基于CT图像分析探究孔洞型碳酸盐岩储层分维值与微观结构参数关系

Study on Fractal Dimension and Microstructure Parameters of Vuggy Carbonate Reservoirs Based on CT Images

碳酸盐岩储层非均质性强,发育溶蚀孔洞等孔隙结构,其固相颗粒级配良好,直径跨度范围约为三个量级,且为连续分布,具有统计自相似性和标度不变性,为严格意义上的固相分形多孔介质,与之伴生的不同形态、不同尺度的孔洞累积数量与直径分布遵循幂律关系;基于CT图片处理统计4块震旦系碳酸盐岩储层岩心的孔隙累积数量与直径分布,确定存在分形特征的无标度区间,计算分维值大小,结果表明固相颗粒配级越好,尺度分布范围越大,孔隙结构越复杂,分维值越大;分析计算了分维值与微观结构参数中的孔隙度和渗透率的定量关系,可为室内实测孔渗值的校正提供参考,也为探究多孔介质的分形特征提供了一个新的角度和方法。

Carbonate reservoirs contain denudation vugs generating strong heterogeneity,and have well-graded solid particles whose diameter of span is about three orders of magnitude,which meet continuous distribution and self-similarity,belonging to porous medium of solid phase fractal,and there has power law relationship between vugs from different shapes and scales cumulative quantities and diameters distribution; scale-invariant intervals and fractal dimensions could be obtained from CT images that have been undergone a series of processing for 4 cores,which proves the more well-graded and complicated,the greater fractal dimensions; quantitative relation between fractal dimensions and microstructure parameters,such as porosity and permeability,which would provide references for measured values and a new perspective and methodology to the study of fractal features for porous medium.