Patent Application
20220349395
The present invention generally relates sucker rod pumps for use in pumping formation fluid from an oil well, and more specifically, relates to a downhole sucker rod pump assembly with a rotor operable to generate a vortex in a pump barrel without imparting torque to the plunger. The vortex displaces formation fluid above a plunger assembly, thereby preventing heavier debris in the formation fluid from settling or lodging between a plunger and barrel boundary, thus extending the practical life of the pump.
A downhole sucker rod pump involves the retrieving formation fluid (e.g., thin oil, thick oil-water mixtures containing particles of sand and rock) from wells at depths exceeding 1,000 ft. Some oil wells initially produce formation fluid in the form of a thin oil and as the well becomes depleted, it may produce a thicker oil that, in many cases, contains particles of sand and rock. However, some oil wells produce viscous sand-containing oil from the beginning of pumping. The particles of sand and stone in the formation fluid are non-ideal and lodge in between a plunger and barrel, which causes irrecoverable linear scoring of a barrel or plunger and requires replacement. To contest the damage done to the barrel or plunger, pumps on the market include a means for generating unidirectional rotation of a plunger with an adapter above the plunger that has a plurality of helical flutes or apertures for producing an intermittent rotation of the plunger during reciprocation of the plunger. However, the rotation of the plunger fails to prevent wear on the plunger; instead, the adapter distributes the wear uniformly around the plunger, producing non-linear abrasions on the plunger surface, yielding helical scoring on either the plunger or the barrel.
A plunger is typically fixedly attached to an adapter, and the adapters may have apertures with a helical inclination. The flow of the formation fluid is initially in a substantially laminar and uniform flow, but when the fluid comes into contact with the adapter, the fluid enters into the apertures, and the cross-sectional area of the fluids space decreases, and the velocity potential of the fluid increases. The increase of velocity potential causes the fluid to exit the adapter in a transient flow and generates a forced-free combined vortex. The vortex is generated above the plunger and adapter, thus preventing fluid debris from settling between the barrel and plunger. The apertures and vortex impart torque on the cage and plunger, causing rotation in a direction opposite to the vortex. Although the vortex may prevent fluid debris from settling, the angular velocities of the vortex are limited because the energy potential of fluids velocity transfers to the entire plunger assembly, and the heavier particles lodge into the boundary. When the plunger rotates with debris in the boundary, a helical gash propagates in the plunger and barrel, allowing the fluid to slip between the boundary rendering the pump inoperable, and replacing the plunger barrel or both is necessary to restore proper function. An assembly or device has yet to provide a simple solution to prevent formation fluid containing particles of sand or rock from penetrating between the barrel and plunger walls without introducing a torque to the system. Improvements to adapters used in existing sucker rod pumping systems to reduce wear on the plunger and barrel mating surface are needed.
The present invention provides an improved downhole suction rod pump assembly (for use with a reciprocating piston pump system) for the extraction of fluids (e.g., crude oil) from a subterranean well. The Suction Rod Pump (SRP) assembly incorporates a device operable to generate a vortex and using such assembly. The downhole Suction Rod Pump (SRP) assembly of the present invention is operable to generate a turbulent flow of oils containing coarse and fine particulates from rock and sand during the pumping of oil from deep wells. The downhole SRP assembly may include a rotor that is freely rotatable about the suction rod. The advantages of the SRP assembly are suitable for incorporation with various pumping systems, including tubing pumps, stationary barrel top anchor rod pumps, stationary barrel bottom anchor rod pumps, traveling-barrel rod pumps, top-and-bottom-anchor rod pumps, ring-valve pumps, three-tube rod pumps, pumps with hollow valve rods, stroke-through pumps, the Farr plunger pump, and all pumps having a vertical rod above said plunger.
The SPR assembly may be mechanically connected to surface equipment of a reciprocating piston pump system, which may include a primer mover for providing driving power to the system and can be an electric motor or a gas engine, a gear reducer (e.g., gearbox) for reducing the high rotational speed of the prime mover to the required speed and increasing the torque available at its slow speed shaft. The mechanical action of the prime mover may be translated by mechanical linkages to a walking beam that moves a polished rod in an up and down reciprocating motion. The polished rod is mechanically connected to the SRP assembly, thereby moving the SRP assembly up and down within the well. A wellhead assembly may contain a stuffing box for sealing the polished rod and pumping tee to lead well fluids into a flow line for storage in a barrel or bin.
The SRP assembly provides downhole equipment, including a rod string comprising a plurality of suction rods that run along the inside the tubing string of the well. The rod string provides the mechanical link between the surface equipment and the SRP assembly. The pump plunger assembly is the moving part of the SRP assembly and directly connects to the rod string and lifts formation fluid in the tubing string to the surface. The plunger assembly includes a traveling valve, a cage, a connecting rod, a collar, at least one rotor, and rotor lock. The traveling valve may be a ball valve, which transitions from an open position on the down stroke of the SRP assembly to a closed position on the upstroke of the SRP assembly. The pump barrel or working barrel (e.g., a cylinder) is a stationary component of the subsurface pump and houses a standing valve (e.g., a ball valve) positioned at or near the distal end of the working barrel. The standing valve may act as a suction valve for the pump through which well fluids enter the pump barrel during the upstroke. During the upstroke, the traveling valve is closed and lifts the collected fluid through the working barrel to the surface.
The present invention may provide a plunger assembly with an exterior diameter sized to fit inside a barrel to form a boundary. Regulatory petroleum agencies or institutes such as the American Petroleum Institute (API) may define the tolerances of the various components and combinations of materials used in SRP assembly. The plunger assembly may have an interior conduit through which oil may transfer to the cage. The cage construction may have a thick wall and a hollow internal conduit with at least one port on an upper surface that is operable to allow excess fluid to provide fluid between the barrel the connecting rod. The cage may have a diameter less than the plunger diameter alleviating the internal pressure in a conduit of the rod string, which is subject to additional forces, as explained below. Typically, a cage may be fastened to a plunger's upper surface. The cage's geometry may be such that fluid leaves the cage ports in a substantially laminar flow and fills the region above the plunger with formation fluid collected from the subterranean well. Above the cage may be a connecting rod that may couple the rod string to the plunger assembly. In some embodiments, the cage may be of the valve cage type having a ball valve that seats and unseats in response to hydrostatic pressure changes. The valve cage, is an additional check valve that works in unison with the traveling valve.
The plunger, barrel, and cage materials are subject to abrasion from the formation fluid, and some fluids contain various hydrocarbons and gases that may corrode the surfaces of these structures. Additionally, the barrel is subject to loads and stress in two forms radial loads caused by pressure differentials and axial loads acting on the cross-sectional area. Thus, the barrel must withstand burst loading, collapse loading, and axial loading. Materials used in manufacturing have material properties that are resistant to abrasion and corrosion. The SRP assembly may be fabricated from carbon steel, alloy steels, carbon steels with chrome plating, stainless steels, brass, brass alloys, Monel 400®, aluminum, aluminum alloys, induction case hardened steel, or combinations thereof. In some embodiments, the barrel may have a lining or interference material to seal the plunger barrel boundary, such as a high-density polyethylene liner, ceramic coatings, double chrome plating, nickel carbide plating, or combinations thereof. The cage may be fabricated from similar abrasion and corrosion resistance materials, such as alloy steels, brass, Monel, and combinations thereof. However, the cage does not encounter the same abrasive forces as the interference between the plunger and barrel. In some examples, the surface of a metal plunger may be plain steel, chrome or nickel-plated, or sprayed metal. Generally, plunger and the working barrel have a tolerance fit with a tolerance ranging from 0.001 to 0.005 in, measured on the diameter.
The rod string may be operable to linearly translate motion to the plunger and SRP assembly through a pumping cycle. There are two general positions in the pumping cycle, an upstroke and a downstroke. The pumping cycle may be operable to move compressible and/or incompressible fluids from the subterranean well through the pump barrel to the surface. The upstroke of the rod string starts when the plunger has reached the lowermost position, at which point the traveling valve closes due to hydrostatic pressures in the tubing above it. The liquid above the traveling valve (e.g., fluid inside and above the plunger assembly) may be moved toward the surface during the upward movement of the plunger during the upstroke. Simultaneously, the pressure may drop in the space between the standing and traveling valves, causing the standing valve to open. The wellbore pressure drives the liquid from the formation through the standing valve into the section of the barrel below the plunger, increasing the liquid column and filling the barrel with formation liquid for the duration of an upstroke. The total weight of the liquid in the tubing string is carried by the plunger and the rod string connected to it, and due to the high force created by that weight, the rod string may stretch accordingly with the material's elasticity. After the plunger has reached the top of its stroke, the rod string starts to move downwards. As the downstroke begins, the traveling valve immediately opens, and the standing valve closes. This operation of the valves is due to the incompressibility of the liquid contained in the barrel. When the traveling valve opens, liquid weight is transferred from the plunger to the standing valve, causing the tubing string to stretch. During the downstroke, the plunger makes its descent with the traveling valve in an opened configuration, and the barrel fills with formation liquid.
At the end of the downstroke, the direction of the rod string's movement reverses, and another pumping cycle begins. Liquid weight is again transferred to the plunger causing the rods to stretch and the tubing to return to its unstretched state. Because the pumping depth of a well may vary, a typical suction rod section may have a length of 25-30 ft and coupled with rod coupling to provide a rod string length sufficient for the pumping depth. Because a rod string is subjected to constant uniaxial loading and unloading, the rod string is typically constructed of a material with properties that have a high modulus of elasticity and typically have a tensile strength ranging from 90,000-140,000 pounds per square inch (PSI), and yield stress 60,000 PSI-100,000 PSI, and thereby meet the standards set by the API. Materials considered for rod string manufacturing may include steel, polished steel, alloy steel, fiber-reinforced plastic, and composites and combinations thereof.
Both the traveling and standing valves in the system may be API check valve assemblies and operate on a ball-and-seat principle. Seats may be machined, precision ground, and finished from corrosion and erosion-resistant metals. The balls are precision finished, and each ball-and-seat combination may be lapped together to provide a perfect seal. The tolerance of the ball-and-seat is critical to efficient pumping because of the very high differential pressures across the valves during operation. Construction of the ball and seat may be from stainless steel, tungsten carbide, zirconia ceramics, nickel carbides, silicon nitride, titanium carbide, or other alloy materials that are abrasion and corrosion resistant. The materials may be particularly selected for the specific composition of the formation fluid.
The present invention provides a rotor rotatably coupled to the rod string that imparts little to no torque on the rod string and having a fluted surface for allowing flow of the formation fluid to driving rotation of the rotor. The rotor flutes may be operable to on a downstroke drive rotation of the rotor to generate a vortex of well fluid above the plunger assembly. When the fluid contacts the rotor flutes, the fluid applies a force to the flutes due to their angled path along the surface of the rotor, thereby applying a torque to the rotor and causing it to spin relative to the rod string. The rotation of the rotor and the angled flow of the fluid through the flutes may result in a fluid vortex above the rotor, which may turbulently displace particulate and debris, preventing particulates from settling between the barrel and plunger mating surface. The rotor may rotatably couple to the rod string with at least one collar sized to fit around the rod string, while still allowing the rotor to freely spin around the rod string. In some embodiments, there may be two collars operable to secure the rotor at or near distal and proximal points on the rotor operable to enable the rotor to travel in unison with the plunger assembly and still freely rotate around the rod string without obstruction and without applying a torque to the rod string. The rotor may be manufactured through casting, machining, or other appropriate method and constructed from materials such as carbon steels, alloy steels, stainless steels, brass, Monel and combinations thereof.
The present invention provides an improved rotor that may have a generally cylindrical exterior surface having a plurality of flutes formed therein. The rotor may have an internal cylindrical conduit operable to couple around a cylindrical component above the plunger's cage and may be positioned on or around a bearing or the rod string. The flutes cross-sectional geometry may have a curved interior surface that is concentric to the central axis of the rotor. The flutes may have a wall angle having an acute angle to forming a substantially trapezoidal cross-section. In other embodiments, the cross-section geometry of the flutes may be semicircular, semi-ovoid, a composite shape having a rectangular outer portion and a semicircular or semi-ovoid inner portion, and other appropriate shapes. The plurality of flutes may be evenly distributed around the rotor and may have a cumulative cross-sectional area that is substantially equal to the cross-sectional area of the standing valve conduit at the pump intake. The rotor may have an outer diameter that fits in the pump barrel, where the outer diameter is about equal to or less than the diameter of the plunger. The proximal and distal ends of the rotor may have chamfered ends that are operable to direct the fluid into the fluted sections of the rotor. The coupling of the rotor and collars to the rod string may be free-spinning, allowing the rotor to spin freely and thus imparts no torque on the plunger or rod strings. The helical path of the flute may have a rotational path starting from the distal end and ending at a proximal end of the rotor. The rotational path may have a vertical length components substantially equal to the length of the rotor and may have a starting angle of 0 degrees and have a final angle ranging from about 60 degrees to about 210 degrees, the pitch of the helix may be constant.
The cross-sectional area of the flutes at any point along the path may be equal to the cross-sectional area of the intake port of the plunger. The helical path of the flute may be counter-clockwise or clockwise. The helical flutes impart a horizontal force on the rotor, and the rotor of the present invention freely rotates about the neutral axis of the rod string, and the fluted portions of the rotor may distribute the flow of the fluid and cause the fluid to transition from a laminar flow to a turbulent flow. The turbulent flow may prevent the heavier debris in the fluid from settling in the plunger barrel boundary. The present invention is not a rod guide or scraper. Because the rotor may rotate freely around the connecting rod and is not fixedly joined to the plunger, the rotor does not distribute the rotational force imparted from the helical flutes to the plunger assembly, and the generated vortex may have a higher velocity than in a conventional plunger system.
In some embodiments, the rotor may be a swivel rotor that may have a plurality of flutes with a helical geometry and through passages operable to discharge fluid and intake fluid into an upper fluid column. The swivel rotor may have a cylindrical geometry with an internal conduit. The swivel rotor may join the cage to a rod lock, with two collars, the first on an upper surface and the other on a lower surface. The rod lock may extend through the swivel rotor's internal conduit and fasten into cage threading and secure the collars around the swivel rotor, thereby preventing linear translation, but does not compress the swivel rotor. The swivel may be rotatably coupled to the plunger on the swivel's bottom surface and may be rotatably coupled to the rod lock allowing the swivel rotor to freely rotate. The swivel rotor may have a plurality of flutes having a rotational path around the exterior surface and a flute depth that does not penetrate the internal conduit. The swivel may also have one or more through passages that are operable to allow fluid to pass through and enter the internal conduit. The helical flutes may start between the bottom surface and midline of the flute and end between the top surface and the midline having a constant pitch and may have a helical path with a starting angle of 0 degrees and an ending angle of about 360 degrees relative to the central axis of the swivel rotor. The one or more through passages may include a plurality of through passages that are symmetrically distributed between the flutes and may have an equidistant arrangement between the top and bottom surfaces. The through passages may have a substantially circular geometry. The total cross-sectional area at the centroid of a through passage may provide a fluid area substantially equal to the inlet of the traveling valve. The fluid may discharge out of the through-holes and into the helical flutes, allowing the swivel rotor to rotate about the neutral axis, and the fluid may leave the swivel rotor in a substantially turbulent state. The helical structure of the flutes may be machined from the exterior surface or may be otherwise formed (e.g., by casting, etc.) between a top surface and bottom surface but the flutes are not formed through the top surface or the bottom surface. In other embodiments, the flutes may be formed to pass through to the top and bottom surfaces. The one or more through-holes may be positioned on the flute path to provide fluid directly to the rotor and provide a more substantial rotational force to the swivel. In such embodiments, the swivel may prevent heavy debris from entering the plunger barrel boundary because the swivel may have a diameter equal or about equal to the plunger barrel boundary.
In some embodiments, the flutes for the rotor and the swivel rotor may have a circular cross-section, a substantially square cross-section, and a combination thereof but maintain a cross-sectional area substantially equal to the cross-sectional area of the intake valve. The one or more through-holes may have varying geometries as well, including square, diamond, circular, but maintains symmetry about a centerline and has a total flute and through-hole cross-sectional area equal to the intake valve cross-section.
Selected exemplary embodiments of the suction rod pump assembly of the present invention are provided below. It is to be understood that the embodiments are exemplary only, and do not limit the scope of the invention.
In one aspect, the present invention relates to a downhole suction rod pump assembly, comprising a plunger having an internal conduit operable to allow for the passage of formation fluid to a cage for distribution through at least one port, a freely rotatable rotor having flutes, and a rotor concentrically coupled to a connecting rod, and operable to generate a vortex within a barrel, a reciprocating rod string operable to linearly translate the suction rod vertically in the barrel, and during which the rotor flutes are operable to intermittently produce a rotation of the rotor in a direction opposite to the vortex during a suction rods downstroke, and may intermittently stop rotating during a suction rod upstroke. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent formation fluid from penetrating the boundary.
The downhole suction rod assembly may further include a plunger inlet operable to receive the formation fluid and a traveling ball valve therein the plunger inlet being operable to linearly translate to an open and closed position in response to reciprocation of the rod string. The cage may have an open-type cage having a plurality of ports, with a total combined cross-sectional area equal to the inlet of the plunger. The downhole suction rod assembly may further include a standing valve and seating assembly fixed to an inlet of the barrel below the traveling valve. The flutes may have a cross-sectional area equal to the cross-sectional area of the plunger inlet cross-sectional area. The rotor may be operable to prevent debris and particulates from settling between the plunger and barrel boundary, thereby preventing fouling of the barrel and main plunger. The downhole suction rod assembly may further include a collar operable to rotatably couple the rotor to the connecting rod. The rotor flute may have a constant pitch and a helical path around the exterior surface of the rotor with a starting angle of 0 degrees from a rotor's bottom surface and has an ending angle ranging from 60 to 210 degrees at a rotors top surface.
In another aspect, the present invention relates to a downhole suction rod pump assembly, comprising a plunger having at least one internal conduit operable to receive formation fluid from at least one traveling valve intake port and directing formation fluid to a cage for distribution through at least one cage port, a reciprocating rod string operable to linearly translate a suction rod vertically in a barrel, and a rotor concentrically coupled to a connecting rod, where the rotor may have at least one flute with a cross-sectional area equal to the at least one traveling valve intake port and may be operable to generate a vortex of formation fluid in the barrel above the rotor during a down-stroke of the reciprocating rod string, and does not impart a torque on the connecting rod. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent formation fluid from penetrating the boundary. The connecting rod may have a distal and proximal end wherein the distal end may be fastened to the cage and the proximal end may be rotatably secured to the rod string.
The downhole suction rod assembly may further include a pair of collars secured between the connecting rod and the rotor. The rotor intermittently rotates during a downstroke of the rod string in a direction opposite to the vortex rotation and rotation of the rotor seizes during an upstroke of the rod string. The at least one cage port may be a plurality of ports each having a port sized to be substantially equal to the plunger intake. The rotor flute may have a helical path with a substantially constant pitch wrapping around an exterior surface of the rotor starting a bottom surface and ending at a top surface. The rotor flutes may have a total combined cross-sectional area substantially equal to the plunger intake. The rotor helical path may have a starting angle of 0 degrees from the bottom surface and may have an ending angle ranging from 60 to 210 degrees on the top surface of the rotor.
In another aspect, the present invention relates to a downhole suction rod pump assembly, comprising a plunger having at least one internal conduit operable to receive formation fluid from a traveling valves intake port and directs formation fluid to a cage for distribution through a port, a reciprocating rod string operable to linearly translate the suction rod vertically in a barrel, a collar concentrically positioned around a connecting rod and may be operable to rotate freely, a rotor having flutes, where the rotor may be rotatably coupled to the collar, and the flutes may have a combined cross-sectional area substantially equal to the traveling valve intake port, and the rotor further may be further operable to generate a vortex on a down-stroke from the reciprocating rod string. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent formation fluid from penetrating the boundary. The connecting rod may have a distal and proximal end where the distal end may be fastened to the cage, and the proximal end may be fastened to the rod string. The collar may include two collars, one positioned on a rotor's top surface and the other position a rotor's bottom surface. The rotor may intermittently rotate during a downstroke from the rod string in a direction opposite to the vortex rotation and the rotation of the rotor may seize during an upstroke of the rod string. The at least one cage port may have a plurality of ports each having a port sized to be substantially equal to the plunger intake. The rotor flutes may have a constant pitch and a helical path around the exterior surface of the rotor with a starting angle of 0 degrees from a rotors bottom surface and may have an ending angle ranging from 60 to 210 degrees at a rotors top surface.
In another aspect, the present invention relates to a downhole suction rod pump assembly, comprising a plunger having an internal conduit operable to direct a flow of formation fluid from at least one traveling valve intake port, a rotor rotatably coupled between a rod string and the plunger, where the rotor may have an internal conduit, a flute positioned between a top surface and a bottom surface of the rotor, and at least one discharge port for formation fluid to flow into the flute, a reciprocating rod string operable to linearly translate the suction rod vertically in a barrel. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent formation fluid from penetrating the boundary. The flute may be operable to rotate the rotor and generate a vortex of formation fluid above the rotor when the suction rod is in a downstroke. The discharge port and the flute have a combined cross-sectional area that is substantially equal to the traveling valve intake port. The flute may have at least two flutes symmetrically distributed around the circumference of the rotor. The rotor flutes may start between the bottom surface and midline of the flute and ends between the tops surface and the midline having a constant pitch and may have a helical path with a starting angle of 0 degrees and an ending angle of 360 degrees. The at least one discharge port may be a plurality of ports equidistantly arranged along a helical path symmetrical to the at least two flute paths. The at least one discharge port may be a plurality of ports arranged along the rotor flutes. The flutes may be further operable to intermittently produce a rotation of the rotor in a direction opposite to the vortex during a suction rod downstroke, and may intermittently stop rotating during a suction rod upstroke.
In a further aspect, the present invention relates to a downhole suction rod pump assembly, comprising a plunger having at least one internal conduit operable to receive formation fluid from at least one traveling valve intake port and directing formation fluid to a rotor for discharge of formation fluid through at least discharge port, where the rotor has a flute with a cross-sectional area equal to the at least one traveling valve intake port, a reciprocating rod string operable to linearly translate a suction rod vertically in a barrel, and a rotor concentrically coupled to a connecting rod, where the rotor has at least one flute with a cross-sectional area equal to the at least one traveling valve intake port and may be operable to generate a vortex of formation fluid in the barrel above the rotor during a down-stroke of the reciprocating rod string, and does not impart a torque on the connecting rod. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent the formation fluid from penetrating the boundary. The connecting rod may have a bottom surface that is rotatably coupled to a rotors top surface and the connecting rods top surface may be fixedly fastened to the rod string. The suction rod pump assembly may further include a pair of collars securing the rotor from translating in the vertical direction, but allowing for rotation of the rotor. The rotor may intermittently rotate on a downstroke of the rod string in a direction opposite to the vortex rotation and rotation of the rotor may seize during an upstroke of the rod string. The rotor may be fixedly secured to the plunger and the rotor flutes are operable to impart a rotation to the plunger during the downstroke of the rod string. The rotor flute may have a helical path with a substantially constant pitch wrapping around an exterior surface of the rotor starting a bottom surface and ending at a top surface, and may have a combined cross-sectional area equal to the plunger inlet. The helical path of the rotor may have a starting angle of 0 degrees from the bottom surface and may have an ending angle ranging from 60 to 210 degrees on the top surface of the rotor. The rotor flutes may start between the bottom surface and midline of the flute and ends between the tops surface and the midline having a constant pitch and a helical path with a starting angle of 0 degrees and an ending angle of 360 degrees. The rotor flutes are further operable to produce a vortex of formation fluid having a spin equal to the rotor flutes, and may be operable to rotate the plunger in the barrel in a direction opposite to the vortex.
In a further aspect, the present invention relates to a method of extracting a formation fluid from a well using a downhole suction rod pump assembly, comprising moving a reciprocating rod string in a vertically oscillating pattern to linearly translate a suction rod vertically in a barrel, wherein a plunger having at least one internal conduit receives the formation fluid from a traveling valve intake port and directing formation fluid to a rotor for discharge of the formation fluid through at least discharge port, wherein the rotor has a flute with a cross-sectional area equal to the at least one traveling valve intake port; and creating a vortex in the formation fluid during a down-stroke of the reciprocating rod string by rotation of a rotor concentrically coupled to the suction rod pump assembly, wherein the rotor has at least one flute with a cross-sectional area equal to the at least one traveling valve intake port and does not impart a torque to any component of the suction rod pump assembly. The plunger may be sized to fit in a pump barrel such that a boundary between the two has a tolerance operable to prevent the formation fluid from penetrating the boundary. The connecting rod's bottom surface may be rotatably coupled to the rotor's top surface and the connecting rod's top surface is fixedly fastened to the rod string. A pair of collars may secure the rotor from translating in the vertical direction, while allowing for rotation of the rotor. The rotor intermittently may rotate on a downstroke of the rod string in a direction opposite to the vortex rotation and rotation of the rotor seizes during an upstroke of the rod string. The rotor may be fixedly secured to the plunger and the rotor flutes are operable to impart a rotation to the plunger during the downstroke of the rod string. The rotor flute may have a helical path with a substantially constant pitch wrapping around an exterior surface of the rotor starting a bottom surface and ending at a top surface, and have a combined cross-sectional area equal to the plunger inlet. The helical path of the rotor may have a starting angle of 0 degrees from the bottom surface and has an ending angle ranging from 60 to 210 degrees on the top surface of the rotor. The rotor flutes may start between the bottom surface and midline of the flute and ends between the tops surface and the midline having a constant pitch and a helical path with a starting angle of 0 degrees and an ending angle of 360 degrees. The rotor flutes may be further operable to produce a vortex of formation fluid having a spin equal to the rotor flutes, and is operable to rotate the plunger in the barrel in a direction opposite to the vortex.
Further aspects and embodiments will be apparent to those having skill in the art from the description and disclosure provided herein.
It is an object of the present invention to provide an improved rotor operable to generate a vortex above a plunger system without imparting torque to the plunger assembly.
It is a further object of the present invention to provide an improved suction rod pump assembly with an improved cyclic life.
The above-described objects, advantages, and features of the invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the several drawings described herein. Further benefits and other advantages of the present invention will become readily apparent from the detailed description of the preferred embodiments.
Reference will now be made in detail to certain embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in reference to these embodiments, it will be understood that they are not intended to limit the invention. To the contrary, the invention is intended to cover alternatives, modifications, and equivalents that are included within the spirit and scope of the invention. In the following disclosure, specific details are given to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without all of the specific details provided.
The present invention concerns a Suction Pump Rod (SPR) system that may be incorporated into a downhole pumping system or other pumping equipment.
In the embodiment of
The fluid in the system may transition through a variety of different fluid flow states. For example, during the upstroke, as described in
During the downstroke of the rod string 107, the traveling valve immediately opens, and the standing valve 102 closes due to the pressure differential in the plunger's interior cavity 123 and the control volume 130. During the plungers 123 decent fluid may be transferred through the plunger's interior conduit 127, into the plunger's interior cavity 123, and out of the cage 125. When the fluid encounters the plunger's interior cavity 123, the fluid may be in a transient state and return to a substantially laminar flow and may exit cage 125 through cage ports 113 in a transient state. The formation fluid may include a substantial amount of particulates and sediment therein. The sediment and particulates cause damage to conventional drill string components as they flow through the system. Because of the tight tolerances in the suction rod assemblies, granular material (e.g., sand) causes scoring and other damage to components in the suction rod assembly. In embodiments of the present invention, the cage neck 125B may provide a fluid region (area available for fluid to flow) with a greater cross-sectional area than at any other location in the plunger assembly 120, because the fluid region is greater (fluid fills the region around the cage neck 125B and the barrel 101), the fluid has a negative pressure differential after the ports 113. However, when the fluid encounters the rotor 121 the negative pressure differential of the fluid may return to the initial pressure of the fluid when in the plunger's interior conduit 127. The rotor's plurality of flutes 121A when combined have a cross-sectional fluid area equal to the plunger inlet 122, but when the flutes are analyzed independently an individual flute 121A may provide a fluid area as a ratio of one to a plurality of flutes. Individually a rotor flute 121A provides a reduced cross-sectional area for example, if a plurality of provided flutes is six then the rotor flute 121A may provide a one to six cross-sectional fluid region, and if a plurality of provided flutes is four then the rotor flute 121A may provide a one to four cross-sectional fluid region. The individual cross-section of a rotor flute 121A provides a substantially smaller region for fluid to fill and the fluid enters into the flute 121A in a substantially transient state and as the fluid flows through the helical passage of the flute the pressure and velocity increase and the fluid may transition to a turbulent state, at the mid-section of the rotor 121, and may exit the rotor flute 121A in a turbulent state. The rotor flutes 121A may be operable to generate a turbulent region that maintains a substantially helical flow above the rotor 121. During the turbulent state of fluid exiting the rotors flutes 121A, the sediment and debris carried toward the rod string 107 is maintained in the turbulent water column and does not have sufficient time or weight to settle between the plunger 123 and barrel 101 walls. As a result the sediment and debris cannot flow into spaces between the plunger assembly 120 and the barrel 101, or between other structures, thereby preventing the scoring and other damage experienced by conventional SPR systems. The fluid after the turbulent region may transition back to transient state, and ultimately laminar flow as the fluid is lifted to the surface. Thus, the rotor 120 is operable to extend the life of the SPR assembly 100 of the present invention and improves the overall operation of the system.
An exemplary view of the upper portion of a plunger assembly 120 during the downstroke is illustrated in
On the downward stroke, the control volume and formation fluid 130 between the plunger-barrel boundary 101 may enter into the plunger 127 with the traveling valve 128 and standing valve 102 configured as shown in
In some embodiments, the swivel rotor 200 may fixedly attach to the cage 125 on the bottom surface 207 of the swivel rotor 200, and the top surface 206 may be rotatably coupled to the rotor lock 126, allowing for the transfer of torque to the plunger assembly 120 about the rod lock 126. In other embodiments, the swivel rotor 200 may provide the same function as the cage 125 and replace the cage 125. In such embodiments, the fluid may flow upwards through the plunger 127 and out the through-holes 205, and fluid may flow into flutes 210 and producing a rotary torque to the plunger 127. In another embodiment, the swivel's bottom surface 207 may be rotatably coupled to the plunger 123, and the top surface 206 may be rotatably coupled to the rod lock 126 and allowing the swivel rotor 200 to rotate without applying torques to either the rotor lock 126 or the plunger 123.
In another embodiment, it may be advantageous to provide a combination of the rotor 100 and swivel rotor 200 as illustrated in the exemplary view of an upper plunger assembly 120 according to the embodiment shown in
The fluid may flow out the through-holes 205 and enter swivel flutes 210, and travel upwards along the barrel's boundary 101. The fluid may exit out the through-holes 205 in a transient state and may interface with the swivel flutes 210, which may be operable to impart a torque in a clockwise rotation to the plunger 123 without imparting a torque on the rotor swivel junction 150, as shown by the torque line T3. The fluid may then exit the swivel flutes 210 on a rotational path substantially equivalent to the swivel flutes 210, and the fluid may then come into contact with the rotor 121. The fluid may enter into the rotor flutes 121A, displacing debris and particulates in the formation fluid, and may exit the rotor flutes 121A in a substantially turbulent state. The flutes 121A may be operable to impart a rotation to the rotor 121 as shown by the torque line T4 without applying any additional torque to the system, and the fluid may be in a vortex when exiting the flutes 121A. The plunger 123, swivel rotor 200, and rotor may rotate in their respective directions, and the junction 150 rotor lock 126 and rod string 107 may not rotate. The swivel rotor 200 rotation distributes the wear on the plunger 123 to be more uniformly around the circumference of the plunger, and the rotor 121 may rotate in the opposite direction and displace debris in the fluid preventing debris from settling between the boundary of the inner wall of the barrel 101 and the plunger 120.
On the upstroke of the rod string, the traveling valve 128 may be in the closed position as shown in
In other implementations of the present invention, the rotor flutes 121A helical path may have a counter-clockwise path that orients the flutes 121A in the opposite direction as illustrated in
The present invention provides an improved suction rod pump assembly with a rotor operable to displace formation fluid above a plunger assembly, thereby preventing debris in formation fluid from settling between a plunger and barrel boundary. The present invention is operable to generate a vortex of fluid above the plunger assembly without imparting a torque onto the system. It is to be understood that variations, modifications, and permutations of embodiments of the present invention, and uses thereof, may be made without departing from the scope of the invention. It is also to be understood that the present invention is not limited by the specific embodiments, descriptions, or illustrations or combinations of either components or steps disclosed herein. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. Although reference has been made to the accompanying figures, it is to be appreciated that these figures are exemplary and are not meant to limit the scope of the invention. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
