Pressure-balanced low-polymer-degradation GEL injection control valves and related methods of use

Abstract

A flow control valve for viscous fluids has a housing with an inlet, an outlet, and an internal bore; a moving part and a seating part that have intermeshing ribs and collectively define a primary radial flowpath from the inlet to the outlet, the moving part being mounted to axially translate, relative to the seating part, within the internal bore of the housing, to adjust a resistance to flow within the primary flowpath, with the flow control valve structured to balance pressure across the moving part; and a valve positioner connected to adjust an axial position of the moving part.

Description

PRESSURE-BALANCED LOW-POLYMER-DEGRADATION GEL INJECTION CONTROL VALVES AND RELATED METHODS OF USE TECHNICAL FIELD

[0001] This document relates to pressure-balanced low-polymer-degradation gel injection control valves and related methods of use.

[0002] BACKGROUND

[0003] The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.

[0004] The present disclosure relates to the injection of water and other fluids containing viscosityenhancing polymers or gels into reservoirs for enhanced oil recovery or other forms of well stimulation.

[0005] During oil recovery operations, several wells are drilled in a reservoir. These wells may be divided into injection wells and production wells. In most cases, water is forced into the reservoir through the injection wells to maintain the pressure difference with the surface and ensure the flow of oil through the formation; oil is pushed and replaced by the injected water. Often however, water mobility is higher than oil mobility leading to unstable fronts and viscous fingering. As a consequence, the macroscopic sweep efficiency is poor, large areas of the oil-bearing formation are not swept, and oil is left in place. Increasing viscosity of the injected water decreases the mobility ratio between water and oil, improving the macroscopic sweep efficiency. Very high molecular weight polymers may be used in order to maximize viscosifying power, however such polymers may be susceptible to breakage under shear or extension conditions.

[0006] A water injection system comprises a primary water injection pump with injection lines that inject water into wells of different hydraulic resistance. To avoid excessive flow into the wells with the lowest hydraulic resistance, a choking valve may be installed at each wellhead to control the flow rate injected into each well. A choke coil, a globe valve or other throttling valve device is used for the purpose. Types of polymers used, such as acrylamide based polymers, feasible concentrations and technical solutions for mixing with injection water, for specific reservoir conditions, are in this context assumed to be known in general for the skilled person.

[0007] Description of relevant technology regarding various primary flowpaths can be found in patents / patent publications US6701957 (US 2005 / 252559 Al), US10053956 (WO 2014 / 178723 Al), US6782920 (US2003 / 0188787), US10989234 (WO 2015 / 092334 A2), U.S. Pat. No. 3,514,074 A, U.S. Pat. No. 4,276,904, U.S. Pat. No 4,782,847, WO 2015 / 112908A2 (CA2936929), US9260937 (WO 2012 / 001671 A2), U.S. Pat. No. 4,510, 993 A, U.S. Pat. No. 3,477,467A, U.S. Pat. No. 4,617,991A, US10378323 (WO 2017 / 105250 Al), and U.S. Pat. No. 4,279,274A. Description of relevant technology regarding various pilot-controlled valves, and pressure regulators can be found in patents / patent publications US4844112A, US4987920A, US5641271A, EP0862101A1, EP3396218A1, US10753504B2 (US11441694B2, WO2018208851A1), AU642438B2, US5732929A, US4725038A, US6758238B2, US4541454A, US6244563B1, US5215286A, US5234026A, US5072749A, US4336918A, US4473210A, US4274433A, US2891569A, US5890508A, US8640732B1, and US2721570A.

[0008] A demand exists for improved technology for distributing the injection of water or other fluid containing viscosity-enhancing polymers into reservoirs using a network of wells with varying injectivity and reservoir pressures.

[0009] SUMMARY

[0010] Flow control valves are disclosed.

[0011] A flow control valve for viscous fluids is disclosed comprising: a housing with an inlet, an outlet, and an internal bore; a moving part and a seating part that have intermeshing ribs and collectively define a primary radial flowpath from the inlet to the outlet, the moving part being mounted to axially translate, relative to the seating part, within the internal bore of the housing, to adjust a resistance to flow within the primary flowpath, with the flow control valve structured to balance pressure across the moving part; and a valve positioner connected to adjust an axial position of the moving part.

[0012] A method is disclosed comprising using a flow control valve to limit a maximum injection pressure of a viscous injection fluid supplied to the flow control valve via an injection control valve, in which a hydraulic control system supplies the viscous injection fluid to the flow control valve.

[0013] In some embodiments, a flow control valve is disclosed with a relatively long flow pathway formed by intermeshing ribs of two discs. The flow pathway cross-sectional area may be changed by axial movement of one or both of the discs, with a pressure-balancing flowpath to a back side of the moving disc. One use for such a valve may be for regulating the pressure or flow rate of polymer- viscosified water injection distribution between a network of wells or even into a single well in some cases. The ribs may form a labyrinthine or spiral shaped flowpath or a tortuous radial flowpath. The ribs or disc structure may comprise an undulating surface creating a repetitive gradual expansion and contraction of the cross-sectional flow area along the flowpath. A moving disc or other structure of the valve may provide an auxiliary flowpath for pressure-balancing. Two or more auxiliary flowpaths may be used to allow fluid to travel around the outer surface within the bore and through a central flowpath. A moving disc may float in the housing, for example may not be rigidly connected to be moved by an actuator, and instead may be moved by forces generated by hydraulic pressure differentials between its flow-side and its backside. A central flowpath may be formed at an interface between the moving disc and a valve positioner. A valve positioner may be controlled by conventional mechanical means or by a pilot hydraulic circuit or a combination of a pilot hydraulic circuit with a mechanical override.

[0014] Some embodiments disclosed here may meet demand by providing a water injection flow control device, distinguished in that it comprises one or more of:• a pair of discs comprising intermeshing ribs;• intermeshing ribs forming a flowpath at the root of the rib pattern of each disc;• one disc being stationary and another being a moving disc;• the moving disc being axially translatable within a bore;• a flowpath that changes in cross-sectional area in response to axial translation of a moving disc;• an inlet operatively coupled to either the radially inner or radially outer ends of the flowpath and an outlet operatively coupled to the other of the radially inner or radially outer ends of the flowpath;• a valve positioner that controls the axial position of the moving disc; and• the moving disc comprises an inner auxiliary flowpath for backside pressure-balancing.

[0015] The water injection flow control device may comprise sections in series with alternating large and small cross-sectional area for flow, similar to the teachings of U.S. Pat. No: 10,378,323. Alternating sections of large and small cross-sectional area for flow may allow minimal polymer degradation with a more compact device. Alternating cross-sectional area for flow may be accomplished by varying the thickness of the ribs, or by varying the profile of the disc at the root of the ribs, or by varying the crest profile of the ribs (the height of the ribs).

[0016] Embodiments of the present disclosure may provide a desired pressure loss at an injection rate combined with minimal polymer degradation, in a more compact, low weight unit, with infinite resolution within the range of choke settings. Water-soluble polymers used for mobility control application are in general high molecular weight polymers that are sensitive to mechanical degradation. When submitted to extensional flows such as those encountered in contractions or turbulent eddies, polymer coils undergo a coil-stretch transition as stretched. As the chain starts to extend, hydrodynamic force exerted through the friction of the water on the stretched chain is increased, and may lead to chain rupture at a critical strain rate. Chain break up may lead to a decrease of the solution viscosity. This degradation is irreversible. In a classical plug and cage choke valve, part of the pressure drop is coming from the passage through small holes and from the collision of the fluid at the interior of the cage. During its passage through the holes, the fluid is subjected to very high strain rate (the extensional component of this type of flow is very high). At the interior of the cage, the fluid is once again submitted to the elongational component of the highly turbulent flow. The embodiments of the present disclosure may use existing structures that use a controlled extensional strain rate to create pressure drop and thus, minimize polymer degradation within an infinitely adjustable and economical valve design. There exists a window of strain rate in which polymer develops elongational viscosity and pressure drop without being degraded. Undulations within the cross-sectional of the channel may use the elongational viscosity but keep the strain rate under its critical value to minimize polymer degradation.

[0017] The number of undulations in cross-sectional area may be viewed as a design parameter for achieving acceptably low degradation within an operating range of pressure drop (dP) across the valve. The present disclosed subject matter may vary the cross-sectional area of the flowpath to control the dP and / or flowrate. When undulations are made by varying the thickness profde of the ribs in a spiral or labyrinthine flowpath, then the ratios between period-throat-belly of the flowpath may remain constant as the valve position changes. When undulations are made by varying the crest or root profile of the ribs in a spiral or labyrinthine flowpath, then the ratios between period-throat-belly of the flowpath may vary as the valve position changes. The period of undulations, and the height of undulations need not be constant along the flowpath; for example radial alignment of rib crests requires that undulations have alarger period at a larger diameter. If similar angles of convergence and divergence are used, then undulations at a larger diameter with a larger period may have a greater larger crest height, or a deeper trough.

[0018] Sections with large cross-sectional area for flow are not necessarily identical, and sections with small cross-sectional area for flow are not necessarily identical.

[0019] Preferably, the period P between the alternating sections with large and small cross- sectional area for flow is in a range 1 to 40 d, where d is a minimum dimension in the flowpath transverse to a central flow line through the sections of small cross-sectional areas for flow. D is a maximum dimension in the flowpath transverse to a central flow line through the sections of largest cross-sectional flow. In an embodiment with spiral or labyrinthine primary flowpaths, the sections with small cross- sectional area for flow have in substance a rectangular cross-sectional shape and the sections with large cross-sectional area for flow also have in substance a rectangular cross-sectional shape. In an alternative embodiment with frustoconical ribs, the sections are annular. The ratio of D:d is in a range 1.01-1000, preferably about 2.

[0020] The alternating sections of large and small cross-sectional area for flow, per se, can be according to the teaching of WO 2015 / 092334 A2, the teaching of which publication is incorporate herein by reference if permitted by law.

[0021] Large disc structures that are axially translatable may have significant challenges in several areas: (1) manufacturing and assembling intermeshing ribs of the required tolerances, (2) debris tolerance in operation, (3) large pressures generated by pressures acting on large surface areas; these forces: deflect the structures and affect tolerances and are impractically high for cost effective actuators to reliably function on.

[0022] The floating disc structure of the present disclosure may reduce and avoid many of the previous issues by reducing the stresses on the disc structures, and in some embodiments, using these hydraulic forces for disc movement.

[0023] The outlet may comprise a central channel, meaning an inner channel or hole, penetrating the stationary disc, preferably but not necessarily coaxial along a centerline of the bore. In one case the inlet or the outlet is defined through a central hole of the seating part. The inlet preferably comprises an outer channel, as an annular channel or a peripheral channel with flow past the outside of the stationary disc. Which channel is part of an inlet and an outlet, respectively, is interchangeable, although the decision may affect which side of the moving disc the interface may be formed at for the inner auxiliary flowpath (described further in Fig. 3A).

[0024] In some preferable embodiments, the flowpath cross-sectional area for flow may be enlarged at an inlet and at an outlet for each spiral shaped flowpath. The enlarged cross-sections, at the inlet especially, may reduce the acceleration of the fluid and thus minimize the elongational component of the flow. In other words, the velocity differential in the direction of the flow called the strain rate, shear rate and turbulence may be minimized and as a consequence, polymer degradation is minimized. The cross-sectional area for flow may be enlarged by up to at least 100%, or more, although for a device witha moving plate which changes the cross-sectional area of flow, this enlargement at the inlet and outlet will vary depending on the position of the valve, and at wide open positions may have a lower enlargement. Preferably, the spiral shaped flowpaths have an in substance even cross-sectional area for flow between the inlet and outlet parts, at the smaller cross-sectional for flow.

[0025] The transitions from flowpath cross-sectional area between sections with small and large cross-sectional area for flow preferably may be gradual, which reduces strain rate, turbulence and shear rate. The gradual transitions may be radiused to avoid sharp comers at the small cross-sectional area, to minimize breaking up of polymers. Quite the opposite of classical venturi design (which minimizes pressure loss in a high Reynolds number flow), a preferable angle of convergence may be lower than the angle of divergence. Angles of convergence and divergence are discussed throughout as an included angle -the angle measured from wall to wall. It may be simpler to measure the included angle, since the flow passageway cross-sectional may be rectangular, with only one of the walls being angled to form a converging or diverging passageway. While lower angles may be preferable to reduce strain rate, higher angles allow for a greater number of sections in series of alternating large and small cross-sectional area for flow. Including many alternating sections of large and small cross-sectional area for flow is also very important as it reduces the pressure drop per alternating section.

[0026] The number of sections in series of alternating large and small cross-sectional area for flow may be at least two, more preferably at least ten, such as 20 or 50 or 100, 500, 1000 or more. Some potential rib configurations including those that create a labyrinthine, or frustoconical structures create a serpentine pathway where there are approximately 180 degree turns in the flow direction, these turns in the flow direction may also be advantageous for creating pressure drop with minimal degradation, similar to the alternating large and small cross-sections for flow.

[0027] Each flowpath may have a suitable length, such as a length in the range 0.2-1000 m, preferably 0.2-200 m, or 0.2-100 m, 1-100 m or 1-25 m, or 0.2-50 m, or 2-50 m. Length of a flowpath is not necessarily the best parameter to compare degradation performance of valves. For example, a frustoconical rib structure creates a substantially shorter flowpath with a flowing cross-sectional of a very thin annular shape, which for the purposes of calculating pressure drop and performance may be approximated as a rectangle with a very high aspect ratio. Because of this high aspect ratio, a large flow- wetted surface area may be provided, with a relatively shorter flowpath length. Flow -wetted surface area may be a better metric for approximate comparison of polymer degradation performance of various rib structures, provided that both are similarly structured to provide approximately equal velocity over the full flow-wetted surface area and include effective alternating sections of smaller and larger cross- sectional area for flow.

[0028] The number of ribs intersected by a plane starting at a central axis may be from 1 and higher, such as 2, 5, 10, 15, 20, 30, or higher.

[0029] The number of flowpaths may be at least one. Frustoconical ribs between a pair of disc may form one flowpath. Spiral or labyrinthine ribs may form at least two flowpaths, one at the root and crest of each rib. If a multi-start spiral or labyrinth is used there may be any even-number of ribs.

[0030] The water injection flow control device may comprise an outer housing or cover containing the stack. The outer housing may be dimensioned to maximum water injection pressure. The outer housing may define the bore, either directly, or in some cases indirectly in an embodiment that may use an inner stationary sleeve which the moving disc translates within. The bore may be cylindrical. The moving disc may have an approximately cylindrical interface with the bore, however this is not intended to be a limiting feature, for example an oval, or polygonal bore shape may be used with a corresponding interface shape of the moving disc. The stationary disc may have an outer profile of any shape, and the term “disc” is used for simplicity; the outer profile shape of the stationary disc may have any geometric shape that supports the rib structure. The inlet and outlet may be in one end cap and therefore the outer profile of the stationary disc comprises a gap for fluid flow between it and the bore; however, in alternate embodiments the stationary disc may be tight or sealed within the bore and an inlet / outlet may be provided through the sidewall of the bore (not shown in figures).

[0031] The device may be dimensioned to drop the pressure up to 30 bar, more preferably 40 bar, even more preferably up to 50 bar or 100 bar or 200 bar or more, most preferably up to about 50 bar for many embodiments, with a flow rate in the range of 1 to 10, or 20 gallons per minute. The flowrate when full open in a position with the intermeshing ribs substantially disengaged may be a higher value exceeding 30 gallons per minute as the valve provides negligible flow resistance in a full open configuration.

[0032] The variations in cross-sectional may not be symmetrical, for example the cross-sectional area may be varied in only one dimension as shown in the accompanying figures, however this is not meant to be limiting, as variations could be made symmetrically in the opposing walls of the rectangular cross-section, and it is theoretically possible to include variations in the 3 or 4 walls defining the flowing cross-sectional area. The cost of manufacturing a device with such complex variations in flow area may not be justified by any potential performance or reliability benefits.

[0033] The cross-sectional area for flow of each flowpath may be smaller than the cross- sectional area of the inlet and outlet, which may have cross-sectional area equal to or larger than a nominal flow cross-sectional or nominal bore for pipes or tubes upstream of the device. The flowpath cross-sections in sum can be equal to the cross-sectional of inlet and / or outlet channels, for example as specified in WO 2014 / 178723 Al, or smaller. In some embodiments, and in some valve positions, the cross-sectional area of the flowpath may be larger than the cross-sectional area of each of the inlet and outlet. The cross-sectional area of the flowpaths in a device of the present disclosure may be in a range 200-0%, or 150-0%, or 100-0%, or 50-0% of a nominal bore upstream, dependent on the position of the valve.

[0034] Preferably, for a spiral or labyrinthine rib structure the entrance and exits of the at least two flowpaths may be arranged opposite (e.g. at or near to 180°) relative to one another in order to minimize bending loads on the discs, and pressure drops formed within the clearance seal area between intermeshing ribs which divides the flowpath at the root of a rib from the flowpath at the crest of the same rib. For the purpose of minimizing bending loads on the discs, spiral or frustoconical rib structures maybe preferable as they provide a natural symmetry about the axis of the pressure gradient within the flowpath. Labyrinthine shaped rib structures do not naturally provide this natural symmetry of pressure gradient within the flowpath, which may result in asymmetrical loading on the disc or ribs, and this asymmetrical load may cause binding through contact at the interference of the rib structures on one another, or the moving disc within the bore.

[0035] An axially moveable valve positioner may be used to control the position of a moving disc, which controls at least the cross-sectional flow area of a primary flowpath. The length of a primary flowpath may also be changed by axial positioning of a moving disc. The valve positioner may be controlled by any manner of linear actuator as is known in the art. The valve positioner may be controlled by a non-rotating stem that passes through a pressure seal packing element. The positioner may be attached to a hand wheel actuator, electrical / pneumatic / hydraulic actuator, or a pilot-controlled hydraulic actuator, or a combination of a pilot-controlled hydraulic actuator with a hand-wheel over-ride. The axially moveable valve positioner may be rigidly connected to a moving disc or a moving disc may float relatively to a valve positioner where an auxiliary flowpath is formed at the interface between a moving disc may and a valve positioner. Other actuators may be used.

[0036] The device may be made of suitable material. Parts of the device of the present disclosure may be made out of polymer or composite material, instead of steel or other metal, if the forces acting on the device and parts thereof permit. For example, the discs and / or rib structures can be made of plastic, polymer or composite material. Ribs may be made by machining / milling / grooving, molding, such as injection molding, casting, 3D printing, or otherwise. Rib structures of a non-metallic material supported by metallic discs, represent preferable embodiments of the present disclosure. The forces on each rib may be relatively low due to pressure being dropped over many ribs, and therefore non-metallic materials may provide sufficient strength and stiffness, while providing preferential properties regarding solids handling (allowing embedding of particles), corrosion, and low-friction.

[0037] For a spiral or labyrinthine rib structure, the pressure difference between flowpaths formed at the root and the crest of each rib may be relatively small (approximately DP=DP valve / (number of turns * 2), although such may be higher than this approximation towards the OD of the valve where each turn has a longer flowpath). Leakage may occur between intermeshing ribs, which may be an intentional part of the design, and may be at a sufficiently low shear rate such that it does not negatively affect the degradation performance. The structural loading is similarly small (approximately DP=DP valve / (number of turns), although it may be higher than this approximation towards the OD of the valve where each turn has a longer flowpath). Because the structural loading generally imparts a hoop load instead of a cantilever bending load, it may be possible for the intermeshing ribs to be made of polymer or composite material with a small thickness (in the range of 0.08” to 1”), or if metal is used the thickness may be as low as 0.02”. Using thin and tall rib structures may improve the polymer degradation performance of the valve, while reducing the cost, size, and weight. In addition to polymer injection application, this low cost valve may be used for water injection.

[0038] This document also provides a water injection system, comprising: a water injection pump and a polymer mixing station operatively coupled to a water source, for mixing polymer into the water and pumping the mixture; two or more injection wells operatively connected, one or more injection wells having a lower pressure than a highest pressure injection well.

[0039] This document also provides a water injection system, comprising: a mechanical- hydraulic controller which uses injection fluid as a working fluid, connected to the valve positioner, used to automatically limit the maximum injection pressure of an injection control valve to a predetermined setpoint. The mechanical-hydraulic controller uses regulators in a pilot circuit to limit the injection pressure (the pressure downstream of the valve) to a maximum of a setpoint.

[0040] Each of the water injection valves and the water injection system of the disclosed embodiments can include any feature as here described or illustrated, in any operative combination, each such combination is an embodiment of the present disclosure.

[0041] In various embodiments, there may be included any one or more of the following features: The flow control valve is structured such that adjustment to the axial position of the moving part, in use, adjusts a cross-sectional flow area of the primary radial flowpath. The inlet is operatively coupled to either a radially inner end or a radially outer end of the primary radial flowpath. The outlet is operatively coupled to the other of the radially inner end or radially outer end of the primary radial flowpath. The flow control valve is structured to balance pressure across the moving part via an auxiliary flowpath. The auxiliary flowpath is connected to the primary radial flowpath. The radially inner portion of the auxiliary flowpath connects to the primary flowpath at a predetermined location between the radially inner and radially outer ends and is structured to have less resistance to flow relative to the radially outer portion. At least the moving part defines the auxiliary flowpath. The moving part and the internal bore collectively define the auxiliary flowpath. The auxiliary flowpath comprises a radially inner portion and a radially outer portion. The radially outer portion is defined between the moving part and the internal bore. The radially inner portion is defined between the moving part and the valve positioner. The auxiliary flowpath is defined at an interface between the valve positioner and the moving part. The interface between the valve positioner and the moving part is defined by a high-angle shoulder of the valve positioner that is structured not to bind in the event that the moving part comes into physical contact with the valve positioner. The high-angle shoulder may have an angle between 30 and 90 degrees measured from the centerline. The interface between the valve positioner and the moving part includes at least one low-angle tapered surface. The interface between the valve positioner and the moving part has an axial length greater than 0.5”. The interface between the valve positioner and the moving part defines an angle from a central axis of the flow control valve of between 0.01 and 45 degrees. The valve positioner and moving part define an undulating surface along the axial length of an interface between the valve positioner and the moving part. The radially inner portion is structured to have less resistance to flow relative to the radially outer portion. The inlet or the outlet is defined through a central hole of the seating part. The inlet and the outlet are defined within an end cap of the housing. The primary radial flowpath is structured to have a length that is greater than a radius of the moving part. The primary radialflowpath is structured to be one or more of spiral, labyrinthine, or radial at an angle less than 90 degrees from an axis of the flow control valve. The seating part is dimensioned to have an outer radius that is smaller than an inner radius of the internal bore of the housing by at least a radial clearance of 0.050” for at least half of a circumferential distance along a perimeter of the seating part. An outer diameter of the moving part is smaller than the internal bore of the housing by a radial clearance of between 0.001” and 0.020”. Along a portion of an interface between the internal bore and moving part, one or both of an outer surface of the moving part and the internal bore has one or more of: an undulating surface along its axial length; an undulating surface along its circumferential length; or a labyrinthine or spiral flowpath. The labyrinthine or spiral flowpath is formed by split guide rings of the moving part. Gaps in the split guide rings aligned at a position around a perimeter that is approximately opposite the adjacent guide rings. An outer surface of the moving part comprises axial grooves to create an undulating surface for circumferential flow in the outer auxiliary flowpath formed between guide rings of the moving part. The moving part and the seating part are structured to undulate in shape along at least a portion of a length of the primary radial flowpath. An undulating surface of one or both the moving part and the seating part is defined at least at a crest of intermeshing ribs that are spiral or labyrinthine, with the undulating surface defining peaks and troughs, with at least one set of troughs aligned radially, such that at an open position a radial flowpath is formed through the radially aligned troughs, while crests of the ribs remain in an overlapping position to maintain alignment between the moving part and the seating part. A length of the primary radial flowpath is between 12” and 3000”. A thickness of each intermeshing rib is between 0.030” and 1.000”. An inner diameter of the internal bore is between 3” and 20”. The moving part and the seating part comprise a pair of discs. The flow control valve has two or more pairs of discs arranged in parallel or series with the moving part of each pair of discs is structured to be controlled by the valve positioner in use. A mechanical-hydraulic controller is connected to operate the valve positioner. A filter, strainer, or screen is upstream of the primary radial flowpath or in pilot hydraulic fluid piping to the fluid control valve to prevent plugging in a restriction or a regulator. The intermeshing ribs form two or more primary radial flowpaths in parallel. The valve positioner is connected to adjust the resistance to flow within the two or more primary radial flowpaths. The flow control valve is structured to permit a degree of non-zero leakage between the two or more primary radial flowpaths. The two or more primary radial flowpaths are offset from each other to minimize the differential pressure between the two or more primary radial flowpaths. The flow control valve is structured such that during use a pressure on a back side of the moving part is at or near to a pressure in the primary radial flowpath. One or both the moving part and the seating part are structured to provide an undulating surface along at least a portion of the length of the primary radial flowpath to create a gradual and repetitive contraction and expansion of a cross-sectional flow area of the primary radial flowpath. One or both the valve positioner or an actuator of the valve positioner is rated for an axial force lower than the potential force that would be generated if the valve positioner were rigidly connected to the moving part. The interface between the valve positioner and a moving disc includes intermeshing ribs to increase the length of the flowpath at this interface, which may include flowpaths that are spiral, labyrinthine, or radial at an angle less than 90 degrees fromthe centerline. During assembly, a stationary disc is coupled to an end cap using a threaded fastener that is tightened while a moving disc is positioned in the bore and while the ribs of a moving disc are intermeshing with the ribs of a stationary disc. The primary radial flowpath is defined by radiused corners. The housing is cylindrical. The moving part has a cylindrical side wall. The stationary or seating part has a cylindrical side wall. The moving part is connected to float relative to the valve positioner (i.e. the moving part is not rigidly or directly connected to the valve positioner). The polymer flow control valve with a hydraulic control system which includes a restriction, the restriction being used to control the flow rate through the hydraulic system while creating minimal polymer degradation, such as a coiled tube with a diameter less than 0.25”. Using the flow control valve to limit a maximum pressure downstream of the flow control valve via a hydraulic control system which is supplied by the same viscous injection fluid as the flow control valve.

[0042] The foregoing summary is not intended to summarize each potential embodiment or every aspect of the subject matter of the present disclosure. These and other aspects of the device and method are set out in the claims.

[0043] BRIEF DESCRIPTION OF THE FIGURES

[0044] Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:

[0045] Fig. 1 A is a cross-sectional view of a flow control valve. Fig. IB is a cross-sectional view of the flow control valve of Fig. 1A in a closed position. Fig. 2A is a cross-sectional view of another embodiment of a flow control valve. Fig. 2B is a cross-sectional view of the flow control valve of Fig. 2A in a fully -open position. Fig. 3 A is a cross-sectional view of a valve positioner with a fluted disc puller. Fig. 3B is a cross-sectional view of a flow control valve configured for an inside-out flow direction, in a partially -open position. Fig. 4A is a cross-sectional view of a flow control valve with an inner auxiliary flowpath at an interface between the moving part and the valve positioner. Fig. 4B is a cross-sectional view of a flow control valve with an inner auxiliary flowpath with a ribbed interface. Fig. 4C is a cross- sectional view of a flow control valve with a rigidly connected valve positioner and an inner auxiliary flowpath at a predetermined location within the primary flowpath. Fig. 4D is a cross-sectional view of a flow control valve with a rigidly connected valve positioner and an inner auxiliary flowpath at a central location with a predetermined flow resistance. Fig. 4E is a cross-sectional view of a flow control valve with an inner auxiliary flowpath connecting to a primary flowpath at a predetermined location. Fig. 4F is a cross-sectional view of a flow control valve with an inner auxiliary flowpath connecting to a primary flowpath at a predetermined location. Fig. 5A is an isometric cross-sectioned view of an intermeshing rib structure that changes flowpath length with axial movement. Fig. 5B is an isometric cross-sectioned view of an intermeshing rib structure that changes flowpath cross-sectional area and length with axial movement. Fig. 5C is an isometric cross-sectioned view of an intermeshing rib structure with undulations and tapered ribs. Fig. 5D is an isometric cross-sectioned view of a spiral intermeshing rib structure that changes flowpath cross-sectional with axial movement. Fig. 5E is an isometric cross-sectioned view of a labyrinthine intermeshing rib structure that changes flowpath cross-sectional with axial movement. Fig.5F is an isometric cross-sectioned view of an intermeshing rib structure with undulations at the crest. Fig. 5 G is an isometric cross-sectioned and wire-mesh view of an intermeshing rib structure with undulations at the root. Fig. 5H is an isometric cross-sectioned view of an intermeshing rib structure with undulations in the rib thickness. Fig. 6A is an isometric wireframe view of a moving disc outer surface with guide rings having gaps offset 180 degrees. Fig. 6B is an top plan wireframe view of a moving disc outer surface with guide rings having gaps offset 180 degrees and longitudinal grooves. Fig. 7 is a cross- sectional view of a multistage flow control valve, having outer sleeves and a hollow valve positioner. Fig. 8 is a schematic of a pair of flow control valve with a mechanical-hydraulic injection pressure limiter. Fig. 9 is a section view of a valve with a mechanical-hydraulic injection pressure limiter.

[0046] DETAILED DESCRIPTION

[0047] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

[0048] Features and their benefits are only discussed in detail for the first figure for which they are shown. In general, the complexity of embodiments increases sequentially through the Figures and for the sake of clarity and brevity. In order to understand the configuration and benefits of features shown in certain figures, it may be necessary to read the entire description to that point and applying the understanding of features, configurations, and benefits from previous Figs, into the reading of subsequent figures.

[0049] The terms “connect”, “connected”, “couple” or “couples,” as used herein are intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection such as a shaft, flange or weld connection, or through an indirect electrical or hydraulic connection or via other devices and connections.

[0050] The term “polymer” is used to refer to both the polymer chains which may be dispersed with an aqueous solution, and also to the aqueous solution itself. “Polymer injection” and “water injection” may be used interchangeably. Polymerized fluid forms a gel fluid structure.

[0051] The term “valve” is used to refer to the device of the present disclosure which does not necessarily close, and whose main function is that of a flow regulator or choke.

[0052] The term “ribs” is used to refer to intermeshing ribs that form a flowpath between a pair of discs, this flowpath being changed by axial movement of a disc.

[0053] The term “disc” is used to refer to a structure comprising intermeshing ribs. In the most pragmatic form the discs are generally cylindrical in structure, however this is not a necessary feature, and the discs need not have flat nor parallel ends, nor is it necessary for the outer surface profde to be circular. The disc may comprise multiple parts coupled together, with some potential configurations illustrated in the figures.

[0054] The term “internal bore” and “bore” are used to refer to the cavity defined within the housing (or within a structure in the housing), having a suitable cross-sectional profile such as a circle, ellipse, prism, polygon, regular, symmetrical or other shape which forms an interface with a moving disc.The bore may be any prismatic shape. The bore may include a draft of less than 2 degrees (e.g. not a perfect prism), without departing from its definition.

[0055] The term “nozzle” is used to refer to a location of a valve where it may be connected to a piping system, which may be either an inlet or an outlet. The term does not imply a restriction or acceleration of the flow.

[0056] Adjustable devices for controlling the flow rate of polymer solutions are known from U.S. Pat. 4,276,904, which describes an inlet and outlet manifold with a plurality of helical tubes separating the manifolds. Each tube has a unique length or internal diameter to allow for a limited number of discrete control settings for pressure drop across the valve. The valve design may provide acceptable shear rate performance due to the ability to use long tubes to reduce the rate of energy transfer across the valve, however due to the size of the valve and limited resolution in control its useability is limited.

[0057] A more compact device with increased resolution for pressure regulation of polymer solutions is known from U.S. Pat. 3 ,477 ,467 A, which describes a plurality of parallel flow conduits which contain a length of packed solids which may be adjusted. Such a device is cumbersome to operate as control of the packed solid length is difficult to control.

[0058] U.S. Pat. 4,510, 993 A proposes a polymer control valve with a tapered or pointed flow control element such as a long needle valve with matching profile to provide an increased flow length for pressure drop. While simple and easy to operate, such a device provides a relatively short flow length compared to other polymer control devices and compromised polymer degradation performance.

[0059] A positive displacement flow device such as a gear pump is known from U.S. Pat. 4,617,991 A. The positive displacement motor may be connected to a variable load bank which allows for control of fluid rate and pressure through the device. This device results in sub-optimal polymer degradation performance due to rapid energy transfer to the polymer through the device.

[0060] Pressure reduction devices for polymer solutions using piping containing alternating patterns of contraction and expansion chambers are known from U.S. Pat. 4,782,847 and WO 2015 / 092334 A2, which describe repetitive sections of piping with reduced ID causing fluid acceleration followed by sections of increased ID resulting in fluid deceleration. An alternating pattern of contraction and expansion chambers has been found to result in reduced polymer degradation at similar pressure drops as piping with a continuous ID. These devices are limited their usability for polymer control due to limited resolution for control and excessive space requirements associated with achieving long flow lengths with straight piping. A similar drawback is observed with WO 2012 / 001671A2, which describes adjustable flow areas through straight piping without contraction and expansion chambers.

[0061] Various fluid control valves have been proposed in the prior art, that use extended channel flow lengths with variable geometries that are known to reduce the rate of energy transfer, cavitation and noise. U.S. Pat. 4,279,274A describes a cage valve used to control fluids under high pressure where an axial stack of discs with a plurality of slotted annular baffle ribs provide a series of interconnected passageways resulting in restricted orifices and expansion areas passing through the valve. Similarly, U.S. Pat. 3,514,074, US 2003 / 0188787, WO 2014 / 178723 Al, US 2005 / 252559 Al and WO2017 / 105250 describe plug and cage valves with an axial control member and stacked annular disks providing various spiral and labyrinthine profiles. A spiral fluid pathway containing contraction and expansion areas is described by US 2005 / 252559 Al, and subsequently by WO 2017 / 105250. These plug and cage valves with stacked annular disks are reasonably compact, and provide good polymer degradation performance due to the long flowpaths achievable. The biggest issue with these valves is that their control members are not pressure-balanced, requiring significant actuation force to function the valve and also limited resolution in control, with the number of set points corresponding to the number of stacked annular disks in the valve. To allow for high resolution in control a significant number of stacked disks are required significantly increasing the size, cost, tendency to plug, and complexity of the valve.

[0062] A disc which is axially moveable relative to a positioner is described in U.S. Patent publication Nos: 4,258,750 and 4,473,210. The disc is connected to cylindrical intermeshing members and intended for applications with high pressure with the objective of reducing the acoustic energy generated by the turbulence which creates objectionable noise. This patent describes a valve that in a closed condition allows the actuator (stem) to be forced against the action of a spring to obtain a positive seal between a member connected to the actuator and a seat. While in this closed position, “high pressure fluid will leak from the inlet passage to the volume of the web above the valve plug” (which is analogous to the backside of a moving disc) “to tend to hold the valve in a tight, closed condition”. It further describes that in the operation of opening the valve, “the stem is raised and the action of the spring and slidable connection between the collar and stem will permit the stem to move relative to the valve seat thereby providing fluid communication between the upper and lower surfaces of the valve plug through the openings”. Here it is critical to note that the openings are shown at a location connecting to the center of the primary flowpath. The author correctly describes that: “this will initially release the high pressure above the valve plug to permit an easier opening of the valve”. While a central passageway as described in this prior art may allow a valve to be more easily opened off a valve seat of a large diameter, it does not automatically achieve a balanced hydraulic force across the valve plug (moving disc) in an open operating position. The author goes on to state that: “eventually, the pressure differential between the upper and lower surfaces of the valve plug will hold the plug in a semi-balanced condition for an effective valve action”. While the semi-balanced condition discussed in this prior art may be adequate for a valve plug with a relatively low surface area (as may be inferred from the drawings, in particular the relatively small diameter difference between the stem and the valve plug) used for high pressure noise-reduction applications, it does not achieve a truly balanced condition that may be necessary for an easy actuation of a polymer injection valve. A further deficiency of this prior art valve design in regards to a polymer injection application, is that no active circulation of the fluid on the backside of the valve plug is provided and the static fluid in this cavity may lead to polymer biological degradation, plugging, and corrosion problems. For further clarity that a circulating flowpath to the backside of the valve plug is not considered or anticipated by this prior art, please observe Fig. 7 label 114 which points to an outer surface of a valve plug; the leader line points in the near proximity to a groove which may be used to install an O-ring and effect a seal. There is no teaching about how toproperly balance a moving disc. Rather than using an auxiliary flowpath to achieve hydraulically balancing pressures, this patent describes that “A coil spring acts against the washer and an internal shoulder of the valve plug, whereby the spring urges the valve surface away from the valve seat when the valve is in an opened condition”. If a spring acts with a force, it requires that the hydraulic forces on a valve plug be unbalanced. Furthermore, this prior art does not describe how a design may achieve a semibalanced condition in an open position except for an inner flowpath with a spring member. A balancing cylinder is shown, but its function is not described. Under certain conditions, the semi-balanced condition that the author claims, may actually be achieved because the balancing cylinder has a diameter which is smaller than the outer diameter of the intermeshing cylinders. A balancing cylinder as shown may be attempted to be designed to provide a balanced condition, but in reality the diameter can never be perfectly correct to achieve a balanced condition over a range of valve positions and fluid properties. A potential issue with a balanced cylinder designed in this manner is that it sets up a positive-feedback dynamic where compressibility of the spring and the fluid in the upstream and downstream piping ultimately results in a vibration or oscillation in the axial position of the valve plug without an effective damping mechanism. Oscillations may quickly wear out valve components or damage other parts in the system. The balancing cylinder design also requires additional length of the valve plug and ultimately the valve. Another issue with a design having seals, such as an O-ring in a groove as shown in the balancing cylinder of this prior art, is the friction at the seal interface, and valve positioning is more likely to be unpredictable due to stiction (e.g. static friction).

[0063] A diaphragm which is pressure-balanced using an auxiliary flowpath is described in U.S. Patent publication No: 4,003,548. A moving disc is not considered. Intermeshing ribs are not considered. An equivalent to a primary flowpath is formed by a diaphragm against a planar surface. The primary flowpath is considered to be only in either an open or closed state, consistent with the intended function as a regulator of gas outlet gauge pressure. This prior art does not consider service in a liquid or polymer solution or well injection application. A secondary bore (between parts labelled 13 and 15) is of a different diameter than the diaphragm which forms the primary flowpath. A restriction to flow is not considered to be formed at the interface (longitudinal grooves 13a).

[0064] Embodiments of the present disclosure may improve upon one or more of the limitations and issues of the prior art described above: (1) a balancing cylinder bore is not required, (2) a seal is not required, (3) damping is provided, (3) short duration pressure fluctuations (from the upstream or downstream piping system dynamics) create pressure forces on a moving disc in a direction that does not create positive-feedback.

[0065] Figures are shown in an intuitive and conventional configuration with the actuator on the top of the page. However, this may create a challenge with air or gas filling the space on the backside of the moving disc. Gas filling the space on the backside of the disc may increase the compressibility of the volume and may lead to oscillations in the moving disc position or fatigue loading on the actuator. In order to mitigate this challenge it may be necessary to include an air purge valve (not shown in any of thefigures), or to mount the valve in an orientation with the moving disc below the stationary disc in order to automatically purge gas from backside and avoid any potential for gas buildup to occur.

[0066] In some cases the primary flowpath(s) may remain open at any valve position, whether fully closed or open. For example, in some cases the primary flowpaths are never blocked by a plunger - the only state where flow through any of the primary flowpaths ceases may be in a fully closed position where the valve may be sealed by a feature towards the end of a valve positioner.

[0067] Referring to Fig. 1A, a flow control valve 10 is illustrated. The valve 10 may have a housing 58 with an inlet, an outlet, and an internal bore 50. The valve 10 may have an outer nozzle 53 and an inner nozzle 52. In the embodiment shown, the outer nozzle 53 is the inlet and the inner nozzle 52 is the outlet. The valve 10 may have a moving part (such as moving disc 30) and a seating part (such as stationary disc 20) that have an intermeshing rib structure 14. The discs may collectively define a radial primary flowpath 12 from the inlet to the outlet. A moving disc 30 controls the resistance to flow, in order to regulate or choke the flow, through the device via primary flowpath(s) 12. A moving disc may comprise ribs 18 that may intermesh with ribs 16 of a stationary disc. The moving part may be mounted to axially translate, relative to the seating part, within the internal bore of the housing, to adjust a resistance to flow within the primary flowpath. A valve positioner 40 may be connected to adjust an axial position of the moving part. The position of the moving disc changes either the length or cross-sectional area (or both) of the primary flowpath(s) formed between a pair of discs by the intermeshing ribs. The embodiment of Fig. 1A shows a high aspect ratio (tall and thin) ribs structured in a spiral. A flowpath may be formed towards the crest of a rib, and a second flowpath may be formed towards the root of a rib. Fig. 1 A has discs each with a single long spiral rib and two primary flowpaths 12 are formed. The primary radial flowpath or flowpaths may be structured to have a length that is greater than a radius of the moving part, or another suitable length. Each disc may be integral, as shown in the stationary disc 20, or a disc may be formed by multiple coupled parts, as shown in the moving disc 30. The moving disc 30 may comprise a thick backing plate 31 to minimize deflection and bending, which may be joined to intermeshing ribs 18 by suitable manufacturing methods as are known in the art, which may including bonding, adhesives, brazing, welding, and may be mounted within a groove of the same shape. Intermeshing spiral ribs may be made of suitable materials, such as sheet material (plastic composite or metal) that is mandrel wound together with a removeable spacer material to provide the required clearance. Polymer or composite materials may also be used to manufacture discs and / or rib structures. Ribs may be made by machining / milling / grooving, molding, such as injection molding, casting, 3D printing, or otherwise.

[0068] The flow control valve 10 may be structured to balance pressure across the moving part. An outer and / or inner auxiliary flowpath may be defined by the valve 10. The flow control valve may be structured to balance pressure across the moving part via an auxiliary flowpath. The moving disc may define an outer surface 39 that forms an outer auxiliary flowpath 54, for example between surface 39 and the bore 50. In this embodiment the bore 50 may be formed by the inner surface of a housing 58, however, this is not a necessary feature, as a sleeve or other structure within the housing 58 may be usedto form a bore for a moving disc to move within (one example is the sleeve used in Fig. 7). The auxiliary flowpath may comprise a radially inner portion flowpath 34 and a radially outer portion flowpath 54. The radially outer portion may be defined between the moving part and the internal bore. The radially inner portion may be defined between the moving part and the valve positioner. The moving disc may define an inner auxiliary flowpath 34 formed between it and the valve positioner 40. The valve positioner may comprise a shoulder, such as a high-angle shoulder 36 at the interface between the valve positioner and the moving disc. The interface between the valve positioner and the moving part may thus be defined by a high-angle shoulder of the valve positioner that is structured not to bind in the event that the moving part comes into physical contact with the valve positioner. In some examples, the interface between the valve positioner and the moving part has an axial length greater than 0.5”. A purpose of a high-angle shoulder may be to prevent binding in the event that the valve positioner 40 contacts the moving disc 30. The interface between the valve positioner 40 and the moving disc 30 may be defined by an axially overlapping and low angled portion 38. There may be at least two function of a low-angle and overlapping portion 38: (1) to reduce degradation of the polymer that travels through the auxiliary flowpath 34, and (2) to allow the valve positioner 40 to be rapidly actuated towards a closed position at low force. The interface between the valve positioner and the moving part may include at least one low- angle tapered surface.

[0069] For further explanation of the above point (2): hypothetically, if the interface between the valve positioner 40 and the moving disc 30 comprises only a high-angle shoulder 36, then these surfaces may come into contact during any actuation of the valve towards a closed position when the closing velocity of the valve positioner 40 exceeds the rate which fluid can pass the outer auxiliary flowpath 54 divided by the cross-sectional area of the moving disc backside 32 caused by the movement of the moving disc 30 in the closing direction; a sufficiently strong actuator or operator would be able to draw a vacuum, however the forces required may be impractical (for example a valve with a 10 inch bore operating at 2000 psi injection pressure may require over 150,000 pounds force to close quickly). Depending on the flowrate through the outer auxiliary flowpath 54 and the cross-sectional area of the moving disc backside 32 actuating of the valve position by 5% in the closing direction may take several minutes with a reasonable amount of applied force. While such slow actuation rates are acceptable for the system and automated valve controller, it is likely that manually actuated valves would be frustrating for an operator. The low angle and overlapping portion 38 at the inner auxiliary flowpath 34 allows the valve positioner 40 to be closed at a high velocity over a reasonably short distance at low force, and then allows for the moving disc to ‘catch up’ over time as pressure in the backside 32 equilibrates.

[0070] Valve positioner 40 may be moved by an actuator assembly 60. Figures throughout show a manual actuator, but the reader may understand that any linear actuator as is known in the field may be used. A packing seal 62 prevents leakage where the valve positioner 40 penetrates the end cap 56. Because of the potentially large forces or impacts that could be generated by the large moving disc, it may be desirable to use an actuator with axial compliance (e.g. springs or bumpers), which are not shown but can be incorporated into the actuator.

[0071] The stationary disc 20 is sealed to the end cap using an O ring in a groove 26 at a diameter that balances hydraulic forces on the stationary disc 20 in order to reduce the bending and distortion of the disc. Distortion of a disc may undesirably result in interference between intermeshing ribs leading to actuation problems. The inlet and the outlet may be defined within an end cap of the housing, or just one of them. The stationary disc 20 may be coupled to the end cap 56 using a retention fastener 24. While a single hollow nut is shown as the retention fastener 24 installed from the inside, the reader should understand that the direction of this fastener may also be installed from the outside, or that a bolt pattern, or various other fastener designs could also be used. A seat profile 28 for a positive closing seal may be integral with the retention fastener 24. The stationary disc 20 may be integral with an end cap 56. The inner nozzle 52 may be central to the stationary disc 20, however inner nozzle 52 is not necessarily located at the centerline of the disc nor the centerline of the end cap 56. The end caps 56 and 57 are considered part of the housing 58 and may be coupled with techniques known in the field. The nozzle-end end cap 56 is shown with a fillet welded connection, and the actuator-end end cap 57 is shown with a threaded connection and an O ring seal. Alternatively, end caps may be coupled using tie rods, flanges, or other coupling techniques.

[0072] The seating part and moving part may have suitable dimensions. The seating part (disc 20) may be dimensioned to a suitable size, for example to have an outer radius that is smaller than an inner radius of the internal bore of the housing by at least a radial clearance of 0.050” for at least half of a circumferential distance along a perimeter of the seating part. An outer diameter of the moving part may be smaller than the internal bore of the housing by a radial clearance of between 0.001” and 0.020”.

[0073] The nozzle couplers are illustrated a threaded coupler at the outer nozzle 53, and a studded-flange coupler at the inner nozzle 52. However, any variety of couplers may be used, and it may be preferable for ease of integration with common piping designs for a 90 degree elbow to be welded at each of the nozzles (not shown) in order to provide a straight pipe run through the valve.

[0074] Referring to Fig. IB, a valve 10 is shown in a fully closed position. A distal end of a valve positioner 40 seals against a seat profde 28. The primary flowpaths 12 are reduced to a very small cross-sectional area but are not sealingly closed. The faces of the high angle shoulder 36 may or may not be touching in this position. Because of the clearances required for axial movement of the ribs, it is very challenging or impossible to form a reliable seal within the primary flowpaths. And it may also be important that the primary flowpaths don’t close fully for the following reasons: 1) a gap is necessary for solids or debris tolerance - the gap provides a space for solids to move into when the primary passageways are brought to a very small cross-sectional area, 2) to avoid hydraulically locking the valve in a closed position with almost the full cross-sectional area of the moving disc 30 potentially acting in a closing direction on itself in the event that a high angle shoulder 36 was sealing and the primary flowpaths were sealing towards an outer diameter, and 3) practically the tolerances would be hard to achieve. The same seal location may be used regardless of the flow direction through the valve.

[0075] Referring to Fig. 2 A, a valve 10 is shown with frustoconical shaped intermeshing ribs 16, 18 forming a single primary flowpath 12. Primary flowpath 12 may be longer than the radial distancebetween a disc’s ID and OD, and follows a low-angled path back and forth from OD to ID. In order to provide an approximately equal peak velocity throughout the undulating primary flowpath 12, the taper angle on the intermeshing ribs is higher towards the center, and lower towards the outer edge. The intermeshing ribs may be thicker at their root towards the center corresponding to a higher taper angle. For the sake of this discussion the flowpath (which actually has a cross-sectional perpendicular to the flow direction which is an conical annulus) will be simplified as having a height (which is approximately equal to the perimeter), and a width (which is approximately equal to the gap between intermeshing ribs). Undulations may be formed in the outer generally frustoconical surface of the intermeshing ribs. Relative to the flow direction the undulations have a diverging angle and a converging angle. A converging angle may be lower than a diverging angle to maximize valve performance. In a general sense valve performance is measured by low polymer degradation at conditions with high pressure drops and intended / high flow rates. Valve performance may be achieved by providing a sufficient number of approximately equal acceleration and deceleration stages (undulations), with flow structured in a manner to avoid polymer chain breakage. Rate of acceleration (convergence angles) is known to be more important than the rate of deceleration (divergence angles). The undulating profile may be rounded / filleted at the restriction formed by each undulation. It may be preferable for each restriction to be short in length. The taper angles of the intermeshing ribs may be selected to provide a constant velocity at every engaged undulation, at any valve position. It may instead be preferable to design the intermeshing ribs to provide a lower velocity towards the OD, or a higher velocity towards the OD as determined by empirical testing in order to optimize performance. In order to provide a perfectly uniform velocity throughout the valve, the shape of each rib may actually have a curved cross-sectional (e.g. more of a toroidal surface than a pure frustocone), although the small changes of angle would be hard to see at a drawing of this scale. The undulations of an outwardly positioned rib may be smaller amplitude and wavelength as compared to the undulations of an inwardly positioned rib; the amplitude and / or wavelength of undulations at a given rib position may be proportional to the flowpath width; where the flowpath is wider towards the ID, therefore the undulations may also be longer and taller towards the ID. The undulations towards a root of a rib may only be engaged at certain valve positions towards the closed position; therefore, it may be preferable for these undulations towards the root of each rib to have a lower amplitude and wavelength (since they will only be engaged at valve positions where the flowpath width is small).

[0076] Referring to Fig. 1 A, the valve positioner and moving part may define an undulating surface along the axial length of an interface between the valve positioner and the moving part. With the low angle taper portion 38 of the valve positioner 40 as shown, the flow direction may be from outside in similar to Fig. 1 A. The outer surface 39 of a moving disc 30 may be undulating to create fluid acceleration and deceleration through the outer auxiliary flowpath 54.

[0077] The stationary disc 20 and moving disc 30 may be each formed by two separate pieces bonded together. Radial slots 70 at the interface between ribs 18 and a backing plate 31 of a moving disc 30, and radial slots 70 at the interface between ribs 16 and a backing plate 21 of a moving disc 20 ensurethat a downstream pressure is felt uniformly between the disc insert and the metal backing plate and help ensure the bond between the two is not broken.

[0078] Referring to Fig. 2B, the valve of Fig. 2A is shown in a fully open position. The ribs 13 and 18 are disengaged from each other and a direct flowpath from the OD to the ID is formed, no longer is fluid required to follow a primary flowpath 12. The primary flowpath 12 becomes inactive with the valve in a fully open position. The direct flowpath is not longer than a disc OD minus a disc ID. In this position the restriction and pressure drop for flow through a valve is minimal. The interface between the valve positioner and the moving part may define an angle from a central axis of the flow control valve of between 0.01 and 90 degrees.

[0079] Referring to Fig. 3 A, an alternate valve positioner 40 is shown with a fluted disc puller 42, which may allow a moving disc (not shown) to be retracted using the actuator (not shown). This may be a valuable feature for maintenance or disassembly or troubleshooting. The valve positioner still comprises a high-angle shoulder 36 and an axially overlapping and low angled portion 38. The fluted disc catcher may have a shoulder for contacting the moving disc and flutes that ensure fluid can bypass unrestricted, since fluid must bypass this location as the moving disc is retracted.

[0080] Referring to Fig. 3B, an alternate control valve 10 configuration is shown for a reversed direction of flow. The inner nozzle 52 is an inlet, and an outer nozzle 53 is an outlet. The valve positioner still comprises a high-angle shoulder 36, but this shoulder may be fluted as fluid must be allowed to bypass it if it comes into contact with a moving disc 20 in order to extend the moving disc towards a closed position. The axially overlapping and low angled portion 38 may have a reversed taper angle corresponding to the reversed direction of flow through the valve, which also reverses the direction of flow through the inner auxiliary flowpath 34 and the outer auxiliary flowpath 54 (reversed comparing to prior figures). The valve positioner may comprise two coupled members, such as by a threaded connection as shown. In this flow direction, and in a fully closed position the distal end of a valve positioner 40 may contact a seat profile 28, similar to prior figures, with the exception that in Fig. 3B that the seal is not pressure-assisted.

[0081] Referring to Fig. 4A, a simplified schematic is shown, illustrating a half-cross-sectional of a valve 10 with a configuration consistent with the previous figures. The inner auxiliary flowpath 34 may be formed at an interface between a moving disc 30 and a valve positioner 40 via a single long low angle tapered portion 38. The inner auxiliary flowpath 34 connects to a radially inner end of a primary flowpath 12.

[0082] Referring to Fig. 4B, a simplified schematic is shown, illustrating a valve 10 with intermeshing ribs forming the flowpath 34 between a valve positioner 40 and a moving disc 30. The intermeshing rib structure 14 may create an overlapping portion 38. Intermeshing ribs are shown as frustoconical ribs, but any pattern such as a spiral may also be used here. Intermeshing ribs perform the same function as the low angle taper of previous figures, except that intermeshing ribs may provide larger surface area and may provide an improvement in polymer degradation performance.

[0083] Referring to Fig. 4C, a simplified schematic is shown, illustrating a valve 10 with a moving disc 30 rigidly connected to a valve positioner 40, and an inner auxiliary flowpath 34 in hydraulic communication with a predetermined location 72 along a primary flowpath 12. The inner auxiliary flowpath 34 may be sized (large in cross-section) to provide less, for example substantially less, resistance to flow as compared to the resistance to flow of the outer auxiliary flowpath. The pressure on the moving disc backside may be similar to the pressure in the primary flowpath at the predetermined location. The predetermined location may be selected for balancing of hydraulic pressures to minimize hydraulic forces on the valve positioner.

[0084] A moving disc 30 may have a clearance inside a bore 50 similar to previous figures to create an outer auxiliary flowpath 54, or alternatively (not shown) the moving disc may be sealed in the bore 50 with a sliding seal, or with a membrane seal. If a seal is used between the moving disc 30 and the bore 50 then an outer auxiliary flowpath will not exist and there will only be a single auxiliary flowpath. In this embodiment fluid does not circulate through the space at the backside 32 of a moving disc 30, which may be problematic as static fluid in the backside space may lead to solids settling or dead leg bacterial corrosion, or other issues.

[0085] Referring to Fig. 4D, a simplified schematic is shown, illustrating a valve 10 with a moving disc 30 rigidly connected to a valve positioner 40, and an inner auxiliary flowpath 34 at a central location. The inner auxiliary flowpath 34 is sized such that the resistance to flow through it is a predetermined fraction of the resistance to flow of the outer auxiliary flowpath 54 in order to provide a pressure on the backside 32 of the moving disc 30 that balances the hydraulic forces to minimize hydraulic forces on the valve positioner. Undulations may be included in an inner auxiliary flowpath 34, as, shown to reduce polymer degradation. An outer nozzle 53 may be formed in a side wall of a housing 58, instead of being formed in an end cap as per previous figures.

[0086] Referring to Fig. 4E, a simplified schematic is shown, illustrating a valve 10 in which the inner auxiliary flowpath 34 is formed at an interface between a moving disc 30 and a valve positioner 40 via a single long low angle tapered portion 38. The auxiliary flowpath may be connected to the primary radial flowpath. The inner auxiliary flowpath 34 may connect to a primary flowpath 12 at a predetermined location 72 which is between the radially inner end and the radially outer end of the primary flowpath 12. The inlet may be operatively coupled to either a radially inner end or a radially outer end of the primary radial flowpath. The outlet may be operatively coupled to the other of the radially inner end or radially outer end of the primary radial flowpath. The connection point of the inner auxiliary flowpath 34 to the primary flowpath 12 must be at a location sufficiently towards the radially inner end of the primary flowpath 12 such that a backside pressure can be established to balance hydraulic forces across the moving disc. This maximum location will be a function of the pressure distribution within the primary flowpath (which is not necessarily linear along a radial line). A moving disc may include a seal profile to seal against a seat 28. A disc puller 42 profde may be required in this embodiment to allow the valve to be opened from a valve position if the direction of flow through the valve is from an outer nozzle 53 to an inner nozzle 52; because in this direction of flow, a hydraulic force across the seat 28 area will urge themoving disc in a closed direction, and this force must be overcome to allow the valve to be opened; once the valve is in an open position the moving disc begins floating again with location determined by the relative pressure drops of the auxiliary flowpaths. If the direction of flow through the valve is from an inner nozzle 52 to an outer nozzle 53 then a disc puller 42 may not be required. A disc puller 42 in this embodiment need not be ported as there is no flow bypassing it (the moving disc does not have a hole at the centerline). A drawback of this configuration is that the maximum pressure forces that can be generated across the moving disc are reduced. A benefit of this configuration is that the pressure drop through an inner auxiliary flowpath 34 may be reduced as compared to a configuration such as Fig. 4A, and this reduced pressure drop may translate into an improvement in polymer degradation performance for the fluid traversing the auxiliary flowpaths.

[0087] Referring to Fig. 4F, a simplified schematic is shown, illustrating a valve 10 similar to that of 4E. The inner auxiliary flowpath 34 connects to a primary flowpath 12 at a predetermined location 72 which is between the radially inner end and the radially outer end of the primary flowpath 12. The inner auxiliary flowpath 34 may comprise two portions, the first portion at an interface between a moving disc 30 and a valve positioner 40 via a single long low angle tapered portion 38, and a second portion through a passageway that connect to a primary flowpath 12. The first portion has a resistance to flow which may be changed based on the relative position of the moving disc and the valve positioner, and the second portion has a fixed geometry. The second portion may be formed by a passageway within the moving disc that is formed by drilled holes, or at the interface of separately manufactured pieces if the moving disc is manufactured from several pieces. The interface between a moving disc 30 and a valve positioner 40 may be of a smaller diameter than the predetermined location 72. A disc puller is not present in this figure.

[0088] Other embodiments, not shown, may locate the actuator at the stationary disc end of the valve. The valve positioner may penetrate and be concentric with the inner nozzle. Or the valve positioner may be eccentric with the inner nozzle. The valve positioner may be aligned with the centerline of the bore, and the inner nozzle may be offset to one side.

[0089] Referring to Fig. 5A, an alternate intermeshing rib structure 14 is shown in which cylindrical walls are used. A flowpath may be formed between the cylindrical surfaces of the ribs, and because the restriction within the flowpath is primarily formed by the flow in the axial direction, the cross-sectional area of the flowpath does not substantially change in response to axial movement of a disc. The flowpath length may change in response to axial movement of a disc. Rib structures presented in Figs. 5A thru 5H may be used in a primary flowpath or an auxiliary flowpath of a valve. This cylindrical rib structure may be advantageous for application in an auxiliary flowpath location where it may be desirable to affect only a small change in the flow restriction in response to a large axial translation.

[0090] Referring to Fig. 5B, an alternate intermeshing rib structure 14 is shown with frustoconical rib structures. For a discussion on this rib structure refer to the discussion of Fig. 2A. Thefrustoconical rib structure does not require undulations, as shown in Fig. 5B, both faces of each rib may be flat.

[0091] Referring to Fig. 5C, an alternate intermeshing rib structure 14 is shown with frustoconical rib structures and undulations 84 in the thickness of the ribs. The undulations 84 are preferably only formed in one face of a flowpath, so as pictured the undulations may be formed in the outer surface of the ribs of both a stationary disc and a moving disc which provides an undulating wall at each frustoconical annular shaped flowpath. Alternatively, undulations may be formed in the inner surface the ribs of both a stationary disc and a moving disc. Or alternatively, undulations may be formed in the inner and outer surfaces the ribs of only a stationary disc while the ribs of a moving disc are flat. Or alternatively, undulations may be formed in the inner and outer surfaces the ribs of only a moving disc while the ribs of a stationary disc are flat.

[0092] Referring to Fig. 5D, an alternate intermeshing rib structure 14 is shown with spiral ribs. A taper 74 may comprise an entrance and an exit of a flowpath. The taper is preferably formed on the crest of the ribs as shown in Fig. 5D because this is practical to manufacture, and also assists with mechanical loading and deflection of the rib structures in operation. These tapers 74 may help minimize a stress concentration towards the end of the rib structures, especially because the end of the ribs may be subject to higher stresses at the junction with a disc (e.g. cantilever loading) while the central portion of spiraled ribs are subject primarily to hoop stresses which are more easily withstood by the material. Furthermore, these tapers 74 may reduce the pressure drops occurring through the flowpath towards either end, which further reduces the pressure forces acting towards the end of the rib structures. Each pair of intermeshing ribs may create two spiral flowpaths, one at the crest and another at the root of each rib. It is possible and considered within this disclosure that multi-start spirals would be possible. For example, a three -start-spiral would have three ribs forming six flowpaths. The two or more primary radial flowpaths may in general be offset from each other to minimize the differential pressure between the two or more primary radial flowpaths.

[0093] Referring to Fig. 5E, an alternate intermeshing rib structure 14 is shown with labyrinthine rib structures. Similar to Fig. 5D, a single rib structure may create two labyrinthine flowpaths, one at the crest and another at the root of each rib. It is possible and considered within this disclosure that multiple labyrinthine structures would be possible within a single disc. For example, a three-start- labyrinthine would have three ribs forming six flowpaths. A labyrinthine structure may be less advantageous compared to a spiral flowpath because there are more challenging structural loads at each tip of a rib structure, and higher pressure gradients at portions of adjacent flowpaths. These less uniform pressure gradients and structures would increase leakage and make deflection of the rib structure more difficult as compared to a spiral structure, all other variables being held constant (where the most important variables are rib thickness, bending modulus, and clearance between intermeshing ribs). The flow control valve 10 may be structured to permit a degree of non-zero leakage between the two or more primary radial flowpaths, even if the primary flowpaths are otherwise hydraulically isolated.

[0094] One or both the moving part and the seating part may be structured to undulate in shape along at least a portion of a length of the primary radial flowpath.

[0095] Referring to Fig. 5F, an alternate intermeshing rib structure 14 is shown with undulations at a crest of a rib. Undulations may be replaced with gaps or slots or castellations. Undulations may provide repeated acceleration and deceleration of the flow in the flowpath to improve polymer degradation performance. Undulations may exist on both discs in a pair of intermeshing rib structures 14. If the crests of undulations are substantially aligned radially, then they may also function maintain alignment in full -open position (to ensure that the ribs will engage properly when the valve is actuated towards a closed position), and to maintain this alignment while also providing low-shear full open flowpath (the full open flowpath is substantially radial and formed by the aligned low-spots). When in a full-open position there may be minimal or no flow through the labyrinthine (or spiral) flowpath. An undulating surface of one or both the moving part and the seating part may be defined at least at a crest of intermeshing ribs that are spiral or labyrinthine, with the undulating surface defining peaks and troughs, with at least one set of troughs aligned radially, such that at an open position a radial flowpath is formed through the radially aligned troughs, while crests of the ribs remain in an overlapping position to maintain alignment between the moving part and the seating part.

[0096] Referring to Fig. 5G, an alternate intermeshing rib structure 14 is shown with undulations at a root of a rib. Undulations may provide repeated acceleration and deceleration of the flow in the flowpath to improve polymer degradation performance.

[0097] Referring to Fig. 5H, an alternate intermeshing rib structure 14 is shown with undulations in the thickness of a rib. Undulations may provide repeated acceleration and deceleration of the flow in the flowpath to improve polymer degradation performance.Referring to Fig. 6A, a wireframe view is shown of an outer surface of a moving disc, and the interface between this surface and the bore (not shown) forms an outer auxiliary flowpath 54. The moving part and the internal bore may thus collectively define the outer auxiliary flowpath. This flowpath may be cylindrical, or cylindrical with circumferential groove s / undulations as previously shown in other figures with a substantially axial flow direction. However, in Fig. 6A, the flow direction is substantially circumferential (around the perimeter) between guide rings 90. The labyrinthine flowpath may be formed by split guide rings 90 of the moving part. Guide rings 90 may be installed in a groove. Each guide ring may have a circumferential coverage of less than 360 degrees, leaving a gap 92 between its ends. This gap may provide a location for flow to pass from the space between two rings to the space between the adjacent space. Flow through the guide ring gaps is illustrated by arrows 94. Each adjacent guide ring gap 93 may be offset, for example approximately 180 degrees. It may be advantageous to use an elongated outer auxiliary flowpath with a lower aspect ratio in the flowpath cross-section, like this, in order to improve the consistency of flow restriction in the outer auxiliary flowpath, and to improve the tolerance to solids and avoid plugging or jamming in the outer auxiliary flowpath. This embodiment may also be advantageous to improve the polymer degradation performance of the fluid taking the auxiliary flowpath.Alternatively, a spiral groove (like a thread) may define the outer surface of the moving part, with the spiral groove forming the auxiliary flowpath.

[0098] Referring to Fig. 6B, along a portion of an interface between the internal bore and moving part, one or both of an outer surface of the moving part and the internal bore has a suitable shape. The interface may have an undulating surface along its axial length. The interface may have an undulating surface along its circumferential length, such as with longitudinal grooves 96. The interface may have a labyrinthine or spiral flowpath. An outer surface of a moving disc is shown similar to Fig. 6A, with a wireframe end-view. Guide rings 90 may be installed in circumferential grooves 96. The outer surface of a moving disc defining an outer auxiliary flowpath 54 may comprise longitudinal grooves 96 which have a minimum radius greater than the grooves 98 and a maximum radius less than the guide rings 90 OD. The gaps 92 and offset gaps 93 are also visible approximately 180 degrees offset. An advantage of these grooves may be to improve the shear degradation performance of polymer traversing the auxiliary flowpath.

[0099] Referring to Fig. 7, a valve 10 is shown with multiple stages, for example arranged in parallel. The flow control valve 10 may have two or more pairs of discs (discs 20 and 30) arranged in parallel or series with the moving part of each pair of discs is structured to be controlled by the valve positioner in use. Arranging stages in parallel may be advantageous for increasing flow rates, while maintaining pressure drop and polymer degradation performance (instead of increasing the rib height of a single stage). In this embodiment a sleeve 100 forms a bore for a moving disc 30. The inlet flow through outer nozzle 53 still flows past a stationary disc, but also flows around the outside of a sleeve 100. A sleeve 100 may have openings 102 where flow may enter the sleeve the access the primary flowpath 12 and outer auxiliary surface 39 of a stage. A retention fastener may not be required to hold a stationary disc 20 in position, as the stationary discs 20 may be held in position by sleeves 100. A valve positioner may include an overlapping portion 38 at the interface with each moving disc. A valve positioner is illustrated for simplicity as an integral component; however this is not practical for assembly, and couplers between multiple components throughout the valve positioner would be required. A seal 104, such as an O-ring, is formed between a stationary disc and a valve positioner. A hollow valve positioner includes openings 44 for flow. Flow direction through the openings in sleeves 100 and a valve positioner 40 are illustrated with arrows 200.

[0100] Referring to Fig. 8, a schematic of an example field installation is shown with water and mother solution (polymer at higher concentrations) being pumped separately and mixed. A common pipeline system distributes fluid to injection wells. Flow rates and injection pressures of each well may be controlled with a valve 10.

[0101] Referring to Fig. 9, a schematic of a simplified control valve 10 with a mechanical- hydraulic controller connected to the valve positioner is shown. A hydraulic cylinder 210 of a mechanical-hydraulic controller may have a cross-sectional area larger than the diameter of the actuator seals or an interface between an actuator and a moving disc. The mechanical-hydraulic controller may be used in operation to limit the maximum injection pressure of an injection control valve. A mechanical-hydraulic controller may use injection fluid as a working fluid. Tubing 202 may supply injection fluid is received from a location upstream of the control valve 204, and the hydraulic control system may discharge fluid to a location downstream of the control valve 206. The tubing 202 may include a restriction, the restriction being used to control the flow rate through the hydraulic system while creating minimal polymer degradation, such as a coiled tube with a diameter less than 0.25”. A filter 208 may be used in the tubing 202, or a strainer / screen at the upstream control valve 204 to prevent plugging in a restriction or in a regulator. A hydraulic control cylinder 210 may have a weep hole 212 such that one side of the cylinder references atmospheric pressure. Alternatively, one side of the cylinder may be connected to the fluid system a location downstream of the control valve 206, or to another reference pressure such as instrument air or another regulated pressure. Various hydraulic pilot control systems as are known in the art may be configured to achieve the desired pressure limiting operation, and one such configuration is schematically illustrated with pressure regulators. A mechanical actuator assembly 60 may be configured to act on an end rod 214 of a hydraulic controller. When configured like this, the mechanical actuator assembly 60 may be used to set the position of the valve if the injection pressure is below the setpoint (as determined by the hydraulic pilot circuit setpoint); however, when the mechanical actuator assembly 60 is retracted to an open position where the injection pressure might approach the pressure setpoint, then the hydraulic control system limits the maximum valve opening position to keep injection pressure below the setpoint, such a position is illustrated in Fig. 9.

[0102] Table of parts

[0103] 10 Flow control valve

[0104] 12 Primary Flowpath

[0105] 14 intermeshing ribs (general sense)

[0106] 16 intermeshing ribs of a primary flowpath stationary

[0107] 18 intermeshing ribs of a primary flowpath moving

[0108] 20 Stationary Disc

[0109] 21 stationary disc backing plate

[0110] 24 Stationary Disc retention fastener

[0111] 26 Stationary Disc end seal

[0112] 28 seat profile for positive closing seal

[0113] 30 Moving Disc

[0114] 31 Moving disc backing plate

[0115] 32 Backside of a moving disc

[0116] 34 inner auxiliary flowpath

[0117] 36 high-angle shoulder of the interface between the valve positioner and a moving disc

[0118] 38 axially overlapping and / or low angled portion of the interface between the valve positioner and a moving disc

[0119] 39 outer surface of a moving disc

[0120] 40 valve positioner

[0121] 42 disc puller

[0122] 44 openings of a hollow valve positioner

[0123] 50 Bore

[0124] 52 inner nozzle

[0125] 53 outer nozzle

[0126] 54 outer auxiliary flowpath

[0127] 56 end cap of the housing at the nozzle end

[0128] 57 end cap of the housing at the actuator end

[0129] 58 housing

[0130] 60 Actuator

[0131] 62 Actuator packing seal

[0132] 70 radial slots between a separate ribbed piece and backing plate of a disc

[0133] 72 predetermined location of a primary flowpath for connecting an inner auxiliary flowpath

[0134] 74 Tapered entrance / exit of a flowpath

[0135] 80 undulations at a crest of a rib

[0136] 82 undulations at a root of a rib

[0137] 84 undulations in a thickness of a rib

[0138] 90 guide ring

[0139] 92 gaps in a guide ring (located within a bore)

[0140] 93 offset gaps in an adjacent guide ring

[0141] 94 flow through guide ring gaps

[0142] 96 longitudinal grooves of an outer auxiliary flowpath

[0143] 98 circumferential grooves in a moving disc to accommodate guide rings

[0144] 100 sleeve

[0145] 102 openings in a sleeve

[0146] 104 seal

[0147] 200 mechanical -hydraulic controller

[0148] 202 Tubing

[0149] 204 location upstream of the control valve

[0150] 206 location downstream of the control valve

[0151] 208 filter

[0152] 210 hydraulic control cylinder

[0153] 212 weep hole

[0154] 214 end rod

[0155] In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A flow control valve for viscous fluids comprising: a housing with an inlet, an outlet, and an internal bore; a moving part and a seating part that have intermeshing ribs and collectively define a primary radial flowpath from the inlet to the outlet, the moving part being mounted to axially translate, relative to the seating part, within the internal bore of the housing, to adjust a resistance to flow within the primary flowpath, with the flow control valve structured to balance pressure across the moving part; and a valve positioner connected to adjust an axial position of the moving part.

2. The flow control valve of claim 1 structured such that adjustment to the axial position of the moving part, in use, adjusts a cross-sectional flow area of the primary radial flowpath.

3. The flow control valve of any one of claim 1 - 2 in which: the inlet is operatively coupled to either a radially inner end or a radially outer end of the primary radial flowpath; and the outlet is operatively coupled to the other of the radially inner end or radially outer end of the primary radial flowpath.

4. The flow control valve of any one of claim 1 - 3 in which the flow control valve is structured to balance pressure across the moving part via an auxiliary flowpath.

5. The flow control valve of claim 4 in which the auxiliary flowpath is connected to the primary radial flowpath.

6. The flow control valve of any one of claim 4 - 5 in which at least the moving part defines the auxiliary flowpath.

7. The flow control valve of claim 6 in which the moving part and the internal bore collectively define the auxiliary flowpath.

8. The flow control valve of claim 7 in which the auxiliary flowpath comprises a radially inner portion and a radially outer portion.

9. The flow control valve of claim 8 in which: the radially outer portion is defined between the moving part and the internal bore; the radially inner portion is defined between the moving part and the valve positioner; andthe moving part is connected to float relative to the valve positioner.

10. The flow control valve of any one of claim 8 in which the radially inner portion connects to the primary flowpath at a predetermined location between the radially inner and radially outer ends and is structured to have less resistance to flow relative to the radially outer portion.

11. The flow control valve of claim 9 in which: the auxiliary flowpath is defined at an interface between the valve positioner and the moving part; and one or more of: the interface between the valve positioner and the moving part is defined by a high-angle shoulder of the valve positioner that is structured not to bind in the event that the moving part comes into physical contact with the valve positioner; and the interface between the valve positioner and the moving part includes at least one low-angle tapered surface.

12. The flow control valve of claim 11 in which one or more of: the interface between the valve positioner and the moving part has an axial length greater than 0.5”; and the interface between the valve positioner and the moving part defines an angle from a central axis of the flow control valve of between 0.01 and 45 degrees.

13. The flow control valve of any one of claim 6 - 12 in which one or more of: the valve positioner and moving part define an undulating surface along the axial length of an interface between the valve positioner and the moving part; the inlet or the outlet is defined through a central hole of the seating part; the inlet and the outlet are defined within an end cap of the housing; the primary radial flowpath is structured to have a length that is greater than a radius of the moving part; and the primary radial flowpath is structured to be one or more of spiral, labyrinthine, or radial at an angle less than 90 degrees from an axis of the flow control valve.

14. The flow control valve of any one of claim 1 - 13 in which one or more of: the seating part is dimensioned to have an outer radius that is smaller than an inner radius of the internal bore of the housing by at least a radial clearance of 0.050” for at least half of a circumferential distance along a perimeter of the seating part; and an outer diameter of the moving part is smaller than the internal bore of the housing by a radial clearance of between 0.001” and 0.020”.

15. The flow control valve of claim 14 in which, along a portion of an interface between the internal bore and moving part, one or both of an outer surface of the moving part and the internal bore has one or more of: an undulating surface along its axial length; an undulating surface along its circumferential length; or a labyrinthine or spiral flowpath.

16. The flow control valve of claim 15 in which the labyrinthine or spiral flowpath is formed by split guide rings of the moving part.

17. The flow control valve of any on of claim 1 - 16 in which one or both the moving part and the seating part are structured to undulate in shape along at least a portion of a length of the primary radial flowpath.

18. The flow control valve of claim 17 in which an undulating surface of one or both the moving part and the seating part is defined at least at a crest of intermeshing ribs that are spiral or labyrinthine, with the undulating surface defining peaks and troughs, with at least one set of troughs aligned radially, such that at an open position a radial flowpath is formed through the radially aligned troughs, while crests of the ribs remain in an overlapping position to maintain alignment between the moving part and the seating part.

19. The flow control valve of any one of claim 1 - 18 in which one or more of: a length of the primary radial flowpath is between 12” and 3000”; a thickness of each intermeshing rib is between 0.030” and 1.000”; and an inner diameter of the internal bore is between 3” and 20”.

20. The flow control valve of any one of claim 1 - 19 in which the moving part and the seating part comprise a pair of discs.

21. The flow control valve of claim 20 in which the flow control valve has two or more pairs of discs arranged in parallel or series with the moving part of each pair of discs is structured to be controlled by the valve positioner in use.

22. The flow control valve of any one of claim 1 - 21 further comprising one or more of: a mechanical-hydraulic controller connected to operate the valve positioner; and a filter, strainer, or screen upstream of the primary radial flowpath or in pilot hydraulic fluid piping to the fluid control valve to prevent plugging in a restriction or a regulator.

23. The How control valve of any one of claim 1 - 22 in which: the intcrnicshing ribs form two or more primary radial flowpaths in parallel; and the valve positioner is connected to adjust the resistance to flow within the two or more primary radial flowpatlis.

24. The flow control valve of claim 23 in which one or more of: the flow control valve is structured to permit a degree of non-zero leakage between the two or more primary radial flowpaths; and the two or more primary' radial flowpaths are offset from each other to minimize the differential pressure between the two or more primary radial flowpatlis.

25. A method comprising using the flow control valve of any one of claim I - 24 to limit a maximum pressure downstream of the flow control valve via a hydraulic control system which is supplied by the same viscous injection fluid as the flow control valve.

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