This invention relates generally to control valves, and more particularly to chokes which serve to dissipate the energy of high pressure fluid, as for example fluid rising in a well.

Choke valves are commonly connected to the well annulus at the well surface to dissipate the energy of hig pressure fluid, the latter commonly entraining small particles including drill cuttings loosened from the under¬ ground well formation. Such material can and does des¬ tructively erode the non-metallic seal carried by the choke valve due to exposure of the seal to the fluid flow when the valve is partly open, i.e. in fluid energy dissipating position. In this regard, when the valve is closed the seal is. not exposed to abrasive fluid flow as the latter is stopped. There is need for a valve construction characterized by substantially reduced seal erosion and correspondingly increased life. Also, there is need for a choke valve construction further characterized by unusual simplicity and overall improved design, for com¬ patibility with suddenly high well fluid pressure, as during a 'kick' in the mud flow upwardly in the annulus between the well casing and drill pipe.

The major aim of the invention is to provide an improved choke valve meeting the above needs. Basically, the multiposition choke valve assembly of the invention includes, in combination: a) a valve body defining an interior chamber and inlet and outlet flow ports communicable with that chamber, and b) a valve stopper sub-assembly movable axially longitudinally in the chamber, the sub-assembly including an axially extending stem, an axially extending sleeve, an annular section located between the stem and sleeve, and an annular seal on said annular section and exposed at the section periphery, c) the sleeve forming multiple through openings

and having a retracted position in which the flow passes with relatively lesser velocity past the seal and then for- wardly to pass via said openings with relatively increased velocity into the sleeve, followed by generally axially forward flow toward the outlet flow port, d) the sleeve having an advanced position in which the seal is radially compressed to engage a body bore, and said flow through, said sleeve openings- is blocked.

Further features and advantages of the invention, as well as the details of preferred embodiment, will be more fully understood from the following specification and drawings, in which:

Fig. 1 is an elevation showing a choke valve con¬ nected with a well installation;

Fig. 2 is an enlarged horizontal view, partly in section, taking on lines 2-2 of Fig. 1;

Fig. 3 is a section in plane view on lines 3-3 of Fig. 2; showing the choke valve fully open;

Fig. 4 is a view like Fig. 3, showing the choke valve fully closed;

Fig. 5 is a further enlarged view showing details of valve elements during full closure;

Fig. 5a is a yet further enlarged fragmentary section showing details of valve elements during full closure;

Fig. 5b is a view like Fig. 5a showing details of valve elements, as related to flow during partial closure of the valve; and

Fig. 5£ is a view like Fig. 5b , the valve being fully open.

Referring first to Fig. 1, a choke valve 10 is shown as sidewardly connected at 11 to a well casing 12, to receive pressurized fluid, as for example highly pres¬ surized drilling mud typically containing sand or other particulate. The casing typically contains drill pipe 13 via which mud is circulated downwardly, as indicated by

arrow 14.

Extending the description to Figs..2 and 3, the illustrated choke valve 10 is shown to include a valve body 15, a body cap 15a, and interfitting annular members 15b, 15£, 15d and 15 . The latter are received in body bores 16a-16£, as shown. Body stop shoulders 17a_ and 17b seat flange surfaces 18 and 19 on members 15 and 15<e, ^• respectively, and cap 15a retains the members 15b_ 15e_ in position.

A chamber 20 is formed interiorly of the body 15 to extend annularly about an intermediate portion of member 15 . The latter has a number of ports 21 through its wall, so that fluid received via body side inlet port 22 into annular chamber 20 is passed via ports 21 into the interior space 23 within member 15£. The latter is communicable with outlet port 24 to discharge fluid, as via line 25, to a sump or other area.

A valve stopper sub-assembly is provided as at

26 to be movable longitudinally in the direction of axis

27 in chamber 20 and space 23. That sub-assembly includes an axially extending stem 28, an axially extending sleeve 29, and annular section, as for example flange 30, located between stem 28 and sleeve 29. An actuator to move the stem and sleeve axially may for example include a piston 31 attached at 31a to the reduced diameter stem extension 28a, the piston movable in one direction within cylinder 32 in response to control fluid pressure applied via line 33 to chamber 34 in the cylinder; and the piston is movable in the opposite direction within cylinder 32 in response to control fluid pressure application via line 35 to chamber 36 in the cylinder. One end of the cylinder 32 is retained to cap 15a as by a head 39 closing the opposite end of the cylinder, and fasteners 40 connected to. the head and cap. See also seal 85' between cap 15a_ and ^' stem extension 28a, and seal 86' between head 39 and stem further extension 28a

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Extending the description to Figs. 5a _^ to 5£, the metallic flange 30 carries an annular seal 42, which may fo example consist of elastomeric material. Flange 30 and sleeve 29 may typically consist of wear resistant material, i.e. tungsten carbide; and member 15d may also consist of such material. The seal is located at a side 30a of the flange remote from the sleeve 29, the latter for example being integral with the flange. The seal may have dove tail or undercut interfit with side 30a of the flange, to aid its retention to the flange.

The sleeve forms multiple through openings 43 spaced about axis 27, for directing divided fluid flow streams into the sleeve interior to impinge upon one another and dissipate (i.e. choke) flow energy, in re¬ tracted positions of the sleeve and sub-assembly 26 (see Figs. 3 and 5b_) . In this regard, as the sub-assembly is advanced the openings 43 are progressively closed by the bore well 44, to reduce the flow discharge at 25. In fully advanced position of the sleeve, (see Figs. 4 and 5a) the side openings 43 are closed off by bore wall 44; and the seal is squeezed or compressed radially to forcibly seal against wall (counterbore) 44, fully closing off the flow through the valve. To this end, an actuator is provided to extend against the tapered side 42a_ of the seal. The illustrated actuator 47 is cylindrical and has a tapered forward surface interfitting the seal wall 42a_. A re¬ tainer such as fastener 50 retains the actuator to the an¬ nular section or flange 30 for axial movement therewith between sleeve advanced and retracted positions. The re¬ tainer is thread connected at 51 to the actuator body 52, for adjusting the axial compression of the seal, to achieve desired fit with bore wall 44.

It is an important feature of the invention that, due to the mounting of the seal on flange 30 so as to be substantially larger in outer diameter than the sleeve 29, the fluid flow is caused to pass with relatively lesser velocity past the seal (see arrow 56 in Fig. 5c) , and

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then forwardly with relatively increased velocity (see arro 57 in Fig. 5£) past the tapered end walls 58 and 59 of the flange, to pass at 6Q through the openings.43 into the sleeve interior space 61, where the flow streams impinge upon one another. The flow then passes generally axially toward the discharge at 25. As a result, abrasive particle in the flow pass with lesser velocity near to or against th seal, so that lesser seal wear results, and seal life is enhanced. Also, with the valve sub-assembly set in flow reduced position as seen in Fig. 5b, with the flange 30 close to end face 64 of member 15d, the seal remains suf¬ ficiently spaced from that end face, so that abrasive par¬ ticles too large to pass through the gap 67 between 58 and 80 (see Fig. 5b) are trapped out of contact with the seal, whereby seal wear is reduced or prevented. Gap 67 is., smaller in width than the widths of other gaps or openings down stream of gap 67 to ensure that any particle passing through gap 67 will not be further trapped. If flushing of such larger particles is desired the sub-assembly may be moved upwardly, slightly. Note counterbore 44 in Fig 5, receiving the flange 30. However, gap 67 is larger in area than the flow passing areas of the downstream through open¬ ings. In full open position as shown in Fig. 5£, the valve can pass large cuttings with no entrapment areas. As the sleeve and flange move forwardly, the seal annular outer surface 42b engages annular forward taper 80 on the member 15d, which progressively squeezed the seal to compress it radially, as is clear from Figs. 5a and 5£. After flange taper 59 abuts to stops against member face 64a_, stem 28 may be advanced further to close gap 82 in Fig. 5a (and open a corresponding gap at 83) to further pressurize the seal 42 and increase sal pressure on bore 44.

In addition, member 15d floats slightly, in position due to clearances at 84, 85 and 86 in Fig. 3, so as to adjust radially on assembly to interfit with sleeve 29 as th latter advances. See also face seal 87 between floating

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member 15d_ and nonfloating member 15e.- The following characteristics are of importance: a) _. In valve full open position, large cutting can pass, bl In mid-stroke position the valve acts like a gate or seat valve; or by adding a pair of holes as at 43, it acts like a jet choke, c) In fully closed position, the seal is energized on a large flange diameter for lower flow velocities. d) -The stem end of sleeve 29 is sacrificial and may erode away by abrasion without preventing valve functioning.

Figs. 3 and 4 also show the provision of a valve position sensing and measuring device indicated generally at 41. It includes an element 70 attached at 71 to stem extension 28a_' , and movable into and out of axial position sensor 72. A pressure line 73 communicates sensing fluid pressure (.indicative of valve position) to an external meter or other recorder.

Finally, the sleeve 29 may be free of openings 29, and in that case it does provide a sacrificial erodable element, as referred to above.