A Study Of The Relationship Between Interfacial Film And Emulsion Stability

Petroleum is an important resource and good fuel. Many researchers have done a lot of work in enhancing oil exploitation efficiency. Enhanced oil recovery has been regarded as the "National Key Research Development Program", china. Emulsion stability ties up oil exploitation efficiency. Interfacial film is a key factor witch affects emulsion stability. The relation between interfacial film and emulsion stability was investigated in this paper.It is essential to form emulsions the presence of emulsifier, which changes the nature of the interfacial film and further affects emulsion stability. The influence of the components of the enhanced oil recovery system which has been successfully applied to certain oil fields, sodium carbonate, polyoxyethylene (10) alkylphenol ether (OP-10), sodium petroleum sulfonate (CY-01) and hydrolytic polyacrylamide (HPAM) 3530S, on the interfacial film and the emulsion stability was investigated in this paper. The influence of the naturally occurring surfactants in the crude oils, asphaltenes and resins, as well as inorganic salts and solid particles on the interfacial film was also investigated in this paper. A study of emulsion was performed by means of conventional heating and microwave radiation. It was shown that the factors and the means all can change the nature of the interfacial film in some extent. These factors and means are selective ways to change the emulsion stability.This paper presents experimental data proving the influence of the enhanced oil recovery system's components, sodium carbonate, polyoxyethylene (10) alkylphenol ether (OP-10), sodium petroleum sulfonate (CY-01) and hydrolytic polyacrylamide(HPAM) 3530S, on the interfacial film and the emulsion stability. Among which, the effects of surfactants, polyoxyethylene (10) alkylphenol ether (OP-10) and sodium petroleum sulfonate (CY-01) on the emulsion stability are the strongest of any component, the effects of polymer, hydrolytic polyacrylamide (HPAM) 3530S, on emulsion stability are the weakest. The emulsion stability can be controlled by changing the proportion of the enhanced oil recovery system's components. It was found that emulsion stability is related to the concentrations of the asphaltene fraction and resin fraction hi the crude oil, and the state of dispersion of the asphaltene fraction and resin fraction (molecular vs colloidal) was critical to the strength or rigidity of interfacial film and hence to the stability of emulsion. The percentage of coalesced water droplets decreases with the concentration of the asphaltene fraction or resin fraction in the range of 0.3 wt % up to 0. 5 wt % or 1 wt % up to 2 wt %. However, after the concentration of the asphaltene fraction or resin fraction is increased to 0.7 wt % or 3 wt %, the percentage of coalesced water droplets increases with the concentration of the asphaltene fraction or resin fraction, with a subsequent decrease hi the amount of droplets of the emulsion. It was found that a very small amount of inorganic salts can effectively accelerate the demulsification. This effect is due to the destroying of the double charge layers by the inorganic salts. The efficiency of demulsification by using the inorganic salts is related with ionic valency and ionic hydrated radius. For oil-in-water emulsions, maximum demulsification efficiency by adding AlCl2 is up to 100 % with oil-bath heating at 90℃ for 10 min. For water-in-oil emulsions, the demulsification efficiency by using NaCl as a demulsifier is higher than those by using other Cl- salts and Na+ salts. The emulsion volume in the presence of NaCl remains to 0.02 mL with oil-bath heating at 90℃ for 60 min. Some solid particles can effectively resist the demulsification and increase the emulsion stability. Optical microscopy photographs approve that the graphite powder and the barium sulfate can form the formation of this multi-size solid network. The network structure of solids can retarddemulsification by increasing the steric hindrance and by enhancing the strength of the interfac...