油藏条件下CO2乳液稳定性实验

CO₂乳液在驱油过程中能够控制CO₂流度,大幅改善CO₂驱油效果。实验测定了油藏条件下温度、压力、矿化度和表面活性剂类型对CO₂-表面活性剂水溶液体系的界面张力、界面扩张模量及乳液稳定性的影响规律。实验结果表明,随着压力的增高,CO₂-表面活性剂水溶液界面张力先迅速减小,之后逐渐稳定,扩张模量先增大,之后逐渐稳定;随着温度的增加,界面张力增加,扩张模量降低;随着矿化度的增加,界面张力先减小后增加,扩张模量先增大后减小。对于阴离子型表面活性剂AOT和OS,随着压力的升高,乳液稳定性增加,界面性能和乳液稳定性具有对应关系;对于非离子型表面活性剂C₁₂E₉P₃,随着压力的升高,乳液稳定性降低,界面性能与乳液稳定性没有对应关系。通过对比AOT、OS和C₁₂E₉P₃,AOT形成的CO₂乳液稳定性能最佳,C₁₂E₉P₃形成的CO₂乳液稳定性能最差,并且对压力较为敏感。该研究结果可以为CO₂乳液在油气田开发中的应用提供一定的理论指导。

An experiment on CO2 emulsion stability at reservoir conditions

CO₂ emulsion is able to control the mobility of CO₂ in the flooding process, thus improving its flooding effect significantly. The influence laws of temperature, pressure, salinity and surfactant type under oil reservoir conditions on interfacial tension, interfacial expansion modulus and emulsion stability of the CO₂ surfactant solution system were determined by experiments. The results show that with the increase of pressure, the interfacial tension of CO₂ surfactant solution system first decreases, and then tends to be stable gradually, while the expansion modulus first increases, and then tends to be stable gradually. With temperature rising, interfacial tension increases first, while expansion modulus declines. With the increase of salinity, interfacial tension decreases first and then increases, while expansion modulus shows the opposite situation. For anionic surfactants such as AOT and OS, with the increase of pressure, emulsion stability declines, and interfacial tension has no correspondence to expansion modulus. Through the comparison among AOT, OS and C₁₂E₉P₃, CO₂ emulsion formed by AOT has the optimal stable performance, while that of C₁₂E₉P₃ has the poorest and is sensitive to pressure. The results of this study can provide certain theoretical guidance for the application of CO₂ emulsion in oil and gas field development.