Formation Damage Analysis Due to Filtrate Invasion in Deviated Wells: A Numerical Approach

Abstract

During production, drilling, completion, stimulation and work-over operations, the formation is exposed to several types of fluids which have high tendencies to impair and impact gas and oil productivity by reducing pore throat size and relative permeability. Therefore, it is desirable to accurately characterize filtration process during these operations. A mathematical model was developed describing the mechanism of formation damage in deviated wells. Rate of mud cake build up, cumulative filtrate volume and depth of invasion into the formation at different angles of inclination were determined. The model employed numerical approach rather than the conventional analytical method to solve the equations developed using the fully implicit discretization scheme. The effect of filtration on the angle of deviation was determined and this should help in planning and allocation of drilling time in order to reduce formation damage.  Also the analysis shows the result of infiltration on cake thickness and filtrate volume at the early, middle and late time of permeation into the formation. The model was validated with the previous analytical model. Results showed that the previous conventional analytical models developed overestimate the formation damage when compared to the numerical model.