CT-scan Images of 3D Natural Open Fracture Networks in a Porous Media; Geometry, Connectivity and Impact on Fluid Flow

Computed Tomography (CT) scan imaging techniques have been used on core samples to investigate the effect of natural open fractures on reservoir flow in the Snøhvit Gas Condensate Field. Firstly, CT scanning was used to describe the 3D geometrical properties of the fracture network including orientation, fracture density and fracture connectivity. Two types of fractures are observed: F1 fractures are short and stylolite related, and F2 fractures are longer crosscutting the core and without any obvious relationship to stylolites. Secondly, monitoring of single and two phase flow experiments on samples containing natural open fractures was performed under 20 and 90 bar confining pressure by using CT-scanning. 1-phase miscible flooding experiment show approximately 3 times higher flooding velocity in an open F2 fracture compared to the matrix. 2-phase flooding by gas injection into a 100% water saturated core gave early gas breakthrough due to flow in the fracture and thereafter very little water production. CT-scanning of core samples provides an effective tool for integrating geology and fluid flow properties of a porous fractured media.