Sweet corrosion by the presence of carbon dioxide (CO2) in petroleum production was studied in a high pressure recirculating flow loop containing brine and/or hydrocarbon phases. This study was focused on flow enhanced corrosion and its inhibition by chemical treatment. Presence of hydrocarbon decreases corrosion rates. No precipitous drop in corrosion rate was found at the phase transition ratio; instead, a smooth decrease was observed with increasing hydrocarbon-to-brine ratio. Presence of a small amount of water, even at less than 5%, can lead to considerably high corrosion rates provided that the oil is light and the flow condition is severe. The degree of flow enhancement was also investigated, which showed over 50% contribution to the overall corrosion rate in some severe cases. In order to control flow enhanced corrosion, a special group of shear resistant corrosion inhibitors has been developed. The laboratory tests demonstrate that these inhibitors are quite effective for continuous treatments and/or batch applications. The enhanced performance is attributed to the improvement in adsorption kinetics and film persistency. Good correlation has been obtained between laboratory results and field testing. Flow enhanced corrosion can occur as general corrosion and/or a localized attack. General corrosion was observed in most cases irrespective of inhibitor treatments. One example illustrates significant localized corrosion (pitting) in an inhibited system despite a reduction in the general corrosion rate. This example stresses the importance of proper inhibitor evaluation for the control of flow enhanced corrosion.

Subject
Water, Flow loop, Corrosion rate, Flow velocity, Adsorption, Pipelines, Shear, Fluids, Corrosion inhibitors, Corrosion probes, Corrosion protection, Corrosion resistance, Oil
Keywords:
flow loop, erosion, corrosion, oilfield, inhibitors, flow enhanced corrosion
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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