For the long-term safe operation of carbon capture and storage (CCS) projects, the leakage of supercritical carbon dioxide (SC-CO₂) along a fault is an important factor that needs to be monitored. To investigate the phase change and fault deformation associated with SC-CO₂ leakage along a fault, this study carried out five groups of SC-CO₂ leakage experiments at different initial CO₂ temperatures. The volume of the CO₂ storage container (100 mL), CO₂ initial pressure (8 MPa) and fault confining pressure (10.5 MPa) were controlled at the same values. The CO₂ phase change and fault internal-external strains response were monitored by high-precision fiber Bragg grating sensors throughout the experiment. The results show that (1) Temperature and strains response times were 1 and 2.5 times longer than pressure, respectively. (2) The viscosity greatly influenced the determination of the critical temperature T₀ = 45 ℃. (3) The fault internal strains were more than twice that of the external one; except for the entrance, the fault internal and external strains states were opposite at the beginning of leakage; all other positions on the fault surface showed compressive strains except for the tensile strains at the entrance. (4) The distribution of the inflection point of temperature-pressure curves may be used as a basis for distinguishing CO₂ leakage from faults (near the triple point) or pipes (far from the triple point). This study provides technical and theoretical support for laboratory-scale studies on the mechanism of internal and external strains differences caused by phase transition of SC-CO₂ leakage along faults.

对于碳捕集与封存（CCS）项目的长期安全运行，超临界二氧化碳（SC-CO ₂）沿断层的泄漏是需要监测的重要因素。为了研究与SC-CO ₂沿断层泄漏相关的相变和断层变形，本研究在不同初始CO ₂温度下进行了五组SC-CO _{2泄漏实验。CO 2}储存容器容积（100 mL）、CO ₂初始压力（8 MPa）和断层围压（10.5 MPa）控制在相同值。CO ₂在整个实验过程中，高精度光纤布拉格光栅传感器监测相变和故障内外应变响应。结果表明 (1) 温度和应变响应时间分别是压力的 1 倍和 2.5 倍。(2)粘度对临界温度T ₀ = 45 ℃的测定影响较大。(3)断层内应变是外应变的2倍以上；除入口外，在渗漏初期，断层内外应变状态相反；除了入口处的拉应变外，断面上的所有其他位置都显示出压应变。(4)温度-压力曲线拐点分布可作为区分CO _2的依据故障（靠近三相点）或管道（远离三相点）的泄漏。_{该研究为SC-CO 2}沿断层泄漏相变引起的内外应变差异机理的实验室规模研究提供了技术和理论支持。