Hydrocarbons play a large role in providing reliable and affordable energy to the masses and will arguably do so for decades to come. But the oil and gas industry—its workforce and the continual technological advancements made by the sector—is also poised to contribute to the world’s diversification of energy sources. In addition to advancements in offshore wind technology gleaned from offshore oil and gas operators, geothermal resource exploration intersects industry know-how.
In January, the US Department of Energy (DOE) selected four new projects to receive funding for establishing geothermal energy and heat production from abandoned oil and gas wells. The agency is partnering with existing well owners and operators to use idle or unproductive wells to access otherwise untapped geothermal potential.
With an expected grant of $1.7 million, one project, out of the University of Oklahoma (OU), Norman, Okla., aims to produce heat from an Oklahoma oilfield for use in nearby schools in Tuttle, Okla. With access to four hydrocarbon wells within a mile, the schools could benefit from repurposing oil and gas infrastructure.
“Researchers from around the world are doing simulations, doing calculations to show that this concept may work, but this is the first time somebody is going to go and do it,” said OU Associate Professor Saeed Salehi in a Jan. 24 release.
There are two known principles for gathering and using the Earth’s heat to create energy. Both involve tapping geothermal hotspots deep below the surface that contain water heated by the Earth’s core. In one case, engineers can harness steam to create energy, in the other, hot water is piped up from deep within the Earth. OU’s project, which is expected to take 3 years, will use the latter option.
Four retired Tuttle oil wells—donated by Blue Cedar Energy—with depths of 10,000-11,000 ft, will be modified and watched for a year. A team of researchers from OU’s Mewbourne School of Petroleum and Geological Engineering will measure energy production to see if output aligns with estimates and models made possible, in part, by software donated by Baker Hughes, the release said.
Region, risk, and cost are some of the constraints to deep geothermal drilling at scale in the US, Salehi said, but Oklahoma has the potential to negate them.
“The largest geothermal operations are currently in California and Nevada,” Salehi explained. “In those regions, geothermal wells generally only need to be half the depth as wells in Oklahoma. However, they are drilled through solid rock, making it a longer, riskier, and more expensive process. In Oklahoma, though the wells are deeper, they are drilled through sedimentary basins—softer rocks.”
Aside from Oklahoma’s geologic advantages, consider the state’s oil and gas workforce. “We have decades of experience drilling Oklahoma’s sedimentary basins and can drill an 11,000-ft well in a week. That cannot be done in other places, even at shallower depths,” said Salehi.
Now add repurposed fossil fuel assets. “The largest expense in geothermal energy is drilling the well. We’re eliminating it,” said Salehi. There’s an abundance of retired wells in the state—close to schools, factories, farms—that adds to the appeal.
“In Oklahoma, we do not need to invest in miles of pipelines to deliver energy to end users,” Salehi said.
While the scope of the project does not include the next step of heating the schools with geothermal energy, only ensuring that it is possible, the team hopes when the current project is completed, it can apply for new grants and state matching funds to make heating the schools with geothermal energy a possibility, according to the release.
The university also plans to launch a new geothermal-focused undergraduate degree, GeoEnergy Engineering, this fall.
As the need for reliable and affordable energy continues to grow, researchers around the world are likely to follow such studies with interest.