采用不同极性有机溶剂对取自东营凹陷地区泥页岩样品进行了逐次抽提处理,使用小角X射线散射表征技术对处理前后样品进行介孔分布特征表征和分析.结果显示,正己烷溶剂抽提效果较弱,极性较强的氯仿、甲醇/丙酮/氯仿混合溶剂及二氯甲烷/甲醇混合溶剂能够萃取出孔隙中赋存的有机质,二硫化碳/N-甲基吡咯烷酮混合溶剂由于极性太强对孔隙进行改造和破坏.经溶剂抽提后样品主峰位置分布在10 nm左右,最可几孔径值和中值孔径尺度分别介于6.7～14.5 nm和15.9～22.9 nm之间,细介孔体积百分比分布在9.5％～32.3％范围内.在泥页岩生烃阶段,粘土矿物为油气储存提供了有效储集空间,高粘土矿物相对含量的泥页岩对应的介孔分布曲线向更小孔径处集中,细介孔体积百分比与分形维数参数之间均存在明显的正相关关系,可见与粘土矿物有关的孔隙比表面趋向于粗糙化,比表面积趋大,为油气的赋存提供有利的条件.自然演化样品及热模拟样品介孔分布表征揭示了泥页岩从低成熟向高成熟热演化阶段转化的过程中,细介孔体积占介孔总体积百分比呈现出先增大后减小的趋势,而粗介孔与之相反.%Shale pores were often entirely or partially filled by organic matters in its oil window. In this study, successive solvent extraction was used to extract organic matters in shale samples from the Dongying sag by using a range of organic solvents with varying polarities and chemical structures. Small angle X-ray scattering method was used to characterize and analyze the mesoporous distribution of shale before and after solvent extraction. Results show that the extraction effect of hexane was weak. Strong polar solvent such as chloroform, the mixture of methanol, acetone and chloroform (MAC) and the mixture of dichloromethane and methanol can improve the extraction ability of organic matter. Mixed solvent of carbon disulfide and N-methyl-2-pyrrolidinone (CS2-NMP) can change and destroy pore structures. Diameter of maximum peak point of shale sample after solvent extraction was about 10 nm. The most probable aperture and average pore size were in the range of 6.7～14.5 nm and 15.9～22.8 nm, respectively. The relative percentage content of fine mesopores was in the range of 9.5％～32.3％. In the stage of hydrocarbon generation, clay minerals provide effective reservoir space for hydrocarbon. The corresponding pore distribution curve of shale with high clay mineral content was concentrated in the smaller pores. There was a significantly positive correlation between the relative percentage content of fine mesoporous and parameters of fractal dimension. The specific surface of pore related to clay minerals tended to be rough, which provided favorable conditions for the occurrence of hydrocarbon. The distribution characteristics of mesoporous in the thermal simulation and natural evolutionary samples reveal that the percentage content of fine mesoporous shows a trend of increasing first and then decreasing in the process of thermal evolution of shale. In contrast, thick mesoporous shows an opposite trend.
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