In recent years, there have been some failures at Pirital and Santa Barbara oilfields. The main cause of failures has been identified as CO2 corrosion associated to light crude oil production at low water cuts. Some wells in this field had never experienced any corrosion related failure, in contrast to other ones of similar characteristics that had recurrent failures in the production pipeline. This phenomenon had generated an interest since 1999 to study the natural inhibition properties of some crude oils in that area.

The study began with well PIC-4C that showed a decrease in the corrosion rate in presence of the oil, for different crude/water rates1 . The inhibiting property of the oil was associated with crude composition, emulsion stability between the crude and the water phase, wettability, etc 2 . For this reason, it is important to identify other wells in Pirital and Santa Barbara oilfields, with similar characteristics to PIC-4C in order to understand the corrosion inhibition mechanism of this crude. Wells were selected for the study according to the production sand at Pirital and Santa Barbara oilfields.

Additionally, the corrosion rate at different wells was assessed using the prediction program. Samples of selected crude, based on the predicted data, were further studied in laboratory tests, in which the key corrosion parameters (e.g., CO2 and H2S partial pressures, total pressure of the system, temperature and flow dynamics) were varied. The corrosion rates predicted by CO2 corrosion prediction program were wells containing the highest water cut and CO2 partial pressures. However, the laboratory test results showed a different trend, which suggests the crude property is more important.

Subject
Chemical compounds, Water, Corrosion rate, Metal surfaces, Partial pressures, Reservoirs, Corrosion products, Oilfields, Crude, Pitting, Corrosion potential, Resins, Oil
© 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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