Deep drilling in a virtual environment
However, the research work aimed at improving the geothermal process continues – using computers. Researchers from several Swiss universities want to understand with simulations which processes are at play underground when the water is pressed into the hot rock.
In order to test this hydraulic stimulation of the rock permeability, a computer model was developed at the University of Applied Sciences and Arts of Southern Switzerland (SUPSI). It describes the behaviour of fine cracks with rough surfaces and calculates how the high water pressure causes displacements along the fracture surfaces during the hydraulic stimulation.
In addition to the pressure, temperature also plays an important role as shown by researchers from the University of Neuchâtel. The penetrating cold water cools the rock and creates tension. This can lead to further fractures and thus increase permeability.
Using a further model, the researchers studied how the small-scale movements in the rock impact the flow of the water and the extraction of heat as well as the earthquake activity. In this test, this simplified but more comprehensive tool was able to very faithfully reproduce a natural earthquake sequence in Nevada.
A model developed at ETH Zurich also simulates natural processes that occur underground. The researchers used the model to calculate the rise of hot water from deep rock fissures. In doing so, they discovered characteristic temperature patterns that can already be demonstrated at lower depths. In future, this new knowledge could make it easier to detect enormous sources of geothermal energy.