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i J 11 WE CLAIM:
1. An assembly for well flow control with multi-stage restriction,
comprising:
a tubular base pipe comprising a sidewall aperture that communicates
5 fluid between an interior central bore of the base pipe and an exterior of
the base pipe;
a filtration screen around the base pipe, the filtration screen
defining a lateral fluid passage along a axial length of the well screen
assembly; and
10 a flow control device coupled to the base pipe and the filtration screen,
comprising a ring sealing the lateral fluid passage from the central bore
and an elongate restrictor passage in the ring, oriented longitudinally and
configured to communicate fluid between the lateral fluid passage and the
central bore, the restrictor passage comprising a plurality of internal,
15 square edged orifices each defined by a fixed, annular protrusion
extending inwardly from an interior surface of the restrictor passage.
2. An assembly as claimed in claim 1, where each orifice is square edged on
both a first opening and an opposing opening.
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3. An assembly as claimed in claim 1, where the annular protrusion
comprises a square shoulder that is orthogonal to the longitudinal axis of
the restrictor passage.
4. An assembly as claimed in claim 2, where the annular protrusion
comprises a second square shoulder opposite the first mentioned shoulder,
the second shoulder is orthogonal to the longitudinal axis of the restrictor
passage.
5. An assembly as claimed in claim 3, where the annular protrusion
comprises an inner sidewall surface extending from the first mentioned
10
shoulder to the second shoulder, and the iimer sidewall surface is parallel
to the longitudinal axis of the restrictor passage.
6. An assembly as claimed in claim 4, where the inner sidewall surface of
the restrictor passage meets the first mentioned shoulder at a right angle,
without a fillet or chamfer.
7. An assembly as claimed in claim 3, where the annular protrusion
10 comprises a cylindrical inner sidewall svirface extending from the first
mentioned shoulder to the second shoulder.
8. An assembly as claimed in claim 1, where the flow area through the
orifices is the most restrictive flow area through the flow control device.
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9. An assembly as claimed in claim 1, where the orifices are equally spaced
along the longitudinal length of the restrictor passage.
20 10. An assembly as claimed in claim 1, where the flow area of one orifice is
different than the flow area of anther orifice.
11. An assembly as claimed in claim 1, where the length of annular protrusion
25 along the longitudinal axis of the restrictor passage is less than half the
largest transverse inner dimension of the restrictor passage.
12. An assembly as claimed in claim 1, where the length of annular protrusion
along the longitudinal axis of the restrictor passage is less than the largest
30 transverse iimer dimension of the annular protrusion.
13. An assembly as claimed in claim 1, where the restrictor passage is an
internal bore of a tube that is threadingly secured in the ring.
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14. An assembly as claimed in claim 1, where the flow control device
comprises a second elongate restrictor passage in the ring, and the second
restrictor passage communicates fluid between the lateral fluid passage
and the central bore, and the second restrictor passage is azimuthally
spaced from the first mentioned restrictor passage.
15. An assembly as claimed in claim 1, where the restrictor passage extends
10 from a location proximate the lateral fluid passage of the screen and a
location proximate the sidewall aperture of the base pipe.
16. An assembly as claimed in claim 1, where the restrictor passage apart
from the annular protrusions has a substantially uniform transverse
15 dimension.
17. A well device, comprising:
a tubing having a sidewall aperture through to the central bore of
the tubing;
20 a flow control housing carried on the tubing and defining an
annular chamber over the aperture;
a flow control ring sealing a first portion of the annular chamber in
fluid communication with the aperture from a second portion of the
annular chamber; and
25 an orifice tube extending longitudinally through the flow control
ring and communicating the first and second portions of the annular
chamber, the orifice tube comprising a pluraUty of internal, square edged
orifices each defined by a fixed, annular protrusion extending inwardly
from an interior surface of the orifice tube.
18. A well device as claimed in claim 16, where the orifice tube apart from
the annular protrusions has a substantially uniform transverse dimension.
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19. A well device as claimed in claim 18, where the length of annular
protrusion along the longitudinal axis of the orifice tube is less than half
the largest transverse inner dimension of the orifice tube.
5 20. A method of controlling flow in a well, the method comprising:
receiving, in a flow control device, flow between an interior central
bore of a tubular base pipe and a filtration screen about the base pipe; and
restricting the flow with an elongate restrictor passage oriented
longitudinally and comprising a plurality of internal, square edged orifice
10 defined by a fixed, annular protrusion extending inwardly from an interior
surface of the restrictor passage.
21. A method as claimed in claim 20, further comprising affixing a flow tube
15 comprising the restrictor passage into the flow control device.