An Environment-Friendly Biomass Nanomaterial for CO2 Enhanced Oil Recovery and Carbon Storage in Low-Permeability Oil Reservoirs

Summary Offshore low-permeability reservoirs have huge reserves and low exploitation levels and have great potential for improving oil recovery. Conventional CO2 flooding is inefficient for enhancing oil recovery, and a large amount of CO2 is produced. This work selects an environment-friendly biomass nano molecule to be an additive for CO2 flooding and studies its influence on the interface behavior, and the potential for enhancing oil recovery and carbon storage ratio. This work selected a biomass active molecule called ARGS-1 to be an additive for CO2-EOR. Pendant drop technique is used to measure the IFT of CO2-water system to reveal the influence of ARGS-1 on IFT. The change in the contact angle of the ARGS-1 solution on the oleophilic sandstone pore wall was measured to reveal the influence of ARGS-1 on the wettability alteration. The oil recovery and carbon storage ratio of conventional CO2 flooding and ARGS-1-assisted CO2 flooding were compared to evaluate the potential of ARGS-1 to enhance recovery and carbon storage. The results indicate that ARGS-1 reduces the IFT of CO2-water from 72 mN/m to 57 mN/m, a decrease of 20%. ARGS-1 has a significant benefit on CO2 breaking through the water film in the pores and contact and recover the remaining oil in the pores. ARGS-1 can reduce the contact angle of the sandstone surface from 91.8° to 67.2° and change the pore wall from a neutral wetting to a water-wet, which is conducive to CO2 stripping the remaining crude oil in the pores. When water altering gas flooding (WAG) can no longer produce oil, adding ARGS-1 to CO2 flooding could increase the recovery of crude oil by 7.1% to 12.5% while increasing the CO2 storage efficiency by 16%-42%. In conclusion, nano agent of ARGS-1 increases the solubility of CO2 by promoting the mass transfer in the water, thereby increasing the CO2 dissolution and storage capacity in the core. The biomass nano molecule is firstly used to improve the recovery and CO2 geological storage efficiency in low permeability reservoirs. ARGS-1 not only significantly improved the recovery, but also greatly increased the carbon storage ratio. It provides an efficient and environmentally friendly chemical means for improving the recovery rate and carbon storage in low permeability reservoirs.