不同渗透率岩芯孔径分布与可动流体研究

为了解释通过压汞毛管压力曲线计算原始含油饱和度偏大的原因，对所选择的样品分别进行核磁共振、高速离心以及常规压汞实验，并将实验结果进行对比，分析了不同孔径区间核磁可动流体饱和度和压汞进汞饱和度的区别并解释了其原因。实验结果表明：超低渗储层岩芯（0.1 mD < K < 1.0 mD）的压汞进汞饱和度要明显大于核磁共振可动流体饱和度，分析认为出现这种差别的主因是小喉道所控制的核磁可动流体体积与压汞进汞量差别较大造成的；特低渗储层岩芯（1.0 mD < K < 10.0 mD）的压汞进汞饱和度可能依然高于核磁共振可动流体饱和度；渗透率较大的储层岩芯（渗透率K>10.0 mD）的总核磁可动流体饱和度与压汞进汞饱和度相差不大，压汞进汞体积与核磁可动流体均主要分布在半径大于1.00 μm的喉道区间中。

Study on Influence of Permeability and Distribution of Pore Diameters in Rock Cores on Measurement of Mobile Fluid Saturation

To understand why the calculation of original oil saturation through mercury injection capillary pressure (MICP) curves always yields excessively large values, we measured the mobile fluid saturation of a set of selected samples using nuclear magnetic resonance (NMR), high-speed centrifugation, and conventional mercury injection experiments. Comparisons were then performed to analyze how the mobile fluid saturation in different pore diameter ranges differed from the MICP-measured value of mobile fluid saturation, to reveal the underlying causes of these differences. The experimental results indicated that, in ultralow-permeability reservoir cores (0.1 mD < K < 1.0 mD), MICP-measured saturation was significantly larger than NMRmeasured mobile fluid saturation. Our analysis revealed that this was caused by differences in the quantity of injected mercury and the volume of mobile fluids (as measured by NMR), because of the restrictions imposed by small pore throats. In lowpermeability reservoir cores (1.0 mD < K < 10.0 mD), MICP measurements of mobile fluid saturation may still result in larger values than the corresponding NMR measurements. In reservoir cores with high levels of permeability (K > 10.0 mD), the difference between the MICP-measured saturation and the total mobile fluid saturation was relatively small. In this case, it was found that both the injected mercury and mobile fluids were mainly distributed within pore throats with radii greater than 1.00 μm.