The first controlled-temperature ice plug in the bend of an offshore gas trunkline has been carried out for Phillips Petroleum Co. Norway on its Norpipe A.S. platform in the German sector of the North Sea. The procedure was part of a subsea valve repair operation.
BJ Process & Pipeline Services Co. (BJ Services), Aberdeen, completed the 5-day operation which it said is significant because it allowed gas to flow continuously through a bypass line while valves were being repaired.
The ice plug was successfully formed offshore and tested to a differential pressure of 1,450 psi. Repair of two valves required only 5 days during which time gas production was operating at close to 50-60% v...