Study on the Influence of Wellbore Engineering Parameters on Removing Filter Cake from the Well Wall to Improve Cementing Quality

In the cementing process, the drilling fluid that remains in the wellbore annulus and the filter cake on the well walls significantly impair the quality of cement bonding. This leads to reduced sealing effectiveness of the cement sheath, potentially causing issues like fluid channeling, formation loss, and collapse. Efficiently clearing the filter cake and the annulus drilling fluid is crucial for enhancing the cement slurry's bonding quality and improving the cement sheath's sealing efficiency. Wellbore engineering parameters are the primary factors affecting cementing quality. This study treats the filter cake as a Herschel-Bulkley fluid with high density and yield strength and employs CFD simulation software to develop a mathematical model for the displacement flow of isolation fluid, drilling fluid, and filter cake in the cementing annulus. It examines how variables like the number of well diameter expansion sections, well inclination angle, eccentricity, and casing rotation speed impact the displacement efficiency of the filter cake and annulus drilling fluid. The simulations reveal that as these variables increase, the displacement efficiency of the filter cake and drilling fluid decreases, except for casing rotation speed, which enhances efficiency. An eccentricity above 0.6 causes blockage in the narrow annulus, leaving over 10% of the drilling fluid trapped. The factors influencing the efficiency of filter cake displacement, in descending order, are the number of well diameter expansion sections, eccentricity, well inclination angle, and casing rotation speed. For drilling fluid displacement, the order is eccentricity, number of well diameter expansion sections, well inclination angle, and casing rotation speed. This research offers theoretical guidance for optimizing wellbore engineering parameters to improve cementing quality and ensure wellbore stability.