Highly thermoconductive biogel for enhancing thermal efficiency and soil self-remediation in heavy oil recovery

The thermal recovery of heavy oil is an energy-intensive process with serious soil contamination due to its low energy efficiency and refractory petrolic/metallic pollutants emissions. In this work, a thermoconductive lignin-based hydrogel CaLS-CTS/h-BN was designed and synthesized for thermal energy conservation and soil self-remediation in thermal recovery, as a profile-control and oil-displacement agent. From experimental results, with the assistance of CaLS-CTS/h-BN gel, the thermal efficiency and cumulative oil-steam ratio of steam flooding were enlarged by 260% and 293% (up to 41.3% and 0.36), as input energy declined (reduction ratio 84.8%) from 15.08 kJ.(mL oil)(-1) to 2.29 kJ.(mL oil)(-1), through improving heating profile and strengthening heat transfer. Meanwhile, the rapid biodegradation of CaLS-CTS/h-BN biogel alleviated the formation damage and preserved subsequent productivity. On the other hand, after application of CaLS-CTS/h-BN gel, the natural degradation ratio of petroleum pollutants in soil was increased by 254% up to 46% due to the bio-stimulation and bio-ventilation effect of the biogel. Heavy metal content of oilfield soil was reduced by 35.8 wt% (from 17.3 g.(kg soil)(-1) to 10.9 g.(kg soil)(-1)) with multiple heavy metal contaminants (including Cd, Cr, Cu, Zn, Mn, Pb and Fe) chelated and immobilized by the biogel. This study offered a green adjuvant agent for cleaner production of heavy oil.

Automated summary

In this study, a thermoconductive lignin-based hydrogel CaLS-CTS/h-BN was designed and synthesized for thermal energy conservation and soil self-remediation in thermal recovery of heavy oil. The gel improved the thermal efficiency and cumulative oil-steam ratio of steam flooding, reduced input energy, and enhanced heating profile and heat transfer. It also facilitated the biodegradation of the gel, alleviated formation damage, and increased the degradation of petroleum pollutants in soil. Additionally, it chelated and immobilized heavy metal contaminants in oilfield soil. This study provided a green adjuvant agent for cleaner production of heavy oil.