EOR system creates seismic shift in waterflood technology

The oil and gas industry has gotten quite creative in its efforts to enhance oil recovery in its aging fields – waterfloods, surfactant floods, COand nitrogen floods, steam floods, and even firefloods have been tried to squeeze more oil out of the reservoir.

But liquids in a reservoir are somewhat lazy, taking the path of least resistance when injected. They will follow the areas of highest permeability, and if a producer is converted into an injector, those areas will be the same pathways that the oil has been using to find the well bore for the past several years. The oil that remains is not likely to be swept through those existing pathways.

"Downhole, the water exits the tubing, finds the perforations, and then enters the reservoir," said Brett David-son, founder, president, and CEO of Wavefront Technology Solutions. "Once it enters into the reservoir, it doesn't go in as a discrete front; it goes in as fingers.

"Waterflooding was first patented in the late 1800s, and though it's added a lot of extra barrels to oil fields, the inefficiency of it is that it can't contact all of the oil in place."

What is needed is a system that can temporarily open additional pathways to help the water sweep more oil. Davidson said his company has that solution.

The earthquake theory

The Powerwave valve is easily installed in an injection well, helping fluids find additional pathways to bypassed oil. (Images courtesy of Wavefront)

Wavefront was founded by Davidson and two professors who were studying the phenomenon of EOR after earthquakes. Dr. Tim Spanos was a theoretical physicist at the University of Alberta, and he was intrigued by the fact that a swarm of earthquakes in a tectonically active area create a temporary increase in oil recoveries.

"There was a lot of research going on at the time using large shockwaves to try to influence fluid flow," Davidson said. "Tim studied that phenomenon and thought that the type of waveforms they were trying to induce weren't really the link to the EOR."

Spanos theorized instead that the type of wave energy that was interacting in the subsurface was more like a tsunami, where the wave moved slowly rather than quickly like a seismic wave.

Spanos approached Davidson and Dr. Maurice Dusseault, a professor at the University of Waterloo, and asked them to study his theory. The resulting process and tool was originally field-tested in Alberta. "We found that by using our downhole technology, we could increase oil recovery during flooding processes," Davidson said. "The problem was that the price of oil was so horrible in 1999 that nobody was really interested in EOR."

The equipment required also was not conducive to a global product launch, so the next few years were spent developing downhole tools that could be shipped to the client by courier.

Ultimately Wavefront purchased part of an oil field in Oklahoma to test the new tools. It got its first commercial pilot contract in 2007. Currently the company has clients in Canada, the US, Argentina, Colombia, and Oman.

How it works

Davidson compared the concept behind the technology, Powerwave, to a kink in a garden hose. Water pressure does not build up behind the kink, but energy does. When the kink is undone, a sudden burst of water spurts out.

Once installed downhole, Powerwave valves can be turned on and off, creating an influx of fluid into the reservoir to cause additional fingering.

"If I take that simple concept and put a valve at the bottom of the injection string, the tubing above the valve is storing energy when it's closed," Davidson said. "When it's opened, all of that momentum is released, and the response of the reservoir is, 'Holy heck!'"

The reservoir responds to the sudden influx of pressure by dilating its pore structure to accept the onrush of the additional fluid. "We don't eliminate fingering," he said. "We create thousands of additional fingers."

Unlike hydraulic fracturing, which permanently creates new fissures in the rock, this is a temporary flexing, but it allows the water to find pockets of oil that have not yet been produced.

Davidson said the technology also can be used for ground water remediation, but for now he is focusing on the EOR business because of the value proposition.

"If I do enhanced recovery, I might get 40% of the oil," he said. "The heavy oil fields in Canada are getting 20% to 25%. Based on what we've seen in the field over the years that we've had tools installed, it may be possible to add another 10% or more to that recovery. "The upside to our clients is their balance sheet. If I can take probable reserves and move them to proven reserves, because I've slowed the production decline and extended the field life, it has a large impact on my client's balance sheet." For instance, the original client in Alberta has slowed its decline rate from 3.4% per month to 1%. Davidson added that in addition to producing more oil, the system also decreases the water cut. Currently the system can manage any type of liquid flooding, including steam. It even injected a mixture of iron filings and corn oil at a NASA project at Cape Canaveral. "It's an emulsion," he said. "It doesn't matter what the fluid medium is. The fluid is always trying to follow the path of least resistance. Wavefront is improving that." He added that the combination that has worked best to date is a combination of Power-wave and a surfactant. So what about fracturing? "A lot of companies have asked us if we can do that," Davidson said. "The quick answer is 'yes, Wavefront can fracture' – if we decide that Powerwave can be used in that application." The primary difference is that typical fracturing processes create a deeply penetrating fracture that forms "lenses" in different directions. Using a pulse-frac method like Powerwave would create less penetration depth but also would create many more fractures.

For now the company is content to help operators wring more from their fields. "Ultimately, every oil company wants to get the maximum amount of oil out of a reservoir," he said. "Powerwave is allowing them to do this without having to drill as many new wells. If they can drill fewer wells and get more oil out, that's a win-win situation."