黔北地区海陆交互相龙潭组泥页岩孔隙分形特征

Fractal Characteristics of Shale Pore from the Marine-terrigenous Facies Longtan Formation in Northern Guizhou

基于分形理论和方法,以钻井岩心泥页岩样品低温液氮吸附试验数据为基础,分析黔北龙潭组泥页岩样品的孔隙分形特征,运用分析FHH模型计算了吸附孔分维值D,并探讨了分形维数与孔隙结构、有机碳含量(TOC)、岩矿物等之间的关系。研究表明:样品孔隙以中孔为主,孔径主要分布在20 nm以下;分维值介于2.683~2.912之间,吸附孔分形特征明显,反映了泥页岩孔隙结构复杂和非均质性强的特征;分维值与BET比表面积、平均孔直径、BJH中值半径呈较好的相关性,与最大吸附量、有机碳含量和石英亦有较好的相关性,而与黏土矿物相关性不明显。

Based on fractal theory and methods and the results from the experiment of low temperature nitrogen adsorption in Northern Guizhou,the pore fractal Characteristics of the Shale samples derived from Longtan Formation in Northern Guizhou were analyzed.With the FHH fractal model,the absorption pore fractal dimension values D were calculated and the relationship between fractal dimension values and pore parameters,TOC,shale composition were quantitatively studied.Results show that the pores were mainly distributed in mesopore under40nm,and the fractal characteristics of shale adsorption pore are obvious that fractal dimension value varies in2.683~2.932,which reflecting the complex pores structures and strong heterogeneity.The relationships between fractal dimension values and BET specific surface area,the average pore radius,BJH median radius are correlated,and the relationships between fractal dimension values and maximum adsorption capacity,TOC content and quartz are also correlated,while indirectly correlated with clay mineral.