Qualitative analysis and quantitative evaluation on the stimulation mechanisms of hot water flooding in tight oil reservoirs

To enhance the recovery factor of tight oil reservoirs, the target block was selected. Then, based on the core and crude oil data collected in the feld, the stimulation mechanisms of hot water fooding considering variable threshold pressure were investigated by means of laboratory experiment. And fnally, all stimulation mechanisms of hot water fooding were quantitatively evaluated by using the numerical simulation method. The laboratory experiment results show that thermal expansion, threshold pressure decline, thermal viscosity reduction, interfacial tension decrease and relative permeability curve improvement are the oil displacement mechanisms of hot water fooding in tight oil reservoirs, and thermal expansion and threshold pressure decline are the main stimulation mechanisms. Numerical simulation results indicate that the contribution ratios of thermal expansion and threshold pressure decline are the highest when hot water fooding is carried out at 100 ℃ and 150 ℃. The contribution ratio of thermal expansion is 29.79% and 33.28%, respectively, and that of threshold pressure decline is 31.66% and 30.48%, respectively. Relative permeability improvement and thermal viscosity reduction take the second place, and the contribution ratio of interfacial tension decrease is the lowest (7.08% and 6.27%, respectively).Obviously, the correctness of experimental results is verifed further by the simulation results.