A Development Company in Oman, operates an extensive and ageing oil pipeline system to transport dehydrated oil from many fields in Oman to the terminal at the coast. Except for some particular pipeline sections, the main corrosion problems are internal and this requires continuous attention. Regular intelligent pigging has shown that internal corrosion is more prominent in certain sections of the line and different corrosion mechanisms seem to occur.

Typically the mechanisms vary from CO2 corrosion, CO2/H2S corrosion, oxygen corrosion and bacterial corrosion. Where in the past most severe internal corrosion occurred in the flowlines and gathering systems, also due to oxygen ingress, reservoir souring and acid well stimulation jobs, application of non-metallic pipe and liners in the gathering systems over the last 10 years seems to have shifted the corrosion problems downstream to the Main Oil Line which now requires additional mitigation.

Additional causes arise from water wetting by process upsets, re-injection of reclaimed fluids and treated sludge and local oxygen ingress. Other problems occur at third party tie-ins where the introduction of corrodents in the system may be poorly controlled. This paper describes some of the experiences gained in understanding the driving corrosion mechanisms and the actions taken to effectively mitigate degradation.

Subject
Water, Intelligent pigs, Pipelines, Inspection, Fluids, Dehydration, Internal corrosion, Oxygen, Pigging, Oxygen corrosion, Corrosion mechanisms, Microbiologically influenced corrosion, Oil
© 2005 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).
2005
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.