Wellbore trajectory optimization for horizontal wells: the plan versus the reality

Horizontal wellbore profile and trajectory optimization without hole problems are considered the most essential part in well planning and design. In this paper, a long radius horizontal well was trajectory optimized by selecting horizontal profile, kick off point (KOP), horizontal turn trajectory, vertical turn determination, and mud weights. After that, in order to design 3D profile, the Minimum Curvature Method (MCM)was used for survey determination. Moreover, the best well orientation was selected based on rock mechanics and wellbore stability so that the optimum trajectory could be drilled without instability problems. Real horizontal well passed through 5 targets: NRQ 255 6H-1, NRQ 255 6H-2, NRQ 255 6H-3, NRQ 255 6H-4, and NRQ 255 6H-5 are studied. The planned trajectory has found the same as real trajectory until 9 5/8” casing is landed to true vertical depth (TVD) =7230 ft. and measured depth (MD) =7343.6 ft. However, during drilling 8.5’’ hole, it was impossible to continue drilling due to the drillstring being stuck because of caved shale and hole pack off. Wellbore trajectory was redesigned and selected after building new wellbore stability and geomechanical stress models using logging while drilling (LWD) data. A 6’’ sidetrack hole was successfully drilled and hit the five targets horizontally.