Phase Behavior and Physical Properties of Athabasca Bitumen and Solvent Mixtures
Date
2023-08-30
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Abstract
Solvent-aided thermal recovery techniques are gaining prominence for extracting bitumen and heavy oils. These methods involve co-injecting saturated steam and solvent into bitumen reservoirs. The phase behaviour of solvent and bitumen is crucial in designing and optimizing any solvent-assisted in-situ bitumen recovery. This study investigates vapor-liquid equilibrium (VLE) between various solvents (including dimethyl ether DME, C1, C2, C3, C4, n- C5, C1/n-C5, C1/n-C6, C1/n-C7, and C1/ C3+n-C4+n-C5) and Athabasca bitumen. Parameters such as equilibrium compositions (K-values), liquid-phase density, and viscosity were measured at temperatures up to 260 °C and pressures up to 6 MPa. Methane's solubility in bitumen showed minor temperature dependence (200, 230, and 260 ºC), while ethane, propane, and n-butane exhibited more significant temperature effects. The study also compared co-injection of DME/steam to traditional steam and steam/butane injections in a 2D sand-pack saturated with Athabasca bitumen. Results indicated DME's efficacy in enhancing bitumen recovery, making DME and steam co-injection promising. Another focus was the impact of solution gas (methane) on K-values in solvent/live bitumen and solvent dead bitumen systems. In the first stage of experiments, K-values, density and viscosity for methane/bitumen, propane/bitumen, and n-pentane/bitumen were measured. In the next step, methane, pentane, and bitumen were mixed at two concentrations (one with high and the other with low GOR live bitumen). Then K-value, density and viscosity of methane/n-hexane/bitumen and methane/n-heptane/bitumen system were measured. In the final stage of experimental data collection, K-values, density and viscosity of methane/propane, n-butane, and n-pentane/bitumen system were measured. The collected experimental PVT data of solvent and bitumen were modeled using PR-EoS, and experimental and calculated k-values of methane, propane, n-butane, n-pentane, n-hexane, and n-heptane data were compared for solvent/live bitumen and solvent dead bitumen system. Also, K-values of methane for methane /solvent(s) /bitumen and methane/bitumen systems were compared to study the effect of methane on the K-values of other hydrocarbon solvents. The results show the variation of methane and n-pentane K-values between various systems are within the experimental error, which means for the modeling and reservoir simulation purposes, we can use the K-values for any of these systems.
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Keywords
Bitumen, Solvent-aided thermal recovery, Dimethyl ether, Phase behaviour, Thermal recovery, Oil sands, Methane
Citation
Haddadnia, A. (2023). Phase behavior and physical properties of Athabasca bitumen and solvent mixtures (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.