U.S. patent application number 11/410996 was filed with the patent office on 2007-10-25 for well screens having distributed flow.
Invention is credited to William M. Richards.
Application Number | 20070246212 11/410996 |
Document ID | / |
Family ID | 38135380 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070246212 |
Kind Code |
A1 |
Richards; William M. |
October 25, 2007 |
Well screens having distributed flow
Abstract
Well screens having distributed flow. A well screen includes a
generally tubular structure having a longitudinal axis, and a
passage for flow between an interior and an exterior of the well
screen; and a filter assembly having a restriction to flow which
varies in a direction parallel to the longitudinal axis. A well
system includes a well screen including a passage for flow between
an interior and an exterior of the well screen, and a filter
assembly having a series of longitudinally extending sections, the
series of filter assembly sections having a restriction to flow
which increases in a direction toward the passage.
Inventors: |
Richards; William M.;
(Frisco, TX) |
Correspondence
Address: |
SMITH IP SERVICES, P.C.
P.O. Box 997
Rockwall
TX
75087
US
|
Family ID: |
38135380 |
Appl. No.: |
11/410996 |
Filed: |
April 25, 2006 |
Current U.S.
Class: |
166/227 ;
166/236 |
Current CPC
Class: |
E21B 43/121
20130101 |
Class at
Publication: |
166/227 ;
166/236 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A well screen, comprising: a longitudinal axis; and a filter
assembly having a restriction to flow which varies in a direction
parallel to the longitudinal axis.
2. The well screen of claim 1, further comprising a passage for
flow between an interior and an exterior of the well screen, and
wherein the restriction to flow increases in the direction toward
the passage.
3. The well screen of claim 1, wherein the restriction to flow
varies in discrete increments.
4. The well screen of claim 1, wherein the restriction to flow
varies continuously.
5. The well screen of claim 1, wherein the varied restriction to
flow results from a variation in a filter material of the filter
assembly, and where the variation is in at least one of density,
permeability, porosity, bonding resin, matrix, thickness, particle
size, consolidation, and material type of the filter material.
6. The well screen of claim 1, wherein the varied restriction to
flow is a result of a varied number of layers of filter material in
the filter assembly.
7. The well screen of claim 1, wherein the varied restriction to
flow is a result of a varied number of openings in the filter
assembly.
8. The well screen of claim 1, wherein the varied restriction to
flow is a result of a varied size of openings in the filter
assembly.
9. The well screen of claim 1, wherein the varied restriction to
flow is a result of a varied spacing between successive elements of
the filter assembly.
10. The well screen of claim 1, wherein the passage extends through
a device which restricts flow of a fluid which flows through the
filter assembly.
11. A well system, comprising: a well screen including a passage
for flow between an interior and an exterior of the well screen,
and a filter assembly having a series of longitudinally extending
sections, the series of filter assembly sections having a
restriction to flow which increases in a direction toward the
passage.
12. The well system of claim 11, wherein a first one of the
sections overlies the passage, and a second one of the sections is
farther from the passage than the first section, the restriction to
flow through the first section being greater than the restriction
to flow through the second section.
13. The well system of claim 11, wherein the restriction to flow
varies in discrete increments.
14. The well system of claim 11, wherein the restriction to flow
varies continuously in the series of sections.
15. The well system of claim 11, wherein the increased restriction
to flow results from a variation in a filter material of the filter
assembly, and where the variation is in at least one of density,
permeability, porosity, bonding resin, matrix, thickness, particle
size, consolidation, and material type of the filter material.
16. The well system of claim 11, wherein the increased restriction
to flow is a result of an increased number of layers of filter
material in the filter assembly.
17. The well system of claim 11, wherein the increased restriction
to flow is a result of a decreased number of openings in the filter
assembly.
18. The well system of claim 11, wherein the increased restriction
to flow is a result of a decreased size of openings in the filter
assembly.
19. The well system of claim 11, wherein the increased restriction
to flow is a result of a decreased spacing between successive
elements of the filter assembly.
20. The well system of claim 11, wherein the passage extends
through a device which restricts flow of a fluid which flows
through the filter assembly.
21. A well screen, comprising: a tubular structure made up of
multiple longitudinal tubular structure sections; and a filter
assembly made up of multiple longitudinal filter assembly
sections.
22. The well screen of claim 21, further comprising a passage for
flow between an interior and an exterior of the well screen, and
wherein the filter assembly sections have a restriction to flow
which increases in a direction toward the passage.
23. The well screen of claim 21, wherein the tubular structure has
a longitudinal axis, and wherein the filter assembly has a
restriction to flow which varies in a direction parallel to the
longitudinal axis.
24. The well screen of claim 21, wherein the tubular structure
sections are joined to each other with flush threaded joints.
25. The well screen of claim 21, wherein the filter assembly
sections are joined to each other with flush threaded joints.
Description
BACKGROUND
[0001] The present invention relates generally to equipment
utilized and operations performed in conjunction with a
subterranean well and, in an embodiment described herein, more
particularly provides well screens having distributed flow.
[0002] Conventional well screens have a filter or screen material
which overlies one or more openings in a base pipe. The screen
material has a constant restriction to flow therethrough along its
length. Due to the presence of the openings, however, the pressure
drop across the screen material is greatest near the openings, and
decreases away from the openings.
[0003] As a result, higher flow rates and increased erosion are
experienced in the screen material near the openings where the
pressure drop is greatest. The remainder of the screen material is
not effectively utilized.
[0004] Therefore, it may be seen that improvements are needed in
the art of constructing well screens. It is among the objects of
the present invention to provide such improvements.
SUMMARY
[0005] In carrying out the principles of the present invention, a
well screen is provided which solves at least one problem in the
art. One example is described below in which flow through the well
screen is distributed in a manner reducing localized erosion.
Another example is described below in which a filter assembly of
the well screen has a restriction to flow which varies in order to
more evenly longitudinally distribute flow through the filter
assembly.
[0006] In one aspect of the invention, a well screen is provided
which includes a longitudinal axis. A filter assembly of the well
screen has a restriction to flow which increases in a direction
parallel to the longitudinal axis. The restriction to flow may
increase in a direction toward a passage for flow between an
interior and an exterior of the well screen.
[0007] In another aspect of the invention, a well system includes a
well screen with a passage for flow between an interior and an
exterior of the well screen. A filter assembly of the well screen
has a series of longitudinally extending sections. The series of
filter assembly sections have a restriction to flow which increases
in a direction toward the passage.
[0008] In yet another aspect of the invention, a well screen is
provided which includes a tubular structure made up of multiple
longitudinal tubular structure sections and a filter assembly made
up of multiple longitudinal filter assembly sections. This
construction of the well screen enables very long well screens to
be assembled during installation in a well.
[0009] These and other features, advantages, benefits and objects
of the present invention will become apparent to one of ordinary
skill in the art upon careful consideration of the detailed
description of representative embodiments of the invention
hereinbelow and the accompanying drawings, in which similar
elements are indicated in the various figures using the same
reference numbers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic partially cross-sectional view of a
well system embodying principles of the present invention;
[0011] FIG. 2 is an enlarged scale schematic quarter-sectional view
of a well screen which may be used in the well system of FIG.
1;
[0012] FIG. 3 is a schematic quarter-sectional view of a first
alternate construction of the well screen;
[0013] FIG. 4 is a schematic quarter-sectional view of a second
alternate construction of the well screen;
[0014] FIG. 5 is a schematic quarter-sectional view of a third
alternate construction of the well screen;
[0015] FIG. 6 is a schematic quarter-sectional view of a fourth
alternate construction of the well screen;
[0016] FIG. 7 is a schematic quarter-sectional view of a fifth
alternate construction of the well screen;
[0017] FIG. 8 is a schematic quarter-sectional view of a sixth
alternate construction of the well screen; and
[0018] FIG. 9 is a schematic quarter-sectional view of a seventh
alternate construction of the well screen.
DETAILED DESCRIPTION
[0019] It is to be understood that the various embodiments of the
present invention described herein may be utilized in various
orientations, such as inclined, inverted, horizontal, vertical,
etc., and in various configurations, without departing from the
principles of the present invention. The embodiments are described
merely as examples of useful applications of the principles of the
invention, which is not limited to any specific details of these
embodiments.
[0020] In the following description of the representative
embodiments of the invention, directional terms, such as "above",
"below", "upper", "lower", etc., are used for convenience in
referring to the accompanying drawings. In general, "above",
"upper", "upward" and similar terms refer to a direction toward the
earth's surface along a wellbore, and "below", "lower", "downward"
and similar terms refer to a direction away from the earth's
surface along the wellbore.
[0021] Representatively illustrated in FIG. 1 is a well system 10
which embodies principles of the present invention. A production
tubing string 12 is installed in a wellbore 14 of a well. The
tubing string 12 includes multiple well screens 16 positioned in an
uncased generally horizontal portion of the wellbore 14.
[0022] One or more of the well screens 16 may be positioned in an
isolated portion of the wellbore 14, for example, between packers
18 set in the wellbore. In addition, or alternatively, many of the
well screens 16 could be positioned in a long, continuous portion
of the wellbore 14, without packers isolating the wellbore between
the screens.
[0023] Gravel packs could be provided about any or all of the well
screens 16, if desired. A variety of additional well equipment
(such as valves, sensors, pumps, control and actuation devices,
etc.) could also be provided in the well system 10.
[0024] It should be clearly understood that the well system 10 is
merely representative of one well system in which the principles of
the invention may be beneficially utilized. However, the invention
is not limited in any manner to the details of the well system 10
described herein. For example, the screens 16 could instead be
positioned in a cased and perforated portion of a wellbore, the
screens could be positioned in a generally vertical portion of a
wellbore, the screens could be used in an injection well, rather
than in a production well, etc.
[0025] Referring additionally now to FIG. 2, an enlarged scale
schematic quarter-sectional view of the screen 16 is
representatively illustrated. The well screen 16 may be used in the
well system 10, or it may be used in any other well system in
keeping with the principles of the invention.
[0026] As depicted in FIG. 2, the well screen 16 includes a
generally tubular structure 20 and a filter assembly 22. The
tubular structure 20 includes a member known to those skilled in
the art as a base pipe 24. In the example shown in FIG. 2, the base
pipe 24 is provided with threaded ends for interconnection in the
tubing string 12. When interconnected in the tubing string 12, a
longitudinal axis 28 of the tubular structure will form a part of
the longitudinal axis of the tubing string.
[0027] A passage 26 is formed in the base pipe 24 in order to
permit flow between the exterior and interior of the well screen
16. The passage 26 is depicted in FIG. 2 as being positioned
approximately in the middle along the length of the base pipe 24,
but other positions may be used, if desired. Furthermore, although
only one passage 26 is illustrated, multiple passages may be used
in keeping with the principles of the invention.
[0028] The passage 26 may be formed directly through the base pipe
24 as depicted in FIG. 2, or it may be formed in an orifice or
nozzle, in a check valve, in an inflow control device, in a locally
or remotely operated valve or choke for selectively varying a rate
of flow through the well screen 16, etc. Any type or configuration
of the passage 26 may be used in keeping with the principles of the
invention.
[0029] In one of the important beneficial features of the well
screen 16, the filter assembly 22 is configured so that localized
erosion of the filter assembly proximate the passage 26 is reduced
or eliminated. Specifically, the filter assembly 22 includes a
series of longitudinally extending sections 30, 32, 34, 36, 38
having varying restrictions to flow therethrough, and which
function to alter the distribution of flow through the filter
assembly.
[0030] The section 34 which directly overlies the passage 26 is
more restrictive to flow than the sections 32, 36 which are on
either side of the section 34. Similarly, the sections 32, 36 are
each more restrictive to flow than the sections 30, 38 on either
side of the sections 32, 36. In this manner, the restriction to
flow through the filter assembly 22 increases in a direction toward
the passage 26 and parallel to the longitudinal axis 28 of the
tubular structure 20.
[0031] The flow through the section 34 is indicated in FIG. 2 by a
single arrow 40, the flow through the sections 32, 36 is indicated
by multiple arrows 42, and the flow through the sections 30, 38 is
indicated by a further increased number of arrows 44. The increased
number of arrows is intended to represent a reduced restriction to
flow, and not necessarily an increased flow rate through any
section relative to another section.
[0032] For example, the restriction to flow through the sections
30, 32, 34, 36, 38 may be designed so that the rates of the flows
40, 42, 44 are approximately equal. In this manner, the flow
through the filter assembly 22 may be evenly distributed along the
filter assembly. This option may be desired in order to evenly
distribute erosion along the filter assembly 22.
[0033] An alternative would be to design the flow restrictions
through the sections 30, 32, 34, 36, 38 so that the flows 44 have
an increased rate relative to the flows 42, and so that the flows
42 have an increased rate relative to the flow 40. Yet another
alternative would be to design the flow restrictions so that the
flow 40 has an increased rate relative to the flows 42, and so that
the flows 42 have an increased rate relative to the flows 44. Still
another alternative would be to design the flow restrictions so
that the flows 42 have an increased or decreased rate relative to
each of the flows 44, 40. It will be appreciated that a wide
variety of variations in flow rate may be accomplished using the
principles of the invention, which is not limited to only the
examples described above.
[0034] Each of the sections 30, 32, 34, 36, 38 is preferably made
using a construction known to those skilled in the art as a
"pre-pack," in which granular material (such as sand, gravel,
synthetic material, etc.) is formed in a layer (for example, using
a resin to consolidate the granular material) which acts to filter
fluid flowing therethrough. The resistance to flow through the
sections 30, 32, 34, 36, 38 may be varied by changing the granular
material type, changing the porosity and/or permeability of the
pre-pack layer, changing the size of particles of the granular
material, changing the bonding resin or matrix, changing the
density of the granular material, changing the manner in which the
granular material is consolidated, changing the thickness of the
sections, etc.
[0035] Of course, it is not necessary for the sections 30, 32, 34,
36, 38 to be made using the pre-pack construction. The sections 30,
32, 34, 36, 38 could instead be made using constructions known to
those skilled in the art as "sintered," "wire-wrapped," "mesh,"
"woven," or any other type of construction or combination of
constructions. The sections 30, 32, 34, 36, 38 may be joined to
each other and to other components of the filter assembly 22 and
tubular structure 20 using any method, such as welding, threading,
bonding, fastening, etc.
[0036] Referring additionally now to FIG. 3, an alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, the passage 26
is positioned closer to one end of the tubular structure 20 (the
left end as viewed in FIG. 3), instead of being positioned in the
middle as depicted in FIG. 2.
[0037] Accordingly, the section 34 having the most restriction to
flow is positioned overlying the passage 26 on the left side of the
filter assembly 22, the sections 32, 36 having reduced restriction
to flow are positioned to the right of the section 34, and the
sections 30, 38 having the least restriction to flow are positioned
on the right side of the filter assembly. It will be appreciated
that this configuration will result in a more even distribution of
flow through the filter assembly 22, as compared to conventional
well screen construction, since the restriction to flow still
increases in a direction toward the passage 26. Thus, it will also
be appreciated that the passage 26 may be positioned anywhere in
the tubular structure 20 in keeping with the principles of the
invention.
[0038] Referring additionally now to FIG. 4, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, the filter
assembly 22 has the sections 30, 32, 34, 36, 38 arranged
longitudinally along the tubular structure 20 as in FIG. 2,
however, the sections are made up of layers of mesh screen
material.
[0039] Specifically, the section 34 which overlies the passage 26
includes three layers of mesh screen material, each of the sections
32, 36 includes two layers of mesh screen material, and each of the
sections 30, 38 includes only one layer of mesh screen material. In
this manner, the section 34 has an increased restriction to flow
relative to the sections 32, 36, and the sections 32, 36 have an
increased restriction to flow relative to the sections 30, 38.
[0040] Other ways of varying restriction to flow using mesh
material include changing the mesh size, changing the mesh
material, changing the material dimensions, changing the weave
pattern, etc. Any way of varying the restriction to flow in the
sections 30, 32, 34, 36, 38 may be used in keeping with the
principles of the invention.
[0041] Note that the layers of filter material in the sections 30,
32, 34, 36, 38 are not necessarily made of screen mesh. For
example, the layers could instead be made of pre-pack,
wire-wrapped, sintered, or any other type of filter material, and
any combination of filter materials.
[0042] The use of the layers of filter material results in the
section 34 being thicker than the sections 32, 36, and the sections
32, 36 being thicker than the sections 30, 38. Differing
thicknesses of filter material may be used to vary restriction to
flow through the sections 30, 32, 34, 36, 38 without the use of
multiple layers of filter material. For example, pre-pack, sintered
and other types of filter material may be made in different
thicknesses to thereby vary restriction to flow through the filter
material.
[0043] The filter assembly 22 as depicted in FIG. 4 also includes a
protective outer shroud 46 overlying the sections 30, 32, 34, 36,
38. The shroud 46 has openings 48 formed therethrough for admitting
flow from the exterior of the well screen 16.
[0044] Fewer openings 48 are provided for the section 34 as
compared to the sections 32, 36, and fewer openings are provided
for the sections 32, 36 as compared to the sections 30, 38. It will
be appreciated that a reduced number of the openings 48 will result
in an increased restriction to flow through the sections 30, 32,
34, 36, 38. Alternatively, or in addition, the openings 48 could
have a reduced size to increase a restriction to flow therethrough.
The openings 48 may be progressively fewer and/or smaller for the
sections 34, 32, 36, 30, 38 to thereby produce increased
restriction to flow through the sections.
[0045] Although the passage 26 is depicted in FIG. 4 as being
centrally located in the tubular structure 20, it should be
understood that the passage may be otherwise positioned, and
multiple passages may be provided, in keeping with the principles
of the invention.
[0046] Referring additionally now to FIG. 5, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, each of the
sections 30, 32, 34, 36, 38 is made of a mesh or woven filter
material, but instead of using varying numbers of layers to vary
the restriction to flow through the sections, other characteristics
of the material are changed.
[0047] For example, the section 34 may have a finer or denser weave
as compared to the sections 32, 36, thereby increasing the
restriction to flow through the section 34. As described above,
other characteristics of the filter material may be changed to
produce different restrictions to flow through any of the sections
30, 32, 34, 36, 38.
[0048] Another difference in the well screen 16 as depicted in FIG.
5 is that the shroud 46 has an even distribution of the openings
48. This arrangement of the openings 48 may be useful where a
corresponding even distribution of flow through the filter assembly
22 is desired.
[0049] Referring additionally now to FIG. 6, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. This configuration is similar in many
respects to the configuration depicted in FIG. 5, except that the
passage 26 is positioned toward one end of the tubular structure
20, and only three of the sections 30, 32, 34 are used, with the
most restrictive section 34 positioned overlying the passage.
[0050] Although three of the sections 30, 32, 34 are used in the
configuration of FIG. 6, and five of the sections 30, 32, 34, 36,
38 are used in other configurations described above, it should be
understood that any number of sections may be used in keeping with
the principles of the invention. Furthermore, the sections 30, 32,
34, 36, 38 have been described above as providing a series of
discrete increments in changing flow restrictions, but it should be
understood that the restriction to flow could vary in a continuous
manner between sections of the filter assembly, without departing
from the principles of the invention.
[0051] Referring additionally now to FIG. 7, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, the filter
assembly 22 has a restriction to flow which varies continuously
along its length.
[0052] Specifically, the filter assembly 22 as depicted in FIG. 7
is made up of a longitudinally distributed series of elements 50
which extend circumferentially about the tubular structure 20. The
filter assembly 22 may be of the type known as "wire-wrapped," in
which case the elements 50 may be triangular or trapezoidal shaped
cross-section wire. The elements 50 may be individual wraps of the
wire, in which case the elements may be included in the same wire,
or the elements could be separately formed.
[0053] In the section 34 of the filter assembly 22 overlying the
passage 26, a spacing S.sub.1 between the elements 50 is relatively
small (or even zero), thereby providing an increased resistance to
flow through the section. In the section 32, the spacing S.sub.2
between the elements 50 is increased, thereby providing a reduced
resistance to flow as compared to the section 34. In the section
30, the spacing S.sub.3 between the elements 50 is further
increased, thereby providing a reduced resistance to flow as
compared to the section 32.
[0054] It will be appreciated that the spacing between the elements
50 may be varied in any manner along the length of the filter
assembly 22 to produce corresponding restrictions to flow and
distributions of flow through the filter assembly. For example, the
spacing between the elements 50 may be varied linearly,
exponentially, or according to any other function along the length
of the filter assembly 22. The varied spacing between the elements
50 may be designed to produce an even or uneven distribution of
flow through the filter assembly 22. The varied spacing between the
elements 50 may be continuous or in discrete increments. Thus, it
should be understood that any manner of varying the spacing between
the elements 50 may be used in keeping with the principles of the
invention.
[0055] Although the passage 26 is depicted in FIG. 7 as being
positioned toward one end of the tubular structure 20, the passage
may be otherwise positioned, and any number of passages may be
provided. If, for example, the passage 26 is positioned at a middle
of the tubular structure 20, the spacing between the elements 50
could decrease progressively from each end of the filter assembly
22 toward the middle. Thus, it is not necessary for the spacing
between the elements 50 to only increase or decrease in a certain
direction in the filter assembly 22.
[0056] Referring additionally now to FIG. 8, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, a device 52 of
the type known to those skilled in the art as an "inflow control
device" is used to restrict the flow of fluid into the interior of
the tubular structure 20 after the fluid has flowed through the
filter assembly 22.
[0057] Many different types of inflow control devices are
available. The device 52 includes multiple nozzles or orifices 54
in communication with a chamber 56 at one end of the filter
assembly 22. Thus, the passage 26 extends through the orifices 54
and the chamber 56.
[0058] Other types of inflow control devices include helical or
otherwise labyrinthine passages, tubes, etc. Any type of inflow
control device may be used for the device 52 in keeping with the
principles of the invention.
[0059] Note that, in this configuration of the well screen 16, the
filtering portion of the filter assembly 22 does not directly
overlie the passage 26. Nevertheless, the filter assembly 22 may
still have a restriction to flow which increases in a direction
toward the passage 26, for example, to reduce erosion of the
elements 50 adjacent the device 52.
[0060] Referring additionally now to FIG. 9, another alternate
configuration of the well screen 16 is schematically and
representatively illustrated. In this configuration, the tubular
structure 20 and the filter assembly 22 are each made up of
multiple longitudinal sections which allow very long lengths of the
well screen to be assembled during installation in a well.
[0061] The various sections of the tubular structure 20 are
preferably attached to each other using flush threaded joints 58.
The flush joints 58 are conveniently joined during installation
using conventional rig equipment, and the joints conserve radial
space in the well screen 16.
[0062] The various sections of the filter assembly 22 are also
preferably attached to each other using flush threaded joints 60.
The flush joints 60 provide for convenient arrangement of the
sections of the filter assembly 22, so that the distribution of
flow restriction along the filter assembly may be changed as
desired. Alternatively, other attachment methods (such as welding,
bonding, fastening, etc.) may be used for the joints 58, 60, if
desired.
[0063] Of course, a person skilled in the art would, upon a careful
consideration of the above description of representative
embodiments of the invention, readily appreciate that many
modifications, additions, substitutions, deletions, and other
changes may be made to these specific embodiments, and such changes
are within the scope of the principles of the present invention.
Accordingly, the foregoing detailed description is to be clearly
understood as being given by way of illustration and example only,
the spirit and scope of the present invention being limited solely
by the appended claims and their equivalents.
* * * * *