Evaluation And Improvement Of Test Methods For Colloid Stability Of Crude Oils

Crude oil mixture on the one hand is the need of storage, transportation or production and processing, on the anther hand may greatly reduce the cost of crude oil which brings economic benefits. When mixed, the incompatibility of crude oil may leads to unstable asphaltene flocculation or deposition. Asphaltene deposition, scaling and coke in the process of production, transportation and processing will seriously affect the efficiency of pipelines or equipments, what’s more, will block pipelines and equipments. These problems caused huge economic loss to the refinery. Therefore, the compatibility of blending system has becoming one of research focuses in the field and has attracting the attention of the researchers at home and abroad.In this topic, Manas oil is evaluation objects, Filter Drop Spreading method(FDS method), interfacial tensiometry, Mass fractionconductivity method(MFNC method),spectrophotometric method(SPM), laser particle size analysis(LSPSA), Parameter P and SBN/IN Model, was used to obtain the asphaltenes precipitation onset(PO), combining with the experimental conditions. It turned out that analysis results of FDS method, MFNC method, SPM, Parameter P and SBN/IN Model is mainly consistent with each other and come to a conclusion that the Manas oil is stable; In order to search the compatibility rule of mixed crude oil, this experiment researched the Manas oil as the main object, two kinds of Tarim Basin oils and FCCSO as mixed oil, adopting MFNC and SPM method to obtain PO of oil mixture, and improved MFNC method, introducing compatibility critical line to predict the compatibility of oils mixture. Three prediction methods, SBN/IN Model, Parameter P and Y intercept, can directly be used to determine the compatibility of in the process of crude oil mixing. It turned out that compatibility critical line to predict the compatibility of oils mixture.After adding the three kinds of mixed oils to well stable Manas oil, PO value of the blending system is lower than PO value of the Manas oil itself; But the results of the stability/compatibility of the oil mixture judging by the size of PO value are not ideal; Prediction results of compatibility critical line, Y intercept, SBN/IN Model and Parameter P are in the agreement. When unstable FCCSO blended with well stable Manas, PO values are reduced along with the increase of the mixing ratio, and when the mixing ratio is 40%, the oil mixtures is incompatibility while the other mixing system are compatibility, the order of stability of mixing systems as follows:0%(Manas oil)>60%>80%>20%>0>40%>100%(FCCSO)(percentage on behalf of the mixed oil-FSSCO etc. mass ratio of oil mixture, greater than zero on behalf of incompatible). Tarim Basin 2 don’t contain asphaltene is a system with excellent stability, but when it blend with Manas oil, it will easily occur incompatible phenomenon, and the PO value increased gradually, the order of stability as follows:100%(TBC2)>0%(MNC)>0>60%>40%>20%>80%. Blending of two kinds of stable oil may also occur incompatibility phenomenon, Tarim Basin 3 blended with Manas oil are incompatible, order of stability/compatibility of blend system as follows:0%>0>20%>80%>40%>60%.