Research

RP3.2-04: Deposition of Cohesive Gas Impurities in pipelines carrying coal seam gas

Executive Summary

This project studied the deposition of conductive cohesive gas impurities in pipelines carrying coal seam gas (CSG). Electrically conductive deposits observed in pipes carrying coal seam gas impact cathodic protection (CP) operation and fouling equipment. The deposits are suspected to be a mixture of triethylene glycol and conductive materials such as magnetite and pyrite. This project confirmed the nature of the deposits and  developed potential solutions to reduce their extent and/or impact.

The project findings concluded that the failure of the cathodic protection units of CSG transmission pipeline  to provide adequate protection is due to the presence of highly conductive, solid iron corrosion product contaminants embedded within triethylene glycol on the internal surfaces of pipeline insulation joints. Observations of CSG facilities throughout the project indicate that iron corrosion products are being generated throughout the entire CSG value chain, from upstream steel gathering pipelines to downstream sales gas transmission lines.

The phenomenon of pipeline isolation joints (IJs) failure was also found to be exacerbated by the presence of triethylene glycol, a liquid desiccant used for the dehydration of natural gas. The research also provides mechanisms of IJs failure, deposit generation, and identified mitigation methods.

 

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Commencement / End Date December 2019 to March 2021
Outcomes / Impact

The outcomes of this project assist industry to extend the safe operating life of existing and future assets and minimise industry risk of HS&E incidents, both industry and public.

Two design guideline documents were created to address contaminant production and improve design practices for CSG pipeline systems and gas production facilities. The mitigation methods identified are suitable for both CSG and conventional natural gas, with project findings indicating similar detrimental effects from solid particulates on CP operation in conventional natural gas pipelines. The documents were created utilising a mix of literature information, advice from external specialist consultants and input from the industry advisory team. The documents are composed of the most important recommendations generated by the project and are intended to be the first point of reference for all interested industry participants.

 

Partners University of Melbourne, APA Group, Origin Energy, Santos, Epic Energy
Research Contact

Dr Fari Mahdavi

Research Program Coordinator

E-mail: fariba.mahdavi@futurefuelscrc.com