基于分形与核磁共振测井的储层孔隙结构表征与分类

Pore Structure Characterization and Classification Based on Fractal Theory and Nuclear Magnetic Resonance Logging

基于核磁共振测井与分形理论,对鄂尔多斯盆地彭阳地区长8储层孔隙结构多重分形特征进行了分析。根据核磁共振实验反映的岩石孔隙结构差异,将研究区岩石孔隙结构类型分为大孔占优、中孔占优、小孔占优3类;针对岩石不同类型孔隙结构的核磁共振T2谱计算奇异强度α、多重分形维数Dq、多重分形谱f(α)等多重分形参数,探索了孔隙结构类型与多重分形参数之间的关系。研究表明,核磁共振T2谱多重分形参数与孔隙结构类型有关,可用多重分形参数划分孔隙结构类型。利用该方法对核磁共振测井数据进行处理,基于多重分形维数图像和多重分形谱宽对不同类型孔隙结构进行可视化和定量化表征,实际应用效果较好,表明核磁共振T2谱具有多重分形特征,利用核磁共振T2谱多重分形参数能够较好地评价不同井段孔隙结构类型。

The pore structure of reservoirs in Pengyang area of Ordos basin is studied based on multifractal theory and nuclear magnetic resonance(NMR)logging.According to the pore structure reflected in the nuclear magnetic resonance experiments,the types of rock pore structures in the study area are divided into three categories:macropores,mesopores and micropores.The singularity intensityα,fractal dimension Dq,and fractal spectrum f(α)of the multifractal parameter are calculated for the NMR T2 spectrum of different types of rocks.The results show that different types of pore structure have significant differences in the multifractal parameter values of the NMR T2 spectrum.Multifractal parameters can be used to classify the pore structure type.The method is used to process NMR logging data.Based on multifractal dimension image and multifractal spectrum width,different types of pore structures are visualized and quantitatively characterized.The practical application effect in NMR log profile is good,which shows that multifractal is a property of NMR T2 spectrum.The multifractal features and parameters of NMR T2 spectrum can be used to evaluate pore structure types effectively.