Manufacturing rubber liners for composite PCP stators

Abstract

Techniques for forming a spiral rubber hose are provided. Such techniques include modified crosshead extrusion techniques in which an elastomer is melted, fed into a crosshead assembly, and extruded on a helical mandrel passing through the crosshead assembly to form a hose. In the techniques described herein, the relative axial and rotational movements of the mandrel and a mold plate located at or on the outlet or output of the crosshead assembly are kinematically matched such that the distance of the relative axial movement per revolution of the mandrel equals one pitch of the mandrel.

Description

[0001] Cross-reference paragraphs

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 366,880, filed on June 23, 2022, entitled “COMPOSITIONS AND METHODS FOR WELLCEMENTING,” the disclosure of which is hereby incorporated by reference into this document. Technical Field

[0003] The present disclosure relates generally to stators and methods of making the same, and more particularly, to stators for progressive cavity pumps and methods of making the same. Background Art

[0004] Oil and gas wells utilize a borehole that is drilled into the ground and then completed with equipment in order to produce the desired fluid from the reservoir. Underground fluids (such as oil, gas and water) are typically pumped or "lifted" from the wellbore by the operation of a downhole pump (e.g., a progressive cavity pump (PCP)). The PCP includes a single rotor with a spiral outer surface that rotates within a spiral double-lobed elastomeric liner formed in a coupled stator. In use, as the rotor rotates within the stator, the fluid is transmitted from the inlet at the bottom of the pump to the outlet at the top through a series of cavities formed between the rotor and the stator. The motor drives the rotation of the rotor. The motor can be located at the surface of the wellbore and can be connected to the rotor via one or more sucker rods. Alternatively, the PCP rotor can be driven by a motor submerged in the well. Summary of the invention

[0005] In some configurations, a method of forming a hose includes: melting an elastomer; providing the molten elastomer to a crosshead assembly, wherein a die plate having an outlet port is mounted on the outlet of the crosshead assembly; moving a spiral mandrel through the crosshead assembly and the die plate outlet port while extruding the molten elastomer around the mandrel; and kinematically relating relative axial and rotational movement between the mandrel and the die plate.

[0006] In some configurations, a spiral hose is formed by this method. In some configurations, the spiral hose is incorporated into a stator for a progressive cavity pump or a positive displacement motor.

[0007] In some configurations, the mandrel is anti-rotational and the mold plate is configured to rotate about its longitudinal axis along which the mandrel extends through the mold plate. In some such configurations, kinematically relating relative axial and rotational movement between the mandrel and the mold plate includes axially moving the mandrel a distance equal to one thread pitch of the mandrel when the mold plate rotates one revolution. In some configurations, the mold plate is anti-rotational and the mandrel is configured to rotate about its longitudinal axis. In some such configurations, kinematically relating relative axial and rotational movement between the mandrel and the mold plate includes rotating the mandrel 360° about its longitudinal axis when the mandrel axially travels a distance equal to one thread pitch of the mandrel.

[0008] The elastomer may be rubber. Extruding the molten elastomer around the mandrel may include extruding the molten elastomer through a gap between an outer diameter of the mandrel and an inner diameter of the die plate outlet port.

[0009] In some configurations, a method for manufacturing a stator for a progressive cavity pump includes forming a spiral hose; inserting the spiral hose into a stator tube; and filling a gap between an outer diameter of the spiral hose and an inner diameter of the stator tube with a material.

[0010] The material may be a thermosetting resin. The method may further include curing or vulcanizing the thermosetting resin to solidify and bond the material to the spiral hose. The spiral hose may be made of rubber. The spiral hose may be formed around a mandrel, and the method may further include removing the mandrel from the spiral hose.

[0011] In some configurations, a method of curing a rubberized mandrel includes: applying a protective layer to the rubberized mandrel; surrounding the rubberized mandrel with a slurry or a sand / binder mixture; allowing the slurry to solidify to form a shell around the rubberized mandrel; heating the rubberized mandrel and the shell to cure the rubber; and flushing or crushing the shell formed by the solidified slurry or sand / binder mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Certain embodiments, features, aspects and advantages of the present disclosure will be described below with reference to the accompanying drawings, wherein the same reference numerals represent the same elements. It should be understood that the accompanying drawings illustrate various implementations described herein and are not intended to limit the scope of the various technologies described herein.

[0013] Figure 1 An example PCP system is shown.

[0014] Figure 2 A cross section of a cPCP stator is shown.

[0015] Figure 3 A 3D perspective view of a portion of the friction lining of a cPCP stator is shown.

[0016] Figure 4 Various aspects of crosshead extrusion technology on a mandrel are shown.

[0017] Figure 5A A partial longitudinal cross-section of a spiral rubber hose formed on or around a spiral mandrel is shown.

[0018] Figure 5B Shows Figure 5A A partial 3D perspective view of the rubber hose and mandrel.

[0019] Figure 6 An example technique for forming a spiral rubber hose is shown.

[0020] Figure 7 Another example technique for forming a spiral rubber hose is shown.

[0021] Figure 8 An example ball transmission bearing is shown.

[0022] Fig. 9 Another example technique for forming a spiral rubber hose is shown.

[0023] Figure 10 to Figure 11 Shows possible defects that may occur after improper curing.

[0024] Fig.12 The steps for making a disposable housing for curing a rubberized mandrel are shown.

[0025] Fig.13 An alternative mold is shown. DETAILED DESCRIPTION

[0026] In the following description, many details are set forth to provide an understanding of some embodiments of the present disclosure. It should be understood that the following disclosure provides many different embodiments or examples for realizing the different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. However, it will be understood by those of ordinary skill in the art that systems and / or methods can be practiced without these details, and that various changes or modifications can be made to the described embodiments. This description should not be considered restrictive, but is made only to describe the general principles of implementation. The scope of the described implementation should be determined with reference to the published claims.

[0027] As used herein, the terms "connect", "connection", "connected", "in connection with", and "connecting" are used to mean "directly connected with" or "connected with via one or more elements"; and the term "set" is used to mean "one element" or "more than one element". In addition, the terms "couple", "coupling", "coupled", "coupled together", and "coupled with" are used to mean "directly coupled together" or "coupled together via one or more elements". As used herein, the terms "upper" and "lower", "upper" and "lower", "top" and "bottom", and other similar terms indicating relative positions relative to a given point or element are used to more clearly describe some elements. Generally, these terms involve taking a reference point at the ground from which the drilling operation is to be started as the vertex and the total depth as the lowest point, where the well (e.g., wellbore, borehole) is vertical, horizontal, or inclined relative to the ground.

[0028] Figure 1 An example PCP system 100 is shown. As shown, the PCP system 100 includes a pump (i.e., PCP) 110, one or more sucker rods 120, and an electric motor 130. The PCP 110 includes a single helical rotor 112 that, when in use, rotates inside a double helical stator 114. During operation, as the rotor 112 rotates within the stator 114, fluid 106 is passed from an inlet at the bottom of the pump 110 to a discharge or outlet at the top of the pump 110 through a series of cavities 116 formed between the rotor 112 and the stator 114.

[0029] In use, the PCP 110 is disposed in a borehole lined with a well casing 102 downhole. An electric motor 130 is disposed at the surface of the well. Sucker rods 120 extend between and connect (e.g., physically and / or operatively connect) surface components of the system 100 (such as the electric motor 130) and downhole components of the system 100 (such as the PCP 110). Each sucker rod 120 may be threaded at one or both ends to enable threaded connection with other components (such as the PCP 110 (i.e., the rotor 112), surface components, and / or other sucker rods 120). In use, the motor 130 rotates or causes the sucker rods 120 to rotate, which in turn rotates or causes the rotor 112 to rotate. A production tubing 104 may be disposed in the borehole to deliver a pumped fluid 106 discharged from an outlet of the PCP 110 to the surface. In the illustrated configuration, the tubing 104 is disposed about or surrounds the sucker rod 120 .

[0030] The present disclosure relates to a manufacturing method for producing a composite PCP stator or cPCP stator. Figure 2 A cross section of an example cPCP stator is shown. As shown, the cPCP stator has an inner rubber liner or layer, an outer metal tube, and a thermosetting resin between (eg, radially between) the rubber liner and the metal tube.

[0031] A method or process for making a cPCP stator may include: making a rubber hose that will become the rubber lining of the stator; placing the rubber hose over, around, or around a mandrel (e.g., a metal mandrel) (or inserting the mandrel into a hollow rubber hose); inserting the mandrel with the rubber hose into a metal stator tube; filling the gap between the rubber hose OD (outer diameter) and the stator tube ID (inner diameter), for example, with a thermosetting resin; and curing (e.g., vulcanizing) the thermosetting resin (or other material used to fill the gap) to solidify the material and bond it to the rubber hose; and removing the mandrel from the cPCP stator. The rubberized mandrel may be manufactured so that the rubber thickness is precisely controlled and there is no adhesive or sticky element between the mandrel and the rubber hose formed thereon.

[0032] The present disclosure provides a method for manufacturing a spiral-shaped rubber hose in an accurate and controllable manner. In some configurations, a crosshead extrusion technique allows rubber to be formed into a desired spiral shape. During this process, the rubber can remain on the mandrel. The technology utilizes an axially movable mandrel, and relates to a kinematic matching rotation between the mandrel OD (outer diameter) that forms the rubber hose ID (inner diameter) and the die plate that forms the rubber hose OD. The mandrel performs an axial movement of a pitch that matches a rotation relative to a die position, and the die position can be a rotatable or non-rotatable feature.

[0033] The method according to the present disclosure can be based on conventional cross-head extrusion technology on a mandrel (e.g. Figure 4 The crosshead extrusion technology of the present invention is generally used for the production of cylindrical rubber rollers. ...

[0034] According to the present disclosure, the crosshead extrusion technique on a mandrel is modified to form a spiral rubber hose, e.g. Figure 3 In the technology according to the present disclosure, the mandrel is spiral-shaped, such as FIG. 5A to FIG. 7 As shown. The mandrel can be considered or similar to a double-thread or double-start screw, in other words, having two heads. One mandrel pitch (or lead) corresponds to, is equal to, or is approximately or substantially equal to one pitch of a spiral rubber hose formed by the technology according to the present disclosure, such as Figure 5A and Figure 5B In other words, if the spindle is threaded with an imaginary nut, the thread pitch can be defined as the axial distance the nut travels along the spindle with or during one rotation of the nut.

[0035] The technology according to the present disclosure introduces a rotational degree of freedom to the mandrel and / or the die plate during the extrusion process. The technology according to the present disclosure also includes a kinematic relationship between the axial movement of the mandrel and (1) the rotation of the mandrel relative to the non-rotatable die plate or (2) the rotation of the die plate relative to the non-rotatable mandrel. In (1) (rotation of the mandrel relative to the non-rotatable die plate, for example, Figure 6 In the case of (2) (rotation of the mold plate relative to the non-rotatable mandrel, e.g., Figure 7 In the case of an extruder (shown in FIG. 1 ), the die plate rotates 360° about its longitudinal axis (the axis that extends through the die exit and extends and travels with the mandrel as the mandrel moves through the crosshead assembly and the die plate during extrusion) when the mandrel travels an axial distance equal to one mandrel pitch.

[0036] In the technique where the mandrel rotates relative to a fixed die plate, e.g. Figure 6As shown, guide pins may be included and used to provide or ensure proper kinematic matching or interaction between the mandrel and the die plate. The guide pins are anchored to a fixed unit or piece of equipment, for example, to the extruder or to a separate component mounted to the floor. In the configuration shown, two guide pins are included. During extrusion, the tips of the pins are in constant contact with the sides of the mandrel, thereby generating friction on the mandrel and causing movement of the mandrel. If the pitch of the mandrel is relatively shallow, the primary load applied to the mandrel during extrusion should cause the mandrel to move axially through the crosshead assembly. In such cases, the pins would cause rotational movement of the mandrel. If the pitch of the mandrel is relatively steep, the primary load applied to the mandrel during extrusion should cause the mandrel to rotate. In such cases, the pins would cause the mandrel to travel axially. In some configurations, the tips of the pins may be designed as ball drive bearings, for example, as in Figure 8 In some configurations, the pins may be replaced with custom rollers that align with the helix of the mandrel.

[0037] In the technique where the die plate is rotated relative to a non-rotatable mandrel, e.g. Figure 7 As shown, the mandrel is non-rotatable and is pushed or pulled axially through the crosshead assembly. The die plate is mounted on a rotatable die located at the outlet or output end of the crosshead assembly. The RPM of the die is related to the axial speed of the mandrel so that one rotation of the die corresponds to an axial movement of the mandrel equal to one pitch.

[0038] Other variations of the technology (e.g., other motion schemes) are possible in accordance with the present disclosure. For example, the mandrel may be axially fixed and non-rotatable, while the mold plate may be axially movable and rotatable, such that the mold plate rotates and moves axially relative to the fixed mandrel. As another example, the mandrel may be rotatable but axially fixed, while the mold plate may be axially movable but non-rotatable, such that when the mold plate moves axially along or relative to the axially fixed mandrel, the mandrel rotates within the mold plate. As another example, both the mandrel and the mold plate may be rotatable and axially movable.

[0039] Fig. 9 Alternative methods for rubberizing the mandrel are shown. Fig. 9 As shown, the mandrel can be wrapped with a relatively thin tape made of green (uncured) elastomer. The desired thickness of the rubber lining can be achieved by covering the mandrel with one or more layers of thin rubber strips.

[0040] In extrusion (e.g. Figure 6 to Figure 7 as shown and described with respect thereto) or a package (e.g. Fig. 9After the rubberized mandrel is cured, the rubberized mandrel is cured. Temperature, time, pressure and "boundary" constraints are critical parameters of the curing process. Pressure is required to consolidate the rubber lining and achieve the overall material structure. Without sufficient pressure, various types of voids and delamination defects may occur. For example, Fig.10 Shows voids that appear in a rubber hose due to insufficient applied pressure to solidify the rubber. Boundary constraints prevent the rubber from deforming as it cures and ensure that the rubber lining achieves and maintains the desired shape. Fig.11 The rubber extruded on a cylindrical mandrel is shown to deform due to the lack of boundary constraints. Although a cylindrical rubberized mandrel can be wrapped with a special elastic tape to ensure that the rubber lining is stressed and does not deform excessively during curing, such wrapping is insufficient for the spiral geometry of the present disclosure because wrapping the spiral mandrel does not form a uniformly tensioned tape layer.

[0041] In the system and method according to the present disclosure, a profiled rubberized mandrel is cured using a disposable shell or mold that mimics the outer shape of an uncured elastomer layer placed on a rigid mandrel. The shell is made of a special slurry or sand / binder mixture. This free-flowing medium is able to encapsulate complex parts and allow the medium to solidify.

[0042] Fig.12 The steps for making such a shell are shown. First, the rubberized mandrel is covered with a protective layer that can withstand the curing temperature (typically 150°C or 300°F), for example, by wrapping the mandrel with PTFE tape. The tape tension does not need to be too high and should not deform the raw rubber. The mandrel with the protective layer is then placed in a bath or tray. The bath is filled with a special slurry, which can be Aquapour material or similar material. Aquapour is supplied in powder form and can be mixed with water to obtain a pourable slurry. Depending on the water content, a setting time of approximately 30 to 60 minutes is required for the slurry to solidify. The slurry eventually encapsulates the mandrel. After solidification, the slurry forms a shell that follows or mimics the shape of the outer rubber surface.

[0043] The tub or tray is then placed in an oven for the curing process. The slurry shrinks during curing, thereby generating pressure, which consolidates the elastic layer. After curing, the tub or tray is removed from the oven and cooled. The solidified slurry is washed away, for example with standard tap water. Finally, the protective layer is removed from the fully cured rubber layer.

[0044] Fig.13 An alternative mold is shown. Instead of an open tub or tray, a rubberized mandrel can be placed in a tubular housing. Although not shown, a protective layer is still used. The space between the rubber layer and the housing ID is filled with slurry or sand mixed with a binder. Fig.13The mold and associated process can advantageously allow very high pressures to be generated when required and / or can make the sand / binder mixture recyclable. After curing, the shell can be broken up and a binder can be added to restore the setting properties.

[0045] exist Figure 12 to Figure 13 The systems and methods shown and described herein advantageously allow for substantial pressure to be applied to the green (uncured) rubber to ensure good quality elastomeric structure and to prevent deformation of the rubber shape upon curing.

[0046] Extrusion or manufacturing techniques according to the present disclosure may also be used or alternatively used to manufacture articles other than PCP stators. For example, technology according to the present disclosure may be used to manufacture a stator for a positive displacement motor (PDM), such as that to be used in drilling operations. As another example, technology according to the present disclosure may be used or adapted to manufacture rotors (e.g., PCP and / or PDM rotors). Extrusion techniques according to the present disclosure may be used to cover such rotors with a layer of rubber or plastic. In general, technology according to the present disclosure may be used to manufacture helical tubes that may be disposed within or around other components of an article.

[0047] The degree language used herein (such as the terms "approximately", "about", "substantially", and "substantially") as used herein refers to a value, amount, or characteristic that is close to the value, amount, or characteristic that still performs the desired function or achieves the desired result. For example, the terms "approximately", "about", "substantially", and "substantially" can refer to an amount that differs from the amount by less than 10%, less than 5%, less than 1%, less than 0.1%, and / or less than 0.01%. As another example, in certain embodiments, the terms "substantially parallel" and "substantially parallel" or "substantially perpendicular" and "substantially perpendicular" refer to a value, amount, or characteristic that differs from completely parallel or perpendicular by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degrees, respectively.

[0048] Although several embodiments of the present disclosure have been described in detail above, it will be readily appreciated by those skilled in the art that many modifications may be made without departing substantially from the teachings of the present disclosure. Therefore, such modifications are intended to be included within the scope of the present disclosure as defined in the claims. It is also contemplated that various combinations or sub-combinations may be made to the specific features and aspects of the described embodiments and still fall within the scope of the present disclosure. It should be understood that the various features and aspects of the disclosed embodiments may be combined with or substituted for each other to form different modes of the embodiments of the present disclosure. Therefore, it is desired that the scope of the present disclosure should not be limited to the specific embodiments described above herein.

Claims

1. A method of forming a hose, the method comprising: Melting the elastomer; providing the molten elastomer to a crosshead assembly, wherein a die plate having an outlet port is mounted on an outlet of the crosshead assembly; moving a spiral mandrel through the crosshead assembly and the die plate exit port while extruding the molten elastomer around the mandrel; as well as The relative axial and rotational movements between the mandrel and the die plate are kinematically related.

2. The method of claim 1, wherein the mandrel is rotation-resistant and the mold plate is configured to rotate about a longitudinal axis along which the mandrel extends through the mold plate.

3. The method of claim 2, wherein kinematically relating the relative axial and rotational movement between the mandrel and the die plate comprises axially moving the mandrel a distance equal to one thread pitch of the mandrel when the die plate rotates one revolution.

4. The method of claim 1, wherein the mold plate is rotation-resistant and the mandrel is configured to rotate about its longitudinal axis.

5. The method of claim 4 wherein kinematically relating the relative axial and rotational movement between the mandrel and the mold plate comprises rotating the mandrel 360° about its longitudinal axis as the mandrel travels axially a distance equal to one thread pitch of the mandrel.

6. The method of claim 1, wherein the elastomer is rubber.

7. The method of claim 1, wherein extruding the molten elastomer around the mandrel comprises extruding the molten elastomer through a gap between an outer diameter of the mandrel and an inner diameter of the die plate exit port.

8. A spiral hose formed by the method of claim 1.

9. A stator for a progressive cavity pump, the stator comprising the spiral hose according to claim 8.

10. A method for manufacturing a stator for a progressive cavity pump, the method comprising: forming a spiral hose; inserting the spiral hose into the stator tube; as well as The gap between the outer diameter of the spiral hose and the inner diameter of the stator tube is filled with material.

11. The method of claim 10, wherein the material is a thermosetting resin.

12. The method of claim 11, further comprising curing or vulcanizing the thermosetting resin to solidify and bond the material to the spiral hose.

13. The method of claim 10, wherein the spiral hose is rubber.

14. The method of claim 10, wherein forming the spiral hose comprises the method of claim 1.

15. The method of claim 10, wherein forming the spiral hose comprises forming the spiral hose about a mandrel, and further comprising removing the mandrel from the spiral hose.

16. A method of curing a rubberized mandrel, the method comprising: applying a protective layer to the rubberized mandrel; surrounding the rubberized mandrel with slurry or a sand / binder mixture; allowing the slurry to set to form a shell around the rubberized mandrel; heating the rubberized mandrel and the housing to cure the rubber; as well as The shell formed by the set slurry or sand / binder mixture is washed away or crushed.

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