04444256 is referenced by 3 patents and cites 13 patents.

A method for igniting an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale is provided. A void space is in the retort between the top surface of the fragmented mass and the top boundary of overlying unfragmented formation. A hot ignition gas comprising oxygen is introduced into the void space to form a combustion zone across the surface of the fragmented mass. An oxygen-supplying gas is then introduced into the void space for sustaining the combustion zone and for advancing the combustion zone downwardly through the retort. The combustion zone is then extinguished and a cool inert gas is introduced into the retort to cool carbonaceous materials comprising the surface of the fragmented mass to a temperature below the self-ignition temperature of such carbonaceous materials, while leaving carbonaceous materials below the fragmented mass surface at temperatures greater than the self-ignition temperature of such materials. Introduction of the inert gas is then discontinued. Thereafter, an oxygen-supplying gas is re-introduced into the retort to ignite the carbonaceous materials below the surface of the fragmented mass for re-establishing the combustion zone in the fragmented mass and for advancing the combustion zone downwardly through the retort.

Title
Method for inhibiting sloughing of unfragmented formation in an in situ oil shale retort
Application Number
6/404475
Publication Number
4444256
Application Date
August 2, 1982
Publication Date
April 24, 1984
Inventor
Jian C Shen
Houston
TX, US
Agent
Christie Parker & Hale
Assignee
Occidental Research Corporation
CA, US
IPC
E21C 41/10
E21B 43/247
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