川南龙马溪组页岩孔隙分形特征

Fractal characteristics of shale pore of Longmaxi Formation in the south region of Sichuan Basin

以川南长宁—兴文地区龙马溪组页岩为对象，基于压汞实验测试结果研究其分形特征。对压汞法实验结果进行分析，采用Menger海绵模型和基于热力学关系的分形模型，计算得到川南地区龙马溪组页岩的分形维数。研究结果表明基于热力学关系的分形模型比较恰当地反应了川南长宁—兴文地区龙马溪组页岩的孔隙结构；龙溪组页岩具有明显的分形特征及较大的分形维数，分形维数在2．9337～2．9941；页岩孔隙的分形维数与TOC含量、脆性矿物含量呈正相关，而与黏土矿物含量、碳酸盐岩含量及长石呈负相关，其中黏土矿物中高岭石和绿泥石、碳酸盐岩中方解石及脆性矿物的石英对页岩孔隙结构分布特征影响较大。

According to measured results of mercury penetration tests,the fractal dimensions of shale pore structure,lo-cated in Longmaxi Formation in the south region of Sichuan Basin,were calculated by using the Menger sponge model and the fractal model based on thermodynamic relation.The result showed that the fractal model correctly responded to the shale pore structures.The shale pore structures of Longmaxi Formation was found to have typical fractal nature and bigger the value of fractal dimension,between 2.933 7 and 2.994 1;the fractal dimension value of shale pore showed positive cor-relation with the content of TOC and brittle mineral,and negative correlation with the content of clay mineral,carbonatite rock,and feldspar;kaolinite and chlorite in clay mineral,calcite in carbonate rock,and quartz in brittle mineral significant-ly affected the fractal characteristics of shale pore structure.