Five commercial H2S scavengers for drilling fluids were experimentally tested for scavenging ability under various conditions of pH, pressure and temperature. These consisted of both iron and zinc based compounds. Conditions were: pressures of 500 psi, 1000 psi, and 1500 psi, temperatures of 100°F and 200°F, and pH of 6.4 and 12.0.

The zinc reactions were quick, predictable, and irreversible under normal well conditions. The iron scavenger had somewhat higher reactivity (gm H2S/gm scavenger) than most zinc scavengers when tested at pH 12, and much higher reactivities when tested at a pH of approximately 6.5.

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