Experimental Study on Mineral Dissolution Mechanisms and Dynamic Variation Characteristics in Long-Core Reservoirs during Ternary Composite Flooding

This study investigates mineral dissolution mechanisms and dynamic evolution in long-core reservoirs under alkali-surfactant-polymer (ASP) flooding through laboratory-scale physical simulations. Experimental conditions (10.5 MPa,45 °C) replicated reservoir environments using field-derived ASP fluid in a 64-day cyclic displacement test. Quantitative analysis revealed accelerated mineral dissolution over deposition, evidenced by hydroxyl reduction (40% residual) and carbonate accumulation (180.67% increase). Scanning electron microscopy and ionic profiling demonstrated dissolution-deposition dual dynamics: sodium remained stable, while potassium increased linearly. Calcium/magnesium concentrations peaked during initial cycles before stabilizing and declining post-cycle 8. Aluminum exhibited phase-dependent variations, and silicon-aluminum interactions promoted silicate scaling. Notably, equilibrium concentrations of Ca2/Mg2+ inversely correlated with ASP concentration and exposure duration. These findings establish predictive models for ASP-induced scaling patterns, proposing parameter optimization strategies to mitigate reservoir damage and enhance oil recovery efficiency during ASP field applications.