In March, important part within WP4 of the TKI Geo4All innovation project was successfully carried out: extensive logging, and measurement of temperature and voltage in a new geothermal well at operator EnNatural Geothermal, with consortium partners involved TNO, EBN, TU Delft and Geothermie Nederland.This well is special for the measurements because it was drilled right next to another well in which cold water was injected into the geothermal reservoir for 10 years.
The new well can therefore be used to see exactly where in the subsurface the resulting cooling takes place, and what the effect of the cooling on the subsurface is – the main question in WP4. This data is important for the optimal and safe production of geothermal heat.
The measurements were carried out by SLB and started with two logging campaigns of the geothermal reservoir, the Slochteren sandstone, at a depth of 2.3 km. The log results are in themselves a unique and valuable dataset for geothermal because wells are not usually logged so extensively. But in addition, the logs were also used to determine the precise position of subsequent stress measurements. Tension (the forces in the subsurface) is an essential input for geomechanical models of the subsurface, for example for SDRA Geothermal. To our knowledge, the stress measurements have not been carried out before in a cooled geothermal reservoir as we have in the Netherlands – a unique aspect of this project which helps validate model assumptions and reduce uncertainty in models. The measurement campaign was quick, skillful and successful, and contains a wealth of valuable, as well as surprising and exciting information! So keep an eye out for future presentations and publications.
