| Title | A Combination of Nano-structured Calcium Silicate Hydrate (CaSil) and Calcium Inhibitor Technologies Eliminates Calcite, Silica, Stibnite and Aluminate Scales |
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| Authors | T. Borrmann, J. H. Johnston, M. Schweig, H. P. Fraser |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The development of high enthalpy geothermal resources is held back by the formation of a variety of mineral scales formed from minerals dissolved in geothermal reservoirs. Calcite scale can occur just before the wellhead, while silica, stibnite and aluminate scales form in heat exchangers, pipes, valves and reinjection wells. Calcite scale inhibitors (CIS) can be injected down well to control calcite scale formation. For other mineral scales, current remediation techniques only act as delay tactics and do not solve the issue. Removal of scales using costly processes necessitate significant plant downtimes. Reinjection wells block up and need to be treated regularly or even abandoned and re-drilled. We have demonstrated on fully automated pilot scale an alternative silica treatment technology, CaSil technology, which eliminates the silica scale problem. The CaSil technology works by transforming silica into calcium silicate hydrate (CaSil), which does not stick to tubes, pipes and heat exchangers. The technology also eliminates stibnite and aluminium related scales due to the resulting pH preventing the formation of the former. The aluminium being trapped along with silica in the CaSil product. Combining the CaSil technology with calcite inhibitors enables more heat and electricity to be extracted from geothermal brine. Direct heat applications become possible that cannot be unlocked otherwise. We present laboratory findings and insights from our fully automated pilot plant work to show the opportunities opened by the two combined technologies. |