Global Oilfield Chemicals Market Size study, by Type (Biocides, Corrosion & Scale Inhibitors, Demulsifiers, Surfactants, Polymers, Gellants & Viscosifiers, Other Chemicals), by Application (Drilling Fluids, Cementing, Enhanced Oil Recovery, Production Chemicals, Well Stimulation, Workover & Completion) and Regional Forecasts 2018-2025