SAND CONTROL SCREEN ASSEMBLY HAVING A
COMPLIANT DRAINAGE LAYER
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates, in general, to equipment utilized in conjunction with
operations performed in subterranean wells and, in particular, to a sand control screen
assembly having a compliant drainage layer.
BACKGROUND OF THE INVENTION
[0002] Without limiting the scope of the present invention, its background will be
described with reference to producing fluid from a hydrocarbon bearing subterranean
formation, as an example.
[0003] Since the beginning of oil production from subsurface formations, the industry
has been concerned with efficient control of the movement of unconsolidated formation
particles, such as sand, into the wellbore. For example, such formation movement commonly
occurs during production from completions in loose sandstone or following hydraulic fracture
of a formation. Production of these materials causes numerous problems in the operation of
oil, gas or water wells. These problems include plugged formations, tubing and subsurface
flow lines, as well as erosion of casing, downhole equipment and surface equipment. These
problems lead to high maintenance costs and unacceptable well downtime. Accordingly,
numerous methods have been utilized to control the movement of these unconsolidated
formation particles during the production of fluids.
[0004] In one such method, sand control screen assemblies are interconnected within
the completion string. The sand control screen assemblies are designed to allow fluid flow
therethrough but prevent the flow of particulate materials of a predetermined size from
passing therethrough. There are numerous types of filter media that are used for such sand
control screen assemblies including wire wrapped screens, prepacked screens, wire mesh
screens and the like. It has been found that certain screen designs benefit from having a
drainage layer between the filter medium and the base pipe of the sand control screen
assembly. In one such design, the drainage layer may be formed using conventional wire
wrap techniques wherein a wrap wire is wrapped around and welded to a plurality of
longitudinally extending ribs such that the wrap wire forms a plurality of turns around the
ribs having gaps therebetween. A multilayer wire mesh filter medium, preferably including a
protective outer shroud, may be disposed around the wire wrapped drainage layer to form a
sand control screen jacket which may be installed on the base pipe. Once installed on the
base pipe, the ribs provide certain strength to the wire wrap and stand-off between the wire
wrap and the base pipe for fluid cross flow.
[0005] It has been found, however, that such sand control screen assemblies have
suffered from collapse failures in the wire mesh filter medium when the wrap wire of the
drainage layer begins to spread apart and cannot adequately support the wire mesh at
increased pressures. A primary cause of wrap wire spreading is wrinkling or buckling
forming along the length of the wire wrap support structure which occurs as the wrap wire
begins to conform to the outer diameter of the base pipe. Once wrap wire spreading occurs in
the drainage layer, support is lost for the wire mesh filter medium which has led to tearing or
other collapse damage to the wire mesh filter medium allowing particle infiltration
therethrough.
[0006] Accordingly, a need has arisen for a sand control screen assembly that is capable
of filtering fines out of a production stream from a subterranean hydrocarbon bearing
formation. A need has also arisen for such a sand control screen assembly that is simple and
cost-effective to manufacture and that is capable of withstanding severe downhole conditions
during installation and operation. Further, a need has arisen for such a sand control screen
assembly that does not suffer from collapse failures at increased pressures.
SUMMARY OF THE INVENTION
[0007] The present invention disclosed herein comprises a sand control screen
assembly for preventing the inflow of formation particles during production. The sand
control screen assembly of the present invention allows for compliant movement of a
drainage layer under high-pressure conditions while maintaining the integrity of the
underlying structure. In addition, the sand control screen assembly of the present invention is
simple and cost-effective to manufacture and is capable of withstanding severe downhole
conditions during installation and production.
[0008] In one aspect, the present invention is directed to a sand control screen assembly
including a base pipe having at least one opening in a sidewall thereof and a screen jacket
positioned about the base pipe. The screen jacket includes a drainage layer and a filtermedium positioned about the drainage layer. The drainage layer includes a plurality of
circumferentially distributed axially extending ribs and a wrap wire positioned around the
ribs forming a plurality of turns having gaps therebetween. The ribs includes a plurality of
first ribs having a first cross-sectional rib profile shaped and sized to maintain an annular
space between the wrap wire and the base pipe and a plurality of second ribs having a second
cross-sectional rib profile shaped and sized to provide for a gap between the second ribs and
the base pipe.
[0009] In one embodiment, the screen jacket is positioned about a perforated section of
the base pipe. In another embodiment, the screen jacket is positioned about a nonperforated
section of the base pipe. In a further embodiment, the filter medium may be a wire mesh
filter medium.
[0010] In one embodiment, the first ribs have a generally-trapezoidal cross-sectional rib
profile and the second ribs have a circular cross-sectional rib profile. In another embodiment,
the first ribs have a generally-trapezoidal cross-sectional rib profile and the second ribs have
a rectangular cross-sectional rib profile. In certain embodiments, at least one second rib is
circumferentially located between each adjacent pair of first ribs. In other embodiments, at
least two second ribs are circumferentially located between each adjacent pair of first ribs.
[0011] In another aspect, the present invention is directed to a sand control screen
assembly including a base pipe having at least one opening in a sidewall thereof and a screen
jacket positioned about the base pipe. The screen jacket includes a drainage layer and a filter
medium positioned about the drainage layer. The drainage layer includes a plurality of
circumferentially distributed axially extending ribs and a wrap wire positioned around the
ribs forming a plurality of turns having gaps therebetween. The ribs include a plurality of
first ribs and a plurality of second ribs. The first ribs have a nominal diameter in the radial
direction that is greater than a nominal diameter in the radial direction of the second ribs to
provide for a gap between the second ribs and the base pipe.
[0012] In a further aspect, the present invention is directed to a screen jacket for
positioning around a base pipe to form a sand control screen assembly. The screen jacket
includes a plurality of circumferentially distributed axially extending ribs and a wrap wire
positioned around the ribs forming a plurality of turns having gaps therebetween. The ribs
include a plurality of first ribs and a plurality of second ribs. The first ribs have a nominal
diameter in the radial direction that is greater than a nominal diameter in the radial direction
of the second ribs.BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of the features and advantages of the present
invention, reference is now made to the detailed description of the invention along with the
accompanying figures in which corresponding numerals in the different figures refer to
corresponding parts and in which:
[0014] Figure 1 is a schematic illustration of a well system operating a plurality of sand
control screen assemblies according to an embodiment of the present invention;
[0015] Figure 2 is a quarter sectional view, partial cutaway, of a sand control screen
assembly according to an embodiment of the present invention;
[0016] Figures 3A-3B are quarter sectional views of adjacent axial sections of a sand
control screen assembly according to an embodiment of the present invention;
[0017] Figures 4A-4B are cross-sectional views of a sand control screen assembly
according to an embodiment of the present invention;
[0018] Figures 5A-5B are cross-sectional views of a sand control screen assembly
according to an embodiment of the present invention; and
[0019] Figures 6A-6B are cross-sectional views of a sand control screen assembly
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] While the making and using of various embodiments of the present invention
are discussed in detail below, it should be appreciated that the present invention provides
many applicable inventive concepts which can be embodied in a wide variety of specific
contexts. The specific embodiments discussed herein are merely illustrative of specific ways
to make and use the invention, and do not delimit the scope of the present invention.
[0021] Referring initially to figure 1, therein is depicted a well system including a
plurality of sand control screen assemblies embodying principles of the present invention that
is schematically illustrated and generally designated 10. In the illustrated embodiment, a
wellbore 12 extends through the various earth strata. Wellbore 12 has a substantially vertical
section 14, the upper portion of which has cemented therein a casing string 16. Wellbore 12
also has a substantially horizontal section 18 that extends through a hydrocarbon bearing
subterranean formation 20. As illustrated, substantially horizontal section 18 of wellbore 12
is open hole.[0022] Positioned within wellbore 1 and extending from the surface is a tubing string
22. Tubing string 22 provides a conduit for formation fluids to travel from formation 20 to
the surface. At its lower end, tubing string 22 is coupled to a completions string that has been
installed in wellbore 12 and divides the completion interval into various production intervals
adjacent to formation 20. The completion string includes a plurality of sand control screen
assemblies 24, each of which is positioned between a pair of packers 26 that provides a fluid
seal between the completion string 22 and wellbore 12, thereby defining the production
intervals. Sand control screen assemblies 24 serve the primary functions of filtering
particulate matter out of the production fluid stream and may also include flow control
capabilities or other additional functionality.
[0023] Even though figure 1 depicts the sand control screen assemblies of the present
invention in an open hole environment, it should be understood by those skilled in the art that
the present invention is equally well suited for use in cased wells. Also, even though figure 1
depicts one sand control screen assembly in each production interval, it should be understood
by those skilled in the art that any number of sand control screen assemblies of the present
invention may be deployed within a production interval without departing from the principles
of the present invention. Further, even though figure 1 depicts each sand control screen
assemblies as having a single screen jacket, it should be understood by those skilled in the art
that any number of screen jackets may be installed on a single sand control screen assembly
of the present invention without departing from the principles of the present invention.
[0024] In addition, even though figure 1 depicts the sand control screen assemblies of
the present invention in a horizontal section of the wellbore, it should be understood by those
skilled in the art that the present invention are equally well suited for use in deviated
wellbores, vertical wellbores, multilateral wellbore and the like. Accordingly, it should be
understood by those skilled in the art that the use of directional terms such as above, below,
upper, lower, upward, downward, uphole, downhole and the like are used in relation to the
illustrative embodiments as they are depicted in the figures, the upward direction being
toward the top of the corresponding figure and the downward direction being toward the
bottom of the corresponding figure, the uphole direction being toward the surface of the well
and the downhole direction being toward the toe of the well.
[0025] Referring next to figure 2, therein is depicted a quarter sectional view of a sand
control screen assembly according to the present invention that is representatively illustrated
and generally designated 100. Sand control screen assembly 100 may be suitably coupled toother similar sand control screen assemblies, production packers, locating nipples, production
tubulars or other downhole tools to form a completions string such as that described above.
Sand control screen assembly 100 includes a base pipe 102 that including a plurality of
production ports or openings 104. Positioned around the illustrated portion of base pipe 102
is a screen jacket 106 that serves as a filter medium designed to allow fluids to flow
therethrough but prevent particulate matter of a predetermined size from flowing
therethrough. Even though figure 2 depicts sand control screen assembly 100 with a single
screen jacket 106, those skilled in the art will recognize that the sand control screen
assemblies of the present invention could have additional screen jackets positioned around
additional perforated sections of a base pipe with departing from the principles of the present
invention.
[0026] In the illustrated embodiment, screen jacket 106 includes a drainage layer 108
formed from a plurality of circumferentially distributed axially extending ribs 110 having a
screen wire 112 wrapped around ribs 110 forming a plurality of turns having gaps
therebetween. Drainage layer 108 provides stand-off for fluid cross flow between a wire
mesh filter medium 114 and base pipe 102. Wire mesh filter medium 114 is preferably
formed from a fluid-porous, particulate restricting, metal material such as a plurality of layers
of a wire mesh that are sintered, diffusion bond or otherwise operably associated with one
another to form a wire mesh screen. In the illustrated embodiment, wire mesh filter medium
112 has three wire mesh layers 116, 118, 120, however, those skilled in the art will recognize
that wire mesh filter medium 114 could have other numbers of wire mesh layers both greater
than or less than three without departing from the principles of the present invention.
[0027] Positioned around wire mesh filter medium 114 is a protective outer shroud 122
having an array of regularly-spaced perforations 124 passing therethrough. Outer shroud 122
also has a plurality of dimples 126 that provide stand-off between the inner surface of outer
shroud 122 and the outer surface of wire mesh filter medium 114. In the illustrate
embodiment, screen jacket 106 is attached to base pipe 102 by a pair of connector rings 128,
130 that are welded to outer shroud 122 and base pipe 102. Even though welded connections
are depicted and described in figure 2, those skilled in the art will understand that connector
rings 128, 130 could be coupled to outer shroud 122, base pipe 102 or both by other means
including, but not limited to, mechanical connections, sand tight friction fit connections or the
like.[0028] The present invention is characterized in such a manner that the array of
circumferentially distributed axially extending ribs 114 comprises at least a first set of ribs
132 having certain characteristics and a second set of ribs 134 having different
characteristics. For example, the first set of ribs 132 may have a larger nominal diameter in
the radial direction of sand control screen assembly 100 than the second set of ribs 134. As
another example, the first set of ribs 132 may have a different cross sectional shape than the
second set of ribs 134. Preferably, the first set of ribs 132 provides a different stand-off
dimension than the second set of ribs 134, as described in further detail below.
[0029] Referring next to figures 3A and 3B, therein are depicted axially-adjacent
quarter sectional views of a sand control screen assembly according to the present invention
that is representatively illustrated and generally designated 200. As with sand control screen
100 described above, sand control screen assembly 200 may be suitably coupled to other
similar sand control screen assemblies, production packers, locating nipples, production
tubulars or other downhole tools to form a completions string such as that described above.
Sand control screen assembly 200 includes a base pipe 202 having a perforated section 204
and a nonperforated section 206. Positioned around nonperforated section 206 of base pipe
202 is a screen jacket 208 that serves as a filter medium designed to allow fluids to flow
therethrough but prevent particulate matter of a predetermined size from flowing
therethrough.
[0030] In the illustrated embodiment, screen jacket 208 includes a drainage layer 210
formed from a plurality of circumferentially distributed axially extending ribs 212 having a
screen wire 214 wrapped around ribs 212 forming a plurality of turns having gaps
therebetween. Drainage layer 210 provides stand-off for fluid cross flow between a wire
mesh filter medium 216 and base pipe 202. Wire mesh filter medium 216 is preferably
formed from a fluid-porous, particulate restricting, metal material such as a plurality of layers
of a wire mesh that are sintered, diffusion bond or otherwise operably associated with one
another to form a wire mesh screen. In the illustrated embodiment, wire mesh filter medium
216 has three wire mesh layers 218, 220, 222.
[0031] Positioned around wire mesh filter medium 216 is a protective outer shroud 224
having an array of regularly-spaced perforations 226 passing therethrough. Outer shroud 224
also has a plurality of dimples 228 that provide stand-off between the inner surface of outer
shroud 224 and the outer surface of wire mesh filter medium 216. In the illustrate
embodiment, screen jacket 208 is attached to base pipe 202 by a pair of connector rings 230,232 that are welded to outer shroud 224 and base pipe 202. In contrast to the embodiment
shown above in figure 2, in which filtered fluid passes through ports 104 disposed in the wall
of base pipe 102 behind screen jacket 106, filtered fluid travels via an alternate path within
sand control screen assembly 200. In the illustrated embodiment, fluid flows through one or
more openings in connector ring 232 or between the outside of base pipe 202 and the inside
connector ring 232 into annulus 234 between an outer housing 236 and base pipe 202.
Thereafter, the fluid enters the interior of base pipe 202 via ports 238 disposed in the adjacent
section of base pipe 202 depicted in figure 3B. Sand control screen assembly 200 may
include one or more flow control devices (not pictured) disposed within annulus 234 to
control the rate of fluid flow therethrough.
[0032] As discussed above, the present invention is characterized in such a manner that
the array of circumferentially distributed axially extending ribs 212 comprises at least a first
set of ribs 240 having certain characteristics and a second set of ribs 242 having different
characteristics. For example, the first set of ribs 240 may have a larger nominal diameter in
the radial direction than the second set of ribs 242. As another example, the first set of ribs
240 may have a different cross sectional shape than the second set of ribs 242. Preferably,
the first set of ribs 240 provides a different stand-off dimension than the second set of ribs
242, as described in further detail below.
[0033] The following figures depict cross-sections of several sand control screen
assemblies according to alternate embodiments thereof, each including ribs having various
characteristics. These figures depict certain particular embodiments and combinations, but
those of skill in the art will understand and appreciate that the particular shapes and patterns
depicted in the figures are intended only for illustrative purposes, and that many other shapes,
features and patterns may be employed in further alternate embodiments.
[0034] Figure 4A depicts a cross-section of screen assembly 300 showing base pipe 302
having a drainage layer 304 of a sand control screen jacket depicted therearound. Drainage
layer 304 includes an array of circumferentially distributed axially extending ribs 306 with a
wrap wire screen 308 positioned therearound. The array of ribs 306 comprises a first set of
ribs 310 and a second set of ribs 312. Each of ribs 310 has a cross-sectional profile
characterized by a generally-trapezoidal shape. Those of skill in the art will appreciate that a
wide variety of shapes may be employed in place of the generally-trapezoidal shape depicted,
including, but not limited to, round, oval, square, rectangular, triangular, polygonal, arcuate
and compliant shapes, as examples. The broader inwardly-disposed surface of each rib 310faces and contacts the outer surface of base pipe 302, while the narrower outwardly-disposed
surface of each rib 310 is secured to wrap wire 308 by a suitable method of attachment, such
as by welding.
[0035] Each of ribs 312 has a cross-sectional profile characterized by a round shape.
As above, a wide variety of shapes may be employed in place of the round shape depicted.
The outwardly-disposed surface of each rib 312 is secured to wrap wire 308 by a suitable
method of attachment, such as by welding. The nominal diameter of ribs 312 in the radial
direction relative to the nominal diameter of ribs 310 in the radial direction is such that a gap
is formed between the inwardly-facing surface of ribs 312 and the outer surface of base pipe
302. The gap allows for an increased level of compliance and flexibility in the drainage layer
304 that prevents wrinkling, buckling and spreading of wrap wire 308, thereby preventing
collapse of the wire mesh filter medium (not pictured) disposed about drainage layer 302
under increased pressures. This design allows a certain amount of radial movement of wrap
wire 308 toward base pipe 302 between adjacent pairs of ribs 310 but prevents excessive
radial movement due to the presence of ribs 312 between adjacent ribs 310 which not only
limits the extend of the radial movement, thereby ensuring a cross flow path for production
fluids, as best seen in figure 4B, but also provides additional support in the longitudinal
direction to the various turns of wrap wire 308.
[0036] Those of skill in the art will understand and appreciate that the specific details
shown in figures 4A-4B are provided only for purposes of illustration of the inventive
concept embodied therein. As an example, figures 4A-4B depict eight ribs 310 and eight ribs
312 evenly spaced intermittently and circumferentially about base pipe 302 in a one-to-one
relationship, but there is nothing whatsoever within the broader spirit and scope of the present
invention limiting the ribs to this particular number or relationship. In alternate
embodiments, there may be more or fewer than eight ribs 310 or ribs 312, and there may be
more than one rib 310 disposed between each pair of ribs 312. Alternately, there may be
more than one rib 310 disposed between each pair of ribs 312. In certain embodiments, there
may be more than two types of ribs, each type having different characteristics from the
others. In other embodiments, the ribs may not be evenly spaced about the circumference of
base pipe 302. These variations and others are squarely within the general spirit and scope of
the present invention, as will be readily ascertained by one of skill in the art.
[0037] Figure 5A depicts a cross-section of screen assembly 400 showing base pipe 402
having a drainage layer 404 of a sand control screen jacket depicted therearound. Drainagelayer 404 includes an array of circumferentially distributed axially extending ribs 406 with a
wrap wire screen 408 positioned therearound. The array of ribs 406 comprises a first set of
ribs 410 and a second set of ribs 412. Each of ribs 410 has a cross-sectional profile
characterized by a generally-trapezoidal shape. The broader inwardly-disposed surface of
each rib 410 faces and contacts the outer surface of base pipe 402, while the narrower
outwardly-disposed surface of each rib 410 is secured to wrap wire 408 by a suitable method
of attachment, such as by welding.
[0038] Each of ribs 412 has a cross-sectional profile characterized by a rectangular
shape. The outwardly-disposed surface of each rib 412 is secured to wrap wire 408 by a
suitable method of attachment, such as by welding. The nominal diameter of ribs 412 in the
radial direction relative to the nominal diameter of ribs 410 in the radial direction is such that
a gap is formed between the inwardly-facing surface of ribs 412 and the outer surface of base
pipe 402. The gap allows for an increased level of compliance and flexibility in the drainage
layer 404 that prevents wrinkling, buckling and spreading of wrap wire 408, thereby
preventing collapse of the wire mesh filter medium (not pictured) disposed about drainage
layer 402 under increased pressures. This design allows a certain amount of radial movement
of wrap wire 408 toward base pipe 402 between adjacent ribs 410 but prevents excessive
radial movement due to the presence of ribs 412 between adjacent pairs of ribs 410 which not
only limits the extend of the radial movement, thereby ensuring a cross flow path for
production fluids, as best seen in figure 5B, but also provides additional support in the
longitudinal direction to the various turns of wrap wire 408.
[0039] Figure 6A depicts a cross-section of screen assembly 500 showing base pipe 502
having a drainage layer 504 of a sand control screen jacket depicted therearound. Drainage
layer 504 includes an array of circumferentially distributed axially extending ribs 506 with a
wrap wire screen 508 positioned therearound. The array of ribs 506 comprises a first set of
ribs 510 and a second set of ribs 512. Each of ribs 510 has a cross-sectional profile
characterized by a generally-trapezoidal shape. The broader inwardly-disposed surface of
each rib 510 faces and contacts the outer surface of base pipe 502, while the narrower
outwardly-disposed surface of each rib 510 is secured to wrap wire 508 by a suitable method
of attachment, such as by welding.
[0040] Each of ribs 512 has a cross-sectional profile characterized by a round shape.
The outwardly-disposed surface of each rib 512 is secured to wrap wire 508 by a suitable
method of attachment, such as by welding. Although the cross-sectional profiles of the ribs510, 512 are similar to ribs 310, 312 shown in figure 4A, the embodiment shown in figure 6A
differs in that there are multiple ribs 512 disposed between each pair of ribs 510. The
nominal diameter of ribs 512 in the radial direction relative to the nominal diameter of ribs
510 in the radial direction is such that a gap is formed between the inwardly-facing surface of
ribs 512 and the outer surface of base pipe 502. The gap allows for an increased level of
compliance and flexibility in the drainage layer 504 that prevents wrinkling, buckling and
spreading of wrap wire 508, thereby preventing collapse of the wire mesh filter medium (not
pictured) disposed about drainage layer 502 under increased pressures. This design allows a
certain amount of radial movement of wrap wire 508 toward base pipe 502 between adjacent
ribs 510 but prevents excessive radial movement due to the presence of the pair of ribs 512
between adjacent pairs of ribs 510 which not only limits the extend of the radial movement,
thereby ensuring a cross flow path for production fluids, as best seen in figure 6B, but also
provides additional support in the longitudinal direction to the various turns of wrap wire
508.
[0041] While this invention has been described with reference to illustrative
embodiments, this description is not intended to be construed in a limiting sense. Various
modifications and combinations of the illustrative embodiments as well as other
embodiments of the invention will be apparent to persons skilled in the art upon reference to
the description. It is, therefore, intended that the appended claims encompass any such
modifications or embodiments

We claim:
1. A sand control screen assembly having a compliant drainage layer
and comprising:
a base pipe having at least one opening in a sidewall thereof; and
a screen jacket positioned about the base pipe, the screen jacket including
a drainage layer and a filter medium positioned about the drainage layer, the
drainage layer including a plurality of circumferentially distributed axially
extending ribs and a wrap wire positioned around the ribs forming a plurality of
turns having gaps therebetween, the ribs including a plurality of first ribs having
a first cross-sectional rib profile shaped and sized to maintain an annular space
between the wrap wire and the base pipe and a plurality of second ribs having a
second cross-sectional rib profile shaped and sized to provide for a gap between
the second ribs and the base pipe.
2. A sand control screen assembly as claimed in claim 1 wherein the
screen jacket is positioned about a perforated section of the base pipe.
3. A sand control screen assembly as claimed in claim 1 wherein the
screen jacket is positioned about a non-perforated section of the base pipe.
4. A sand control screen assembly as claimed in claim 1 wherein the
filter medium further comprises a wire mesh filter medium.
5. A sand control screen assembly as claimed in claim 1 wherein the
first ribs have a generally-trapezoidal cross-sectional rib profile and the second
ribs have a circular cross-sectional rib profile.
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6. A sand control screen assembly as claimed in claim 1 wherein the
first ribs have a generally-trapezoidal cross-sectional rib profile and the second
ribs have a rectangular cross-sectional rib profile.
7. A sand control screen assembly as claimed in claim 1 wherein at
least one second rib is circumferentially located between each adjacent pair of
first ribs.
8. A sand control screen assembly as claimed in claim 1 wherein at
least two second ribs are circumferentially located between each adjacent pair of
first ribs.
9. A sand control screen assembly comprising:
a base pipe having at least one opening in a sidewall thereof; and
a screen jacket positioned about the base pipe, the screen jacket including
a drainage layer and a filter medium positioned about the drainage layer, the
drainage layer including a plurality of circumferentially distributed axially
extending ribs and a wrap wire positioned around the ribs forming a plurality of
turns having gaps therebetween, the ribs including a plurality of first ribs and a
plurality of second ribs, the first ribs have a nominal diameter in the radial
direction that is greater than a nominal diameter in the radial direction of the
second ribs to provide for a gap between the second ribs and the base pipe.
10. A sand control screen assembly as claimed in claim 9 wherein the
screen jacket is positioned about a perforated section of the base pipe.
11. A sand control screen assembly as claimed in claim 9 wherein the
screen jacket is positioned about a nonperforated section of the base pipe.
17
12. A sand control screen assembly as claimed in claim 9 wherein the
filter medium further comprises a wire mesh filter medium.
13. A sand control screen assembly as claimed in claim 9 wherein the
first ribs have a generally-trapezoidal cross-sectional rib profile and the second
ribs have a circular cross-sectional rib profile.
14. A sand control screen assembly as claimed in claim 9 wherein the
first ribs have a generally-trapezoidal cross-sectional rib profile and the second
ribs have a rectangular cross-sectional rib profile.
15. A sand control screen assembly as claimed in claim 9 wherein at
least one second rib is circumferentially located between each adjacent pair of
first ribs.
16. A sand control screen assembly as claimed in claim 9 wherein at
least two second ribs are circumferentially located between each adjacent pair of
first ribs.
17. A screen jacket for positioning around a base pipe to form a sand
control screen assembly, the screen jacket comprising:
a plurality of circumferentially distributed axially extending ribs; and
a wrap wire positioned around the ribs forming a plurality of turns having
gaps therebetween;
wherein the ribs include a plurality of first ribs and a plurality of second
ribs, the first ribs have a nominal diameter in the radial direction that is greater
than a nominal diameter in the radial direction of the second ribs.
18. A screen jacket as claimed in claim 17 wherein the first ribs have a
- 1 8 -
one-to-one relationship with the second ribs.
19. A screen jacket as claimed in claim 17 wherein at least one second
rib is circumferentially located between each adjacent pair of first ribs.
20. A screen jacket as claimed in claim 17 wherein at least two second
ribs are circumferentially located between each adjacent pair of first ribs.