A controllable chemical reaction assisted SAGD for enhancing oil recovery and reducing CO2 emission in heavy oil reservoirs

•The controllable chemical reaction-assisted SAGD technology enables low-carbon and efficient development of heavy oil.•The controllable chemical reaction replaces boiler heating to reduce CO2 emissions.•Non-condensable gas, solvent gas, and reaction heat synergistically enhance SAGD development.•Modeling of the controllable chemical reaction-heavy oil thermal recovery is established. SAGD (Steam-Assisted Gravity Drainage) development of heavy oil requires diesel heating through steam boilers, leading to energy consumption and CO2 emissions. To address this issue, we propose a Fischer-Tropsch (F-T) reaction assisted SAGD technology for heavy oil recovery. By conducting F-T reaction experiments to establish chemical reaction equations, it is demonstrated that altering the CO and H2 ratios enables controllable initiation of the F-T reaction. Subsequent utilization of reservoir numerical simulations facilitates the analysis of the mechanisms underlying the enhanced efficiency of heavy oil development through chemical reaction products and heat release. Evaluation indicators for emission reduction are established during the process, and the impact of the reactions on emission reduction is discussed. Various application scenarios of the controllable chemical reaction technology to assist SAGD development are presented and demonstrating its economic feasibility. Results indicate that the steam quality of 450 m3/d injection rate reaches 0.95, and with 6.93 % of the heat supplied by chemical reactions, a single well reduces diesel heating by 1.01 × 1010 kJ/year. Compared to SAGD, this technology leads to a reduction of 4.64 × 105 kg/year per well in CO2 emissions and a 7.7 % increase in recovery rate.