RFID, open-hole packers advancing well interventions; gaps remain in subsea, batteries
By Katie Mazerov, contributing editor
Exploration drilling may rise and fall with the price of oil, but the clock is not stopping for well intervention. In fact, some believe a cost-conscious market can boost the intervention side of the business, as operators seek cost-effective ways to maximize production from mature fields and push for new technologies that provide value and reliability for complicated wells.
“We actually think the current economic challenges facing the industry have, in some ways, been a blessing for well intervention because there is increased focus on the need to improve and develop technologies that ultimately will lower costs,” said Phil Snider, senior technical consultant for upstream technology at Marathon Oil Corp. “When the price of oil is high, people are sometimes content to do things the way they have always done them.
“Also, in a slower market, we have greater access to service companies and their resources because they are often seeking new opportunities,” he continued. “If you have the wherewithal financially during a down cycle to pursue these initiatives, it’s a very good time to do it.”
Alex Crabtree, senior adviser for well intervention, Hess Corp, believes intervention activity is likely to increase in today’s market. “An operator might not want to make a major capital investment in a new field because, for a much smaller investment, that operator can do more intervention to maximize production on an existing well,” he explained.
“Seventy to 80% of oil and gas production is still coming from mature assets,” Mr Crabtree said. “Intervening in those mature assets and maximizing the return is really just practicing good stewardship.”
While the economy may play a role in how the industry approaches intervention, the underlying issues remain the same, Mr Crabtree believes. “The economy limits funding and tends to affect the supply of things in terms of equipment availability, personnel retention and skill sets among suppliers, but it doesn’t affect the technical and performance issues,” he said.
The industry has a “large stock of brownfield wells that have been producing for awhile, and then at the other end of the spectrum, you have these very expensive, complicated wells,” Mr Crabtree said. “Even though the wells are quite different in nature, in terms of intervention, they are actually driving the same issues. You have got to have very cost-effective, reliable intervention techniques that will produce the desired outcome.”
Mr Crabtree noted that while what he calls “blue-sky thinking” is not flourishing at the level it was when capital was easier to come by, technologies are being developed on a number of fronts, including how fiber optics can use be used better, communications systems, tractors, and radio frequency identification (RFID) tag technology to activate downhole systems or gather information.
“In wells where we are doing multi-zone fracturing and so forth, there is continuing innovation on how we can fracture more zones with equipment that is less limiting,” Mr Crabtree said.
By some definitions, well intervention is considered a component of the completion of a well, and an activity that the industry is striving to minimize through technological advances. “We want to develop tools that will keep us from working on or making multiple trips into a well,” Mr Snider explained.
Marathon and its partners have spent five years developing RFID technology and offshoots to improve well intervention, or be able to do more operations without well intervention. “We are going more and more to totally intervention-less completions, where we can remotely actuate more tools in the well rather than having to make repeated trips into the well,” Mr Snider said.
With RFID microchips, operators essentially can “bolt brains onto an existing tool and thus create a brand-new tool,” he continued. “We can use these computer chips to talk to any tool we want. The chips talk to that tool and tell it to do one of 100 tasks we need.”
The industry is also making headway in testing the high-caliber electronics being used downhole, which could lead to more reliable interventions, Mr Snider said. “If we put the tools inside the right kind of packaging, they have a lot better chance of surviving the shock and vibration from drilling.”
Improvements are also being seen in open-hole packer systems, a significant issue for future wells in the Gulf of Mexico. “The way people complete most wells today is by running casing, cementing it in place and then perforating the pipe to get production back into the pipe,” Mr Snider said. “But once you install the casing, you are committing yourself to making many trips into the well to complete the many zones. In some of these deepwater wells, if we can reliably use open-hole packers to provide zonal isolation, we can do many completion operations in one trip,” he said. “For deepwater wells, the casing has to go away.”
Despite the advances, gaps remain. For example, most of the electronic tools available are limited to 300°F, Mr Crabtree noted. “Battery technology is also limited because a lot of the tools that are being developed are using batteries for their power source. So the underlying technology developments need to happen at a greater pace in order to take forward all the other tools that are leveraged off that.”
Mr Snider agrees that lithium battery technology needs significant improvement. “The tools can be fancy, but if the batteries break, you are dead in the water,” he said, explaining that a battery with a 3% failure rate is risky because when several batteries are put together, that’s a 15% failure of downhole tools.
“For critical wells, we’re doing much more battery qualification testing,” he said. “Also, for well intervention, we’re considering using parallel batteries, or power supplies, so if one battery breaks, we have a backup.”
Technology gaps are most evident in the subsea arena, characterized by high temperatures and pressures, where equipment across the board is not rated higher than 25,000 psi. “The whole host of equipment needs to work and function properly at much higher pressures than we’ve ever seen,” Mr Snider said. “To recover reserves in wells in 10,000 feet of water, we’re going to need to utilize electric submersible pumps or other means in order to provide artificial lift at the sea floor or even close to the sand face.”
Another challenge involves fluid loss control valves and barrier valves. “The valves on the market now have a poor track record in conventional wells, and as operators move more toward ultra-deepwater wells with ultra-high pressures, the reliability of these valves is dismal,” Mr Snider said. “The industry has lost millions of dollars because of the failure of these tools, most of which are based on a nitrogen charge system. A lot of effort is being made to radically redesign these valves such that they will be non-nitrogen charged.”
In some ways, the challenges lie not in the tools themselves, but in trying to integrate the various types of intervention technologies. “There is a bit of a disconnect in that there is not really an holistic approach happening,” Mr Crabtree explained. “People are designing completions, designing intervention tools and methodologies of conveying those intervention tools, while other people are developing downhole data acquisition and transmission systems. But to some extent, they are not becoming fully integrated.
“It’s like having a toolbox,” he continued. “You can choose the right tool for the right job, but we need to be smarter about how we put those tools together.”