Experimental Study on the Thermal Insulation and Seawater Corrosion Resistance Effects of Silane-Nanoceramic Coatings in Subsea Riser

Abstract In China's Bohai Sea, there is a large amount of heavy and viscous oil needs to be produced. At present, the steam huff and puff is currently the most effective means of producing heavy oil reservoir, and the riser system is a conduit system that connects the subsea wellhead and the rig and also plays an important role in the circulation of steam. Thus, as an important circulation channel in thermal recovery well in offshore heavy oilfield, the riser needs to have heat insulation effect. The silane-nanoceramic composite as a new type of heat insulation coating material has the advantages of low thermal conductivity, high insulation effect and seawater corrosion resistance than other insulation coatings. This paper firstly utilizes infrared heating technology to test the thermal insulation performance of ordinary nanoceramics and silanenanoceramic coatings. Then the actual service condition of thermal insulation coating is simulated by using the test of the riser heating device. The thermal barrier effect of three types of riser thermal barrier coatings is evaluated, the influence of coating structure, and coating thickness on the insulation effect of silane-nanoceramic composite coating are also analyzed. Considering the corrosion resistance of the riser coating system in seawater, this paper also tests the anti-seawater immersion properties of the coating and salt spray corrosion resistance, and uses two field experiments to verify the actual results. The results figure out that silane-nanoceramic ceramic coatings have better thermal insulation properties than ordinary ceramic coatings. The thermal conductivity of silane-nanoceramic can be as low as 0.028 W/m·K, and heat insulation rate can reach more than 70% when the inner temperature is kept at 350°C, so the silane-nanoceramic coatings have obvious advantages compared with other insulating materials. External wall spraying coating has higher insulation effect. With the increase of coating thickness, the insulation effect is more significant. The insulation preservation rate can be more than 80%, when coating thickness reached 500um. The corrosion resistance experimental results show that the coating anticorrosive life rises with the increase of the coating thickness and the field experiments prove the silane-nanoceramic composite coating has good seawater corrosion resistance, salt spray resistance and antifouling performance.