Temperature Effects on the Anisotropic Electrical Properties of Artificial Sandstones With Aligned Penny‐Shaped Cracks

Abstract Electrical survey methods are widely used to detect and characterize geothermal energy that plays an important role in supporting the sustainable development of our society. Since geothermal systems are typically associated with high temperature, understanding the temperature effects on the electrical properties of fluid‐saturated rocks is essential for the quantitative interpretation of electrical survey data. However, even though cracks are commonly developed in geothermal reservoirs, the effects of temperature on the anisotropic electrical properties of rocks with cracks remain poorly understood. To obtain such knowledge, we prepared artificial sandstone samples with and without aligned penny‐shaped cracks and experimentally measured their electrical conductivity as a function of temperature. We then interpreted the experimental results in terms of the temperature‐dependent variation in the rock porosity, brine conductivity and crack deformation. We also theoretically modeled the temperature induced deformation of the cracks on the anisotropic electrical properties of the artificial sandstones with cracks. The results showed that the cracks dilate with increasing temperature, and the dilation has a significant impact on the anisotropic electrical conductivity of the cracked samples. Theoretical modeling suggested that the increase in the crack porosity due to the temperature induced dilation of the cracks plays a more pronounced role than the crack aspect ratio in affecting the temperature‐dependent anisotropic electrical conductivity of the cracked samples. The results provide a theoretical support for the quantitative interpretation of electrical survey data for the detection and characterization of cracked geothermal reservoirs.