A sour gas plant was experiencing high corrosion and fouling from aggressive corrosion conditions (170 to 195°F, 170 psi pH2S, 280 psi pCO2) including the presence of elemental sulfur (0.1 wt%). The current chemical program appeared to be ineffective. The operators wanted a new chemical program, including a new corrosion inhibitor (CI) and possibly a new wetting agent (WA) to control corrosion and fouling.
The improvement study included 40 individual wheel bomb studies, which looked at two WAs, eight different CI products, three CI concentrations, and elemental sulfur (granular and powdered) at test temperature. Gas loading of the wheel bombs was performed at room temperature using electrolyte calculations that predicted the final test pressures at the test temperature.
Results showed the WA was marginally effective but only when the CI was at low dosage: Once the CI reached its minimum effective concentration the WAs became ineffective at improving CI performance. Tests using the best performing CI, at 100, 1,000, and 3,000 ppm, showed that the product must be applied above its minimum effective dosage to perform adequately. The best performing CI has a long history in sour, high elemental sulfur fields and it showed insignificant foaming in laboratory tests.
Key words: sour gas field, elemental sulfur, high H2S, high CO2, wheel bomb, high temperature