Combined combustion for in-situ retorting of oil shales

摘要

Shale oil is recovered from oil shale formations by rubblizing or otherwise fracturing the formation establishing zones for an oxidizing gas injection and off gas and product recovery, igniting the formation at a point intermediate between the injection and recovery zones which is the first phase of the process causing a heat front to move cocurrent and a combustion front countercurrent to the injected gas stream, followed by a second process phase which occurs when the combustion front reaches the zone of oxidant injection and reverses itself oxidizing the residual organic matter laid down on the retorted shale and supplying additional heat to continue the heat front movement to the product recovery zone and completing the retorting of the shale downstream from the ignition zone while recovering heat from the retorted shale in the form of gas preheat.