The mitigation of downhole, dissolved oxygen(DO)accelerated, microbiologically influenced corrosion (MIC) in hydro-fracked, oxygen contaminated, relatively high temperature, unconventionalreservoirs is challenging. Additionally, little research has been published in the area. The mitigation of downhole MICin this type of well is complicated by the reality that mechanical cleaning is not yet possible;therefore, downhole MIC mitigation is solely dependent on chemical applications. DO-accelerated, downhole corrosion is also more difficult to control in high TDS (total dissolved solids) producing wells with complex water chemistries. Furthermore, thehydrofrackingprocess typically introduces oxygenwhichacceleratescorrosion.In this case-study, anoilfield inAlberta, which had been experiencing severe downhole corrosion, was the subject of a comprehensivecorrosion investigation, which identified MIC as the most significant corrosion mechanism.Downhole water chemistry, oxygen contamination levels, ATP determination, and 16S DNA sequencing were used to identify those specific wells which had quantifiable, carbon steel,MIC degradation issues. Several wells had high concentrationsof sulfate-reducing bacteria (SRB) and methanogenic microorganisms as well as elevated dissolved sulfide concentrations. Once the problematic wells were identified, biocide and corrosion inhibitor programs were optimized in cooperation with the client and theiroilfieldchemical provider to effectively mitigate downholecorrosion.16272© 2021 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). 1
Key words: microbiologicallyinfluenced corrosion, sulfate-reducing bacteria,methanogen,dissolved oxygen, downhole tubing, DBNPA, cocodiamine