Gravity assisted displacement method and application thereof

The invention relates to the field of oil exploitation, in particular to an exploitation method of heavy oil and/or oil sand. The method includes the steps of 1, injecting steam into an injection well; 2, after a steam chamber is stably formed and the oil reservoir pressure is uniformly distributed, adding surfactants into the injected steam and recovering the oil simultaneously; 3, according to the monitored decrease degree of the real-time oil recovery, selecting whether to stop injecting the steam with the surfactants in the step 2, injecting asphalt solvents containing the surfactants into the injection well and recovering the oil simultaneously; 4, after the oil recovery rises to a required level again, stopping injecting the asphalt solvents containing the surfactants in the step 3, injecting asphalt undissolving agents containing the surfactants into the injection well and recovering the oil simultaneously; and 5, according to the monitored decrease degree of the real-time oil reservoir temperature, se