An offshore discharge pipe from the Corrib Gas processing plant in north Co Mayo has come loose from the sea bed.
A section of piping around 800 metres long is now floating on the surface of Broadhaven Bay.
Shell says there is no indication that the pipe has snapped and it appears at this stage that a section has come loose.
The pipe carries treated surface water from the Bellanaboy terminal out to sea.
It is understood most of the water being pumped out is rainwater that falls at the facility.
The Environmental Protection Agency has been notified and is investigating the matter.
The EPA says it does not believe there is any risk of pollution. It has no plans to send inspectors to the scene at present.
The pipe in question runs from Bellanaboy and deposits water around ten kilometres offshore.
It's not clear how it came loose but stormy conditions in recent days may have contributed.
Shell E&P Ireland has sent a number of support vessels to the area in question to assess the situation.
The company says they're examining how best to carry out remedial works to reposition the pipe onto the seabed.
It's expected that the first gas from the Corrib field will be processed later this year.
Testing work is continuing at the Bellanaboy facility.