Predicting the efficiency of downhole mechanical removal of one or more accreted materials from one or more wellbore walls may prevent the unnecessary consumption of resources in a wellbore fluids displacement operation. A method and system for removing accreted materials in a wellbore is provided, wherein the efficiency of mechanical removal of accreted materials may be characterized based, at least in part, on a comparison between one or more actual shear stresses exerted by a wellbore servicing fluid at one or more depths of the wellbore and one or more required shear stresses to remove the accreted materials from the depth. The one or more required shear stresses may be determined using one or more of one or more known properties of the one or more accreted materials, one or more rheology models, one or more hydraulic parameters, one or more wellbore hydraulic models, and one or more downhole conditions. To account for one or more effects of eccentricity in the wellbore, the one or more actual shear stresses exerted by wellbore servicing fluid may be determined by partitioning one or more three dimensional flow profiles into divided annular segments for individual analysis. To improve operational decision making, operators or automated processes may modify the wellbore fluids displacement operation based, at least in part, on the comparison. The comparison between the one or more actual shear stresses and the one or more required shear stresses may be used to generate a parameter that characterizes the cleaning efficiency of the wellbore fluids displacement operation.