Internal corrosion occurs only when corrosive water wets the pipe inner wall. However, water wetting is one of most important missing links of our current overall understanding of internal corrosion of oil and gas pipelines.

In this study, extensive experimental studies on water wetting in large diameter horizontal oil-water pipe flows were carried out. Four main techniques (wall conductance probes, Fe2+ concentration monitoring, wall sampling and flow pattern visualization) were used to determine phase wetting on the internal wall of pipe at different superficial oil and water velocities. Four flow patterns were observed: stratified flow, stratified flow with mixed layer, semi-dispersed and dispersed flows. Three types of phase wetting regimes (water wetting, intermittent wetting and oil wetting) were determined. A comprehensive phase wetting map was obtained based on the overlapping information from these techniques.

Based on the results of corrosion monitoring, it was found that a complete absence of corrosion is guaranteed only when oil wetting occurs. At the same superficial oil velocity, the corrosion rate under water wetting is much higher than that under intermittent wetting. Phase wetting significantly affects the corrosion rate.

A comparison was carried out between the mechanistic water entrainment and separation model8-9 and experimental results. A good agreement was achieved.

Subject
Flow patterns, Water, Piping, Droplets, Probes, Flow velocity, Walls, Wetting, Mixtures, Phase wetting, Fluids, Sampling, Oil
Keywords:
experimental study, water entrainment, water wetting, CO2 corrosion, oil-water flow
© 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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