Subsea safety valves (SSSV) are safety-critical when a well has sufficient reservoir pressure to flow naturally. Among other things, they are used to secure offshore wells during hurricanes to prevent pollution in the unlikely event the wellhead sustains damage. They are tested regularly and must be reliable.
While testing a SSSV in one of its wells in the Campeche Bay, a major Latin American Operator discovered scale deposits that prevented the SSSV from sealing shut. The operator was looking for an alternative mechanical solution, since pumping acid into its wells had not been effective. A downhole tractor service provider approached the operator and after carefully studying the case, presented the wishbone honer brush design run on a well tractor and electric line to repair the valve in situ and avoid costs associated with mobilizing a rig and removing well components. It was the first time this technology was used successfully for this application.
The operator deployed the cleaning equipment in August 2011 and performed the work in 18 hours operating time. The SSSV tested successfully on the following day and the well was returned to production. The operator estimated that the selected technology saved more than a week of deferred production at 7500 BOPD and direct costs of rig mobilization. The wishbone honer brush tool run on a well tractor and electric line proved to be the alternate solution they were seeking and it is now the operator’s preferred technology for this application.
This paper will present the operational challenges as well as the results of this successful, rigless cleaning operation on an important producing well.