To improve oil displacement efficiency under deep reservoir conditions, foam flooding technology represents a critical strategy through the establishment of a stable, long-lasting foam system. A central challenge in this application is to characterize the evolution dynamics of foam under extreme reservoir conditions such as high temperature and salinity. In this study, a performance evaluation experiment of foams generated by different types of surfactants was carried out by using the Waring-blender method. The foam stability characteristics were analyzed on the basis of foam volume, half-life of the liquid solution, and the foam comprehensive index and other related parameters. Based on the microscopic action mechanism of gas-liquid interface, the change pattern of foam performance with concentration, salinity and the coordinated action of core-shell particles were investigated. Both candidate surfactants exhibited good resistance to temperature and salinity. Among them, one surfactant demonstrated superior overall performance, with the foam comprehensive index reaching its peak at an optimal mass concentration of 0.5%. In high-salinity environments, the synergistic interaction between core-shell particles and surfactant molecules significantly enhances foam stability. In particular, the combination of this surfactant with core-shell particles at a mass fraction of 0.5% resulted in a notably higher foam comprehensive index, suggesting its strong application potential. This study quantitatively analyzes the synergistic stability effects of salinity, core-shell particles and surfactant, and reveals the synergistic stability mechanism of salt ion compression electric double layer and particle interface adsorption, providing important theoretical guidance for the development and application of deep reservoir foam flooding.

Foam has wide applications in oil and gas resource development, environmental engineering, and chemical industries due to its favorable rheological properties and interfacial characteristics. However, foam stability is influenced by a complex interplay of external and intrinsic factors, including surfactant type, gas-to-liquid ratio, temperature, and pressure. The combined effects of these factors can significantly alter foam characteristics, with each influencing the other in ways that can either enhance or destabilize foam. This research investigates these factors in detail, exploring how they interact to impact foam stability and how their optimization can enhance foam performance for various applications. The study delves into the role of interfacial tension in foam stability, highlighting how surfactant properties, gas composition, and liquid characteristics contribute to foam formation and stability. The study also reviews advancements in foam technology, particularly in oil production, CO₂ storage, environmental pollution management, and the creation of novel materials, while examining strategies for boosting foam stability under extreme conditions. Findings indicate that the gas-to-liquid ratio, surfactant type, temperature, and pressure all play key roles in foam stability, and fine-tuning these parameters can lead to significant improvements in foam performance. In harsh environments, maintaining foam stability presents substantial challenges. This research further proposes methods to enhance foam stability. Foam technology demonstrates broad potential in fields like oil recovery and wastewater treatment, where optimized foam stability can improve both reservoir recovery and treatment efficiency. This review summarizes the latest advancements in foam stability research, providing valuable insights for the further development of foam technology.

To meet the growing energy demand and ensure national energy security, improving the recovery rate of developed oil fields and tapping into their remaining oil potential have become important ways to stabilize crude oil production. Given the constraints posed by the intricate nature of reservoir formation conditions and the properties of crude oil, including high viscosity, significant heterogeneity, and low permeability, certain techniques find it challenging to be effectively utilized. In view of this, this article introduces enhance heavy oil recovery by in-situ generated foamy oil, foam flooding in deep fractured vuggy reservoirs, and a new CO₂ responsive fracturing foam fluid, respectively. These results can provide constructive conclusions and suggestions for the study of theories and methods of enhanced oil recovery by gas and foam injection in complex reservoirs.