Understanding Passive Layer Formation for Further Corrosion Management in Gas Production Pipes

[摘要] Corrosion is a critical issue during the development of a gas field, especially wet gas or retrograde gas field. Corrosion affects the management system of a field and further impacts the amount of investment. Therefore, accurate prediction of corrosion rate is needed to plan an effective preventive action before going further to the development phase. One of the important parameters that should be noticed to create an accurate prediction is the formation of the passive layer. In CO2-H2S environment, there will be three possibilities of passive layer: FeS, FeCO3or no passive layer. In this study, we create mathematical models to determine the formed passive layer in each segment of the gas production tubing and pipeline. The model is built using Faraday's Law and Thermodynamic approach to account the passive layer formation at different temperature, pH, corrosion rate and partial pressure of CO2and H2S. From the simulation, it was found that there were three boundary conditions: no scale-FeS boundary, no scale-FeCO3boundary and FeS-FeCO3boundary. The first two boundaries evolved over a time as the concentration of Fe2+ions was increasing. However, FeS-FeCO3boundary remained steady as it was not affected by the addition of Fe2+ ions. Using sample case study, few variations were noticed at production pipeline and tubing. It was caused by the gas composition, which contained high CO2and very low H2S. Boundary conditions only changed slightly over two days period.

[发布机构] Petroleum Engineering Study Program, Institut Teknologi Bandung, Indonesia^1;Chemistry Study Program, Institut Teknologi Bandung, Indonesia^2

[效力级别] 物理学

[关键词] Accurate prediction;Concentration of fe;Corrosion management;Development phase;Management systems;Preventive action;Production pipelines;Thermodynamic approaches