A team of Golder researchers is helping unlock the geothermal puzzle – accessing a clean source of power that far from being geographically constrained, is available just about anywhere on earth. These development have caught the eye of the U.S. Department of Energy (DOE). In 2014, DOE started its Frontier Observatory for Research in Geothermal Energy (FORGE) to develop an underground field laboratory for developing, testing, and accelerating breakthroughs in enhanced geothermal system (EGS) technologies.
The FORGE laboratory, located in southwest Utah and operated by the University of Utah, is intended to enable cutting-edge research and drilling and technology testing, as well as to allow scientists to identify a replicable, commercial pathway to EGS.
The plan at the FORGE site is to drill a pair of wells in the range of 2.2 km (7,300 feet) deep into the granite.
The rock surrounding the wells at the appropriate depth will be subjected to hydraulic fracturing to improve the fluid-carrying ability of the natural fractures. Water will be pumped down one well, designated as the injection well. That water is expected to flow into and through the natural and augmented fractures, picking up heat from the rock mass. At the recovery well, the heated water (expected to be about 200 degrees C) will be pumped out as steam and used to drive a turbine and generate electricity.
Golder’s contribution to FORGE, starting in 2016, has been to use our FracMan® software to analyze data from a test well to develop a model of the fractures in the target rock mass. The test well has yielded data on the natural fractures that exist in the rock mass, and the hydraulic properties of those fractures. The Golder team has also developed models of how the rock mass can be expected to react as a result of hydraulic fracturing.
This is key to developing an energy resource that is long-term. For this dual-well approach to geothermal energy to work sustainably, it will not be sufficient for the water to flow in along a single path of fractures between the two wells – the rock mass along that path will cool down too quickly. Rather, a successful geothermal reservoir will include many small fractures over a wide area, so that the water flows slowly, and through many different pathways, absorbing heat from a large mass of rock.
Initial results from Golder’s work demonstrate that the rock mass chosen for this test site will perform in a way suitable for creating a sustainable reservoir.
Over the five years projected for the FORGE program, Golder will continue to be involved, supporting teams of researchers using a variety of technologies to develop viable, commercially feasible solutions for geothermal energy. The result, it is hoped, will be a clean, widely available source of energy using only heat that is tied to the origins of our planet.