de
Filtration characteristics of BHE backfilling materials
Lead Management Subproject Leader
M.Sc. Yannick Reduth (reduth@solites.de)
Participating Partners
In addition to segregation processes within the backfilling suspension and penetration into the surrounding rock, the quality of the backfilling of borehole heat exchangers is determined by filtration processes at the interface of the backfilling and the subsurface. To investigate and assess these infiltration processes, Solites developed a large-scale test rig in the predecessor project QEWS II to represent a borehole as realistically as possible. The borehole wall is formed using mineral materials that allow water to be released from the suspension. It was found that the composition of the backfilling material changes during and after the backfilling procedure as a result of filtration processes and subsequently inhomogeneities can arise within the backfilling. However, these vary depending on the surrounding formations. The experimental setup is further developed to align even more with reality. The further developments include:
- Backfilling by using the contractor method with real measured pressure curves
- Automation of the test procedure
- Replication of the the transition between a confined aquifer and the overlying impermeable rock
- Investigation of the influence of different water release strengths of the backfilling material above and below the transition area on the formation of faults
- Investigation of 8 combination of material, heat exchanger typ and the pressure condition resulting from the surrounding aquifer
