Two concepts for downhole production of steam for drive operations have been selected for comparative development. The two designs differ in method of transferring heat from hot combustion gases to produce steam. A low pressure combustion design transfers energy to water through a heat exchanger thus enabling the combustion process to be conducted at a pressure less than the injection pressure; a high pressure combustion design mixes the combustion gases directly with water, resulting in the injection of steam and combustion gases into the reservoir.

The comparative development program has included analysis of energy efficiency, computational examination of recovery, core recovery experiments, and field evaluation.

Field tests have been conducted under low reservoir injection pressure (2.76 MPa). The tests were carried out in a 260 m (800 ft) deep reservoir utilizing a 2.5 acre five spot pattern. Data collected from injection and production wells included fluid flow rates, fluid compositions, and energy content. The reservoir conditions were monitored by a combination of global flow measurements and simultaneous core flow tests. Test results have demonstrated that the recovery with the high pressure combustion design is equivalent to the low pressure design at low reservoir pressure. The injection of combustion gases with steam have reduced the quantity of air contaminents released to the atmosphere.

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