Direct firing downhole steam generator

A direct firing downhole steam generator, comprising:

• an injector assembly being defined by an inlet zone, an outlet zone and circumferential walls and having:
• means for introducing air into said injector assembly;
• means for introducing fuel into said injector assembly;
• means for mixing said fuel and said air;
• means for igniting said fuel air mixture;
• and
• means for introducing water into and through said circumferential
• walls of said injector assembly;
• a combustion chamber being defined by an inlet zone, an outlet zone and circumferential walls and wherein said inlet zone of said combustion chamber is axially connected to said outlet zone of said injector assembly, and wherein said combustion chamber walls comprise a plurality of longitudinally-oriented water channels and wherein said water channels are connected to said outlet zone of said injector assembly so as to receive the water from said injector assembly;
• a heat exchanger being defined by inlet and outlet zones and inner and outer circumferential walls and wherein said inlet zone of said heat exchanger is axially connected to the outlet zone of said combustion chamber, and wherein the inlet zone of the annulus formed by said heat exchanger inner and outer walls is connected so as to receive the output of said water channels and wherein said heat exchanger further comprises a plurality of one-way valves oriented so as to permit water to be injected from said annulus into the core of said heat exchanger;
• and
• a nozzle disposed so as to receive the output of said heat exchanger and inject high pressure products into a formation.