Determination of Connectivity in Vuggy Carbonate Rock Using Image Segmentation Techniques

It is commonly understood that carbonate reservoirs hold much of the worlds' oil and gas reserves. In this study we examine a heterogeneous vuggy pore class. The vuggy pore space is imaged using x-ray computed tomography (CT). Micro-CT ($mu$CT) is used to better image parts of the interparticle (matrix) porosity. Image segmentation is applied to obtain a three-dimensional (3D) map of the vuggy pore space, which is used to determine its connectivity. We evaluate the performance of selected image segmentation techniques applied for segmenting CT-scans of vuggy carbonate rocks at varying resolutions. Computations are performed for both two-dimensional (2D) and three-dimensional (3D) image segmentation. The computations show that the methods perform well on high resolution $mu$CT scans. For a CT scan with low and non-uniform resolution they wrongly classify a large portion of the voxels. This makes it challenging to determine the connectivity. The computed porosity is, due to image resolution, underestimated when compared to measured porosity from laboratory experiments.