A Review of Wax Deposition in Waxy Crude Oil Pipelines: Recent Advances and Future Perspectives

Waxy crude oil plays a vital role in global energy supply. However, wax deposition in pipelines remains a key challenge that restricts its safe and efficient development, including production and transportation. This paper provides a comprehensive review of research progress on pipeline wax deposition in waxy crude oil. First, the mechanisms of wax deposition are analyzed, with particular attention to the formation mechanisms of the wax-gel layer. Second, the major factors influencing wax deposition, including crude oil properties and operating conditions, are summarized and their effects are discussed. Third, commonly used wax prevention and removal technologies in oilfields are reviewed, their advantages and limitations are compared, and special emphasis is placed on several green and sustainable techniques. Finally, based on these analyses, the limitations of current studies are identified and future research directions are proposed: (1) investigating the emerging and potential mechanisms of wax deposition, the synergistic effects among multiple wax formation processes and multicomponent coupled deposition behaviors; (2) exploring the interactive effects among various influencing factors; (3) developing hybrid wax control strategies that integrate multiple inhibition techniques and advancing natural, eco-friendly, and highly efficient inhibition methods; (4) assessing the potential industrial utilization and recycling pathways of wax deposits; and (5) incorporating artificial intelligence and digital technologies to explore their potential in wax deposition analysis and prediction. This review provides theoretical insights and technical references for the safe and efficient development of waxy crude oil.