Fracture Quantification Method with 3D X-Ray Image - Entropy-Assisted Indicator Kriging Method
H. Wang, Minou Rabiei, S. Wang, Gan Cui · SPE Western Regional Meeting · 2018
Abstract With the low porosity and low permeability in Bakken Oilfield, the fracture as principal flow channel is of vital importance. The access to micro X-ray scanning technique makes the quantification of fracture feasible. In this paper, entropy-assisted indicator kriging method is applied to segment the CT images of a shale rock sample core. This method combines the global and local information of the grayscale value. Use triple Gaussian distributions to fit the grayscale value distribution of fracture, matrix and mineral phase respectively, to obtain the global threshold. With the threshold values, the initial segmentation can be finished. Combine the initial segmentation result with entropy function to determine the boundary pixels. Then, operate indicator kriging to classify the boundary pixels. Based on the final segmentation result, the distribution of fractures and mineral phase can be observed and quantified in 3D views: There are two fractures running through the rock sample, and detailed parameters can be seen in Table 2. The volume fraction of fracture and mineral phase is 0.64% and 1.29%, respectively.