基于分形理论的毛管压力和电阻率指数相关性研究

以岩石孔隙结构的分形理论为基础,建立毛管压力与电阻率指数的理论模型,并进行半渗透隔板岩石电阻率-毛管压力联测试验对模型进行验证分析。结果表明:对于所用的泥质砂岩岩心,当其孔隙度分布在12.9%～18.1%,渗透率分布在(0.313～21.196)×10-3μm2时,毛管压力与电阻率指数呈幂指数关系,其拟合指数与孔隙结构指数关系较好;含水饱和度变化率与电阻率指数的关系图与孔喉半径分布直方图具有一定的相似性。毛管压力是表征孔隙结构的重要参数之一,在利用岩电试验资料进行测井储层评价时,须充分考虑孔隙结构对岩石电学性质的影响。

Research on correlation between capillary pressure and resistivity index based on fractal theory

The theoretical model of capillary pressure and resistivity index was established based on fractal theory of pore structure.The semi-permeable plate resistivity-capillary pressure experiments were conducted to verify the relationship between capillary pressure and resistivity index.The results show that the capillary pressure and resistivity index has a power function relationship and the fitting exponent between capillary pressure and resistivity index has a nice coherence with pore structure index for shaly sand cores studied in the experiment when its porosity ranges from 12.9% to 18.1% and permeability ranges from 0.313×10-3μm2 to 21.196×10-3μm2.The correlation chart between water saturation variation ratio and resistivity index is similar with pore throat radius distribution histogram.Capillary pressure is one of the most important parameters for pore structure characterization.The impact of pore structure on conductivity property should be considered when using litho-electrical experiments data for well logging analysis and formation evaluation.