Measurements on Fracture Roughness from Carbonate Reservoirs

Roughness of carbonate reservoir fractures is an important parameter for fracture geomodeling, but it is extremely elusive to measure due to shortage of direct data on fracture roughness. This paper presents first measurements on fracture roughness from the well-known Arab carbonate reservoirs in eastern Arabia. The roughness parameters (Z2, Rp, and SF) are computed from digitized profiles of fractures using a new computational technique. The results of roughness parameters are then converted into the Joint Roughness Coefficients (JRCs). Open barren fractures exhibit a quasi-normal distribution of JRCs. They mostly range between 7 and 12. Calcite-filled fractures exhibit JRCs ranging between 5 and 15. Remarkably, both types of fractures exhibit anisotropic roughness but without wall slips. Anisotropic roughness enhanced detection of open barren fractures from corresponding borehole images, signifying their potential for fluid flow. The paper discusses potentials of these results for subsurface flow, shear strengths and fracture detection.