Model Compound Study of the Mitigative Effect of Crude Oil on Pipeline Corrosion

Internal corrosion of crude oil pipelines can lead to spills that can be very costly, both financially and environmentally. The corrosion is controlled mostly by mitigation methods, such as through design or by the use of corrosion inhibitors. However, it has been observed that some, but not all, crude oils can have an inhibitive effect on their own. There are different mechanisms for crude oils to mitigate corrosion, such as inhibition through the water phase by inhibitor-like molecules native to the crude oil, wettability alteration from water wet steel surface to oil wet, thereby limiting the access of the water to the surface, or by lowering the interfacial tension between oil and water and facilitating dispersion of water in oil, which reduces the likelihood of corrosion by keeping the water from being in contact with the steel surface. Model compounds representative of the naturally occurring surface-active compounds commonly found in crude oil were tested for their effect on corrosion inhibition, wettability alteration, and interfacial tension. It was found that the structure of the compound rather than the type of head group had the largest effect on its efficiency, especially for corrosion inhibition, while the type of head group had a larger effect on the surface wettability and interfacial tension.