Esso Australia is a supplier to the Australian Eastern Gas Market, responsible for a significant proportion of energy to the residential, commercial and industrial markets. Historically, this was met through low carbon dioxide (CO2) supplies. Over time, new supplies blended higher CO2 fields into the existing low CO2 stream. As the field matures and the lower CO2 fields deplete, the proportion of CO2 has increased. Offshore gas compression has been installed to boost gas production rates, which increases the export gas temperatures. The Longford Gas Conditioning Plant was installed and commissioned to process the additional CO2 prior to sale to the gas transmission network. However, the increasing CO2 and higher raw gas pipeline inlet temperatures have the potential to increase top of line corrosion (ToLC) risks to the associated gas flowlines. This paper documents the technical evaluations undertaken to assess ToLC risks on Esso Australia’s gas production network. The evaluation included (1) a literature review against existing standards and latest industry research literature covering CO2-induced ToLC mechanisms, (2) development of a ToLC screening tool, and (3) development of OLGA simulations to assess whether existing controls were sufficient in controlling ToLC risks. The results were compared to recent in-line inspection data and have determined that, provided certain process monitoring limits are maintained, ToLC risks can be controlled until end of field life. The evaluation may be useful in assessment of existing gas production networks subject to increasing CO2 compositions and used as inputs into integrity management plans.
David Levy (Wed,) studied this question.