This paper presents some of the findings from a joint industry research program supported by major oil and gas producers, coiled tubing (CT) manufacturers and material producers. Phase I of this program determined the cracking resistance of CT material in wet H2S environments which included a database of field failure scenarios. In Phase II of this program, cyclic fatigue tests were conducted on specimens pre-exposed to aerated brine, sour brine, sweet brine, and stimulated acid service environments. Tests showed that the duration of exposure in aerated brine and sour brine environments did not affect the average number of cycles to failure. There was no significant difference among the different grades of coiled tubing in each separate environment. However, exposure to the evaluated environmental conditions severely decreased the fatigue life of the coiled tubing in comparison to the as-received (control) set of samples.

Subject
Acids, Test methods, Corrosion fatigue, Materials, Sour environments, Aqueous environments, Stimulation, Sour brine, Mechanical failure, Brines, Coiled tubing, Fatigue, Sulfide stress cracking
Keywords:
coiled tubing, serviceability, workover environment, production environment, sulfide stress cracking, SSC, sour service
© 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)
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