Rheological and Thermal Behavior of Water-Waxy Crude Oil Emulsions and Model Oil Systems

The prediction of yield stress for waxy crude oil emulsions and the understanding of oil gelification process play a major role in flow assurance. Oil characterization and its wax content can also provide useful data, specially for engineers engaged in production procedures at offshore drilling plataforms. Since petroleum is a complex mixture of many chemical compounds, a systematic study involving model oil is suitable to account for specific influences on yield stress of systems under gelling conditions. The present work aims to study the behavior of systems at gelation conditions. Therefore, waxy crude oil emulsions and model oil systems were investigated. Rheological and thermal analysis were employed for yield stress measurments and estimations of wax amount precipitated, respectively. Characterizations by DSC, C¹³RMN, SARA and GC-FID were also carried out. It was verified that cooling was the most import step on yield stress appearance whilst shear rate had the biggest impact on gelification for both systems. The chemical nature of parrafins employed (branched or linear) also played an important role on yield stress values. From the results, it could be shown that aging times larger than 15 minutes did not affect yield stress appreciably.