Demulsification and rheological characterization of light Malaysian crude oil emulsions using electrocoagulation process / Tajnor Suriya Taju Ariffin

To date, most of the world’s ongoing demand for crude has focused on lighter grades.
However, creation of oil emulsion due to mechanical strength and natural surfactant
during production are undesirable. The challenges associated with transportation and
refining posed by world’s oil produces lead the researchers to probe into practical
demulsification methods. A great understanding of crude oil rheology and operating
condition to treat emulsion is necessary. The research deals with water-in-oil (W/O)
emulsion with API gravity of 38.98. The objectives of this research are to study the
rheological behaviour and demulsification rate of emulsion. The rheological behaviour
of crude oil emulsion has been studied by manipulating the temperature, shear rate and
water volume fraction. The rheological study was conducted within a range of
temperature (30 – 90°C), shear rates (0.1 – 100 s-1) and volume water fraction (20%,
30% and 40%). For emulsion with different water content, the rheological studies
follow non-Newtonian shear thinning behaviour and were described in better way by
Herschel – Bulky model. Besides that, experimental results indicated that measured
viscosity of emulsion decreases significantly with temperature (dropped from 41.0 cP
to 27.9 cP) while increasing water volume fraction resulted in increase in viscosity
(raised from 6.14 cP to 103 cP). The increasing of temperature cause the molecules
loss the chance to agglomerate and thereby breaking the ordered structure thus reduce
the viscosity. Meanwhile, higher water fraction of emulsion characterizes higher
elastic behaviour, subsequently increase resistance to flow then resulted in higher
viscosity. The demulsification rates of water in crude oil emulsion in direct current
fields were investigated under various conditions by using electrochemical cell. The
separation rate of water increased along with the applied field, water content and salt
concentration. The results showed that emulsion separation was governed by the
applied electric field, which yield high separation efficiency up to 85.75% at 30V.
Moreover, as the salt concentration reached 40000 ppm, the separation percentage
achieved 88.75% with shorter time by using copper as electrode. On the other hand,
the highest separation achieved by using aluminium was 62.5%. Copper showed a
better performance than aluminium. This is because, copper is good electricity
conductor, thus it can produced more ions during electrolysis and enhanced the
separation efficiency. The findings obtained from this study proved that the
demulsification process of crude oil emulsion under electric field can have a high
efficiency of separation when the water-in-oil emulsions have high water volume
fraction (40%) and salt concentration (40 000ppm) by using copper electrode with
30V applied voltage.