The paper addresses the application of the NACE International Standard Practice SP0116-2016 for Multiphase Flow – Internal Corrosion Direct Assessment (MP-ICDA), used in-part for the determination of the internal corrosion rate and root-causes for two-30 inch diameter (762 mm) crude oil pipelines (CR180 and CR181) operating in the State of Kuwait. The two pipeline systems went through operational changes such as the introduction of sour, heavy crude oil from ongoing field development. The fluids in the subject pipelines were previously confirmed to be highly corrosive (as many corrosion coupons) were severely corroded in short-term exposures of 3 – 6 months typically and for which was quantified in conducting the Indirect Inspection (IDi) or Step 2 of the MP-ICDA protocol. After confirming the presence of significant internal corrosion defects from an ILI, a dynamic pitting factor was developed using the predicted water accumulation, solids deposition, and wall loss to better capture the high variability in internal corrosion. Ultimately, the MP-ICDA methodology has correctly provided confirmation of the root-causes and mechanisms actually encountered in the pipeline and to thereby recommend a reliable internal corrosion mitigation strategy. The MP-ICDA protocol was successfully used to forecast four theoretical flow scenarios for operations personnel going forward to lower the internal corrosion susceptibility of the subject pipelines.
The Kuwait Oil Company(1) subject CR180 and CR181 pipelines were commissioned in 2014 for transporting crude oil from Point-A to KADMA and KADMA to the Central Mixing Manifold (CMM) respectively over 38.8 km (24.3 mi) (CR180) and 77.2 km (48 mi) (CR181) for a total of 116 km. The CR181 pipeline is immediately downstream of the CR180 pipeline; hence, the outlet of CR180 is the inlet of CR181. Soon after the 2014 commissioning, additional crude sources with compositional differences were added, starting in December 2015 with the addition of a heavy sour crude blend, then in February 2018 with the introduction of Jurassic light crude before transitioning to a purely Jurassic crude in June 2018.
