Effect of drilling parameters on casing wear rate in ultra-deep directional well drilling

Due to great depth of directional wells and long drilling time in lower formations after cementing of intermediate casing, contact wear occurs between drilling tool and casing and hence the casing strength is reduced. Under given casing grade, the factors affecting casing wear mainly include revolutions per minute (RPM) of rotary table, penetration rate, drilling fluid density and type and bottom hole assembly (BHA), etc.The quantitative effect of each important factor on the wear rate were studied by taking Well XG-X as an example; the calculations showd that the revolutions per minute (RPM) of rotary table and penetration rate have the greatest impact on casing wear. Casing wear rate was quantitatively calculated under different penetration rate and revolutions per minute (RPM), and the relation map of penetration rate – revolutions per minute (RPM) – wear rate was generated. The penetration rate and revolutions per minute (RPM) can be adjusted within a certain range, so the penetration rate and revolutions per minute (RPM) can be properly arranged during actual drilling according to the research findings in order to reduce casing wear, improve casing life and extend the service life of oil wells.