A choke controlling fluid flow in a well has a conduit with an inlet and an outlet, and a flow restrictor comprising first and second choke members ( 10,20 ), one of which ( 20 ) rotates relative to the other ( 10 ) to choke or promote flow. The first and second choke members ( 10,20 ) are axially spaced from one another, and have mating faces that are optionally planar, and are axially stacked in the choke. The choke is operated by a shifting tool ( 50 ), which grips the inner surface of the rotating choke member ( 20 ), and rotates it relative to the other ( 10 ), in order to vary the flow.
1. A choke adapted for downhole use in a subterranean well, the choke comprising:
a conduit with a bore;
a first opening allowing fluid communication between an outside of the conduit and the choke;
a second opening allowing fluid communication between the choke and the bore of the conduit;
a flow path connecting the first and second openings;
a flow restrictor that is selectively adjustable to change a cross sectional area of the flow path through the choke, the flow restrictor comprising first and second cylindrical choke members, each of the first and second choke members incorporating a portion of the flow path;
wherein a first end of the first choke member abuts a second end of the second choke member;
wherein the first choke member is rotatable relative to the second choke member; and
wherein the first choke member is configured to be rotated by a shifting tool which is lowered into the bore of the conduit from a surface of the earth after the choke has been installed in the subterranean well.
2. The choke according to claim 1 , wherein the first and second ends are planar.
3. The choke according to claim 1 , wherein the choke incorporates a resilient device arranged to urge the first and second ends together.
4. The choke according to claim 3 , wherein the resilient device urges the first and second ends together during flow of fluid through the first and second choke members.
5. The choke according to claim 1 , wherein the choke includes a detent adapted to control a relative rotational position of the first and second choke members.
6. The choke according to claim 5 , wherein the detent comprises an indexing device which permits relative rotation of the first choke member relative to the second choke member in predetermined increments.
7. The choke according to claim 1 , wherein the choke incorporates a piston device exposed to fluid pressure.
8. The choke according to claim 7 , wherein the piston device forms a part of the first choke member.
9. The choke according to claim 7 , wherein the piston device incorporates a first seal and a second seal exposed to fluid pressure from outside of the choke, the first and second seals having different diameters.
10. The choke according to claim 7 , wherein a force urging the first and second choke members together is controlled at least partially by fluid pressure acting on the piston device during flow of fluid through the first and second choke members.
11. The choke according to claim 10 , wherein the first and second choke members are pressed together in an axial direction by a fluid pressure differential across the first and second choke members.
12. The choke according to claim 3 , wherein the choke includes a piston device and wherein a force pressing the first and second choke members together is controlled by at least one of the piston device and the resilient device.
13. The choke according to claim 3 , wherein the choke includes a piston device having a piston area, and wherein the piston area is selected such that sticking of the choke is prevented.
14. The choke according to claim 3 , wherein the resilient device controls a force urging the first and second choke members together.
15. The choke according to claim 1 , wherein at least one aperture in at least one of the first and second choke members is arcuate.
16. The choke according to claim 15 , wherein each of the first and second choke members has an arcuate aperture, and wherein the apertures are arranged to at least partially intersect when the choke is in an open configuration.
17. The choke according to claim 15 , wherein the at least one aperture comprises one or more supporting webs extending from one side of the aperture to the other.
18. The choke according to claim 15 , wherein the at least one aperture extends for less than 180°.
19. The choke according to claim 15 , wherein a series of apertures arranged on an arc is provided in the second choke member and a single arcuate aperture is provided in the first choke member.
20. The choke according to claim 15 , wherein a cross-sectional area of the at least one aperture increases in one rotational direction.
21. The choke according to claim 1 , wherein at least one of the first and second choke members comprises at least one erosion-resistant material.
22. The choke according to claim 1 , wherein the flow path has an axial portion that is parallel to an axis of the choke.
23. The choke according to claim 22 , wherein the flow restrictor is in the axial portion.
24. The choke according to claim 1 , wherein the first and second choke members form an axial stack.
25. The choke according to claim 1 , wherein at least one of the first and second ends is coated or faced with an erosion-resistant material.
26. The choke according to claim 1 , wherein at least one of the first and second ends is coated or faced with a friction reducing material.
27. The choke according to claim 1 , including an annular chamber formed by recesses between radially spaced surfaces of the first and second choke members, wherein the chamber is disposed in the flow path between the first opening and the second opening.