The Challenges to Retrieve a Stuck Coiled-Tubing Pipe Without Downhole Check Valves in a High-Pressure Well: A Case Study from Argentina

Abstract

Abstract (300 words) This paper describes the lessons learned during the completion phase of an unconventional well in Argentina. Where a coiled tubing was used to perform a plug drill out campaign. The article describes the procedure of how the CT service provider followed to release a stuck pipe, the well barrier regains and its recovery. The potential solutions were analyzed by the engineering teams from both CT service provider at local and headquarter levels and the local vendors. The fact of cutting the pipe after getting stuck and unsuccessful retrieval attempts result on losing the well control barriers inside the CT pipe. There was a need to regain the well control before proceeding with the retrieval process. The use of a mechanical agents to plug the pipe was assessed, it was considered internal mechanical plugs that due to logistics will result in excessive times. Therefore, the team looked into the chemical solutions, and cement plug was also visualized but discarded due to tendency of laying down in the horizontal section of the wellbore; Finally, a high viscous resin that is fast setting time was evaluated as the optimal solution to set a plug inside the CT, which was the key to success on the safe retrieval operation. The Argentinian well was completed with 57 stages isolated by 56 dissolvable plugs over 3000 m of the horizontal section. After removing all the plugs in the horizontal section down to total depth. CT pipe was being retrieved to surface performing the final wiper trip, when it got stuck. After several unsuccessful release attempts. The decision was to cut the CT pipe at surface to allow the wireline to perform the downhole cutting. Wireline (WL) rigged up on top of the injector head and performed a tubing puncher run, 3 m below the cutting depth. Then, WL perform a second run at the free point, at a depth of 3900 m, deploying a chemical cutter to release the CT pipe. Once the CT pipe was confirmed free, the resin service company, proceed to install their high-pressure lines in the top of the injector head and proceed to pump 6.7 bbls of resin at a pump rate of 1.5 bpm, displacing it with 5 bbls of gel and 30 bbls of water leaving the bottom of the plug 500 m above of the new CT end. After the thickening time, a pressure test of the plug was done up to 8000 psi for 30 minutes followed by an inflow test of 6 hours, after the successful completion of both, the retrieval of the CT pipe was followed. This project describes the design and execution process of pumping a resin plug, without previous experience within our organization at global basis, that is suitable to regain well control on CT pipes that lost the downhole safety valves after being cut due to a stuck condition.