Increasing Extended-Reach Capabilities Through Wellbore Profile Optimization

Abstract

Abstract While some extended reach wells appear to be drilled with comparative ease, others to deeper targets and lower departures can present all sorts of difficulties. A simple two dimensional model is presented specifically to illustrate the interaction between the key variables associated with an extended reach well: kick-off point, locked-in inclination, build-up rate and tortuousity. The analysis indicates that the maximum achievable drillable depth depends upon inclination and has a minimum in the region of 45-55 degrees. Maximum reach may be obtained by, wherever possible, adjusting the kick-off depth to achieve a locked-in inclination of 70-75 degrees. Drillable depth is not very sensitive to initial build-up rate. Excessive tortuousity can severely limit drillable depth and should therefore be used as an objective measure of directional drilling contractor performance.