Raw material mobilization from reservoir rock matrix under simulated geothermal conditions

requires an increasing demand in critical raw materials (CRM). However, deposits of CRM
are limited in Europe, generating the need to resort to third countries to meet the demand. To
reduce dependence on importing components, various solutions have been proposed, such
as the extraction of elements from geothermal brines (Hoffman et al., 2018) that represents
an accessible and minimal invasive technique for the environment. For this technique to
function properly and achieve productivity, several factors are necessary. The primary is the
achievable flow rate (Goldberg et al., 2023), also features must be known, like the
characterization of the reservoir rock, brine composition, method of extraction, leaching rates
of the elements, among others. Leaching experiments are a first step to evaluate the
recharging capability of an aquifer through water-rock interaction and generates data about
the leaching elements in quantity.
For this study, with the objective to evaluate the recharge capacity of a geothermal brine and
elements present in it, reservoir analogue samples from the Buntsandstein Formation (one
host rock formation from geothermal reservoir in the Upper Rhine Graben, Germany) will be
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tested in batch autoclaves with different water compositions (synthetic brine, deionized water
and their variations with CO2) to perform water-rock interactions under simulated geothermal
reservoir conditions (200°C) for a period of 58 days. The resulting fluids will be measured by
ICP-MS and ICP-OES to determine the elements occurrence after the experiment, then, their
leaching rates will be evaluated and implemented in a TH(M)C model. This will provide a
general idea of which elements could be extracted sustainably from this reservoir rock in the
URG, but also allow for predicting regeneration times and productivity of extracting elements
from the geothermal brine.