Block-61 Rigless Method for Efficient Permanent Abandonment

Abstract

Well Abandonment is an important stage in the life of any well and in the field development plan in general. Tight regulatory requirements along with high cost made it apparent to search for more innovative methods to design and execute well abandonments more efficiently. Conventionally, well abandonment operations are performed by cementing the wellbore utilizing a drilling rig and its facilities, which is the main driver for the relatively high P&A cost. Here is where the method/initiative of "Rigless abandonment" came into play. This technique replaces the use of drilling rig with other intervention conveyance packages, resulting in a more efficient and cheaper plug and abandonment while satisfying all the regulatory isolation requirements. For a non-standard abandonment operation, the rigless abandonment initiative was a great success. All the abandonment objectives have been met and required barriers have been established while spending 73% of the planned cost only. Despite the challenges faced during the operation, the well abandonment only took 1 day longer than planned. In addition, many lessons learned have been captured to avoid recurrence in the upcoming similar jobs. In the year of 2019, a well in the northern part of bp's block 61 concession was deemed for abandonment due to poor reservoir performance. An opportunity was fore sought by the intervention team to design and execute the required abandonment in a "rigless" style. The planned process considered the use of coiled tubing unit to kill the well and place cement across the targeted Amin formation. Subsequently, utilizing the wireline service to place a plug across the packer before perforating above it. This step was to create a pathway for the cement to communicate between the A-Annulus and the tubing in the wellbore. Then, using the cement unit, the cement was reverse circulate down the annulus and up the tubing. To ensure the placement of the cement, a slickline drift run was conducted after the cement has cured, which indicated TOC at 480 m. Finally, the X-tree was removed, and the tubing and wellhead was cut at surface before performing a top-fill job to cement the remaining void up to surface. The implementation of this abandonment operation also adhered to strict safety standards. The rigid bp safety process guidelines ensured that all challenges and optimization opportunities were fulfilled in a safe manner. The purpose of this paper is to detail how the team pushed the technical envelope to introduce this methodology and share the journey of implementing a cheaper and safer well abandonment alternative.