Restoring Well Integrity on a Damaged Wellhead: Lessons Learned in an Unconventional Intervention

Abstract

Abstract While performing a mast-up rig move on a recently completed well, the spreader beam of the substructure hit the X-mass Tree (Christmas tree), which in turn caused the X-mass tree and the wellhead to tilt by 21 degrees. Due to the visible damage to the wellhead and tree, as well as the unseen damage to all the tubulars downhole, an unconventional approach was required to intervene and remediate this well so that the operator could proceed with either restoring the well or going for a Plug and Abandon (P&A) option. The primary stage of operations was to assess the damage inflicted, which revealed that the crossover that connects the casing hanger to the 13-3/8″ casing, had been bent due to the impact. It was imperative to make the Christmas tree and Wellhead assembly vertical before conducting any operations. The assembly was anchored on the traveling block, and then a horizontal force was applied to restore the wellhead to a vertical position. To ensure tubing accessibility, a gauge cutter run was performed; however, it could not pass through the bent area, which was just below the tubing hanger. To perform any remedial/intervention operations the first and foremost step was to fabricate a support structure to be able to bear the axial weight of Blow Out Preventers (BOP) since the wellhead was already damaged. The tubing was recovered by mechanically backing it off and pulling it out of hole. While pulling out the tubing to surface, it was discovered that the tubing was damaged as well due to the impact. The casing was then assessed for any damage, and the Original Equipment Manufacturer (OEM) were engaged to determine the mechanical properties of the casing for any further production from this well. A dedicated bit trip followed by a Polish mill was performed to check for any damage caused to the 7″ casing caused by the incident. Complete casing integrity was restored, and a new completion was installed to bring the well back online. The innovative ideas used to restore the well's integrity and return it to production could serve as a case study for future wells that face the unexpected scenario of the x-mas tree or wellhead tilting and bending the casing and tubing strings. Rather than abandoning the well, the lesson learned in this case can be applied to recover such wells and produce from them.