For accelerating asphaltene evaluation, a commercial packaged apparatus applying laser light scattering technique was installed in our laboratory in 2010. This apparatus can measure asphaltene onset pressure (AOP), count/size of precipitated asphaltene particles and density/viscosity. During isothermal de-pressurizing test, AOP is detected by mainly using solid detection system (SDS) equipped in the apparatus. The SDS consists of laser light source, receiver, and glass cell. Measuring by SDS provides continuous profile for power of transmitted light (PTL) that can typically show a sudden drop when asphaltene particles start precipitating. However, our laboratory experience is sometimes faced to untypical PTL profiles. This paper focused on a case that did not detect SDS-basis AOP for a single phased fluid from domestic oil field. To find a way for solution, it was applied to estimate AOP by comprehensively interpreting whole measured data (i.e. particle count/size, density and viscosity) that were simultaneously taken at the SDS application. As a result, appropriate and practical AOP was estimated successfully.
