Characterization of reservoir rock samples under in situ conditions is crucial for evaluating the quantity and exploitable potential of geothermal energy. However, reservoir characterization is impeded by the lack of precise assessments of rock properties at in situ temperatures. To address this, high-temperature micro-computed tomography was deployed, integrating digital volume correlation (DVC) technology to ascertain the strain exhibited by pores and minerals. The findings reveal the neglect of the effects of mineral displacement at high temperatures previously. The strain within the sandstone is heterogeneous and primarily concentrated at the edges of large grains of brittle minerals and the fillings among them. The weak interfaces among diverse large-grain brittle minerals and their fillings cause strain in sandstone. At 105 °C, the average equivalent strain in sandstone was 0.03275 determined by DVC, significantly surpassing the strain of mineral thermal expansion, which remained below 0.001. Most of the strain was caused by mineral displacement, not mineral thermal expansion. The porosity of the sandstone decreased from 5.02 to 4.84% as the temperature increased from 30 to 105 °C, and some of the connected pores were transformed into independent pores at high temperatures. The tortuosity of the sample increased from 3.88 to 3.97 from 30 to 105 °C, respectively, and the temperature increase caused permeability reduction from 67.9 to 58.2 mD (1 mD = 9.869233 × 10⁻¹⁶ m²). The thermal treatment experiments demonstrated that mineral displacement in sandstones is a universal phenomenon at high temperatures and it leads to changes in sandstone pore structure and permeability. This study advances a new path to investigate geothermal reservoir properties at high temperatures and offers novel understanding.

原位条件下储层岩石样品的表征对于评估地热能的数量和可开发潜力至关重要。然而，由于缺乏对原位温度下岩石特性的精确评估，储层表征受到阻碍。为了解决这个问题，部署了高温微型计算机断层扫描，集成数字体积相关（DVC）技术来确定孔隙和矿物所表现出的应变。研究结果揭示了以前忽视了高温下矿物置换的影响。砂岩内的应变是不均匀的，主要集中在大颗粒脆性矿物及其填充物的边缘。各种大颗粒脆性矿物及其填充物之间的弱界面会导致砂岩产生应变。在 105 °C 时，DVC 测定的砂岩平均等效应变为 0.03275，显着超过矿物热膨胀应变，后者保持在 0.001 以下。大多数应变是由矿物位移引起的，而不是矿物热膨胀引起的。随着温度从30℃升高到105℃，砂岩的孔隙率从5.02%下降到4.84%，并且部分连通孔隙在高温下转变为独立孔隙。从30℃到105℃，样品的曲折度分别从3.88增加到3.97，温度升高导致渗透率从67.9mD降低到58.2mD（1mD=9.869233×10 ⁻¹⁶ m ²