Calcium transport was estimated in the Hijiori Hot Dry Rock geothermal system. During circulation test, we collected scale samples: calcite and aragonite at the pipeline and anhydrite at the deep production well. After a 3-month circulation test, we measured the thickness of calcite scale on the pipeline of HDR-2. The～50 mm thickness means that about 2.7 tonnes of calcite (1.04 tonnes calcium) precipitated. Also we estimated anhydrite dissolution volume from the fluid chemistry at the injection and production wells. Anhydrite dissolved near the injection well by cool water but then Ca re-precipitated as anhydrite in the reservoir with temperature increase. After anhydrite precipitation, calcite precipitated in the surface pipeline and in the shallow well. After 3 months, 7.5 tonnes Ca was contained in the circulation fluid, and 2.7 tonnes Ca was contained in calcite scale in the surface pipeline and shallow production well.
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机译：在Hijiori Hot Dry Rock地热系统中估计了钙的运输。在循环测试期间，我们收集了水垢样品：管道中的方解石和文石以及深层生产井的硬石膏。经过3个月的循环测试，我们测量了HDR-2管道上方解石垢的厚度。 〜50 mm的厚度意味着沉淀出约2.7吨方解石（1.04吨钙）。我们还根据注入井和生产井中的流体化学性质估算了硬石膏的溶解量。硬石膏在注入井附近被冷水溶解，但随着温度的升高，钙以硬石膏的形式重新沉淀在储层中。硬石膏沉淀后，方解石沉淀在表层管道和浅井中。 3个月后，在地面管道和浅层生产井中，循环流体中包含7.5吨Ca，方解石垢中包含2.7吨Ca。
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