An easy-to-implement numerical method for quantifying time-dependent mudcake effects on near-wellbore stresses

The stress state around a wellbore is critical for wellbore stability evaluation in drilling engineering. This paper presents an easy-to-implement numerical method for quantifying the effects of time-dependent mudcake thickness buildup and permeability reduction on the evolutions of stress fields around a wellbore during drilling. A common difficulty in developing dynamic mudcake models in most commercial or in-house numerical codes is the manipulation of mudcake thickness over time to represent mudcake buildup during the simulation. To overcome this challenge, a one-parameter description of both thickness and permeability variations during mudcake buildup based on an equivalent mudcake filtration study is used to facilitate model development, without compromising accuracy of the solution. The presented numerical method is verified against existing analytical mudcake buildup solution. Near-wellbore stress variation with mudcake buildup is investigated by implementing the proposed method to the commercial finite-element code Abaqus.