Mitigating Sulfate-Reducing Bacteria in Produced Water: Performance of MB-X Biocide Assessed by SRB‑BART at a Mature Onshore Asset

PERFORMANCE OF MB-X BIOCIDE

Abstract

Sulfate-reducing bacteria (SRB) are major drivers of microbiologically influenced corrosion (MIC) and reservoir souring in waterflooding operations, particularly in mature onshore assets with high produced-water volumes. This is showing the need for effective control of SRB to mitigate potential risks and maintain the integrity of waterflooding operations. Therefore, this study is aiming to evaluate the efficacy of the biocide MB-X at multiple doses (50-200 ppm) in suppressing SRB activity and population using the SRB-BART (Biological Activity Reaction Test). The experiment is being conducted by collecting produced-water samples from the Outlet WT at Field MX, followed by daily monitoring of SRB activity to determine the reaction day. The data obtained are being converted into population estimates (CFU/mL) according to the commercial kit guidance: Day-3 = 1.15 × 10⁵ CFU/mL; Day-4 = 2.7 × 10⁴ CFU/mL; Day-10 = 5 CFU/mL; Day-11 < 1 CFU/mL. Aggressiveness is being classified according to the kit scoring, namely Aggressive, Not Aggressive, and Negative. The results are showing that the control (blank) is showing a BB-type SRB consortium (anaerobe-dominant), with 1.15 × 10⁵ CFU/mL being classified as Aggressive. MB-X 50 ppm is reducing the population to 2.7 × 10⁴ CFU/mL, but the response is remaining Aggressive. In comparison, MB-X 100 ppm is suppressing counts to 5 CFU/mL (Not Aggressive), while MB-X 200 ppm is yielding a Negative response, showing undetected SRB activity. These results are indicating that MB-X at ≥100 ppm is effectively controlling SRB under test conditions, with 200 ppm achieving apparent eradication as detected by SRB-BART. However, interpretation of the statistical outcomes is being constrained by the limited number of treatment replicates, suggesting that the results should be considered a preliminary site-specific evaluation of MB-X performance. Consequently, future studies are being recommended to conduct field verification through replication, matrix controls, and in-situ corrosion monitoring to confirm performance durability.