The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 25, 1983
Filed:
Dec. 29, 1980
Chang Y Cha, Golden, CO (US);
Occidental Oil Shale, Inc., Grand Junction, CO (US);
Abstract
An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale which is ignited by introducing fuel and air through a passage leading to the fragmented mass. The amount of air provided is in the range of from about 1/3 more than the amount of air required to stoichiometrically combine with the fuel to about twice the amount of air required to stoichiometrically combine with the fuel. The fuel/air mixture is ignited and hot combustion gases pass downwardly into the fragmented mass. The hot combustion gases heat oil shale particles above the self-ignition temperature of such particles, thereby forming a primary combustion zone in the fragmented mass. Introduction of fuel is discontinued when the concentration of oxygen in off gas from the retort decreases to below a first selected value. The surface of the fragmented mass is cooled and then fuel is re-introduced into the retort, forming a secondary combustion zone below the surface of the fragmented mass for spreading the primary combustion zone. When the concentration of oxygen in off gas from the retort decreases below a second selected value, the secondary combustion zone is extinguished.