The Influence of Drilling Parameters on Casing Wear in Ultra-Deep Directional Well

During the drilling of horizontal wells, extended reach directional wells and ultra-deep directional wells, there is always a long drilling period after the cementing of intermediate casing. The rotation, tripping, flexing by bit weight and transverse vibration of the drilling pipes causes casing wear during this period which lowers the internal pressure strength and the collapsing strength of casing. At a certain casing grade, the drilling parameters that affect casing wear mainly includes rotary speed, rate of penetration (ROP), mud density, mud type, and bottom hole assembly. Until now, quantitative influences of each important factor on casing wear have not been studied. The authors addressed this need by studying the XG-X well, and the results indicate that rotary speed and ROP affect e wear the most. The wear of the well's casing at different rotary speeds and different rates of penetration was computed and the relationship of ROP to rotary speed to wear shows that the parameters are controllable within a certain scope. The two drilling parameters can be rationally selected to reduce the wearing during the actual drilling process so as to lengthen casing life and oil well service life.