A new iron-based, environmentally friendly hydrogen sulfide scavenger for drilling fluids

A new scavenger has been developed that relies on the affinity between iron and sulfide. The active chemical is a form of ferrous iron complexed with a carbohydrate derivative. It is highly soluble in the brine phases of water-based mud (WBM) and will not precipitate at pH values greater than 12. When the iron is in solution, the reaction with sulfide is instantaneous and complete. This paper deals with the environmental implications of zinc vs. iron and the development of the new scavenger. It presents details of case histories concerning operations on a reservoir containing 25% hydrogen sulfide (H2S). Even in these demanding conditions, there was no H2S at surface.