This study reviews the development of a laboratory screening test protocol and electrochemical monitoring and its correlation with known failure and non-failure incidents. It describes the use of C-ring specimens supplemented by electrochemical monitoring of laboratory screening tests using this protocol. These tests evaluated the corrosion behavior of proprietary grades of martensitic stainless tubulars in selected, real-world packer fluid environments which included various high density, clear brine solutions (chloride and bromide salts) in combination with additives. The methodology developed in this study includes the utilization of highly stressed C-ring specimens and the incorporation of an electrochemical device that provided an automated analysis cycle involving three techniques: Linear Polarization Resistance (LPR), Harmonic Distortion Analysis (HDA) and Electrochemical Noise (EN). These techniques were used to identify the corrosion behavior versus time during corrosion tests that lasted from as little as 7 days to 30 days. Data was evaluated based on SCC behavior in C-ring specimens and electrochemical data showing changes in uniform corrosion rate, B value (Stern Geary factor), Pitting Factor and other electrochemical parameters versus time of exposure. The electrochemical data were correlated with post test mass loss corrosion rates, and visual observations of uniform, pitting and local area attack and tendencies for stress corrosion cracking from the C-ring tests. This paper includes tests conducted with air, H2S/CO2 and CO2 cover gases as part of a major research study and tests simulating actual downhole field conditions.

Subject
Environmental cracking, Test methods, Materials, Corrosion rate, Corrosion cracking, Corrosion attacks, C ring stress corrosion testing, Mechanical failure, Fluids, Electrochemical data, Pitting, Electrodes, Pitting factor
Keywords:
Electrochemical monitoring, martensitic stainless steel, packer fluid, completion fluid, halide, brine, pitting, stress corrosion cracking
© 2006 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).
2006
Association for Materials Protection and Performance (AMPP)
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