Method for igniting an in situ oil shale retort
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.
- Assignee:
- Occidental Oil Shale Inc
- Patent Number(s):
- US 4369841
- OSTI ID:
- 6495735
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
040401* -- Oil Shales & Tar Sands-- In Situ Methods
True & Modified
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COMBUSTION
COMMINUTION
DECOMPOSITION
ELEMENTS
ENERGY SOURCES
ENHANCED RECOVERY
EXPLOSIVE FRACTURING
FOSSIL FUELS
FRACTURING
FUEL-AIR RATIO
FUELS
IN-SITU COMBUSTION
IN-SITU PROCESSING
IN-SITU RETORTING
MATERIALS
NONMETALS
OFF-GAS SYSTEMS
OIL SHALES
OXIDATION
OXYGEN
PROCESSING
QUANTITY RATIO
RECOVERY
RETORTING
THERMAL RECOVERY
THERMOCHEMICAL PROCESSES
ZONES