鄂尔多斯盆地东缘煤储层渗流孔隙分形特征

基于压汞试验,分析了鄂尔多斯盆地东缘14个矿区56件煤样储层孔隙的分形特征,通过分维数与煤储层渗透性的比较,得出孔隙体积分维数与煤储层渗流孔隙的渗透性关系.结果表明,煤储层压汞孔隙分形尺度为孔直径86 nm～1 000μm,体积分维数2.75～3.24,在区域分布上呈自北向南降低的趋势,与煤变质程度、灰分、矿物含量呈负相关关系,与水分、中孔含量及视孔隙度(>5%)呈正相关关系.储层渗透性的分形表征与分形维数、分形尺度及分形孔隙的分布连通性多因素相关,但在储层孔隙率较低的情况下,分形孔隙的分布连通情况对渗透性起决定性作用.

Fractal Characteristics of Coal Reservoir Seepage Pore, East Margin of Ordos Basin

Based on mercury injection experiments, the pore fractal features for 56 coal samples come from 14 mine areas in eastern margin of Ordos basin were studied. The relationship be-tween the pore volume fractal dimension and the permeability of seepage pore were proposed. The results show that the fractal scaling is 86 nm-1 000 μm (diameter) through the pressur-ized mercury fissure analysis. The pore volume fractal dimension is from 2.75 to 3.24, which has a decreasing tendency from north to south. The negative connections with metamorphic grade, ash and mineral content exist, while positive connections with moisture, apparent po-rosity (>5%) and mesopore volume percentage content exist. The fractal features describing the permeability should contain fractal dimension, fractal scaling and connectivity of the seep-age pores. The distribution and connectivity of the seepage pores is the primarily factor while the lower porosity.