51314-3808-Corrosion Management and Cleaning of SAGD Produced Gas/H2S scavenger Contactor

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Product Number: 51314-3808-SG

ISBN: 3808 2014 CP

Author: Qiang (John) Liu

Publication Date: 2014

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Produced gas from the Steam Assisted Gravity Drainage (SAGD) recovery process typically consists of approximately 6% mercaptans and 8000 ppm H2S. This sour gas is sweetened using an H2S scavenger in a carbon steel (CS) contactor. Operating experience showed that the original plastic pall rings installed in the contactor were susceptible to damage while in service. Therefore 304 stainless steel was selected as an alternative pall ring material. The potential for galvanic corrosion was investigated since the proposed stainless steel pall rings would be supported on the original carbon steel stands in the contactor. A corrosion monitoring program was also established including water chemistry analysis and internal inspections.To prepare for the installation of the new pall rings the contactor tower needed to be thoroughly cleaned to remove several years of built up solids. Hydrogen peroxide (H2O2) is typically used for this purpose to remove mercaptans and to oxidize other sulfur containing compounds. The previous contactor cleaning with H2O2 at 80 ºC resulted in the generation of hazardous oxygen from H2O2 decomposition and the release of H2S. The new procedures that were developed with optimized cleaning temperature (30 to 35 ºC) and pH (5 to 6.5) ensure effective removal of mercaptans significant decrease in H2O2 decomposition and mitigation of corrosion on the metal.This paper discusses the successful application of these procedures as well as the results of the corrosion monitoring program.Key words: SAGD galvanic corrosion hydrogen peroxide oxidation decomposition mercaptan produced gas H2S scavenger contactor