra-low permeability reservoir. Property of different sedimentary microfacies are extremely different. Subaqueous distributary channel and mouth bar sand bodies are the best in property. The reservoir pore is mainly small, and the average values of median radius is 0.078 μm. The pore throat structure is the type of small pore and micro-throat with general sorting and poor communication. By comprehensive research of the relationship between characteristic parameters of pore throat structure and property parameters, it is shown that reservoir physical property is the result of driving pressure, median pressure and sorting coefficient. Using the data of the reservoir physical properties, pore throat structure parameters and single well production, Chang 6 sandstone reservoirs are classified into three types. Type I and Type Ⅱ can be taken as the major target zones for further exploitation.