Chasing solvent for enhanced recovery processes

A method for recovering hydrocarbons from an underground reservoir, the method comprising:

• (a) injecting a solvent into the reservoir at a pressure above a liquid/vapor phase change pressure of the solvent;
• (b) injecting a chaser into the reservoir at a pressure above the liquid/vapor phase change pressure of the solvent;
• (c) allowing the solvent to mix with the hydrocarbons and at least partially dissolve into the hydrocarbons to produce a solvent/hydrocarbon mixture;
• (d) reducing the pressure in the reservoir below the liquid/vapor phase change pressure of the solvent thereby flowing at last a fraction of the solvent/hydrocarbon mixture from the reservoir;
• and
• (e) repeating steps (a) to (d), wherein the composition of the solvent in the repeated steps (a)-(d) is a first solvent composition which is the same as the composition of the solvent in the initial steps (a)-(d), or the composition of the solvent in the repeated steps (a)-(d) is a second solvent further comprising a diluent and has a different composition than the solvent in the initial steps (a)-(d);
• wherein the entire injection of the solvent and chaser in steps (a) and (b) and the entire production of the solvent/hydrocarbon mixture in step (d) are through a common wellbore;
• and
• wherein the volume of chaser in step (b) is between 1% and 10% of the total injected fluid by volume of the combined solvent and chaser, and the volume of the chaser as a percentage of the total injected fluid by volume of the combined solvent and chaser is increased in multiple repeated cycles of step (e) to a maximum of 80% of the total injected fluid by volume.