Patent Grant
12331737
Sucker rods used in reciprocating rod lift applications can use one or more sucker rod guides to guide the sucker rods. The main purpose of a sucker rod guide has been to prevent metal-to-metal contact of sucker rod couplings (i.e., the connection of the sucker rods) with the interior of the production tubing. The couplings and the tubing are typically made of steel, and the guides can help to center the sucker rod string in the production tubing and can distance the rods from the tubing wall. The sucker rod guides have typically been made of a thermoplastic or a thermoset plastic and have been commonly used as a sacrificial component of the system to prevent the premature wear of the tubing's internal surface.
In recent years, new wells are being drilled with more complex wellbore geometries. These new well geometries have required more sucker rod guides to be used. Indeed, the more deviated a well is from vertical equates to an increased need to keep the sucker rod couplings from coming into contact with the tubing.
The increased use of sucker rod guides tied with high flow rate in the wells has created a different problem. The geometry of a sucker rod guide forces flow to go around it, which influences the turbulence generated before and after the guide. Therefore, when the sucker rod guides are in use on a rod string, the guides tend to generate a significant perturbance in the fluid flow in the tubing. The extent of this perturbance varies from geometry to geometry and depends on the flow characteristics of the well.
For example, turbulence can be produced in the fluid as the guide is moved during the pumping cycle (e.g., downstroke and upstroke). The change in flow characteristics in the periphery of the sucker rod guides generates several issues that lead to failure on the surface of the sucker rod. When the flow velocity is too high, the fluid will remove any corrosion deposits and accelerate localized corrosion. In other instances, the flow can be stagnant, preventing a corrosion inhibitor from forming a film to protect the sucker rod from corrosion. The corrosion in the area is evidenced as corrosion pits (localized depressions) or corrosion-erosion (widespread depression). These two types of imperfections will act as stress risers due to the fatigue load (axial and bending) to which the rod section is exposed, leading to a crack initiation and posterior sucker rod failure.
Rod guides typically have one or more flutes or channels, which are intended to allow the fluid to pass the guide. The flutes or channels are typically shaped to reduce the disruption of the fluid flow. Several shapes have been developed over the years, and many shapes seek to reduce damaging effects of turbulence by diminishing turbulence generated by the guide or by diminishing the drag force generated by the fluid.
An example of a low turbulence rod guide is disclosed in U.S. Pat. No. 5,115,863, which describes a guide offering minimum cross-section and turbulence without loss of erodible volume. The guide is described as being very long in relation to its diameter to facilitate laminar flow and a low drag coefficient.
Another rod guide is disclosed in U.S. Pat. No. 5,358,041, which describes a rod guide having blades with knife ends to reduce resistance to fluid flow about and through the rod guide and to reduce turbulent flow behind each blade. Yet another example of a rod guide is disclosed in U.S. Pat. No. 9,926,754, which describes a rod guide having a body with a polygonal cross-section and having a plurality of blades longitudinally disposed and extending from the body.
Although existing rod guides may be effective in preventing metal-to-metal contact and even in reducing turbulence, failures to sucker rods may still occur when some sucker rod guides of the prior art are used. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
Some implementations disclosed herein relate to an apparatus or system for a sucker rod used to lift fluid in production tubing, including a guide for use on the sucker rod. In one implementation, the guide includes a body configured to be positioned on the sucker rod, featuring an external surface, first and second body ends, and a first diameter. Additionally, the guide includes a plurality of vanes disposed around the body's external surface, extending radially outward to a second diameter, which is larger than the first diameter. Each vane is symmetrical about both a longitudinal line of symmetry and a lateral line of symmetry, which is at the midpoint of the longitudinal line. These vanes have adjacent sidewalls at each vane end, and the adjacent sidewalls diverge from each other from the vane end and extend to the lateral line of symmetry at the midpoint.
Moreover, the guide defines troughs with sides formed by the sidewalls of adjacent vanes. The sides of each trough near the first body end converge from the vane ends of adjacent vanes to a liminal constriction at the midpoint and then diverge directly from this constriction to the vane ends of the adjacent vanes towards the second body end.
The described implementations may also include one or more of the following features. The guide's body may comprise a sleeve defining a throughbore along a longitudinal axis and configured for positioning on the sucker rod. Each vane end may include a first transition from the external surface. Each vane may have angled faces, positioned between the adjacent sidewalls and extending from the first transition at the vane end to a second transition on the vane, each angled face at an acute angle relative to the longitudinal line of symmetry. Each vane may also include an external face between the adjacent sidewalls, extending along the longitudinal line of symmetry. These external faces define a radius of curvature relative to the longitudinal line of symmetry. The adjacent sidewalls on each vane diverge at an acute angle and extend parallel to a radial line of symmetry. The first diameter of the body increases from both the first and second body ends to the lateral line of symmetry at the midpoint, where each trough has a base defined by the first diameter, converging from the vane ends of adjacent vanes to a liminal waist at the midpoint and diverging to the vane ends of adjacent vanes towards the second body end. The sucker rod is disposed on one or more sucker rods.
In another implementation, the guide includes a sleeve, which has sleeve ends, an external surface, a first longitudinal length, and a first diameter. A plurality of vanes symmetrically is arranged about the sleeve's external surface and extend radially outward to a second diameter. Each vane is symmetrical about a longitudinal line of symmetry and a lateral line of symmetry.
The vane ends are separated by a second longitudinal length less than the first longitudinal length. The vane ends have a first transition from the external surface, adjacent sidewalls diverging at a first angle, and angled faces between the sidewalls extending at a second angle from the first transition.
The vane includes an external face disposed between the sidewalls and extends along the longitudinal axis. Troughs with sides are formed by the sidewalls of adjacent vanes. These troughs converge towards the first body end from the vane ends to a constriction at the midpoint and then diverges towards the second body end.
The described implementation may also include one or more of the following features. The adjacent sidewalls for each vane can extend parallel to a radial line of symmetry. The external faces can define a radius of curvature relative to the longitudinal axis. The first and second angles can be defined in specified ranges. For example, the first angle can be in a range of 10 to 15 degrees, and the second angle can be in a range of 20 to 25 degrees. The vanes can be disposed at 90 degrees about the longitudinal axis.
The first diameter of the sleeve can increase from the sleeve ends at a third angle to the lateral line of symmetry. The third angle can be in a range of 1 to 5 degrees. Each trough base can converge from the vane ends to a waist at the midpoint and can diverge towards the second body end. The third angle can also be within a specific range.
Each external face of the vanes can have a diamond shape. The sleeve ends can define a third transition to the first diameter, and both the first and second transitions can be curved. The sleeve and vanes can be made of materials, such as polymeric material, thermoplastic elastomer, thermoset resin, polyurethane, polyamide, composite material, or metallic material. The sleeve can include a throughbore for positioning on the sucker rod.
In yet another implementation, a sucker rod string used to lift fluid in production tubing comprises one or more sucker rods being configured to connect together and comprises one or more guides disclosed above and disposed on the one or more sucker rods.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.
The present disclosure is directed to guides for sucker rods used for pump systems, such as sucker rod pumps or progressive cavity pumps, which extract fluids from a well and employ a downhole pump connected to a driving source at the surface. For example,
For instance, the downhole pump 14 has a barrel 16 with a standing valve 24 located at the bottom. The standing valve 24 allows fluid to enter from the wellbore, but does not allow the fluid to leave. Inside the pump barrel 16, a plunger 20 has a traveling valve 22, which allows fluid to move from below the plunger 20 to the production tubing 18 above, but does not allow fluid to return from the tubing 18 to the pump barrel 16 below the plunger 20.
The driving source (e.g., a pump jack or pumping unit 26) at the surface connects by the rod string 12 to the plunger 20 and moves the plunger 20 up and down cyclically in upstrokes and downstrokes to lift fluid to the surface. As shown in
A detail of a sucker rod guide 100 according to the present disclosure is depicted in
The sucker rod guide 100 may be molded onto the sucker rod 30 or may be fitted with an axial slot for installation on the rod 30 in the field. The guide 100 may be retrofitted onto or used with a conventional sucker rod 30. Alternatively, the guide 100 may be used on a dedicated rod or rod section, which may be as long as or shorter than a conventional sucker rod 30.
Vanes 110 on the guide 100 extend in the annular space between the sucker rod 30 and the production tubing 18. As the sucker rod 30 is reciprocated, the guide 100 can act as a circumferential bushing and centralizer that centers the rod string 12 in the production tubing 18. The guide 100 serves as a sacrificial component for riding along the tubing 18 and preventing metal-to-metal contact of the sucker rods 30 and couplings 40 against the tubing 18.
During an upstroke, the fluid column F in the annulus of the production tubing 18 is moved uphole in the tubing 18 as the rod string 12 is lifted. The guide 100 may move together with the lifted fluid column F, as both are lifted during the stroke of the pump jack 26. At the end of the upstroke, the lifted fluid column F stays in place in the production tubing 18. Then, during the down stroke, the rod string 12 and the guide 100 are moved downhole through the fluid column F. In general, the flow velocity of the fluid and the velocity of the sucker rod guide 100 are not necessarily related. In reality, these two velocities can become markedly independent of one another. In a shallow well, for example, a sort of pulsating effect can be produced. In a deeper well, any pulsation may be almost imperceptible.
As the guide 100 moves downhole through the fluid column F, the length of the guide 100 from the downhole end 101d toward the uphole end 101u disrupts the stationary fluid in the fluid column F, producing differences between higher and lower pressure zones, causing the fluid to flow relative to the guide 100, and producing turbulence especially toward the uphole end 101u of the guide 100. The increase in fluid velocity can cause fluid erosion of the sucker rod 30, and low-pressure zones can cause erosion-corrosion and CO2 breakout. The sucker rod guide 100 of the present disclosure is directed to reducing turbulence to mitigate detrimental effects to the sucker rod 30.
As discussed in more detail below, the disclosed sucker rod guide 100 acts as a guard to protect both the sucker rod 30 and the tubing 18—i.e., protecting the tubing's internal surface and protecting the sucker rod body at the periphery of the guide 100. The configuration of the disclosed sucker rod guide 100 pushes the wake of turbulence off from the periphery of the sucker rod guide's ends, without sacrificing the erodible wear volume to be safely worn in protecting the tubing surface as well.
The configuration of the disclosed sucker rod guide 100 has been evaluated utilizing computational flow dynamics simulation software with a special emphasis on the turbulence intensity [%] value and behavior at the edge of the geometry and on the surface of the sucker rod. This configuration of the disclosed sucker rod guide 100 accelerates the flow in the middle of the geometry and generates a smooth deceleration at the ends. The configuration produces flow with a reduced separation in the boundary layer around the whole volume of the guide's geometry, and the configuration allows different velocity flow streams to reconnect with one another before leaving the sucker rod guard's geometry. The resulting flow produced by the guide 100 reduces the impact on the sucker rod body at the periphery of the guide 100.
The body 102, which can be a sleeve, is configured to position on the sucker rod 30. The body or sleeve 102 has ends 104a-b, and an external surface 106. The vanes are disposed symmetrically about the external surface 106 of the sleeve 102 and extend radially outward. Each of the vanes 110 has vane ends 111a-b, adjacent sidewalls 120a-b, angled faces 130, and an external face 140. At each vane end 111a-b, each vane 110 transitions with a first transition 112 from the sleeve's external surface 106. The adjacent sidewalls 120a-b at each of the vane ends 111a-b diverge from one another starting at the first transition 112 and extend to a middle section of the sleeve 102. At each vane end 111a-b, each angled face disposed between the adjacent sidewalls 120a-b extends from the first transition 112 outward from the sleeve's external surface 106 to a second transition 114. Finally, the external face of each vane 110 disposed between the adjacent sidewalls 120a-b extends between the second transitions 114.
Further details of the guide 100 are illustrated in
The sleeve as shown in
As further shown in
The vane ends 111a-b of the vanes 110 at the first transitions 112 are separated by a second longitudinal length L2, which is less than the first longitudinal length L1.
The adjacent sidewalls 120a-b on the vanes 110 diverge from one another at a first angle (a). The adjacent sidewalls 120a-b extend from the first transitions 112 to the lateral line of symmetry (LLS) at the midpoint of the longitudinal line of symmetry (LLS). As a result, the vanes 110 have a diamond shape with pointed ends and with a width W1 at their midpoints.
As shown in
As shown in
As shown in
As best shown in the cross-section of
Turing now to
As noted, each of the vanes 110 is symmetrical about a longitudinal line of symmetry, and each of the vanes 110 is symmetrical about a lateral line of symmetry at a midpoint of the longitudinal line of symmetry. Each of the vanes 110 has adjacent sidewalls 120a-b at each vane end 111a-b of each vane 110.
Each trough 150 has sides 152, 154 formed by the sidewalls 120a-b of adjacent ones of the vanes 110a-b. The sides 152, 154 of the trough 150 toward the first body end 104a converge from the first of the vane ends 111a of the adjacent vanes 110a-b to a liminal constriction 155 at the midpoint (of lateral symmetry). The sides 152, 154 of the trough 150 then diverge directly from the liminal constriction 155 to the second of the vane ends 111b of the adjacent vanes 110a-b toward the second body end 104b.
As further noted, the diameter of the body 102 increases from each body end 104a-b to the lateral line of symmetry at the midpoint. Accordingly, the trough 150 has a base 156 defined by the diameter of the body 102. The base 156 toward the first body end 104a converges at least from the first the vane ends 111a of the adjacent vanes 110a-b to a liminal waist 157 at the midpoint and diverges directly from the liminal waist 157 at least to the second of the vane ends 111b of the adjacent vanes 110a-b toward the second body end 104b.
The configuration disclosed above controls the flow of fluid along the guide 100 to provide the benefits described herein. As discussed herein, the fluid flow is rearranged in the wake of the guide 100 to reduce the risk of localized corrosion to the sucker rod surface at the periphery of the sucker rod guide.
Certain dimensions of the guide 100 depend on the type of sucker rod for which it is used and the size of the production tubing in which it is installed. In that regard, the tubing sizes most commonly used for rod-pumped wells include: 2-38 inches, 2⅞ inches, 3½ inches, and 4½ inches, which are selected based on factors such as well depth, production rate, and the specific conditions of the reservoir. Meanwhile, the sucker rod can have a diameter from ⅝ inch to more than 1 or 1¼ inches. Accordingly, as one example, a sucker rod with a ⅞-inch diameter may be used in production tubing having an outside diameter of 2⅞ inches so that the sizing of the disclosed guide 100 would be configured for use with these and other dimensions.
For example,
As can be seen here, the overall lengths of the guides can be consistent with one another in these examples. The outer diameters D2 of the guides 100 are consistent for the same OD tubing sizes. For example, the guides 100 in
In general, the length L1 of the sleeve 102 can have sizes of about 5 inches to about 12 inches. The diameter D1 of the sleeve 102 can be about 0.625 inches to 1.750 inches. With respect to these sizes, the lengths L2 of the vanes are less than L1 and can be about 4 inches to 11 inches. The outer diameter D2 of the guide 100 at the external faces 140 of the vanes 110 can have sizes of about 1 inch to 3.5 inches.
For one implementation of the guide 100, the first angle (a) can be an acute angle of about 10 to 15 degrees, and the second angle (B) can be an acute angle of about 20 to 25 degrees. The third angle (x) can be an acute angle of about 1 to 5 degrees.
Because the guide 100 is used downhole in production tubing, the external faces 140 on the vanes 110 of the guide 100 are configured to provide a suitable sweep perimeter. In general, given as a percentage of 360-degree coverage, the sweep perimeter can be about 50%.
Additionally, the guide's geometry and symmetrical configuration noted above seeks to reduce turbulence intensity in the transition between guide 100 and rod body. It is believed that the disclosed geometry and configuration can produce a ten-fold improvement compared to typical guides.
As discussed in the background of the present disclosure, for instance, failure analysis shows that the flow around a convention sucker rod guide can produce a significant number of rod failures at the periphery of the guide. Evaluations have identified erosion-corrosion patterns in failure samples and use Computational fluid dynamics (CFD) to assist in the validation and posterior solution design. CFD analysis has produced quantitative predictions of fluid-flow phenomena based on the conservation laws (conservation of mass, momentum, and energy) governing fluid motion.
Using CFD evaluation, the geometry and symmetrical configuration of the guide 100 disclosed herein has been developed to minimize the turbulence and the appearance of vortexes at the edges of the guide 100. Particular emphasis has been made to reduce turbulent events from the transition of the guide 100 to the rod body.
As noted previously, failure analysis shows that sucker rod body failures in the periphery of the sucker rod guides are typically associated with these main factors: corrosion-erosion, corrosion-fatigue, and excessive bending. Flow analysis to improve the design of the disclosed guides has taken parameters into account, which include reducing turbulence (turbulent intensity and kinetic energy) downstream of the guide and focusing on the transition of the flow conditions of the guide end to the rod-surface.
Some details of fluid analysis for the guide 100 disclosed herein are illustrated with reference to
In general, the turbulence intensity is a ratio of (i) the Root-Mean-Square (RMS) or Standard Deviation of the turbulent velocity fluctuations at a particular location over a specified period of time relative to (ii) the average of the velocity at the same location over same time period. Turbulence intensity above 100% means that the velocity fluctuations at the outlet have velocity changes/fluctuations in the order of the mean velocity. Turbulence intensity of 20% or above could be considered high for some applications.
Viewed from the side,
As a further illustration,
Based on the specifics discussed above, the disclosed sucker rod guide 100 can distribute/arrange/direct/control fluid flow to prevent turbulence outbreaks around the rod's periphery. In particular, the geometric configuration of the guide 100 facilitates fluid flow rearrangement in the wake of the guide 100. The guide 100 can reduce the risk of localized corrosion to the sucker rod surface in the periphery of the sucker rod guide. This is evidenced by the use of CFD, which indicates the turbulence intensity percentage at that region with a percentage below about 30%. This is at least ten times smaller than the turbulence intensity generated by other conventional sucker rod guides.
The guide 100 provides a wide sweep length/angle without requiring flow twisting, which is a departure from conventional slant geometries employed in conventional sucker rod guides. The geometric configuration of the guide 100 can enhance paraffin scraping capabilities and can promote improved contact sweep, which can be particularly beneficial for integrating self-lubricant additives in polymers such as silicon, graphite, moly, and Teflon.
Additionally, the dimensions of the guide, such as its length and tapered ends, play a role in distributing bending moments across the rod body edge, ensuring structural integrity and stability. For example, the guide's localized center of mass reduces stiffness at the ends, minimizing bending moment-induced stresses and extending bending support to the rod. The guide's thicker transition further enhances structural integrity and provides a reliable seal. Moreover, the guide's configuration seeks to optimize the contact area between the rod and guide, thereby maximizing detachment. This can be beneficial in environments having high side loads, mitigating the risk of premature stripping of fiber materials downhole.
Finally, the disclosed guide 100 aims to deliver an Equivalent Wear Volume (EWV) compared to conventional guides and can provide consistent performance and reliability in sucker rod applications. The guide 100 can incorporate wear gauge indications to monitor even wear distribution, particularly crucial when utilized on a rod rotator. While some guides may exhibit uneven wear patterns, the gauge serves as a reference point for maintenance and performance assessment.
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.
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| Entry |
|---|
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