Abstract: A process useful in mixing reagents delivered to an injector well which reacts with bitumen-heavy petroleum products in the injector well. The reaction produces significant heat to the bitumen reservoir rock, the heat lowers the viscosity of the material, and permits the flowable material to be collected by a nearby producer well, usually beneath the injector well. The well is assisted with a vacuum system to remove the bitumen containing petroleum materials. This is a method of selectively initiating in situ chemical reaction causing the heating of a targeted subterranean hydrocarbon-bearing formation wherein a substance capable of reacting with hydrogen peroxide is introduced into the formation via an injector well. The resultant mixture of hydrogen peroxide and water is injected to cause an exothermic reaction that increases the temperature of the formation and resident bitumen resulting in a less viscous product with enhanced quality and increased market value.