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Thermodynamics and Phase Behavior of Hydrocarbon Solvents at Capillary Conditions

  • Author / Creator
    Al Kindi, Ilyas
  • This thesis experimentally investigates the phase-change behavior of hydrocarbons in various categories of the porous system. The experimental journey was initiated by studying the boiling behavior of single-component hydrocarbon liquids (heptane and decane) and water in silica-glass Hele-Shaw cells which is represented as simple capillary spaces with different sizes. The analysis was performed under atmospheric pressure (1 atm). Despite their simplicity, using Hele-Shaw models brought the advantage of clear vapour generation visualizations. Shifted boiling temperatures were observed in the glass cells, due to the confinement effect. The outcomes were then used to modify the Thomson equation by suggesting alternative formulations. As a next step, the vaporization of heptane (as a pure component), heptane-decane mixture (50% mass fraction for each component), and naphtha (as a multicomponent solvent) was analyzed in homogeneous (uniform pore-throat sizes) and heterogeneous (non-uniform pore-throat sizes) silicate-glass microfluidic chips, at atmospheric pressure. Relatively, the heterogeneous micromodels had a closer representation of the rock porous media, compared to the Hele-Shaw cells. Early vaporizations of solvents were clearly observed in the micromodels, as a result of capillary effects in the porous systems. Studying the condensation of propane in various reservoir rocks under isothermal and non-isothermal conditions was also a part of the investigation. Initially, the phase-change pressure of propane was measured in Hele-Shaw cells with various gap sizes, capillary tubes with different sizes (1 – 40 micrometers), and microfluidic chips. The capillary effect in the silica-glass models was not sufficient to alter the propane vapour and condensation pressures and they were identical to the bulk measurements or those computed by the Kelvin equation. However, as observed with the hydrocarbon liquids, vaporization of propane was taking place in sandstone, limestone, and shale at pressures which were approximately 10% lower than the bulk vapour pressure. As a further step, the vaporization of propane was inspected in sandstone, limestone, tight sandstone, and shale at various temperatures, ranging from 0℃ (273.15 K) to 40℃ (313.15 K). The experimental observations were then compared with the bulk vaporization pressures and computed saturation pressures by the Peng-Robinson EoS and Kelvin equation. The recorded vapour pressures, in the rocks, were 7% lower than the bulk values and calculated vapour pressures by the Kelvin equation. Meanwhile, the propane vapour pressures, in the rocks, were 15% (on average) lower than the pressures modelled by the Peng-Robinson EoS. Lastly, phase distribution of pure-component solvent (pentane), binary mixture (pentane-heptane), and trinary mixture (pentane-heptane-octane) was studied by comprehending the dynamical behavior of hydrocarbon phases in heterogeneous and homogeneous porous systems under capillary conditions.

  • Subjects / Keywords
  • Graduation date
    Spring 2021
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/r3-wkm6-p248
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.