U.S. patent application number 12/502039 was filed with the patent office on 2009-11-05 for method and apparatus for a downhole excavation in a wellbore.
Invention is credited to Bruce A. Dale, John W. Mohr.
Application Number | 20090272547 12/502039 |
Document ID | / |
Family ID | 32990773 |
Filed Date | 2009-11-05 |
United States Patent
Application |
20090272547 |
Kind Code |
A1 |
Dale; Bruce A. ; et
al. |
November 5, 2009 |
METHOD AND APPARATUS FOR A DOWNHOLE EXCAVATION IN A WELLBORE
Abstract
The method and apparatus can create excavation cavities suitable
for drilling multilateral wellbores through the excavation using a
kick-off. One embodiment of the method comprises isolating a
wellbore at a determined location, excavating a downhole cavity in
a wellbore above the determined location, and removing the
apparatus for isolating the wellbore and the apparatus for
excavating the downhole cavity from the wellbore to provide full
access to the wellbore and the excavation cavity.
Inventors: |
Dale; Bruce A.; (Sugar Land,
TX) ; Mohr; John W.; (Surrey Hills, AU) |
Correspondence
Address: |
Brent R. Knight;ExxonMobil Upstream Research Company
CORP-URC-SW348, P. O. Box 2189
Houston
TX
77252-2189
US
|
Family ID: |
32990773 |
Appl. No.: |
12/502039 |
Filed: |
July 13, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10547439 |
Aug 25, 2006 |
7575050 |
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PCT/US04/01744 |
Jan 22, 2004 |
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12502039 |
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60453440 |
Mar 10, 2003 |
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Current U.S.
Class: |
166/387 ;
175/263; 175/61 |
Current CPC
Class: |
E21B 7/061 20130101 |
Class at
Publication: |
166/387 ; 175/61;
175/263 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 7/06 20060101 E21B007/06 |
Claims
1) An apparatus for excavating in a wellbore comprising, (a) means
for isolating a wellbore at a determined location; (b) means for
excavating a downhole cavity around the entire circumference of a
portion of the wellbore; wherein the means for excavating is
adapted to provide a downhole cavity having at least one
configuration selected from the group comprising: a cavity having
radial clearance to enable lateral kick-off without concrete plugs;
a cavity sized to accommodate kick-off of multiple laterals from
the cavity; and (c) means for removing the means for isolating the
wellbore and means for excavating a downhole cavity in a wellbore
thereby providing full access to the wellbore and the excavated
cavity.
2) The apparatus of claim 1 further comprising means for drilling a
lateral bore through the excavated cavity.
3) The apparatus of claim 1 wherein the downhole cavity is
substantially concentric with respect to the wellbore.
4) The apparatus of claim 1 wherein the means for excavating the
downhole cavity removes a section of casing from the wellbore.
5) The apparatus of claim 1 further comprising drilling at least
two lateral bores through the excavated cavity.
6) A method for excavating a wellbore comprising, (a) providing
means to isolate a wellbore; (b) isolating a wellbore at a
determined location; (c) providing means to excavate a downhole
cavity in the wellbore; and (d) excavating a downhole cavity around
the entire circumference of a section of the wellbore.
7) The method of claim 6 further comprising removing the means for
excavating the downhole cavity from the wellbore and removing the
means for isolating the wellbore thereby providing full access to
the wellbore and the excavated cavity.
8) The method of claim 6 further comprising drilling a lateral bore
through the excavated cavity.
9) The method of claim 6 wherein the downhole cavity is
substantially concentric with respect to the wellbore.
10) The method of claim 6 wherein the means for excavating the
downhole cavity removes a section of casing from the wellbore.
11) The method of claim 7 further comprising drilling a plurality
of lateral bores through the excavated cavity.
12) A method for excavating a wellbore comprising, (a) installing a
packer in a wellbore at a desired orientation; (b) attaching a
drillpipe stinger on top of the packer, the drillpipe stinger
comprising a tapered top adapted to attach an overshot section
milling on top of the drillpipe stinger and a hollow ported-stub,
means for the drillpipe stinger ports to direct flow of drilling
fluids to the annulus between the drillstring and casing wherein
the circulation of drilling fluids removes drill cuttings; (c)
attaching an overshot section milling assembly to the tapered top
on the drillpipe stinger; (d) initiating the drillstring rotation
to extend the section-mill retractable arm to cut a cavity in the
casing; and (e) initiating pumping operations to lift the cutting
debris out of the well.
13) The method of claim 12 further comprising removing the overshot
section milling assembly from the wellbore.
14) The method of claim 13 further comprising removing the
drillpipe stinger and packer thereby providing full access to the
wellbore and the excavated cavity.
15) The method of claim 12 wherein the tapered drillpipe stinger
top is adapted to attach an overshot whipstock assembly and further
comprising; (a) providing an overshot whipstock assembly on a
drillstring and attaching the overshot whipstock assembly on the
tapered top of the drillpipe stinger; (b) releasing the drillpipe
stinger from the overshot whipstock assembly and pulling the
drillstring out of the wellbore; and (c) running a drilling
assembly to drill a lateral bore.
16) The method of claim 15 further comprising removing the overshot
whipstock assembly, drillpipe stinger and packer, thereby providing
full access to the wellbore and the cavity.
17) The method of claim 15 further comprising cementing a lateral
liner in the lateral bore.
18) The method of claim 17 further comprising a washover procedure
wherein the washover procedure retrieves the liner stub protruding
from the lateral bore, the overshot whipstock assembly and the
drillpipe stinger assembly.
19) A multilateral wellbore comprising a lateral bore drilled
according to the method of claim 15.
Description
[0001] This application is a continuation application under 35
U.S.C. .sctn. 120 of pending U.S. patent application Ser. No.
10/547,439, entitled "A METHOD AND APPARATUS FOR A DOWNHOLE
EXCAVATION IN A WELLBORE", filed Aug. 26, 2005, which is the
national stage application under 35 U.S.C. .sctn.371 of
International Application No. PCT/US2004/01744, of the same title,
filed Jan. 22, 2004, which claims the benefit of U.S. Provisional
Patent Application No. 60/453,440, filed Mar. 10, 2003. Each of
these applications is hereby incorporated by reference in its
entirety for all purposes.
FIELD OF THE INVENTION
[0002] This invention relates to downhole excavations in a
wellbore. More particularly, this invention relates to a method and
apparatus for downhole excavations in a wellbore suitable for
creating a kick-off for a multi-lateral well.
BACKGROUND
[0003] In order to enhance the recovery of subterranean fluids,
such as oil and gas, it is sometimes desirable to orient the
direction of the wellbore or borehole. In an oil producing
formation or strata which has limited vertical depth and relatively
greater horizontal extent with respect to the surface of the earth,
a wellbore which extends horizontally through the oil producing
formation may be more productive than one extending vertically. In
order to create an inclined, highly deviated or horizontal
borehole, it is necessary to steer the drilling bit at the end of
the drill string from a generally vertical orientation to a lateral
or horizontal orientation.
[0004] In steering a drill bit and drill string from a vertical
orientation to a horizontal or other non-vertical orientation, it
is necessary to deflect or side-track the drill bit from the
generally vertical borehole to a drilling direction inclined to the
wall of the borehole. This initial step is also known as "kicking
off" or a kick-off of the drill bit and drill string. It is typical
to first drill a vertical wellbore and then attempt to deflect the
drill bit and drill string by some means thereby causing it to
drill through the wall of the existing wellbore.
[0005] When drilling a deviated wellbore from a cased well, a
section of the casing must first be cut and removed. Once the
casing is removed, an opening is provided for the drill bit to pass
through the casing into the cement surrounding the casing and then
through the formation.
[0006] The development of techniques for drilling relatively high
angle deviated wells from a generally vertical wellbore has
provided several advantages in recovering oil and gas from
subterranean formations. One or more deviated or generally
horizontal wellbores may be drilled from single generally vertical
wellbore to provide wellbores which: (a) reach irregular reservoirs
without additional wells being drilled from the surface, (b) limit
the invasion of unwanted formation fluids, (c) penetrate natural
vertical fractures (d) improve production from various types of
formations or reservoirs and (e) provide new conduits for
hydrocarbons to flow to the surface.
[0007] The creation of multi-lateral wells from either new or
existing wellbores usually involves some sort of sidetracking
process that utilizes whipstocks and/or section mills to create an
exit point in the casing to allow a drilling assembly to "kick-off"
from the main wellbore. During such procedures, communication is
often severed with the main wellbore below the point of kick-off,
thus eliminating the use of the lower portion of the main wellbore
for the continued production of hydrocarbons. Also, these
multi-lateral construction procedures result in wellbore diameters
that are the same size or smaller than the existing wellbore.
[0008] For multi-lateral well drilling, section mills are generally
not used since they result in complete severing of the main
wellbore, which makes re-locating the main wellbore below the
casing exit point difficult, if not impossible. Nonetheless,
section mills offer the potential to improve multi-lateral well
juncture construction due to the greater available space for
creating a sealed hydraulic juncture while maintaining full-bore
accessibility.
[0009] Downhole excavation would facilitate construction of
multi-lateral wells in several ways. First, downhole excavation
would allow creation of a large downhole cavity while maintaining
access to the existing wellbore below the excavation point. Second,
downhole excavation would provide an alternative method for
"kicking off" the lateral from the main well bore in multi-lateral
well drilling. Third, downhole excavation would provide a large
area to facilitate construction of a hydraulically sealed juncture
that maintains full-bore accessibility. Fourth, downhole excavation
would provide a large excavated location where multiple laterals
could be kicked-off from the same location in the parent casing
bore.
[0010] A significant amount of technology has been developed in the
area of multi-lateral wells and section milling to enlarge
boreholes. However, no examples are available demonstrating the use
of section mills to create large downhole cavities for
multi-lateral well construction and permit access to parent casing
bore below the kick-off.
[0011] Accordingly, there is a need for a method and apparatus to
provide an excavation suitable for a multi-lateral well while
maintaining full bore access below the excavation. This invention
satisfies that need.
SUMMARY
[0012] An apparatus for excavating in a wellbore is disclosed. The
apparatus comprises means for isolating a wellbore at a determined
location, means for excavating a downhole cavity in a wellbore, and
means for removing the means for isolating the wellbore and means
to excavate the downhole cavity in the wellbore thereby providing
full access to the wellbore and the excavation.
[0013] A second apparatus embodiment for excavating a wellbore is
disclosed. This embodiment comprises a whipstock packer capable of
isolating the wellbore below the whipstock packer and a drillpipe
stringer above the whipstock packer comprising, a hollow washover
ported-stub, means for the ports on the drillpipe stinger to direct
drilling fluid flow to the annulus between the drillstring and
casing, and a tapered top capable of receiving an overshot section
milling assembly.
[0014] A method for excavating in a wellbore is disclosed. This
embodiment comprises isolating a wellbore at a determined location,
providing means for excavating a downhole cavity in a wellbore,
excavating a downhole cavity in a wellbore above the determined
location, and removing the means for isolating the wellbore and
means for excavating the downhole cavity from the wellbore to
provide full access to the wellbore and the excavation cavity.
[0015] A second method embodiment for excavating in a wellbore is
disclosed. This embodiment comprises: (a) providing a whipstock
packer in a wellbore at a desired orientation, (b) attaching a
drillpipe stinger on top of the whipstock packer, the drillpipe
stinger comprising a tapered top capable of attaching to an
overshot section milling assembly on top of the drillpipe stinger
and a hollow washover ported-stub, means for the drillpipe stinger
ports to direct flow of drilling fluids to the annulus between the
drillstring and casing wherein the circulation of drilling fluids
removes drill cuttings, (c) attaching an overshot section milling
assembly to the tapered top on the drillpipe stinger, (d)
initiating the drillstring rotation to extend the section-mill
retractable arm to cut a cavity in the casing, (e) initiating
pumping operations to lift the cutting debris out of the well, (f)
repeating steps (d) and (e) until the cavity has the desired
size.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an illustration of a drillpipe stinger;
[0017] FIG. 2 is an illustration of an overshot section milling
assembly;
[0018] FIG. 3(a) is a side view illustration of an external
overshot whipstock assembly;
[0019] FIG. 3(b) is a top view illustration of an external overshot
whipstock assembly;
[0020] FIG. 4(a) is a side view illustration of an internal
overshot whipstock assembly;
[0021] FIG. 4(b) is a top view illustration of an internal overshot
whipstock assembly;
[0022] FIG. 5 is a flowchart illustration of a method to excavate a
wellbore;
[0023] FIG. 6 is a flowchart illustration of a second embodiment of
the method to excavate a wellbore;
[0024] FIG. 7 is a flowchart illustration of a third embodiment of
the method to perform lateral drilling through a excavated
cavity;
[0025] FIG. 8 is an illustration of a whipstock packer in a
wellbore for isolating the section of the wellbore below the
whipstock packer;
[0026] FIG. 9 is an illustration of a wellbore with a drillpipe
stinger inserted into the whipstock packer and a section milling
assemble mated above the drillpipe stinger;
[0027] FIG. 10 is an illustration of the activation of the section
milling assembly of FIG. 9 to excavate a section-milled cavity;
[0028] FIG. 11 is an illustration of wellbore after the removal of
the section milling assembly after the excavation of the
section-milled cavity;
[0029] FIG. 12 is an illustration of an external whipstock mated on
top of the drillpipe stinger after the removal of the section
milling assembly;
[0030] FIG. 13 is an illustration of a cased wellbore after a
lateral bore has been drilled through the excavated cavity and the
whipstock packer, drillpipe stinger and whipstock assembly has been
removed.
DETAILED DESCRIPTION
[0031] In the following detailed description and example, the
invention will be described in connection with its preferred
embodiments. However, to the extent that the following description
is specific to a particular embodiment or a particular use of the
invention, this is intended to be illustrative only. Accordingly,
the invention is not limited to the specific embodiments described
below, but rather, the invention includes all alternatives,
modifications, and equivalents falling within the true scope of the
appended claims.
[0032] This invention provides a method and apparatus for
excavating a wellbore. The excavations are suitable for creating
multilateral wells through kick-offs. The apparatus requires means
for isolating a wellbore at a determined location and means for
excavating a downhole cavity in the wellbore. One method embodiment
comprises isolating the wellbore, then excavating a cavity and
finally removing the means for isolating and excavating the
wellbore from the wellbore to provide full access to the wellbore
and excavation cavity. This method embodiment can create large
cavities having a diameter on the order of two to ten times the
diameter of the original borehole.
[0033] Preferred devices to provide the means for isolating the
wellbore at a determined location and for cutting a large downhole
cavity include: whipstock packer, drillpipe stinger, overshot
section-milling assembly, and an overshot whipstock assembly for
lateral drilling. Persons skilled in the art may recognize other
devices that are equivalent and can accomplish the same tasks.
Therefore, the list of devices are not intended to be limiting but
rather to provide specific examples of equipment than can be
utilized to practice this invention.
[0034] FIG. 1 shows a drillpipe stinger 1. This tool consists of a
conventional seal area and a latch mechanism 3 that engages and
anchors into a conventional whipstock packer (not shown) to
temporarily isolate at a determined depth the wellbore below the
whipstock packer. The drillpipe stinger includes a hollow
ported-stub 5, with length 8 approximately 5 to 10 meters. The
fluid ports 7 on the drillpipe stinger will divert flow of drilling
fluid to the annulus between the drillstring and casing to allow
for circulation of drilling fluid to remove drill cuttings. The top
of the drillpipe stinger has a tapered face 9 to facilitate the
receiving or mating of the overshot section milling assembly. In
addition, the tapered face 9 can be adapted to receive and run an
overshot whipstock assembly that would allow deflection of the
drilling assembly into a section-milled cavity.
[0035] While this patent specifically discusses the drillpipe
stinger assembly in order to maintain contact with the lower
wellbore, persons skilled in the art will recognize other methods
to maintain connectivity including cable or wireline guide ropes. A
variety of materials could be utilized to temporarily bridge the
gap between the existing upper and lower casing strings including
specialized pipe or tubing.
[0036] FIG. 2 shows an overshot section milling assembly 13. This
tool assembly is designed to fit over and latch to the drillpipe
stinger stub (not shown). After landing on the drillpipe stinger,
the overshot section milling assembly may be appropriately released
from the drillpipe stringer assembly to allow axial and rotational
movement to facilitate casing cutting and formation underreaming
operations. The retractable cutting arms 15 on the tool assembly
are activated by pump pressure and drillstring rotation and will be
capable of removing existing casing as well as enlarging the
borehole. Appropriate wiper seals 17 are included in the overshot
bore to achieve a low-pressure seal barrier to exclude drill solids
and milling debris. Typically, the top of the overshot section
milling assembly provides a drillpipe tool joint 19 (box
connection) to removedly connect (or attach with the ability to
disconnect) the overshot section milling assembly to a drillpipe.
In FIG. 2, the entire height 28 of the overshot section milling
assembly 13 is approximately 5 to 10 meters.
[0037] While this patent specifically discusses the use of a
mechanical cutting tool (such as an overshot section milling
assembly) persons skilled in the art would recognize other methods
that could be utilized to create a large downhole cavity. These
methods include but are not limited to chemical cutting, water-jet
cutting, laser cutting, explosive cutting, and shaped-charge
cutting.
[0038] FIG. 3(a) shows an illustration of an overshot whipstock
assembly 31. As illustrated in FIG. 3(a), this tool assembly is
designed to fit over and latch to the drillpipe stinger stub (not
shown) in a manner similar to the overshot section-milling
assembly. The internal bore 30 of this tool assembly will mate with
the tapered surface of the drillpipe stinger assembly (not shown)
and be offset to one side of the wellbore casing. The offset nature
of the whipstock allows the back 33 of the whipface assembly to be
supported against the existing borehole casing and provides
adequate clearance for the drilling assembly to deflect off the
whipstock face 35 into the excavated section-milled cavity.
Whipface supports 37 may be added to the back 33 of the overshot
whipstock assembly 31 to provide additional support against the
borehole casing. Low-pressure wiper seals 34 can be aligned with
the fluid ports of the drillpipe stinger (not shown) to prevent
mixing of fluid below the whipstock packer with fluid above the
whipstock packer. In the FIG. 3(a) illustration, the entire height
46 of the overshot whipstock assembly 31 is approximately 5 to 10
meters.
[0039] FIG. 3(b) is a top view of the overshot whipstock assembly
31 in which the like elements to FIG. 3(a) have like numerals. FIG.
3(b) shows the tapered surface of the overshot whipstock assembly
whipface 35 to deflect the drilling assembly into the excavated
cavity.
[0040] Both internal and external overshot whipstock assemblies
could be utilized. FIGS. 3(a) and 3(b) shows an external whipstock
assembly. FIGS. 4(a) and 4(b) shows an internal whipstock assembly
31 in which the like elements to FIG. 3(a) have like numerals. The
internal overshot whipstock assembly whipface 35 is covered by a
top 39 comprising a lateral bore 38 through which the drilling
assembly can be inserted through the top 39 of the overshot
whipstock assembly 31. When inserted, the drilling assembly would
deflect off the whipface 35 through the lateral bore 38 into the
side of the wellbore to create a kick-off through the excavated
cavity. Persons skilled in the art can optimize the size and shape
of the overshot whipstock assembly based upon the actual lengths of
the drillpipe stinger assembly and the section-milled cavity. In
the FIG. 4(a) illustration, the entire height 46 of the overshot
section milling assembly 31 is approximately 5 to 10 meters.
[0041] The preferred use of this invention is specifically to
excavate a large downhole cavity for the creation of multi-lateral
wells. However, persons skilled in the art will recognize other
uses of an excavated cavity including downhole equipment storage
areas and construction zones for downhole structures or pieces of
equipment.
EXAMPLE
[0042] FIG. 5 is a flow chart of an embodiment for the method to
create an excavated cavity in a wellbore. As illustrated in FIG. 5,
the first step is to determine the location for excavating a
wellbore 51. The second step is to isolate the wellbore below the
location to be excavated 53. The third step is to create a downhole
cavity in a wellbore 55.
[0043] FIG. 6 is a flow chart of a second more detailed method
embodiment for excavating a cavity in a wellbore. It is envisioned
that the steps listed in FIG. 6 would be the preferred utilized
steps during the downhole excavation process, and the steps are
illustrated in FIGS. 8 to 13. Persons skilled in the art would
recognize that the order in which these procedures are performed
could be changed to accomplish various drilling and completion
objectives. Also, these procedures are applicable to wells at any
inclination ranging from vertical to horizontal wells and include
the provision for creating multiple casing exits at approximately
the same measured depth of the well.
[0044] Referring to FIG. 6, a conventional whipstock orienting
packer is first run in the well and can be set hydraulically or
using wireline to isolate the wellbore at a location in the
wellbore 61. As illustrated in FIG. 8, the whipstock packer 81 is
then is oriented along the casing wall 83 of the wellbore 87 to
facilitate subsequent operations. Also illustrated are seal stack
receptacles 85 designed to seal the whipstock packer against the
drillpipe stinger (not shown).
[0045] Referring to FIG. 6, a drillpipe stinger is next attached or
mated on top of a whipstock packer 62 and then an overshot section
milling assembly is attached to the top of the drillpipe stinger
63. FIG. 9 shows a drillpipe stinger 1 latched onto a whipstock
packer 81 with an overshot section milling assembly 13 mated above
the drillpipe stinger 1 inside the casing 83 of the wellbore
87.
[0046] Referring to FIG. 6, the next step is to initiate
drillstring rotation of the overshot section milling assembly to
excavate a cavity 64 with initiation of pumping operations to lift
the cutting debris out of the wellbore 65. FIG. 10 shows an
illustration of the apparatus of FIG. 9 after initiation of pumping
operations and drillstring rotation wherein like elements of FIG. 9
use the same number designations. The drillstring rotation extends
the section-mill retractable arms 15, to remove the casing wall 83
of the wellbore 87, cut the excavation cavity 107 and the pumping
operations lift the cutting debris out of the wellbore 87.
[0047] Referring to FIG. 6, a determination is made if the desired
cavity size has been achieved 66. If the desired cavity size has
been achieved, the excavation is complete 67. If the desired cavity
size has not been achieved repeat the previous two operations (64
and 65), as necessary, by initiating drillstring rotation to cut
the cavity 107.
[0048] Upon completion of cavity, the overshot section-milling
assembly is removed from the wellbore. FIG. 11 shows the whipstock
packer 81 inside the casing 83 of the wellbore 87 after the
overshot section milling assembly has been removed leaving the
whipstock packer 81, the drillpipe stinger 1 and the excavated
cavity 107.
[0049] At this point, one of several operations could be performed
to prepare the cavity for multi-lateral well juncture creation or
lateral drilling. FIG. 7 is a flow chart of an operation to perform
lateral drilling through the excavated cavity in the wellbore. FIG.
7 begins where FIG. 6 ended and requires that the overshot section
milling assembly be removed out of the wellbore 87. Next, the
overshot whipstock assembly is installed. One method to accomplish
installation of the overshot whipstock assembly is to run the
overshot whipstock assembly on a drillstring and stab it over the
drillpipe stinger 1. Next, the drillstring is released from the
overshot whipstock assembly and pulled out of the wellbore 73.
[0050] FIG. 12 shows an external overshot whipstock 31 mated on top
of the drillpipe stinger 1 in a wellbore 87 wherein like elements
from FIG. 3(a) are given like numerals. Referring to FIG. 7, the
drilling assembly is run and a lateral bore is drilled 74. In this
example, an external overshot whipstock was utilized. However, an
internal overshot whipstock could be utilized in the same manner as
the external overshot whipstock. The overshot whipstock could be
oriented at any angle within the excavated cavity, making it
possible to drill a lateral bore at any azimuth.
[0051] At the conclusion of lateral drilling procedures, a lateral
liner may be installed in the wellbore using conventional methods
75, including cementing the liner. After running the liner, the
liner stub protruding from the lateral, the overshot whipstock
assembly, and the drillpipe stinger assembly can all be retrieved
using conventional washover procedures 76. FIG. 13 shows the
wellbore 87 with the equipment removed leaving the central wellbore
130 with a lateral bore 133 and cement 135 around the exterior of
the casing 83 and the lateral bore 133. In the example given above
only one lateral bore was drilled. However, multiple lateral wells
could be drilled through the same excavation cavity or through
multiple excavation cavities.
* * * * *