Hydraulic lubricator for use at a wellhead

Abstract

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.

1 . A wellhead lubricator apparatus comprising:
 a barrel portion detachably engageable with a yoke assembly mountable upon a wellhead, the barrel portion comprising:
 a barrel housing; 
 a rod movable coaxially within the barrel housing and having a segment of the rod variably extendable from an end of the barrel housing and into the yoke assembly; 
 a piston secured to the rod and movable within the barrel housing; and 
   hydraulic means for controllably driving the piston to-and-fro within the barrel housing, thereby moving the rod axially in relation to the barrel housing and yoke assembly.   
     
     
         2 . A lubricator apparatus for use at an oil or gas wellhead, comprising:
 a yoke assembly removably mountable to a wellhead, and   a barrel portion, detachably engageable with the yoke assembly, comprising:
 a barrel housing having a first end and a second end; 
 a rod movable coaxially within the barrel housing and having a segment of the rod variably extendable from the barrel housing second end; 
 a piston secured to the rod and movable within the barrel housing, there being defined in the barrel housing a head space between the piston and the barrel housing first end and a barrel space between the piston and the barrel housing second end; 
   an upper port defined in the barrel housing for permitting a hydraulic fluid to enter or exit the head space;   a lower port defined in the barrel housing for permitting hydraulic fluid to enter or exit the barrel space; and   a valve for regulating hydraulic pressure in the head space or the barrel space, thereby controllably driving the piston to-and-fro within the barrel housing and moving the rod axially in the barrel housing.   
     
     
         3 . An apparatus according to  claim 2  wherein the barrel portion has a screwed engagement with the yoke portion by means of a steel swage. 
     
     
         4 . An apparatus according to  claim 3 , wherein the second end of the barrel housing is secured within a female side of the swage by a pressure gland for containing hydraulic pressure within an interior of the barrel housing. 
     
     
         5 . An apparatus according to  claim 4  wherein the swage has a screwed engagement with a union atop the yoke assembly, and the tool rod movably extends axially through the gland and the swage, and into the yoke assembly. 
     
     
         6 . An apparatus according to  claim 2  wherein the valve comprises a valve in fluid communication with the upper port and with the fluid port, and further wherein the lower port and the upper port are in fluid communication with hoses for delivering hydraulic pressure separately to each of the ports. 
     
     
         7 . An apparatus according to  claim 6  wherein the valve comprises a needle valve for controlling hydraulic fluid flow between the upper fluid port and the lower fluid port, whereby the needle valve closed prevents hydraulic fluid from moving directly between the ports while the needle valve open allows hydraulic pressure equalization to occur between the ports.