Vessel, plug selection identified as keys to cost reduction

What lesson can plugging and abandonment take from the latest treatments for coronary heart disease? The answer is that new technology can be inserted into a problem area without affecting other things nearby, according to Debbie McIntosh, head of OTM Consulting’s subsurface and wells practice.

A joint industry project is aiming to assess the economics of using MODUs (crewmember / Creative Commons)

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“There’s the old method, the lengthy method, [the] time-consuming, high-cost, high-risk [method],” McIntosh said at the 8th Annual Decommissioning & Abandonment Summit in Houston.

She continued with a story about the father-in-law of a colleague who went into hospital for what would ordinarily have required bypass surgery but in his case was fixed with a couple of stents. “There’s the new technology that can be inserted with little effect to many of the other things nearby. It’s quicker. It’s cheaper. It’s more effective. It’s not applicable in every situation; but in the ones it is – it saves a lot.”

Stents – small mesh tubes placed in arteries and expanded as part of coronary interventions – were actually patented by a company active in both the oil and gas and medical industries, McIntosh noted. The company developed it as an expandable tubular technology realizing it could be placed down a well just as easily as in an artery. The lesson, she said, is that “there’s opportunity for technology transfer everywhere”.

Plethora of new technologies

Many new and innovative technologies have appeared on the scene since 2009 – the year Marathon Oil, while planning the plugging and abandonment (P&A) of the Brae Complex in the North Sea, bemoaned the lack of such technologies, according to McIntosh.

She highlighted a number of technologies that in her opinion could prove groundbreaking, including two – resins as a replacement for cement; and rigless P&A – that were discussed repeatedly at the conference. The other technologies to watch, in her opinion: bismuth plugs, which provide a metal-to-metal steel across the casing, which with their low corrosivity “could also be a good alternative to cement”; and thermite seals, whose high-energy downhole reaction could potentially negate the requirement to pull tubulars.

The average age of subsea wells is increasing, meaning the industry will need to conduct more intervention and well P&A than ever before (Source: Endeavor Management / Quest Offshore Resources)

The industry has identified fantastic technologies, she said, noting that the next stage is to understand how to use them: “Unless they fit into your plugging-and-abandonment strategy as a whole, then there’s no benefit. There need to be ways to integrate them to ensure that you are getting the cost benefits, and you are getting required assurance.”

To effectively reduce costs, the right technology needs to be selected for each well, McIntosh said. But she warned that a bespoke method for every single well would not result in big savings.

She explained: “You have to look across your portfolio of assets, across the different wells you have, analyze the survey data and any information you have on the wells, and identify what the common trends are: What are your common challenges? What are the things that you need to address by something new? What are your biggest risks and concerns as a company? Are you more concerned with how you are perceived? Are you more concerned with leading the forefront of new technology? Are you more concerned with learning from others and following in their footsteps? These are all factors that must be fed in to your plugging-and-abandonment straegy.”

All about the bottom line

The questions posed by McIntosh are of the sort that need to be addressed by a combination of collaboration and individual effort, she said, pointing out that OTM has been working with operators and technology vendors on these issues. The industry needs and concerns have been well documented, and OTM is now working with its clients to identify solutions, fill technology and knowledge gaps, learn from others and assess the suitability of regulations, explained McIntosh.

Endeavor Management will hope to provide solutions to some of these questions as early as May this year, when it expects to complete a joint-industry project (JIP) on cost reduction. Ten companies are participating in the JIP: ExxonMobil, Shell, Freeport-McMoRan, Marubeni, Stone Energy, Aker Solutions / Baker Hughes Alliance, GE Oil & Gas, Halliburton, Oceaneering, and Petrolatina Assets. The scope of the project will be expanded if other companies join the JIP.

Bruce Crager, Executive Vice President of Endeavor, said the study aims to provide solutions to a number of issues operators are having trouble with. The study results will only be shared with the funding companies although some high-level learnings will be presented at industry conferences, he said.

One goal is to develop an economic model to predict the costs of using three basic vessel types in subsea intervention or P&A: light-well intervention vessel with no riser, which Crager estimates can complete 60-70% of all tasks that might need to be performed; a vessel with a small-bore intervention riser, which can complete an estimated 70-90% of tasks; and a mobile offshore drilling unit (MODU) with full subsea riser system, which can complete all tasks but generally costs more – falling rig rates notwithstanding.

A second task is to determine how to achieve MODU capabilities for subsea well P&A at a lower price than is currently being achieved. A third is to evaluate the total costs of resins as a replacement for cements in well P&A.

Crager provided an overview of the key lessons from from previous work on this topic, including: having predetermined solutions to possible problems which might be encountered; ensuring the host facility remains in place until all the decommissioning work is completed (“you may have to flush the flowlines from the host facility. You may need to do other things, and having a place to do that from can be very valuable during the decommissioning activities”); and he stressed the importance of having an experienced team.

He concluded: “Each P&A is unique. Don’t underestimate the time required to figure it out. We did an internet survey as part of our previous study. We had feedback that about 50% of the subsea decom projects took over a year to plan the project, and most took four to six weeks to do the project.”