盐离子对软体非均相复合驱油体系微界面吸附效应的影响及作用机制研究

The soft heterogeneous compound flooding technology is a significant technique method to enhance oil recovery in high temperature and high salinity reservoirs. However, the salt ions effect on the micro-interface adsorption of this system should be fully understand before perfect the compound flooding theory. In this research, chemistry tests and molecular simulations are used to study the effect of typical salt ions on microscopic interfacial adsorption properties, oexistence manners and interaction force feature of micro-interface adsorption layer in the systems. Aggregation form, relaxation process and rheological behavior of micro-interface adsorption layer in soft heterogeneous compound flooding system are studied through the chemistry test methods, which illustrate the effect mechanism of typical salt ions on the microscopic properties of micro interface adsorption layer. Also, the effects of typical salt ions on the interaction force feature of micro-interface adsorption layer in this system are investigated by using advanced surface force apparatus (SFA). Based on the results, the effect mechanisms of salt ions on the interaction force of micro-interface adsorption layer can be revealed. Furthermore, molecular simulations are conducted to discuss on the mechanism of typical salt ions on the micro-interface adsorption. Based on molecular dynamics model, the effect of salt ions on the adsorption kinetic process and structure-effect relationship of micro-interface adsorption in this system are elaborated from the aspect of energy. It can provide a better understanding of the effect of salt ions on the micro-interface adsorption behavior. This work will lay a scientific foundation and technical support for consummating compound flooding theory.

软体非均相复合驱油技术是高温高盐油藏进一步提高采收率的重要技术手段，要完善该技术理论必须认清盐离子对软体非均相复合驱油体系微界面吸附效应的作用机制。本研究以典型盐离子为研究对象，借助化学测试手段和分子模拟技术，研究典型盐离子对软体非均相复合驱油体系微界面吸附层微观性质、共存方式和作用力特征的影响机制，揭示其作用机理。通过化学测试手段研究典型盐离子对软体非均相复合驱油体系微界面吸附层聚集形态、界面弛豫过程和流变行为的影响，揭示典型盐离子对其微界面吸附层微观性质的影响机理；借助先进的表面力仪探究复合驱油体系微界面吸附层的相互作用力特征，明确典型盐离子对其微界面吸附层作用力的作用机制；建立分子动力学模型，从能量角度探究典型盐离子对复合驱油体系微界面吸附效应影响的吸附动力学过程及构效关系，明确典型盐离子对其微界面吸附行为的影响机理。为软体非均相复合驱替技术理论的完善提供科学依据和技术支撑。

本课题是高温高盐油藏冻胶分散体软体非均相复合驱油技术推广应用的重要理论基础。本研究以典型钠离子、钙离子和镁离子为研究对象，借助化学测试手段和分子模拟手段，探讨了盐离子对软体非均相复合驱油体系微界面吸附层微观性质、共存方式和作用力特征的影响机制。软体非均相复合驱油体系的表面活性剂在冻胶分散体颗粒微界面的吸附属于典型的Langmuir吸附。盐离子的加入会降低表面活性剂在冻胶分散体微界面的吸附能力，导致表面活性剂在冻胶分散体表面的吸附平衡时间缩短，聚集形态发生转变。表面活性剂、冻胶分散体和盐离子在微界面的行为是多系统的动态吸附过程。低浓度的盐离子对软体非均相复合驱油体系微界面的弛豫过程和流变基本没有影响。盐离子的加入会使得冻胶分散体、软体非均相复合驱油体系与不同润湿性云母表面的斥力作用降低。空间位阻效应在不同实验条件下均存在，该效应增强了软体非均相复合驱油体系的斥力作用。表面活性剂能够吸附在冻胶分散体表面，吸附效应强化了软体非均相复合驱油体系的界面活性，盐离子的加入减弱了表面活性剂在冻胶分散体颗粒表面的吸附，但软体非均相复合驱油体系势能大幅度增加，其中MgCl2体系势能最大，MgCl2和CaCl2体系的总能量远远大于NaCl体系总能量。