Patent Application
20190277281
The present invention relates to the field of oil and gas wellhead equipment. More particularly, the present invention relates to progressing cavity pumps.
Progressing cavity pumps, which are also known as screw pumps and Moineau pumps, are commonly used for oil and gas well recovery and extraction projects. This type of pump is used to lift fluid from oil and gas wells where there is not enough reservoir pressure to lift the produced fluids to surface. They are increasingly used for artificial lift, and have been adapted to a range of challenging lift situations, including heavy oil production, high sand oil production, oil production from gassy wells, and oil production from directional and horizontal wells.
Progressing cavity pumps operate by lifting fluids to the surface by employing a positive displacement principle. A typical progressing cavity pump features a suction inlet at the end of production tubing which feeds into an elongated casing lining a well bore. The production tubing is typically formed by connecting together a number of tubing sections into a string. The progressing cavity pump includes a helical ‘worm’ rotor and stator assembly. The stator is run into the casing on the bottom of the production tubing, while the rotor is run into the production tubing, connected to the bottom of a continuous sucker rod, or a string of sucker rods 26. The top end of the sucker rod, or sucker rod string is connected to a polished rod, which is in turn connected to an above ground drive system 30.
Above ground drive systems are typically electrically or gas/hydraulic driven. The above ground drive system which moves the rotor in an eccentric fashion within the stator. Cavities formed between the rotor and the stator draw in fluid, and are ‘progressed’ through the rotor and stator assembly and up the production tubing to the surface where it is discharged to the flow line through the pumping tee.
Connected above the pumping tee, a stuffing box includes a seal to keep pressurized well fluids from escaping from the production tubing. The stuffing box preferably forms a tight seal with the polished rod to divert the produced fluids out of the pumping tee into the flow line.
One problem with prior art progressing cavity pumps is that once the progressing cavity pump has been installed, there is no way to check or adjust the depth of the rotor correctly, without disassembling major portions of the above ground equipment. In fact, once the rotor has been installed to the required depth, the standard procedure is to run the progressing cavity pump to acquire production, without ever checking or adjusting the rotor. However, if the rotor was installed at an incorrect depth to begin with, or has slipped down in the production tubing overtime during its operation, the lifespan and efficiency of the progressing cavity pump may be reduced significantly.
Another problem with prior art progressing cavity pumps is that they need to be serviced regularly and often to flush out any build up of debris such as sand, wax, paraffin's, and shale's, and the service is difficult and time consuming. However, the flush-by service also requires disassembling major portions of the above ground equipment.
Prior art methods for checking the depth of the rotor, and for effecting the flush-by service on prior art progressing cavity pumps involve disassembling major portions of the above ground equipment, including the above ground drive system, the stuffing box, and the piping tee, to allow the rotor attached to the end of the rod sting to be lowered within the production tubing to the bottom out in the stator or to some other reference point, as is needed to set the rotor to the correct depth. This is a difficult and time consuming, labour intensive process, and leads to significant downtime.
Accordingly, there is a continued need for improvement in progressing cavity pumps.
What is desired is an improved progressing cavity pump, including an improved polished rod, and slider tool, and methods that provide a safe way to check and adjust the depth of the rotor after the progressing cavity pump has been installed and pumping for a period of time, without needing to disassemble major portions of the above ground equipment.
Also desirable is an improved progressing cavity pump, including an improved polished rod, and slider tool, and methods that permit checking and adjusting the depth of the rotor after flushing out debris buildup in a progressing cavity pump, without needing to disassemble major portions of the above ground equipment.
According to an aspect of the present invention, there is disclosed an improved progressing cavity pump, having an improved polished rod that is attachable to a slider tool, that enables the rod string, including the rotor to be lowered into the production tubing without requiring disassembly of the above ground equipment. Preferably, the slider tool functions to extend the length of the improved polished rod, and the connection between the slider tool and the improved polished rod is preferably configured to ensure that the outside diameter of the connection is no larger than the passageways of the above ground equipment it needs to pass through, when it is lowered.
According to another aspect of the present invention, there is disclosed an improved polished rod clamp, which preferably, has at least one extended nut.
According to another aspect of the present invention, there is disclosed an indicator which enables an operator on the ground to visually determine whether a progressing cavity pump is operating, or whether it is operating correctly.
According to another aspect of the present invention, there is disclosed a method of making the above improved progressing cavity pump by replacing a conventional polished rod in a conventional progressing cavity pump with the improved polished rod according to an embodiment of the present invention.
According to another aspect of the present invention, there is disclosed a method of checking or adjusting the depth of the rotor in the above improved progressing cavity pump.
According to another aspect of the present invention, there is disclosed a method of flushing the above improved progressing cavity pump.
According to another aspect of the present invention, there is disclosed a progressing cavity pump system comprising the above improved polished rod and the above slider tool. Preferably, the system may further include one or more of the above improved polished rod clamp and the above indicator.
According to another aspect of the present invention, there is disclosed a kit comprising the above improved polished rod, and the above slider tool. Preferably, the kit may further include one or more of the above improved polished rod clamp and the above indicator.
Reference will now be made to the preferred embodiments of the present invention with reference, by way of example only, to the following drawings in which:
The present invention is described in more detail with reference to exemplary embodiments thereof as shown in the appended drawing. While the present invention is described below including preferred embodiments, it should be understood that the present invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments which are within the scope of the present invention as disclosed and claimed herein.
A surface-driven progressing cavity pump 10 is shown in
A pumping tee 20 is connected to the top of the production tubing 16 to provide a flow connection from the production tubing 16 to a flow line 22.
A stuffing box 24 connected to the top of the pumping tee 20, includes a seal to keep pressurized well fluids from escaping from the production tubing 16.
A drive system 26 is mounted to the top of the stuffing box 24. Drive systems 26 may be electrically or gas/hydraulically driven. In the example shown in
The surface driven progressing cavity pump 10 includes a polished rod 34, which is inserted from the top of the drive system 26, through the transmission unit 30, the stuffing box 24, the pumping tee 20, to project its one end, herein referred to as its bottom end 36, into the production tubing 16, while its other end, herein referred to as its top end 38, projects upwardly from the drive system 26. The transmission 30 features a hollow drive shaft 40 extending upwardly. The top of the hollow drive shaft 40 preferably includes a receiver for supporting and engaging a polished rod clamp 42, which may be clamped to the top end of the polished rod 34. By the engagement of the receiver at the top of the hollow drive shaft 40 with the polished rod clamp 42, rotation of the hollow drive shaft 40 by the transmission unit 30 is translated to a rotation of the polished rod 34.
Accordingly, it will now be understood that the drive system 26 may be used to drive the rotation of the polished rod 34 of the surface driven progressing cavity pump 10, according to an embodiment of the present invention. As shown in
Preferably, the stuffing box 24 and the pumping tee 20 form tight seals with the polished rod 34 to divert the produced fluids out of the pumping tee 20 into the flow line 22, as the polished rod 34 is rotated by the drive system 26. Preferably, a “composite” pumping tee may be used, which clamps on to the polished rod 34 to support the rod string 44 and seal against the polished rod 34 to isolate produced well fluids. The composite pumping tee allows the stuffing box 24 and the drive system 26 to be serviced or removed safely without having to pull the rod string 44, connected to the polished rod 34 in the production tubing 16, in the ground 14.
With reference now to
As the rotor 52 begins to move in an eccentric fashion, driven by the drive system 26, cavities formed between the rotor 52 and the stator 50 draw in fluid, and are ‘progressed’ through the rotor and stator assembly 48 and up the production tubing 16 to the surface where it is discharged to the flow line 22 connected to the pumping tee 20. Thus, rotation of the rod string 44 by means of the drive system 26 causes the rotor 52 to spin within the fixed stator 50, creating the pumping action necessary to produce fluids to the surface.
Preferably, the progressing cavity pump 10 may also include a tag bar 56 to allow the rotor 24 to be positively located relative to the stator 22. For example, some Installation methods include running the rotor 52 to the tag bar 56 and then spacing back to align the rotor 52 within the stator 50. The rotor space-out is unique to the pump geometry, well operating conditions, and rod string configuration, as is known in the art.
It is also contemplated that large progressing cavity pumps 10 may preferably include a no-turn device 58 to prevent the torque in the rotor and stator assembly 48 from loosening the connections between the tubing sections of the production tubing 16. Smaller progressing cavity pumps 10 with properly torqued tubing sections may not require no-turn devices 58 although a no-turn device may still be included as a precaution. In the example of the progressing cavity pump shown in
For comparison, a conventional polished rod 62 is shown in
A polished rod 34 according to an embodiment of the present invention is shown in
By way of example, the diameter of the body 64 of the polished rod 34 may be sized in a range of ¾ inch to 2½ inches, and its length may be sized in a range of 6 to 60 feet, to coincide with standard sizes, as is known in the art. Similarly, the diameters of the threaded male portions 66 may be sized in a range of ¾ inch to 2½ inches, and their lengths may be sized in a range of ¾ inch to 3 inches, to coincide with standard sizes of rod couplers 46, as is also known in the art.
However, in contrast to a conventional polished rod 62, the polished rod 34, according to the present invention preferably further includes a threaded extension 68 extending coaxially from the top, bottom, or both ends 38,36 of the body 64.
With reference now to
Preferably, the top end 38 may be sized and shaped to the same as the end of a conventional sucker rod 54. Alternately, it is contemplated that the top end 38 of the slider tool 72 may have a threaded male portion 66, sized and shaped to be threadingly connectable to the flush-by/service rig, either directly, or via a rod coupler 46. The bottom end 36 may preferably have a threaded female portion 74, with a substantially flat bottom edge 76. Preferably, the threaded female portion 74 may be sized and shaped to match the threaded extension 68 of the polished rod 34. Accordingly, the diameter of the threaded female portion 74 of the slider tool 72 may be sized in a range of ½ inch to 1½ inches, and the length may be sized in a range of ½ inch to 4 inches. By way of example, the diameter of the body 64 of the slider tool 72 may be sized in a range of ¾ inch to 2½ inches, and its length may be sized in a range of 1 to 7 feet.
However, it is also contemplated that the position of the threaded extension 68 and the matching threaded female portion 74 may be reversed between the polished rod 34 as shown in
What is important is that the slider tool 72 may be threadingly connected to the polished rod 34, via the threaded connection between the threaded extension 68 on one of the polished rod 34 and the slider tool 72, and the threaded female portion 74 on the other of the polished rod 34 and the slider tool 72. If the threaded extension 68 is provided on the polished rod 34, the substantially flat bottom edge 76 of the slider tool 72 may preferably be seated against the substantially flat surface 70 of the polished rod 34. Similarly, if the threaded extension 68 is provided on the slider tool 72, the substantially flat surface 70 of the slider tool 72 may preferably be seated against the substantially flat top edge 76 of the polished rod 34. As will be apparent from the discussion below, the body 64 of the slider tool 72 preferably has an outside diameter that will allow it to pass through the drive system 26, including through the transmission unit 30, through the stuffing box 24, and through the pumping tee 20, and into the production tubing 16, without needing to disassemble or move the above ground equipment out of the way. Preferably, the outside diameter of the body 64 of the slider tool 72 may be no larger than the outside diameter of the body 64 of the polished rod 34 to which it may be attached. Most preferably, the body 64 of the slider tool 72 may have substantially the same outside diameter as the outside diameter of the body 64 of the polished rod 34 to which it may be attached. However, it is also contemplated that the body 64 of the slider tool 72 may have an outside diameter that is smaller than the outside diameter of the body 64 of the polished rod 34 to which it may be attached.
Furthermore, the outside diameter of the slider tool 72 may be larger in some embodiments where the configuration of the above ground equipment permits the larger diameter slider tool 72 to pass therethrough. All such embodiments are comprehended by the present invention.
Preferably, the threaded extensions 68 may be formed in the body 64 of a conventional polished rod 62 (or a conventional sucker rod 54) by machining one or both ends 36,38, or the like. It will now be appreciated that conventional polished rods 62 may be retrofitted in this way to provide a threaded extension 68 at one or both ends 36,38, according to embodiments of the present invention. The machining step may require machining the threaded male portion 66 as well to extend it to a desired length, as some of its length will have been taken by the newly formed threaded extension 68. Alternately, a new polished rod 34 may be made to include the threaded extension 68 at one or both ends 36,38 of the body 64 from the start, by machining, or other methods which are known in the art. Further, it is contemplated that when modifying a conventional polished rod 62, or making a new polished rod 34, according to the present invention, the threaded male portion 66 may be omitted entirely at one or both ends 36,38 having a threaded extension 68, for example as shown in
Referring now to
Preferably, the top end 36 of the slider tool 72 is sized and shaped for attachment to a flush-by or service rig, for example, which can lower the entire rod string 44, after the polished rod clamp 42 has been removed, down the production tubing 16 to a landed position at the bottom of the well bore 12, or to some other desired depth. It will now be apparent, that the slider tool 72, provides a removable extension to the polished rod 34, to allow lowering of the polished rod 34, and thus the connected rod string 44 and rotor 52, without needing to disassemble or move out of the way, the above ground drive system 26, the stuffing box 24, the piping tee 20, and any other intervening above ground equipment. After completing the rotor depth measuring procedure, or the flush-by service, the slider tool 72 may be used to raise the polished rod 34, together with the attached rod string 44 and rotor 52, to a desired level, allowing the polished rod 34 to be secured at that level by reattaching the polished rod clamp 42. With the polished rod 34 secured at the desired level, the slider tool 72 may then be disconnected from the polished rod 34, and stowed away until the next time the rotor depth may need to be checked, or the flush-by service may need to be performed.
Referring now to
It is contemplated that the polished rod 34 and/or the slider tool 72 may be provided as a kit for retrofitting a conventional progressing cavity pump, or for building a new progressing cavity pump 10 according to an embodiment of the present invention. Furthermore, the kit may include one or more of the polished rod clamp 42, the extended bolts 80, the extended nuts 80, and the indicator 84.
Having described preferred embodiments of the progressing cavity pump 10 above, a method of flushing out debris that has built up in the progressing cavity pump 10 is described next, by way of an example. According to an embodiment of the present invention one method of flushing the progressing cavity pump may follow substantially the following steps:
According to an embodiment of the present invention a method of checking and adjusting the depth of the rotor 52 in the progressing cavity pump 10 may follow substantially the same method as above, but without carrying out the step of flushing the production tubing 16 with a desired fluid (i.e. oil) to free debris build up in the stator 50.
As mentioned above, a conventional progressing cavity pump may also be retrofitted with a polished rod according to the present invention, to convert it into a progressing cavity pump 10 according to the present invention. By way of example, one such method may follow substantially the following steps:
It should be noted that the above method for replacing a conventional polished rod 62 in a conventional progressing cavity pump with a polished rod 34 according to the present invention, does not include steps for setting the rotor 52 to the correct depth. Preferably, however, the rotor 52 may be checked and adjusted using the slider tool 72, prior to the step of filling the production tubing 16 with desired fluid (i.e. oil) and pressure testing the production tubing 16, as described above.
While reference has been made to various preferred embodiments of the invention other variations, implementations, modifications, alterations and embodiments are comprehended by the broad scope of the appended claims. Some of these have been discussed in detail in this specification and others will be apparent to those skilled in the art. Those of ordinary skill in the art having access to the teachings herein will recognize these additional variations, implementations, modifications, alterations and embodiments, all of which are within the scope of the present invention, which invention is limited only by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2997845 | Mar 2018 | CA | national |
