Through the combination of imbibition and displacement,the impact of the combined action of imbibition and displacement on reservoir pressure and fluid flow during the soaking process after reverse hydraulic fracturing assisted oil displacement in low-permeability reservoirs was explored.A semi-analytical mathematical model for productivity prediction of reverse hydraulic fracturing assisted oil displacement is established,considering interlayer heterogeneity.An analysis was conducted on the changes in the flow field before and after soaking.Parametric studies are conducted to reveal the effects of permeability ratio, total injection volume,injection rate and soaking time on the pressure swept range,saturation swept range and cumulative oil production of each layer after soaking.The research results indicate that soaking well after hydraulic fracturing assisted oil displacement can enhance the energy enhancement effect of reverse hydraulic fracturing assisted oil displacement,further expand the affected area,and thus utilize more geological reserves.To achieve efficient development through hydraulic fracturing assisted oil displacement,it is recommended to consider layered mining when the permeability ratio is greater than 25.Meanwhile,the soaking time should be controlled within 10~15 days,with a properly reduced injection rate and increased total injection volume.