In Western Canada, many heavy oil reservoirs are underlain by thick bottom water. Very few of these reservoirs are commercially exploitable by conventional cold production or thermal technologies because of the high water mobility. The water zone could act as a strong water source that causes production wells to water-out quickly, or as strong energy sink that takes away most of the injected heat energy. As a result, these reservoirs are generally not attractive to produce, despite the enormous oil resources contained in them. Can the high mobility of water be beneficial to oil recovery? Can the known properties of bottom water (e.g., the oil-water contact, viscosity, density, and thermodynamic properties of water, etc.) be used as process tools to implement a successful recovery process? This paper attempts to address the above issues by introducing a new "Basal Combustion" concept that is built on the energy and mass transport characteristics of bottom water. Numerical simulation results indicated that, with the help of an effective transport and gathering system, a near level combustion surface could be initiated at the bottom of a heavy oil zone. The gas and water flows could serve as underground "conveyor belts" to deliver heat to the cold oil zone and, at the same time, remove mobilized and upgraded oils from the high temperature regions. High recovery and high energy efficiency can be expected.