Materials Selection for High Pressure Sour Service in the Shah Gas Development Project

摘要

Al Hosn Gas Company, a 60/40 JV between ADNOC and Oxy has been undertaking a project for the development of an extremely sour gas reservoir in order to increase production of injection and sales gas. The Al Hosn Gas plant is designed to process 1,000 MMscfd of non-associated sour gas. The gas reservoir is very sour with H2S levels of 23% together with 10% CO2 and other corroding components such as 20,000 ppm chlorides and 5 bbl/MMSCF water. The bottom hole conditions make the overall environment very aggressive for any conventional material e.g. carbon and alloy steels. Processing of such sour feed posed a significant design challenge. Materials selection for production tubular, gas gathering lines and process equipment was the main strategy to ensure plant integrity. The well fluid can reach high temperatures. To protect against external corrosion the carbon steel backing material for flow and trunk lines was coated with high temperature epoxy. Four exotic materials were selected and subjected to 30 days exposure test in autoclave at simulating gas gathering lines conditions. Two materials were further subjected to closer scrutiny with a series of potentiodynamic polarization tests and metallurgical analysis. This paper deals with the materials identification evaluation, test procedures, test details and final selection together with applicable fabrication procedures.