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Deep Earth Energy CEO Kirsten Marcia tells Energy Intelligence that her company has “cracked the code” for geothermal energy via horizontal drilling, starting with a project slated to generate electricity next year by tapping heat from beneath Canada’s portion of the Bakken formation. It’s an innovation she believes will set the stage for wider deployment of the technology throughout the region and perhaps elsewhere. “Our drilling design is the first application of horizontal drilling for power production. It is quite possible to extend it through the larger Williston Basin,” said Marcia. The Bakken oil formation is part of the Williston Basin, which straddles parts of Canada and the US.
Based in Saskatchewan, Deep is just one among a growing list of players aiming to tap the Earth’s heat to produce renewable electricity. Long a laggard behind wind and solar, geothermal energy’s commercial power potential has for decades been confined to just a very few places, such as in volcanic Iceland, where heat from the interior of the planet can be easily tapped. Now, a slew of companies, including many E&Ps and oil-field service firms, are angling to leverage their geotechnical expertise toward making geothermal power a commercial reality.
Deep operates near the US border, where it has drilled wells that tap the very base of the Williston. Geothermal wells are normally drilled vertically, said Marcia, but this ultimately limits the amount of energy that can be produced. “Fluid capacity is key. Our project requires a great deal of fluid injection and we were limited in how much fluid we could produce out of a vertical well,” Marcia says. This led Deep to seize upon horizontal drilling as a solution, but it took a while to work out a well design and field development plan that ensured that enough fluid could be injected, heated and extracted.
Tinkering and Tests
“We spent years getting it right,” Marcia said. The company spent much of that time tinkering with designs, modeling geothermal systems, and drilling a total of six test wells between 2018 and 2021. Deep finally settled on a “ribcage” layout that combines, just like in modern shale drilling, a well uniting a central horizontal shaft with many daughter wells extending from the central well. The design, Marcia points out, is “standard procedure” in the hydrocarbon industry, which Deep says routinely drills wells with “equivalent depth, lateral length and step-outs in resource plays throughout the Western Canadian Sedimentary Basin.”
Deep’s immediate plans envision drilling 10 horizontal production and eight injection wells drilled to an approximate vertical depth of 3,500 meters (11,840 feet) into the Deadwood formation, the deepest sedimentary unit in the Williston. Each will have laterals extending 3,000 meters-4,000 meters, resulting in a total length of about 7,000 meters. The pairs will in turn be separated by about 750 meters, while each production well will have an electric submersible pump installed downhole. Injected fluid is heated by the Earth to about 120°C (260°F), extracted, and used to produce electricity via Organic Rankine Cycle technology before reinjection.
The company estimates that its first 25 megawatts of developed power, or enough to supply about 25,000 households, will use 10% of Deep’s nearly 40,000 hectare (100,000 acre) lease — the entirety of which could “support the build-out of multiple power facilities greater than 200 MW.” Capital outlay for the initial 25 MW plant will run C$8 million (US$6 million) per megawatt, or C$40 million total, a figure Deep believes will fall as it gains experience building and running its geothermal plants. Construction is slated to begin later this year with two well pairs producing a combined 5 MW of power that has been contracted to the provincial utility, SaskPower, starting next summer. Once on line, the company claims it will be Canada’s “first 100% naturally sourced geothermal power facility.”
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