Global First 18.625 and 13.375-in Level-2 Casing-While-Drilling Successful Deployment through Open-Hole and Cased-Hole Sidetracked Wellbores to Isolate Severe Unstable Zones

Abstract

AbstractDuring non-productive time (NPT) such as stuck pipe incidents, reducing the operational time and associated cost of the trouble mitigation should always be the goal. Therefore, the engineering team searched for new and innovative ways to reduce the NPT when stuck pipe incidents happen, and successfully utilized an existing technology in a new way not yet performed on a global basis.In seldom incidents drilling or tripping through unstable zones (especially when drilling through sticky shales and loose sandstone zones charged with downhole faults/fractures) with complete loss of circulation, severe tight spots, stalling tendencies, hard backreaming, etc. might be experienced. In the worst case, the pipe might get stuck and cannot be freed. The engineering team investigated several options to allow drilling and casing off the trouble zones in such incidents, while reducing the NPT in the same time. Sidetracking through open-hole and/or cased-hole whipstock, then utilizing level-2 casing-while-drilling technology to drill and case-off the instable zones was the best cost effectient option.Successful deployment of level-2 16-in × 13-⅜-in casing-while-drilling (CwD) technology through an 18-⅝-in cased-hole sidetrack whipstock and level-2 22-in × 18-⅝-in CwD technology through open-hole sidetrack led to drilling and casing off severe unstable sections in two separate wells in different areas of interest. The level-2 13-⅜-in CwD utilization to drill and case-off trouble zones through cased-hole sidetrack was the global first. The level-2 18-⅝-in CwD utilization to drill and case-off trouble zones through open-hole sidetrack was the country first. Both led to significantly reducing the non-productive time (NPT) resulted from the stuck pipe incidents in a cost effective manner. Extensive engineering simulations, technical limits, and risks assessment were set to insure flawless execution. During the job execution, the drilling performances were constantly monitored. The engineering simulations are updated using the actual parameters to ensure accurate measurements of the accumulated fatigue while being rotated to preserve the casing due to exposure to high dogleg severity (DLS) in the sidetracked wellbore. Furthermore, the hydraulics are optimized real-time to ensure hole cleaning without further increase in the equivalent circulating density.Even with no prior global experience of the utilization of this technology through such operation, the pursuit of the technical limit was to reduce the NPT as much as possible. The technical paper will highlight the planning steps, challenges, detailed engineering simulation, risks mitigations and engineered solutions, and the successful results of the deployment of level-2 CwD runs through sidetracked wellbores.