Pull-through tubing string rotator for an oil well

Details Pull-through tubing string rotator for an oil well Pull-through tubing string rotator for an oil well

1999-02-25

2001-03-13

Suchfield, George (Department: 3672)

Wells

Above ground apparatus

With tube rotating means

C166S075140

Reexamination Certificate

active

06199630

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an apparatus for rotating a tubing string within an oil well, and in particular such an apparatus that readily provides for the removal of a tubing string from the oil well by pulling the string through the rotating apparatus.
BACKGROUND OF THE INVENTION
It is well known that through rotating a tubing string in an oil well, the wear that typically occurs on the inside surface of the tubing string caused by sucker rod movement can be reduced or more evenly distributed around the interior surface of the string, thereby significantly extending the life of the string. A variety of different devices have been proposed by others in order to rotate the tubing string. Typically, such devices, or rotators as they are commonly known, are bolted or otherwise attached to the top of an oil well and connected in some manner to the tubing string to cause the string to rotate. In some instances the tubing string may be hung directly from the rotator, while in others a hanging apparatus may effectively hang the tubing string from the well casing. The hanging device would then most often be engaged by a rotator to turn the string.
While such prior art devices are relatively effective in distributing wear around the interior surface of the tubing string, there is little or no standardization of the size of the casing bowls that tubing hangers fit into. There is therefore a need for a wide variety of different tubing string hangers and rotators to match the size of the various different casing bowls that are used. Furthermore, the design of present rotators necessitates that they be completely removed from the oil well in order to withdraw the tubing string, or to remove the downhole pump for servicing or replacement. In many cases the tubing string of an oil well must be pulled as often as every two months in order to repair worn parts or leaks, or to service the pump. Removing the rotator from the wellhead in order to pull the string and the pump increases the amount of labour and equipment required for servicing the well, and also extends the down-time of the well and results in further lost production.
SUMMARY OF THE INVENTION
The invention therefore provides an apparatus for rotating a tubing string within an oil well which permits the tubing string, and a downhole pump attached thereto, to be readily withdrawn from the well without the necessity of removing the entire rotator. The device may also be readily used on casing bowls of a variety of different sizes.
Accordingly, in one of its aspects the invention provides an apparatus for rotating a tubing string within an oil well, the apparatus comprising an outer housing having an upper end, a lower end and a generally hollow interior, said lower end having means for attaching said outer housing to the casing bowl of an oil well; a drive assembly generally disposed within the interior of said outer housing, said drive assembly including a generally hollow rotating gear mandrel and a drive gear; and, a tubing string hanger disposed within said generally hollow interior of said outer housing, said tubing string hanger having a lower end with means for attaching to and supporting a tubing string, said tubing string hanger further having means to operatively engage said tubing string hanger and said rotating gear mandrel such that rotation of said rotating gear mandrel causes rotation of said tubing string hanger, said means to operatively engage said rotating gear mandrel allowing said tubing string hanger, and a tubing string attached thereto, to be withdrawn from the oil well and through said outer housing without withdrawal of said rotating gear mandrel or said drive gear.
Further objects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.


REFERENCES:
patent: 2694450 (1954-11-01), Osbun
patent: 5383519 (1995-01-01), Wright
patent: 5427178 (1995-06-01), Bland
patent: 5465788 (1995-11-01), Wright
patent: 5732777 (1998-03-01), Grimshaw
patent: 5875841 (1999-03-01), Wright et al.
patent: 5964286 (1999-10-01), Cuppen
patent: 6026898 (2000-02-01), Bland et al.

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