US20070246212A1

US20070246212A1 - Well screens having distributed flow

Info

Publication number: US20070246212A1
Application number: US11/410,996
Authority: US
Inventors: William Richards
Original assignee: Halliburton Energy Services Inc
Current assignee: Halliburton Energy Services Inc
Priority date: 2006-04-25
Filing date: 2006-04-25
Publication date: 2007-10-25
Also published as: NO20072041L; GB2437641A; GB0707949D0; SG136922A1

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.

Description

BACKGROUND

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.
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.
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.
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

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.
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.
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.
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.
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

FIG. 1 is a schematic partially cross-sectional view of a well system embodying principles of the present invention;
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;
FIG. 3 is a schematic quarter-sectional view of a first alternate construction of the well screen;
FIG. 4 is a schematic quarter-sectional view of a second alternate construction of the well screen;
FIG. 5 is a schematic quarter-sectional view of a third alternate construction of the well screen;
FIG. 6 is a schematic quarter-sectional view of a fourth alternate construction of the well screen;
FIG. 7 is a schematic quarter-sectional view of a fifth alternate construction of the well screen;
FIG. 8 is a schematic quarter-sectional view of a sixth alternate construction of the well screen; and
FIG. 9 is a schematic quarter-sectional view of a seventh alternate construction of the well screen.

DETAILED DESCRIPTION

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
In the section 34 of the filter assembly 22 overlying the passage 26, a spacing S₁between 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 S₂between the elements 50 is increased, thereby providing a reduced resistance to flow as compared to the section 34. In the section 30, the spacing S₃between the elements 50 is further increased, thereby providing a reduced resistance to flow as compared to the section 32.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

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.