Successful Application of Abrasive Cutting Technology with Coiled Tubing in a High-Complexity Scenario

Abstract This paper details the engineering, planning and successful execution of a complex well intervention using Abrasive Cutting Technology with Coiled Tubing (CT) to section a Milling Bottom Hole Assembly (BHA) left stuck downhole -fish-. The primary objective was the recovery of the BHA, to achieve this, it was necessary to cut it into various pieces to facilitate its recovery, every cut was made in a 4 ¾" Drill Collar with 1.25" wall thickness. This operation sets a new benchmark, marking the first documented instance in Colombia where abrasive cuts were successfully performed on Drill Collars exceeding one inch of wall thickness using 1.50" CT. The intervention was required following repeated wash over and fishing operations to try to washout the outside of the fish unsuccessfully. The technical proposal involved a two-stage approach, the first phase to gain access inside the fish, requiring initial runs to clean metallic debris generated earlier during wash over operations; and the abrasive cutting phase. The cutting phase was performed using a TRX Motor with an abrasive head pumping an abrasive slurry. The operational parameters, slurry composition and pumping time were validated with a surface yard test to ensure optimal performance during the operation downhole. This operation confirmed the reliability of the Abrasive Cutting Technology, resulting in four successful cuts on the Drill Collars. Each cut took approximately 100 minutes, an average of 110 barrels of slurry pumped at a rate of 1.1 bpm with circulation pressure between 7,000 and 8,000 psi. This case study concludes that abrasive cut using CT is a highly effective solution for challenging recovery scenarios involving large thick-walled components, providing valuable technical guidelines for future complex interventions.