Safety sub with asymmetrical wall elastomeric closure for retaining drilling fluids
US5364064A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 1994 |
| Grant date | Nov 15, 1994 |
| Priority date | — |
| Expiry date | Mar 15, 2014 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/106
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A safety sub is disclosed for retaining drilling fluid in the kelly or equivalent and other components of the mud system located above the drill string when pressure drops in the drill string, such as when the circulation pump is turned off in adding a new joint to the drill string. The safety sub includes a pressurized elastomeric cartridge with an elastomeric closure having an asymmetrical wall thickness, preferably achieved by the removal of a chord of material from its external circumference. When internal drilling pressure drops, the external pre-charge pressure closes the elastomeric material by inwardly collapsing the thinner wall portion of the closure. The metallic end pieces of the cartridge are bonded to the elastomeric material during the molding process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.