煤孔隙结构构造变形的压汞法和小角X射线散射表征

Mercury porosimetry and small angle X-ray scattering characterization of tectonic deformation of pore structure in coals

依托渭北煤田韩城矿区煤样,采用压汞法和小角X射线散射技术(SAXS),结合孔隙分形表征,从分形特征的角度探讨了构造变形对煤孔隙结构的影响程度。结果表明,煤的孔隙分形维数定量表征了构造煤孔隙结构的差异性变化及其非均质性。强构造变形煤具有较高的渗流孔分形维数(DHg),孔隙结构及表面非均质性较高,而渗透率较低,说明强烈构造变形所导致的复杂孔隙结构是构造煤储层低渗透的原因之一。吸附孔孔隙表面分形维数(DSAXS)随着构造变形的增强而增大,表明变形作用造成煤孔隙表面结构在微观上变得复杂。研究认为,分形维数可以指示煤中孔隙结构的构造变形程度。

Base on Hancheng Mine coal samples ,Weibei coalfield was elaborated by means of mercury porosimetry combined with small angle X-ray scattering （SAXS） based upon the fractal theory .The results show that the variation characteristics of pore structure and pore heterogeneity of tectonically deformed coals （TDC） can be represented by the fractal dimension D .Strong deformed coals have higher fractal dimension DHg ,higher heterogeneity and more complicated pore structure/surface ,and lower permeability ,indicating that the complicated pore structure resulted from strong tectonic deformation contributes to low permeable coalbed methane reservoir .With the stress strengthening ,fractal dimension DSAXS shows an increasing trend , suggesting that tectonic deformation leads to the complication of pore surface structure .Thus ,the fractal dimension can be used as an indicator of the deformation degree of pore structure .