After three days of sending pulses to break down the hydrates with no visible results, Welltec’s solution was rigged up. The scope of work was to restore injectivity and access through the wellbore by removing the hydrate. The first toolstring consisted of a Welltec Release Device® 218, Well Tractor® 318 and a Well Cleaner RCB 312 fitted with a 3.8” milling bit. The hydrate was tagged at 1,815 ft (553 m) where the Well Cleaner RCB was activated and milled down to 1,844 ft (562 m). A decision was then taken to remove the 3.5” stand-offs and run with the larger 4.2” mill bit in order to reduce the risk of sticking by creating a slicker tool. This solution effectively milled down to 1,997 ft (608 m) when the operation was suspended due to adverse weather conditions.
This was the world’s first milling of hydrate on e-line, proving yet another application of Welltec’s unique milling and cleaning solutions. This capability has widespread application for operators around the world as a remedial approach for this complex problem. In less than 20 hours of actual milling time 173 ft (52 m) of hydrates were removed to a depth that allowed the client to re-establish functionality to the downhole safety valve.