煤系沉积岩多重分形维数计算及影响因素分析

为表征煤系沉积岩的孔隙结构与分形特征,选取中侏罗统页岩、泥岩和砂岩3种典型沉积岩进行了X射线衍射(XRD)分析、核磁共振(NMR)实验,运用分形理论讨论了NMR分形维数与矿物组成、物性参数之间的相互关系.结果表明:①基于弛豫时间截止值T2C,可将页岩、泥岩NMR分形维数划分为吸附孔隙分形维数DA(T2≤3 ms)和渗流...

Calculation of multi-fractal dimension of coal measure sedimentary rock and analysis of influencing factors

In order to characterize the pore structure and fractal characteristics of coal-measure sedimentary rocks, three types of typical sedimentary rocks of the Middle Jurassic shale, mudstone and sandstone were selected as the research objects. Through X-ray diffraction(XRD)analysis and nuclear magnetic resonance(NMR)experiment, the correlation between NMR fractal dimension, mineral composition and physical property parameters was discussed by using fractal theory. The results are as follows: ① Based on the relaxation time cut-off value T_2C, the NMR fractal dimension of shale and mudstone can be divided into the fractal dimension of adsorption pore D_A(T₂ ≤3 ms)and the fractal dimension of seepage pore D_S (T₂ >3 ms). ② In terms of reservoir physical properties, NMR fractal dimension D_f has a good linear negative correlation with porosity, permeability, and reservoir quality index, indicating that NMR fractal dimension can be used as an important indicator of rock physical properties. ③ In terms of mineral composition, the content of quartz and feldspar has a weak negative correlation with the fractal dimension D_f, and clay minerals have different influences on the fractal dimension due to multiple factors such as sedimentary environment, physical and chemical properties and mineral content.