Conduction and Dielectric Relaxation Mechanisms in Athabasca Oil Sands with Application to Electrical Heating

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• 作者：Tinu Abraham ; Artin Afacan ; Priyesh Dhandharia ; Thomas Thundat
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：July 21, 2016
• 年：2016
• 卷：30
• 期：7
• 页码：5630-5642
• 全文大小：849K
• 年卷期：0
• ISSN：1520-5029

文摘

Six oil sands with increasing water and clay content were investigated for their electrical relaxation mechanisms using broadband dielectric spectroscopy with frequency (1 Hz to 1 MHz) and temperature (20–200 °C) to identify suitable operational strategies for electrical heating. Oil sands having least water and clay content showed a conduction relaxation mechanism following Jonscher’s law due to Maxwell–Wagner (MW) polarizations at bound water interfaces between bitumen and silica grains. MW polarizations due to free water interfaces between 1 kHz and 1 MHz were observed for oil sands having pendular connected water channels between sand grains. Poor oil sands with water entrapped in fine clusters had a dominant dc conduction mechanism. Additionally, all oil sands displayed dipole relaxations due to bitumen molecules between 100 kHz and 1 MHz. Electrical properties increased as temperatures were increased from 20 to 120 °C, whereas a further increase from 120 to 200 °C resulted in reduction of these properties and dominance of ac conduction, causing all oil sands to behave the same irrespective of their grade.