Comparative analysis of the efficacies of ferrous gluconate and synthetic magnetite as sulphide scavengers in oil and gas drilling operations

Two environmentally safe iron compounds (synthetic magnetite and ferrous gluconate) have been evaluated as sulphide scavengers at temperature conditions of 25 °C, 35 °C, 45 °C and 55 °C at pH of 12 in a sulphide-contaminated drilling mud. The ferrous complex was found to be a better scavenger than synthetic magnetite. It exhibited 100 % scavenging efficiency within the first 40 minutes of agitation. The same concentration of the reagents, which is 700 mg/l scavenger vs. 700 mg/l sulphide, was employed (i.e. sulphide concentration to scavenger concentration ratio was 1:1). Whereas, the synthetic magnetite’s scavenging efficiency was only about 30% even after 2 hours of agitation. Addition of the ferrous complex to the drilling mud was not found to be detrimental to the rheological properties of the mud. Its inclusion brought about the stabilization of mud’s rheological properties.