Patent Grant
7854259
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.
Various types of rod guides have been devised for guiding a sucker rod 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 effectiveness 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 stator is typically spaced about a cylindrical body of the rotor, and between upper and lower stop surfaces on the rotor. U.S. Pat. Nos. 5,191,938, 5,339,896, 5,755,284, 5,692,562 and 6,065,537 disclose rod guides for guiding a sucker rod intended for powering a downhole pump to pump fluids to the surface of a well.
The disadvantages of the prior art are overcome by the present invention, and an improved rod guide particularly suited for guiding a sucker rod powering a progressive cavity pump is hereinafter disclosed.
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 and a slot defining 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. The rotor sleeve has a plurality of body portions each having an exterior surface of a reduced diameter, and a plurality of ridge portions each having a substantially cylindrical exterior surface of an enlarged diameter greater than the reduced diameter and generally concentric with the rod string. The stator sleeve has an inner surface defining a plurality of substantially cylindrical enlarged diameter portions each with an inner surface adjacent the exterior surface of a respective ridge portion and a plurality of reduced diameter portions each having a diameter less than the enlarged diameter portions for positioning adjacent an inner surface of a reduced diameter body portion.
According to one embodiment of the method of the invention, the rotor sleeve is secured to the sucker rod, and the stator sleeve is 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 a rotor sleeve with a plurality of substantially cylindrical ridge portions each having a substantially cylindrical exterior surface of an enlarged diameter greater than the reduced diameter of the body portions on the rotor sleeve. The method further includes providing a stator sleeve with an interior surface defining a plurality of substantially cylindrical enlarged diameter portions each with an inner surface adjacent the exterior surface of a respective ridge portion and a plurality of reduced diameter portions each having a diameter less than the enlarged diameter portions for positioning adjacent an inner surface of a reduced diameter body portion.
A feature of the present invention is to provide a rod guide for guiding a sucker rod for powering a progressive cavity pump wherein the rotor is secured to the sucker rod and includes a plurality of upper and lower stop surfaces each at the upper and lower ends of a respective ridge for limiting axial movement of the stator with respect to the rotor. It is a further feature of the present invention to provide a rod guide for a rotating sucker rod with improved wear characteristics.
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.
The rotor sleeve 20 includes a plurality of body portions 22 each having an exterior surface 23 of a reduced diameter, and a plurality of ridge portions 24 each having a substantially cylindrical exterior surface 25 of an enlarged diameter greater than the reduced diameter body portions. Each of these outer surfaces is preferably concentric with the rod string, and each of a plurality of ridge portions 24 is axially adjacent at least one and in many cases an upper and a lower reduced diameter body portion. Each of the ridge portions 24 includes an upper stop surface 26 and a lower stop surface 28, with each stop surface lying within a plane substantially perpendicular to a central axis 21 of the rotor sleeve and thus the rod string 12. The purpose of the stop surfaces is explained below.
For many applications, the rotor sleeve includes three or more body portions and three or more ridge portions. The rotor sleeve also includes at least one end cap 30, 32, and preferably both an upper end cap 30 and a lower end cap 32. Each end cap has a conical outer surface 34 with a central axis aligned with the rod string central axis 21 and an apex spaced from the rotor sleeve. A lower stop surface 36 is formed on the upper end cap 30, and an upper stop surface 38 is formed on the lower end cap 32. These stop surfaces are also preferably perpendicular to the central axis of the rotor.
The stator sleeve 40 includes an interior surface defining a plurality of substantially cylindrical large diameter portions 54 each with an inner surface adjacent an exterior surface of a respective ridge portion, and a plurality of reduced diameter portions 56 each having a diameter less than the enlarged diameter stator portions for positioning adjacent a respective exterior surface of a reduced diameter body portion. While the surfaces 23, 25 on the rotor sleeve and the surfaces 54, 56 on the stator sleeve are each preferably cylindrical surfaces, it is primarily important that the enlarged diameter ridge portions 24 have a cylindrical surface 25, since the rotor sleeve is generally the component of a rotating rod guide which first fails. Since the surface 25 is the largest diameter surface on the rotor sleeve which mates with a sliding surface on the stator sleeve, the surface 25, and preferably the surface 54, are both cylindrical surfaces. It should be understood that the term “diameter” as used herein with regard to these surfaces is not limited to a structure which is cylindrical or even circular configuration. The “diameter” of a body portion or a reduced diameter portion on the stator sleeve is thus the largest diameter of this surface when rotating. In some applications, there may be a benefit to providing one or more recesses or other discontinuities in these wear surfaces.
Referring now to
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.
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|---|---|---|---|
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| 7255165 | Abdo et al. | Aug 2007 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20090183869 A1 | Jul 2009 | US |
