Microbial inhibition of sulfate reduction using nitrate and nitrite addition: a laboratory study of reservoir souring control

Abstract

Microbial sulfate reduction produces unwanted H₂S in oil and gas reservoirs (i.e., reservoir souring) when seawater is used in secondary oil recovery. Previous studies have shown that the addition of nitrate and/or nitrite can inhibit sulfate reduction, but the effects are site-specific. In this thesis, seawater and produced waters were sampled offshore Newfoundland and Labrador (NL) for three incubation experiments to determine the affect of nitrate and/or nitrite addition on microbial sulfate reduction. Of the three amendments tested (i.e. just nitrate, just nitrite, and a combination of the two) all were successful at inhibiting sulfate reduction. No one type of amendment inhibited microbial sulfate reduction better than the others; however, nitrate showed potential of having a longer residence time, and therefore nitrate maybe an ideal choice for the inhibition of microbial sulfate reduction for offshore NL.