Innovative Approach for Assessing the Spatial Distribution and Environmental Impact of Fugitive Gases in Subsurface Aquifers at Oil Fields

Abstract Fugitive gases, also known as "stray gases," are naturally occurring gases released from oil refining and storage facilities. They can potentially contaminate groundwater aquifers near oil and gas fields. Despite their environmental significance, limited research has been conducted to investigate the extent of contamination caused by these gases. This study aims to investigate the presence, spatial distribution, and potential sources of fugitive gases in the groundwater of Kuwait's oil fields. Groundwater samples were collected from the northern, southeastern, and western regions of Kuwait's oil fields and analyzed for major and minor ions, trace elements, fugitive gases, and isotopes of methane (CH4) and noble gases. Fugitive gas concentrations were highest in the northern Kuwait oil field, while hydrogen sulfide (H2S) was more commonly detected in the southeast. Ethane (C2H6) was detected in a few samples, with the highest concentration observed in the northern region. Spatial analysis indicated that hydrocarbon gases migrate from oil fields through structurally weak zones into shallower aquifers. Isotopic analysis of methane (δ13C and δ2H) confirmed a thermogenic origin with no microbial biogenic signatures, with δ13C variations likely linked to the maturity of the source rock. The principal component analysis (PCA) identified a relationship between total organic carbon (TOC), pH, and C2H6 concentrations in groundwater. The study concludes that the distribution of fugitive gases is governed by pressure, temperature, conductivity, and subsurface structural features. Spatial distribution maps generated using GIS highlighted hotspots of higher gas concentrations in northern and western Kuwait, correlating with dissolved helium levels, while southeastern Kuwait showed lower concentrations. This study introduces a novel approach to assessing the occurrence and impact of fugitive gases in groundwater. It recommends further monitoring of additional wells in northern and western Kuwait, along with additional isotopic analysis and correlating these findings with subsurface structures.