ABSTRACT
Declining reserves of conventional crude and increased reliance on high-sulfur feedstocks are intensifying environmental and operational challenges across petroleum infrastructure. To investigate a primary consequence – microbial souring – we conducted a comprehensive survey of topside water streams at a Central Arabian oil field, employing both culture-based and culture-independent enumeration, 16S rRNA gene sequencing, biostatistical analysis, and detailed chemical profiling. Chemical tests revealed distinct hydrogeochemical regimes across processing units, with significant variation in microbial abundance and diversity between sites. Sulfate-reducing bacteria were notably prevalent in critical facilities. Mesothermal process waters enriched in sulfate and organics proved especially susceptible to hydrogen sulfide-producing microorganisms, posing a risk of severe souring if left unmanaged. Conversely, thermal produced waters with comparable chemistry exhibited sparse microbial populations, underscoring the protective effect of elevated reservoir temperatures. Importantly, more than 80% of surface samples fell outside the criteria for bioburden or souring, indicating potential vulnerabilities despite effective reservoir control. These findings highlight the need for integrated chemical and microbiological monitoring, together with adaptive biocide strategies, to protect both surface operations and underground resources.
