Decommissioning Process Optimization Methodology

Abstract The over 4,500 idle wells and 783 idle structures in the U.S. federal waters of the Outer Continental Shelf at the beginning of 2011 were increasing the risk of contamination to the environment as these assets aged, while at the same time the cost to decommission these assets was on the rise. During the hurricane seasons of 2005 and 2008 over 175 structures and 1,000 wells were damaged or toppled to the sea floor by wind and storm surge that further exposed the risk, increased the cost of decommissioning and made underwriting the repair or replacement of these assets no longer affordable to many operators. Renewed pressure on operators to decommission idle infrastructure sooner rather than later was brought forth by the issuance of new guidelines by regulators in the form of a Notice to Lessee. These new guidelines now require operators to decommission idle wells and supporting structures as soon as possible, but no later than 5 years after they become no longer useful for producing oil and gas in paying quantities. With the cost of decommissioning and regulatory pressure increasing, many operators began seeking new and better decommissioning methods that could get more work done, safely and at a lower cost. Employing the newest technologies, a new, optimized decommissioning methodology was made possible. The size and capabilities of a newly designed and constructed 335 class self-elevating, self-propelled, marine vessel (liftboat) allowed a departure from the traditional method of performing decommissioning work-steps sequentially, one-after-the-other, to a new method of performing the majority of work-steps concurrently in just one spread mobilization. The new concurrent model was utilized over a 30-month period and demonstrated that not only did the new liftboat perform as proposed, use of the new model resulted in a 140% more wells and structures being removed over the number expected to have been removed using traditional methods. The actual spend to execute the total work scope was reduced by one-third (33%) and, most importantly, the excellent safety performance achieved by the single, consistent team of specialty workers was recognized with the presentation of the 2013 Safety-in-Seas Award by the National Ocean Industries Association (NOIA).