Abstract: The application of oil displacement agent in cementing pad fluid is a new technology,and a novel biological cementing pad fluid is developed,with excellent drilling fluid flushing and displacement efficiency.This biological cementing pad fluid is developed based on the study of such physical and chemical properties as surface tension reducing,corrosion,pH value,density and suspension of the flushing fluid and spacing fluid mixed,as well as its compatibilities with various drilling fluids and cementing slurries used in Shengli Oilfield.Field cementing application showed that it has good flushing,displacement and replacement properties,and the bonding quality on cementing interfaces was improved,thus greatly improved the cementing quality.