Contamination of groundwater from oil field water disposal pits in Kuwait

الملخص EN

The infiltration of the off-specification seawater, used for injection in oil reservoirs, and brines produced with oil that were disposed in lined or unlined pits in the oil fields of north Kuwait.

To observe any changes in groundwater salinity due to the discharges to the pits, four monitoring wells were drilled around one of the lined pits and one monitoring well was completed in the vicinity of an unlined one.

The salinity of the water samples recovered from these wells was monitored.

The peak values of total dissolved solids (TDS) in the monitoring wells to the north of the lined pit reached 57,000 mg / L and that for the well to the north of the unlined pit 45,000 mg / L.

During the observation period of almost one year, the values came down to 3000–5000 mg / L and 37,600 mg / L, respectively.

The measurements, thus, suggested that the water disposed in both pits was infiltrating the water table.

Numerical modeling has indicated that saline water plumes created by this infiltration move 80–85 m northeast down the prevailing hydrodynamic gradient over a period of 5 yrs.

If, however, high-rate pumping from the nearby freshwater field of Raudhatain to the west is to reverse the direction of the hydraulic gradient in the future by lowering the prevailing potentiometric head at the western boundary of the modeled area by 1.5 to 2m, these plumes will move towards the freshwater body by about 100 m over a period of 5 yrs.

and pose a danger to the integrity of the resource.

It has, therefore, been recommended that all disposal pits within the perimeter or in close proximity to the freshwater basin (depression) be closed down and that new ones are located outside and away from the depressions.

Adoption of other environment-friendly means of disposal (e.g., injection in deep aquifers) should also be considered.