Coil Tubing Recovery

COIL TUBING RECOVERY

Background

The platform was located on a large gas producing field in the Central North Sea. The wells were beginning to water out and in an attempt to increase production the decision was made to run Coil Tubing Velocity Strings. During the first string installation, a runaway occurred which resulted in the shear seals being closed on the coil to secure the well. The platform had a drilling rig installed but it was currently in a tepid stack. A cost and risk analysis identified Hydraulic Workover as the most efficient way to regain well integrity.

Objective

The objective was two part: Firstly, to regain the use of the tree by clearing the coil across the tree. Secondly, to clear the coil to below the safety valve and regain use of the safety valve.

Planned Execution

  • HWU was utilized due to the availability of competent personnel and was cost effective in comparison to re-starting the rig.
  • The tree was to be cleared using a mechanical rotating external cutter.
  • Tension was then to be applied to the coil and an e-line cutter deployed to below the safety valve.
  • Cut was to be made and coil recovered to surface.

Results

  • Successfully cleared tree with external cutter.
  • Technical challenges were the residual bend in the coil that resulted in the inability to get the e-line cutter to depth.
  • Unit successfully rigged up inside a derrick for the first time.
  • Great team work from all parties involved.
  • Operation was conducted to and at a level above and beyond customer expectation.