A client was working through their abandonment program when they encountered a difficult well. The well had been experiencing issues for several years. Back in 2012, a PLT logging toolstring and 8760ft of logging cable was left down hole. When the time came to abandon the well, they were unable to kill the well due to the blockage. They were unable to bullhead the well, however the reservoir could still flow gas to the surface. In the end, WG003 was mobilised to carry out well intervention by snubbing, retrieve the 7" completion and then kill the well.
Fishing the lost wire through the completion could not be done because of a restriction in the well from 2015. Additionally, the wire was likely in poor condition.
Through Tubing Cement was too risky since the attempt to bullhead failed, there was a high risk of locking up the tubing with cement.
Since there was 8760ft of cable down hole, milling with coil tubing would have been extremely challenging. There would also be the potential of milling the tubing and gassing up the A annulus.
Upon rigging up WG003, a pressure build up test was conducted. A bullhead at 5000psi was attempted and then lubricating and bleeding. Neither of these methods cleared the blockage. The continued lubricating and bleeding lead to 150ft Hydrate plug forming in the completion, between the top side and sea bed. To dissolve the hydrates, methanol was snubbed into the well.
Two options now presented themselves. Either, pull off the packer with gas still in the tubing and revers circulate or snub in with a mill and mill away the blockage.
It was decided to pull of the packer and reverse circulate in the hope of killing the well. A nine ram BOP stack was rigged up with three main elements: Conventional rams, stripping rams and functional rams. The top of the tubing and the annuls was filled with 70/30 TEG to prevent further hydrate forming. A spear was snubbed in to engage the tubing hanger.
The tubing hanger was unseated and the completion lifted off of PBR. This immediately established communication with the A annulus and lead to substantial losses. The tubing was closed to minimise u-bending and maximise fluid to the reservoir.
Eventually, the tubing was opened to bleed off trapped gas. With all the pressure bled off and the pump rate steady, the tubing was pulled. The tubing was pulled out to the blockage. The tubing was then punched below the blockage and fluid was circulated to confirm the tubing was gas free.
After the well was killed 7150ft of 7" completion tubing was recovered. A 9-5/8" scraper was run in made up with the remaining completion tubing. A 9-5/8" E-line bridge plug was set at the base of the Horda formation and the 9-5/8" cement was logged. The unit was demobbed and the well handed back for final abandonment plug.