This paper presents a methodology for designing field tests to assess the relative performance of inhibitors and other chemical products, which are used to control corrosion associated with crude oil production. The same corrosion inhibitor injection points and corrosion monitoring points can be used for (1) routine operations, and for (2) field performance tests of candidate products. Field tests, which assess the performance of individual products for three phase fluids or wet gas production, require precise step changes in the chemical treatments rates in order to accurately determine the minimum quantity of inhibitor for attaining a pre-established level of performance. The approach to field-testing is applicable to all production fields. However, the candidate products must be selected, based on the chemistry of the produced fluids, including the concentration of CO2.

Downhole corrosion inhibitor treatments were also discussed. Although downhole monitoring evidenced extremely short treatment lifetimes at one field, the results cannot be construed to mean that treatments elsewhere would be ineffective. An approach was provided to enable monitoring at the wellhead to be able to assess the performance of downhole tubing displacement treatments. The use of corrosion modeling software was discussed, and comparisons were made with previously published measurements of downhole corrosion rates. Reasonable agreement was observed. However, better comparisons could be obtained with more precise and more current measurements of the process parameters and the compositions of the produced fluid and gas.

This paper also emphasized the need to quantify the concentration of biocide treatment, which arrive at the remote locations in the produced water or seawater injection systems. The concentration must be sufficient as to be effective. The application of downhole scale inhibitors was also discussed. The chemistry of the produced water, natural gas, and the injected seawater must be known in order to properly select the best candidate products, since the dissolved carbon dioxide can make a tremendous impact upon the pH, and the ability of the products to properly adsorb and slowly desorb, thereby providing scale inhibition. This paper also emphasizes the selection of the candidate chemical products, based on measured cost-performance.

Subject
Water, Inhibitor performance, Corrosion rate, Pipelines, Solubility, Tubing, Fluids, Inhibitor treatment, Corrosion inhibitors, Corrosion probes, Biocides, Corrosion monitoring, Oil
Keywords:
Corrosion, Inhibition, CO2, Performance Testing, Field Tests, Crude Oil, Natural Gas, Monitoring, Downhole Corrosion, TOL
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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