Device for placing a radioactive source in a formation through which a borehole passes
US4916312A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 1988 |
| Grant date | Apr 10, 1990 |
| Priority date | — |
| Expiry date | Mar 4, 2008 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/116
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The present invention relates to a device for placing a radioactive source into a formation through which a borehole passes. The device includes a gun barrel, a bullet containing a radioactive source and engaged in the barrel, and an explosive device for propelling the bullet towards the formation. The device further includes two items which reduce the speed at which the bullet, when fired, penetrates into the formation. These items are a spacer, placed in the barrel between the bullet and the explosive device, and a braking shield placed at the port end of the barrel. The spacer reduces the effect of the gases produced by the explosive device upon detonation. The braking shield is entrained with the fired bullet, the front end of the shield producing drag which also acts to retard the forward propulsion of the bullet. The shield is designed to break away from the bullet upon formation impact, further reducing the kinetic energy of the bullet. The invention is applicable to soft formations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.