A large fraction of mature offshore oil fields in WA are characterised by extremely high water cut and poor productivity, making them potential candidates for CO2 foam flooding, which gives rise to sweep volume and displacement efficiency. Nonetheless, insufficient foam strength prevents its widespread application in field scale.
In this extended abstract, a new formula—AOS/AVS/N70K-T—with well-balanced foamability and foam stability is presented, and the bulk phase behaviour and flow performance of CO2 foam enhanced by this formula is evaluated.
The foaming assessment results indicate that the foamability and foam stability of AOS/AVS/N70K-T are 46.7% and 89.6% greater than that of the widely used AOS/HPAM, respectively. The foam flow experiments demonstrate that:
the foam apparent viscosity under transition foam quality increased by 36.5% in high-permeability rock compared to that in low-permeability rock; and,
the mobility reduction factor (MRF) of AOS/AVS/N70K-T foam obtained the optimal value at the intermediate total gas/solution flow rate (with a fixed gas/liquid ratio of 3:1), while its MRF dropped as the gas flow rate increased.It was noted that AOS/AVS/N70K-T foam displayed a pronounced advantage compared to AOS/HPAM foam during displacement experiments under the same test conditions. Finally, oil displacement experiments show overall oil recoveries of AOS/AVS/N70K-T foam flooding are higher than that of AOS/HPAM foam flooding irrespective of the foam injection mode. Accordingly, CO2 foam flooding enhanced by this formula has proved to be an effective and viable approach to maintain the oil production in WA’s mature oil fields.
Hybrid surfactant-nanoparticles assisted CO2 foam flooding for improved foam stability: A review of principles and applications
