Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHODOLOGY FOR RUNNING CASING STRINGS
THROUGH A CONDUCTOR TUBE
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present document is based on and claims priority to U.S.
Provisional
Application Serial No.: 61/863,163, filed August 7, 2013, which is
incorporated herein by
reference in its entirety.
BACKGROUND
[0002] Hydrocarbon fluids such as oil and natural gas are obtained from
a
subterranean geologic formation, referred to as a reservoir, by drilling a
well that
penetrates the hydrocarbon-bearing formation. Once a wellbore is drilled,
various forms
of well completion components may be installed to control and enhance
efficiency of
producing the various fluids from the reservoir. One piece of equipment which
may be
installed is a casing which may be deployed in a corresponding, drilled
borehole. In
multilateral wells, multiple casings may be run in their corresponding
boreholes. The
boreholes and casings are oriented to avoid interfering with each other.
SUMMARY
[0003] In general, a methodology and system are provided for
facilitating running
of casing strings in, for example, a multilateral well or system of wells. A
conductor tube
may be placed into a hole formed in a seabed. A plurality of oriented casings
is deployed
in the conductor tube and the oriented casings are arranged with a specific
exit angle and
azimuthal orientation. The orientation of each oriented casing is used to
direct a
corresponding drilling of a borehole and placement of a casing in the borehole
in a
manner which does not interfere with other boreholes and casings.
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[0004] However, many modifications are possible without materially
departing
from the teachings of this disclosure. Accordingly, such modifications are
intended to be
included within the scope of this disclosure as defined in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Certain embodiments of the disclosure will hereafter be described
with
reference to the accompanying drawings, wherein like reference numerals denote
like
elements. It should be understood, however, that the accompanying figures
illustrate the
various implementations described herein and are not meant to limit the scope
of various
technologies described herein, and:
[0006] Figure 1 is a schematic illustration of an example of a platform
used in
cooperation with a plurality of conductor tubes for constructing a
multilateral well,
according to an embodiment of the disclosure;
[0007] Figure 2 is a schematic illustration of an example of a conductor
tube
having internal oriented casings, according to an embodiment of the
disclosure;
[0008] Figure 3 is a schematic illustration of an example of a portion
of an
orientation system for orienting a plurality of oriented casings in a
conductor tube,
according to an embodiment of the disclosure;
[0009] Figure 4 is an illustration of an example of a conductor tube
extending into
a well bay of a well platform, according to an embodiment of the disclosure;
[0010] Figure 5 is an illustration of an example of a module used in
forming a
conductor tube with internal oriented casings, according to an embodiment of
the
disclosure;
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[0011] Figure 6 is a cross-sectional illustration of the module
illustrated in Figure
5, according to an embodiment of the disclosure;
[0012] Figure 7 is a cross-sectional view of a module having dual
oriented
casings, according to an embodiment of the disclosure;
[0013] Figure 8 is an illustration of an example of a centralizer plate
having an
alignment pin which may be employed to align sequential modules, according to
an
embodiment of the disclosure;
[0014] Figure 9 is an illustration of an example of an alignment hole
for receiving
an alignment pin to align sequential modules, according to an embodiment of
the
disclosure;
[0015] Figure 10 is an illustration of an example of sequential
alignment pins of
sequential modules to ensure a desired orientation of the internal oriented
casings,
according to an embodiment of the disclosure;
[0016] Figure 11 is an illustration of an example of a conductor tube
installed in a
hole in a seabed, according to an embodiment of the disclosure;
[0017] Figure 12 is an illustration of an enlarged portion of the
conductor tube
illustrating check valves disposed in the internal oriented casings, according
to an
embodiment of the disclosure;
[0018] Figure 13 is an illustration of sequential modules of oriented
casings being
assembled in a desired alignment, according to an embodiment of the
disclosure; and
[0019] Figure 14 is an illustration of a multilateral well in which a
plurality of
lateral boreholes and corresponding casings have been properly oriented in a
non-
interfering arrangement, according to an embodiment of the disclosure.
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DETAILED DESCRIPTION
[0020] In the following description, numerous details are set forth to
provide an
understanding of some embodiments of the present disclosure. However, it will
be
understood by those of ordinary skill in the art that the system and/or
methodology may
be practiced without these details and that numerous variations or
modifications from the
described embodiments may be possible.
[0021] The present disclosure generally relates to a system and
methodology for
facilitating running of casing strings in, for example, a multilateral well or
system of
multilateral wells. A conductor tube may be placed into a hole formed in a
seabed. A
plurality of oriented casings is arranged in the conductor tube and the
oriented casings
have a specific exit angle and azimuthal orientation. In some embodiments, the
system
and methodology facilitate running of dual casing strings from a dual wellhead
and
through a conductor tube to achieve specific exit angles and azimuthal
orientations. The
orientation of each oriented casing is used to direct a corresponding drilling
of a borehole
and placement of a casing in the borehole in a manner which does not interfere
with other
boreholes and casings. The orientation enables use of a plurality of the
conductor tubes
in cooperation with a platform by controlling the orientation of the multiple
boreholes
and casings of the multilateral well.
[0022] In a specific example, a platform escape strategy is established
by
orienting dual casing strings from dual wellheads located along a platform.
The
technique enables the dual casing strings associated with each dual wellhead
to be
oriented and guided using prefabricated conductor hardware. The prefabricated
conductor hardware, e.g. conductor tube related modules, provides control over
the
specific exit angle and azimuthal orientation of oriented pairs of casings
disposed in
corresponding conductor tubes which extend down to a seabed.
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[0023] Referring generally to Figure 1, an embodiment of a multilateral
well
system 20 is illustrated. In this embodiment, the well system 20 comprises a
platform 22
having a plurality of platform slots 24 for corresponding wellheads 26. Each
wellhead 26
may correspond with a lateral wellbore or a plurality of lateral wellbores
accessed
through oriented casings 28. In some applications, the wellheads 26 may
comprise dual
wellheads which each correspond with a pair of oriented casings 28 extending
to lateral
boreholes formed at a subsea location. In a variety of applications, the
platform 22 may
comprise a gravity based structure constructed for use in hydrocarbon
production
operations at suitable offshore locations.
[0024] In the example illustrated, numerous wellheads 26 are associated
with the
platform 22, and the oriented casings 28 corresponding with each wellhead 26
are
oriented to avoid interference with other boreholes drilled into the subsea
formation and
lined with borehole casings. Each group, e.g. pair, of oriented casings 28
associated with
a corresponding wellhead 26 is oriented with a specific exit angle and
azimuthal
orientation so as to avoid interference with the boreholes and borehole
casings from other
oriented casings 28 associated with other corresponding wellheads 26. The
number and
arrangement of platform slots 24 in a given platform 22 may vary depending on
the
application and may comprise, for example, 10 to 30 slots. In the specific
example
illustrated, platform 22 comprises 20 slots which each have a dual wellhead to
create a
multilateral well having, for example, 40 lateral boreholes. It should be
noted, however,
that the system and methodology described herein for orienting boreholes can
be used
both with multiple wellheads or with a single grouping of oriented casings
associated
with a single wellhead 26.
[0025] Referring generally to Figure 2, an example of a structure 30 for
orienting
boreholes 32 of lateral wells is illustrated. In this example, a conductor
tube 34 extends
down from platform 22 and into a hole 36 which may be drilled or otherwise
formed in a
seabed 38. In many applications, the conductor tube 34 is positioned in the
hole 36 in a
generally vertical orientation and extends upwardly to platform 22. A
plurality of the
oriented casings 28 is arranged within the conductor tube 34 such that the
oriented
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casings 28 are positioned in a desired orientation. For example, the oriented
casings 28
may be arranged so that lower, outlet ends 40 of the oriented casings 28 have
specific exit
angles and a desired azimuthal orientation, as illustrated in Figure 3. The
specific exit
angles and azimuthal orientations are predetermined so that the boreholes 32
formed
beneath the oriented casings 28 are properly oriented to avoid interference
with other
boreholes of the multilateral well 20.
[0026] Depending on the application, a variety of orientation mechanisms
42 may
be employed to orient the casings 28 and the corresponding outlet ends 40 with
the
specific, desired exit angles and azimuthal orientations. For example, various
orientation
mechanisms 42 may be constructed to secure the oriented casings 28 in a
desired
relationship and to affix the oriented casings 28 within the surrounding
conductor tube 34
at the appropriate orientation. As discussed in greater detail below, the
plurality of
oriented casings 28 may be assembled in sequentially oriented and coupled
modules to
ensure that the oriented casings 28 and their corresponding lower outlet ends
40 are
properly oriented for each wellhead 26.
[0027] Once the oriented casings 28 and the corresponding conductor tube
34 are
properly oriented and placed in hole 36, boreholes 32 may be drilled. The
drilling of
boreholes 32 is at least initiated along a desired trajectory due to the exit
angle and
azimuthal orientation of the oriented casings 28 through which the drill
string is routed.
After drilling the boreholes 32, appropriate borehole casings 44 may be
delivered down
through oriented casings 28 and disposed in the corresponding boreholes 32.
The
borehole casings 44 may be cemented in place within their corresponding
boreholes 32.
[0028] Referring generally to Figure 4, a specific embodiment is
illustrated in
which the conductor tube 34 extends down into hole 36 from a well bay 46 of
platform
22. In this example, the conductor tube 34 is oriented generally vertically
between the
well bay 46 and the seabed 38. Additionally, this example illustrates the
plurality of
oriented casings 28 as comprising two oriented casings 28 positioned within
conductor
tube 34 and connected with wellhead 26 in the form of a dual wellhead.
Depending on
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the application, the lengths, diameters, and configurations of the various
system
components may vary. In a specific example using standard pipe diameters, the
hole 36
may be drilled as a 42 inch hole and the conductor tube 34 may comprise a 36
inch
diameter conductor pipe. In this example, the oriented casings 28 may comprise
16 inch
diameter casings and the borehole casings may comprise 13 and 3/8 inch
borehole
casings. However, other applications may use conductor tubes ranging from 20
to 50
inches in diameter with oriented casings ranging from 6 to 24 inches in
diameter that
cooperate with borehole casings from 4 to 22 inches in diameter. Additionally,
it should
be noted that many other diameters and sizes may be used depending on the
parameters
of a given application.
[0029] In some applications, the oriented casings 28 may be assembled
via
modules 48 which are sequentially aligned to position the oriented casings 28
so as to
extend along a desired orientation and to provide the desired exit angle and
azimuthal
orientation. An example of module 48 is illustrated in Figures 5-7 and
comprises a pair
of the oriented casings 28 positioned in the surrounding conductor tube 34.
Each module
48 may comprise a section of the conductor tube 34 with corresponding sections
of the
oriented casings 28 such that the sections of conductor tube 34 and
corresponding
sections of oriented casings 28 are stacked or coupled together in a specific
sequence that
provides the desired orientation of the internal oriented casings 28. However,
the
modules 48 also may be formed as sections of oriented casings 28 which are
stacked
within a corresponding conductor tube 34. Additionally, the modules 48 may be
formed
as sections of oriented casings 28 located in corresponding tubing sections
which are then
positioned and oriented within the surrounding conductor tube 34. Other
configurations
of modules 48 also may be used to provide the desired orientation of oriented
casings 28
for a given application.
[0030] In the example illustrated, each module 48 comprises sections of
the
oriented casings 28 held within a corresponding section of the conductor tube
34 at a
desired location with a plurality of plates or centralizers 50. The plates or
centralizers 50
may be welded or otherwise connected along an interior of the conductor tube
34 so as to
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provide the desired orientation of casings 28 for a given module 48. The
sequential
modules 48 may be connected together by welding, friction fits, sealed
insertion fits,
threaded couplers, and/or by other suitable fasteners and/or fastening
techniques.
Sequential modules 48 are oriented with respect to each other via suitable
orientation
features 52 which, in some applications, are coupled with the centralizers 50
located at
the longitudinal ends of the module 48. Each module 48 also may be marked with
an
identifier 54, such as a number or other indicator, which ensures that the
appropriate
module 48 is joined with the appropriate next sequential module 48 so as to
ensure the
desired orientation of oriented casings 28 along the entire conductor tube 34.
[0031] As further illustrated in Figures 8 and 9, an example of
orientation features
52 comprises an orientation pin 56 (see Figure 8) and a corresponding
orientation
opening or hole 58 (see Figure 9). In this example, the orientation pin 56
extends from
one of the centralizers 50 located at a longitudinal end of one module 48 and
is received
by a corresponding orientation hole 58 located at a corresponding longitudinal
end of the
next sequential module 48. The orientation pin 56 and orientation hole 58
ensure that the
oriented casings 28 of sequential modules 48 are properly aligned once the
orientation
pin 56 is inserted into the corresponding orientation hole 58. As further
illustrated, the
centralizers 50 also may be constructed with openings 60 sized for receipt of
oriented
casings 28.
[0032] In some applications, the sequential modules 48 are constructed
to
gradually rotate the orientation of the plurality, e.g. pair, of oriented
casings 28 along the
conductor tube 34. This gradual rotation of the orientation is illustrated
schematically in
Figure 10 which shows the differing angular positions of the pin 56 and
openings 60 from
one module 48 to the next. The overall alignment of oriented casings 28 and
the desired
exit angle and azimuthal orientation at lower outlet ends 40 may be achieved
by coupling
the appropriate modules 48 according to their indicators 54.
[0033] Referring generally to Figures 11 and 12, an embodiment of the
conductor
tube 34 and internal oriented casings 28 is illustrated. In this embodiment,
sequential
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modules 48 are coupled together sequentially as illustrated in Figure 13.
Additionally,
the sequential modules 48 may be oriented via orientation pins 56 and
corresponding
orientation holes 58 located at the ends of each module 48 to ensure proper
engagement
of sequential modules once they are coupled together according to the
identifiers 54. In
this example, a check valve 62 is located in each oriented casing 28. For
example, an
individual check valve 62 may be positioned proximate a lower end, e.g.
proximate lower
outlet end 40, of each oriented casing 28. The check valves 62 are oriented to
allow
down flow of fluid into the hole 36, as illustrated by arrows 64, while
restricting or
blocking up flow of fluid into the oriented casings 28. The check valves 62
are useful in
cementing operations, e.g. cementing of hole 36, while blocking unwanted
upflow of
cement into the oriented casings 28. It should be noted that in certain
applications a
check valve 62 may be omitted from one or more of the oriented casings 28. For
example, one of the oriented casings 28 may be used for conducting the outward
flow of
cement as indicated by arrows 64 without having a check valve 62. However, the
other
oriented casing or casings 28 comprise the check valve(s) 62 to restrict or
block the up
flow of cement into the other oriented casing or casings.
[0034] In an operational example, the hole 36 is initially drilled into
the seabed 38
generally below the region of platform 22. The conductor tube 34 is then
dropped down
into the hole 36. A plurality of oriented casings 28, e.g. two oriented
casings 28, is
arranged and oriented within the conductor tube 34 (see Figure 11). As
discussed above,
the pair of oriented casings 28 may be properly oriented within the
corresponding
conductor tube 34 during assembly of the conductor tube 34 and the internal
oriented
casings 28 via sequential modules 48 (see Figure 13). However, in other
applications, the
modules 48 may comprise internal modules formed separately from the conductor
tube
34 and comprising sections of oriented casings 28 in combination with
centralizers 50
and/or a surrounding support tube. In this latter embodiment, the internal
modules 48
would be assembled and moved down through the conductor tube 34. In some
applications, the modules 48 are formed with sections of conductor tube 34 and
corresponding centralizers 50, and the oriented casings 28 are inserted down
through
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openings 60 into conductor tube 34 in a manner similar to inserting straws
down into a
tube.
[0035] After proper placement/arrangement of the oriented casings 28
within
conductor tube 34, a cementing operation may be performed by cementing down
through
one of the oriented casings 28. The cement flows down through the check valve
62 (see
Figures 11 and 12) of the oriented casing 28 which is used for conducting the
flow of
cement (or down through an open, oriented casing 28 if no check valve 62 is
employed in
the oriented casing 28 used to deliver the cement). However, the check valves
62
collectively block up flow of the cement into the other oriented casing or
casings 28. The
cement flows down into hole 36 and fills the hole 36 up toward, to, or past
the lower end
of the conductor tube 34 depending on the specifics of a given application.
[0036] Once this initial cementing operation is completed, the boreholes
32 may
be drilled. The drilling of each borehole 32 is initiated along a specific
predetermined
exit angle and azimuthal orientation due to the orientation of the
corresponding oriented
casing 28. As described above, the oriented casings 28 in each conductor tube
34 are
properly oriented to provide the specific, predetermined exit angle and
azimuthal
orientation. The exit angles and azimuthal orientations are enabled by the
appropriate
construction and orientation of sections of the oriented casings 28 via
assembly of the
proper sequence of modules 48 (or by using other suitable orientation
mechanisms 42).
If check valves 62 are employed, the check valves 62 may be removed by
drilling
through the check valves or by other suitable removal techniques. Following
drilling of
the boreholes 32, borehole casings 44 are placed along the boreholes 32 and
again are
routed out of the corresponding oriented casings 28 with the appropriate,
predetermined
exit angle and azimuthal orientation. After the borehole casings 44 are
properly placed in
the corresponding boreholes 32, the borehole casings 44 may be cemented in
place by,
for example, performing a cementing operation down through one or more of the
oriented
casings 28.
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[0037] If more than one conductor tube 34 is positioned, the oriented
casings 28
in each conductor tube 34 may be oriented collectively to provide unique exit
angles and
azimuthal orientations with respect to other oriented casings 28 associated
with other
conductor tubes 34. For example, certain applications employ platform 22 with
multiple
platform slots 24, as illustrated in Figure 1, to enable construction of a
multilateral well.
Each platform slot 24 is associated with the corresponding wellhead 26, e.g. a
corresponding dual wellhead, having conductor tube 34 and internal oriented
casings 28
extending below the corresponding wellhead 26 to the appropriate hole 36
formed in
seabed 38.
[0038] The internal oriented casings 28 associated with each platform
slot 24 and
corresponding wellhead 26 are uniquely oriented with respect to exit angle and
azimuthal
orientation with respect to the numerous other internal oriented casings 28.
This enables
the drilling of the multiple associated boreholes 32 and placement of the
multiple
corresponding borehole casings 44 in a non-interfering pattern, as illustrated
in Figure 14.
[0039] As described herein, the overall multilateral well system 20 may
comprise
many types of systems and components for use in a variety of subterranean well
applications. For example, various types of platforms 22, platform slots 24,
and
wellheads 26 may be employed. The number and arrangement of platform slots 24
and
wellheads 26 also may change from one application to another. Additionally,
the
materials and configurations of the various conductor tubes 34, oriented
casings 28,
borehole casings 44, orienting mechanisms 42/52, and/or other components may
be
adjusted according to the parameters of a given application.
[0040] Additionally, the processes employed may be adjusted according to
the
environment and/or parameters of a given well application. For example,
various
techniques may be used for drilling hole 36 and boreholes 32. Similarly, a
variety of
equipment and techniques may be employed for performing the cementing
operations
both within hole 36 and along boreholes 32. A number of other and/or
additional
components may be used to facilitate drilling, cementing, testing, and/or
production
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operations. Many types of configurations also may be used for modules 48 to
facilitate
assembly of specific sequential modules which ensure that internal oriented
casings 28
provide the proper predetermined exit angle and azimuthal orientation so as to
enable
formation of multiple non-interfering boreholes and associated borehole
casings.
[0041] Although
a few embodiments of the disclosure have been described in
detail above, those of ordinary skill in the art will readily appreciate that
many
modifications are possible without materially departing from the teachings of
this
disclosure. Accordingly, such modifications are intended to be included within
the scope
of this disclosure as defined in the claims.
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