Laboratory Investigation of Diluted Bitumen Trapping and Dissolution in Gravel
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Authors
Hossain, Sheikh Zubair
Date
2016-08-26
Type
thesis
Language
eng
Keyword
Gravel-bedded Rivers , Capillary Pressure-Saturation Relationships , Dilbit , Interphase Mass Transfer , Diluted Bitumen
Alternative Title
Abstract
The Canadian economy is largely dependent on the distribution of large volumes of oil to domestic and
international markets by a long network of pipelines. Unfortunately, accidents occur, and oil can leak or
spill from these pipelines before it reaches its destination. Of particular concern are the long-term
consequences of oil spills in freshwater, which include sinking of oil in water and the contamination of
sensitive areas, such as where fish (e.g., salmon) deposit their eggs in gravel-dominated river sediments.
There is a knowledge gap regarding the fate and behaviour of oil in river sediment.
To this end, this study aimed at finding the potential for diluted bitumen (dilbit) oil to become trapped in
gravel and to transfer hydrocarbons into water by dissolution, which are harmful to aquatic life. Two sets
of laboratory experiments were conducted to simulate conditions of an oil spill on an exposed bank or in
shallow water. In the first set, by conducting capillary pressure-saturation (Pc-Sw) experiments it was found
that dilbit can enter gravel pores without much resistance and approximately 14% of the pore volume can
be occupied by discontinuous single or multipore blobs of dilbit following imbibition of water. Air-water
Pc-Sw experiments done in laboratory 1-D columns required gravity correction and could be successfully
scaled to predict dilbit-water Pc-Sw curves, except for the trapped amount of dilbit.
Trapped dilbit constituents can be dissolved into the water flowing through gravel pores (hyporheic flow)
at different velocities. In the second set, dissolution experiments suggested that for the duration of the test,
hydrocarbons that cause acute toxicity dissolve rapidly, likely resulting in a decrease in their effective
solubility. However, dilbit saturation changed only <2% within that time. Chronically toxic PAH
compounds were also detected in the effluent water. The total concentration of all detected PAHs and alkylPAHs exceeded the threshold literature value to protect early-life stage fish. Observations of decreased
concentrations with increased aqueous velocities as well as less than equilibrium concentrations indicated
that the mass transfer was rate-limited. A correlation was developed for the mass transfer rate coefficient
to understand the mass transfer behaviour beyond the conditions used in the experiments, which had a
Reynolds number exponent similar to the studies of NAPL dissolution in groundwater.
Description
Thesis (Master, Civil Engineering) -- Queen's University, 2016-08-26 08:55:08.21
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.