PEEK in Harsh Oil and Gas Environments: Applications and Chemical Aging Response

The oil and gas (O&G) industry is increasingly adopting non-metallic materials for pipelines and downhole components to mitigate corrosion, reduce maintenance costs, and improve performance in harsh service environments. Among high-performance polymers, polyether-ether-ketone (PEEK) has attracted significant attention owing to its excellent mechanical properties, thermal stability, and chemical resistance, making it a promising candidate for aggressive downhole applications. However, exposure to acids, hydrocarbons, water, CO₂, and supercritical CO₂ under high-pressure/high-temperature conditions can alter its microstructure and mechanical performance, necessitating a comprehensive understanding of its long-term behavior. This review summarizes the microstructure, properties, and current applications of PEEK in the O&G industry, including its emerging use in additive manufacturing. It further examines the fundamental mechanisms of gas and liquid diffusion, aging processes (physical, chemical, and thermal), and their effects on the morphology, thermal behavior, and mechanical properties of PEEK. By consolidating findings from studies conducted under representative O&G environments, this review identifies current knowledge gaps and future research priorities, providing guidance for the selection, qualification, and design of PEEK components for demanding oil and gas applications.