US20090183885A1

US20090183885A1 - Rod guide with improved stator

Info

Publication number: US20090183885A1
Application number: US12/009,892
Authority: US
Inventors: Matthew S. Davison
Original assignee: Robbins and Myers Energy Systems LP
Current assignee: Robbins and Myers Energy Systems LP
Priority date: 2008-01-23
Filing date: 2008-01-23
Publication date: 2009-07-23
Also published as: WO2009094139A1; AR070226A1

Abstract

A rod guide is provided for use in a rotating rod string (12) for powering a progressive cavity pump (14) for pumping downhole fluids through tubing string (16) to the surface. The rod guide includes a rotor sleeve (20) secured to the rod string. A stator sleeve (40) is positioned over the rotor sleeve, and has a sleeve body (42) with a generally circular configuration with opposing circumferential ends (44, 46) spreadable to position the stator sleeve about the rotor sleeve. A plurality of ribs (48) extend outward from the stator sleeve body. One circumferential end of the stator sleeve has a catch member (52), and an opposing circumferential end of the stator sleeve has a receiving cavity (54) for receiving at least a portion of the catch member. The circumferential ends of the stator sleeve are connected by the catch member and the receiving cavity.

Description

FIELD OF THE INVENTION

The present invention relates to a rod guide of a type suitable for guiding a sucker rod within production tubing of an oil or gas well. More particularly, the invention relates to a rod guide for guiding a rotary sucker rod which powers a progressive cavity (PC) pump in a well.

BACKGROUND OF THE INVENTION

Various types of rod guides have been devised for guiding a sucker within production tubing. Many rod guides are intended for use with a reciprocating sucker rod, and other rod guides are primarily intended for use with a rotating sucker rod. Some guides have utility for either a reciprocating rod or a rotating rod, although design considerations generally dictate that a sucker rod guide be primarily intended for one application.
Compared to commonly used beam pumps which are powered by a reciprocating sucker rod, progressive cavity pumps are generally able to deal with a high concentration of sand or other particulate in the recovered fluid. In many cases, however, rod guides for PC pumps wear excessively when subjected to the upwardly moving fluid and sand within the production tubing. The cost of replacing PC rod guides for these applications thus represents a significant cost to the well operator. Other rod guides have low erodeable wear volume, i.e., the volume of the guide radially exterior of the rod coupling is minimal, and wear of that excess material reduces the purpose of the guide. Other rod guides have poor flow characteristics, meaning that the flow channels around the guide result in a high pressure loss, thereby increasing the power required to pump the fluids to the surface. Other types of rod guides allow sand or other particles to become trapped or imbedded between components of the guide, thereby substantially contributing to premature wear of the guide.
Many rod guides designed for PC pumps include a rotor sleeve secured to the rod string and a stator sleeve positioned about the rotor sleeve. The stator sleeve conventionally has an elongate slot, which is spread apart to position the stator sleeve on the rotor sleeve. The slot facilitates installation, but also allows sand and other debris from the well to get trapped between the rotor sleeve and the stator sleeve. Also, the rod guide rotor sleeve with a conventional slot may have problems when used in high temperature downhole applications, since the stator sleeve may tend to open when exposed to high temperature.
The disadvantages of the prior art are overcome by the present invention, and an improved rod guide particularly suited for a progressive cavity pump is hereinafter disclosed.

SUMMARY OF THE INVENTION

In one embodiment, a rod guide for positioning on a rotating sucker rod which powers a downhole progressive cavity pump for pumping downhole fluids to the surface includes a rotor sleeve secured to the rod, and a stator sleeve positioned about the rotor sleeve. The stator sleeve has a sleeve body with a generally circular configuration with opposing circumferential ends spreadable to position the stator sleeve about the rotor sleeve. The stator sleeve has a plurality of ribs extending outward from the sleeve body for passing fluid between the stator sleeve body and tubing and circumferentially between the two or more ribs. One circumferential end of the stator has a catch member, and an opposing circumferential end of the stator sleeve has a receiving cavity for receiving at least a portion of the catch member. The circumferential ends of the stator sleeve are connected via the catch member and the receiving cavity.
According to one embodiment of the method of the invention, the rotor sleeve is secured to the sucker rod, and the stator sleeve positioned about the rotor sleeve. The stator sleeve has a sleeve body with a generally circular configuration with opposing circumferential ends separable to position the stator sleeve about the rotor sleeve, and has a plurality of ribs extending outward from the sleeve body. The method includes providing one circumferential end of the stator sleeve with a catch member and an opposing circumferential end of the stator sleeve with a receiving cavity for receiving at least a portion of the catch member. The circumferential ends of the stator sleeve are connected about the rotor sleeve by mating the catch member and the receiving cavity.
It is a feature of the invention to provide a rod guide for powering a progressive cavity pump, wherein one circumferential end of the stator sleeve includes a catch member and an opposing circumferential end of the stator sleeve includes a receiving cavity for receiving at least a portion of the catch member. A significant advantage of the present invention is that by connecting the ends of the stator sleeve, little or no sand or other debris is allowed to pass radially through the stator sleeve and in the cavities between the rotor sleeve and the stator sleeve.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a rod guide stator sleeve according to the present invention.

FIG. 2 is a cross sectional view of the rod guide stator sleeve shown in FIG. 1.

FIG. 3 is an enlarged view of the ends of the stator sleeve as shown in FIG. 2.

FIG. 4 in enlarged view of an alternate embodiment of the circumferential ends of the stator sleeve.

FIG. 5 illustrates the rod guide stator sleeve shown in FIG. 1 positioned on a rod guide rotor and the circumferential ends of the stator sleeve connected.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates one embodiment of a stator sleeve 40 according to the present invention. A rod guide as disclosed herein is particularly suitable for use in a rotating rod string 12 which powers a progressive cavity (PC) pump 14, as shown in FIG. 5. The rod string 12 rotates to drive the pump 14, and fluid is pumped upward through a tubular string 16 and past the rod guides to the surface. The rod guide itself includes a rotor sleeve 20 which is secured to a rod 12, and a stator sleeve 40, which is positioned about the rotor sleeve. The stator sleeve effectively guides the rod string within the tubular string to prevent excessive wear on the tubular string, and the stator sleeve either does not rotate or rotates intermittently with a rotor, often at a much lower rpm.
Referring to FIG. 5, the rod guide is shown with a sleeve shaped rotor sleeve 20 which is molded or otherwise secured to the rotating rod string 12. The rod guide is positioned within the interior of the production tubing string 16, and the rotating rod powers a progressive cavity pump 14 schematically shown at the lower end of the rod string 12 in FIG. 1. The rotor sleeve 20 is fairly conventional for a PC application, and comprises a substantially sleeve shaped body 22 and upper stop member 24 with a lower stop surface 26, a lower stop member 28 with an upper stop surface 30. The exterior surface 32 of the stator sleeve may have a generally cylindrical configuration, thereby prolonging the life of the rod guide as the rod string and the rotor sleeve rotate within the stator sleeve.
Referring again to FIG. 1, a side view of the rotor sleeve 40 illustrates a generally sleeve shaped body 42 and a plurality of ribs 60. Typically, three or more ribs 60 extend radially outward from the sleeve shaped body 42. The outer surfaces 62 of ribs 60 are thus the surfaces which engage the interior of the production tubing string during use of the rod guide. Fluid thus flows between the sleeve shaped body 42 and the interior of the production tubing, and circumferentially between the ribs 60. The upper and lower ends of each rib 60 may include a tapered section 64 which taper inward to the extremity of the stator sleeve to substantially coincide with the exterior surface of the sleeve shaped body 42.
FIG. 2 illustrates in further detail of the stator sleeve as shown in FIG. 1, with one circumferential end 44 of the stator body 42 including a catch member 52, and an opposing circumferential end 46 of the body 42 including a receiving cavity 54 for receiving at least a portion of the catch member 52. When the stator sleeve is positioned about the rotor sleeve, the circumferential ends of the stator sleeve may be brought into mating engagement, with catch member 52 entering the receiving cavity 54 effectively connecting the ends of the body 42 together. This feature not only desirably maintains the stator sleeve on the rotor sleeve during use, it also substantially reduces if not eliminates migration of sand and other particles radially inward between the rotor sleeve and the stator sleeve.
FIG. 3 depicts an enlarged view of the circumferential ends of the stator sleeve when brought together. Throat 56 for the receiving cavity 54 has a cavity entrance portion 64 which is wider than the neck portion 66, thereby tending to properly position the catch member 52 within the receiving cavity. Since the radial width of the catch member 52 is greater than the radial width of the neck portion 66, the catch member 52 once latched is designed to stay in the closed position. Surface 68 on the catch member is thus a planar surface which is substantially parallel to the axis of the rotor, and engages a similar planar surface 70 on the sleeve body adjacent the receiving cavity, thereby retaining the components connected together and maintaining the stator sleeve connected at its circumferential ends.
FIG. 4 depicts an alternate embodiment of the circumferential ends 44, 46 of the rotor sleeve. In this case, the catch member 72 on the end 44 of the stator sleeve has a substantially ball-shaped configuration, and the receiving cavity 74 in the opposing end 56 of the stator sleeve similarly has a generally circular cross section. A throat 78 is narrower than the diameter of the ball member 72, and accordingly is spread slightly apart when the ball is forced into the receiving cavity. This design applies a substantial holding force to retain the two circumferential ends of the stator sleeve together, but does allow the catch member to be removed from the cavity by applying a circumferential spreading force, thereby allowing the stator sleeve to be removed from the rotor sleeve, then reinstalled on the same rotor sleeve or another rotor sleeve.
A significant feature of the present invention is that the catch member and the receiving cavity are provided axially along substantially the length of the stator sleeve. Thus, the catch member 52 and the cavity 54 as shown in FIG. 4 are each substantially a vertical column, and similarly the catch member 72 and the receiving cavity 76 are vertical columns. By providing the catch member and the receiving member along substantially the entire length of the stator sleeve, the forces to hold the stator sleeve together on the rotor sleeve are increased. Moreover, this engagement substantially minimizes the likelihood of sand and other debris moving radially between the stator sleeve and the rotor sleeve, which was a problem with prior art rod guides which had an open slot when the stator sleeve was positioned on the rotor sleeve. While sand or other debris may pass between the ends of the stator sleeve and the respective stop surfaces 26, 28, as shown in FIG. 1, most of the high wear experienced on PC rod guides is not attributable to debris entering the rod guide at these locations, but rather occurs as sand and other debris move radially inward through the slot in the stator sleeve to engage the rotor sleeve, then becomes trapped between the stator sleeve and the rotor sleeve.
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.

Claims

1. A rod guide for positioning on a rotating sucker rod for powering a progressive cavity pump for pumping downhole fluids, the rod guide comprising:

a rotor sleeve secured to the sucker rod;

a stator sleeve positioned over the rotor sleeve, the stator sleeve having a sleeve body with a generally circular cross sectional configuration and opposing circumferential ends spreadable to position the stator sleeve about the rotor sleeve, the stator sleeve having a plurality of ribs extending outward from the sleeve body for passing fluid between the stator sleeve body and production tubing and circumferentially between the plurality of ribs;

the rotor sleeve including upper and lower stop surfaces for limiting axial movement of the stator sleeve relative to the rotor sleeve; and

one circumferential end of the stator sleeve body having a catch member and an opposing circumferential end of the stator sleeve body having a receiving cavity for receiving at least a portion of the catch member, such that the circumferential ends of the stator sleeve body define a circumferential gap held closed by connecting the catch member and the receiving cavity.

2. A rod guide as defined in claim 1, wherein the catch member and the receiving cavity are configured to repeatedly connect and disconnect the circumferential ends of the stator sleeve body.

3. A rod guide as defined in claim 1, wherein each of the catch member and the receiving member is positioned radially between a radially inner generally cylindrical surface of the stator sleeve body and a radially outer generally cylindrical surface of the stator sleeve body.

4. A catch member as defined in claim 1, wherein each of the catch member and the receiving cavity has a substantially rectilinear configuration.

5. A rod guide as defined in claim 1, wherein each of the catch member and the receiving cavity has a substantially ball-shaped configuration.

6. A rod guide as defined in claim 1, wherein the rotor sleeve is molded on the sucker guide.

7-8. (canceled)

9. A rod guide as defined in claim 1, wherein the receiving cavity has an entrance throat with a narrowing neck portion for guiding the catch member within the receiving cavity.

10. A rod guide as defined in claim 1, wherein the catch member and receiving cavity are provided along substantially the entirety of an axial length of the stator sleeve body.

11. A rod guide as defined in claim 1, wherein the circumferential ends of the stator sleeve body substantially seal an interior of the stator sleeve from fluids radially exterior of the stator sleeve body.

12. A rod guide for positioning on a rotating sucker rod for powering a progressive cavity pump for pumping downhole fluids, the rod guide comprising:

a rotor sleeve secured to the sucker rod, the rotor sleeve including one or more stop surfaces for limiting axial movement of a stator sleeve relative to the rotor sleeve;

the stator sleeve positioned over the rotor sleeve, the stator sleeve having a sleeve body with a generally circular cross sectional configuration and opposing circumferential ends spreadable to position the stator sleeve about the rotor sleeve, the stator sleeve having a plurality of ribs extending outward from the sleeve body for passing fluid between the stator sleeve body and production tubing and circumferentially between the plurality of ribs;

one circumferential end of the stator sleeve body having a catch member and an opposing circumferential end of the stator sleeve body having a receiving cavity for receiving at least a portion of the catch member, such that the circumferential ends of the stator sleeve body define a circumferential gap held closed by connecting the catch member and the receiving cavity; and

each of the catch member and the receiving member is positioned radially between a radially inner surface of the stator sleeve body and a radially outer surface of the stator sleeve body.

13. A rod guide as defined in claim 12, wherein the rotor sleeve is molded on the sucker guide.

14. A rod guide as defined in claim 12, wherein the receiving cavity has an entrance throat with a narrowing neck portion for guiding the catch member within the receiving cavity.

15. A rod guide as defined in claim 12, wherein the catch member and receiving cavity are provided along substantially the entirety of an axial length of the stator sleeve body.

16. A method of providing a rod guide on a rotating sucker rod for powering a progressive cavity pump for pumping downhole fluids, the method comprising:

securing a rotor sleeve to the sucker rod;

positioning a stator sleeve over the rotor sleeve, the stator sleeve having a sleeve body with a generally circular configuration with opposing circumferential ends spreadable to position the stator sleeve about the rotor sleeve, the stator sleeve having a plurality of ribs extending outward from the stator sleeve body for passing fluid between the stator sleeve body and production tubing and circumferentially between the plurality of ribs; and

providing one circumferential end of the stator sleeve body with a catch member and an opposing circumferential end of the stator sleeve body with a receiving cavity for receiving at least a portion of the catch member; and

connecting the circumferential ends of the stator sleeve body about the rotor sleeve by closing a circumferential gap between the circumferential ends of the stator sleeve body and connecting the catch member and the receiving cavity.

17. A method as defined in claim 16, further comprising:

positioning each of the catch member and the receiving member radially between a radially inner surface of the stator sleeve body and a radially outer surface of the stator sleeve body.

18. A method as defined in claim 16, further comprising:

positioning one or more stop surfaces on the rotor sleeve for limiting axial movement of the stator sleeve relative to the rotor sleeve.

19. A method as defined in claim 16, further comprising:

providing the catch member and receiving cavity along substantially the entirety of an axial length of the stator sleeve body.

20. A method as defined in claim 16, wherein the circumferential ends of the stator sleeve body substantially seal an interior of the stator sleeve body from fluids radially exterior of the stator sleeve body.