A team of OU researchers has joined with researchers from other universities across the country to develop a technology to increase the efficiency of geothermal energy drilling.
According to a press release from OU research, an OU team is aiding in the development of “smart lost circulation materials” intended to help prevent the loss of fluids and energy in the geothermal drilling process thanks to a $1.79 million grant from the U.S. Department of Energy and a $500,000 cost share from “various entities.”
Geothermal energy uses heat naturally generated beneath the Earth’s crust to create power by drilling deep wells into the ground and extracting the heat, usually with water or steam.
“One of the major challenges with geothermal drilling and extraction is … the high temperatures,” said Saeed Salehi, the project principal investigator and a professor of petroleum and geological engineering at OU’s Mewbourne College of Earth and Energy. “We’re talking about temperatures beyond 400 to 500 degrees Fahrenheit and with the type of rocks we see in geothermal drilling – those are usually very hard rocks.”
Salehi said a common problem encountered in geothermal drilling is the loss of fluids necessary to continue drilling through fractures created in the layers of rock.
To mitigate the fluid loss, Salehi said researchers including himself and others at OU – in collaboration with teams from Louisiana State University and Penn State University – are developing a new type of an already-existing technology.
“A lot of materials, they degrade in high temperatures, they don’t work. We are developing some ‘smart-type’ polymers that are triggered by the heat,” Salehi said. “Technically they are called shape-memory polymers, or SMP. They have been used in the polymer industry for decades, not very long, but in terms of geothermal drilling it’s completely new.”
According to Polymers, a peer-reviewed, open-access monthly science journal, shape-memory polymers are a type of material with the ability to expand or change shape from an original form in response to external stimuli or condition change, like temperature. When conditions are normal again, the polymers are able to return to their original form.
“You mix them with your fluid, but they aren’t activated until the temperature triggers them.They start activating and then they start to expand, so basically they … will help us to seal those type of fractures,” Salehi said.
The research project, which Salehi said began in June, will have three phases. Phase one, the current phase of the project, involves developing the material, which must be able to withstand temperatures in excess of 400 degrees. Salehi said other SMPs exist at the moment, but they are designed for much lower temperatures.
Salehi said the material will be applied to fractures for testing in laboratories in phase two. According to the release, phase three will involve computer data collection and simulations to determine the best combinations of materials and drilling methods. The research will be carried out over the course of two years.
The research team hopes to be able to create a product that can be commercialized for widespread and affordable use in the future, Salehi said.
“The potential for geothermal energy is huge. If we are able to commercialize technologies to extract (the energy), we are able to reduce our reliance on oil and gas,” Salehi said, “so states like Oklahoma can use this type of energy for heating, for electricity, so I think it has very big potential for our nation and for states in terms of developing other energy sources.”
Salehi said he expects geothermal energy to see growth in the next decade, based on current trends in Europe.
“In Europe, (geothermal energy) is getting big. … Iceland is getting all its energy sources from geothermal, or (at least) a majority of it. So Germany is going towards that potential,” Salehi said.
Salehi said the adoption of more geothermal energy is slower in the United States than Europe, but the industry is growing steadily.
“I think the government is investing heavily on this. Compared to other places the U.S. geothermal (energy industry) is small, but it’s getting bigger and bigger.”