CA 02642704 2011-06-09
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BACKGROUND OF THE INVENTION
Field of the Invention
100021 The present invention generally relates to a coiled tubing bottom hole
assembly used to create an acid tunnel in a wellbore formation such that the
tunnel is
substantially transverse to the wellbore. In particular, the present invention
relates to a coiled
tubing bottom hole assembly utilizing reversible knuckle joints to create a
tunnel
substantially transverse to the wellbore.
Description of the Related Art
100031 It has become common to stimulate a wellbore in an effort to increase
the
production of hydrocarbons. One method to stimulate an openhole wellbore is to
create an
acid tunnel that is substantially transverse to the wellbore. Acid tunneling,
also referred to as
chemically-enhanced drilling, is a process that uses a nozzle attached to a
bottom hole
assembly that is run into the wellbore with coiled tubing. Once the nozzle is
located at the
desired location within the wellbore, acid is pumped down the coiled tubing at
a high
pressure. The high pressure acid exits the nozzle and dissolves the formation
adjacent to the
nozzle creating a tunnel. The
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tunnel may be created at a specified location of the wellbore to extend beyond
a damaged or non-
producing portion of the well.
[0004) The bottom hole assembly preferably includes a knuckle joint used to
angle the
nozzle towards the side of the wellbore. The nozzle is typically located on
the end of a wand
connected to the knuckle joint. The diameter of the wellbore as well as the
geometric
configuration of the wand, nozzle, and bottom hole assembly dictate the angle
at which the
knuckle joint can be bent within the wellbore. The rigidity of the bottom hole
assembly causes
the bottom hole assembly to have a fixed radius of curvature. The radius of
curvature is dictated
by the length of the wand, the angle that the knuckle joint bends, and the
length of the assembly
from the knuckle joint to the coiled tubing connection. These dimensions
define a fixed radius
through which the bottom hole assembly may travel.
moos] It is generally desired to create an acid tunnel that is substantially
transverse to the
wellbore so that the tunnel extends beyond a damaged area of the wellbore. It
is also important
that the tunnel be substantially traverse because it may be desirable to
create multiple tunnels
within the wellbore. It is important that the attack angle of the nozzle be
sufficient to create a
tunnel that is substantially transverse to the wellbore. The knuckle of the
bottom hole assembly
needs to position the nozzle against the wellbore to ensure that the flow of
acid out of the nozzle
begins to form a tunnel. If the attack angle is too shallow, the high pressure
acid may simply
widen the bore of the wellbore rather than creating a tunnel transverse to the
wellbore. To
encourage the creation of a tunnel, the knuckle joint is often configured to
have a maximum bend
angle of approximately fifteen degrees away from the center of the bottom hole
assembly. A
fifteen degree bend angle typically allows knuckle to bend causing the nozzle
located on the end
of the wand to come into contact with the wellbore. Typically, the knuckle
will not be bent to its
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maximum angle until after the tunnel has begun to form. The angle required for
the knuckle to
contact the wellbore can be decreased by increasing the length of the wand.
However, increasing
the length of the wand also increases the chance that the wand may become cam
locked as it
traverse the wellbore and the tunnel entrance.
[0006] The coiled tubing is used to push the bottom hole assembly and increase
the
length of the acid tunnel. The bottom hole assembly is rigid and as discussed
above, the
geometry of the bottom hole assembly (i.e. the bend angle of the knuckle
joint, the length of the
wand, and the length from the coiled tubing to the knuckle joint) defines the
radius of curvature
or "build rate" of the bottom hole assembly. The build rate of the bottom hole
assembly
determines the "build angle" of the tunnel (i.e. how quickly the tunnel turns
so that it is
transverse to wellbore). Often it may be desirable to create multiple tunnels
in a single wellbore.
Thus, it is important to have a build rate in the tunnel that is as high as
practically possible, but
not so high that it exceeds the yield strength of the coiled tubing that is
connected to the
tunneling bottom hole assembly. For example, in a 6 inch diameter wellbore,
the current bottom
hole assembly for acid tunneling typically has a theoretical build rate of 300
degrees per 100 feet
of tunnel. This 'theoretical build rate exceeds the yield radius of curvature
of typical coiled
tubing. It would thus be beneficial to provide a bottom hole assembly that has
a lower build rate,
but that also may position the nozzle against the wellbore to ensure a tunnel
transverse to the
wellbore is created, but with a higher initial starting angle.
[0007] Current bottom hole assemblies have been use to create acid tunnels of
up to fifty
feet or more in length without damaging the coiled tubing. As discussed above,
the theoretical
build rate of the current bottom hole assembly exceeds the elastic limit of
coiled tubing. In
theory, if a fifty foot tunnel is created with the maximum build rate of the
current acid tunneling
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bottom hole assembly, then the coiled tubing would exceed yield and the force
required to push
the tunneling bottom hole assembly along the tunnel would exceed the buckling
strength of the
unsupported coiled tubing in the borehole. However, there have been instances
where a fifty foot
tunnel has been created without appreciable damage to the coiled tubing. One
explanation for
this occurrence is that the bottom hole assembly may have titled or twisted
out of its original
plane while creating the tunnel while at the same time creating an elongated
slot that allows the
bottom hole assembly to slide downwards rather than turning a corner. The
bottom hole
assembly most likely twisted out of plane due to the forces exerted upon the
bottom hole _
assembly as the build rate approaches the coiled tubing's yield radius of
curvature. These forces
likely cause the bottom hole assembly to twist off its plane affecting the
direction and location of
the acid tunnel.
Room The twisting or tilting of the bottom hole assembly out of its original
plane may
cause the acid tunnel to be formed in an area other than its intended
location. For example, the
tunnel may not extend through the very damaged or non-producing zone as
originally intended.
The rotation of the bottom hole assembly may also cause the tunnel to travel
substantially
parallel with the wellbore rather than substantially transverse limiting the
number of tunnels that
may be created as well as limiting the beneficial affects from the acid
tunnel.
100091 In light of the foregoing, it would be desirable to provide a bottom
hole assembly
that has a reduced build rate, but still create a tunnel that is substantially
transverse to the
wellbore. It would further be desirable to provide a bottom hole assembly with
two knuckle
joints to increase the overall radius of curvature of the bottom hole assembly
above the yield
radius of curvature of the coiled tubing. It would be desirable to orient the
two knuckle joints
such that the joints would bend in the same plane. It may also be desirable to
provide a bottom
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hole assembly with an extendable or telescopic wand to aid in the formation of
an acid tunnel. It
would also be desirable to provide a nozzle adapted to form an acid tunnel
that encourages the
bottom hole assembly to remain in its original plane as the acid tunnel is
created. Moreover, it
would be desirable to have the ability to adjust the angles of the knuckle
joints during lateral
initiation and navigation through the lateral tunnel.
[am] The present invention is directed to overcoming, or at least reducing the
effects of,
one or more of the issues set forth above.
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SUMMARY OF THE INVENTION
prorn The present invention provides assemblies and methods for lateral
tunneling
within a wellbore whereby the assembly is adapted to adjust its angle during
lateral tunneling. In
an exemplary embodiment of the present invention, an apparatus comprises a
tool assembly
having an internal fluid passage, coiled tubing connected to the tool
assembly, a first and second
reversible knuckle joint, a wand having, wherein the first and second
reversible knuckle joints
are adapted to adjust angles during tunneling. The knuckle joints are adapted
to adjust in
response to geometrical constraints within the lateral window and the lateral
itself. The knuckle
joints are further adapted to adjust in response to the set down weight on the
tool, when seeing
full differential pressure. Moreover, the knuckle joints have the ability to
be straightened by
external mechanical forces on the bottom hole assembly.
loom An exemplary method of the present invention provides a method of
creating a
lateral tunnel within a wellbore, the method comprising the steps of:
connecting a bottom hole
assembly to coiled tubing, the bottom hole assembly comprises an upper
reversible knuckle joint,
a lower reversible knuckle joint, and a nozzle located below the lower
reversible knuckle joint;
positioning the bottom hole assembly at a desired location within the
wellbore; actuating at least
one of the upper or lower reversible knuckle joints, wherein the nozzle moves
towards the
wellbore; initiating a lateral tunnel substantially transverse to the
wellbore, thereby creating a
lateral window; adjusting an angle of at least one of the upper or lower
reversible knuckle joints
such that the bottom hole assembly is allowed to move into the lateral window;
and creating the
lateral tunnel.
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BRIEF DESCRIPTION OF TILE DRAWINGS
[0013] Figure 1 shows a current bottom hole assembly used to create an acid
tunnel off a
wellbore, the assembly having a single pressure elbow that moves a nozzle into
contact with the
wellbore.
100141 Figure 2 shows the bottom hole assembly of Figure 1 starting to create
a tunnel in
the wellbore.
[0015] Figure 3 shows one embodiment of a bottom hole assembly that may be
used to
create an acid tunnel off a wellbore, the bottom hole assembly including two
knuckle joints to
increase the radius of curvature of the bottom hole assembly while providing
that the tunnel is
substantially transverse to the wellbore.
[0016] Figure 4 shows the bottom hole assembly of Figure 3 starting to create
a tunnel
that is substantially transverse to the wellbore.
[0017] Figure 5 is the end view of one embodiment of a nozzle having fluid
ports in a
symmetrical pattern with flow channels in an asymmetrical pattern adapted to
form an elliptical
hole in a wellbore formation.
mois] Figure 6 is the side view of the nozzle having flow channels in an
asymmetrical
pattern shown in Figure 5.
[0019] Figure 7 shows the bottom hole assembly utilizing reversible knuckle
joints
according to an alternative exemplary embodiment of the present invention.
1007.01 While the invention is susceptible to various modifications and
alternative forms,
specific embodiments have been shown by way of example in the drawings and
will be described
in detail herein. However, it should be understood that the invention is not
intended to be limited
to the particular forms disclosed. Rather, the intention is to cover all
modifications, equivalents
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and alternatives falling within the spirit and scope of the invention as
defined by the appended
claims.
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DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0021] Illustrative embodiments of the invention are described below as they
might be
employed in a bottom hole assembly having a radius of curvature that is
greater than the yield
radius of curvature of coiled tubing and that may be used to produce an acid
tunnel transverse to
a wellbore. In the interest of clarity, not all features of an actual
implementation are described in
this specification. It will of course be appreciated that in the development
of any such actual
embodiment, numerous implementation-specific -decisions must be made to
achieve the
developers' specific goals, such as compliance with system-related and
business-related
constraints, which will vary from one implementation to another. Moreover, it
will be
appreciated that such a development effort might be complex and time-
consuming, but would
nevertheless be a routine undertaking for those of ordinary skill in the art
having the benefit of
this disclosure.
[00221 Further aspects and advantages of the various embodiments of the
invention will
become apparent from consideration of the following description and drawings.
[00231 Figure 1 shows the configuration of a typical bottom hole assembly 100
that is
used to create an acid tunnel 30 (shown in Figure 2) within the formation 20
such that the tunnel
30 is substantially transverse to the wellbore 10. The bottom hole assembly
100 is connected to
coiled tubing 5 by a coiled tubing connector 110. At the lower end of the
bottom hole assembly
100 is a pressure elbow 150 that is actuated to move a wand 160 and nozzle 170
towards the
wellbore 10. The bottom hole assembly 100 may include various components such
as a check
valve 120 and hydraulic disconnect 130 as would be appreciated by one of
ordinary skill in the
art.
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[0024] Acid is pumped at a high pressure down the coiled tubing and through
the bottom
hole assembly 100 until the acid exits the nozzle 170. The back pressure from
the nozzle causes
the pressure elbow 150 to be actuated positioning the nozzle 170 against the
wellborn. At this
position, the acid exiting the nozzle begins to dissolve the formation 20
creating a tunnel 30 as
shown in Figure 2. The coil tubing is then lowered into the wellbore 10
advancing the formation
of the tunnel 30 through the formation 20. As the tunnel 30 is created the
bottom hole assembly
100 advances into the tunnel 30. However, the geometry of the bottom hole
assembly 100
dictates the radius through which the bottom hole assembly 100 may travel.
Specifically, the
distance from the nozzle 170 to the pressure elbow 150, the angle of the
pressure elbow 150, and
the distance from the pressure elbow 150 to the coiled tubing connector 110
determines the
radius through which the bottom hole assembly 100 may travel.
100251 With the configuration shown in Figure 1, the pressure elbow 150
generally is
actuated to an initial kickover angle 0 from the centerline of the bottom hole
assembly 100 to
ensure that the nozzle 170 comes into contact with the wellbore 10. This is
done to ensure that
the acid begins to create a tunnel into the side of the wellbore 10. The
geometry of the bottom
hole assembly 100 as well as the wellbore 10 dictates the initial kickover
angle 0 required to have
the nozzle 170 contact the side of the wellbore 10 as illustrated by the
following formula whereas
1 is the length of the wand 160, D is the diameter of the wellbore 10, and d
is diameter of the
bottom hole assembly 100.
I sin 0 > D ¨ d/2
100261 The above formula illustrates that in order to have the nozzle 170
touch the side of
the wellbore 10 the length 1 of the wand multiplied the sine of the angle 0
must be greater than
the diameter D of the wellbore minus 1/2 of the diameter d of the bottom hole
assembly. Thus,
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increasing the wand length decreases the angle 0 necessary to touch the
wellbore. As discussed
above, increasing the length of the wand 160 increases the chance that the
bottom hole assembly
100 may become cam locked within the tunnel 30. However, increasing the
initial kickover
angle 0 also decreases the radius of curvature such that the radius of
curvature of the bottom hole
assembly 100 may be smaller than the yield radius of the coiled tubing 5.
10021 Once the tunnel is begun, the pressure elbow 150 is bent to its maximum
kickover
angle 0 to increase the build angle of the tunnel as shown in Figure 2.
Typically the maximum
kickover angle 0 is less than fifteen degrees. This current configuration of
the bottom hole
assembly creates a radius of curvature of the bottom hole assembly 100 that is
smaller than the
yield radius of curvature of coiled tubing which may cause unacceptable forces
on the coiled
tubing as it creates a tunnel 30. The length of the wand 160 may be increased
in an effort to
decrease the kickover angle 0 required to touch the wellbore with the nozzle
170. However,
increasing the length of the wand 160 also increases the chance that the
bottom hole assembly
100 will become cam locked within the tunnel 30. For at least these reasons,
it may be beneficial
to provide a new configuration that may overcome these potential issues.
[0028) Figure 3 shows the configuration of one embodiment of a bottom hole
assembly
100 that includes a first knuckle joint 155 and a second knuckle joint 156
used to create an acid
tunnel 30 within the formation 20 so that the tunnel 30 is substantially
transverse to the wellbore
10. The two knuckle joints 155, 156 are actuated to touch the nozzle 170 to
the side of the
wellbore 10 and permits the use of a shorter wand 160 than the prior
configuration. The two
knuckle joints 155, 156 increases the radius of curvature of the bottom hole
assembly 100 while
increasing the attack angle of the nozzle 170 to the wellbore 10.
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[0029] Acid may be pumped at a high pressure down the coiled tubing and
through the
bottom hole assembly 100 until the acid exits the nozzle 170. With the nozzle
170 positioned
against the wellbore 10, the acid exiting the nozzle 170 begins to dissolve
the formation 20 and
create a tunnel 30 as shown in Figure 4. The coiled tubing may be lowered into
the wellbore 10
advancing the formation of the tunnel 30 through the formation 20. As the
tunnel 30 is created
the bottom hole assembly 100 advances into the tunnel 30. The use of two
knuckle joints 155,
156 provides that the tunnel 30 will be substantially transverse to the
wellbore by increasing the
starting angle of the tunnel, but without increasing the build angle of the
tunnel.
[0030] The use of two knuckles 155, 156 increases the lateral displacement of
the nozzle
170 with a smaller initial kickover angle 01, 02 for each knuckle. Assuming
that the length 1 of
the wand 160 is equal to the length between the first knuckle 155 and the
second knuckle 156
and that the initial kickover angle 01 for the first knuckle 155 is equal to
the kickover angle 92 for
the second knuckle 156, the following equation may be used to determine the
minimum kickover
angle 0 required for the nozzle 170 to touch the wall of the wellbore 10.
1(sin 0+ sin 20) > D ¨ dI2
[0031] The above formula illustrates that a smaller initial kickover angle is
required to
touch the nozzle 170 to the wall of the wellbore 10 when the bottom hole
assembly 100 includes
two knuckle joints 155, 156. The use of two knuckle joints provides that a
smaller maximum
kickover angle may be used for each knuckle joint without sacrificing a quick
build angle for the
tunnel. The use of two knuckle joints also permits a smaller maximum kickover
angle may be
used to create a tunnel substantially transverse to the wellbore. The use of
smaller maximum
kickover angles may be used to increase the radius of curvature of the bottom
hole assembly
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above the yield radius of curvature of coiled tubing while still providing a
sufficient attack angle
and build angle.
[0032] Figures 5 and 6 show one embodiment of a nozzle 170 that has been
adapted to
promote the formation of an elliptical hole in a wellbore formation. The
nozzle 170 includes
fluid ports 173 that may be angled, as shown in Figure 5, to promote the
creation of an elliptical
shaped hole. The nozzle 170 also includes a central fluid port 174. The nozzle
170 includes a
plurality of grooves or flow channels 171, 172 on the exterior of the nozzle
170 that provide a
pathway for the acid to flow past the nozzle after it has been jetted against
the wellbore
formation. The size and placement of the grooves may be configured in an
asymmetrical pattern
to promote the formation of an elliptical hole by the nozzle 170. For example,
one set of grooves
172 may have a larger passage area that another set of grooves 171 allowing
more acid to pass
along the exterior of the nozzle 170. Portions of the wellbore may be
dissolved faster than the
rest of the wellbore due to a longer duration of exposure to the acid. The
differences in acid flow
along the nozzle may be used to promote the formation of an elliptical hole in
the wellbore. As
would be appreciated by one of ordinary skill the art having the benefit of
this disclosure, the
configuration and sizes of the exterior flow paths may be varied within the
spirit of this
invention.
[0033) Figure 7 illustrates an alternative embodiment of the present invention
utilizing
double reversible knuckle joints. Here, bottom hole assembly 100 is
constructed as previously
described except that reversible knuckle joints 180,182 are used. Unlike
knuckle joints 155,156,
once knuckle joints 180,182 are activated, they remain flexible rather than
rigid. Reversible
knuckle joints 180,182 may be pressure or flow activated as known in the art.
An example of a
reversible knuckle joint which may be utilized in the present invention
include those disclosed in
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U.S. Patent No. 6,527,067, issued on March 4, 2003 to John E. Ravensbergen et
al, entitled
"LATERAL ENTRY GUIDANCE SYSTEM (LEGS)," owned by the Assignee of the present
invention, BJ Services Company of Houston, Texas, which is hereby incorporated
by reference in
its entirety. Please note, however, those ordinarily skilled in the art having
the benefit of this
disclosure realize other comparable knuckle joints may be utilized with the
present invention.
[0034] Once activated, knuckle joints 180,182 bend to an angle determined by
the space
available down hole, or until a preset limit is reached. As the new lateral is
initiated, the
available space for the tool changes. For the tool to navigate through the
newly created lateral
window, knuckle joints 180,182 must adjust their angles to exit through the
window and into the
new lateral tunnel 30. Knuckle joints 180,182 must adjust their angles in
response to loads
applied to the tool by the walls of wellbore 10 and, therefore, knuckles
180,182 must be
reversible (i.e., down hole loads can overcome the activating drive device
(e.g. pressure)). Those
ordinarily skilled in the art having the benefit of this disclosure realized
there are a variety of
reversible knuckle joints which may be utilized with this exemplary embodiment
of the present
invention. Moreover, although described herein as having two reversible
knuckle joints, those
ordinarily skilled in the art having the benefit of this disclosure realize
more knuckle joints may
be utilized_
100351 For the clownhole assembly 100 to navigate into a newly constructed
lateral 30,
the initial angle of attack of the assembly 100 needs to be controlled so as
to limit the dogleg
entry angle (a) into the new lateral 30. Too high an attack angle will prevent
the assembly 100
from navigating through the window to the new lateral 30. To ensure this
scenario does not
occur, a limit will sometimes be required on the angle that the lower knuckle
joint 182 can
assume. This limit is calculated using geometry, and is based on ensuring that
the maximum
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straight length of assembly 100 above the nozzles 170 can turn the corner into
the new lateral 30.
This maximum dogleg angle (a) is derived using the following equation:
LDmotherbore ¨ D ¨ rt.., = sin a,õ,õ
toot¨
sin 0 sin(amax ¨e) sin = sin(an. ¨e)
Minimumfor0<8<a.
The maximum dogleg angle (an.) is a function of the hole and tool diameters,
and the length of
straight tool (L1001) that must navigate through the junction. =
The actual angle of attack (i.e., dogleg entry angle) (a) is determined by the
tool length (L10.1), the
wand length (Lwand) and the maximum lower knuckle joint angle (fl,,). The
actual angle of
attack (a) is derived using the following equation:
Lt./ sin(a ) + Lwand = sin a + rnozzie = Cosa = Drnotherbore rtod
With the condition that /3,nar < a.
For the tool to navigate through the junction, a must be less than or equal to
aõõõ so defining
fl,. This embodiment of the tool requires that the lower knuckle joint
activate preferentially to
the upper knuckle joint. Those ordinarily skilled in the art having the
benefit of this disclosure
realize that, if more than two reversible knuckle joints are utilized, the
before-mentioned math
may be tailored to fit such embodiments.
[0036] It is sometimes beneficial to enlarge the mother bore and lateral
tunnel diameters
at the lateral initiation point. Accordingly, in yet another exemplary
embodiment, a fluid, such as
acid, for example, may be pumped through the assembly 100 in order to enlarge
the wellbore 10
and/or lateral tunnel 30, in order to improve navigation through tunnel 30.
The benefit of
enlarging the wellbore and lateral diameters is to permit a longer tool length
to navigate the
junction, and/or provide for a higher kick-out angle for the lateral 30. To
achieve this, assembly
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100 is positioned at the intended lateral tunnel initiation point and acid is
pumped through
assembly 100. In one exemplary embodiment, assembly 100 is stationary in the
kicked out
position, and acid is pumped for several minutes Or longer, and may involve
the pumping of a
higher strength acid. However, those ordinarily skilled in the art having the
benefit of this
disclosure reali7e a variety of fluids may be utilized for this purpose and
the fluid may be
pumped at different points in the lateral tunneling process.
[0037J An exemplary embodiment of the present invention provides an apparatus
for
lateral tunneling within a wellbore, the apparatus comprising: a tool assembly
having an upper
end and a lower end, the tool assembly having an internal fluid passage;
coiled tubing connected
to the upper end of the tool assembly, the coiled tubing is in fluid
communication with the
internal passage of the tool assembly; a first reversible knuckle joint
connected to the tool
assembly, the first reversible knuckle joint having a central bore in fluid
communication with
internal passage of the tool assembly; a second reversible knuckle joint, the
second reversible
knuckle joint having a central bore in communication with the central bore of
the first reversible
knuckle joint, the second reversible knuckle joint being connected below the
first reversible
knuckle joint; a wand having a first end, a second end, and a central bore,
the first end of the
wand being connected below the second reversible knuckle joint, wherein the
central bore of the
wand is in fluid communication with the central bore of the second reversible
knuckle joint; and
a nozzle connected to the second end of the wand, wherein the nozzle is in
fluid communication
with the coiled tubing, wherein the first and second reversible knuckle joints
are adapted to
adjust angles during tunneling.
[00381 In yet a. further exemplary embodiment, the wand is telescopic. In
another
embodiment, the first reversible knuckle joint and the second reversible
knuckle joint are adapted
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to bend in the same plane. Also, in another exemplary embodiment, the radius
of curvature of
the apparatus is more than the yield radius of curvature of the coiled tubing.
In another
embodiment, the angles of the first and second reversible knuckle joints are
adjusted in response
to loads applied to the apparatus.
100391 Yet another exemplary embodiment of the present invention provides a
bottom
hole assembly for lateral tunneling in a wellbore, the bottom hole assembly
comprising: coiled
tubing connected to the bottom hole assembly, a nozzle connected adjacent a
lower end of the
bottom hole assembly, the nozzre being in fluid communication with the coiled
tubing; a first
reversible knuckle joint, the first reversible knuckle joint having a bore and
being connected to
the bottom hole assembly below the coiled tubing; and a second reversible
knuckle joint, the
second reversible knuckle joint having a bore and being connected to the
bottom hole assembly
below the first reversible knuckle joint, wherein the first and second
reversible knuckle joints
allow the bottom hole assembly to bend in a first direction and to bend in a
second direction
opposite the first direction. In another embodiment, the first and second
reversible knuckle joints
are pressure operated.
100401 In yet another exemplary embodiment, the bottom hole assembly further
comprises a wand having a central bore, a first end, and a second end, wherein
the first end of the
wand is connected below the second reversible knuckle joint and the nozzle is
connected to the
second end of the wand. In another embodiment, the wand comprises a
telescoping section. In
yet another exemplary embodiment, the first reversible knuckle joint and the
second reversible
knuckle joint are adapted to bend in substantially the same plane. In another
embodiment, the
nozzle comprises a plurality of ports in an asymmetrical pattern. In another
embodiment, the
asymmetrical pattern is adapted to form an elliptical hole in a wellbore
formation. In yet another
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exemplary embodiment, the nozzle comprises a plurality of ports in a
symmetrical pattern and a
plurality of flow channels in an asymmetrical pattern. In another embodiment,
the angles of the
first and second reversible knuckle joints are adjusted in response to loads
applied to the bottom
hole assembly.
[00411 An exemplary method of the present invention provides a method of
creating a
lateral tunnel within a wellbore, the method comprising the steps of:
connecting a bottom hole
assembly to coiled tubing, the bottom hole assembly comprises an upper
reversible knuckle joint,
a lower reversible knuckle joint, and a nozzle located below the lower
reversible knuckle joint;
positioning the bottom hole assembly at a desired location within the
wellbore; actuating at least
one of the upper or lower reversible knuckle joints, wherein the nozzle moves
towards the
wellbore; initiating a lateral tunnel substantially transverse to the
wellbore, thereby creating a
lateral window; adjusting an angle of at least one of the upper or lower
reversible knuckle joints
such that the bottom hole assembly is allowed to move into the lateral window;
and creating the
lateral tunnel. The method may further comprise the step of extending the
nozzle towards the
lateral tunnel. Yet another exemplary method comprises the step of orienting
the upper
reversible knuckle joint and the lower reversible knuckle joint such that the
knuckle joints bend
on substantially the same plane.
[00421 Yet another exemplary method comprises the step of moving the coiled
tubing
downhole to create a longer lateral tunnel, the angle of at least one of the
upper or lower '-
reversible knuckle joints being adjusted as the bottom hole assembly moves
through the lateral
tunnel. Another method may comprise the steps of locating the nozzle at a
different location in
the wellbore, and pumping acid down the coiled tubing and jetting acid out of
the nozzle,
wherein the acid creates a second acid tunnel substantially transverse to the
wellbore. In yet
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another method, the step of creating the lateral tunnel comprises jetting
fluid out of a nozzle of
the bottom hole assembly in a symmetrical pattern while allowing the fluid to
flow back past the
nozzle in an asymmetrical pattern. Another exemplary method comprises the step
of pumping
acid to enlarge at least one of the wellbore or lateral tunnel diameters such
that the bottom hole
assembly is allowed to move through the lateral tunnel more efficiently. In
yet another method,
the acid is pumped while the bottom hole assembly angled in a stationary
position.
[0043] Yet another exemplary method of the present invention provides a method
of
creating a lateral tunnel within a wellbore, the method comprising the steps
of: connecting a
bottom hole assembly to coiled tubing, the bottom hole assembly being adapted
to create a lateral
tunnel substantially transverse to the wellbore; positioning the bottom hole
assembly at a desired
location within the wellbore; actuating the bottom hole assembly such that the
bottom hole
assembly bends to a first angle towards the wellbore; initiating the lateral
tunnel, thereby creating
a lateral window; adjusting the bottom hole assembly such that the bottom hole
assembly bends
to a second angle, thereby allowing the bottom hole assembly to move into the
lateral window;
and creating the lateral tunnel. Yet another method comprises the step of
adjusting the second
angle of the bottom hole assembly as the bottom hole assembly moves through
the lateral tunnel.
Yet another method comprises the step of adjusting the first or second angle
in response to loads
applied to the bottom hole assembly. Yet another exemplary method comprises
the step of
reversing at least one of the bending motions. Yet another exemplary method
comprises the step
of creating an elliptical lateral tunnel. Moreover, another exemplary
embodiment, comprises the
step of pumping fluid to enlarge at least one of the wellbore or lateral
tunnel diameters.
[0044] Although various embodiments have been shown and described, the
invention is
not so limited and will be understood to include all such modifications and
variations as would
CA 02642704 2008-11-03
, =
be apparent to one skilled in the art. Accordingly, the invention is not to be
restricted except in
light of the attached claims and their equivalents.
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