Dimethyl Ether as a Solvent for In-situ Heavy oil and Bitumen Recovery
Date
2023-06-02
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Abstract
As part of its Healthy Environment and Healthy Economy (HEHE) plan to address climate change, the Canadian government intends to increase the carbon tax from its current level of $30 per tonne to $170 per tonne over the next nine years. To respond to this plan positively, oil companies have started to address the most significant issue on carbon emissions from their current oil recovery processes, such as steam assisted gravity drainage (SAGD), by utilizing more environmentally responsive processes. Pure or hybrid solvent injection was proposed as an alternative method; however, its previous studies were limited to a conventional solvent (n- alkane), which is not economically feasible. Dimethyl ether (DME), an emerging renewable chemical resource, was initially proposed as a solution to reduce carbon emissions and aroused interest in the heavy oil industry. But limited research has been carried out for understanding and evaluating DME`s performance in heavy oil recovery. In this thesis, essential mechanisms including phase behavior, asphaltene deposition, reservoir responses due to solvent injection or solid adsorption, and mass transfer by considering water phase solubility during DME injection have been studied by numerical simulation. In detail, a) concentration-dependent binary interaction coefficients have been proposed to represent an asymmetric phase system; b) a general analytical model for predicting a heavy oil gravity drainage rate has been proposed; c) reservoir responses due to solvent injection andasphaltene depositionhave been investigated; d) a workflow of a semi- compositional approach has been proposed to accurately predict asphaltene precipitation behavior and then an innovative numerical model has been built for investigating asphaltene precipitation and in-situ upgrading in DME-VAPEX (vapour extraction). To conclude, DME has been evaluated as a promising solvent for heavy oil and bitumen recovery with a less negative blockage effect, a higher recovery factor and rate, higher API upgrading, and higher energy efficiency compared with a conventional solvent. DME, as a renewable, amphoteric chemical solvent, will lead to significant implications in addressing the challenges brought by carbon emissions.
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Keywords
Dimethyl ether, Bitumen, Heavy oil recovery, Asphaltene deposition
Citation
Chai, M. (2023). Dimethyl ether as a solvent for in-situ heavy oil and bitumen recovery (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.