VR Plug Lubricator

Abstract

A tool for installing and/or extracting a VR plug in a wellhead within a cellar or other cramped space. The tool includes a lubricator having an internal rod, a tubular housing, an elbow or angled joint, and a flexible cable having a connector to grip and release the VR plug. The lubricator drives the cable through the housing and valves to the position where the VR plug will be installed/extracted. Rotating the internal rod of the lubricator threads or unthreads the VR plug to or from the wellhead, respectively.

Description

FIELD OF THE INVENTION

The present invention relates to a lubricator for installing and extracting a valve removal plug (VR plug) in a wellhead. More particularly, the present invention relates to a lubricator for installing and extracting a VR plug in a wellhead positioned in a cellar or other narrow, constricted location.

BACKGROUND OF THE INVENTION

When a valve of a wellhead needs repair or replacement a VR plug is often employed. The VR plug is inserted through the open valve(s) and is ultimately positioned, generally by threading it into position, in the wellhead such that the valve in need of repair is sealed off from fluid flow. Typically, a VR plug is installed using a lubricator attached to the horizontal valve. The lubricator is a long tube which holds pressure while moving an internal tool rod to position and remove the VR plug. Lubricators are well known to those skilled in the art and are often used in running and retrieving operations on a wellhead to manage wellhead pressure during the operation. Examples of prior art lubricators can be found in US 2012/0024521 and U.S. Pat. No. 6,827,147, both of which are incorporated herein by reference for all purposes. When a wellhead is installed below ground level, e.g., in a cellar, there is not enough clearance for the traditional lubricator installation/removal method. Thus operators must dig out an area in the side of the cellar large enough to accommodate the installation and removal of the VR plug. Alternatively, a specialized lubricator, e.g., a telescoping lubricator, which is small enough to fit in the cellar area can be employed. The working conditions in the cellar with the specialized lubricator are still quite cramped.

SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a tool for installing a VR plug into a horizontal valve of a wellhead.

In another aspect, the present invention relates to a tool for installing and extracting a VR plug into a horizontal valve of a wellhead.

In yet another aspect, the present invention relates to a tool a for installing and extracting a VR plug to and from a horizontal valve of a wellhead positioned in a cellar or other cramped space.

In still another aspect, the present invention relates to a tool a for installing and extracting a VR plug to and from a horizontal valve of a wellhead positioned below ground level, the tool being operable from ground level.

These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wellhead positioned in a cellar with the tool of the present invention being lowered down.

FIG. 2 shows the tool of the present invention lowered into the cellar and connected to the wellhead.

FIG. 3 is a cross-sectional view of the tool of the present invention connected to the wellhead.

FIG. 4 is an enlarged cross-section of the tool of the present invention and the VR plug in position in the wellhead.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIG. 1 there is shown a wellhead W positioned within cellar C. As can be seen, there is not much distance between the valves V of wellhead W and the walls of cellar C. The lower end of the tool shown generally as 10 is seen near the upper end of cellar C. To replace or repair one of the valves V, a valve removal (VR) plug is installed to cut off fluid from that valve. Typically, the wellhead outlet connected to the valves has female threads for receiving a threaded VR plug. It will be appreciated that not all the features of a typical wellhead are depicted in the drawings, but such features are common and well understood to those skilled in the art.

Turning to FIGS. 2 and 3, the tool 10 of the present invention has been connected to a valve V, typically a gate valve, of wellhead W. The tool 10 comprises a lubricator 12 connected by elongate tubular housing 16 to an elbow joint 14. Lubricator 12 comprises lubricator barrel 11, tool rod 13, fitting 15, and access window 17. Tool rod 13 extends through barrel 1, fitting 15, and access window 17. As will be explained in detail later, tool rod 13 is axially (longitudinally) movable relative to barrel 11. While tool rod 13 can be axially moved manually using a pipe wrench, e.g., a Parmelee wrench or gear wrench, or other suitable tool through access window 17, it is also possible for tool rod 13 to be connected to a piston 40 (shown in phantom) housed within barrel 11. The piston 40 can be hydraulically/pneumatically driven in a matter well known to those skilled in the art, such that it drives tool rod 13 axially through barrel 11. Such hydraulically driven lubricators are well known to those skilled in the art and an example is shown in US 2012/0024521, incorporated herein by reference for all purposes. Lubricator 12 can have connections 19 which connect by hoses or the like to a source of pressure (not shown) to pressurize and release pressure from the lubricator in a manner well known to those skilled in the art. The pressurization of lubricator 12 can be accomplished hydraulically, pneumatically, electrically, or manually. It will be appreciated that the exact placement and configuration of the connections can vary. Additionally, lubricator 12 and connections 19 can include, seals, valves, and control features not shown but which are well known to those skilled in the art. The pressure in lubricator 12 is shown by pressure gauge 21.

As depicted, the elbow joint 14 is 90° but the exact angle of the joint can vary slightly, provided the tool is able to connect to the valve V. As depicted in the drawings, lubricator 12, tubular housing 16, and elbow joint 14 are separate pieces connected to one another by flange nuts 23, it will be understood that some or all of these components could be monolithically formed.

Turning to FIGS. 3 and 4, the details of the tool 10 can be seen. As noted, a tubular housing 16 is connected between lubricator 12 and elbow joint 14. A threaded adapter flange 18 is connected by bolts 25 to the flange of a valve V of wellhead W. A flexible steel cable 20 is extends through the tubular housing 16. A fitting 22 at the upper end of cable 20 connects steel cable 20 to tool rod 13 of lubricator 12. An adapter 24 at the other end of cable 20 is releasably connected to a VR plug 50. In a preferred embodiment, centralizers 30 are spaced along cable 20 to reduce friction and allow free rotation of cable 20. Tubular housing 16 can vary in length depending on the size of the wellhead.

As shown in the figures, there are two valves through which the VR plug 50 must travel. Tool 10 of the present invention can also be used on a wellhead with a single valve or more than two valves. Thus, while the description of the figures will be with respect to two valves, the invention is not so limited.

To install a VR plug 50 in a wellhead W, tool 10 is lowered into cellar C and is connected to valve V1 by adapter flange 18 and bolts 25. Valves V1 and V2 are opened by turning handles H1 and H2, respectively. The pressure of the wellhead is determined by means well known to those skilled in the art, and lubricator 12 is pressurized by the pressure source (not shown) through connections 19 to equalize or match the pressure in lubricator 12, tubular housing 16 and elbow joint 14 with the pressure of the wellhead W. The pressurization of the lubricator is a process well known to those skilled in the art and will not be described in detail. The pressure within a wellhead can be anywhere in the range of from 0 psi to 10,000 psi. Even at 0 psi, a person of skill in the art would want to use the lubricator of the present invention as a safety precaution, e.g., in case of down hole plug failure. Matching the pressure with the pressure of the wellhead ensures that the VR plug 50 does not need to be driven against high pressure coming from the wellhead and makes VR plug installation easier and safer. Piston 40 in barrel 11 is actuated to drive tool rod 13 downward. Alternatively, as described above, tool rod 13 can be driven downward manually with the use of a wrench or other gripping tool. The downward or axial driving of tool rod 13 in turn drives cable 20, and accordingly VR plug 50, through valves V1 and V2. When the VR plug 50 is in position, tool rod 13 is rotated clockwise. This in turn rotates cable 20 and VR plug 50. As noted above, the wellhead and VR plug are threaded such that the rotation threadedly fixes VR plug 50 in position in wellhead W. Tool rod 13 can be rotated manually using a wrench to turn fitting 15 in access window 17 or by other means well known to those skilled in the art. Once VR plug 50 is installed, adapter 24 of cable 20 is released from VR plug 50 and the pressure on tool rod 13 is released to raise tool rod 13 back up (or tool rod 13 is raise back up manually) and accordingly pull cable 20 back into tubular housing 16. The pressure from the lubricator 12 can be bled off, again by a process well known to those skilled in the art. Tool 10 can then be disconnected from valve V1.

To extract the VR plug 50, tool 10 is again lowered into cellar C and is connected to valve V1 by adapter flange 18 and bolts 25. Tool rod 13 is driven down by the actuation of piston 40 or manually, thereby driving cable 20 through valves V1 and V2 until adapter 24 connects with VR plug 50. The pressure in the wellhead is determined by means well known to those skilled in the art and the pressure in lubricator 12 is again equalized to the wellhead pressure on VR plug 50. This ensures that as soon as VR plug 50 is disconnected from the wellhead, the pressure from the wellhead does not send VR plug 50 shooting outwards. Tool rod 13 of lubricator 12 is rotated counterclockwise to unscrew VR plug 50 from wellhead W. Tool rod 13 is then retracted, either by releasing pressure on piston 40 or by manually retracting it. The retraction of tool rod 13 pulls cable 20 and VR plug 50 out of the valves/wellhead. Once VR plug 50 is fully retracted, valves V1 and V2 are closed. The pressure in lubricator 12 can be released, and adapter flange 18 can then be disconnected from valve V1.

It will be understood by one of skill in the art, that the connection and release mechanism of adapter 24 to and from VR plug 50 can vary. For example, the VR plug may have left hand threads on the end connectable to the adapter and right hand threads on the end to be connected in the wellhead. In such case, the VR plug is threadedly connected to the adapter. During installation, the clockwise rotation of cable 20 threads the VR plug into the wellhead. Once the VR plug is fully in place, further clockwise rotation of cable 20 unthreads the adapter 24 from VR plug 50. Likewise, when extracting the VR plug, counterclockwise rotation will thread adapter 24 onto VR plug 50 and once it is connected, further counterclockwise rotation will unthread VR plug 50 from the wellhead. This is simply one method of connecting and releasing adapter 24 from VR plug 50. There are other means of releasably connecting adapter 24 to VR plug 50 that are well known to those skilled in the art.

It will further be understood by those skilled in the art that depending on the type of wire used in the tool, that it may be necessary to have two versions of tool 10, namely, a left hand version and a right hand version. Steel cables are often formed of smaller braided or twisted wires. These braided wires can only be rotated one direction, as rotating the opposite direction would unbraid or untwist the wires. Apart from the direction of the wire braid and thus the permissible direction of rotation, all other features would be the same between the left hand and right hand versions of tool 10. Alternatively, cable 20 could be formed from anti-twisting steel rope or coated with a flexible coating which prevents wire separation. In such a case, a single version of tool 10 could accomplish both installation and extraction of a VR plug.

The present invention provides multiple advantages over the prior art. It allows for the installation of VR plugs in narrow cellars or other difficult to reach areas. It eliminates the need for digging out trenches and work spaces in cellars, thus saving time and money. Workers can operate the tool from ground level. It thus improves safety by allowing workers to operate at a distance from the valves.

Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.

Claims

1. An apparatus for installing a VR plug in and/or extracting a VR plug from a wellhead, comprising: a lubricator comprising an axially movable tool rod, said lubricator being operative to hold pressure equal to that of said wellhead during the installation and/or extraction of said VR plug;an elongate tubular housing having a first end and a second end, said first end of said housing being connected to said lubricator;an elbow joint having a first end and a second end;said first end of said elbow joint being connected to said second end of said housing, said second end of said elbow joint being releasably connectable to a valve on said wellhead;a flexible cable running through said housing and said elbow joint, said cable having a first end operatively connected to said tool rod and a second end having an adapter releasably connectable to said VR plug;whereby when said second end of said elbow joint is connected to said valve on said wellhead and when said valve is in the open position, said tool rod can be driven downwardly which in turn drives said wire through said housing, said elbow joint, and said valve such that said adapter is positioned at a point wherein said adapter can either release said VR plug to be installed, or connect to said VR plug to be extracted.

2. The apparatus of claim 1, wherein rotation of said tool rod rotates said cable such that rotation of said tool rod and cable in a first direction threads the VR plug into the wellhead and rotation of said tool rod and cable in a second direction unthreads said VR plug from the wellhead.

3. The apparatus of claim 1, wherein said axially movable tool rod is connected to a piston, said piston being hydraulically or pneumatically driven to move said tool rod.

4. The apparatus of claim 1, further comprising a plurality of centralizers disposed on said flexible cable.

5. The apparatus of claim 1, wherein said housing and said elbow joint are monolithically formed.