Patent Application
20240247653
The subject matter of the present disclosure is generally directed to a reciprocating pump unit and more particularly directed to a horsehead that is lightweight and has a lattice structure to reduce weight at the front end of the pumping unit for more efficient operation without sacrificing structural integrity.
Reciprocating pump systems, such as sucker rod pump systems, extract fluids from a well and employ a downhole pump connected to a driving source at the surface. A rod string connects the surface driving force to the downhole pump in the well. When operated, the driving source cyclically raises and lowers the downhole pump, and with each stroke, the downhole pump lifts well fluids toward the surface.
For example,
During the upstroke, the traveling valve 22 is closed, and any fluid above the plunger 20 in the production tubing 18 is lifted towards the surface. Meanwhile, the standing valve 24 opens and allows fluid to enter the pump barrel 16 from the wellbore.
At the top of stroke, the standing valve 24 closes and holds in the fluid that has entered the pump barrel 16. Furthermore, throughout the upstroke, the weight of the fluid in the production tubing 18 is supported by the traveling valve 22 in the plunger 20 and, therefore, also by the rod string 12, which causes the rod string 12 to stretch. During the downstroke, the traveling valve opens, which results in a rapid decrease in the load on the rod string 12. The movement of the plunger 20 from a transfer point to the bottom of stroke is known as the “fluid stroke” and is a measure of the amount of fluid lifted by the pump 14 on each stroke.
At the surface, the pump unit 30 is driven by a prime mover 40, such as an electric motor or internal combustion engine, mounted on a pedestal above a base 32. Typically, a pump controller 36 monitors, controls, and records the pump unit's operation. Structurally, a Samson post 34 on the base 32 provides a fulcrum on which a walking beam 50 is pivotally supported by a saddle bearing assembly 35.
Output from the motor 40 is transmitted to a gearbox 42, which provides low-speed, high-torque rotation of a crankshaft 43. Both ends of the crankshaft 43 rotate crank arms 44 having counterbalance weights 46. Each crank arm 44 is pivotally connected to a pitman arm 48 by a crank pin bearing 45. In turn, the two pitman arms 48 are connected to an equalizer bar 49, which is pivotally connected to the rear end of the walking beam 50 by an equalizer bearing assembly 55.
A horsehead 52 with an arcuate forward face 54 is mounted to the forward end of the walking beam 50. As is typical, the face 54 may have tracks or grooves for carrying a flexible wire rope bridle 56. At its lower end, the bridle 56 terminates with a carrier bar 58, upon which a polished rod 15 is suspended. The polished rod 15 extends through a packing gland or stuffing box at the wellhead 13. The rod string 12 of sucker rods hangs from the polished rod 15 within the tubing string 18 located within the well casing and extends to the downhole pump 14.
The horsehead 60 must be very large to accommodate the longer stroke length created by a large, long stroke pumping unit. The arc length of the front face plate 66 (the runner) is as long as the stroke length of the polished rod 15 plus enough additional length to create sufficient runout. Thus, the arch length of the horsehead 60 must be proportionally large to match the longer the stroke length of the pumping unit 70. Consequently, the size of the horsehead 60 results in significant additional weight to the beam 50.
In the design of a conventional beam pumping unit 10, a goal is to achieve a neutral balance as near as possible between the front and back of the walking beam 50. The neutrally balanced walking beam 50 allows the least amount of counterbalance weight to lift the maximum load, resulting in greater mechanical and electrical efficiency for the pump unit 10.
The majority of horseheads 60 are fabricated from solid plate steel with the sole focus on compliance with API design specifications. For example,
The horsehead 60 is of simple fabrication using solid sides 62a-b and face plate 66, and little consideration is given for handling or installation efficiency. As shown in this example, the horsehead 60 can have side plate cutouts 63b in the sides 62a-b. These cutouts 63b do reduce the weight of the horsehead 60 by a minor amount. However, the cutouts 63b are actually used as a means for saving steel plate material. In particular,
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.
A horsehead is disclosed herein for use on a walking beam of a reciprocating pump unit. The horsehead comprises side plates, a face, a plurality of tabs, and brace plates. The side plates are disposed adjacent to one another with a space therebetween. Each of the side plates has a front edge and a back edge. The face is affixed to the front edges of the side plates and has a top end and a bottom end. The face defines a split therein extending from the bottom end toward the top end. The tabs are affixed to the face across the split. The brace plates are connected in the space between the side plates and are arranged in a lattice structure.
A reciprocating pump unit disclosed herein comprises arms, an equalizer bar, a walking beam, and a horsehead as disclosed above. The arms are configured to translate on the reciprocating pump unit, and the equalizer bar is hingedly connected to the arms. The walking beam is mounted to pivot on the reciprocating pump unit. The horsehead is mounted on the walking beam.
A method is disclosed of fabricating horsehead for use on a walking beam of a reciprocating pump unit. The method comprises, not necessarily in sequence: forming side plates each having a front edge and a back edge; forming a face having a top end and a bottom end, the face defining a split therein extending from the bottom end toward the top end; forming brace plates; affixing the face to the front edges of the side plates; affixing a plurality of tabs to the face across the split; and affixing the brace plates in a lattice structure in a space between the side plates.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.
In general, the pitman arms 48 are configured to translate on the pump unit 30, and the equalizer bar 49 is hingedly connected to the arms 48. The walking beam 50 is mounted to pivot on the pump unit 30, and an equalizer bearing assembly 55 connects the equalizer bar 49 to the walking beam 50.
During operation, for example, the pump unit 30 is driven by a prime mover 40 mounted on a pedestal above a base 32. Structurally, a Samson post 34 on the base 32 provides a fulcrum on which the walking beam 50 is pivotally supported by a saddle bearing assembly 35.
Output from the motor 40 is transmitted to a gearbox 42, which provides low-speed, high-torque rotation of a crankshaft 43. Both ends of the crankshaft 43 rotate crank arms (one crank arm is not shown in
As noted above, the walking beam 50 is preferably balanced (e.g., neutrally balanced or near neutral) between the front and back ends of the walking beam 50. This allows the least amount of counterbalance weight required to lift a maximum load, resulting in greater mechanical and electrical efficiency for the pump unit 30. Given the sheer size that the horsehead 100 needs to be for a long stroke pumping unit, any weight reduction is helpful in achieving the optimal balance. To conform to the required dimensional envelope with the lowest possible weight, the horsehead 100 disclosed herein achieves optimal support using the least amount of material.
Turning to further details of the horsehead 100,
The horsehead 100 includes side plates 110a-b, brace plates 130, a face 140, and a plurality of tabs 148. The side plates 110a-b are spaced adjacent to (parallel to) one another with a space therebetween. (The width of the space can be comparable to the width of the walking beam (50) on which the horsehead 100 mounts.) Each of the side plates 110a-b has a front edge 112 and a back edge 114. Each of the front edges 112 defines an arc for the stroke length of the pumping unit for which the horsehead 100 is used. The side plates 110a-b can define cutouts 116 in the front edge 112, which as noted may only minimally reduce weight but allows the side plates 110a-b to be fabricated from a standard sized sheet of plate material.
The brace plates 130 are connected in the space between the side plates 110a-b and are arranged in a lattice structure. The face 140 is affixed to the front edges 112 of the side plates 110a-b and has a bottom edge or end 141a and a top edge or end 141b. The face 140 defines a split 144 therein extending from the bottom end 141a toward the top end 141b so that the face 140 defines divided runner surfaces 142a-b. The tabs 148 are affixed to the face 140 across the split 144. As shown, the tabs 148 can be intermittently spaced along the split 144.
A mounting bar 120 is connected between the side plates 110a-b and is configured to mount the horsehead 100 to the walking beam (50). Preferably, the mounting bar 120 is a hollow tube having a passage 122. Not only does this reduce weight, but the hollow passage 122 through the mounting bar 120 can be exposed on the opposing sides of the horsehead 100. This allows operators to run a cable through the passage 122 of the mounting bar 120 for lifting and moving the horsehead 100.
As best shown in
As shown, the face 140 is made of plate material. Preferably, the face 140 is comprised of a unitary plate that has been cut to include the split 144 and has been bent to define the arc. The split 144 preferably extends from the bottom end 141a toward the top end 141b, but a portion of the top end 141b is left intact to interconnect the runner surfaces 142a-b of the face 140 separated by the split 144. Although the unitary construction is preferred, the face 140 can be formed in other ways, such as using a plurality of plates affixed together to define the runner surfaces 142a-b, the split 144, and the interconnecting top end 141b. The reciprocating pump unit (30) may use a bridle so the top end 141b of the face 140 can include a fixture 146 configured to connect to the bridle.
As generally shown, one or more of the brace plates 130 can define one or more cutouts 131. Preferably, a number of such cutouts 131 are made in the various brace plates 130 to reduce the weight of the brace plates 130 while maintaining structural integrity.
As best shown in
The sheet of plate material used to fabricate the side plates 110a-b can be composed of a conventional material (e.g., steel) and can have a suitable thickness The sheet of plate material for the face 140 can be similarly composed of conventional material (e.g., steel) and can have a suitable thickness. The sheet of plate material for brace plates 130 can be similarly composed of conventional material (e.g., steel) and can have a suitable thickness.
Fabricating the horsehead 100 can include forming the side plates, the face, brace plates, and other components by cutting, stamping, bending, etc. various sheets of plate or another stock material. Affixing the components together can use welding processes and can be done in an appropriate order allowing the assembly to be achieved.
As disclosed herein, the horsehead 100 has a lightweight, box lattice construction. The horsehead 100 includes an internal bracing system composed of configured brace plates 130 supporting notched side plates 110a-b and split individual face runners 142a-b. All of these components are assembled into a lattice structure possessing the same or greater load bearing capacity of the more common solid plate horseheads seen in the majority of pumping units. Additionally, as opposed to a solid bar, the mounting bar 120 is a hollow tube, which saves additional weight. Furthermore, the mounting bar 120 is positioned to allow it to be used as the pickup point for mounting the horsehead 110 onto the walking beam 50 to allow safer and simpler assembly.
The lightweight, box lattice horsehead 100 provides an efficient means to minimize the weight at the frontend of the beam pumping unit 30, which minimizes the amount of counterbalance weight required to lift a given well load. This contributes to lower energy consumption of the pumping unit 30, which in turn reduces operating costs, increases energy efficiency, and lowers the overall carbon footprint.
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.
