Note: Descriptions are shown in the official language in which they were submitted.
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WELL SCREEN WITH DRAINAGE ASSEMBLY
REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of priority to U.S. Patent
Application No. 12/420,499 filed April 8, 2009, the entire contents of which
are
incorporated herein.
TECHNICAL FIELD
This description relates to filtration apparatus for use in subterranean
wellbores.
BACKGROUND
For centuries, wells have been drilled to extract oil, natural gas, water, and
other fluids from subterranean formations. In extracting the fluids, a
production string
is provided in a wellbore, both reinforcing the structural integrity of the
wellbore, as
well as assisting in extraction of fluids from the well. To allow fluids to
flow into
production string, apertures are often provided in the tubing string in the
section of the
string corresponding with production zones of the well. Although perforations
allow
for ingress of the desired fluids from the formation, these perforations can
also allow
unwanted materials to flow into the well from the surrounding foundations
during
production. Debris, such as formation sand and other particulate, can fall or
be swept
into the tubing together with formation fluid, contaminating the recovered
fluid. Not
only do sand and other particulates contaminate the recovered fluid, this
particulate
can cause many additional problems for the well operator. For example, as the
particulate flows through production equipment, it gradually erodes the
equipment.
Unwanted particulate can block flow passages, accumulate in chambers, and
abrade
components. Repairing and replacing production equipment damaged by
particulate
in-flow can be exceedingly costly and time-consuming, particularly for
downhole
equipment sometimes located several thousand feet below the earth's surface.
Consequently, to guard against particulate from entering production equipment,
while
at the same time preserving sufficient fluid flow pathways, various production
filters
and filtration methods have been developed and employed including gravel packs
and
well screen assemblies.
A number of well screen filtration designs have been employed. A well screen
assembly is a screen of one or more layers installed in the well, capable of
filtering
against passage of particulate of a specified size and larger, such as sand,
rock
fragments and gravel from surrounding gravel packing. The specific design of
the
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well screen can take into account the type of subterranean formation likely to
be
encountered, as well as the well-type.
SUMMARY
An aspect encompasses well screen assembly with an elongate base pipe
having apertures therein. A filtration layer resides around the base pipe. A
drainage
assembly resides between the base pipe and the filtration layer. The drainage
assembly
includes a plurality of elongate risers carried on a mesh. The drainage layer
supports
the filtration layer apart from the elongate base pipe and defines an elongate
passage
between the base pipe and the filtration layer that communicates fluid
laterally
through the drainage assembly.
An aspect encompasses a screen assembly for use in a well. The screen
assembly includes an elongate apertured tubing and a first mesh layer carried
on the
tubing. The screen assembly further includes a second mesh layer between the
first
mesh layer and the apertured tubing and a third, non-woven mesh layer between
the
second mesh layer and the apertured tubing. The third, non-woven mesh layer is
formed from a planar non-woven mesh sheet wrapped into a cylindrical shape.
The
planar sheet has a first plurality of wires oriented in generally the same
direction and
residing in a first plane and a second plurality of wires affixed to the first
plurality of
wires and residing in a second plane.
An aspect encompasses a method of communicating fluids in a well. In the
method particulate is filtered from a fluid with a filtration layer of a well
screen
assembly. The fluid is communicated laterally through the well screen assembly
via
an elongate passage defined in a drainage assembly of the well screen
assembly. The
drainage assembly resides between the filtration layer and a base pipe of the
well
screen assembly and includes a plurality of elongate risers carried on a mesh
that
support the filtration layer apart from the elongate base pipe and define the
elongate
passage.
One or more of the aspects can include some, none or all of the following
features. The plurality of risers can be wires of a second mesh carried by the
first
mentioned mesh. The second mesh can be a non-woven mesh. The plurality of
risers
can be risers that are not arranged in a mesh. The risers can be oriented
substantially
longitudinally with respect to the elongate base pipe and the elongate passage
can
extend substantially the entire length of the drainage assembly unobstructed
by
structures transversely crossing the passage. The risers can define a
plurality of
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elongate passages and the of passages can be substantially parallel to one
another. The
filtration layer can be a wire mesh and the risers can be of a lower gage than
the wires
of the filtration layer wire mesh. The filtration layer can be a wire mesh and
a
greatest dimension between wires of the filtration layer wire mesh can be
smaller than
a greatest dimension between risers of the drainage assembly. The filtration
layer can
be a wire mesh and a greatest dimension between wires of the filtration layer
wire
mesh can be smaller than a greatest dimension between wires of the drainage
assembly mesh. The well screen assembly can include an apertured shroud pipe
around the filtration layer.
DESCRIPTION OF DRAWINGS
FIG. IA is a side cross-sectional view of an example well system including a
plurality of well screen assemblies.
FIG. lB is a side cross-sectional view of an example well screen assembly.
FIG 2A is a perspective view of an example drainage assembly.
FIG. 2B is an axial cross-sectional view taken intermediate the ends of an
example well screen assembly incorporating the drainage assembly of FIG. 2A.
FIG. 2C is a perspective view of an example drainage assembly incorporating
a welded wire mesh.
FIG. 2D is an axial cross-sectional view taken intermediate the ends of an
example well screen assembly incorporating the drainage assembly of FIG. 2C.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
FIG. 1 A illustrates an example well system 10 including a plurality of well
screen assemblies 12. The well system 10 is shown as being a horizontal well,
having
a wellbore 14 that deviates to horizontal or substantially horizontal in the
subterranean
zone of interest 24. A casing 16 is cemented in the vertical portion of the
wellbore
and coupled to a wellhead 18 at the surface 20. The remainder of the wellbore
14 is
completed open hole (i.e., without casing). A production string 22 extends
from
wellhead 18, through the wellbore 14 and into the subterranean zone of
interest 24. A
production packer 26 seals the annulus between the production string 22 and
the
casing 16. The production string 22 operates in producing fluids (e.g., oil,
gas, and/or
other fluids) from the subterranean zone 24 to the surface 20. The production
string
22 includes one or more well screen assemblies 12 (two shown). In some
instances,
the annulus between the production string 22 and the open hole portion of the
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wellbore 14 may be packed with gravel and/or sand (hereinafter referred to as
gravel
packing 26 for convenience). The well screen assemblies 12 and gravel packing
26
allow communication of fluids between the production string 22 and
subterranean
zone 24. The gravel packing 26 provides a first stage of filtration against
passage of
particulate and larger fragments of the formation to the production string 22.
The well
screen assemblies provide a second stage of filtration, and are configured to
filter
against passage of particulate of a specified size and larger into the
production string
22.
Although shown in the context of a horizontal well system 10, well screen
assemblies 12 can be provided in other well configurations, including vertical
well
systems having a vertical or substantial vertical wellbore, multi-lateral well
systems
having multiple wellbores deviating from a common wellbore and/or other well
systems. Also, although described in a production context, well screen
assemblies 12
can be used in other contexts, including injection, well treatment and/or
other
applications.
As shown in FIG. lB example well screen assembly 12 includes an apertured
base pipe 100 (with square, round, slotted and/or other shaped apertures 140)
that
carries well screen layers 105 including a drainage assembly 110. The drainage
assembly 110 includes a standoff layer 120 adjacent, and in some instances
bonded to
(e.g. welded, brazed and/or adhered) and carried by, a support layer 115. In
some
implementations, the standoff layer 120 can be disposed between the support
layer
115 and the base pipe 100 (as shown), between the support layer 115 and other
layers
105 exterior the drainage assembly 110, or a standoff layer 120 can be
disposed both
between the support layer 115 and the base pipe 100 and between the support
layer
115 and other layers 105 surrounding the drainage assembly 110. The drainage
assembly 110 is configured to facilitate passage of fluids laterally through
the well
screen assembly 12, and in certain instances, facilitate passage of fluid
axially along
the length of the well screen assembly 12. For example, standoff layer 120
creates a
standoff between the base pipe 100 and other layers 105, thereby forming
elongate
passageways 122 through which flow of fluid is communicated. In some
implementations, the passageways 122 can be continuous and unobstructed for
the
length (the entire or substantially entire length) of the drainage assembly
110 or for
only a portion of the length of the drainage assembly 110 (e.g., approximately
3/4,
1/2, 1/4, 1/8, 1/16, 1/32 the length or other portion of the length of the
drainage
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assembly). Support layer 115 supports other layers 105 exterior to the support
layer
115 from collapsing into, and thus obstructing or partially obstructing, the
passageways 122 created by the standoff layer 110. Communication of fluids
through the standoff layer 120 can facilitate more uniform distribution of
flow to the
apertures 140 intermediate the ends of the base pipe 100, thus improving fluid
flow
between the interior and exterior of the well screen assembly 12.
Communication of
fluids through the standoff layer 120 can facilitate passage of fluids to the
ends of the
well screen assembly 12. For example, communicating fluids to the ends of the
well
screen assembly 12 may be desirable in instances where flow is communicated
between the well screen layers 105 and the interior of the base pipe 100 at
the ends of
the well screen assembly 12 via a screen valve, inflow control device, and/or
otherwise.
Well screen layers 105 further include a filtration layer 125 that operates as
the primary fine filtering mechanism of the well screen assembly 12, and is
configured to allow flow of fluid and filter against passage of the smallest
particulate
filtered by the well screen assembly 12. The filtration layer 125 can have the
highest
mesh per inch count and/or the smallest apertures therethrough of any the
other well
screen layers 105. Although only one filtration layer 125 is shown, in some
instances,
additional filtration layers can be included and/or the filtration layer can
be
incorporated into the drainage assembly 110 (such as support layer 115). If
multiple
filtration layers 125 are provided, they can each be configured to filter
against passage
of the same size particulate or one or more of the filtration layers 125 can
be
configured to filter against passage of different size particulate.
Well screen assembly 12 includes an outer shroud 130 surrounding the well
screen layers 105 and forming the exterior of the well screen assembly 12 to
protect
and preserve the integrity of the layers beneath. In certain instances, the
outer shroud
layer 130 is an apertured pipe having square, circular, slotted and/or other
shaped
apertures 135 that allow passage fluid through the outer shroud layer 130. The
outer
shroud 130 may perform an initial filtering function, filtering against
passage of larger
particulate into the well screen layers 105 beneath.
Although only a drainage assembly 110 and filtration layer 125 have been
discussed above, the well screen assembly 12 can include additional layers of
additional types and/or additional drainage assemblies 110 and/or filtration
layers 125
can be included beneath the outer shroud 130.
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FIG. 2A illustrates a perspective view of an example drainage assembly 200
having a standoff layer 210 that resides within a support layer 225. The
standoff layer
210 includes a plurality of longitudinal (i.e., parallel or substantially
parallel to the
longitudinal axis of the drainage assembly, and thus well screen assembly)
oriented,
elongate risers 205 bonded to an interior surface 220 of a support layer 225.
The
longitudinally oriented risers 205 form elongate longitudinal passageways 215
therebetween that facilitate passage of fluid longitudinally along the
drainage
assembly 200. The longitudinal passageways, as shown, are continuous for the
length (the entire length or substantially the entire length) of the drainage
assembly
200, and wholly unobstructed by transverse crossing wires or other transverse
structures. Although shown as round wire or rods, risers 205 can may have
cross-
sectional profiles exhibiting a variety of different geometries. For example,
risers 205
can have rectangular, triangular, or other-shaped cross-sections. Also, risers
205 can
be continuous members, or non-continuous members, such as raised nodules
formed
into and/or bonded to the surface of the support layer 225. Although shown as
longitudinal passageways 215, the risers 205 can be arranged to define
passageways
215 in other directions (e.g., circumferential, helical, and/or other).
In some implementations, see for example FIG. 2C, a welded mesh (e.g., a
square welded mesh, and/or other mesh) can be used in lieu of or in addition
to the
plurality of individual risers 205. A welded mesh is a non-woven mesh that
includes a
first plurality of parallel wires 250 oriented in one direction with a second
plurality of
parallel wires 255 welded, brazed and/or otherwise affixed to the first
plurality of
wires, and oriented in a second direction. In a square welded mesh, the first
and
second directions are substantially perpendicular and the spacing between
crossing
wires is substantially equal to define square spaces between the wires.
Typically all of
the first plurality of wires 250 reside on one side of the mesh and all of the
second
plurality of wires 255 reside on the opposite side of the mesh. Welded mesh is
typically pre-manufactured and commercially available formed in a flat sheet,
and
could be rolled into a tubular shape for use as standoff layer 210. For
example, when
the mesh is flat, the first plurality of wires 250 reside entirely in one
plane and the
second plurality of wires 255 reside entirely in a different plane. In some
implementations, the welded mesh may be positioned in the drainage assembly
200
with the wires on the inner surface of the standoff layer 210 oriented
longitudinally
along the drainage assembly 200 (i.e., defining risers) and wires on the outer
surface
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of the standoff layer 210, adjacent the support layer 225, circumferentially
around the
drainage assembly 200. As such, the longitudinally oriented wires of the wire
mesh
define risers 205 and the longitudinal passageways between. The
circumferentially
oriented wires, being on the outside of the mesh, do not obstruct the
longitudinal
passageways. In some implementations, the gage of the wires on the inner
surface of
the standoff layer 210 can be smaller (i.e., larger diameter) than the gage of
the wires
on the outer surface of the standoff layer 210. In some instances, the spacing
between
adjacent wires on the inner surface of wire mesh standoff layer 210 can be
greater
than the spacing between adjacent wires on the outer surface of the wire mesh
standoff layer 210.
Support layer 225 can be a welded and/or woven mesh (e.g., a square welded
mesh, a square woven mesh, and/or other mesh). In certain instances, the mesh
per
inch count of the support layer 225 is higher (i.e., able to filter against
passage of a
smaller particulate) than the mesh per inch count of the standoff layer 210.
In certain
instances, the wire gage of the support layer 225 is higher (i.e., smaller
diameter) than
the wire gage of some or all of the wires in the standoff layer 210. In
certain
instances, the wire gage of warp wires in the standoff layer 210 are larger
than the
warp and/or weft layers of the support layer 225. Of note, the use of the term
"mesh"
herein is used to exclude wrapped wire screen, i.e. a screen formed in a
cylinder by
helically wrapping wire about a plurality of longitudinal wires arranged in a
generally
cylindrical shape.
FIG. 2B is an axial cross-sectional view taken intermediate the ends of an
example well screen assembly 240 incorporating drainage assembly 200 carried
on a
base pipe 230. FIG. 2B also shows the inclusion of a mesh filtration layer 235
and
protective, outer shroud layer 245 in the well screen assembly 240. As is
shown,
risers 205 contact the outer surface of base pipe 230, supporting and
separating the
support layer 225 from the base pipe 230. Risers 205 can be bonded (e.g.,
welded,
brazed, adhered and/or otherwise bonded) to the support layer 225 prior to
wrapping
the support layer 225 (and risers 205) around the base pipe. In other
examples, risers
205 can be bonded to, and positioned around the exterior surface of base pipe
230
prior to the support layer 225 being wrapped around the base pipe 230. The
skeleton
of risers 205 surrounding the base pipe 230 provide an offset h between the
base pipe
230 and support layer 225. Both the offset h and the width w between risers
205 is
greater than the height or width of any other passage in the filtration layer
235.
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Indeed, in other implementations, the base pipe 230 can be manufactured so as
to
form the rib members 205 or other standoff risers, into the structure of the
base pipe
230 itself.
FIG. 2D is an axial cross-sectional view taken intermediate the ends of an
example well screen assembly 240' incorporating welded wire mesh drainage
assembly 200'. The well screen assembly 240' has a similar construction to
well
screen assembly 240, except that the drainage assembly 200' incorporates a
welded
wire mesh as standoff layer 210' .
A number of embodiments of the invention have been described.
Nevertheless, it will be understood that various modifications may be made
without
departing from the spirit and scope of the invention. Accordingly, other
embodiments
are within the scope of the following claims.
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