Fracture and Vug Characterization and Carbonate Rock Classification in a Fractured-vuggy Carbonate Reservoir with CT

Abstract

This paper presents a method of characterizing fracture and vug and classifying carbonate rock with Computer Tomography (CT). Firstly, with image processing technology including image segmentation, morphological processing, skeletonization and pore characteristic parameter extraction, fractures and vugs were recognized from CT images of core samples. Secondly, Support Vector Machine (SVM) was applied for training automatic fracture and vug classification. Finally, with the characteristic parameters of fractures and vugs extracted from CT images, a new defined function of Carbonate Rock Index (CRI) was proposed, which can classify carbonate rock type. After analysis of more than 200 core samples from a fractured-vuggy carbonate reservoir of Middle East, the CRI values for matrix, vuggy and fractured carbonate rock were given in this paper. High CRI value means high fracture density, and small CRI value indicates that the carbonate rock is mainly matrix without fracture and vug. For vuggy carbonate, CRI value is in between. Therefore, CRI value can quantitatively evaluate heterogeneity due to fractures and vugs. The field application demonstrated that this method can effectively characterize fracture and vug and quantitatively classify fractured-vuggy carbonate rock.