Geothermal energy could mean a renewable future for Colorado's oil fields
The grasslands north of Fort Morgan in eastern Colorado are a hive of energy production. Clusters of spinning wind turbines mark the horizon. And, of course, oil and natural gas operations are everywhere. As far as oil fields go, this one is roughly middle-aged. Wells here are still comfortably profitable. But that won’t last forever.
That’s why the Colorado Oil and Gas Conservation Committee is in the process of hashing out rules to determine how much money oil and gas operators will be required to set aside to pay for plugging wells at the end of their useful lives. The rules are meant to prevent orphan wells, which happen when an operator abandons a well and leaves the state on the hook to clean it up.
But emerging advances in renewable technologies could help extend the operating life of aging oil wells and help address Colorado’s orphan well problem.
Selena Derichsweiler is chief executive officer of Transitional Energy, a local renewable energy startup. She and her business partner, Ben Burke, both worked for years in the oil and gas industry. Now, they are more interested in another thing the wells are bringing to the surface: geothermal energy.
“The temperature is the most valuable to me — wherever it's hottest and has the most flow rate,” Derichsweiler said. “That temperature, that's the thermal resort."
Reconsidering a waste stream
According to Maria Richards, geothermal lab coordinator at Southern Methodist University, every oil and gas well doubles by default as a geothermal well.
“They are already mining the geothermal heat with every single one of their wells,” Richards said. “With every barrel of oil or cubic foot of gas that they bring up, they are mining the geothermal resources.”
But the oil and gas industry has never treated that heat as an asset to be tapped. If anything, Richards says they see the heat — in the form of hot water — as a nuisance that has an operating cost attached to it.
“They have to pay to get rid of that water,” Richards explained.
In part, that’s because oil and gas reservoirs are a lot cooler — 150 to 250 degrees Fahrenheit — than traditional geothermal sources, which are typically closer to 600 degrees Fahrenheit, so the geothermal potential hasn’t been obvious.
But recent advances in heat exchange technology now make it possible to generate geothermal energy at much milder temperatures — like those in the oil fields of northeast Colorado. The energy industry is only now catching up.
“It's a mixture of needing the technology to grow and the oil and gas industry had to realize that they have a resource,” Richards said.
According to a recent report from the National Renewable Energy Laboratory in Golden, geothermal is an under-utilized energy source. The amount of energy produced from it in the U.S. lags far behind other sources.
But that same report cites experts who predict a future where geothermal energy production explodes by a factor of 25 in the next 30 years.
According to Colorado School of Mines professor of practice William Fleckenstein, geothermal has many advantages over wind and solar.
“You look at solar, you can see when the sun sets, because then solar goes away,” he said. “Then you see wind, and a lot of times the wind doesn't blow.”
Fleckenstein says geothermal is fundamentally different: “Then you have this this electricity source that isn't determined by when the wind blows or the sun shines. And that's a that's a huge deal."
Fleckenstein calls it a sleeper renewable energy, on a global scale.
“It's probably the true absolutely boundless type of energy source because Earth is pretty big,” he said.
The oil and gas industry is uniquely primed to take advantage of geothermal energy, according to Jennifer Miskimmins, department head of petroleum engineering at the Colorado School of Mines.
“There's a tremendous amount of overlap,” Miskimmins said. “Petroleum engineering is at its very basics fluid flow in porous media. And geothermal is really the same thing — fluid flow in porous media. There's a lot of the same components as far as things like drilling, reservoir management, stimulation and hydraulic fracturing.”
Miskimmins says repurposing an oil well as a geothermal operation could be an efficient and cost-effective way to bring more geothermal production online.
“We've already got wells that are there,” she said. “So you could spend $2 million and maybe get something that's 20% more efficient. But you've already got something that exists. Why not use it?”
Converting oil wells to geothermal
Selena Derichsweiler and Ben Burke of Transitional Energy estimate that up to 65% of wells in Colorado are good candidates for geothermal energy production. This could extend the life of aging wells by decades — and keep them profitable long enough for operators to pay for their own clean up, plugging and abandonment.
“There's a lot of liability for the state in terms of orphan wells,” Derichsweiler said. “It's those orphan wells that should be reviewed for geothermal potential and converted.”
Burke says that on a basic level, geothermal well design isn’t all that different from oil well design. Purpose-built geothermal wells are wider and designed for higher flow rates. But when an oil well is already drilled and available for conversion, “we can work with what's here because that capital has already been spent,” he said.
Burke and Derichsweiler see the process of transitioning oil fields to geothermal fields as one that will be gradual.
“As one fades out, one can fade in,” Burke said.
Transitional Energy, which was founded last year, will start operating at their first site in Nevada, where they hope to prove their concept. They will bring their technology to oil fields closer to home, in Colorado, in the spring.