Evaluation of Propane-Butane Mixtures as Solvent in ES-SAGD
Date
2022-03
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Abstract
SAGD (Steam Assisted Gravity Drainage) is a thermal recovery process for production of nearly immobile bitumen from the deeper oil-sand formation. In this method, two parallel horizontal wells are drilled near the reservoir bottom, one about 5 m higher than the other. Steam injected through the upper well provides heat to the heavy oil to reduce its viscosity. The heated oil flows down into the production well and the space vacated by the oil gets filled with steam, forming a steam saturated zone called a steam chamber. With continued steam injection and oil production, the steam chamber expands vertically and laterally. The SAGD process involves high capital and operating costs, and it suffers from environmental issues. One option being evaluated for improving the energy efficiency of SAGD is the co-injection of a hydrocarbon solvent with steam. In Solvent Added SAGD (SA-SAGD), a small volume fraction of steam is replaced with a hydrocarbon solvent. The latent heat of steam heats the oil while the solvent dissolves in the oil to make it more mobile. The combined impact of mass transfer and heat transfer makes the production rate higher than what can be achieved with only heating. Currently, the least expensive available solvent is propane, but it is not as effective as heavier solvents. So, mixtures of propane and butane are evaluated in the study to see if we can find a solvent mixture for SA-SAGD that can nearly match the performance of pure butane, but at a lower cost. SA-SAGD experiments using different mixtures of propane and butane were conducted in a linear sand-pack to determine the extent of improvement over the base case of steam only (SAGD). The results are used to determine the most effective composition of the propane-butane mixture for SA-SAGD application.
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Keywords
Expanding Solvent- Steam Assisted Gravity Drainage, Petroleum Engineering, Steam Assisted Gravity Drainage
Citation
Ul Abidin, Z. (2022). Evaluation of propane-butane mixtures as solvent in ES-SAGD (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.