<p>Most metallic materials used in oil and gas fields are exposed to complex corrosive environments, where the corrosion behavior is governed not by the simple additive effects of individual media but by their synergistic or antagonistic interactions. These multi-media interactions—such as CO₂–Cl⁻, CO₂–H₂S, and CO₂–O₂–SO₂ combinations—can significantly accelerate localized corrosion, destabilize passive film, or alter interfacial electrochemical reactions, leading to severe material degradation and equipment failure. The dominant interaction mechanisms between typical corrosive species are systematically categorized, threshold concentrations that trigger corrosion mode transitions are identified, and their impact on passive film formation and breakdown is highlighted. Particular emphasis is placed on the evolution of corrosion product layers under combined environmental factors and their implications for long-term integrity of carbon steel pipelines. The findings aim to provide practical guidance for understanding emerging failure phenomena, optimizing corrosion monitoring strategies, and selecting targeted mitigation measures in complex oil and gas production environments.</p>