Siliceous scaling deposition from geothermal brine is recognized as detrimental to the smooth operation of steam generation and brine injection facilities; the control of such deposition is costly and poorly understood. Scales normally encountered in geothermal wells are often different from the conventional cases. Silica (amorphous and colloidal) and poorly crystallized metal silicates are the most common scale types in geothermal applications.

There are a number of ways to control this type of scaling, including both engineering (e.g. maintain pressure and temperature) and chemical means (e.g. controlled precipitation and inhibition). This paper will focus on preventive techniques by the use of chemical inhibitors.

Currently, there are no standard or generally accepted laboratory test methods to study these types of fouling problems. However, using a low-pressure test method and testing apparatus, we were able to rank the scaling inhibition performance of several generic chemicals. Furthermore, the chemical was successfully packaged into formulations that were suitable to a specific geothermal well condition where large amounts of iron were present, complicated by the co-deposition of barium sulfate scale. The mechanisms of silica/metal silicate scale formation and inhibition, including the verification test using a high pressure, high temperature (HPHT) apparatus for this geothermal application, are discussed in this paper.

Subject
Test methods, Geothermal energy, Materials, Materials performance, Silicates, Scale inhibitors, Silica, Metals, Inhibition efficiency, Corrosion inhibitors, Scale, Brines, Scaling
Keywords:
silica scale, scale inhibitor, prediction software, modeling, geothermal
© 2013 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).
2013
Association for Materials Protection and Performance (AMPP)
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