Volcanology and Materials Sciences
Fluids in geothermal reservoirs are a mix of metal-rich magmatic fluids and external fluids (meteoric water, seawater etc.). These mixed fluids react with the reservoir host rock and evolve chemically with changes in temperature and pressure as they circulate through the reservoir. Well fluids sampled at Montserrat from exploration wells plot towards the seawater corner of this compositional space. However, fluid inclusions from the drill core rock samples reveal the presence of more metal-rich fluids with a higher magmatic component. In WP2 we will combine the results of the geophysical techniques with sampling of volcanic gases from the summit area (via MVO access and grounding episodes), ‘soufrières’ around the flanks (hot springs, fumaroles, boiling mud pools, steaming ground, warm ponds; Fig. 2) and further measurements of well fluids and fluid/melt inclusions.
We will analyse volcanic rocks samples for a wide range of trace metals to establish which metals have potential value. We will then perform hydrothermal fluid-rock reaction experiments in the Oxford Experimental Petrology laboratory to assess the extent to which metals of value can be leached from volcanic rocks in the geothermal reservoir. Once we have established the metals endowment and spatial distribution of fluids, we will be able to better understand the raw materials potential. We will use information acquired in this project as well are archive material to construct a hydrogeological model of the Montserrat geothermal system.
Having quantified the metals inventory beneath Montserrat we will evaluate its economic potential. A key first step is to explore the strategies available for metals recovery, including from spent geothermal fluids prior to re-injection, down-hole sequestration using functional materials and chemical stimulation of the reservoir itself to yield higher metal concentrations by dosing the reinjected fluids. A particularly novel opportunity that we will explore from a theoretical standpoint is to design metal-sequestering ‘smart’ materials that are stable at well-bottom conditions, building upon our extensive previous work on mineral uptake of trace metals in industrial and geological settings. Candidate minerals include, but are not limited to, micas with high cation exchange capacity, and zeolites, such as the commercially used ZSM-5.
