Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Cementing Sub for Annulus Cementing
Field
The present invention relates to downhole tubulars and, in particular, a
wellbore tubular
device for assisting annulus cementing operations.
Background
Wellbores are often completed by introduction of cement around the tubular in
the
annulus between the tubular and the borehole wall. The cement holds the
tubular in
place in the well and creates isolation by controlling against fluid passage
through the
wellbore annulus from one section of the well to another. Isolation serves the
purpose
of preventing flow of fluids or gas from one section of a well that may be
undesirable
such as water, to a section of the well that would otherwise produce
hydrocarbon.
In addition, certain operations require that fluid be placed into the well at
specific
locations. These operations may include acidizing or hydraulic fracturing. The
cement
in these cases provides isolation by containing the fluid placement to the
desired
locations in the well to produce desired results. If ports are placed along a
tubular string
in the well, either cement or packers can be used to isolate one section of
the well about
one or more ports from one another section. If the ports are cemented in
place, the
cement circulated into the annulus section of the well may cause problems
operating the
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ports. In addition, the ability to inject fluid into the formation through the
ports may
prove difficult because the cement will prevent contact and communication with
the
formation rock. If fracturing is planned, the cement may cause high fracture
initiation
pressures.
When a ported tubular is positioned in a well, cement generally cannot be used
in the
usual way since the cement will block the outside of the port such that
although the port
is opened, fluid treatments are blocked from entering the wellbore because of
the
presence of the cement. If fluid is introduced at a pressure that would
normally fracture
the well, the force of the fluid injection is distributed over a wider area by
the cement
such that the force is dissipated and the treatment may be rendered less than
effective.
Summary
The invention relates to a wellbore tubular for assisting annulus cementing
operations
by allowing some sections of the well to be left uncemented and to provide the
option to
either perforate or to activate or open and close ports within these
uncemented areas.
If ports are used and the annulus surrounding the ports is not cemented, but
the
adjoining areas on each side of the ports contain a cemented annulus, then the
ports,
when opened, will provide direct contact with the formation for production or
fluid
placement (formation stimulation), and the benefits of cement to perform zonal
isolation.
This invention provides a wellbore tubular, a method and a wellbore tubular
installation
to allow cementing of the annulus while leaving the area surrounding the ports
uncemented.
In accordance with a broad aspect of the present invention, there is provided
method for
installing a tubular string in a wellbore, the method comprising: providing a
tubular string
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including an inner bore and an outer surface, an upper annular packer
encircling the
tubular string, a lower annular packer encircling the tubular string below the
upper
annular packer and a conduit extending to provide a fluid tight path from a
conduit first
open end below the lower packer in communication with the outer surface and a
conduit
second open end above the upper packer in communication with the outer
surface;
running the tubular string into the wellbore to create an annulus between the
tubular
string and the wellbore wall; setting the packers to isolate an intermediate
portion of the
annulus from annular regions above the upper packer and below the lower
packer;
pumping cement into the annular regions and through the conduit, such that the
conduit
and the annular regions above the upper packer and below the lower packer
become
filled with cement while the intermediate portion of the annulus is isolated
from
introduction of cement thereto; and allowing the cement to set.
In accordance with another broad aspect of the present invention, there is
provided a
wellbore tubular comprising: a tubular body including a first end, an opposite
end and a
wall defined between an inner bore extending from the first end to the
opposite end and
an outer surface; a port through the wall of the tubular body providing
communication
between the inner bore and the outer surface, the port including an openable
closure; a
conduit along the wall of the tubular extending from an inlet adjacent the
first end and an
outlet adjacent the opposite end, the inlet and outlet opening to the outer
surface and
being isolated from communication with the inner bore; a first annular packer
encircling
the tubular body and positioned between the port and the inlet; and a second
annular
packer encircling the tubular body and positioned between the port and the
outlet.
In accordance with another broad aspect of the present invention, there is
provided a
tubular installation in place in a borehole comprising: a tubing string in a
borehole
creating an annular space between the tubing string and a wall of the
borehole, the
tubing string including a tubular body including a first end, an opposite end
and a wall
defined between an inner bore extending from the first end to the opposite end
and an
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outer surface; a port through the wall of the tubular body, which when open
provides
communication between the inner bore and the outer surface; a conduit along
the wall
of the tubular extending from an inlet adjacent the first end and an outlet
adjacent the
opposite end, the inlet and outlet opening to the outer surface but being
isolated from
communication with the inner bore; a first annular packer encircling the
tubular body and
expanded to seal against communication between the port and the inlet; and a
second
annular packer encircling the tubular body and expanded to seal against
communication
between the port and the outlet, the first packer and the second packer
dividing the
annular space into an upper annular space above the second packer, a middle
annular
space between the first packer and the second packer and a lower annular space
below
the first packer.
It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein
various embodiments of the invention are shown and described by way of
illustration.
As will be realized, the invention is capable for other and different
embodiments and its
several details are capable of modification in various other respects, all
without
departing from the spirit and scope of the present invention. Accordingly the
drawings
and detailed description are to be regarded as illustrative in nature and not
as
restrictive.
Brief Description of the Drawings
Referring to the drawings, several aspects of the present invention are
illustrated by way
of example, and not by way of limitation, in detail in the figures, wherein:
Figure 1 is a schematic sectional view along a portion of a well bore with a
tubular
therein, according to one aspect of the invention.
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Figure 2 is a sectional view along a portion of a well bore with a tubular
string therein.
Figure 3 is a perspective view of a wellbore tubular according to the present
invention.
Figure 4 is a sectional view along the long axis of another wellbore tubular
according to
the present invention.
Description of Various Embodiments
The detailed description set forth below in connection with the appended
drawings is
intended as a description of various embodiments of the present invention and
is not
intended to represent the only embodiments contemplated by the inventor. The
detailed
description includes specific details for the purpose of providing a
comprehensive
understanding of the present invention. However, it will be apparent to those
skilled in
the art that the present invention may be practiced without these specific
details.
With reference to the Figure 1, a wellbore tubular and an installation are
shown
according to various aspects of the present invention.
A wellbore tubular may include tubular body 10 including a first end, an
opposite end
and a wall defined between an inner bore 10a extending from the first end to
the
opposite end and an outer surface 1 Ob; one or more ports 18 through the wall
of the
tubular body providing communication between the inner bore and the outer
surface,
each port including an openable closure 20; a conduit 24 along the wall of the
tubular
extending between openings from the area around the outer surface to the
conduit. For
ease of reference, the openings can be considered to include an inlet 26
adjacent the
first end and an outlet 28 adjacent the opposite end. The inlet and the outlet
open to the
outer surface but are isolated from communication with inner bore 10a of the
tubular. In
this way fluids can pass through the conduit from the inlet to the outlet (or
vice versa)
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along the wall of the tubular without flowing from the conduit out through the
ports
toward the outer surface of the tubular body and without flowing from the
conduit into
the inner diameter of the tubular. As will be appreciated, the port and the
conduit are
out of fluid communication. For example, the conduit may extend along the wall
and the
port may pass through the wall without the port and conduit opening into each
other.
The wellbore tubular further may include a first annular packer 30 encircling
the tubular
body and positioned between port 18 and the inlet 26 and a second annular
packer 36
encircling the tubular body and positioned between the port and outlet 28.
The ports and their openable closures may take various forms. For example, the
openable closures may include burst discs, dissolvable materials, a shearable
cap, a
sliding sleeve valve (as shown), etc.
The conduit may take various forms. For example, the conduit may include one
or more
discreet tubulars attached on or embedded in the tubular body wall, the
tubular body
wall may be formed of thick materials and the conduit may bored axially
therethrough,
the tubular body wall may include a hollow annular space that defines the
conduit, etc.
Likewise, the inlets and outlets may take various forms such as discreet
openings from
the outer surface into the conduit. Alternately, the inlets and outlets may be
defined by
larger open areas such as the full annular opening between inner and outer
tubular
shells forming a hollow wall of the tubular body.
The annular packers may also take various forms. The packers may be
expandable,
inflatable, etc. In one embodiment, the packers are solid body-type packers
such as
including one or more extrudable elements. The extrudable elements may be
driven to
expand by hydraulic swelling or compression drivers. For example, one useful
packer
type may be a hydraulically driven compression set packer such as one
available from
the assignee of this application, under the trade name RocksealTM
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The wellbore tubular may be used to form a tubular installation for placement
in a
wellbore. In such an installation an annular space 40 may be formed between
the
wellbore tubular and a wall 50 of the borehole. Using a wellbore tubular such
as that
described above as an example, the tubular installation may include the
wellbore tubular
placed in the wellbore with the first annular packer and the second annular
packer
expanded. In such an installation, the first packer and the second packer
divide the
annular space into an upper annular space above the second packer, an
intermediate
annular space 40a between the first packer and the second packer and a lower
annular
space below the first packer. When set against a wellbore wall (cased or open
hole),
the first annular packer seals against communication between the port and the
inlet
through the annular space and the second annular packer seals against fluid
communication along the annular space between the port and the outlet.
Such an installation may be employed to affect a method for installing a
tubular string in
a wellbore. According to one embodiment, the method may include first
providing a
tubular including a port extending from an inner bore of the tubular to open
on the outer
surface, an upper annular packer encircling the tubular above the port, a
lower annular
packer encircling the tubular below the port and a conduit extending to
provide a fluid
path from a conduit first open end below the lower packer and a conduit second
open
end above the upper packer. Such a tubular can run into the wellbore, thereby
creating
an annulus between the tubular and a wall of the wellbore. Of course, the
tubular will
likely be installed in a string of tubulars and is run in by running in the
string, by methods
well known in the art. In such an embodiment, the inner bore of the tubular
may be in
communication with the surface through an upper string extending above the
tubular.
Once in position in the wellbore, the packers may be set to isolate an
intermediate
portion of the annulus from regions of the annulus above the upper packer and
below
the lower packer. Thereafter, cement may be pumped (arrows C) into through the
annular regions and through the conduit.
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The conduit allows the cement to pass from the regions below the lower packer
to the
regions above the upper packer without cementing the intermediate annular
region.
Closures on the ports prevent the cement from passing into the intermediate
annular
region through the port. As such the tubular can be annularly cemented into
the
wellbore while leaving the annular area about the port of the tubular open. As
such
fluids can pass from the inner bore of the tubular out into contact with the
wellbore (and
vice versa) without hindrance by cement in the annular region about the port.
It will be appreciated that cement is usually pumped through the tubular inner
bore from
surface to an end of the tubular. Pumping is continued such that the cement
then
moves up through the annular space about the tubular back toward surface.
However,
it is to be understood that the method encompasses, and the wellbore tubular
is useful
for, a procedure where cement is pumped down towards the upper packer and
passes
through the conduit to exit below the lower packer.
After the cement is pumped through the annular space, the cement is allowed to
set as
by holding the cement in the annular space by holding pressure above the
cement or by
use of a cement float. Thereafter, the ports may be opened by, for example,
opening or
removing the closures. Wellbore operations can then begin, for example,
production or
wellbore treatments though the port such as for example by injection of
fracturing fluid,
stimulation fluids, etc.
With reference to Figure 2, a wellbore installation could include a string 60
incorporating
one or, as shown, more of the wellbore tubulars according to the invention
such as, for
example, as shown in any one of Figures 1, 3 or 4 or others not specifically
illustrated.
While two tubulars are shown, the string could include many such tubulars and
possibly
other components. The tubulars include a port 18 extending from an inner bore
1 Oa of
the tubular to open on the outer surface 1 Ob, an upper annular packer 36
encircling the
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tubular above the port, a lower annular packer 30 encircling the tubular below
the port
and a conduit 24 extending to provide fluid communication between the outer
surface
below the lower packer and the outer surface above the upper packer without
opening
into the outer surface between the packers. The inner bores 10a of the
tubulars are
open to the inner diameter 60a of the string 60.
Such a string 60 can run into a wellbore 50, thereby creating an annulus 40
between the
string and the wall of the wellbore. Of course, the tubular will likely be
installed in a
string of tubulars and is run in by running in the string, by methods well
known in the art.
Once in position in the wellbore, the packers may be expanded or allowed to
expand to
isolate an intermediate portion 40a of the annulus from regions of the annulus
above the
upper packers and below the lower packers. Thereafter, cement may be pumped
through the annular regions and through the conduits. In the illustration of
Figure 2, the
cement can be seen, as shown by stippling, in the annular region 40 about the
string but
not in the intermediate portions 40a between the packers of the tubulars. In
this way,
the intermediate portions 40a remain open such that when ports 18 are opened,
fluids
can pass through inner bore 60a of the string, which is continuous with inner
bores 1 Oa
of the tubulars, and out through the ports into contact with the wellbore
without
hindrance by cement in the annular region about the port. Fluids, for example,
may
effect a fracing operation such as that shown wherein fractures 62 are
generated in the
formation about the wellbore.
The ports may be opened by various means such as by tubing manipulation,
bursting,
shearing, etc. For example, the ports may be opened by shearing as disclosed
in
applicant's corresponding US Patent 6,907,936, issued June 21, 2005 or by a
sliding
sleeve type valve as more fully disclosed in applicant's US Patent 7,134,505,
issued
November 14, 2006. Alternately or in addition, the ports may be opened all at
once, as
by use of a hydraulically openable valve as disclosed in applicants
corresponding PCT
application PCT/CA2009/000599, filed April 29, 2009. Alternately, the ports
may be
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opened in stages, as more fully disclosed in applicant's US Patent 7,134,505,
issued
November 14, 2006.
With reference to Figure 3, another wellbore tubular is shown according to
various
aspects of the present invention. This wellbore tubular is shown sectioned
through its
tubular body 110 just below its ports 118. Ends 11 Oc and the other of which
cannot be
seen in this view, include forms, such as threading as shown for connection
into a
tubular string. As will be appreciated, such a tubular is often called a sub.
Ports 118
extend laterally out through the wall of the tubular body providing
communication
between the tubulars inner bore and its outer surface. A sliding sleeve valve
120,
shown partially open in this view, acts as an openable closure for the ports.
A plurality of conduits 124 are formed along the wall of the tubular by
attaching axial
tubular segments to the outer surface of the tubular. The conduits extend from
upper
and lower open ends 128, only one of which can be seen in this view. First and
second
annular packers 132, only one of which can be seen in this view, are installed
about the
tubular. The conduits pass through the packers and along the tubular wall to
provide a
fluid passage along the wall of the tubular without opening to the outer
surface of the
tubular between the packers and or into the inner bore of the tubular.
With reference to Figure 4, yet another wellbore tubular is shown according to
various
aspects of the present invention. This wellbore tubular is shown sectioned
along its
long axis through a port 218. Ends 210c, while shown as blanks, can be formed
to
allow connection of the tubular body 210 into a tubular string. As will be
appreciated,
such a tubular is often called a sub. Port 218 extends laterally out through
the wall of
the tubular body providing communication between the tubular body inner bore
210a
and its outer surface 210b. A sliding sleeve valve 220, in this view shown
closed but in
the process of being opened, acts as an openable closure for the port 218.
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In this illustrated embodiment, the sliding sleeve is moveable remotely from
its closed
port position, substantially as shown, to its position permitting through-port
fluid flow, for
example, without having to run in a line or string for manipulation thereof.
In one
embodiment, the sliding sleeve is actuated by a device, such as a ball 221 (as
shown)
or plug, which can be conveyed by gravity or fluid flow through the tubing
string. The
device, in this case ball 221, engages against the sleeve and, when pressure
is applied
through the inner bore 21 Oa, as from surface through a string to the tool,
ball 221 seats
against and creates a pressure differential above and below the sleeve which
drives the
sleeve toward the lower pressure side.
In the illustrated embodiment, the inner surface of the sleeve which is open
to the inner
bore 21 Oa of the sub defines a seat 223 onto which a suitably sized ball,
when launched
from surface, can land and seal thereagainst. When the ball seals against the
sleeve
seat and pressure is applied or increased from surface, a pressure
differential is set up
which causes the sliding sleeve on which the ball has landed to slide to a
port-open
position. When the port 218 is opened, fluid can flow therethrough to the
annulus
between the tubing string and the wellbore and thereafter into contact with
formation.
A conduit 224 is formed along the wall of the tubular body by attaching an
axial tubular
segment to the outer surface of the tubular. The axial tubular segment can,
for
example, be obtained from a pipe having a radius smaller than the radius of
the
wellbore tubular and a section of the wall of the tubular can be cut along the
tubular's
length substantially parallel to the long axis of the tubular. Alternately,
the axial tubular
segment can be obtained by bending a sheet of material along its length. In
any event,
the axial tubular segment is attached with its concave side facing against the
outer
surface of the wellbore tubular, as by welding, etc. The conduit extends
between open
ends 228, only one of which can be seen in this view. First and second annular
packers
232 are installed about the tubular body. The conduits pass through the
packers, when
they are expanded, and along the tubular wall to provide a fluid passage along
the wall
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of the tubular without opening to the outer surface of the tubular between the
packers
and or into the inner bore of the tubular.
Although other types of packers may be employed, in the illustrated
embodiment,
packers 232 are shown as the type set by hydraulic compression. Such a packer
includes an extrudable packing element 266 carried in an unset condition which
is
driven to extrude by a hydraulically actuated setting mechanism 268. These
parts are
mounted on the tubular body and radially outwardly of the conduit. Element 266
is
formed of an elastomer, such as for example, rubber and may include an
enlarged cross
section to provide excellent expansion ratios to set in oversized holes.
Packing element 266 may be, for example, mounted between a fixed stop ring
268a and
compressing ring 268b. The hydraulically actuated setting mechanism may
include a
port 268c through the tubular body which provides fluid access to a hydraulic
chamber
268d defined behind compressing ring 268b. Compressing ring 268b includes a
piston
face 268e against which the hydraulic pressure in chamber 268d acts to drive
the ring
against the packing element to compress and, therefore, expand it outwardly.
Thus, the packers illustrated in Figure 4 are set by pressuring up the tubing
string such
that fluid enters the hydraulic chamber and acts to drive compression of the
packing
elements, thereby extruding them outwardly. A lock may be provided to act
against
retraction of the packing elements out of the extruded position.
The previous description of the disclosed embodiments is provided to enable
any
person skilled in the art to make or use the present invention. Various
modifications to
those embodiments will be readily apparent to those skilled in the art, and
the generic
principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
consistent
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with the claims, wherein reference to an element in the singular, such as by
use of the
article "a" or "an" is not intended to mean "one and only one" unless
specifically so
stated, but rather "one or more". All structural and functional equivalents to
the
elements of the various embodiments described throughout the disclosure that
are know
or later come to be known to those of ordinary skill in the art are intended
to be
encompassed by the elements of the claims. Moreover, nothing disclosed herein
is
intended to be dedicated to the public regardless of whether such disclosure
is explicitly
recited in the claims. No claim element is to be construed under the
provisions of 35
USC 112, sixth paragraph, unless the element is expressly recited using the
phrase
"means for" or "step for".
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