Simple Techniques for Evaluation of Crude Oil Compatibility

Blending crude oils or crude oils and condensates of different origin may give rise to deposit related problems due to incompatibility. Although the problem has been recognized, there are as yet no standard methods for the determination and quantification of crude oil compatibility. This study focused on the compatibility of stock tank oils in storage depots and refineries. Using blends of Arabian Medium and Gippsland crude oils as a model system, various simple techniques were investigated and compared with the results of the in-house Shell stability test (the Po/FRmax test): microscopy, a modified Hot Filtration Test, a modified ASTM spot test and a modified Shell Spot test. All techniques (with the exception of the ASTM spot test) were capable of identifying an unstable regime, but the onset of asphaltenes flocculation varied with the experimental conditions. Sample pretreatment was found to be a necessary prerequisite for obtaining meaningful data. The Shell Spot Test appears to be a fast and simple method for monitoring crude oil compatibility in the downstream business.