The Karan offshore development is expected to produce a large quantity of natural gas but no hydrocarbon condensate. Liquid water is, however, projected to be present through condensation and the presence of CO2 (8%) and H2S (4%) will lead to aggressive corrosion environments. Different inhibition techniques will be implemented to control bottom of the line corrosion. Top of the line corrosion (TLC) is also a potential issue in specific locations in the field as large quantities of organic acids are present in the produced water. This paper presents a comprehensive assessment of the corrosion risk through laboratory simulations performed in a large scale flow loop as well as in a specially designed autoclave equipped for corrosion studies under dewing conditions. Corrosion rates are obtained through weight loss methods and the surface layer is analysed with XRD (X-ray diffraction), EDS (Energy Dispersive Spectroscopy) and SEM (Scanning Electron Microscopy). The TLC rate was found to be low in all conditions tested and no indications of localized corrosion was observed. Mackinawite, cubic iron sulfide, and troilite (stoichiometric pyrrhotite) were identified in the corrosion product layer. The results are used to guide the required corrosion management measures, which are also presented.

Subject
Steel surfaces, Water, Mackinawite, Flow loop, Corrosion rate, Iron sulfides, Autoclaves, Top of the line corrosion, Condensation rates, Partial pressures, Corrosion products, Surface layers, Steel
Keywords:
Top of the line corrosion, H2S, CO2, Water condensation rate
© 2012 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).
2012
Association for Materials Protection and Performance (AMPP)
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