Method for explosively expanding a pillar
An in situ oil shale retort is formed in a retort site in a subterranean formation containing oil shale. The in situ retort contains a fragmented permeable mass of formation particles containing oil shale within top, bottom and generally vertically extending side boundaries of unfragmented formation. Formation is excavated to form at least one void in the subterranean formation while leaving zones of unfragmented formation above and below such a void and at least one support pillar of unfragmented formation in the void. Such a pillar of unfragmented formation extends between the zones of unfragmented formation above and below the void and is explosively expanded by use of techniques which minimize shock damage to the zones of unfragmented formation. The techniques, which can be used individually or in various combinations, include placing explosive charges into the top, bottom and middle portions of the pillar. Explosive charges in the middle portion are detonated first, thereby explosively expanding at least a first segment of the middle portion toward the void. Such a first segment is substantially an entire horizontal cross section of the pillar. Thereafter, all of the remaining explosive charges in the pillar are detonated. If desired, the explosive charges in the middle portion can be more energetic than the charges in the top and bottom portions.
- Assignee:
- Occidental Oil Shale, Inc.
- Patent Number(s):
- US 4560206
- OSTI ID:
- 5864780
- Country of Publication:
- United States
- Language:
- English
Similar Records
In situ oil shale retort having horizontally offset pillars
Removal of pillars from a void for explosive expansion toward the void
Related Subjects
040300 -- Oil Shales & Tar Sands-- Drilling
Fracturing & Mining
040401* -- Oil Shales & Tar Sands-- In Situ Methods
True & Modified
BITUMINOUS MATERIALS
BLAST EFFECTS
CARBONACEOUS MATERIALS
CHEMICAL EXPLOSIVES
CHEMICAL REACTIONS
CHEMICAL REACTORS
COMMINUTION
DECOMPOSITION
DESIGN
DETONATIONS
DISTILLATION EQUIPMENT
EMPLACEMENT
ENERGY SOURCES
EQUIPMENT
EXPLOSIVE FRACTURING
EXPLOSIVES
FOSSIL FUELS
FRACTURING
FUELS
IN-SITU PROCESSING
IN-SITU RETORTING
MATERIALS
OIL SHALES
PROCESSING
RETORTING
RETORTS
SHAPED CHARGES