Enhanced Deoiling Hydrocyclone Performance without Resorting to Chemicals

Abstract There are many produced water deoiling hydrocyclone systems operating today that do not meet the required overboard discharge water quality specification. Common reasons for this include long term changes in field conditions, adverse interfacial chemistry (generally caused by a "cocktail" of chemical additives), small inlet dropsizes or sub optimal deoiling hydrocyclone liner types (e.g. large diameter geometries). The most common solution to these PWT problems is to implement a chemical injection programme which although can be successful, has a high operating expenditure requirement and can often be more harmful to the environment than the oil it was designed to remove. There is also a general industry initiative to minimise the use of production chemicals in a response to the belief that new legislation governing toxic chemical and dissolved hydrocarbon discharge is imminent. This paper describes a technology which has been developed by Cyclotech to significantly improve the performance of produced water deoiling hydrocyclone systems without resorting to chemicals. The concept is based on precoalescing the inlet oil dispersion to produce a coarser drop size distribution prior to hydrocyclone entry. Field trials have demonstrated that the technology can improve the deoiling performance by as much as 220%. It requires no external control or power source; displays a marked insensitivity to solids fouling and can be easily retrofitted into existing systems without the need for any major vessel or pipework modifications. The technology is aimed at existing systems which do not meet discharge specification, or require excessive chemical dosing to do so and at new-build systems by extending the applicability of hydrocyclone based solutions to heavy oil, condensate and other historically marginal applications.