U.S. patent application number 14/910844 was filed with the patent office on 2016-07-21 for system and methodology for running casing strings through a conductor tube.
The applicant listed for this patent is Schlumberger Technology Corporation. Invention is credited to Stephen BILLEAUD, Malcolm PERSCHKE, Benny POEDJONO.
Application Number | 20160208586 14/910844 |
Document ID | / |
Family ID | 52461927 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160208586 |
Kind Code |
A1 |
PERSCHKE; Malcolm ; et
al. |
July 21, 2016 |
SYSTEM AND METHODOLOGY FOR RUNNING CASING STRINGS THROUGH A
CONDUCTOR TUBE
Abstract
A technique facilitates miming of casing strings in a
multilateral well. 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 have 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.
Inventors: |
PERSCHKE; Malcolm; (Spring,
TX) ; POEDJONO; Benny; (Sugar Land, TX) ;
BILLEAUD; Stephen; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schlumberger Technology Corporation |
Sugar Land |
TX |
US |
|
|
Family ID: |
52461927 |
Appl. No.: |
14/910844 |
Filed: |
August 7, 2014 |
PCT Filed: |
August 7, 2014 |
PCT NO: |
PCT/US2014/050093 |
371 Date: |
February 8, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61863163 |
Aug 7, 2013 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/10 20130101;
E21B 33/14 20130101; E21B 7/061 20130101; E21B 17/18 20130101; E21B
34/06 20130101; E21B 41/0035 20130101 |
International
Class: |
E21B 43/10 20060101
E21B043/10; E21B 34/06 20060101 E21B034/06; E21B 17/18 20060101
E21B017/18; E21B 33/14 20060101 E21B033/14 |
Claims
1. A method for orienting casing strings, comprising: drilling a
hole in a seabed; positioning a conductor tube into the hole;
arranging a plurality of oriented casings in the conductor tube via
modules which are aligned to position the oriented casings so as to
extend in a desired orientation; operating a drill string through
each orienting casing to form a borehole extending beneath the
conductor tube along the desired orientation; and placing casing
along each borehole.
2. The method as recited in claim 1, further comprising performing
a cementing operation through an oriented casing of the plurality
of oriented casings in the conductor tube prior to forming the
boreholes beneath the conductor tube.
3. The method as recited in claim 2, wherein cementing comprises
pumping cement down one oriented casing of the plurality of
oriented casings.
4. The method as recited in claim 3, further comprising providing a
check valve in each oriented casing to block upflow of cement into
the plurality of oriented casings during cementing.
5. The method as recited in claim 1, wherein deploying the
plurality of oriented casings comprises deploying two oriented
casings in the conductor tube.
6. The method as recited in claim 1, wherein deploying the two
oriented casings comprises deploying the two oriented casings so as
to extend into the conductor tube from a dual wellhead.
7. The method as recited in claim 1, wherein deploying the two
oriented casings comprises deploying the two oriented casings so as
to extend into the conductor tube from a well bay.
8. The method as recited in claim 6, further comprising locating a
plurality of the dual wellheads on a platform; and using pairs of
the oriented casings for each wellhead so as to provide unique
orientations relative to the orientations of other pairs of
oriented casings.
9. The method as recited in claim 1, further comprising aligning
the modules via alignment pins and corresponding alignment openings
in adjacent modules.
10. A system for orienting casing strings, comprising: a platform
cooperating with a plurality of conductor tubes extending beneath a
platform to a seabed location, each conductor tube having a
plurality of oriented casings which are arranged to provide a
desired exit angle and azimuthal orientation, the plurality of
oriented casings in the plurality of conductor tubes being arranged
to facilitate formation of boreholes extending from the pluralities
of oriented casings; and a plurality of borehole casings placed in
the boreholes so each borehole casing extends from a corresponding
oriented casing of the pluralities of oriented casings without
interference from other boreholes or borehole casings.
11. The system as recited in claim 10, wherein the plurality of
oriented casings in each conductor tube comprises two oriented
casings.
12. The system as recited in claim 10, wherein the plurality of
oriented casings in each conductor tube comprises check valves to
facilitate cementing operations.
13. The system as recited in claim 10, wherein the borehole casings
are cemented in the corresponding boreholes.
14. The system as recited in claim 10, wherein the plurality of
oriented casings is constructed via an assembly of sequential,
oriented modules.
15. A method, comprising: placing a plurality of conductor tubes
into a seabed in conjunction with a platform; arranging a plurality
of oriented casings in each conductor tube; using the orientation
of each oriented casing to direct a corresponding drilling of a
borehole and placement of a borehole casing in the borehole without
interfering with other boreholes and borehole casings associated
with other oriented casings.
16. The method as recited in claim 15, further comprising
assembling the plurality of oriented casings as a series of modules
arranged to establish the desired exit angle and azimuthal
orientation for each plurality of oriented casings.
17. The method as recited in claim 15, further comprising
performing a cementing operation through at least one of the
oriented casings.
18. The method as recited in claim 17, further comprising placing
check valves at lower ends of the oriented casings.
19. The method as recited in claim 15, further comprising cementing
each borehole casing in its corresponding borehole.
20. The method as recited in claim 16, further comprising using
alignment features to couple together a desired sequence of modules
containing sections of the oriented casings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present document is based on and claims priority to U.S.
Provisional Application Ser. No. 61/863,163, filed Aug. 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.
[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] FIG. 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] FIG. 2 is a schematic illustration of an example of a
conductor tube having internal oriented casings, according to an
embodiment of the disclosure;
[0008] FIG. 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] FIG. 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] FIG. 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;
[0011] FIG. 6 is a cross-sectional illustration of the module
illustrated in FIG. 5, according to an embodiment of the
disclosure;
[0012] FIG. 7 is a cross-sectional view of a module having dual
oriented casings, according to an embodiment of the disclosure;
[0013] FIG. 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] FIG. 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] FIG. 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] FIG. 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] FIG. 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] FIG. 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] FIG. 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.
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.
[0023] Referring generally to FIG. 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 FIG. 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 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 FIG. 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 FIG. 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 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 FIGS. 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 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 FIGS. 8 and 9, an example of
orientation features 52 comprises an orientation pin 56 (see FIG.
8) and a corresponding orientation opening or hole 58 (see FIG. 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
FIG. 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 FIGS. 11 and 12, an embodiment of the
conductor tube 34 and internal oriented casings 28 is illustrated.
In this embodiment, sequential modules 48 are coupled together
sequentially as illustrated in FIG. 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 FIG. 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 FIG. 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 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 FIGS. 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.
[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 FIG. 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 FIG. 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
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.
* * * * *