Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Apparatus For Controlling A Downhole Drilling Motor
Assembly
FIELD OF THE INVENTION
The present invention relates to an apparatus for
controlling a downhole drilling motor assembly
BACKGROUND OF THE INVENTION
A downhole drilling motor assembly always includes a
downhole drilling motor and may include other components, as
will hereinafter be further described. Regardless of the
components included in the assembly, the downhole drilling
motor is always subject to reactive torque. The amount of
reactive torque experienced varies with the type of formation
that is encountered when drilling. Sand provides a relatively
low amount of reactive torque. A rock formation provides a
relatively high amount of reactive torque. Passing from zones
of relatively low reactive torque to relatively high reactive
torque or vis-a-versa tends to be hard on the downhole
drilling motor assembly.
SL1~ARY OF THE INVENTION
What is required is an apparatus for controlling a
downhole drilling motor assembly which has among its features
a capability of reducing the damaging effects of variations in
reactive torque.
According to the present invention there is provided an
apparatus for controlling a downhole drilling motor assembly,
which includes a tubular housing having an interior sidewall
which defines an interior bore. A mandrel is rotatably
mounted within the interior bore of the housing. The mandrel
has an exterior surface. A hydraulic dampener assembly is
disposed between the interior sidewall of the housing and the
exterior surface of the mandrel. The hydraulic dampener
assembly limits the rate of rotation of the mandrel within the
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housing, thereby providing a preset resistance to reactive
torque.
The apparatus, as described above, uses hydraulics to
limit the rate of rotation of the mandrel within the housing.
This protects the downhole drilling motor assembly from
variations in reactive torque. It can also be used to adjust
the drilling speed of the downhole drilling motor assembly.
This is done by permitting a selected amount of reactive
torque. If the drilling speed is to be decreased in order to
prolong the life of the drill bit, the amount of reactive
torque permitted by the apparatus is increased. If the
drilling speed is to be increased, the amount of reactive
torque permitted by the apparatus is decreased. Adjustments
are made to the reactive torque permitted by the apparatus by
altering the viscosity of the hydraulic fluid used. The more
viscose the hydraulic fluid, the more slowly the hydraulic
fluid will flow through the hydraulic dampener to enable the
mandrel to rotate. The less viscose the hydraulic fluid, the
more rapidly the hydraulic fluid will flow through the
hydraulic dampener to enable the mandrel to rotate.
Once the teachings of the present invention are
understood, there may be alternative configurations of
hydraulic dampener which could be developed by one skilled in
the art. The preferred form of hydraulic dampener which is
hereinafter illustrated and described includes an annular body
having a sidewall, a first end, a second end, an interior
surface and an exterior surface. A splined engagement is
provided between the interior surface of the annular body and
the exterior surface of the mandrel. This causes the annular
body to rotate with the mandrel while enabling limited axial
movement of the annular body along the mandrel. A guide track
is provided on the exterior surface which encircles the
annular body. The guide track alternatively extends in a
first direction from the first end toward the second end of
the annular body and then in a second direction from the
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second end toward the first end of the annular body in a zig-
zag pattern. Several guide members extend inwardly into the
interior bore from the interior surface of the housing. The
guide members engage the guide track on the annular body.
This limits rotational movement of the annular body relative
to the housing to the zig-zag pattern provided by the guide
track. It is preferred that the guide members terminate in
balls, as this reduces friction between the guide members and
the guide track.
The movement of the annular body is dampened by
hydraulics. At least one flow passage extends through the
annular body. The annular body is only being able to move as
hydraulic fluid is displaced via the flow passage. Movement
of the annular body in the first direction occurring at a rate
determined by the displacement of hydraulic fluid in the
second direction and movement of the annular body in the
second direction occurring at a rate determined by the
displacement of hydraulic fluid in the first direction. One
refinement is to use one way hydraulic valves. In accordance
with this embodiment, a first series of one way hydraulic
valves extend through the sidewall between first end and the
second end of the annular body. Hydraulic fluid can only pass
through the first series of one way hydraulic valves from the
second end to the first end, such that movement in the first
direction can only occur at a rate determined by the bleeding
of hydraulic fluid through the first series of one way
hydraulic valves. A second series of one way hydraulic valves
extend through the sidewall between the first end and the
second end of the annular body. Hydraulic fluid can only pass
through the second series of hydraulic valves from the first
end to the second end, such that movement in the second
direction can only occur at a rate determined by the bleeding
of hydraulic fluid through the second series of one way
hydraulic valves.
Although beneficial results may be obtained through the
use of the apparatus, as described above, further features may
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be desirable when the downhole drilling motor assembly
includes a bent housing and a sonde housing. A bent housing,
as the name implies, is a housing with a bend in it of between
one and two degrees which is added to the downhole drilling
motor assembly in order to permit a directional deviation to
be achieved. A sonde housing is an electronics package which
is added to the downhole drilling motor assembly to provide
information on drill bit positioning, including information as
to the positioning of the bend of the bent housing. when
drilling a straight hole with a downhole drilling motor
assembly, the bend of the bent housing is permitted to orbit
the axis of the hole. In order to turn the downhole drilling
motor assembly, the bend must be pointing in the direction the
driller wishes to go and be held stationary. Increasingly,
downhole drilling motor assemblies are being used with coil
tubing. Although the sonde housing gives the driller an
accurate indication of the positioning of the bend of the bent
housing, it is difficult for the driller to point the bend in
the desired direction and then maintain the bend in position
while drilling. Even more beneficial results may, therefore,
be obtained when means is provided to selectively block the
flow of hydraulic fluid simultaneously through both the first
series of one way hydraulic valves and the second series of
one way hydraulic valves, thereby locking the mandrel in a
selected rotational position relative to the housing. The
manner in which the locking of the mandrel in a selected
rotational position relative to the housing is effected may
vary. There will hereinafter be described and illustrated an
annular plug reciprocally movable along the mandrel between a
locking position engaging one of the first end or the second
end of the annular body and a release position spaced from the
annular body. The movement of the annular plug between the
locking position and the release position can be accomplished
through a telescopic actuator. It is envisaged that the
telescopic actuator will be powered by an electric motor which
is controlled by the driller through a wireline connection.
There will also be described an alternative embodiment in
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which an electrically activated valve communicating with the
flow passage through which hydraulic fluid passes is used to
selectively block flow. When the electrically activated valve
is in an open position it allows a flow of hydraulic fluid
5 through the flow passage. When the electrically activated
valve is in a closed position it stops the flow of hydraulic
fluid through the flow passage. Means is provided for
selectively moving the electrically activated valve between
the open position and the closed position.
Although beneficial results may be obtained through the
use of the apparatus for controlling a downhole drilling motor
assembly, as described above, it is preferred that the
electrically activated valve not be subject to movement with
the annular body. If a wire which makes an electrical
connection is subjected to constant movement, the wire tends
to fatigue. Even more beneficial results may, therefore, be
obtained when the electrically activated valve is mounted on a
stationary flow restricting member. This flow restricting
member is spaced from one of the first end or the second end
of the annular body and blocks the movement of hydraulic fluid
within the hydraulic chamber. The hydraulic fluid trapped
between the annular body and the flow restricting member
prevents movement of the annular body until the electrically
activated valve is in the open position. In this manner the
electrically activated valve can control flow through the
annular body, without moving with the annular body.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become
more apparent from the following description in which
reference is made to the appended drawings, the drawings are
for the purpose of illustration only and are not intended to
in any way limit the scope of the invention to the particular
embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation view, in section, of an
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apparatus for controlling a downhole drilling motor assembly
in accordance with the teachings of the present invention.
FIGURE 2 is a detailed side elevation view, in section,
of the apparatus illustrated in FIGURE 1.
FIGURE 3 is a detailed side elevation view, in section,
of the apparatus illustrated in FIGURE 1, with annular plug in
a locked position.
FIGURE 4 is a detailed side elevation view, in section of
the apparatus illustrated in FIGURE 1 with annular plug in a
release position.
FIGURE 5 is a perspective view an annular body with a
guide track.
FIGURE 6 is a side elevation view of a downhole drilling
motor assembly which includes a bent housing and a sonde
housing.
FIGURE 7 is a detailed side elevation view, in section,
of an alternative form of hydraulic dampener assembly, in a
locked position.
FIGURE 8 is a detailed side elevation view, in section,
of the alternative form of hydraulic dampener assembly
illustrated in FIGURE 7, in a release position.
FIGURE 9 is a perspective view an annular body with a
guide track, from the alternative form of hydraulic dampener
assembly illustrated in FIGURE 7.
FIGURE 10 is an end elevation view of a clutch which
engages an end of the annular body illustrated in FIGURE 9.
FIGURE 11 is a detailed side elevation view, in section,
of a second alternative form of hydraulic dampener assembly.
in with an electrically activated valve.
FIGURE 12 is a perspective view of an annular body with
several guide tracks, from the second alternative form of
hydraulic dampener assembly illustrated in FIGURE 11.
FIGURE 13 is a detailed side elevation view, in section,
of the second alternative form of hydraulic dampener assembly
illustrated in FIGURE 11, with an independent power source.
DETAILED DESCRIPTION OF THE PREFERRED E1~UDIMENT
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The preferred embodiment, an apparatus for controlling a
downhole drilling motor assembly generally identified by
reference numeral 10, will now be described with reference to
FIGURES 1 through 6.
Structure and Relationship of Parts:
Referring to FIGURE 1, apparatus 10 which includes a
tubular housing 12 with an interior sidewall 14 which defines
an interior bore 16. A mandrel 18 is rotatably mounted within
interior bore 16 of housing 12. Mandrel 18 has an exterior
surface 20. For ease of assembly, housing 12 has a first
section 22, a second section 24 and a third section 26 with
joints 28 provided between first section 22 and second section
24 and between second section 24 and third section 26. Grease
ports 25 are positioned along tubular housing 12, in order to
add oil, grease or other hydraulic fluids after assembly.
Referring to FIGURE 2. radial bearings 30 are disposed
between interior sidewall 14 of housing 12 and exterior
surface 20 of mandrel 18, thereby transmitting radial loads
from mandrel 18 to housing 12. Thrust bearings, generally
referenced by numeral 32, are disposed between interior
sidewall 14 of housing 12 and exterior surface 20 of mandrel
18, thereby transmitting axial thrust loads from mandrel 18 to
housing 12. Seals 34 are positioned in grooves 35 between
interior sidewall 14 of housing 12 and exterior surface 20 of
mandrel 18 to prevent the entry of abrasive drilling fluids
into radial bearings 30 and thrust bearings 32.
Referring to FIGURE 3 and 4, a hydraulic dampener
assembly, generally referenced by numeral 36, is disposed
between interior sidewall 14 of housing 12 and exterior
surface 20 of mandrel 18. Hydraulic dampener assembly 36
includes an annular body 38 that has a sidewall 40, a first
end 42, a second end 44, an interior surface 46 and an
exterior surface 48. There is a splined engagement 50 between
interior surface 46 of annular body 38 and exterior surface 20
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of mandrel 18, such that annular body 38 rotates with mandrel
18 while being capable of limited axial movement along mandrel
18. Seals 39 are positioned in grooves 41 along interior
surface 46 and exterior surface 48 of sidewall 40 of annular
body 38 to prevent fluids from bypassing hydraulic dampener
assembly 36.
Referring to FIGURE 5, exterior surface 48 of annular
body 30 has a guide track 52 which encircles annular body 38.
Guide track 52 alternatively extends in a first direction from
first end 42 toward second end 44 of annular body 38 and then
in a second direction from second end 44 toward first end 42
of annular body 38 in a zig-zag pattern 54.
Referring to FIGURE 3 and 4, several guide members 56
extend inwardly into interior bore 16 from interior sidewall
14 of housing 12. Guide members 56 engage with guide track 52
on annular body 38, thereby limiting rotational movement of
annular body 38 relative to housing 12 to zig-zag pattern 54
provided by guide track 52.
A first series of one way hydraulic valves 58 extend
through sidewall 40 between first end 42 and second end 44 of
annular body 38 through which hydraulic fluid can only pass
from second end 44 to first end 42, such that movement in the
first direction can only occur at a rate determined by the
bleeding of hydraulic fluid through first series of one way
hydraulic valves 58. First series of one way hydraulic valves
58 has a fluid inlet 60 and a fluid outlet 62. A spring 64
operates to bias a ball 66 into sealing engagement with fluid
inlet 60. Fluid enters inlet 60 by overcoming the biasing
force of spring 64 to move past ball 66. Fluid cannot,
however, exit inlet 60 as fluid pushes ball 66 into sealing
engagement with ball seat 67.
A second series of one way hydraulic valves 68 extends
through sidewall 40 between first end 42 and second end 44 of
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annular body 38 through which hydraulic fluid can only pass
from first end 42 to second end 44, such that movement in the
second direction can only occur at a rate determined by the
bleeding of hydraulic fluid through second series of one way
hydraulic valves 68. Second series of one way hydraulic valves
68 has a fluid inlet 70 and fluid outlet 72. A spring 74
operates to bias a ball 76 into sealing engagement with fluid
outlet 72. Fluid enters inlet 70 by overcoming the biasing
force of spring 74 to move past ball 76. Fluid cannot,
however, exit inlet 70 as fluid pushes ball 76 into sealing
engagement with ball seat 77.
An annular plug 78 is reciprocally movable along mandrel
18 between a locking position illustrated in FIGURE 3 and a
release position illustrated in FIGURE 4. Referring to FIGURE
3. in the locking position, annular plug 78 engages second end
44 of annular body 38 so that annular plug 78 blocks the flow
of hydraulic fluid simultaneously through both first series of
one way hydraulic valves 58 and second series of one way
hydraulic valves 68, thereby locking mandrel 18 in a selected
rotational position relative to housing 12. Referring to
FIGURE 4. in the release position, annular plug 78 is spaced
from annular body 38 whereby the flow of hydraulic fluid is
permitted through both first series of one way hydraulic
valves 58 and second series of one way hydraulic valve 68.
Referring to FIGURE 1, a telescopic actuator 80 is
disposed in housing 12. Telescopic actuator 80 is adapted to
selectively move annular plug 78 between the release position
and the locking position. Telescopic actuator 80 has an
internal electric motor. A wireline connection 82 for
selectively providing power to extend or retract telescopic
actuator 80 as desired by the driller operating controls on
surface. Referring to FIGURE 6, apparatus 10 is intended to
be connected to a downhole drilling motor assembly, generally
indicated by reference numeral 100 which includes has a
downhole motor 81, a sonde housing 82 and a bent housing 84.
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Bent housing has a bend 86 in it of between one and two
degrees.
Operation:
5 The use and operation of apparatus 10 a downhole drilling
motor assembly 100 will now be described with reference to
FIGURES 1 through 6.
Referring to FIGURE 1, apparatus 10, as described above,
10 uses hydraulic dampener assembly 36 to limit the rate of
rotation of mandrel 18 within housing 12, to provide a preset
resistance to reactive torque. Apparatus 10 can also be used
to adjust the drilling speed by permitting a selected amount
of reactive torque. If the drilling speed is to be decreased,
the amount of reactive torque permitted by apparatus 10 is
increased. If the drilling speed is to be increased, the
amount of reactive torque permitted by apparatus 10 is
decreased. All adjustments to reactive torque permitted by
apparatus 10 are arranged in advance by selecting the
viscosity of the hydraulic fluid used. The more viscose the
hydraulic fluid, the more slowly the hydraulic fluid will flow
through hydraulic dampener assembly 36 to enable mandrel 18 to
rotate. The less viscose the hydraulic fluid, the more
rapidly the hydraulic fluid will flow through hydraulic
dampener assembly 36 to enable mandrel 18 to rotate.
Referring to FIGURE 3 and 4, as hydraulic fluid flows
into first series of one way hydraulic valves 58 through fluid
inlet 60, the pressure of incoming hydraulic fluid pushes
against ball 66 to compresses spring 64, thereby moving ball
66 such that incoming hydraulic fluid can pass in through
fluid inlet 60 but can not exit back through fluid inlet 60 as
spring 64 biases ball 66 back against ball seat 67.
Similarly, as hydraulic fluid flow into second series of one
way hydraulic valves 68, the pressure of incoming hydraulic
fluid pushes against ball 76 to compresses spring 74, thereby
moving ball 76 such that incoming hydraulic fluid can pass in
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through fluid inlet 70 but can not exit back through fluid
inlet 70 as spring 74 biases ball 76 back against ball seat
77.
It will be appreciated from the foregoing description,
how apparatus 10 can be used to control reactive torque, as a
downhole drilling motor assembly drills through different
substrates. Apparatus 10 can also be used as a steering tool.
Referring to FIGURE 6, bend 86 in bent housing 84 permits a
directional deviation to be achieved, so that drilling
proceeds in the direction the driller wishes to go. Sonde
housing 82 provides vital drilling information, including
information as to the positioning of bend 86 of bent housing
84. When drilling in a straight line annular plug 78 is left
in the release position, illustrated in FIGURE 4. Mandrel 16
rotates at a rate of rotation permitted by hydraulic dampener
36 and bend 86 of bent housing 84 also moves in a rotary
fashion. When annular plug 78 is moved to the locked
position, illustrated in FIGURE 3, mandrel 16 no longer
rotates which means locks bent housing 84 with bend 86 in a
particular position. Referring to FIGURES 1 and 6. when bent
housing 84 is pointing in the desired direction, the driller
activates telescopic actuator 80 to move annular plug 78 to
the locking position to selectively block the flow of
hydraulic fluid simultaneously through both first series of
one way hydraulic valves 58 and second series of one way
hydraulic valves 68, thereby locking mandrel 18 in a selected
rotational position relative to housing 12 and bent housing 84
is maintained in position during drilling. By selectively
moving annular plug 78 between the locked and released
position, the driller is able to steer downhole drilling motor
assembly 100 via apparatus 10.
Variations:
Figures 7 through 13 have been included to demonstrate
variations that may be considered desirable. It would be
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undesirable if the guide members were to bind with the guide
track. The operation of the hydraulic dampener requires the
guide members to move along the guide track. Referring to
FIGURES 7 and 8, a variation is illustrated in which guide
members 56 terminate in balls 255, thereby reducing friction
between guide members 56 and guide track 52. Balls 255 engage
with guide track 52 on annular body 38, thereby limiting
rotational movement of annular body 38 relative to housing 12
to zig-zag pattern 54 provided by guide track 52.
There are various means for locking the mandrel in a
selected rotational position relative to the housing. One
such means that is viewed as viable is the use of a clutch.
Referring to FIGURES 7 through 10, there is illustrated the
use of a clutch 200 as a locking mechanism. Clutch 200 is
reciprocally movable along mandrel 18 between a locking
position engaging second end 44 of annular body 38 as
illustrated in FIGURE 7 and a release position spaced from
annular body 38, as illustrated in FIGURE 8. Referring to
FIGURES 9, second end 44 of annular body 38 has a peripheral
tooth profile 210. Referring to FIGURE 10, clutch 200 also
has peripheral tooth profile 212. Referring to FIGURE 7, in
the locking position, peripheral tooth profile 212 of clutch
200 engages peripheral tooth profile 210 at second end 44 of
annular body 38, thereby locking mandrel 18 in a selected
rotational position relative to housing 12. Referring to
FIGURE 8. in the release position, peripheral tooth profile
212 of clutch 200 is disengaged from peripheral tooth profile
210 at second end 44 of annular body 38, and clutch 200 is
spaced from annular body 38.
Referring to FIGURES 11 through 13, there is illustrated
a second alternative embodiment of an apparatus for
controlling a downhole drilling motor assembly, generally
referenced by numeral 300. Embodiment 300 differs from the
alternative embodiments described above, in manner with which
the locking of mandrel 18 in a selected rotational position
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relative to housing 12 is effected. Referring to FIGURE 11,
with second alternative embodiment 300, hydraulic dampener
assembly 36 includes a hydraulic chamber 310 between mandrel
18 and housing 12. Annular body 38 is disposed within
hydraulic chamber 310. A flow passage extends 312 through
annular body 38 and annular body 38 is only able to move as
hydraulic fluid is displaced via flow passage 312. Movement of
annular body 38 in the first direction occurs at a rate
determined by the displacement of hydraulic fluid in the
second direction and movement of the annular body in the
second direction occurs at a rate determined by the
displacement of hydraulic fluid in the first direction.
With embodiment 300, an electrically activated valve 314
is provided that controls either directly or indirectly the
flow of fluid through flow passage 312. Electrically
activated valve 314 serves to indirectly control the flow of
hydraulic fluid through flow passage 312, as will hereinafter
be further described. Electrically activated valve 314 is
movable between an open position allowing a flow of hydraulic
fluid through flow passage 312 and a closed position stopping
the flow of hydraulic fluid through flow passage 312.
Electrically activated 314 valve is mounted on a
stationary flow restricting member 316 that is spaced from
second end 44 of annular body 38 and blocks the movement of
hydraulic fluid within hydraulic chamber 310. Hydraulic
fluid is trapped between annular body 38 and flow restricting
member 316 preventing movement of annular body 38 until
electrically activated valve 314 is in the open position.
Power for selectively moving electrically activated valve
314 between the open position and the closed position can be
supplied by a cable 318 which runs from a power source located
at the surface. Referring to FIGURE 13, in the alternative,
electrically activated valve 314 can have its own source of
power provided by a power unit 320. Power unit 320 houses an
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electrical package 322 including an antenna 324 that is
mounted on power unit 320 for the purpose of receiving an
activation signal remotely. Power unit 320 can also house a
hydraulic cylinder 326 with a pressure sensitive switch 328
which activates in response to pump pressure.
Referring to FIGURE 11, electrically activated valve 314
is mounted on stationary flow restricting member 316 so that
electrically activated valve 314 will not be subjected to
movement with annular body 38. If a wire which makes an
electrical connection is subjected to constant movement, the
wire tends to fatigue. By mounting electrically activated
valve 314 on flow restricting member 316, electrically
activated valve 314 can control flow through annular body 38,
without moving with annular body 38.
Referring to FIGURE 12. another difference illustrated in
embodiment 300 is that annular body 38 has a plurality of
guide tracks 52. Referring to FIGURE 11, guide tracks 52 are
adapted to engage with guide members 56 that extending
inwardly into interior bore 16 from interior sidewall 14 of
housing 12, thereby limiting the rotational movement of
annular body 38 relative to housing 12 to zig-zag pattern 54
provided by guide tracks 52 illustrated in FIGURE 12.
Referring to FIGURE 11, in the illustrated embodiment 300,
eight guide members 56 are illustrated however 16 can be used.
Each of guide members 56 terminate in ball 255, thereby
reducing friction between guide members 56 and guide tracks
52.
In this patent document, the word "comprising" is used in
its non-limiting sense to mean that items following the word
are included, but items not specifically mentioned are not
excluded. A reference to an element by the indefinite article
"a" does not exclude the possibility that more than one of the
element is present, unless the context clearly requires that
there be one and only one of the elements.
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It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment
without departing from the spirit and scope of the invention
5 as hereinafter defined in the Claims.
