The effect of temperature on the rock fracture permeability is a very important factor in the prediction of the permeability of enhanced geothermal systems and in reservoir engineering. In this study, the flow-through experiments were conducted on a single limestone fracture at different temperatures of 25°C, 40° C and 60° C, and with differential pressures of 0.3 MPa and 0.4 MPa. The experimental results suggest a complex temporal evolution of the fracture aperture. The aperture increases considerably with increasing temperature and reduces gradually to a steady value at a stable temperature. The results of three short-term experiments (QT-1, QT-2, QT-3) indicate an exponential relationship between the permeability and the temperature change ratio (ΔT/T), which provides a further evidence that the rising temperature increases the aperture. It is shown that the changing temperature has its influence on two possible accounts: the chemical dissolution and the pressure dissolution. These two processes have opposite impacts on the fracture permeability. The chemical dissolution increases the permeability with a rising temperature while the pressure dissolution reduces the permeability with a stable temperature. These make a very complex picture of the permeability evolution. Our results show that the fracture permeability reduces 39.2% when the temperature increases by 15°C (during the 25°C–40°C interval) and 42.6% when the temperature increases by 20°C (during the 40°C–60°C interval). It can be concluded that the permeability decreases to a greater extent for larger increases in temperature.

中文翻译：

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在热，水文，机械和化学条件下石灰岩裂缝渗透率的演化

温度对岩石裂缝渗透率的影响是增强地热系统渗透率预测和储层工程中非常重要的因素。在这项研究中，在25°C，40°C和60°C的不同温度下，在0.3 MPa和0.4 MPa的压差下，对单个石灰岩裂缝进行了流过实验。实验结果表明，裂缝孔径的时间变化复杂。孔随着温度升高而显着增加，并在稳定温度下逐渐减小至稳定值。三个短期实验（QT-1，QT-2，QT-3）的结果表明，渗透率与温度变化率（ΔT / T）之间呈指数关系。），这提供了进一步的证据，表明温度升高会增大孔径。结果表明，温度变化对两种可能的影响有影响：化学溶解和压力溶解。这两个过程对裂缝渗透率有相反的影响。随着温度的升高，化学溶解会增加渗透率，而在温度稳定时，压力溶解会降低渗透率。这些使渗透率演变非常复杂。我们的结果表明，温度每升高15°C（在25°C–40°C期间），裂缝的渗透率降低39.2％；温度每升高20°C（在40°C–60°C期间），裂缝的渗透率降低42.6％。 C间隔）。可以得出结论，对于较大的温度升高，渗透率降低的程度更大。