毛管压力曲线是研究岩石孔隙结构最主要的方法之一。依据含油气泥质砂岩体积模型和HSK方程,结合半渗透隔板法、压汞法获取的毛管压力实验数据,以及CEC法测定的阳离子交换容量实验数据,分析了黏土束缚水对压汞毛管压力曲线的影响,提出一种校正压汞毛管压力曲线的方法。研究表明,对于泥质砂岩,在溶液矿化度较低且阳离子交换容量较高时,实验测量得到的压汞毛管压力曲线与半渗透隔板毛管压力曲线差别较大,即岩样黏土束缚水相对体积越高,压汞毛管压力曲线与油藏实际情况的偏差越大;应用提出的校正方法对6块不同孔隙结构岩样的压汞毛管压力曲线进行校正,中孔渗及高孔渗岩样校正后的压汞毛管压力曲线与半渗透隔板毛管压力曲线基本一致,而低孔渗岩样则不适合用该方法进行校正。
The capillary pressure curve is one of the main tools to study the rock pore structure. On the basis of an oil-bearing shaly sandstone volume model and the HSK equation, combined with experimental data of the semi-permeable membrane and the mercury injection capillary pressure curves and the cation exchange capacity, the influence of the clay bound water on the capillary pressure curve is analyzed, and a method of correcting the mercury injection capillary pressure curve is proposed. It is shown that for the shaly sands, under the conditions of low salinity of the formation water and high cation exchange capacity, the mercury injection capillary pressure curve and the semi-permeable membrane capillary pressure curve are different. The mercury injection capillary pressure curves of six samples are corrected by using the method. For the shaly sands of medium to high porosity and permeability, the mercury injection capillary pressure curves after correction can better reflect the pore structure of the actual reservoir; for the shaly sands of low porosity and permeability, the correction method proposed in this paper is not suitable.
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