Selection of geothermal energy resources for development has historically targeted moderate temperature near neutral to alkali brines having low to moderate H2S concentrations. Conservative energy generation processes that minimized the risk of scaling were used and materials selection rules of thumb were developed to ensure long service lifetimes for energy equipment: avoidance of air ingress, use of suitable stainless steels for more demanding service and for corrosive steam condensates and use of low strength steels for H2S service.

These traditional rules of thumb for process and materials selection are being augmented for more aggressive acidic environments encountered in some geothermal fields, in Engineered Geothermal Systems and in new energy extraction processes designed to improve efficiency through utilization of geothermal fluids to lower temperatures. In addition, near magma and volcanic environments are challenging 21st century developers now in the same way as geothermal steam and two-phase fluids challenged the pioneers of geothermal energy in Italy, New Zealand Japan and around the world in the middle of last century.

This paper describes some of the materials and process challenges facing geothermal energy developers targeting efficiency improvements and extremes of aggressive geothermal fluid chemistries and temperatures.

Subject
Acids, Geothermal energy, Materials, Materials selection, Solids, Silica, Reservoirs, Acidity, Fluids, Brines, Steam, Scaling, High temperature
Keywords:
Geothermal, Materials Selection, Production Extremes, Solids, Acids, High Temperatures, Risk Based Assessment
© 2017 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).
2017
Association for Materials Protection and Performance (AMPP)
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