ABSTRACT
Periodic monitoring by an oil company of hydrogen sulfide (H2S) concentrations in gas samples collected at various locations on an offshore oil production platform indicated that H2S was becoming a pervasive problem that was getting worse in wells that had previously not contained detectable concentrations of H2S. This case study demonstrated that only by obtaining comprehensive data from multiple samples that included H2S quantification, sulfur isotopic ratios in gas and water samples, microbiological data from growth and genetic testing, and water chemistry testing to quantify organic acids was it possible to conclude that there were two sources of H2S in samples from this offshore platform. The oil company now knows that thermogenic H2S is migrating into some oil production zones in this reservoir and that the topside water handling system is vulnerable to microbial contamination, and can plan accordingly.
