From Houston (BN): Anadarko Petroleum which is the biggest operator of spars in the world is decommissioning its 10-year-old Red Hawk unit which is moored in 1,615m in Garden Banks 876, which served the Red Hawk gas field in neighbouring GB877.
Anadarko filed plans more than a year ago - in March 2013 - calling for using non-explosive severance methods, with abrasive or mechanical cutting the primary approach. The 150m-long spar - 7,200t hull and 3,600t topsides - was historic as the world’s first cell spar, a third-generation spar design that featured a bundle of tubular pressure vessels rather than the single big cylinder of the first-generation design.
Fishy theme park
Red Hawk will be towed to Eugene Island 384 and ‘reefed’, ie sunk to the seabottom to serve as an attraction for marine life. All wellheads, casing and pilings will be removed to a depth of at least 4.6m below the mud line.
US regulations require removal of structures after lease termination. The lease for GB876, where the platform is located, expired in 2012, but the lease for the field in GB877 expired in 2009.
Red Hawk was discovered in 2001 and brought onstream in 2004. Anadarko inherited it in its 2006 takeover of Kerr-McGee. With 7bcm in estimated reserves, Red Hawk was always considered a small field, thus the need for a cheaper cell spar to produce it.
Government records indicate no production at the site since 2008. Hurricane Katrina interrupted output for several months in 2005 and 2006. Production resumed, but was shut again by hurricanes in 2008. By then, it had declined sharply and appears never to have resumed. Only two wells ever produced and production peaked at 3.4mcm/d.
There appears to have been hope for more and the platform was designed for expansion to as much as 8.5mcm/d. In 2009, Anadarko drilled a third development well, but it ended up being plugged and abandoned.
The removal of the spar has been delayed from an originally planned September 2013. An Anadarko spokesman told SEN, ‘During that time, we explored a number of options for the spar, including selling it, re-using it on other projects, as well as decommissioning.’
This week McDermott announced it has been contracted to supply its crane vessel DB50 to provide accommodation and decommissioning support services, including removal of mooring lines for the spar. Mobilisation is expected during 3Q14.
The fate of the export pipeline from Red Hawk is of note. The southern 75km section of the line was converted from gas to oil and now constitutes the middle section of the three-section, 235km oil export line from Anadarko’s Lucius (31/10) spar to South Marsh Island 205. The 18in line is operated by the Southeast Keathley Canyon Pipeline Co, a 50-50 partnership of operator Enterprise and Genesis.
Re-using the pipeline segment required detaching it from the spar and moving the southern end of it - a 2.3km length - a few hundred yards to the west to link up with southernmost section of SEKCO, which like the northernmost SEKCO segment is new pipeline.