| 20120024521 | Hydraulic lubricator for use at a wellhead - A lubricator for use at a wellhead such as an oil or natural gas well. The lubricator has a polished rod on which an item, such as a back pressure valve, may be disposed for placement, for example to isolate the wellhead from the well pressure to permit wellhead servicing. The rod is moved by hydraulic power, rather than manually. A piston is connected to the polished rod within the lubricator barrel. Hydraulic pressure within the barrel, above or below the piston, is controlled to cause the rod to move up and down, under power, to permit the rod and items thereon to be lowered and retrieved. | 02-02-2012 |
