Rock bolting techniques for forming an in situ oil shale retort
A subterranean formation containing oil shale is prepared for in situ retorting by forming a fragmented permeable mass of formation particles containing oil shale in an in situ oil shale retort site. Formation is initially excavated from the retort site for forming one or more voids extending horizontally across the retort site, leaving a zone of unfragmented formation adjacent such a void. In one ambodiment, an array of rocks bolts are anchored in at least a portion of the roof adjacent such a void for providing reinforcement of unfragmented formation above the void. Vertical blasting holes are drilled in the zone of unfragmented formation adjacent the void. Explosive is placed in the blasting holes and detonated for explosively expanding the zone of unfragmented formation toward the void, including the rock bolted portion of the roof, for forming at least a portion of a fragmented permeable mass of formation particles containing oil shale in an in situ oil shale retort. Surprisingly, the rock bolting does not interfere with, and in some instances can improve, fragmentation compared with comparable blasts without such rock bolts. The reinforcement provided by the rock bolts can reduce or eliminate the need for roof support pillars in horizontal voids at intermediate levels of the retort site.
- Assignee:
- Occidental Oil Shale Inc
- Patent Number(s):
- US 4281877
- OSTI ID:
- 6158653
- Resource Relation:
- Patent File Date: Filed date 2 Nov 1979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
OIL SHALE DEPOSITS
EXPLOSIVE FRACTURING
SUPPORT PILLARS
OIL SHALES
IN-SITU RETORTING
ANCHORS
MINING EQUIPMENT
ROOF BOLTS
SAFETY ENGINEERING
SUPPORTS
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COMMINUTION
DECOMPOSITION
ENERGY SOURCES
ENGINEERING
EQUIPMENT
FOSSIL FUELS
FRACTURING
FUELS
GEOLOGIC DEPOSITS
IN-SITU PROCESSING
MATERIALS
MECHANICAL STRUCTURES
MINERAL RESOURCES
PROCESSING
RESOURCES
RETORTING
040401* - Oil Shales & Tar Sands- In Situ Methods
True & Modified
040300 - Oil Shales & Tar Sands- Drilling
Fracturing & Mining