Crude oils produced in many parts of the world contain asphaltene. Asphaltene plugging is a known cause of near-wellbore formation damage. The deposition phenomenon of asphaltene has been extensively investigated in homogenous porous media. However, we have not found any reported experimental work on asphaftene plugging in naturally or artificially fractured reservoirs. The main objective of this study is to investigate the effect of fracture characteristics on reduction of permeability by asphaftene deposition in carbonate formation.A single fracture system is made with different fracture characteristics such as porosity, permeability, and fracture angle using saw-cut limestone core samples with metallic plate. The fracture aperture was kept constant for most of the studied systems. The effect of flow rate, fracture angle, matrix to fracture permeability, asphaltene concentration, and the state of stress on the retained permeability is presented. Different fracture angle orientations of 45degrees, 90degrees, and 180degrees relevant to the flow axis were investigated. A noninvasive imaging technique-scanning electron microscopy (SEM)-was employed to visualize changes on the surface of the fracture as a result of aspheltenic crude oil flow through the system. (C) 2003 Elsevier B.V. All rights reserved.