Flow of Hydrothermal Solution in the Crust and Mechanism of Rock Alteration

研制了干热岩石多裂隙水-岩相互作用模拟软件。提出了用具有温度梯度的流动式高压灭菌器来预测干热岩石裂隙变形取热寿命的可能性。此外，还研究了岩粉在静态和流动条件下的岩化情况。在静态条件下，粉末在机械压缩下容易发生石化。通过对Hishikari金矿天然裂隙的观察和矿物沉积年代学的计算，证实裂隙的分布符合分形理论，天然矿脉是由矿物的间歇性沉积作用形成的。通过水-岩相互作用，预测在干热岩石中人工产生的裂隙呈管状。提出了一种通过堵塞管状裂纹来产生新裂纹的新方法，以控制热提取。在水热条件下，锂镁硅酸盐泥浆通过裂隙，导致裂隙中蒙脱石族粘土矿物的固化。研制了一种用于测量水热条件下穿过裂缝的溶液的pH值的传感器。通过与理论热力学计算结果的比较，证实了该传感器测量pH值的准确性。从电化学角度对溶解-沉积过程进行了讨论，证实了金属氧化物与氢氧化物反应生成的络合物导致沉积，沉积对岩石基质的力学性能有很大影响。本研究结果给出了控制热干岩石中多裂纹的方法，为实际抽热发电提供了依据。本研究所设计的设备可用于地球化学、环境科学、材料科学等多个领域的研究。

The simulator of water-rock interaction among multi-cracks in hot-dry rock has been developed. The possibility to predict the lifetime of heat extraction from hot-dry rock due to deformation of cracks was proposed by using flow type autoclave with temperature gradient. Besides, lithification of rock powders was investigated under static and flow conditions. Lithification easily occurred under static conditions with mechanical compression of the powders. It was confirmed by observation of the natural fractures in Hishikari-gold mine and the chronological calculation of deposited minerals that the distribution of the fractures agreed with fractal theory and the natural veins were formed by intermittent repeat of mineral deposition. Cracks artificially produced in hot-dry rock for heat extraction are predicted to be tubular in shape by water-rock interaction. A new method to produce fresh cracks for controlling heat extraction was developed by blocking the tubular cracks. Passing slurry consisting of lithium magnesium silicate through the cracks under hydrothermal conditions, resulted in solidification of smectite group clay minerals in the cracks. A sensor was developed to measure pH of solutions passing through cracks under hydrothermal conditions. The accuracy of pH measured by the sensor was confirmed by comparison with theoretical thermodynamic calculation. Discussion on dissolution-deposition process from electrochemical aspect confirmed that complex formation by reaction of metal oxides and hydroxides caused deposition and the deposit had a large effect on mechanical properties of the rock matrix.The results obtained by this research gave the method to control the multi-cracks in hot-dry rocks for practical heat extraction of generate. The facilities designed in this research are useful for many area of researches such as geochemistry, environmental science, and materials science.