Transient modelling of water condensation rate for top of line corrosion
Diwu Chen A * , Shane A. Morrissy A and Adam Mackenzie AA Wood, Level 1, 240 St Georges Terrace, Perth WA 6000, Australia.
The APPEA Journal 63 S164-S168 https://doi.org/10.1071/AJ22214
Accepted: 27 March 2023 Published: 11 May 2023
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of APPEA.
Abstract
Top of line corrosion (TOLC) is typically a concern in the first few kilometres of wet gas pipelines where water in the warm gas condenses on the cold pipe walls. With the introduction of a subsea tieback to existing infrastructure, the changing fluid composition and temperature profiles may increase condensation in sections not previously expected to have condensation. Accurate prediction of the water condensation rate (WCR) becomes essential to support reliable corrosion modelling. Transient flow simulation of pipeline operating conditions and detailed heat transfer modelling is required to calculate the WCR. This calculation is complicated because the mass of water condensation is very small compared to the fluid mass in the pipeline, and sensitive to glycol that is often present in the aqueous phase for hydrate management purposes. This paper introduces a method to calculate WCR by using detailed transient modelling of the pipeline operating conditions. The fluid thermal hydraulic behaviour and hydraulic pressure drop in the pipeline are considered in the model. The fluid composition in the pipeline and glycol component in the aqueous phase are calculated by using a PVT software package. A few sensitivity studies will also be presented. The implications of Equation of State (EoS) and transient flow module on WCR calculation will be quantified. The WCR sensitivity results will be analysed based on varying inlet temperatures, glycol concentrations, and pipeline heat transfer coefficients. A WCR calculation method will be recommended for TOLC modelling.
Keywords: corrosion, glycol, heat transfer, OLGA, top of line corrosion, transient modelling, water condensation, wet gas pipeline.
Diwu Chen works for Wood as Lead Flow Assurance Engineer. He has been involved in several major oil and gas projects and has 18+ years of experience in flow assurance and relevant project engineering. He is experienced in dynamic integrated modelling and providing flow assurance support from concept to execution stage. |
Shane A. Morrissy has been an Engineering Consultant at Wood for over 4 years. He has extensive experience in flow assurance roles, supporting both greenfield and brownfields’ upstream developments. Shane completed his PhD in Chemical and Process Engineering at the University of Western Australia in 2018. |
Adam Mackenzie works for Wood as Lead Flow Assurance Engineer. He has around 19 years of experience, predominantly in flow assurance roles, and has extensive experience working on complex and large-scale field development projects. |
References
KBC (2017) Multiflash User Guide for Models and Physical Properties Version 7.0. (KBC Process Technology Ltd)Nyborg R, Dugstad A (2007) Top of line corrosion and water condensation rates in wet gas pipelines. In ‘Proceedings of Corrosion/2007’, Nashville, Tennessee, 1–15 March 2007. Paper No.: 07555. (NACE International: Houston, TX, USA)
Schlumberger (2021) Corrosion Module, OLGA User Manual. (Schlumberger)
