A method for heat injection into a subterranean formation is provided. The method utilizes flameless combustion and a gas fired heater having an electrical heated surface for ignition of the gas. The absence of a flame eliminates the flame as a radiant heat source and results in a more even temperature...http://www.google.de/patents/US5404952?utm_source=gb-gplus-sharePatent US5404952 - Heat injection process and apparatus
