The use of high density brine is required for High Pressure High Temperature (HPHT) gas condensate wells to ensure safe well operations during drilling and completion phases. Cesium formate brine is one of the latest high-density brine used for this application, being both environmentally friendly and non-corrosive.

The present work investigated the use of high density cesium/potassium formate brine solution at bottom hole environmental conditions for long term exposure periods. In particular the influence of total pressure and temperature on the thermal degradation of the formate-based brine was studied and evaluated.

The results of the testing program demonstrated that thermal decomposition of the fluid occurred, producing a buildup of the internal pressure, in the low pressure tests only, with a development of hydrogen into the gas phase. Furthermore, SCC phenomenon was observed in super martensitic stainless steel samples at certain stress levels together with evidence of hydrogen embrittlement of PH Ni alloy 718. A mechanism for the reactions involved is proposed and discussed.

Subject
Test methods, Decomposition, Materials, Formates, Nickel based alloys, Autoclaves, Gas pressure, C ring stress corrosion testing, Brines, Alloys, Chemical reactions, Stress corrosion cracking, Hydrogen
Keywords:
cesium formate, general corrosion, localized corrosion, Stress Corrosion Cracking (SCC), heavy brines, CRA’s, supermartensitic stainless steel, PH nickel alloys, hydrogen embrittlement, HPHT
© 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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