Hydraulic well jar
US3955634A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 1975 |
| Grant date | May 11, 1976 |
| Priority date | — |
| Expiry date | Jun 23, 1995 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B31/113
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A hydraulic jar for applying a jarring blow to an object stuck in a well wherein two separate annular fluid chambers are provided in the jar, with one of the chambers confining a body of operating hydraulic fluid and means for restraining relative longitudinal movement of the jar for developing tension and stretch in the drill string so as to produce the jarring blow, and with the second annular fluid chamber confining a body of heavy lubricating fluid and splined portions and jarring surfaces to isolate foreign particles from the operating fluid chamber to prevent or inhibit internal jamming or sticking during actuation. Because the means disposed in the operating fluid chamber are subjected only to forces developed during the pulling stroke, the operating fluid chamber may have a greater area for the development of greater pull loads at lower hydraulic pressures than prior hydraulic jar.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.