It is well understood that sulfate reducing bacteria (SRB), acid-producing bacteria (APB), and facultative anaerobic bacteria may cause a range of problems in oil and gas applications including the production of hydrogen sulfide (souring), microbially influenced corrosion (MIC), and additive spoilage. These problems may ultimately reduce the quality of the hydrocarbon produced, decrease the durability of structural assets, and accelerate formation damage. Microbial contaminants may originate from poorly treated source waters and process fluids (e.g., drilling fluids) as well as resident organisms existing in the subsurface environment.

The antimicrobial performance of oil and gas biocides is dependent on their stability and compatibility with key environmental parameters in applications such as hydraulic fracturing and water flooding. For an extended microbial control program, the biocide must survive and function under varying conditions. The most aggressive conditions involve the downhole environment where temperature and salinity extremes may occur and reactivity with the substrata (rocks, mineral, soil, hydrocarbons) create a complex set of interacting influences.

This study investigated the interactions of several oil and gas biocides in the presence of subsurface rock matrices (Berea sandstone). The effect of the rock on biocide adsorption was determined analytically and the resulting impact on residual efficacy was assessed by microbial viability. Certain actives were more adsorptive to solid rock substrata than others. Cationic (surface active) biocides with long-chain hydrophobic moieties were shown to rapidly bind to Berea sandstone rock and be removed from the water phase, resulting in a loss of antimicrobial efficacy. Non-surface active biocide chemistries showed better compatibility and resulting efficacy after contact with subsurface materials (sandstone rock). For the adsorptive biocides, high levels of rock (1:1 rock to water ratio) resulted in complete loss of efficacy. The results of these studies provide insight and guidance into the selection and use of oil and gas biocides for downhole applications, where compatibility with complex environmental parameters is required in order to provide long-term extended microbial control.

Subject
Stability, Sandstone, Water, Materials, Rocks, Adsorption, Oil and gas, Efficacy, Corrosion losses, Bacteria, Glutaraldehyde, THPS, Biocides
Keywords:
Biocide, water flooding, hydraulic, fracturing, oil, shale, glutaraldehyde, ADBAC, DBNPA, THPS
© 2016 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).
2016
Association for Materials Protection and Performance (AMPP)
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