This study investigates the rheology and stability of nanoparticle-stabilized CO₂ foams under reservoir conditions (high temperature and high pressure) for fracturing applications. The effects of different parameters on foam apparent viscosity and foam stability were experimentally investigated including the effects of nanoparticle concentration, salinity, foam quality ($\text{Γ}$), shear rate and temperature. The power law model was applied to calculate foam apparent viscosity owing to its pseudo-plastic behavior, and the changes of foam heights over time were used to evaluate foam stability. Results showed that the CO₂ foam apparent viscosity featured a mountain-shaped curve versus $\text{Γ}$, with the peak apparent viscosity obtained at 70% foam quality. The increase of salinity (up to 11%) in the continuous phase improved both foam stability and rheology. Higher nanoparticle concentration could contribute to better foam stability, but there was a threshold concentration, above which the foam apparent viscosity remained stabilized. The CO₂ foam stabilized by nanoparticles displayed a shear-thickening behavior as the experiment flow rate increased from 6 mL/min to 18 mL/min. Further studies showed that as the total flow rate increased, the CO₂ foam became finer-textured with better stability. Elevated temperatures could undermine foam apparent viscosity and long-term stability. The results of this study could provide guidelines as to the design of foam fracturing systems for field applications.

这项研究调查了在压裂应用中在储层条件（高温和高压）下纳米颗粒稳定的CO ₂泡沫的流变学和稳定性。实验研究了不同参数对泡沫表观粘度和泡沫稳定性的影响，包括纳米颗粒浓度，盐度，泡沫质量的影响（$\text{Γ}$），剪切速率和温度。运用幂律模型计算泡沫表观粘度（由于其假塑性行为），并使用泡沫高度随时间的变化来评估泡沫稳定性。结果表明，CO ₂泡沫的表观粘度相对于$\text{Γ}$，在70％的泡沫质量下获得的峰值表观粘度。连续相中盐度的增加（高达11％）改善了泡沫的稳定性和流变性。较高的纳米颗粒浓度可以有助于更好的泡沫稳定性，但是存在阈值浓度，在该阈值浓度以上，泡沫表观粘度保持稳定。随着实验流速从6 mL / min增加到18 mL / min，被纳米颗粒稳定的CO ₂泡沫表现出剪切增稠行为。进一步的研究表明，随着总流量的增加，CO ₂泡沫质地更细，稳定性更好。高温可能会破坏泡沫的表观粘度和长期稳定性。这项研究的结果可以为现场应用的泡沫压裂系统的设计提供指导。