Retrieval of lower completion results in WCI
IOGP Well Control Incident Lesson Sharing #24-9
During retrieval of a lower completion an influx was swabbed into the well. There was no possibility to circulate below swellable packers. In your review, please consider what failures in your operations would lead to implementation of contingency procedures. Are your potential failures identified, mitigated and are contingency procedures in place?
This incident is one of many which seem to be affected by risk normalization during operations in depleted/not naturally flowing reservoirs. Well control standards are frequently lowered in these situations, with the consequence that equipment and competence are insufficient to prevent escalation of an incident.
The Wells Expert Committee/Well Control Incident Subcommittee believes that this incident description contains sufficient lessons to be shared with the industry. We further encourage the recipients of this mail to share it further within their organization.
What happened?:
Following the inability to run the lower completion (SAS c/w 2 swellable packers + 1 mechanical zonal isolation packer) to the targeted setting depth, it was decided to pull the completion.
After the packer (full hole) has entered the casing, tripping volume anomalies were noticed, interpreted as swabbing effect - estimated volume swabbed: 8 cubic metres. No possibility to circulate below the packers.
Decision is taken to continued to pull - pumping out - compensating swab by replacing volume of mud below packer.
As packers assembly reached top of hole (casing hanger) - BOP was shut in and each packer was stripped-up to mitigate any possible trapped pressure / effluent underneath. When the last packer passed above the 9-5/8" Casing Hanger, a pressure build up was noticed and stabilized at 270 psi.
Situation was assessed and packer could be stripped out to rig floor and laid out.
A XO was installed to DP string in order to strip double float valves assembly back into the well in order to circulate the influx out using Driller's method.
What Went Wrong?:
Swab kick, hole not filled properly.
Pumped back the extra volume recovered not understanding that the volume below the packer was not filled with 1.52SG mud but light effluent.
2 Swellable Packers inflated increasing drags and risk of swabbing.
Lack of clear procedure to POOH completion - scenario not considered (MoC).
Corrective Actions and Recommendations:
Add contingency procedure in completion program for POOH the completion.
Reinforce chain of command protocol in case of anomaly (ex swabbing).
safety alert number: 372
IOGP Well Control Incident Lesson Sharing http://safetyzone.iogp.org/
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