Wellbore instability is one of the most consequential drilling operation risks. Planning a trajectory without knowing the wellbore instability risk can be costly during operations. It is critically important for engineers to be able to validate wellbore stability coherently when trajectories are planned and be able to adjust and optimize a trajectory to minimize the risk during the planning phase. The risks of wellbore collapse in the buildup sections, if the trajectory azimuth is not optimized with formation stress orientation, could be catastrophic. Due to shale heterogeneity, the horizontal section of the wellbore also has a high risk of wellbore instability. All the wellbore instability issues can lead to non-productive time and increase the cost of well construction. The solution presented in this paper is a cloud-based, coherent trajectory planning solution with wellbore stability validation using a Mechanical Earth Model (MEM).

Detailed well planning is required to mitigate all the wellbore instability issues. This cloud-based, coherent wellbore stability validation provides an efficient way to improve trajectories by advising the best azimuth and hole inclinations to avoid wellbore instability risks. The MEM is automatically used to compute the wellbore stability (WBS) on the trajectory design. Mud weight can also be validated in the wellbore stability model based on the mud weight window provided by the MEM. In the cloud collaborative environment, all other well planning workflows, such as BHA, casing design, etc. will be validated with the designed trajectory. A case study of unconventional well planning will be presented to show how to avoid wellbore instability by choosing a different trajectory than original proposal.

In the case study, WBS was computed from a MEM whose data are acquired from wireline logging. This study mitigated the risk of wellbore instability in the curve section by changing the dogleg of the trajectory. Simultaneously, mud design, BHA design, and casing design were concurrently validated to ensure safer and better well planning. Non-productive time was avoided because of a better trajectory design and wellbore stability.

This new workflow can help operators optimize well trajectory with reduced effort and deliver high quality well planning.