Rheological Behavior of Waxy Crude Oils under Oscillatory Shear and Effect of Plant Seed Oil

  IJETT-book-cover  International Journal of Engineering Trends and Technology (IJETT)          
© 2018 by IJETT Journal
Volume-58 Number-4
Year of Publication : 2018
Authors : Adam M Giri, Ali A. Rabah
DOI :  10.14445/22315381/IJETT-V58P231


Adam M Giri, Ali A. Rabah"Rheological Behavior of Waxy Crude Oils under Oscillatory Shear and Effect of Plant Seed Oil", International Journal of Engineering Trends and Technology (IJETT), V58(4),165-176 April 2018. ISSN:2231-5381. www.ijettjournal.org. published by seventh sense research group

Different samples of waxy crude oils were taken before pipeline inlet to field processing facility in the Hadida and Heglig crude pipelines which carrying crude oil from producing oil fields located in the west part of the west Kordofan state, to the costal terminal at Port Sudan. Samples were tested for their flow behavior under superimposed small amplitude oscillatory by dynamic rheometer. The oscillation behavior of the crude oils is measured under dynamic rheological tests for the following parameters: strain sweep, frequency sweep and temperature sweep tests. However, strain sweep was first performed at frequency 10 rad/sec and temperature of 50oC (below wax appearance temperature) to determine linear viscoelastic region. Further, the linear viscoelastic region was calculated as (0.05%) which is used to carry out frequency sweep and temperature sweep tests. . Moreover, untreated and additive treated crudes with flow improvers (Jatropha Curcas seed oil and Xylene) were used to identify the impact of additives on pour point, wax appearance temperature and flow properties of the crudes. GC-FID was introduced to perform a composition analysis for untreated and additive treated crudes and average carbon number distribution was identified as C26. In addition, untreated and additive treated crudes were thermal fractionated and their wax appearance temperatures were measured by DSC and the results compared with those obtained from viscometry method. Further, the two crudes show high pour point (33 oC and 33 oC) and high wax appearance temperature (59.88 oC and 59 oC) for Hadida and Heglig crudes respectively, which is essentially required treatment for their storage, production and transportation via pipeline. Moreover, it was observed that concentration of 5%v/v Jatropha seed oil and xylene capable to reduce Heglig crude pour point from (33 oC to 15 and 18 oC) respectively, on the other hand all pour point depressant used in this study were failed to affect the pour point of Hadida crude, but they affect its viscosity and show improvement in the flow behavior. However, Hadida and Heglig crudes exhibit a negligible amount of asphaltenes content (0.05) and there may be no problems for the crudes rheology with asphaltenes precipitation. Furthermore, measured rheological parameters such as storage modulus (G`) and loss modulus (G") reveals that, the two crudes exhibit viscoelastic behavior where at low frequencies storage modulus dominate loss modulus indicating solid-like behavior and at high frequencies loss modulus dominate storage modulus indicating liquid-like behavior, also gelling behavior of the crudes was determined by crossover point at which the G` value overlap the G" value and this behavior was confirmed by low tan ? values (i.e. less than one as indicated in Table 4). Furthermore, vegetable seed oil obtained from plant sources such as Jatropha Curcas seed oil could be used as flow improvers for pour point depressant and enhances flow properties of Sudanese waxy crude oils.

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Waxy crude oils, Chemical additive, Jatropha seed oils, Rheology, DSC, Thermal and Oscillatory Behavior