Accurate forecasting of oilfield souring is vital for the oil industry. Souring (an increase in concentration of toxic hydrogen sulphide) increases the cost of maintenance and repairs four-fold, and reduces the value of crude oil by up to 20%. Our research led to development of the World’s first predictive models for the souring of oil-wells. The implementation of the models in software, commercialised by Rawwater Engineering Limited, provides accurate forecasts and has been validated by major Operators, including BP, Shell and Chevron. Since 2008, twelve different Operators have used the models in souring management, which has led to an estimated cost saving of US$360m since 2008.