Mapping stress trajectories and width of the stress-perturbation zone near a cylindrical wellbore

This study reviews the analytical descriptions for stress characterization around balanced and unbalanced drill holes. The stress-trajectory patterns around cylindrical wellbores are visualized for a range of typical physical conditions. The effects of variations in far-field stress, boundary conditions, wellbore fluid pressure, and formation pressure are systematically outlined. Axially symmetric and asymmetric far-field stresses and their interaction with various wellbore pressures are quantified in diagrams scaled for universal use. The stress-perturbation zone, the region around the wellbore that is affected by a stress perturbation due to the presence of the wellbore, is delineated. Rules are formulated for practical application in wellbore-balancing studies and wellbore-stability analysis. These rules are useful for application in drilling activities aimed at the safe and effective extraction of energy resources (geothermal heat, oil, wet gas, dry gas).