Abstract: Ultra-deep extra-heavy oil reservoirs are characterized by poor thermal oil recovery and low waterflood efficiency, of which the efficient economic development can only be achieved by technological innovation. Therefore, a study of physical and molecular simulation was conducted on the development mechanism of viscosity-reducing foam system, and the field practice was carried out in ultra-deep extra-heavy oil reservoir, Lukeqin oilfield. The research results show that the preferred benzene sulfonate anion active agent (HY-3J) can form not only a relatively stable foam system, but also oil in water emulsion to reduce the viscosity of heavy oil in high salinity formation water. The results of foam microscopic seepage experiment indicate that foam can exert a microscopic force on heavy oil by virtue of the viscoelasticity of liquid films, and this force can be used for efficient emulsion and viscosity reduction of heavy oil. The core displacement experiment suggests that the waterflood recovery rate of ultra-deep heavy oil is only 12.7%. However, the viscosity-reducing foam system can significantly reduce water cut and improve oil production rate, in which case the viscosity-reducing foam flooding recovery can be improved by 17.4%. The molecular simulation results turn out that a π-π interaction occurs between the benzene ring structure of benzene sulfonate anion active agent and the aromatic ring on asphaltene, which enhances the van der Waals interaction energy between active agent and asphaltene, thus helping to depolymerize the net structure formed by heavy oil asphaltene and reduce the viscosity of heavy oil. In Lukeqin oilfield, eight well-time viscosity-reducing foam huff and puff experiments have been implemented, and all achieved obvious water precipitation reduction and oil increase, indicating that the viscosity-reducing foam system can effectively improve the development effect of ultra-deep extra-heavy oil.

Key words: heavy oil reservoir, foam, molecular simulation, ultra-deep layer, emulsion viscosity reduction

摘要： 超深层特稠油油藏热采效益差、水驱效率低，需要依靠技术创新才能实现经济高效开发。通过开展降黏型泡沫体系开发机理物理模拟与分子模拟研究，并在鲁克沁油田超深层特稠油油藏进行了矿场实践。研究结果表明，优选的苯磺酸盐型阴离子活性剂HY-3J在高矿化度地层水环境下，既能形成较为稳定的泡沫体系，又能形成水包油乳状液降低稠油黏度。泡沫微观渗流实验结果表明，泡沫可以利用其液膜的黏弹性对稠油产生微观作用力，该作用力可以高效乳化降黏稠油。岩心驱替实验表明，超深层稠油水驱采出程度仅为12.7%。降黏泡沫体系可以显著降低含水率，提高产油速度，降黏泡沫驱提高采出程度17.4%。分子模拟结果表明，苯磺酸盐阴离子活性剂的苯环结构可以与沥青质上的芳香环形成π—π相互作用，这提高了活性剂与沥青质的范德华相互作用能，从而有利于解聚稠油沥青质形成的网状结构，降低稠油黏度。降黏泡沫体系在鲁克沁油田实施了8个井次降黏泡沫体系吞吐，均取得了较好的降水增油效果，这说明降黏泡沫体系可以有效改善超深层特稠油开发效果。

关键词: 稠油油藏, 泡沫, 分子模拟, 超深层, 乳化降黏