Method of blasting pillars with vertical blastholes
US4353598A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 18, 1980 |
| Grant date | Oct 12, 1982 |
| Priority date | — |
| Expiry date | Apr 18, 2000 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21C41/24
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A fragmented permeable mass of formation particles is formed in an in situ oil shale retort in a subterranean formation containing oil shale. Formation is excavated to form a horizontally extending void in the subterranean formation and a support pillar of unfragmented formation is left in the void for supporting overlying unfragmented formation. The support pillar is prepared for explosive expansion by forming an array of explosive charges along the centerline of the pillar between its opposed free faces. The amount of explosive on each side of the centerline is about equal. Explosive is then detonated in the support pillar for expanding the pillar about equally toward both opposed free faces. Thereafter, explosive is detonated in unfragmented formation above and/or below the void for explosively expanding the formation toward the void to form the fragmented permeable mass of formation particles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.