Downhole steam generator having a downhole oxidant compressor

An apparatus for generation of steam in a borehole comprising:

• an oxidant supply means;
• a fuel supply means for supplying fuel;
• a combustor assembly having a combustion chamber for receiving, mixing and combusting said oxidant and fuel for generating hot combustion gases;
• an igniter means for igniting the fuel and oxidant mixture in said chamber;
• a water supply means for injecting water into said combustion chamber to be converted to steam by the heat of combustion;
• oxidant compressor means for compressing the oxidant prior to injection into said chamber;
• means for driving said compressor means by said hot combustion gases;
• and
• steam outlet means for injecting the hot combustion gases and steam for penetration into the earth formation;
• wherein said compressor comprises a housing, a compression chamber defined by said housing, aligned and connected to said combustion chamber by a central nozzle to feed compressed oxidant to said combustion chamber, a shaft extending axially through said chambers and said central nozzle, bearing means supporting and allowing rotation of said shaft, said driving means including a turbine mounted on said shaft in said combustion chamber.

An apparatus for generation of steam in a borehole for penetration into an earth formation comprising:

• an oxidant supply means;
• a fuel supply means for supplying fuel;
• a combustor assembly having a combustion chamber for receiving, mixing and combusting said oxidant and fuel for generating hot combustion gases;
• an igniter means for igniting the fuel and oxidant mixture in said chamber;
• a water supply means for injecting water into said combustion chamber to be converted to steam by the heat of combustion;
• said oxidant supply means including a plurality of peripheral nozzles around the periphery of said combustion chamber for injection of multiple streams of high pressure oxidant for improved mixing with the fuel and enhanced combustion, wherein said oxidant nozzles are mounted on an annular manifold extending around the periphery of the combustion chamber, and including a central nozzle to feed compressed oxidant to said combustion chamber.

In operation of a downhole steam generation for injecting steam into an earth formation, a method comprising the steps of:

• compressing oxidant downhole to a relatively high pressure by compressor means;
• injecting the high pressure oxidant into a combustion chamber;
• injecting fuel into the combustion chamber to produce a fuel and oxidant mixture;
• igniting the fuel and oxidant mixture thereby producing high pressure expanding combustion gases;
• driving a turbine employing the driving force of the expanding combustion gases;
• powering the compressor means by the turbine;
• transferring the hot combustion gases downstream of the turbine to a steam generation zone;
• injecting water into the steam generation zone to produce steam;
• and
• injecting the steam into the earth formation.