Volume 34: CCUS Technologies for the Carbon Neutrality: Part II

Construction of a novel superhydrophobic coating surface for downhole tubulars and its protection for CO2 corrosion during CCUS application Qiang Li, Ye-Fei Wang, Mi-Fa Chen, Chu-Han Zhang, Wu-Hua Chen

Abstract

Injected acidic gas of CO2 and produced acidic fluid under high temperature and high pressure are the main factors that cause corrosion of downhole tubular column in Carbon capture, utilization and storage (CCUS) application. The traditional methods, such as corrosion inhibitor mixing and regular injection are not effective method to prevent corrosion of tubular column. In this paper, as a main component, novel organic polysiliconazane polymer (OPSZ) was added to the coating formulation to form a ceramic-like layer with Si-N-Si and Si-O-Si structures on the steel surface. After coating, the non-polar surface energy of the steel decreased to 14.7 mJ/m2. The hardness, thickness, friction strength, corrosion resistance and other related properties of the coating layer were evaluated in laboratory, showing its good tolerance to high temperature in corrosion resistance in the long term, which provided effective protection against corrosion and aging in the application. The novel coating material can be coated on the surface of the downhole tubular column and forming a super hydrophobic surface, which can effectively prevent the contact of acid corrosion medium and metal surface by greatly reducing surface energy, and greatly improving protection efficiency of steel due to carbon dioxide corrosion, indicating good potential in CCUS application.

Keywords CCUS, carbon dioxide corrosion, super hydrophobic coating, low surface energy