Christine Noik (Institut Francais du Petrole IFP) | Christine S.H. Dalmazzone (Institut Francais du Petrole IFP) | Philippe Glenat (TOTAL S.A.)
For Mobile Extra Heavy Oils (Cold production) and for Bitumen Extra Heavy Oils (Thermal production), dehydration process is based on solvent mixture with additives injection in order to break the Water in Oil emulsions. Dehydration requires injection of large amount of additives, relatively high operating temperature, solvent addition and long retention times inside the vessels.
This process could be improved by electrocoalescence in order to reduce the amount of additive and possibly reduce the vessels retention times to finally reach the oil export specification. However, current commercial electrocoalescence processes have a low efficiency for Extra Heavy Oils because of the presence of polar heavy components limiting the electrocalescence effect and consequently limiting the efficiency of electrostatic coalescer.
The objective is to determine the most efficient electrocoalescence parameters considering the characteristics of two types of heavy crude oils issued from Cold and Thermal productions: the aim is to optimize the development of a pre-electrocoalescer unit adapted to the extra-heavy oil characteristics. This paper presents experimental results for electrocoalescence additive selection and for the optimization of electrical parameters.
The crude oils behaviour was analyzed considering their tendency to form an emulsion under controlled hydrodynamic conditions in relation with the oil/water interface dynamics. For the electrostatic dehydration, the optimization of the emulsion breaker concentration was performed using the Electrical Stability Tester API device. The minimum concentration that triggers electrical short-circuiting in relation with droplet coalescence was selected. The electrical parameters of the preelectrocoalescer
device were determined in presence of the selected additive concentration. For the two types of crude oils, high voltage and high frequency up to 1 kHz are required in combination with the addition of solvent and additive in order to destabilize the water in oil emulsions. Correlation between dehydration efficiency and residence time under electrical stress is established.