Evaluation of Non-oxidizing Biocides to Control Sulfate-Reducing Bacteria on a Produced Water Injection Plant Matilde F. de Romero £ , Lisseth Ocando, Antonio De Turris Universidad del Zulia - Centro de Estudios de Corrosión, Maracaibo-Venezuela. £ INCORS, Lima-Perú. Laura L. Machuca Curtin University - Curtin Corrosion Engineering Industry Centre. Australia. ABSTRACT This study shows the procedure used for evaluating the effectiveness of a variety of non-oxidizing biocides for controlling microbiologically influenced corrosion (MIC) by sulfate reducing bacteria (SRB) in a water injection plant of a Venezuelan oil company. A laboratory screening of 15 biocides was completed against sessile SRB on carbon steel surfaces at the maximum concentration established by the manufacturer and two hours as contact time. This evaluation permitted a reduction of the options to four biocides. Results showed that a good method for growing biofilms and evaluating the efficiency of biocides in laboratory was the use of produced water with a 10% inoculum of a fully grown SRB culture originating from the field system. Keywords: Non-oxidizing biocides, MIC, sessile SRB, produced water. INTRODUCTION Microbiologically influenced corrosion by SRB is one of the principal problems that affect the oil and gas industry. The most affected systems are those related to secondary oil recovery and injection water, which are generally contaminated with this bacterial group. It is well known that elimination of microorganisms from these ecosystems is very difficult since they can be indigenous to the same formation or can enter the system during the early stages of exploration. Therefore, the practical alternative to handle these problems is by the application of non-oxidizing biocides, to maintain under control the levels of sessile bacteria so that they do not represent a threat for internal corrosion. 1 Nowadays, there is a great range of compounds within this group of non-oxidizing biocides that are effective at certain specific conditions, but not in others; thus, their efficiency should be evaluated before its actual application in the field. The effectiveness of the biocides against planktonic populations 1 Paper No. 5793 ©2015 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 15835 Park Ten Place, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association.