Use of organic solvents in sub-sea flow lines, especially in deep water, has never been especially efficient. The generation of paraffin crystals is caused by the reduction of temperature of crystals with the lightest temperatures at which the solid phase in the oil is first initiated. When you have oil submitted to a previous thermal treatment at a controlled cooling rate you are going to have paraffin problems. The best way to prevent paraffin problems is by injecting PRA© on a continuous daily basis. This will avoid the use of expensive mechanical methods such as pigs, scrapers, knives, hot oil, and the use of organic solvents. Removing paraffin deposits by circulating cold organic chemicals sometimes means having to replace costly flowlines to return acceptable production.
