Contamination by Repressuring of an Oil Field

Wilmoth (1972) reported that a domestic well in Kanawha County, West Virginia, USA, contained only 32 mg Cl/l until 1967. This excellent water quality deteriorated because of brine injected into an adjacent oil well. Within 1 year the chlorine concentration rose to 1140 mg/l (Fig. 16.13). Operations were stopped and the chlorine concentrations decreased slowly, reaching a value of 450mg Cl/l early in 1971, and the well could be used once more. The decrease in chlorine was caused by natural flushing of the water flowing in the aquifer.

A second case described by Wilmoth (1972) in the same country related to a fresh water aquifer near Wallace that contained 100 mg Cl/l. In late 1967 injection of brines, as part of subsurface operations in an adjacent oil field, caused an increase to 2950 mg/l chlorine concentrations within 2 months. Operations were stopped and the water quality was soon restored, attaining concentrations of 190mg/l after 2.5 years (Fig. 16.14).

Fig. 16.13 Changes in chloride in a contaminated well adjacent to an oil field, Kanawha County. Fast response to brine injection in a nearby well was observed, as well as fast recovery after brine injection was stopped. (Following Wilmoth, 1972.)

1967 1968 1969 1970

Fig. 16.14 Changes in chloride in a contaminated well adjacent to an oil field, Kanawha County. Injection of brines into nearby wells caused a dramatic increase in chlorine, which was cured in 2 years. (After Wilmoth, 1972.)

1967 1968 1969 1970

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