Polymeric nanoemulsions facilitate flow and reduce drag and friction in multiphase pipelines containing both oil and water (e.g., oil/water, oil/water/gas, oil/water/solids, and oil/water/gas/solids) such as are used for oil or gas production, gathering, and transmission; hydrotransport of oilsand or heavy oil slurries and the like. Specific examples of suitable drag reducing polymers include polyacrylamide. The emulsions have a hydrocarbon external phase, droplets of an aqueous internal phase having water-soluble polymer dissolved therein, where the droplets have an average particle size below about 200 nm, and at least one surfactant to form a stable nanoemulsion. The nanoemulsions advantageously have a low viscosity of about 200 cP or less.