After preliminary screening of the inhibition characteristics and performance of 5 corrosion inhibitors (designated A, B, C, D, & E) under simulated CO2/H2S environment in the HT-HP flowing autoclave, the best two corrosion inhibitors (corrosion inhibitors A & B) were selected for further flow loop testing under simulated North Sea pipeline service conditions.

The worst case pipeline service conditions (90% synthetic field brine/10% hydrocarbon (depolarized kerosene) environment with H2S (partial pressure 0.075 psia [0.5 KPa]) and CO2 (partial pressure 75 psia [0.5 MPa]) were simulated at 300° F. (149° C.) in a laboratory flowloop and the performance of the selected corrosion inhibitor formulations A & В on API 5L X-65 carbon steel and 0.5 percent Cr X-65 steel were evaluated at two concentrations (100 ppm and 250 ppm by volume). The corrosion rates were monitored at stirred (reservoir), laminar and turbulent flow regimes at wall shear stresses corresponding to a range of velocities (4.2, 5.3, 6.3, 7.0, 7.9, 13.1, 15.4, 17.4 and 21.1 ft/sec) using linear polarization (LPR) and weight loss techniques.

The test results indicated the following:

  • Provided the proper concentration of corrosion inhibitor is applied continuously, carbon steel can be satisfactorily inhibited under laboratory test conditions that simulate pipeline worst case corrosion conditions.

  • Corrosion inhibitor "B" was not as effective as corrosion inhibitor "A" requiring about 2.5 times as much "B" as "A" to accomplish the same level of corrosion control under these simulated laboratory test conditions.

  • The results of this corrosion inhibitor evaluation program do not support the use of 0.5 Cr X-65 material over X-65.

  • The flowloop test data obtained at higher wall shear stresses indicated, within the limits of the wall shear stress parameters, there was little or no effect on the corrosion inhibitor film being laid down continuously on the metal surface.

Subject
Materials, Inhibitor performance, Modeling, Flow loop, Corrosion rate, Impingement, Autoclaves, Wall shear stress, Pipelines, Reservoirs, Corrosion inhibitors, Steel, Electrodes
Keywords:
Environmental flowloop testing, Corrosion inhibitor evaluation, Laboratory testing of corrosion inhibitors, CO2/H2S corrosive environment
© 1997 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).
1997
Association for Materials Protection and Performance (AMPP)
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