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Aggreko operation in the Eagle Ford shale formation. (Image courtesy of Aggreko)

Engineering unique power solutions in the oilfields

Amidst the current market climate, fluctuating prices and calls for reduced emissions, oil and gas operators and regulators alike are searching for solutions to increase efficiency, reduce costs and minimize waste.

When it comes to operating in isolated regions of the North American oilfields where there is no access to an existing power grid or where fuel shipments to the well site location is too costly, Aggreko fills the void by engineering site specific power generation units that utilize a portion of the gas stream being produced by a well.

Aggreko, a world leader in temporary power supply systems is leading the charge in engineering site specific solutions to not only reduce operating costs, but also to reduce flaring and the impact to local communities.

What sets Aggreko apart from other operations is the company’s ability to engineer solutions on a case by case basis. “We lead with engineering first, and we support it with products that we manufacture and stock. Most other firms lead with a product,” said David Dickert, Aggreko’s head of oil and gas operations for the Americas. “After engineering a solution with a customer, we can mobilize within a couple of days and make it a reality and build it in the middle of nowhere. We work directly with the producers … either by supplying power or by supplying process enhancement.”

“Some of the applications we support are diesel related but most of the systems we support are natural gas. Today our split is about 60 percent natural gas applications and 40 percent diesel applications,” Dickert said. Lately, the company is focusing on the economics of providing temporary power. With today’s challenge of low oil prices, focus has shifted on finding ways to provide more cost effective options to lower the production cost of a barrel of oil.

A common application found in the oilfield is the use of diesel generators to provide power to an operations site. These generators will often be running non-stop 24 hours a day, seven days a week. Aggreko has developed a system that links with the operational system and will power up as production begins and then cycle down when the system stops, reducing fuel consumption as well as emissions.

Dickert said, “If operating in a field of play that’s running on diesel engines, you have to deliver fuel to these sites at least once a day. When we convert an operation to run on gas, it impacts the local communities by taking trucks off the road and reduces the negative impact on local roads and infrastructure.”

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The systems used also measure a required load and cycles along with the load profile and continually measures the need for power. The automated system senses the amount of fuel needed and will either bring another generator online or offline, depending on the power needed. However, the company has begun utilizing the gas being produced by a well as a fuel source for a site’s power generating systems. “If you look at transitioning from a diesel system to a system that’s operating on field gas, its anywhere from a 40 to 50 percent cost savings on the system,” Dickert added.

This gas, referred to as field gas, is generally high in water content, has a high British thermal unit rating and high hydrogen sulfide content. By utilizing an onsite gas conditioning system, the gas can be utilized for temporary power at the well location. By taking a stream of field gas and using it for power generation, the machines are sometimes able to use the gas as it is. By using a gas conditioning skid, the stream is converted into a useable natural gas liquids (NGL) stream.

What isn’t used for the power generation is then given back to the producer which is then able to either blend with a crude stream or as an NGL stream which can then be brought to market. Dickert said that in most cases, when a conditioning skid is utilized on a well site “those natural gas liquids (NGL) will generate enough revenue to pay for the skid and generate a bit of profit on top of that. We’re able to create a new revenue stream and at the same time get more efficient power from the fuel.”

While Aggreko power generation systems are able to utilize a variety of different fuel streams, one challenge encountered from using gas from a producing well are intermittent volumes of gas coming from a well. Sometimes volumes of gas may initially be higher when operations are started, but the next day the gas pressure may drop and the generator doesn’t receive enough fuel to operate.

To remedy this, two fuel streams are used for the generating system, the gas stream coming from the well and liquid propane stored onsite. If pressure from the gas stream drops below the required level, the system automatically switches to using the contingent fuel source. Dickert said, “The switch is seamless, and you’d never even know the fuel switching is taking place. It creates a highly reliable power plant.”

Focus is also being placed on the use of stranded gas, or gas that can’t be taken to market due to, for example, the high cost of conditioning or the high cost of transportation. These gases are often flared, or burned off into the atmosphere. But in locations that have no access to an existing power grid, Aggrekko has the capability to set up a small power generation site which utilizes the stranded gas which would otherwise be flared off and connect the well locations to the plant via electric transmission lines.

Dickert said, “We recently installed one of these power generating stations at an operation up in Canada. In this one area we reduced the flaring by 25 percent. It’s free fuel for the producer but we’re also positively impacting the environment by reducing the amount of emissions.” Over the last five years the company has been interacting with the shale basins throughout north America and Canada. “We were some of the first to bring alternative fuel applications to the shale plays. We’re now beginning to operate throughout all the Americas, including North, Central and South,” Dickert added.

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