基于恒速压汞技术的致密砂砾岩储集空间刻画

Application of Constant-Rate Mercury Penetration Technique in Studying the Microscopic Pore Space of Tight Sandy Conglomerates Reservoir

利用恒速压汞技术分析松辽盆地徐家围子断陷沙河子组致密砂砾岩的储集空间特征,明确孔隙和喉道的大小、分布、连通性以及与储层物性的关系。结果表明,砂砾岩孔隙半径的分布100~200μm,形态呈单峰状,孔隙半径与孔隙度、渗透率均呈较弱的正相关关系,表明孔隙对物性具有一定控制作用,但不是很显著。喉道半径分布的离散程度较高,随着渗透率的增大,喉道半径的分布区间和峰值呈增大趋势,但不超过5μm。喉道半径与储层孔隙度的关系不显著,与储层渗透率明显呈现正相关关系,即喉道半径对砂砾岩储层的致密和渗流能力具有绝对控制作用。砂砾岩储层孔喉连通性差,孔喉比分布在20~600。有利储层的喉道半径多数大于0.5μm,孔喉比多数小于200。

Constant-rate mercury penetration was used to study the microscopic pore space of tight sandstone reservoir in Shahezi formation of Xujiaweizi depression, and distribution of pore and throat and their control on reservoir physical were analyzed.The results show that the distribution range of pore radius is mostly 100-200μm and is barely influenced by reservoir physical. The correlation of pore radius and reservoir physical is not significant, thus the pore radius has the secondary control on petrophysical property. Throat radius varies greatly with the reservoir permeability, and the distribution range of throat radius tends to increase with the reservoir permeability. However, the distribution range of throat radius is no more than 5μm in value. Throat radius is correlated with porosity slightly, while it is strongly influenced by permeability, indicating that throat is the main factor that controls reservoir. The pore-throat connectivity of sandy conglomerate samples is not well, with pore throat ratio ranging form 20-600. The throat favorable for reservoirs is mainly over 0.5 μm in radius and less than 200 in pore throat ratio.