Abstract: A zone of increased heat and enhanced fluid mobility is established between an injection well and a production well vertically traversing a heavy oil (bitumen, tar) reservoir by (a) first horizontally hydraulically fracturing between the wells, and (b) then injecting hot water and/or steam into the injection well at a very high rate, at a sufficient pressure, and for a sufficient time (holding sufficient back pressure on the production well if needed) to float the formation along the fracture system between the wells, to effect channel flow of fluids through the floated fracture system (with production from the production well), and to effect effective and uniform heating of substantial reservoir volume perpendicular to the channel flow. Thereupon, other thermal methods such as matrix flow steam flooding can be employed to recover additional oil.