Reactive Reservoir Systems – Solution and Precipitation of Salts and the Effects on the Hydraulic and Mechanical Rock Properties (ReSalt)

Project Leaders

  • Emilia Götz, Ute Kolb and Hans-Joachim Kleebe

Description

Deep geothermal energy production involves the extraction of reservoir fluids, which are often highly saline and are reinjected into the reservoir after the energy has been harvested. The change in pressure and temperature leads to a dissolution and precipitation of minerals in the geothermal reservoir (reservoir scaling), which triggers a change in the hydraulic and mechanical rock properties.

In this project, a fundamental understanding of reservoir scaling in fissure-dominated flow systems of sedimentary rocks is developed. The crystallized minerals and dissolution phenomena are investigated and characterized using electron microscopy (ESEM and TEM). Through a chemical-mineralogical description of the processes, new approaches can be created to improve the prediction possibilities for changes in permeability and their prevention through additives, with the overall aim to ensure a longer lifetime of geothermal plants.

Fig. 1: a) ESEM-BSE image of calcite (Cal), aragonite (Arg) and halite (Hl), which precipitated in batch experiments and b) SE image of hairy illite (Ilt), clogging pores and thus contributing to a reduction in permabiliy.
Fig. 1: a) ESEM-BSE image of calcite (Cal), aragonite (Arg) and halite (Hl), which precipitated in batch experiments and b) SE image of hairy illite (Ilt), clogging pores and thus contributing to a reduction in permabiliy.
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