Packless stuffing box annular seal assembly
An improved annular seal assembly and packless stuffing box for an oil pumping unit of the type having a polished rod reciprocatingly extending therethrough and downhole to a pump located at the lower end of a borehole. The stuffing box has a main body that terminates in a tubing adaptor at the lower end thereof by which it can be mounted to the upper end of the tubing of a wellhead. The main body houses the annular seal assembly that includes a pressure set seal pack for sealingly engaging the polished rod. The polished rod reciprocatingly extends through the seal assembly and main body. The seal assembly includes paired metal annular cones which are capable of sealing under conditions present in the stuffing box. The seal assembly withstands such conditions far longer than traditional seal assemblies, thus reducing cost and downtime of the pumping unit.
This patent application is an original patent application in the United States. No federal funding was used in the development of this invention.
DESCRIPTION Summary of the InventionThe present invention provides a stuffing box having an improved design of a pressure active seal assembly consisting of pairwise arrangements of hollow cones, which adds unexpected long life to the seals thereof.
BACKGROUND OF THE INVENTIONStandard oil pumping units, also known as pumpjacks, have several components that are essential for operation. One such unit is the polished rod, which is visible from the exterior of the unit. The polished rod moves up and down in a vertical plane, when the unit is in operation.
The polished rod moves through a stuffing box, which contain seals that lubricate the polished rod, and yet seal the unit to prevent oil leaks. These seals are often constructed of graphite or other soft, malleable material, in order to closely conform to the motions of the polished rod.
The difficulty with graphite seals, or seals of other soft material, is that they are not durable. Seals must be replaced frequently, at high replacement cost, due to manpower needs, replacement materials, and down time of the pumping unit. Yet, prior to the present invention, it was difficult to engineer hard materials to produce seals of long life and duration.
A primary object of this invention is the provision of an improved stuffing box for a unit, or the like, having a seal assembly mounted within a main body thereof. There is a seal pack included within the seal assembly which is supported within a seal holder therefor. The seal assembly includes a series of pairwise mounted metal hollow conical seals, so configured to fit tightly around the polished rod.
Another object of this invention is the provision of slots in the cones, which allow for expansion and contraction of the cones, according to ambient temperature and pressure conditions. This allows the cones to maintain their function of sealing the rod.
Another object of this invention is to provide a sealing mechanism for a polished rod, which mechanism is comprised of hardened steel or other hard material.
A significant object of the current invention is to provide a sealing mechanism for an oil producing unit that is significantly more durable than current devices of the same service. Thus, an important objective is to provide more time between replacement services for seals in an oil pumping unit.
The above objects are attained in accordance with the present invention by the provision of a combination of elements which are fabricated in a manner substantially as described herein.
The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.
Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner.
The main body of the outer tube 200 has upper and lower end caps, 20 and 40, respectively. The entire unit is designed to fit snugly around a polished rod, at the lower end thereof, near the borehole exit.
A schematic depiction of stuffing box 100 is shown in
When assembled, the cones and main body form a channel 80 into which will fit a polished rod of a pumpjack unit. The rod can move up and down in a vertical plane, or can rotate around its long axis. The present invention will maintain a tight seal and prevent the escape of oil.
An annular seal cone 50 of the preferred embodiment of the current invention is shown in
Turning now to
The entire stuffing box 100 has a cap and a base. The cap is shown in
As shown in
The new combination of the novel packless stuffing box and pressure set seal packs provides new and unobvious and patentable features that reduce the cost of producing an oil well with a pump jack unit.
While the invention has been described in connection with a preferred embodiment or embodiments, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
Claims
1. An annular seal assembly and stuffing box for an oil pumping unit; said seal assembly and stuffing box comprising:
- a housing body having an upper end opposed to a lower end, adaptor means at said lower end by which said housing can be mounted respective to said pumping unit; said housing body having a closure means at said upper end of said main body that forms a cap; a longitudinal passageway extending through said housing body through which said polished rod can extend;
- a seal assembly having a plurality of mated, opposing hollow, annular cones, said cones facing each other base-to-base within each pair, said cone pairs being axially aligned with said polished rod and forming part of said inner surface of said seal assembly for sealingly engaging said polished rod;
- whereby, said seal assembly can seal off and accommodate movement of said polished rod.
2. The stuffing box and seal assembly of claim 1 wherein said housing comprises a cylindrical tube within which said seal assembly fits.
3. The stuffing box and seal assembly of claim 1 and further including a screw cap forming the upper end of said stuffing box.
4. The stuffing box and seal assembly of claim 1 wherein said seal assembly comprises annular cones, wherein each cone has a slot cut entirely through one wall, extending vertically therethrough, from top to base.
5. The stuffing box and seal assembly of claim 1 wherein each said annular cone further comprises a plurality of slots that extend vertically from top to base, but only extend part of the thickness of the wall of the cone from the outer wall toward but not penetrating the inner wall of said cone.
6. The stuffing box and seal assembly of claim 1 wherein each said annular cone further comprises a cut down lower edge of the cone at the base thereof.
7. An improved stuffing box and annular seal assembly of the type that can be connected to a tubing, and having a shaft received therethrough in a sealed manner therewithin and forms a tubing annulus therewith, comprising:
- said box comprising a hollow cylinder, having a longitudinal passageway extending therethrough through which said shaft can be received for either of rotational and reciprocating movement; wherein,
- an axial passageway extends longitudinally through said seal assembly in parallel relationship respective to said longitudinal passageway of said box; a seal pack including pairwise arrangements of hollow truncated cones mounted within said seal holder for sealingly engaging said shaft.
8. The stuffing box and seal assembly of claim 7 wherein said seal pack comprises upper and lower paired annular truncated cone seal elements having a porous oiling channels located therebetween, and passageway means connecting said porous oiling channels for lubricating said seal assembly and said shaft.
9. The stuffing box and seal assembly of claim 7 wherein said shaft is reciprocatingly connected to a pumping unit, said seal assembly is arranged for radial movement within said chamber in a manner such that said longitudinal passageway can be moved in any radial direction within a plane that lays perpendicular to said shaft to thereby accommodate misalignment between a pumping unit horsehead and a vertical axis of a borehole.
10. An annular seal assembly and stuffing box for an oil pumping unit; said seal assembly and stuffing box comprising:
- a housing body having an upper end opposed to a lower end, adaptor means at said lower end by which said housing can be mounted respective to said pumping unit; said housing body having a closure means at said upper end of said main body that forms a cap; a longitudinal passageway extending through said housing body through which said polished rod can extend;
- a seal assembly having a plurality of mated, opposing hollow, annular cones, said cones facing each other base-to-base within each pair, said cone pairs being axially aligned with said polished rod and forming part of said inner surface of said seal assembly for sealingly engaging said polished rod;
- wherein, said cones each have a plurality of slots cut vertically into the walls thereof; and,
- whereby, said seal assembly can seal off and accommodate movement of said polished rod.
Type: Application
Filed: Feb 9, 2007
Publication Date: Aug 14, 2008
Inventor: John Arnold (Bakersfield, CA)
Application Number: 11/704,568
International Classification: E21B 33/02 (20060101);