CA2520758A1 - Rotating polished rod guide - Google Patents
Rotating polished rod guide Download PDFInfo
- Publication number
- CA2520758A1 CA2520758A1 CA 2520758 CA2520758A CA2520758A1 CA 2520758 A1 CA2520758 A1 CA 2520758A1 CA 2520758 CA2520758 CA 2520758 CA 2520758 A CA2520758 A CA 2520758A CA 2520758 A1 CA2520758 A1 CA 2520758A1
- Authority
- CA
- Canada
- Prior art keywords
- polished rod
- seal
- assembly
- guide shaft
- guide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000007789 sealing Methods 0.000 claims abstract description 37
- 230000013011 mating Effects 0.000 claims description 6
- 230000003068 static effect Effects 0.000 claims description 4
- 230000000750 progressive effect Effects 0.000 description 6
- 238000005086 pumping Methods 0.000 description 4
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 239000010779 crude oil Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/02—Surface sealing or packing
- E21B33/08—Wipers; Oil savers
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
A well pump drive polished rod guide assembly comprising a rotating polished rod guide shaft adapted to position and maintain the polished rod in line with the drive assembly and the pump driven member facilitating the ability to provide for effective polished rod alignment and sealing.
Description
FIELD OF THE INVENTION
This invention relates to downhole progressive cavity pumping arrangements and more particularly to the polished rod guide assemblies used in the driveheads of downhole progressive cavity pumps. The polished rod guide assembly herein described enables the rotating shaft of the polished rod to be effectively stabilized and aligned during operation whilst preventing heat build up and seal degradation.
BACKGROUND OF THE INVENTION
Downhole progressive cavity pumps are used for the conveying of different types of fluids, but are especially well suited for the pumping of very viscous or thick liquids such as crude oil. A downhole progressive cavity pump is operated by a drive string, generally consisting of a polished rod and/or drive string that extends down the well bore. The drive string rotates in the stationary production tubing and is suspended from and rotated by a drivehead assembly. The drivehead assembly is generally mounted to the top of a wellhead, which is attached to the top end of the production tubing. A
polished rod is attached to the upper end of the drive string and extends through the drivehead to the drive string. The pump includes a stator connected to the bottom end of the production tubing and a rotor attached to the bottom end of the drive string. Upon actuation of the pump by rotation of the drive string, the pumped liquid is forced to the surface through the annular space provided between the drive string and the production tubing.
In conventional downhole progressive cavity pump driveheads, a stufFng box is used to seal the annular space between the tubing and the polished rod as well as to align the polished rod in the well bore between the driven member and the driving member. The stuffing box is generally mounted in a bottom end of the drivehead and is used as both a guide and a sealing component for the rotating polished rod. The proposed invention eliminates the conventional stuffing box assembly and replaces it with a polished rod guide assembly. The polished rod guide assembly herein described is able to effectively maintain the alignment between the driving and driven members, eliminating the rod wobble associated with such pumping systems. It is a design that does not generate excess heat and is therefore able to also provide for a simple and effective sealing mechanism.
SUNINIARY OF THE INVENTION
The use of a polished rod and rod string for pumping production wells is well known in the prior art. As the polished rod is rotated by a drive motor at the well-head, the shaft of the pump drive is rotated in concert with the downhole pump, such a system must be provided with an alignment and seal arrangement to ensure that fluids from the well do not leak or escape at the well-head.
In the past, various rotary seals have been incorporated into production wells to prevent both static and dynamic leakage. In addition to basic rotation seals, advanced sealing systems have also been developed which have incorporated additional functionality within the seals, however they all incorporate and require various and/or numerous quantities and types of packing seals as well as secondary guides and the like to stabilize and align the polished rod in the production tubing, all of which have proven to be non effective in the long term operation of a downhole pump.
For example prior art such as U.S. patent application 6,739,390 and 09/433,687 describe a type of gimbal seal and remote guide arrangement for maintaining alignment and a seal on the polished rod. The long-term effectiveness of this type of design remains unproven.
Accordingly, there continues to be a need for way to accurately align and dynamically seal a rotating polished rod which will also be effective in providing static sealing when the pump is not operating and/or the well is being serviced Therefore the present invention provides for a rotating polished rod guide shaft that is located in a bearing cap that is threadedly connected to the top of the well pipe, so that the bearing cap ideally positions and maintains the polished rod in alignment with the drive assembly and the driven assembly. Due to the inherent twisting of the polished rod when it is being driven it is critical to provide the required support to prevent displacement of the polished rod from the most efficient position, that being in the center line of the driving member. By employing an assembly with a single large capacity or dual or multiple bearing set up, the required alignment is easily kept consistent without necessitating the need for an ancillary or secondary bushing or secondary stationary guide assembly or redundant sealing or packing arrangements. Such secondary static guide assemblies tend to generate heat, which destroys the seals and inevitably the guides also wear out. By utilizing an independent rotating polished rod guide shaft assembly for effective alignment and sealing, seal degradation is reduced or eliminated and the need for a secondary alignment means is also eliminated. By maintaining proper alignment no heat is generated from the rotating assembly, prolonging seal life, preventing leaks and extending bearing life.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the upper guide shaft assembly 8, with a dual bearing assembly 12, bearing spacer 13, polished rod guide cinch cap 15, lower guide shaft assembly 10 with guide shaft seal assembly 14, shaft to cap seal 17 and lower shaft external seal 16 and upper shaft external seal 18.
Figure 2 shows the mounting cap 20 with mounting threads 21, cap to pipe seal 19 and guide shaft bearing and seal locating surface 23.
Figure 3 shows the upper guide shaft assembly 8 with polished rod cinch cap locating threads 25, wrench flat 31, bearing and spacer locating surface 27, upper external guide shaft sealing lip 18, upper to lower guide shaft attaching threads 29, internal polished rod to guide shaft seal 24, guide shaft to seal and seal to cap locating surface 22.
Figure 4 shows the lower guide shaft assembly 10 with lower to upper attaching threads 29, lower external guide shaft sealing lip 16 and internal polished rod to guide shaft seal 24.
Figure 5 shows guide shaft seal assembly 14, seal assembly to cap seal 17, lower guide shaft external seal to guide shaft sealing lip 28, upper guide shaft external seal to guide shaft sealing lip 30 and internal guide shaft seals 32.
Figure 6 shows the assembled polished rod guide shaft assembly 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of a polished rod guide shaft in accordance with the invention as shown in FIG. 1 is intended for use with a top drive progressive cavity pump drivehead, or another suitable rotary pump known in the art.
The two piece guide shaft in the figure 1 assembly includes an upper shaft section 8 for locating the bearing assembly 12 and seal assembly 14 and for creating upper sealing and seal assembly mating lip 18. Lower shaft section 10 includes sealing and seal assembly mating lip 16 for sealing lower shaft to seal assembly 14 as well as for locking seal assembly to both upper shaft and lower shaft when assembled. Seal assembly 14 contains internal sealing elements 32 for sealing seal element 14 to guide shaft units 8 and 10.
Sealing element 14 contains external sealing element 17 for sealing the sealing assembly to the mounting cap.
Upper guide section 10 contains internal polished rod sealing element 24 with bearing and seal assembly mounting and locating surface 27. Seal assembly locating and mating lip 18 and seal assembly internal mating and locating surface 22 are located on top of threaded upper to lower attachment means 24.
Lower guide section 10 contains internal polished rod to guide sealing element 24, polished rod guide element 10, seal assembly mating, locating and locking lip 26 below threaded lower to upper guide attachment means 29.
Mounting cap 20 contains bearing and seal mounting surfaces 23 for mounting and locating of bearing assembly 12 and seal assembly 14. Cap is threaded 21 to mount to top of wellhead and has cap to wellhead sealing element 19.
Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the claims.
This invention relates to downhole progressive cavity pumping arrangements and more particularly to the polished rod guide assemblies used in the driveheads of downhole progressive cavity pumps. The polished rod guide assembly herein described enables the rotating shaft of the polished rod to be effectively stabilized and aligned during operation whilst preventing heat build up and seal degradation.
BACKGROUND OF THE INVENTION
Downhole progressive cavity pumps are used for the conveying of different types of fluids, but are especially well suited for the pumping of very viscous or thick liquids such as crude oil. A downhole progressive cavity pump is operated by a drive string, generally consisting of a polished rod and/or drive string that extends down the well bore. The drive string rotates in the stationary production tubing and is suspended from and rotated by a drivehead assembly. The drivehead assembly is generally mounted to the top of a wellhead, which is attached to the top end of the production tubing. A
polished rod is attached to the upper end of the drive string and extends through the drivehead to the drive string. The pump includes a stator connected to the bottom end of the production tubing and a rotor attached to the bottom end of the drive string. Upon actuation of the pump by rotation of the drive string, the pumped liquid is forced to the surface through the annular space provided between the drive string and the production tubing.
In conventional downhole progressive cavity pump driveheads, a stufFng box is used to seal the annular space between the tubing and the polished rod as well as to align the polished rod in the well bore between the driven member and the driving member. The stuffing box is generally mounted in a bottom end of the drivehead and is used as both a guide and a sealing component for the rotating polished rod. The proposed invention eliminates the conventional stuffing box assembly and replaces it with a polished rod guide assembly. The polished rod guide assembly herein described is able to effectively maintain the alignment between the driving and driven members, eliminating the rod wobble associated with such pumping systems. It is a design that does not generate excess heat and is therefore able to also provide for a simple and effective sealing mechanism.
SUNINIARY OF THE INVENTION
The use of a polished rod and rod string for pumping production wells is well known in the prior art. As the polished rod is rotated by a drive motor at the well-head, the shaft of the pump drive is rotated in concert with the downhole pump, such a system must be provided with an alignment and seal arrangement to ensure that fluids from the well do not leak or escape at the well-head.
In the past, various rotary seals have been incorporated into production wells to prevent both static and dynamic leakage. In addition to basic rotation seals, advanced sealing systems have also been developed which have incorporated additional functionality within the seals, however they all incorporate and require various and/or numerous quantities and types of packing seals as well as secondary guides and the like to stabilize and align the polished rod in the production tubing, all of which have proven to be non effective in the long term operation of a downhole pump.
For example prior art such as U.S. patent application 6,739,390 and 09/433,687 describe a type of gimbal seal and remote guide arrangement for maintaining alignment and a seal on the polished rod. The long-term effectiveness of this type of design remains unproven.
Accordingly, there continues to be a need for way to accurately align and dynamically seal a rotating polished rod which will also be effective in providing static sealing when the pump is not operating and/or the well is being serviced Therefore the present invention provides for a rotating polished rod guide shaft that is located in a bearing cap that is threadedly connected to the top of the well pipe, so that the bearing cap ideally positions and maintains the polished rod in alignment with the drive assembly and the driven assembly. Due to the inherent twisting of the polished rod when it is being driven it is critical to provide the required support to prevent displacement of the polished rod from the most efficient position, that being in the center line of the driving member. By employing an assembly with a single large capacity or dual or multiple bearing set up, the required alignment is easily kept consistent without necessitating the need for an ancillary or secondary bushing or secondary stationary guide assembly or redundant sealing or packing arrangements. Such secondary static guide assemblies tend to generate heat, which destroys the seals and inevitably the guides also wear out. By utilizing an independent rotating polished rod guide shaft assembly for effective alignment and sealing, seal degradation is reduced or eliminated and the need for a secondary alignment means is also eliminated. By maintaining proper alignment no heat is generated from the rotating assembly, prolonging seal life, preventing leaks and extending bearing life.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the upper guide shaft assembly 8, with a dual bearing assembly 12, bearing spacer 13, polished rod guide cinch cap 15, lower guide shaft assembly 10 with guide shaft seal assembly 14, shaft to cap seal 17 and lower shaft external seal 16 and upper shaft external seal 18.
Figure 2 shows the mounting cap 20 with mounting threads 21, cap to pipe seal 19 and guide shaft bearing and seal locating surface 23.
Figure 3 shows the upper guide shaft assembly 8 with polished rod cinch cap locating threads 25, wrench flat 31, bearing and spacer locating surface 27, upper external guide shaft sealing lip 18, upper to lower guide shaft attaching threads 29, internal polished rod to guide shaft seal 24, guide shaft to seal and seal to cap locating surface 22.
Figure 4 shows the lower guide shaft assembly 10 with lower to upper attaching threads 29, lower external guide shaft sealing lip 16 and internal polished rod to guide shaft seal 24.
Figure 5 shows guide shaft seal assembly 14, seal assembly to cap seal 17, lower guide shaft external seal to guide shaft sealing lip 28, upper guide shaft external seal to guide shaft sealing lip 30 and internal guide shaft seals 32.
Figure 6 shows the assembled polished rod guide shaft assembly 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of a polished rod guide shaft in accordance with the invention as shown in FIG. 1 is intended for use with a top drive progressive cavity pump drivehead, or another suitable rotary pump known in the art.
The two piece guide shaft in the figure 1 assembly includes an upper shaft section 8 for locating the bearing assembly 12 and seal assembly 14 and for creating upper sealing and seal assembly mating lip 18. Lower shaft section 10 includes sealing and seal assembly mating lip 16 for sealing lower shaft to seal assembly 14 as well as for locking seal assembly to both upper shaft and lower shaft when assembled. Seal assembly 14 contains internal sealing elements 32 for sealing seal element 14 to guide shaft units 8 and 10.
Sealing element 14 contains external sealing element 17 for sealing the sealing assembly to the mounting cap.
Upper guide section 10 contains internal polished rod sealing element 24 with bearing and seal assembly mounting and locating surface 27. Seal assembly locating and mating lip 18 and seal assembly internal mating and locating surface 22 are located on top of threaded upper to lower attachment means 24.
Lower guide section 10 contains internal polished rod to guide sealing element 24, polished rod guide element 10, seal assembly mating, locating and locking lip 26 below threaded lower to upper guide attachment means 29.
Mounting cap 20 contains bearing and seal mounting surfaces 23 for mounting and locating of bearing assembly 12 and seal assembly 14. Cap is threaded 21 to mount to top of wellhead and has cap to wellhead sealing element 19.
Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the claims.
Claims (14)
1. A rotating polished rod guide assembly for use in the sealing and aligning of a polished rod in a downhole rotary pump production operation, the seal and guide assembly, comprising:
a two piece guide shaft for locating the polished rod in the wellhead mounting cap;
said guide shaft sealable to the polished rod and rotatable with the polished rod within the mounting cap;
a wellhead mounting cap containing a bearing assembly for locating the polished rod guide shaft and polished rod in the wellhead with respect to the drivehead;
said mounting cap providing a housing for the bearing and seal assembly for the rotating polished rod guide shaft; and said mounting cap containing a seal for providing a seal between the mounting cap and the production pipe.
a two piece guide shaft for locating the polished rod in the wellhead mounting cap;
said guide shaft sealable to the polished rod and rotatable with the polished rod within the mounting cap;
a wellhead mounting cap containing a bearing assembly for locating the polished rod guide shaft and polished rod in the wellhead with respect to the drivehead;
said mounting cap providing a housing for the bearing and seal assembly for the rotating polished rod guide shaft; and said mounting cap containing a seal for providing a seal between the mounting cap and the production pipe.
2. A polished rod guide as in claim 1 wherein the guide comprises;
a two piece unit that threadly connects the lower portion of the guide to the upper portion of the guide;
said two piece guide providing a mechanical seal locating mechanism on the lower portion of the guide unit creating a sealing point at the juncture of the two guide pieces;
said guide providing for another seal locating mechanism and second sealing point on the upper portion of the two piece guide assembly;
a two piece guide shaft that creates a sealing point when assembled with the guide shaft seal; and a seal locating mechanism so that when the seal is mechanically located on the guide shafts there are two sealing points created between the guide and the guide seal assembly when the two pieces are assembled.
a two piece unit that threadly connects the lower portion of the guide to the upper portion of the guide;
said two piece guide providing a mechanical seal locating mechanism on the lower portion of the guide unit creating a sealing point at the juncture of the two guide pieces;
said guide providing for another seal locating mechanism and second sealing point on the upper portion of the two piece guide assembly;
a two piece guide shaft that creates a sealing point when assembled with the guide shaft seal; and a seal locating mechanism so that when the seal is mechanically located on the guide shafts there are two sealing points created between the guide and the guide seal assembly when the two pieces are assembled.
3. A polished rod guide as in claim 1 wherein the guide comprises either an upper or lower internal seal or a combination of both for sealing the guide to the polished rod.
4. A polished rod guide assembly for use in the drivehead of a downhole rotary pump whereby the driven member, the polished rod, is both stabilized and sealed within the wellhead comprising:
a cap for housing and locating the polished rod guide shaft bearing and seal assembly;
said cap attachable to the wellhead;
a cap for housing and locating the polished rod guide shaft bearing and seal assembly;
said cap attachable to the wellhead;
5. A two piece polished rod guide shaft containing an internal seal or seals for sealing the internal guide shaft portion to the polished rod and being fully fixed and rotatable with the polished rod.
6. A two piece polished rod guide shaft that provides for the placement of a shaft sealing assembly on the guide shaft when shaft is disconnected.
7. A polished rod guide shaft seal assembly comprising;
a seal locating unit for locating the seal or seals assembly on the polished rod guide shaft;
said locating unit comprising at least one sealing edge for mating with the upper and lower guide shaft assembly when assembled for creating a sealing point;
said seal locating unit having an internal rotatable seal or seals assembly for sealing the guide shaft to the locating unit.
a seal locating unit for locating the seal or seals assembly on the polished rod guide shaft;
said locating unit comprising at least one sealing edge for mating with the upper and lower guide shaft assembly when assembled for creating a sealing point;
said seal locating unit having an internal rotatable seal or seals assembly for sealing the guide shaft to the locating unit.
8. A polished rod guide shaft seal assembly comprising;
a seal locating unit for locating the seal or seals assembly in the wellhead mounting cap;
said seal locating unit further comprising an external seal or seals assembly for non-rotationally or static sealing the seal-locating unit to the wellhead-mounting cap.
a seal locating unit for locating the seal or seals assembly in the wellhead mounting cap;
said seal locating unit further comprising an external seal or seals assembly for non-rotationally or static sealing the seal-locating unit to the wellhead-mounting cap.
9. A two piece polished rod guide shaft that provides means for locating a shaft seal assembly and further creating an upper and lower sealing point on the shaft in conjunction with the seal assembly, when the two pieces are interconnected.
10. A two piece polished rod guide shaft that mechanically locates a dynamic rotatable seal assembly on the exterior of the guide shaft and provides for sealing points between the seal assembly and the exterior of the guide shaft.
11. A two piece polished rod guide shaft that has an upper portion for locating a bearing or bearing assembly in a wellhead-mounting cap.
12. A two piece polished rod guide shaft that has an upper portion for locating an external seal assembly below the bearing assembly in a wellhead-mounting cap.
13. A two piece polished rod guide shaft that has a separate lower portion attachable to the upper portion for locking an external seal assembly between the upper portion of the polished rod guide shaft and the lower portion of the polished rod guide shaft.
14. A wellhead-mounting cap for housing the polished rod guide shaft external bearing and seal assembly whereby the guide shaft is suitably aligned and located in the wellhead-mounting cap.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2520758 CA2520758A1 (en) | 2005-09-16 | 2005-09-16 | Rotating polished rod guide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2520758 CA2520758A1 (en) | 2005-09-16 | 2005-09-16 | Rotating polished rod guide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2520758A1 true CA2520758A1 (en) | 2007-03-16 |
Family
ID=37872080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2520758 Abandoned CA2520758A1 (en) | 2005-09-16 | 2005-09-16 | Rotating polished rod guide |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2520758A1 (en) |
-
2005
- 2005-09-16 CA CA 2520758 patent/CA2520758A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |