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Artificial Lift Techbook 2016

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ARTIFICIAL LIFT TECHBOOK: TECHNOLOGY 30 | May 2016 | hartenergy.com Gas lift Gas lift systems face slightly different issues than ESPs and rod pumps since they require a source of gas to lift the hydrocarbons to the surface. But they're widely used in unconventionals. "On the shale plays, because the pressures are pretty low, operators start using gas lift from the beginning," said Sudhir Jain, senior oil and gas con- sultant for Emerson Process Management. "Other- wise that oil will never come up." Gas lift pumps require a different form of opti- mization than ESPs. "The interesting thing about this is that, generally speaking, the more lift gas you use, the more oil you can produce—up to a point," said Lou Heavner, a consultant for systems and project engineering at Emerson. "That point is where the backpressure created on the well by too much lift gas is actually inhibiting the fow of oil up the well. There is a natural optimal point for any given well for producing the maximum amount of oil." Another challenge is the availability of the lift gas itself. "Sometimes if you have a number of wells, you may have a limited supply of gas for the gas lift," Jain said. "That is the time you have to allocate the distribution amongst all of the wells in a way that maximizes total production." This is addressed by optimization, he said. "Every well has a well test curve, which is basically production rate vs. gas lift at different gas-lift rates. That is one of the essential things you need to have. You want to achieve the optimal fow for each well, but sometimes you don't get to the optimal point because you have insuffcient gas." In a single-well situation where gas is plenti- ful, added Heavner, the optimal fow rate is deter- mined by the production curve ftted to well test data. With multiple wells and constrained gas supply, or in some cases by other considerations like water production, it's harder to allocate that gas in an optimal way. "That's the optimization problem that we're most enthusiastic about right now," he said. The solution is offered as either an open-loop or closed-loop system that gives the optimal set points to open or close lift gas valves to vary the lift gas fows for all of the wells using gas lift. "That gives our customers the maximum reve- nue," Jain said. Another advantage that Emerson provides in its systems is the wireless component. "Our abil- ity to make communications among the field devices wireless can rapidly improve the deploy- ment of these types of solutions," said Deanna Johnson, global wireless marketing manager at Emerson. "When the unconventional patch was on a tear, you couldn't find electricians to lay wires or people to dig ditches to put the wires in so that they would be protected. Wireless has made a huge difference in people's ability to cost-effectively and rapidly deploy these types of solutions." The human element Automation is changing the way people view arti- fcial lift systems. The ability to collect data in real time and control equipment remotely is having an enormous impact on productivity in the feld. "One of the things I've seen on platforms is that even if you have highly trained staff, they can't take full advantage of these systems," Jain said. "And you don't have these kinds of experts all over the world. It's not that it can't be done manually. But modern automation is real-time and does all of the calculations by itself." While adding automation effciencies does cost money, the benefts are obvious. "The artifcial lift industry as a whole has historically been late to adopt this technology, but those who did adopt new artificial lift technology and automation processes are now in the majority," Mathiravedu said. "Clients are very receptive to automation and improved technology, which ultimately results in increased production, uptime and runlife. In the modern age of remote operations and high-eff- ciency requirements, smart controllers with real- time optimization and solutions have been adopted and are now heavily relied on." Added Seale, "Just the sheer volume of digital oilfeld projects has increased, and customers have really started seeing the benefts of having a real- time center or a collaborative work environment and the value that it gives from an improved work- fow and the way that people work." n

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