Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STOCHASTIC BIT NOISE CONTROL
[0001] This application claims the benefit of and is a continuation-in-part of
co-pending
U.S. Application No. 11/839,381 filed on August 15, 2007, entitled SYSTEM AND
METHOD FOR CONTROLLING A DRILLING SYSTEM FOR DRILLING A
BOREHOLE IN AN EARTH FORMATION, which is hereby expressly incorporated by
reference in its entirety for all purposes.
[0002] This application is related to U.S. Patent Application Serial No. filed
on the
same date as the present application, entitled "DRILL BIT GAUGE PAD CONTROL"
(temporarily referenced by Attorney Docket No. 57.0831 U.S. CIP), which is
incorporated by
reference in its entirety for all purposes.
[0003] This application is related to U.S. Patent Application Serial No. /,,
filed on the
same date as the present application, entitled "SYSTEM AND METHOD FOR
DIRECTIONALLY DRILLING A BOREHOLE WITH A ROTARY DRILLING SYSTEM"
(temporarily referenced by Attorney Docket No. 57.0834 U.S. CIP), which is
incorporated by
reference in its entirety for all purposes.
[0004] This application is related to U.S. Patent Application Serial No. /,,
filed on the
same date as the present application, entitled "METHOD AND SYSTEM FOR STEERING
A DIRECTIONAL DRILLING SYSTEM" (temporarily referenced by Attorney Docket No.
57.0853 U.S. CIP), which is incorporated by reference in its entirety for all
purposes.
BACKGROUND
[0005] This disclosure relates in general to drilling a borehole and, but not
by way of
limitation, to controlling direction of drilling for the borehole.
[0006] In many industries, it is often desirable to directionally drill a
borehole through an
earth formation or core a hole in sub-surface formations in order that the
borehole and/or
coring may circumvent and/or pass through deposits and/or reservoirs in the
formation to
reach a predefined objective in the formation and/or the like. When drilling
or coring holes
in sub-surface formations, it is sometimes desirable to be able to vary and
control the
direction of drilling, for example to direct the borehole towards a desired
target, or control the
direction horizontally within an area containing hydrocarbons once the target
has been
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reached. It may also be desirable to correct for deviations from the desired
direction when
drilling a straight hole, or to control the direction of the hole to avoid
obstacles.
[0007] In the hydrocarbon industry for example, a borehole may be drilled so
as to
intercept a particular subterranean-formation at a particular location. In
some drilling
processes, to drill the desired borehole, a drilling trajectory through the
earth formation may
be pre-planned and the drilling system may be controlled to conform to the
trajectory. In
other processes, or in combination with the previous process, an objective for
the borehole
may be determined and the progress of the borehole being drilled in the earth
formation may
be monitored during the drilling process and steps may be taken to ensure the
borehole attains
the target objective. Furthermore, operation of the drill system may be
controlled to provide
for economic drilling, which may comprise drilling so as to bore through the
earth formation
as quickly as possible, drilling so as to reduce bit wear, drilling so as to
achieve optimal
drilling through the earth formation and optimal bit wear and/or the like.
[0008] One aspect of drilling is called "directional drilling." Directional
drilling is the
intentional deviation of the borehole/wellbore from the path it would
naturally take. In other
words, directional drilling is the steering of the drill string so that it
travels in a desired
direction.
[0009) Directional drilling is advantageous in offshore drilling because it
enables many
wells to be drilled from a single platform. Directional drilling also enables
horizontal drilling
through a reservoir. Horizontal drilling enables a longer length of the
wellbore to traverse the
reservoir, which increases the production rate from the well.
[0010] A directional drilling system may also be used in vertical drilling
operation as well.
Often the drill bit will veer off of a planned drilling trajectory because of
the unpredictable
nature of the formations being penetrated or the varying forces that the drill
bit experiences.
When such a deviation occurs, a directional drilling system may be used to put
the drill bit
back on course.
[00111 The monitoring process for directional drilling of the borehole may
include
determining the location of the drill bit in the earth formation, determining
an orientation of
the drill bit in the earth formation, determining a weight-on-bit of the
drilling system,
determining a speed of drilling through the earth formation, determining
properties of the
earth formation being drilled, determining properties of a subterranean
formation surrounding
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the drill bit, looking forward to ascertain properties of formations ahead of
the drill bit,
seismic analysis of the earth formation, determining properties of reservoirs
etc. proximal to
the drill bit, measuring pressure, temperature and/or the like in the borehole
and/or
surrounding the borehole and/or the like. In any process for directional
drilling of a borehole,
whether following a pre-planned trajectory, monitoring the drilling process
and/or the drilling
conditions and/or the like, it is necessary to be able to steer the drilling
system.
[0012] Forces which act on the drill bit during a drilling operation include
gravity, torque
developed by the bit, the end load applied to the bit, and the bending moment
from the drill
assembly. These forces together with the type of strata being drilled and the
inclination of the
strata to the bore hole may create a complex interactive system of forces
during the drilling
process.
[0013] The drilling system may comprise a"rotary drilling" system in which a
downhole
assembly, including a drill bit, is connected to a drill-string that may be
driven/rotated from
the drilling platform. In a rotary drilling system directional drilling of the
borehole may be
provided by varying factors such as weight-on-bit, the rotation speed, etc.
[0014] With regards to rotary drilling, known methods of directional drilling
include the
use of a rotary steerable system (RSS). In an RSS, the drill string is rotated
from the surface,
and downhole devices cause the drill bit to drill in the desired direction.
Rotating the drill
string greatly reduces the occurrences of the drill string getting hung up or
stuck during
drilling.
[0015] Rotary steerable drilling systems for drilling deviated boreholes into
the earth may
be generally classified as either "point-the-bit" systems or "push-the-bit"
systems. In the
point-the-bit system, the axis of rotation of the drill bit is deviated from
the local axis of the
bottomhole assembly ("BHA") in the general direction of the new hole. The hole
is
propagated in accordance with the customary three-point geometry defined by
upper and
lower stabilizer touch points and the drill bit. The angle of deviation of the
drill bit axis
coupled with a finite distance between the drill bit and lower stabilizer
results in the non-
collinear condition required for a curve to be generated. There are many ways
in which this
may be achieved including a fixed bend at a point in the bottomhole assembly
close to the
lower stabilizer or a flexure of the drill bit drive shaft distributed between
the upper and
lower stabilizer.
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[0016] Pointing the bit may comprise using a downhole motor to rotate the
drill bit, the
motor and drill bit being mounted upon a drill string that includes an angled
bend. In such a
system, the drill bit may be coupled to the motor by a hinge-type or tilted
mechanism/joint, a
bent sub or the like, wherein the drill bit may be inclined relative to the
motor. When
variation of the direction of drilling is required, the rotation of the drill-
string may be stopped
and the bit may be positioned in the borehole, using the downhole motor, in
the required
direction and rotation of the drill bit may start the drilling in the desired
direction. In such an
arrangement, the direction of drilling is dependent upon the angular position
of the drill
string.
[0017] In its idealized form, in a pointing the bit system, the drill bit is
not required to cut
sideways because the bit axis is continually rotated in the direction of the
curved hole.
Examples of point-the-bit type rotary steerable systems, and how they operate
are described
in U.S. Patent Application Publication Nos. 2002/0011359; 2001/0052428 and
U.S. Patent
Nos. 6,394,193; 6,364,034; 6,244,361; 6,158,529; 6,092,610; and 5,113,953 all
herein
incorporated by reference.
[0018] Push the bit systems and methods make use of application of force
against the
borehole wall to bend the drill-string and/or force the drill bit to drill in
a preferred direction.
In a push-the-bit rotary steerable system, the requisite non-collinear
condition is achieved by
causing a mechanism to apply a force or create displacement in a direction
that is
preferentially orientated with respect to the direction of hole propagation.
There are many
ways in which this may be achieved, including non-rotating (with respect to
the hole),
displacement based approaches and eccentric actuators that apply force to the
drill bit in the
desired steering direction. Again, steering is achieved by creating non co-
linearity between
the drill bit and at least two other touch points. In its idealized form the
drill bit is required to
cut side ways in order to generate a curved hole. Examples of push-the-bit
type rotary
steerable systems, and how they operate are described in U.S. Patent Nos.
5,265,682;
5,553,678; 5,803,185; 6,089,332; 5,695,015; 5,685,379; 5,706,905; 5,553,679;
5,673,763;
5,520,255; 5,603,385; 5,582,259; 5,778,992; 5,971,085 all herein incorporated
by reference.
[0019] Known forms of RSS are provided with a"counter rotating" mechanism
which
rotates in the opposite direction of the drill string rotation. Typically, the
counter rotation
occurs at the same speed as the drill string rotation so that the counter
rotating section
maintains the same angular position relative to the inside of the borehole.
Because the
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counter rotating section does not rotate with respect to the borehole, it is
often called
"geostationary" by those skilled in the art. In this disclosure, no
distinction is made between
the terms "counter rotating" and "geo-stationary."
[0020] A push-the-bit system typically uses either an internal or an external
counter-
rotation stabilizer. The counter-rotation stabilizer remains at a fixed angle
(or geo-stationary)
with respect to the borehole wall. When the borehole is to be deviated, an
actuator presses a
pad against the borehole wall in the opposite direction from the desired
deviation. The result
is that the drill bit is pushed in the desired direction.
[0021] The force generated by the actuators/pads is balanced by the force to
bend the
bottomhole assembly, and the force is reacted through the actuators/pads on
the opposite side
of the bottomhole assembly and the reaction force acts on the cutters of the
drill bit, thus
steering the hole. In some situations, the force from the pads/actuators may
be large enough
to erode the formation where the system is applied.
[0022] For example, the SchlumbergerTM PowerdriveTM system uses three pads
arranged
around a section of the bottomhole assembly to be synchronously deployed from
the
bottomhole assembly to push the bit in a direction and steer the borehole
being drilled. In the
system, the pads are mounted close, in a range of 1- 4 ft behind the bit and
are
powered/actuated by a stream of mud taken from the circulation fluid. In other
systems, the
weight-on-bit provided by the drilling system or a wedge or the like may be
used to orient the
drilling system in the borehole.
[0023] While system and methods for applying a force against the borehole wall
and using
reaction forces to push the drill bit in a certain direction or displacement
of the bit to drill in a
desired direction may be used with drilling systems including a rotary
drilling system, the
systems and methods may have disadvantages. For example such systems and
methods may
require application of large forces on the borehole wall to bend the drill-
string and/or orient
the drill bit in the borehole; such forces may be of the order of 5 kN or
more, that may require
large/complicated downhole motors or the like to be generated. Additionally,
many systems
and methods may use repeatedly thrusting of pads/actuator outwards into the
borehole wall as
the bottomhole assembly rotates to generate the reaction forces to push the
drill bit, which
may require complex/expensive/high maintenance synchronizing systems, complex
control
systems and/or the like.
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[0024] The drill bit is known to "dance" or clatter around in a borehole in an
unpredictable
or even random manner. This stochastic movement is generally non-deterministic
in that a
current state does not fully determine its next state. Point-the-bit and push-
the-bit techniques
are used to force a drill bit into a particular direction and overcome the
tendency for the drill
bit to clatter. These techniques ignore the stochastic dance a drill bit is
likely to make in the
absence of directed force.
SUMMARY
100251 In an embodiment, the present disclosure provides for a drill bit
direction system
that modifies or biases stochastic or natural movement of the drill bit and/or
stochastic
reaction forces between the drill bit and/or gauge pads and an inner-wall of
the borehole
being drilled to change a direction of drilling. The change of direction of
drilling may in
certain aspects be achieved with less effort, less complex surface/downhole
machinery and/or
more economically than with conventional steering mechanisms. The direction of
the drill bit
relative to the earth (or some other fixed point) is monitored to determine if
the direction
happens to align in some way with a preferred direction. If the direction
isn't close enough to
a preferred direction, a biasing mechanism emphasizes components of radial
motion to move
the direction closer to the preferred direction. Any of a number of biasing
mechanisms can
be used. Some embodiments can resort to conventional steering mechanisms to
supplement
or as an alternative to the biasing mechanism.
[0026] In another embodiment, a method for biasing erratic motion of a drill
bit to
directionally cause the drill bit to drill in a predetermined direction
relative to the earth is
disclosed. In one step, a direction of the drill bit relative to the earth is
determined. The
direction is compared with the predetermined direction. A biasing mechanism is
oriented to
emphasize components of radial motion of the drill bit in the predetermined
direction. The
biasing mechanism is activated when the comparing step determines the
direction is not
adequately aligned with the predetermined direction.
[0027] In yet another embodiment, a drill bit direction system for biasing
erratic motion of
a drill bit to directionally cause a drill bit to drill in a predetermined
direction relative to the
earth is disclosed. The drill bit direction system includes a biasing
mechanism, a direction
sensor and a controller. The biasing mechanism emphasizes components of radial
motion of
the drill bit in the predetermined direction of the drill bit relative to the
earth. The direction
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sensor determines a direction of the drill bit downhole. The controller
compares a
predetermined direction with the direction. The biasing mechanism is activated
when the
direction deviates from the predetermined direction.
[0028] Further areas of applicability of the present disclosure will become
apparent from
the detailed description provided hereinafter. It should be understood that
the detailed
description and specific examples, while indicating various embodiments, are
intended for
purposes of illustration only and are not intended to necessarily limit the
scope of the
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present disclosure is described in conjunction with the appended
figures:
FIG. 1 depicts a block diagram of an embodiment of a drill bit direction
system;
FIGs. 2A and 2C illustrate flowcharts of embodiments of a process for
controlling drill bit direction; and
FIGs. 3A and 3C illustrate a state machine for managing the drill bit
direction
system.
[0030] In the appended figures, similar components and/or features may have
the same
reference label. Further, various components of the same type may be
distinguished by
following the reference label by a dash and a second label that distinguishes
among the
similar components. If only the first reference label is used in the
specification, the
description is applicable to any one of the similar components having the same
first reference
label irrespective of the second reference label.
DETAILED DESCRIPTION
[0031] The ensuing description provides preferred exemplary embodiment(s)
only, and is
not intended to limit the scope, applicability or configuration of the
disclosure. Rather, the
ensuing description of the preferred exemplary embodiment(s) will provide
those skilled in
the art with an enabling description for implementing a preferred exemplary
embodiment. It
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being understood that various changes may be made in the function and
arrangement of
elements without departing from the spirit and scope as set forth in the
appended claims.
[0032] Referring first to FIG. 1, a block diagram of an embodiment of a drill
bit direction
system 100 is shown. An integrated control and information service (ICIS) 104
is located
above ground to manage the drillstring rotation control block 112 and the
drawworks control
block 108. Additionally, the ICIS 104 generally guides the direction of
drilling in the earth
formation. Information is communicated downhole to a bottomhole assembly (BHA)
120
such as a desired orientation or direction to achieve for the drill bit and
possibly selection of
various biasing and steering mechanisms 132, 136 to use. The direction is
defined relative to
any fixed point such as the earth. The information may additionally provide
control
information for the BHA 120 and any biasing and steering mechanisms 132, 136.
[0030] The ICIS 104 manages the drillstring rotation control block 112 and the
drawworks
control block 108. The phase, torque and speed of rotation of the drillstring
is monitored and
managed by the drillstring control block 112. Information from the BHA 120 can
be
analyzed by the ICIS 104 as feedback on how the management is being performed
by the
drillstring control block 112. Various operations during drilling use the
drawworks control
block 108, for example, removal of the drillstring. The ICIS 104 manages
operation of the
drawworks control block 108 during these operations.
[0033] The BHA 120 includes a downhole controller 124, an orientation or
direction sensor
128, a bit rotation sensor 140, one or more biasing mechanism 132, and one or
more steering
mechanisms 136. A typical BHA may have more control systems, which are not
shown in
FIG. 1. Information is communicated to the BHA 120 from the surface to
indicate a
preferred direction of the drill bit. Additionally, use of biasing and
steering mechanisms 132,
136 can be generally controlled by the ICIS 104, but the downhole controller
124 controls
real-time operation of the biasing and steering mechanisms 132, 136 with
information
gathered from the direction and bit rotation sensors 128, 140.
[0034] Information is communicated from the BHA 120 back to the ICIS 104 at
the
surface. The direction of the drill bit observed may be periodically
communicated along with
use of various biasing and steering mechanisms 132, 136. A borehole path
information
database 116 stores the information gathered downhole to know how the borehole
navigates
through the formation. The ICIS 104 can recalculate the best orientation or
direction to use
for the drill bit and communicate that to the BHA 120 to override the prior
instructions.
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Additionally, the effectiveness of the various biasing and steering mechanisms
132, 136 can
be analyzed with other information gathered on the formation to provide
guidance downhole
on how to best use the available biasing and steering mechanisms 132, 136 to
achieve the
geometry of the borehole desired for a particular drill site.
[0035] The direction sensor 128 can determine the current direction of the
drill bit with
respect to a particular frame of reference in three dimensions (i.e., relative
to the earth or
some other fixed point). Various techniques can be used to determine the
current direction,
for example, an inertially or roll-stabilized platform with gyros can be
compared to references
on the drill bit, accelerometers could be used to track direction and/or
magnetometers could
measure direction relative to the earth's magnetic field. Measurements could
be noisy, but a
filter could be used to average out the noise from measurements.
[0036] The bit rotation sensor 140 allows monitoring the phase of rotation for
the drill bit.
The downhole controller 124 takes the sensor information to allow synchronized
control of
the biasing mechanism(s) 132. With knowledge of the phase, the biasing can be
performed
every rotation cycle or any integer fraction of the cycles (e.g., every other
rotation, every
third rotation, every fourth rotation, every tenth rotation, etc.). Other
embodiments do not
use a bit rotation sensor 140 or synchronized manipulation of the biasing
mechanism(s) 132.
[00371 There are various steering mechanisms 136 that persistently enforce
drill bit
movement. Steering mechanisms 136 do not intentionally take advantage of the
stochastic
movement of the drill bit that naturally occurs. A given site may use one or
more of these
steering mechanisms 136 to create a borehole that changes direction as desired
through the
formation. Different types of steering mechanisms 136 include bent arms, lever
arms
synchronized with rotation, universal joints, and geostationary mechanisms
that exert force in
a particular direction. These steering mechanisms can predictably direct the
drill bit, but do
not take advantage stochastic movement of the drill bit that could be in the
correct direction
anyway. Other embodiments may forgo steering mechanisms 136 completely by
reliance on
biasing mechanisms 132 for directional drilling.
[0038] A biasing mechanism 132 can be used before resort to a steering
mechanism 136.
The biasing mechanism 132 selects or emphasizes those components of the radial
motion of
the drill bit in a chosen direction. Directional control is achieved by
holding the orientation
of the biasing mechanism 132 broadly fixed in the chosen direction. Some
embodiments may
only have one or more biasing mechanisms 132 downhole without any steering
mechanisms
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136. Biasing mechanisms 132 take advantage of the tendency for the drill bit
to move around
in the bore hole by only activating when the stochastic movement goes in the
wrong
direction. For example, gage pads or cutters can be moved, a gage ring can
exert pressure
and/or jetting can be used in various embodiments as the biasing mechanism
132. Any
asymmetry and can be manipulated is usable as a biasing mechanism 132. In some
cases, the
drill bit is designed and manufactured so as to exert a side force in a
particular azimuthal
direction relative to the drill bit. The biasing mechanism 132 is activated to
bias the side
force. Such a side force rotates with the drill bit to emphasize cutting in
the chosen direction.
The biasing mechanism 132 can be synchronized to activate and deactivate with
rotation of
the drill bit.
[0039] The downhole controller 124 uses the information sent from the ICIS 104
along
with the direction and bit rotation sensors 128, 140 to actively manage the
use of biasing and
steering mechanisms 132, 136. The desired direction of the drill bit along
with guidelines for
using various biasing and steering mechanisms 132, 136 is communicated from
the ICIS 104.
The downhole controller 124 can use fuzzy logic, neural algorithms, expert
system
algorithms to decide how and when to influence the drill bit direction in
various
embodiments. Generally, the speed of communication between the BHA 120 and the
ICIS
104 does not allow real-time control from the surface in this embodiment, but
other
embodiments could allow for surface control in real-time. The stochastic
direction of the
drill bit can be adaptively used in a less rigid manner. For example, if a
future turn in the
borehole is desired and the drill bit is making the turn prematurely, the turn
can be accepted
and the future plan revised.
[0040] With reference to FIG. 2A, a flowchart of an embodiment of a process
200-1 for
controlling drill bit direction is shown. This embodiment only uses a single
biasing
mechanism 136 to control the direction of the drill bit. The depicted portion
of the process
beings in block 204 where an analysis of the formation and end point is
performed to plan the
borehole geometry. The ICIS 104 manipulates the drillstring, drawworks and
other systems
in block 208 to create the borehole according to the plan. A desired direction
of the drill bit
is determined in block 212 and communicated to the downhole controller 124 in
block 216.
The desired direction could be a single goal or a range of acceptable
directions.
[0041] The desired direction along with any biasing selection criteria is
received by the
downhole controller 124 in block 220. The current pointing of the drill bit is
determined by
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the direction sensor 128 in block 224. It is determined in block 228 if the
direction is
acceptable based upon the instructions from ICIS 104. This embodiment allows
some
flexibility in the direction and re-determines the plan based upon the
stochastic movement
allowed to occur. An acceptable direction is one that allows achieving the end
point with the
drill bit if the plan were revised. A certain plan may have predetermined
deviations or ranges
of direction that are acceptable, but still avoid parts of the formation that
are not desired to
pass through.
[0042] Where the direction is not acceptable, processing goes from block 228
to block 236
where the biasing mechanism 132 is activated. The biasing mechanism 132 could
be
activated once or for a period of time. Alternatively, the biasing mechanism
132 could be
activated periodically in synchronization with the rotation of the drill bit.
The biasing
mechanism 132 selects or emphasizes those components of the radial motion of
the drill bit
that occur in the desired direction(s).
[0043] Where the direction is acceptable as determined in block 228,
processing continues
to block 240. The biasing mechanism 132 achieves directional control by
holding the
direction in the desired direction(s). Where un-needed because the erratic
motion of the drill
bit is already in the desired direction(s), the biasing mechanism 132 is not
activated. In block
240, the current direction is communicated by the downhole controller 124 to
the ICIS 104.
After reporting, processing loops back to block 212 for further management of
the direction
based upon any new instruction from the surface.
[0044] Referring next to FIG. 2B, a flowchart of another embodiment of the
process 200-2
for controlling drill bit direction is shown. This embodiment has multiple
biasing
mechanisms 132 available and can fall back onto a steering mechanism 136 if
the biasing
mechanism(s) 132 is not effective. The blocks up to block 228 are generally
performed the
same as the embodiment in FIG. 2A. Where the direction is not acceptable in
block 228,
processing continues to block 232 where a selection is made from at least two
biasing
mechanisms 232. Guidance from the ICIS 104 may dictate or influence the
decision on those
biasing mechanisms 132 to select and in what manner they should be controlled.
The
selected biasing mechanism 132 is used in step 236.
[0045] After using the biasing mechanism 132, the current direction is
reported to the ICIS
104 in block 240. If the biasing mechanism 132 or some other alternative is
still believed to
be effective in orienting the drill bit in block 244, processing loops back to
block 212 to
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continue using that biasing mechanism 132 or some other biasing mechanism 132
that might
influence those components of the radial motion of the drill bit to exert a
side force in a
particular azimuthal direction as desired. Where biasing mechanisms 132 are
determined to
be no longer effective in block 244, processing continues to block 248 to
activate the steering
mechanism 136, if any.
[0046] With reference to FIG. 2C, a flowchart of yet another embodiment of the
process
200-3 for controlling drill bit direction is shown. This embodiment is similar
to that of FIG.
2A except that multiple biasing mechanisms 132 can be chosen from in block
232. This
embodiment only relies upon biasing mechanisms 132 without resort to steering
mechanisms
136.
[0047] Referring next to FIG. 3A, an embodiment of a state machine 300-1 for
managing
the drill bit direction system 100 is shown. This control system moves between
two states
based upon a determination in state 304 if the drill bit is not in alignment
with a desired
direction or range of directions. This embodiment corresponds to the
embodiment of FIG.
2A. Where there is disorientation beyond an acceptable deviation, the drill
bit direction
system 100 goes from state 304 to state 308. In state 308, one or more of the
biasing
mechanisms are tried 132. In some cases, the same biasing mechanism 132 is
tried with
different parameters. For example, a gage pad can be moved at one phase in the
bit rotation
cycle, but later another phase is tried with the same or a different movement
of the gage pad.
[0048] With reference to FIG. 3B, another embodiment of the state machine 300-
2 for
managing the drill bit direction system 100 is shown. This embodiment has four
states and
generally corresponds to the embodiment of FIG. 2B. After attempting a biasing
mechanisml32 in state 308, a determination in state 312 is used to see if the
biasing
mechanism 132 was effective. Where the biasing mechanism 132 works adequately,
the
system returns to state 304. If the biasing mechanism 132 is not effective the
drill bit
direction system 100 goes from state 312 to state 316 where an active steering
mechanism
136 is used before returning to state 304.
[0049] Referring next to FIG. 3C, yet another embodiment of the state machine
300-3 for
managing the drill bit direction system 100 is shown. This embodiment has a
number of
biasing techniques and generally corresponds to the process 200-3 of FIG. 2C.
Where
disorientation is found in state 304, a biasing mechanism or technique is
chosen in state 312.
In the alternative, a number of biasing techniques can be chosen from state
312. The chosen
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biasing technique is performed in the chosen biasing state 320 before
returning to state 304
for further analysis of any disorientation.
[0050] A number of variations and modifications of the disclosed embodiments
can also be
used. For example, the invention can be used on drilling boreholes or cores.
The control of
the biasing process is split between the ICIS and the BHA in the above
embodiments. In
other embodiments, all of the control can be in either location.
[0051] Specific details are given in the above description to provide a
thorough
understanding of the embodiments. However, it is understood that the
embodiments may be
practiced without these specific details. For example, circuits may be shown
in block
diagrams in order not to obscure the embodiments in unnecessary detail. In
other instances,
well-known circuits, processes, algorithms, structures, and techniques may be
shown without
unnecessary detail in order to avoid obscuring the embodiments.
[0052] Implementation of the techniques, blocks, steps and means described
above may be
done in various ways. For example, these techniques, blocks, steps and means
may be
implemented in hardware, software, or a combination thereof. For a hardware
implementation, the processing units may be implemented within one or more
application
specific integrated circuits (ASICs), digital signal processors (DSPs),
digital signal
processing devices (DSPDs), programmable logic devices (PLDs), field
programmable gate
arrays (FPGAs), processors, controllers, micro-controllers, microprocessors,
other electronic
units designed to perform the functions described above, and/or a combination
thereof.
[0053] Also, it is noted that the embodiments may be described as a process
which is
depicted as a flowchart, a flow diagram, a data flow diagram, a structure
diagram, or a block
diagram. Although a flowchart may describe the operations as a sequential
process, many of
the operations can be performed in parallel or concurrently. In addition, the
order of the
operations may be re-arranged. A process is terminated when its operations are
completed,
but could have additional steps not included in the figure. A process may
correspond to a
method, a function, a procedure, a subroutine, a subprogram, etc. When a
process
corresponds to a function, its termination corresponds to a return of the
function to the calling
function or the main function.
[0054] Furthermore, embodiments may be implemented by hardware, software,
scripting
languages, firmware, middleware, microcode, hardware description languages,
and/or any
combination thereof. When implemented in software, firmware, middleware,
scripting
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language, and/or microcode, the program code or code segments to perform the
necessary
tasks may be stored in a machine readable medium such as a storage medium.
A.code
segment or machine-executable instruction may represent a procedure, a
function, a
subprogram, a program, a routine, a subroutine, a module, a software package,
a script, a
class, or any combination of instructions, data structures, and/or program
statements. A code
segment may be coupled to another code segment or a hardware circuit by
passing and/or
receiving information, data, arguments, parameters, and/or memory contents.
Information,
arguments, parameters, data, etc. may be passed, forwarded, or transmitted via
any suitable
means including memory sharing, message passing, token passing, network
transmission, etc.
[0055] For a firmware and/or software implementation, the methodologies may be
implemented with modules (e.g., procedures, functions, and so on) that perform
the functions
described herein. Any machine-readable medium tangibly embodying instructions
may be
used in implementing the methodologies described herein. For example, software
codes may
be stored in a memory. Memory may be implemented within the processor or
external to the
processor. As used herein the term "memory" refers to any type of long term,
short term,
volatile, nonvolatile, or other storage medium and is not to be limited to any
particular type of
memory or number of memories, or type of media upon which memory is stored.
[0056] Moreover, as disclosed herein, the term "storage medium" may represent
one or
more memories for storing data, including read only memory (ROM), random
access memory
(RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical
storage
mediums, flash memory devices and/or other machine readable mediums for
storing
information. The term "machine-readable medium" includes, but is not limited
to portable or
fixed storage devices, optical storage devices, wireless channels, and/or
various other storage
mediums capable of storing that contain or carry instruction(s) and/or data.
[0057] While the principles of the disclosure have been described above in
connection with
specific apparatuses and methods, it is to be clearly understood that this
description is made
only by way of example and not as limitation on the scope of the disclosure.
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