Research Article

Hydrogeological Controls on Groundwater Contamination from Petroleum Operations: Contaminant Migration, Aquifer Vulnerability, and Assessment Methods

Abstract

Petroleum hydrocarbons enter groundwater from every stage of the oil and gas supply chain, drilling, pipeline transport, refining, storage, and retail distribution, and persist in aquifer systems as free-phase, dissolved, residual, and vapor-phase contaminants for decades after the initial release. How severely a given release affects groundwater depends less on spill volume or operation type than on the hydrogeological properties of the receiving aquifer. This narrative review evaluates the controls that govern that relationship, drawing on field evidence published between 2010 and 2025 from Scopus, Web of Science, and Google Scholar. Four domains are addressed: contaminant migration and fate, including multiphase flow behavior and natural source zone depletion rates measured across 40 petroleum sites at a median of 9,540 L/ha/yr; aquifer vulnerability assessment, comparing DRASTIC, GOD, and physically based transport models across alluvial, karst, and fractured settings; hydrogeological controls on contamination severity, with depth to the water table, lithology, fracture connectivity, and water table fluctuation identified as the dominant factors; and field assessment and monitoring methods, from standard hydrochemical indicators through compound-specific isotope analysis and geophysical imaging. Index-based vulnerability frameworks provide useful regional screening but produce vulnerability estimates differing by a factor of four when multiple models are applied to identical input data, and none account for the temporal evolution driven by biodegradation. Site characterization that pairs index screening with multi-parameter field investigation, hydrochemistry, redox profiling, isotopic analysis, and geophysical spatial coverage, would bring routine practice closer to the level of understanding that the available science already supports.