Abandonment operations often include casing cutting or milling prior to cement placement so that an effective cement to formation seal can be created. The cutting and milling activities introduce significant amounts of swarf into the wellbore which can often setting out in the BOP cavities. This can damage seals and can even compromise functionality.
To address this problem, a UKNS operator approached Coretrax for a solution. The operator was already suffering from significant NPT due to weather, however they were often missing weather windows to run the BOPs due to the length of time it would take to clean the BOPs between wells. Additionally, the operator was very aware that the rig crew were being exposed to hazardous swarf that has the potential to cause serious injury.
Coretrax created our CX-BOP Cleaning String using a combination of high strength magnets and high pressure jetting nozzles. Whilst the high pressure jets dislodge debris, the magnets can then capture the ferrous material so it can be removed from the wellbore and recovered at surface.
The CX-BOP Cleaning String was first utilized after the environmental barrier was placed and the rig was waiting on cement. During this time, the BOPs were jetted and 56kgs of swarf was recovered from the wellbore. When the BOPs were recovered to surface, the amount of swarf visible in the cavities was minimal. By recovering this swarf, significant rig time was saved and the risk of injury to rig personnel was significantly reduced.
