Wells – With below and above ground modification – Above ground actuating means for below ground device
Reexamination Certificate
1999-11-24
2001-04-03
Schoeppel, Roger (Department: 3672)
Wells
With below and above ground modification
Above ground actuating means for below ground device
C166S077510, C166S378000
Reexamination Certificate
active
06209633
ABSTRACT:
TECHNICAL FIELD
This invention relates to the handling of downhole well tools and tubing strings, and in particular to an apparatus for axially displacing a downhole well tool or tubing string in a well bore equipped with a wellhead, the downhole well tool being supported by a tubing string in the well which includes a telescoping joint to permit the axial displacement of the downhole well tool and the tubing string. As well as any downhole operation in which well tubulars or downhole equipment is manipulated or downhole operations are performed in which pressure containment is necessary.
BACKGROUND OF THE INVENTION
Downhole operations and the handling of downhole well tools in completed wells has always presented a certain challenge, especially when working in wells having a natural pressure that exceeds atmospheric pressure, necessitating the containment of the well at all times. A further challenge has been the maintenance of well bores which pass through production zones that are not well suited to continuous production. For example, a production zone which yields both water and oil or gas or any combination thereof may require relatively frequent repositioning of a lower end of a production tubing in order to recover oil or gas efficiently. Production zones which produce crude oil high in waxy compounds or asphaltines, or laden with salts, which tend to plug casing perforations and therefore require frequent treatment to maintain an economic flow of hydrocarbon are further examples of such production zones.
To date, the maintenance of such wells has proven time-consuming and expensive. For example, in wells which produce both oil, water and gas and/or water and gas and have a mobile water/hydrocarbon interface, the production of hydrocarbon gradually decreases over time until only water or gas is produced from the well. Relocation of the bottom end of the production tubing string is then required to recommence oil production. The relocation of the tubing string has been a complex process which involved many time-consuming and expensive steps that are well known in the art. It is not difficult to appreciate that there is a need for a more efficient and less costly system for producing oil or gas from such wells. Such a system is described in applicant's copending patent application incorporated herein by reference. The apparatus described in that patent application eliminates many of the shortcomings of prior art procedures for selectively producing fluids from wells, performing barefoot completions of well bores in sensitive zones, and other downhole operations using production tubing and tools that require axial displacement within a limited range in a well bore. At the time of filing that patent application, it was considered that the apparatus described in U.S. Pat. No. 4,867,243 which issued on Sep. 19, 1989 to Garner et al. would be suitable for effecting the axial displacement of the downhole well tools. It has now been recognized that such prior art tools for inserting mandrels through wellheads is not necessarily adequate or optimal for performing the axial displacement of such downhole well tools.
There are several reasons why such prior art tools are not optimal tools for this purpose. First, they are designed for inserting wellhead isolation mandrels into wellheads and withdrawing them from the wellheads after the well is serviced. Since wellhead isolation mandrels are of inconsequential weight, they are stroked through a wellhead relatively easily. Moving a tubing string of 4,500′ (1,500 meters), which is not uncommonly encountered in handling downhole well tools, may require a force in excess of 50 tons. The force required is due not only to the considerable weight to be lifted but also to the extra force required to unseat anchors and/or packers supporting the tubing string. Such forces may subject the wellhead to potentially damaging stresses. Second, wellhead isolation tools provide no mechanism for rotating a downhole tubing string since rotation is not required for the insertion or withdrawal of a wellhead isolation mandrel. When manipulating a downhole tubing string, however, rotational movement is often required in order to release or set components such as packers, anchors, hangers and the like. Considerable rotational force may be required to accomplish the release of such components and it is therefore desirable to provide a mechanism for selectively rotating the downhole string as required.
It has also now been recognized that certain downhole operations can be more economically performed through the wellhead with pressure containment than performing those operations using a rig, for example. It is also known that certain near-surface operations such as the drilling out of permanent bridge plugs, cement plugs or any other obstruction in the casing column during re-entries require pressure containment in order to avoid the escape of hydrocarbons to atmosphere and potentially dangerous releases of contained pressure. There therefore exists a need for an apparatus which is adapted to provide pressure containment while enabling downhole manipulations to move production tubing, and remove near-surface obstructions with or without the use of a telescoping joint in a tubing string.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead which is robust enough to permit a lengthy tubing string to be displaced in the well bore.
It is a further object of the invention to provide an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead which permits a tubing string alone or a tubing string supporting the downhole tool to be rotated, if required.
It is yet a further object of the invention to provide an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead which is stabilized to reduce stress on the wellhead.
It is yet a further object of the invention to provide an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead which is safe to use.
It is also an object of the invention to provide an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead which is readily transported from one well bore to another.
It is a further object of the invention to provide an apparatus for performing downhole operations which require pressure containment at the wellhead.
These and other objects of the invention are realized in an apparatus for axially displacing a downhole tool or tubing string in a well bore equipped with a wellhead, the downhole tool being supported by a tubing string in the well which includes a telescoping joint to permit the axial displacement of the tool, comprising:
a lift rod string;
a tool entry spool adapted to be mounted to a top of the wellhead;
at least one annular seal for containing well pressure mounted above the tool entry spool, the annular seal providing a fluid seal around a periphery of the lift rod string;
means for axially displacing the lift rod string;
means for selectively rotating the lift rod string; and
a swivel joint for enabling free rotational movement in a link rod between the means for axially displacing the lift rod string and the means for selectively rotating the lift rod string.
The apparatus in accordance with the invention includes a lift rod string which is equipped with a releasable latch tool for connecting a free end of the lift rod string to a latch point in or near a telescoping joint described in applicant's copending patent application, or connected directly to a tubing string. The lift rod string is supported on its top end by a stem which is connected to the means for selectively rotating the lift rod string. The means for selectively rotating the lift rod string is preferably a motor. A hydraulic or an electric motor or a mechanical rotational device can be used. Attached
Nelson Mullins Riley & Scarborough LLP
Schoeppel Roger
LandOfFree
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