Temperature and Pressure Effects on CO2 Foam Aging Revealed by Multi-Descriptor Optical Analysis and Complementary High-Pressure Evaluation

Optical methods are widely used to evaluate foam stability, but their signals integrate liquid drainage, phase redistribution, bubble-size evolution, and coalescence, limiting mechanism-specific interpretation. This study applies a measurement-aware, multidescriptor strategy combining bench-scale Turbiscan screening, an independent high-pressure CO2-foam visual-cell campaign, and porous-media core-flood evaluation. At 30, 45, and 60 °C, initial gas entrainment, liquid drainage, apparent optical bubble evolution, foam–liquid boundary migration, regional backscattering variation, and the Turbiscan Stability Index were evaluated. High-pressure CO2-foam performance was independently assessed over 12–22 MPa using maximum foam volume and foam half-life. Increasing temperature enhanced initial gas entrainment but accelerated subsequent structural aging, as indicated by faster drainage, earlier boundary migration, a higher apparent cubic-radius evolution coefficient, and greater cumulative optical variation. The apparent cubic-radius evolution coefficient increased from 1.14 × 105 to 2.27 × 105 μm3·min–1 between 30 and 60 °C. In the high-pressure campaign, increasing target pressure under the adopted density-based charging protocol was associated with higher maximum foam volume and longer half-life, although the adverse effect of elevated temperature remained. Because CO2 inventory, surfactant-stock charge, and ethanol content covaried with target-state CO2 density, this trend is interpreted as a combined pressure–charge/formulation response rather than an isolated thermodynamic pressure effect. At 22 MPa, increasing temperature from 30 to 60 °C reduced the maximum foam volume from approximately 1190 to 865 mL and the half-life from 198 to 125 min. The core-flood experiments provided initial porous-media evidence: CO2/E-1340 foam increased the final oil recovery factor to 53.24%, compared with 40.79% for CO2 flooding and 26.97% for brine flooding. During foam treatment, the differential pressure increased from 0.26 to 2.68 MPa and stabilized at 1.98 MPa after treatment, corresponding to a resistance factor of 10.308 and a residual resistance factor of 7.615. These results extend the bulk-cell and high-pressure screening observations to initial porous-media evidence of increased flow resistance and improved displacement performance under the tested conditions. Broader validation using additional reservoir-fluid systems and multiple core conditions, together with experiments that independently decouple pressure from CO2 inventory, remains necessary before the results can be generalized to formation-specific EOR or CCUS applications.