Polymeric naphthenate inhibitors are delivered into production fluids to contact mixtures of oil and water, such as in a hydrocarbon producing formation, production equipment, or processing systems. These polymeric naphthenate inhibitors exhibit surface-active properties causing the inhibitors to self-associate at oil-water interfaces and inhibit interactions between organic acids in the oil and cations or cation complexes in water. The large surface area makes these polymers persistent and effective at low concentrations. These compounds also inhibit aggregation of organic acid carboxylate salts that form when pH and pressure conditions are amenable to organic acid ionization. Preferred inhibitors do not form emulsions due to the formation of unstable mixed interface structures that result in coalescence of dispersed droplets. Naphthenate inhibitor dosages less than 100 ppm can effectively inhibit naphthenate salts or other organic acid salts that can form precipitates or emulsions during crude oil production or processing.