通过实验室测得的岩心孔隙度和渗透率数据的分析,证实了对于缝洞型强非均质碳酸盐岩储层,岩心的取样偏差导致实验分析数据的不稳定,从而造成其无法体现储层物性的全貌及非均质性,对于发育裂缝的碳酸盐岩样品,常规测井和核磁测井的测量结果也难以体现出裂缝对储层物性的影响.提出了一种利用二维岩心CT扫描图像处理直接获取孔隙、裂缝和溶洞的信息分析方法,通过计算二维图像上的孔隙、裂缝和溶洞的面积来估算孔隙度和渗透率,并进一步评价储层非均质性.利用岩心分析、核磁测井以及CT扫描图像解释3套数据集计算的变异系数和洛伦兹系数,以及不同采样间隔的CT扫描图像获得的物性差异分析了储层的非均质性,并对比了各种方法的异同点和有效性.认为从二维岩心CT扫描图像中提取的岩石物性数据集是缝洞型碳酸盐岩储层非均质性分析的一种有用的、可靠的资料来源.

Fracture-vug carbonate reservoirs have strong heterogeneity, and the heterogeneity have a significant effect to oilfield development. Many data are available for reservoir heterogeneity evaluation. However, it is necessary to evaluate the adaptability of different data sets, which could bring different and unreasonable results for heterogeneity analysis. By analyzing of porosity and permeability of cores measured in the laboratory, it is confirmed that for the fracture-vug carbonate reservoirs with strong heterogeneity, the core analysis data could not reflect the heterogeneity of the secondary pore distribution, because the laboratory measurements are unstable due to sampling deviation of the core. For carbonate samples with fractures, the measurement results of conventional logging and nuclear magnetic logging also could not reflect the effect of fractures on reservoir physical properties. A method for directly obtaining information of pores, fractures and vugs through edge detection of core CT scanning images by using Sobel operator is proposed. Then the area of pores, fractures and vugs could be calculated at different sampling intervals, which could be considered approximately equal to the porosity. Therefore, the permeability is estimated by calculating the distribution of pores, fractures and vugs on CT scanning images at different sampling intervals, and the reservoir heterogeneity is further evaluated by using the permeability data calculated from CT scanning images. The heterogeneity of the reservoir is analyzed by using the variation coefficients and Lorentz coefficients calculated by three sets of data sets from core analysis, nuclear magnetic logging and CT scanning image interpretation, as well as the difference of physical property obtained from CT scanning images at different sampling intervals, and the similarities and differences and effectiveness of various methods are compared. It is considered that the rock physical property data set extracted from the 2D core CT scanning image is a useful and reliable data source for the heterogeneity analysis of fracture-vuggy carbonate reservoirs.