A Study to Improve Versatility and Usefulness in The New Evaluation Method of Asphaltene Onset Pressure （AOP） based on Isothermal De-pressurizing Test Data:

Abstract

The recent asphaltene onset pressure （AOP） detecting method has widely applied Laser-light Scattering Technique （LST） that shows a sudden drop of laser-light transparent due to disturbance by asphaltene precipitated solid particles during isothermal depressurizing test. However, the dependence on one measuring source for deciding AOP might be vulnerable for robust analysis. To improve the reliability of AOP detection, therefore a comprehensive method was established for the interpretation of AOP through simultaneous measuring experiments using synthetic live oil in a certain oil field. For this method, AOPs were simultaneously measured for identical subsamples with various technologies: laser-light scattering, high pressure microscopic observation of asphaltene particle count and size, and viscosity in the previous report by Miyagawa et al.（ 2016）. This method can provide significant advantage such as decrease of experimental error, maximizing effective utilization of costly collected live oil samples, and back up for mistakes in other measuring methods. However, the previous oil samples to be tested were collected from the unique source of domestic oil ?eld. Therefore, the established interpreting method was concerned to fluid-characteristicsdepended with low multiplicity of use. This paper demonstrated that the established method could work with versatility using different source oil sample. Furthermore, for more expanded application such as CO2 EOR investigation, the method was used for CO2-Oil mixtures and successfully interpreted AOP. Consequently, the interpretation approach was revealed to have universal adaptability.