Seismic Survey of offshore Shell pipeline

mayo | environment | news report

Monday April 23, 2012 19:16

by Cara

Shell Ireland have announced that they are to carry out more seismic surveying of the offshore pipeline which is supposed to carry raw gas from the sea bed to their valve at the landfall. The survey is scheduled to take place from June 1st 2012 and although they are vague about how liong it will take, they say the survey should be completed by the end of September. If there are protests, it might not be completed at all.

Full details here: http://www.transport.ie/upload/general/13495-MN17OF2012...1.PDF

Why are they surveying their pipeline? What information are they hoping to gather, and what do they need? Will the seismic work have an effect on fish and other fauna?

Are they worried about protests while the survey is going on?

They are not providing answers to these questions, but the announcement does mention a " a third vessel" on top of the surveyr craft, which "will act as a guard vessel."

Fishermen are are warned to stay clear of the Shell survey area for the three months they are working there. There is no mention of what will happen if they choose not to.

Statement from Shell:

The seismic acquisition will comprise a two-boat operation; the M/V Ocean Pearl (call sign: LAGD6) will lay the ocean bottom cables on the seafloor and will collect all data records, while the M/V Malene Ostervold (call sign: LCIU3) will serve as the source vessel. In addition to the seismic vessels, a third vessel will act as a guard vessel.

Seismic acquisition will occur over a set of six active 12km long solid ocean bottom cables laid 400m apart on the sea bed at a depth of 350m by the M/V Ocean Pearl. At the end of each cable is a 1km lead-in section which is attached to a standalone buoy at surface. These buoys contain a power pack as well as a recording system.

Each buoy contains a radio-link with the cable-laying vessel for remote control of the buoy and for data quality control. Each buoy has a GPS receiver, so its location is well known to both seismic vessels. One by one these cables are 'rolled along', ie picked up from the northern edge of the active spread, and redeployed at the southern edge.

The M/V Malene Ostervold will be towing two seismic sources, and operating around the set of six active 12km long cables.

Radio navigation warnings will be given out daily by the Irish Coast Guard, giving the co-ordinates of the centre point of the working area for that day. All vessels will be listening on VHF Channel 16 throughout the project.

All vessels, particularly those engaged in fishing, are requested to give the seismic vessels a wide berth and keep a sharp lookout in the relevant areas.