Method for explosive expansion toward horizontal free faces for forming an in situ oil shale retort
US4192554A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1978 |
| Grant date | Mar 11, 1980 |
| Priority date | — |
| Expiry date | Jul 31, 1998 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/248
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Formation is excavated from within a retort site in formation containing oil shale for forming a plurality of vertically spaced apart voids extending horizontally across different levels of the retort site, leaving a separate zone of unfragmented formation between each pair of adjacent voids. Explosive is placed in each zone, and such explosive is detonated in a single round for forming an in situ retort containing a fragmented permeable mass of formation particles containing oil shale. The same amount of formation is explosively expanded upwardly and downwardly toward each void. A horizontal void excavated at a production level has a smaller horizontal cross-sectional area than a void excavated at a lower level of the retort site immediately above the production level void. Explosive in a first group of vertical blast holes is detonated for explosively expanding formation downwardly toward the lower void, and explosive in a second group of vertical blast holes is detonated in the same round for explosively expanding formation upwardly toward the lower void and downwardly toward the production level void for forming a generally T-shaped bottom of the fragmented mass.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.