Note: Descriptions are shown in the official language in which they were submitted.
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TIMED IMPACT DRILL BIT STEERING
TECHNICAL FIELD
The present disclosure relates generally to equipment utilized and operations
performed in conjunction with a subterranean well and, in an embodiment
described herein,
more particularly provides for timed impact drill bit steering.
BACKGROUND
It is frequently desirable to drill a wellbore in a selected direction, for
example, to
steer toward a hydrocarbon reservoir, or to steer away from a fault or a water
zone (although
in some circumstances, such as geothermal and conformance operations, it may
be desirable
to steer toward a fault or water zone). Therefore, it will be appreciated that
improvements are
needed in the art of steering a drill bit to thereby drill a wellbore in a
desired direction.
SUMMARY
In accordance with a general aspect, there is provided a method of steering a
drill bit
of a drill string while drilling a wellhore, the method comprising: rotating
the drill string,
wherein a longitudinal axis of the drill bit is angularly offset from a
longitudinal axis of the
drill string by a bend; delivering, using an impact tool in the wellbore, a
single impact for
each azimuthal rotation of the drill bit about the longitudinal axis of the
drill string, the
impact being directed along both the longitudinal axis of the drill string and
the longitudinal
axis of the drill bit when the longitudinal axis of the drill bit is oriented
in a desired azimuthal
direction relative to the longitudinal axis of the drill string so as to
direct the drill bit in the
desired azimuthal direction due to the drill bit being angularly offset from
the drill string;
stopping the rotation of the drill string when the longitudinal axis of the
drill bit is oriented in
the desired azimuthal direction and after at least one impact is delivered
using the impact
tool; rotating the drill bit about its longitudinal axis using a mud motor;
sliding the drill string
when the drill string is not being rotated; and wherein the bend is
interconnected between the
drill bit and the impact tool and between the mud motor and the drill bit.
In accordance with another aspect, there is provided a method of steering a
drill bit of
a drill string while drilling a wellbore, the method comprising: rotating the
drill string,
wherein a longitudinal axis of the drill bit is angularly offset from a
longitudinal axis of the
drill string by a bend; delivering, using an impact tool in the wellbore, a
single impact for
each azimuthal rotation of the drill bit about the longitudinal axis of the
drill string, the
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impact being delivered along both the longitudinal axis of the drill string
and the longitudinal
axis of the drill bit when the longitudinal axis of the drill bit is oriented
in a desired azimuthal
direction relative to the longitudinal axis of the drill string so as to
direct the drill bit in the
desired azimuthal direction due to the drill bit being angularly offset from
the drill string,
wherein the longitudinal axis of the drill bit is longitudinally offset from
the longitudinal axis
of the drill string, wherein the impact is produced by energizing a
piezoelectric material;
stopping the rotation of the drill string when the longitudinal axis of the
drill bit is oriented in
the desired azimuthal direction and after at least one impact is delivered
using the impact
tool; rotating the drill bit about its longitudinal axis using a mud motor;
sliding the drill string
when the drill string is not being rotated; and wherein the bend is
interconnected between the
drill bit and the impact tool and between the mud motor and the drill bit.
In accordance with a further aspect, there is provided a method of steering a
drill bit
of a drill string while drilling a wellbore, the method comprising:
interconnecting a bend
between an impact tool and the drill bit, wherein a longitudinal axis of the
drill bit is
angularly offset from a longitudinal axis of the drill string by the bend;
interconnecting a mud
motor such that the bend is between the mud motor and the drill bit; rotating
the drill bit
about its longitudinal axis using the mud motor; sliding the drill string when
the longitudinal
axis of the drill bit is oriented in the desired azimuthal direction and the
drill string is not
being rotated; rotating the drill string after in the drill string; and during
steering of the drill
bit, for each azimuthal rotation of the drill bit about the longitudinal axis
of the drill string,
delivering a single impact using the impact tool in the wellbore when the
longitudinal axis of
the drill bit is oriented in the desired azimuthal direction relative to the
longitudinal axis of
the drill string.
In accordance with a still further aspect, there is provided a directional
drilling
system, comprising: a drill string; an impact tool interconnected in the drill
string and
comprising a wall disposed between an internal flow passage of the impact tool
and an
exterior of the impact tool; a bend interconnected in the drill string between
a drill bit and the
impact tool; a reciprocating mass disposed within the impact tool wall,
wherein a single
impact is delivered to a drill bit in response to displacement of the
reciprocating mass; a drill
motor interconnected such that the bend is interconnected between the drill
motor and the
drill bit, wherein the drill motor is configured to rotate the drill bit about
a longitudinal axis
of the drill bit whether or not the drill string is being rotated, wherein the
longitudinal axis of
the drill bit is angularly offset from a longitudinal axis of the drill string
by the bend; a
controller configured to steer the drill bit using the impact tool: and
wherein the impact tool is
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configured to deliver the impact to the drill bit in response to the
longitudinal axis of the drill
bit being at a desired azimuthal direction relative to the longitudinal axis
of the drill string
whether or not the drill string is being rotated.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a directional drilling
system and associated method which may embody principles of
the present disclosure.
FIG. 2 is a schematic depiction of relative
relationships of axes of a drill string in the system and
method of FIG. 1.
FIG. 3 is a schematic depiction of an azimuthal
direction of a drill bit axis relative to a drill string
axis.
FIGS. 4-7 are schematic cross-sectional views of
various configurations of an impact tool which may be used
in the system and method of FIG. 1.
DETAILED DESCRIPTION
Representatively illustrated in FIG. 1 is a
directional drilling system 10 and associated method which
can embody principles of the present disclosure. It should
be clearly understood, however, that the principles of this
disclosure are not limited at all to the specific details
of the system 10 and method described herein. Instead, the
system 10 and method are provided as merely one example of
how the principles of this disclosure can be effectively
used for steering a drill bit, and for thereby drilling a
wellbore in a desired direction.
As depicted in FIG. 1, a wellbore 12 is being drilled
with a generally tubular drill string 14. A drill bit 16
is connected at a lower end of the drill string 14.
Rotation of the drill string 14 (e.g., by a drilling rig at
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or near the earth's surface) also rotates the drill bit 16,
whereby the drill bit cuts into the earth to drill the
wellbore 12.
A mud motor 18 is also preferably interconnected as
part of the drill string 14. The mud motor 18 is of the
type well known to those skilled in the art, which rotates
the drill bit 16 in response to flow of drilling fluid
through the drill string 14. Thus, the mud motor 18 can be
used to rotate the drill bit 16 even if the drill string 14
above the mud motor is not rotated.
A bend 20 is also interconnected in the drill string
14. Although not perceptible in FIG. 1, the bend 20
provides a small (e.g., approximately 1.5 degree) deviation
in a longitudinal axis of the drill string 14. The bend 20
is of the type well known to those skilled in the art,
which is typically used for directional drilling when a mud
motor (such as the mud motor 18) rotates a drill bit (such
as the drill bit 16).
Indeed, the bend 20 can be used for steering the drill
bit 16 in the system 10 when the mud motor 18 rotates the
drill bit (e.g., when the drill string 14 is not rotated
from the surface). However, this disclosure provides for
steering the drill bit 16 when the drill string 14 is
rotated and the mud motor 18 is not used for rotating the
drill bit in response to flow of drilling fluid through the
mud motor.
Interconnected in the drill string 14 above the mud
motor 18 is an impact tool 22. The impact tool 22 delivers
timed periodic impacts to the drill bit 16 as described
more fully below. The timing of the impacts is controlled
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by a controller 24, which is in communication with a sensor
assembly 26, and which can be remotely operable (e.g., from
the surface) via various forms of wired and wireless
telemetry.
The sensor assembly 26 can be of the type well known
to those skilled in the art as a measurement while drilling
(MWD) system. Such MWD systems are capable of measuring a
multitude of drilling parameters, and in this system 10 the
sensor assembly 26 is beneficially capable of detecting an
orientation of the drill string 14 and an azimuthal
direction of the drill bit 16 relative to the longitudinal
axis of the drill string above the bend 20.
Referring additionally now to FIG. 2, a schematic
depiction of the longitudinal axis 28 of the drill string
14 is representatively illustrated. The bend 20 in the
drill string 14 is exaggerated in FIG. 2 for illustrative
purposes.
The longitudinal axis 28 of the drill string 14 above
the bend 20 is designated as 28a, the longitudinal axis of
the drill string at the bend is designated as 28b, and the
longitudinal axis of the drill string below the bend is
designated as 28c in FIG. 2. Note that the longitudinal
axis 28c of the drill string 14 below the bend 20 coincides
with the longitudinal axis of the drill bit 16.
It will be appreciated that the axis 28c of the drill
bit 16 deviates from the longitudinal axis 28a of the drill
string 14 above the bend 20 by an angle A. This angle A
may be relatively small, but when compounded over distances
of, for example, a hundred meters or more, can produce a
much larger change in direction of the wellbore 12.
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Note that, although the axis 28a is depicted in FIG. 2
as being vertical, the axis 28a is described herein as
being -above" the bend 20, and the axis 28c is described
herein as being "below" the bend, it is not necessary in
keeping with the principles of this disclosure for the axis
28a to be vertical, since the axis 28a could be generally
horizontal, deviated, inclined relative to vertical, etc.
The terms "above," "below" and similar directional terms
are used for convenience to refer to positions relative to
proximal and distal ends of the drill string 14. For
example, the axis 28a is "above" the bend 20, in that it is
nearer the proximal end of the drill string 14 (e.g.,
closer to the surface), and the axis 28c is "below" the
bend, in that it is nearer the distal end (in this case,
the bottom end) of the drill string (e.g., farther from the
surface).
The impact tool 22 is used to deliver an impact
(represented by arrows 30 in FIG. 2) directed along the
longitudinal axis 28 of the drill string 14. Due to the
bend 20 in the drill string 14, the impact 30 is directed
both along the axis 28a of the drill string 14 above the
bend 20, and along the axis 28c of the drill string and
drill bit 16 below the bend. This arrangement provides
advantages to the system 10 as described more fully below.
Referring additionally now to FIG. 3, a schematic view
of the relationship between the azimuthal direction of the
drill bit 16 (represented by arrow 32 in FIG. 3) and the
drill string axis 28a is representatively illustrated.
That is, FIG. 3 presents a view downward along the axis 28a
and, due to the angle A by which the drill bit axis 28c
deviates from the drill string axis 28a, the drill bit 16
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has an azimuthal direction 32 relative to the drill string
axis 28a.
As the drill string 14 rotates, the azimuthal
direction 32 of the drill bit axis 28c relative to the
drill string axis 28a also rotates (as indicated by arrow
34 in FIG. 3). In one important feature of the system 10,
the impact tool 22 delivers the impact 30 to the drill bit
16 when (and preferably only when) the azimuthal direction
32 of the drill bit axis 28e relative to the drill string
axis 28a is in a desired direction.
For example, if it is desired to steer the drill bit
16 in an azimuthal direction of 30 degrees relative to the
drill bit axis 28a, then the impact 30 would be delivered
to the drill hit 16 when the drill bit axis 28c is oriented
in an azimuthal direction 32 of 30 degrees relative to the
drill string axis 28a (as depicted in FIG. 3). Since the
azimuthal direction 32 of the drill bit axis 28c rotates
about the drill bit axis 28a (as represented by arrow 34 in
FIG. 3) as the drill string 14 rotates, the azimuthal
direction of the drill bit axis will coincide with the
desired azimuthal direction once for every rotation of the
drill string 14.
Preferably, the impact tool 22 delivers the impact 30
to the drill bit 16 once for each rotation of the drill
string 14 (when the azimuthal direction 32 of the drill bit
axis 28c is oriented toward the desired direction), but the
impact could be delivered every other rotation, every third
rotation, multiple times per rotation, or at other times,
in keeping with the principles of this disclosure.
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The controller 24 controls the timing of the impact
30, based on the detection of the orientation of the drill
bit axis 28c relative to the drill string axis 28a as
sensed by the sensor assembly 26, and preferably based on
commands, data, instructions, etc. received from a remote
location (such as the surface) via telemetry. Any form of
telemetry may be used, for example, wired or wireless
telemetry. Wireless telemetry may include acoustic,
electromagnetic, pressure pulse (positive and/or negative),
pipe manipulation, etc. Wired telemetry may be via
conductors internal to, external to, or in a wall of the
drill string 14, etc.
The controller 24 may be used to activate or
deactivate the impact tool 22 (e.g., to cause the impact
tool to begin or cease delivering the impact 30 to the
drill bit 16), to change the frequency of the impact (e.g.,
the number of impacts per rotation of the drill string 14),
to change the desired azimuthal direction for steering the
drill bit, to change the impact force delivered, etc. Any
parameter related to the delivery of the impact 30 by the
impact tool 22 may be controlled using the controller 24,
in keeping with the principles of this disclosure.
Referring additionally now to FIGS. 4-7, various
configurations of the impact tool 22 are schematically and
representatively illustrated. However, it should be
clearly understood that these examples of configurations of
the impact tool 22 are not to be taken as limiting the
principles of this disclosure to the depicted examples.
Instead, the examples depicted in FIGS. 4-7 are intended to
demonstrate that a wide variety of impact tool
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configurations are possible in keeping with the principles
of this disclosure.
In FIG. 4, the impact tool 22 is depicted in a
configuration in which a valve or other flow restricting
device 36 is used to periodically close off or restrict
flow of the drilling fluid 38 through a passage extending
longitudinally through the impact tool. When the flow of
the drilling fluid 38 is restricted by the device 36, the
momentum of the fluid is converted to a force transmitted
as the impact 30 through an outer housing 42 of the impact
tool 22.
The device 36 could be provided as a spool valve,
rotary valve, poppet valve or any other type of valve.
However, it is not necessary for flow of the fluid 38 to be
entirely prevented in order for the impact 30 to be
generated, since a sufficient change in momentum of the
fluid through the passage 40 could result from
substantially restricting (rather than entirely preventing)
the flow of the fluid.
Operation of the device 36 (for example, the timing of
the restriction to flow of the fluid 38 through the passage
40) is controlled by the controller 24, as described above.
Lines 44 are depicted in FIG. 4 for connecting the device
36 to the controller 24, but it should be understood that
the controller could control operation of the device
mechanically, hydraulically, electrically, optically, or in
any other manner, in keeping with the principles of this
disclosure.
In FIG. 5, the impact tool 22 is depicted as including
a valve 46, a piston 48, a mass 50, a biasing device 52 and
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a shoulder 54. When the impact 30 is to be delivered to
the drill bit 16, the valve 46 is opened, thereby exposing
the piston 48 to fluid pressure in the passage 40, and the
piston displaces the mass 50 into contact with the shoulder
54. The timing of the opening of the valve 46 is
controlled by the controller 24, as described above.
In FIG. 6, the impact tool 22 is depicted as including
a solenoid 56 which is used to displace the mass 50 into
contact with the shoulder 54 to thereby produce the impact
30. The timing of energizing the solenoid 56 is controlled
by the controller 24, as described above.
In FIG. 7, the impact tool 22 is depicted as including
a piezoelectric material 58 in the form of a stack of
annular disks 60. When an electrical potential is applied
across the piezoelectric material 58, the material distorts
and thereby produces the impact 30. The timing of applying
the electrical potential across the piezoelectric material
58 is controlled by the controller 24, as described above.
Although the mud motor 18, bend 20, impact tool 22,
controller 24 and sensor assembly 26 are separately
described above, any of these elements could be combined
with any of the other elements, as desired. For example,
the mud motor 18 could be provided with the bend 20 as a
single assembly, the impact tool 22 and controller 24 could
be provided as a single assembly, the mud motor 18 can be
provided with the sensor assembly 26 for detecting when the
drill bit axis 28c is pointing in the desired azimuthal
direction relative to the drill string axis 28a, etc.
The mud motor 18 in conjunction with the bend 20 may
be used for directional drilling when the drill string 14
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is not being rotated, which is known to those skilled in
the art as directional drilling in sliding mode. Thus,
although the mud motor 18 is not necessary for directional
drilling when the drill string 14 is being rotated and the
impact tool 22 is being used to deliver the impact 30 to
the drill bit 16, its presence in the drill string is
useful in that it provides the capability of directional
drilling in sliding mode, if desired.
It may now be fully appreciated that the above
disclosure provides several advancements to the art of
steering a drill bit and directional drilling of a
wellbore. In particular, the drill bit 16 can be steered
while rotating the drill string 14 by delivering an impact
30 to the drill bit when an azimuthal direction 32 of its
axis 28c is in a desired direction relative to an axis 28a
of the drill string. The impact 30 being delivered to the
drill bit 16 when its axis 28c is oriented in the desired
azimuthal direction 32 causes the wellbore 12 to be
preferentially drilled in the desired direction.
The above disclosure provides to the art a method of
steering a drill bit 16 while drilling a wellbore 12. The
method can include periodically delivering an impact 30 to
the drill bit 16 as the drill bit is rotated by a drill
string 14, and the impact 30 being delivered to the drill
bit 16 when an axis 28c of the drill bit is oriented in a
desired azimuthal direction 32 relative to an axis 28a of
the drill string 14.
The impact 30 can be directed along the drill string
axis 28a and along the drill bit axis 28c.
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The drill bit axis 28c preferably rotates about the
drill string axis 28a while the impact 30 is delivered to
the drill bit 16.
The impact 30 may be delivered to the drill bit 16
only when the drill bit axis 28c is oriented in the desired
azimuthal direction 32 relative to the drill string axis
28a.
A bend 20 may be interconnected between the drill bit
16 and an impact tool 22 which produces the impact 30. A
mud motor 18 may be interconnected between the impact tool
22 and the bend 20.
Periodically delivering the impact 30 to the drill bit
16 can be performed by, for example, periodically
restricting flow of fluid 38 through the drill string 14,
periodically displacing a mass 50 with a piston 48,
periodically displacing a mass 50 by energizing a solenoid
56, or periodically energizing a piezoelectric material 58.
Periodically delivering the impact 30 to the drill bit
16 may include detecting the azimuthal direction 32 of the
drill bit axis 28c relative to the drill string axis 28a
utilizing a sensor assembly 26 interconnected in the drill
string 14.
The method can include changing the desired azimuthal
direction 32 of the drill bit axis 28c from a remote
location. Changing the desired azimuthal direction 32 may
be performed in part by transmitting a command from the
remote location via a telemetry signal.
Also provided by the above disclosure is a method of
steering a drill bit 16 while drilling a wellbore 12, which
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method can include: interconnecting a bend 20 in a drill
string 14 between an impact tool 22 and the drill bit 16,
and periodically delivering an impact 30 from the impact
tool 22 to the drill bit 16 as the drill bit is rotated by
the drill string 14.
A directional drilling system 10 is also described
above. The system 10 can include a drill string 14 having
a bend 20 interconnected therein, an impact tool 22, and a
drill bit 16. The bend 20 is preferably interconnected in
the drill string 14 between the drill bit 16 and the impact
tool 22.
The impact tool 22 can deliver an impact 30 to the
drill bit 16, with the impact 30 being directed along an
axis 28c of the drill bit 16. The impact tool 22 may
deliver the impact 30 to the drill bit 16 when an axis 28c
of the drill bit 16 is oriented in a desired azimuthal
direction 32 relative to an axis 28a of the drill string 14
above the bend 20.
A sensor assembly 26 interconnected in the drill
string 14 may sense an azimuthal direction 32 of an axis
28c of the drill bit 16 relative to an axis 28a of the
drill string 14. A controller 24 may cause the impact tool
22 to deliver an impact 30 to the drill bit 16 in response
to the azimuthal direction 32 of the drill bit axis 28c
being at a desired azimuthal direction. The desired
azimuthal direction 32 may be changed from a remote
location.
It is to be understood that the various embodiments of
the present disclosure described herein may be utilized in
various orientations, such as inclined, inverted,
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horizontal, vertical, etc., and in various configurations,
without departing from the principles of the present
disclosure. The embodiments are described merely as
examples of useful applications of the principles of the
disclosure, which is not limited to any specific details of
these embodiments.
Of course, a person skilled in the art would, upon a
careful consideration of the above description of
representative embodiments of the disclosure, readily
appreciate that many modifications, additions,
substitutions, deletions, and other changes may be made to
the specific embodiments, and such changes are contemplated
by the principles of the present disclosure. Accordingly,
the foregoing detailed description is to be clearly
understood as being given by way of illustration and
example only, the spirit and scope of the present invention
being limited solely by the appended claims and their
equivalents.
