Harold Becker, BJ Unichem Chemical Services
Waxes accumulate as obstructions to the normal flow of crude oil systems. They do this by attracting molecules of like character (e.g., normal paraffin hydrocarbons) and combining through intermolecular forces to form aggregates of a crystalline nature. The aggregates thus formed interact mechanically and accumulate in constricted flow regions, pipe surfaces, and quiescent storage areas. Once it has been determined that paraffin wax accumulation has restricted the normal production, transport, and/or storage of crude oil, measures should be quickly undertaken to remedy the problem. Several remediation methods are available including, hot oiling, hot watering, combination hot water and surfactants, solvent, solvent/surfactant treatments, magnets, bacterial treatments, and crystal modifiers etc.. . Each method possesses strengths and weaknesses. Hot oiling and hot watering are known to be useful in helping to dislodge pumps that are bound up by wax, but their continued practice has also been shown to concentrate higher melting wax fractions in existing deposits thereby making the remaining deposit more difficult to melt in subsequent treatments. Solvent and solvent/ surfactant treatments are excellent means of wax deposit removal, but the extent of their wax carrying ability is limited by temperatures below the cloud point of wadsolvent combination. Crystal modifiers provide the most effective means of preventing deposits, and will in combination with solvents, or hot oil provide significant deposit removal, but they tend to be costly. The successful treatment of paraffin wax accumulations is largely dependent upon the proper identification and characterization of their chemical composition and their physical behavior under various environmental conditions.