The United States of America as Represented by the United States

Enhanced Energy Systems

Ronald L Fox

A Burl Donaldson

Anthony J Mulac

Stephen Eisenhawer

A steam generator having substantial thermal capacity for producing high quality steam used primarily for downhole steam generation in tertiary oil recovery. Incorporated in the generator is a novel high pressure, high heat release combustor, utilizing high pressure gaseous fuel and compressed gas oxidizer such as air, wherein thermal and mechanical stresses on the combustor structure are controlled. A method for controlling combustion induced mechanical stresses on the combustor through fluid injection is also disclosed. Disclosed designs provide substantially increased combustor life in 'Downhole' Steam Generation service. The burner employs an ignition technique utilizing gaseous injection of a pyrophoric compound such as triethylborane (TEB).

Steam generator having a high pressure combustor with controlled thermal

A high output, high pressure direct contact steam generator for producing high quality steam particularly suited for use with low grade, low cost fuel. When used in a system incorporating heat recovery and conversion of carryover water enthalpy into shaft horesepower, the unit disclosed provides high quality, high pressure steam for 'steam drive' or thermal stimulation of petroleum wells through injection of high pressure steam and combustion gas mixtures. A particular feature of the burner/system disclosed provides compression of a burner oxidant such as atmospheric air, and shaft horesepower for pumping high pressure feedwater, from a lowest cost energy source such as leased crude, or other locally available fuel.

Direct contact low emission steam generating system and method utilizing

An apparatus for generation of steam in a borehole for penetration into an earth formation wherein a spiral, tubular heat exchanger is used in the combustion chamber to isolate the combustion process from the water being superheated for conversion into steam. The isolation allows combustion of a relatively low pressure oxidant and fuel mixture for generating high enthalpy steam. The fuel is preheated by feedback of combustion gases from the top of the combustion chamber through a fuel preheater chamber. The hot exhaust gases of combustion at the bottom of the combustion chamber, after flowing over the heat exchanger enter an exhaust passage and pipe. The exhaust pipe is mounted inside the water supply line heating the water flowing into the heat exchanger. After being superheated in the heat exchanger, the water is ejected through an expansion nozzle and converts into steam prior to penetration into the earth formation. Pressure responsive doors are provided at a steam outlet downstream of the nozzle and close when the steam pressure is lost due to flameout.

Downhole steam generator using low pressure fuel and air supply

An apparatus for generation of steam in a borehole for penetration into an earth formation wherein feedback preheater means are provided for the fuel and water before entering the combustor assembly. First, combustion gases are conducted from the combustion chamber to locations in proximity to the water and fuel supplies. Secondly, both hot combustion gases and steam are conducted from the borehole back to the water and fuel supply. The water used for conversion to steam is passed in a countercurrent manner through a plurality of annular water flow channels surrounding the combustion chamber. In this manner, the water is preheated, and the combustion chamber is cooled simultaneously, thereby minimizing thermal stresses and deterioration of the walls of the combustion chamber. The water is injected through slotted inlets along the combustion chamber wall to provide an unstable boundary layer and stripping of the water from the wall for efficient steam generation. Pressure responsive doors are provided at the steam outlet of the combustor assembly. The outlet doors and fluid flow functions may be controlled by a diagnostic/control module. The module is positioned in the water flow channel to maintain a relatively constant, controlled temperature.

Downhole steam generator with improved preheating, combustion and

Apparatus and method for generation of steam in a borehole for penetration into an earth formation wherein a downhole oxidant compressor is used to compress relatively low pressure (atmospheric) oxidant, such as air, to a relatively high pressure prior to mixing with fuel for combustion. The multi-stage compressor receives motive power through a shaft driven by a gas turbine powered by the hot expanding combustion gases. The main flow of compressed oxidant passes through a velocity increasing nozzle formed by a reduced central section of the compressor housing. An oxidant bypass feedpipe leading to peripheral oxidant injection nozzles of the combustion chamber are also provided. The downhole compressor allows effective steam generation in deep wells without need for high pressure surface compressors. Feedback preheater means are provided for preheating fuel in a preheat chamber. Preheating of the water occurs in both a water feed line running from aboveground and in a countercurrent water flow channel surrounding the combustor assembly. The countercurrent water flow channels advantageously serve to cool the combustion chamber wall. The water is injected through slotted inlets along the combustion chamber wall to provide an unstable boundary layer and stripping of the water from the wall for efficient steam generation. Pressure responsive doors are provided at the steam outlet for closing and sealing the combustion chamber from entry of reservoir fluids in the event of a flameout.

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Albuquerque, NM, United States of America

Ronald L Fox