1-3 Risks Posed by Salt Walter Disposal Wells in Legacy Oil Fields

Session: Energy Geology

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Injection of produced water into geologic formations in areas with legacy oil fields poses a complex and often underestimated threat to groundwater because decades-old wells, many drilled before modern casing and cementing standards, can act as preferential pathways for upward migration of pressurized fluids. When large volumes of saline, chemically altered produced water are injected, subsurface pressures increase and can drive fluids along corroded casing, degraded cement, or abandoned wellbores that were never properly plugged, allowing contaminants such as chlorides, hydrocarbons, metals, and naturally occurring radioactive materials to reach freshwater aquifers. These risks are amplified in mature oil fields where well density is high and historical records of well locations and construction are incomplete, making it difficult to identify and remediate all potential leakage points. Even when injection occurs thousands of feet below freshwater aquifers, vertical hydraulic connectivity created by old wells and boreholes can short-circuit the geologic confining layers that normally protect groundwater. Over time, small but persistent leaks can degrade water quality in aquifers that supply rural domestic wells and municipal systems, with contamination that is extremely difficult and costly to detect, trace, and remediate. As produced water volumes continue to rise with unconventional oil and gas development, the cumulative risk posed by legacy infrastructure in these older fields becomes a critical issue for groundwater protection and long-term water security.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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