Site Operations

Utah FORGE Site Operations

FORGE stands for Frontier Observatory for Research in Geothermal Energy and the multi-year project sponsored by the U.S. Department of Energy is focused on improving technologies that will accelerate renewable energy production from hot crystalline rock at 2-6 miles (3-10 km) depth below the surface. This type of resource is called an Enhanced Geothermal System (EGS), and the Milford site in Utah was selected in 2018 through a competitive process based on favorable geological attributes and minimal risk of environmental or cultural impact. The onsite activities are directed at testing methods that reduce drilling costs, stimulate pre-existing fractures, promote heat-exchange and sustain long term power production.

The Utah FORGE site is located approximately 10 miles (16 km) northeast of Milford in southwest Utah. The site is accessible by paved and graded roads. There are no permanent buildings, but the area is marked by pads, well heads and a power line, and these are situated on alluvial fan deposits on the west side of the Mineral Mountains, approximately 2.5 miles (4 km) from Roosevelt Hot Springs and the Blundell geothermal power plant (38 MW). Other nearby renewable energy projects include a wind farm (306 MW) and a solar project (240 MW) both operated by SunEdison. The site is 15 miles (24 km) west of I15, the main highway between Salt Lake City and Las Vegas, and it can be reached from turnoffs at Beaver or near the intersection of I15 and I70 at Cove Fort.

West-southwest facing view of the Utah FORGE site in late 2020, showing drill pads, wells, power line supply, and site access.

West-southwest facing view of the Utah FORGE site in late 2020, showing drill pads, wells, power line supply, and site access. Well 58-32 is the deep pilot well that can be used to deploy downhole instruments during 2021 stimulations; the bottom 200 feet of the hole are open and the rest is lined with 7-inch casing. Well 68-32 is dedicated to seismic monitoring with a permanently installed geophone and accelerometer at depths of 921-925 ft. Well 78-32 is instrumented with a Silixa DAS cable including a Constellation fiber cemented in the annulus of the 5 ½” casing to 3268 ft; downhole instruments can be deployed in the casing. Well 56-32 has been drilled to 9,145 feet depth, and it is lined with 5½” casing to the toe; this well is also available for deployment of downhole instruments.

The Utah FORGE underground field is made up of deep wells drilled into hot granite, where experiments are being undertaken to establish an EGS reservoir for geothermal power production. The first deep deviated well 16a(78)-32 was completed at the end of 2020 and the second deep deviated well 16b(78)-32 is scheduled for drilling in 2022. A network of additional vertical wells are being used mainly for seismic and environmental monitoring.

North-looking geological block model of Utah FORGE (looking north) showing the two deep deviated wells (the blue one is for injection; the red one is for production), the four vertical wells for environmental monitoring, the EGS reservoir and the subsurface thermal structure.