The effect of chlorella hydrothermal products on the heavy oil upgrading process

In-situ upgrading can improve the scale of heavy oil development, but the efficiency of in-situ hydrothermal hydrogen supply is limited. In this paper, the combination of algae hydrothermal liquefaction and heavy oil upgrading and viscosity reduction process is proposed. The liquefaction products of hydrothermal liquefaction are used to supply hydrogen to the heavy oil upgrading and viscosity reduction process, thereby enriching the supply path of active hydrogen. The effects of hydrothermal liquefaction temperature of Chlorella and the addition of 5% Fe/HZSM-5 catalyst on the liquefaction rate and product distribution of Chlorella were investigated, and the upgrading and viscosity reduction process of heavy oil with the participation of hydrothermal liquefaction products was discussed. The results show that when the temperature of upgraded heavy oil is 280 °C and 5 wt% of hydrothermal liquefaction products are added and reacted for 24 h can make the viscosity reduction rate of heavy oil reach 84.32%, and 31.2% of resin in heavy oil was converted into aromatic hydrocarbon. Elemental analysis showed that the upgraded heavy oil H/C ratio increased, and GC–MS analysis showed that the distribution of algae hydrothermal liquefaction products could be adjusted by the catalyst, and more aromatics were produced after the addition of the catalyst, which confirmed that the aromatics in hydrothermal liquefaction products had a significant effect on the quality improvement and viscosity reduction of heavy oil. Its molecular weight was also found to be reduced from 853 to 326 in the average molecular weight test (GPC). The efficient carbon sequestration of algae is combined with the demand for carbon dioxide emission reduction in oilfields to realize the recycling of carbon resources.