Produced gas (PG) from the Steam Assisted Gravity Drainage (SAGD) recovery process typically consists of approximately 6% mercaptans and 7,500 ppm H2S. This sour gas is sweetened using a triazine H2S scavenger in a carbon steel (CS) contactor. The reactions between the scavenger and H2S were studied for operation optimization. A corrosion management program was established in PG lines and contactor including water/gas chemistry study and coupon monitoring.

To keep the high contact efficiency of H2S and the scavenger, the contactor required thorough cleaning to remove several years of built up solids. A commercial hydrogen peroxide (H2O2) incorporating a stabilizer to reduce its decomposition in the presence of metal ions is used for mercaptan removal and oxidizing other sulfur containing compounds. The first contactor cleaning with H2O2 at 60°C (140°F) resulted in the generation of hazardous oxygen from H2O2 decomposition and the release of H2S. New procedures developed with an optimized cleaning temperature of 30°C (86°F) and a pH of 8.0 ensured the effective removal of the mercaptans, a significant decrease in H2O2 decomposition, and the oxidation of polysulfide for corrosion mitigation.

This paper discusses the successful application of these procedures as well as the results of H2S scavenger reactions and the corrosion monitoring program.

Subject
Sulfur, Decomposition, Water, Thiols, Corrosion rate, Triazines, Corrosion reactions, Acidity, Amines, Polysulfides, Elemental sulfur, Chemical reactions, Cleaning
Keywords:
SAGD, triazine, corrosion rate, H2O2, oxidation, decomposition, mercaptan, produced gas, H2S scavenger contactor
© 2014 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2014
Association for Materials Protection and Performance (AMPP)
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