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.