The transportation of waxy crude oil is severely challenged by its high viscosity and tendency to form a gel structure at low temperatures. This study comparatively investigated the effectiveness of microwave treatment versus conventional direct heating in improving the rheological properties of a representative waxy crude oil. The physicochemical alterations were characterized using differential scanning calorimetry (DSC), rotational rheometer, Fourier Transform Infrared Spectroscopy (FTIR), and SARA (saturates, aromatics, resins, asphaltenes) analysis. Experimental results demonstrated the marked superiority of microwave treatment, which reduced the crude oil's viscosity by approximately 80%, lowered the pour point by 12 ℃, and increased the critical wax content for gelation from 3.59% to 6.60%. Furthermore, the yield stress and yield strain of the gelled oil were significantly reduced by 82.45% and 20.05%, respectively. Viscoelastic tests revealed a sustained viscosity reduction effect from microwave treatment, maintaining a 70% reduction rate after 10 days of aging, whereas the viscosity of directly heated samples reverted to their original level within 3 days. FTIR and SARA analyses indicated that the microwave's efficacy stems from its “non-thermal” effect, which facilitates the breakdown of large molecular aggregates, thereby reducing molecular weight and viscosity. In conclusion, microwave treatment fundamentally and persistently enhances the flowability of waxy crude oil, showing great potential for optimizing pipeline transportation.

The pyrolysis behaviors of Qingdao vacuum residue (QD-VR) and its SARA (saturates, aromatics, reins, and asphaltenes) fractions were evaluated by thermo-gravimetric with mass spectrometer (TG-MS). The pyrolysis kinetics were determined by Friedman, one-parallel and four-parallel distributed activation energy model (DAEM), respectively. The results indicated that the pyrolysis behavior of QD-VR was similar to that of aromatics. For saturates, the release of H₂, CH₄, CO, and CO₂ occurred in 80–400 ℃, while the temperature range for QD-VR and other fractions is 200–800 ℃. The average activation energy (E_a) via Friedman method was 179.72 kJ/mol and increased with the conversion ratio. One-parallel Gaussian DAEM was more suitable to describe the pyrolysis process of the single SARA fractions, while four-parallel Gaussian DAEM was more suitable to describe the pyrolysis process of heavy oil. Furthermore, comparing the weighted E_a from one-parallel (227.64 kJ/mol) and four-parallel Gaussian DAEM (204.63 kJ/mol), the results suggested that during pyrolysis process of heavy oil, there was an interaction between the SARA fractions, which could reduce the E_a of heavy oil pyrolysis. Specifically, during heavy oil pyrolysis, resins and asphaltenes could increase the E_a of saturates and aromatics, while saturates and aromatics could decrease the E_a of resins and asphaltenes.