Note: Descriptions are shown in the official language in which they were submitted.
CA 02218259 1997-10-14
WO 97/30269 PCTlUS97/02334
MOTOR DRIVE ACTUATOR FOR DOWNHOLE FLOW CONTROL DEVICES
Background of the Invention:
Field of the Invention
The invention relates to regulating flow of any given fluid in a particular
zone ~p
into or out of the production tube. More particularly, the invention relates
to selective
actuation of a flow control device.
Prior Art
As one of skill in the art will readily recognize, flow control devices such
as the
sliding sleeve, commercially available from Baker Oil Tools, 6023 Navigation
Boulevard, Houston, Texas 77011, have been known to the industry and have been
depended upon thereby for a number of years. The tool is very effective but
does
. require that a shifting tool be run to open or close the sliding sleeve.
Running a shifting
tool is time consuming and incurs the characteristic six figure cost
associated with any
CA 02218259 2004-O1-26
-2-
tool run. Moreover, it is sometimes desired to change the positions of the
closing
sleeve or insert relative to the sleeve housing in metered increments thereby
enabling
a closer control over the flow device; doing the same through the employment
of a
shifting tool is extremely difficult. Several miles of wireline, coil tubing,
etc., to
move in order to actuate the tool makes small position changes nearly
impossible.
Due to advancements in downhole electronic actuators and sensors as well as
sophisticated decision making electronics which may be either at the surface
or
downhole such as that disclosed in U.S. Patent No. 5,732,776, improved control
apparati are more feasible.
Summary of the Invention:
The above-discussed and other drawbacks and deficiencies of the prior art are
overcome or alleviated by the electronic actuation mechanisms of the
invention. In
order to provide reliable and easily meterable flow control device movement,
thus
reliably regulating flow for any particular zone, a motor and lead screw
arrangement
or ball screw assembly are provided in several embodiments employing linear
actuation and a motor and gear arrangement are provided in another embodiment
wherein the sleeve actually rotates to the open or closed position as opposed
to
linearly sliding open or closed.
In the first lead screw embodiment, the lead screw is rotatably attached to
the
motor (or motors if desired for enhanced torque characteristics) and is
threaded to a
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-3-
sleeve attachment connected to an insert of an otherwise conventional sliding
sleeve via
a releasable member. The releasable member may be solely shear release or may
employ a dog system as well as shear components. Providing power in one
polarity to
the motor opens the sliding sleeve, reversing polarity closes the sleeve. In
the rotatable
sleeve embodiment, the motor is operably connected to a gear which drives the
rotatable sleeve through teeth (a large ring gear profile) on the sleeve
itself. A
shearable type release member is not necessary in this embodiment because the
threads
on the gear will essentially be longitudinally oriented such that the sleeve
and the gear
are naturally separable from one another. As one of skill in the art will
recognize
however, an arrangement is required to impart rotational movement to the
rotating
sleeve; this can be provided by dogs actuated by a pull or push on the
assembly. In
both embodiments meterability can be accomplished either by regulating time of
power
availability to the motor or by employing a specialized stepper motor wherein
the
counts of the motor are employed to determine the position of the sleeve.
Moreover,
I S metered operation is enhanced by employing at least one and preferably a
plurality of
position sensors to provide accurate information about the position of the
closing sleeve
to logic circuits either downhole or at the surface. Power may be provided
downhole in
the form of a battery array or a' capacitor arrangement or power may be
provided from a
surface location. In the event of a failure of the electrical system or motor
and gear
system, a wireline or coil tubing string may be run with a shifting tool to
conventionally activate the sleeve by utilizing shifting profiles. Where the
sleeve being
operated by the shifting tool is a conventional sliding sleeve, the operation
thereof is
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-4-
the same as in the prior art, however if the sleeve is of the rotational type,
provision is
made whereby the inner rotating sleeve will be separable from the outer sleeve
and the
outer sleeve will have a blank section therein so that the inner sleeve may
simply be
moved as if it were a sliding sleeve.
The invention provides greater downhole control by allowing metered
machinery and offers speedier execution of sleeve changes.
In another embodiment of the invention a ball screw assembly is employed to
provide significantly enhanced motion transfer efficiency. The embodiment
employs a
brushless annular motor and annular' magnet arrangement which allows stepwise
movement of the motor. The magnets are mounted on the O.D. of an inner tube
and
turn upon the impetus provided by energizing of the coils. Due to the
interaction _a _~
between profiles on the motor shaft and a tube sized ball nut, rotation of the
shaft
drives the ball nut. Ball bearings within the ball nut, ride in the tube sized
ball seat
which is connected via a shear out assembly to the sliding sleeve insert.
Since the ball
seat cannot turn with the ball nut due to a key attached to the ball seat and
captured in
a keyway to prevent such rotation, only linear movement of the ball seat is
allowed by
the system. Due to the extremely low friction generated by the ball screw
assembly,
efficiency of motion transfer is at about ninety percent. (In the preferred
embodiment
about a sixty-eight foot-pound motor generates about 10,000 pounds of linear
force).
The motor drive components are maintained in optimal condition by being bathed
in
dielectric fluid, pressure compensated by a series of cylinders and pistons. A
shear out
assembly is included in this configuration to allow conventional operation of
the tool in
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-5-
the event of an actuator failure.
In another embodiment of the invention a ball screw assembly is motor driven
to extend a relatively narrow diameter ball seat uphole or downhole depending
upon
the firing order of the windings in the stator, which is controlled by the
downhole
electronics and processor package. The ball seat is connected to a connecting
shaft
which is connected to a drive yoke. The drive yoke is connected via a shear
out
structure to the insert of an otherwise conventional sliding sleeve. By
powering the
motor, force may be transmitted to the sliding sleeve to either open or close
the same.
In the event of failure of the actuat'idn tool, the shear out structure is
released and
conventional shifting of the sleeve may be initiated.
In yet another embodiment of the invention a second lead screw concept is
employed wherein a drive sleeve is threaded on the O.D. thereof and a gear set
transmits rotational energy from a motor to a ring gear having LD. threads
mateable to
the lead screw drive sleeve threads. The drive sleeve is prevented from
rotational
movement by a key connected to a position sensor such as a linear
potentiometer.
While the drive sleeve is prevented from rotating the position sensor is moved
with the
key to provide an accurate representation of the degree of openness of the
sliding
sleeve attached to the actuation mechanism of the invention. An electronics
and
processor package is also provided to monitor and direct operation of the
tool.
Each of the latter three embodiments of the invention employ an identical
shear
out structure or member utilizing a plurality of dogs and a plurality of shear
screws.
The dogs provide for translation of the energy of movement from the actuator
assembly
CA 02218259 2004-O1-26
-6-
to the sliding sleeve without imparting shear stress to the shear screws. This
avoids
premature failure of the shear screws and increases longevity of the tool. In
the event
the actuation mechanisms of the invention fail, the shear out structure may be
shifted
uphole to release the dogs. Once the dogs have disengaged from the actuation
drive
mechanism, the tool of the invention allows conventional shifting of the
insert in the
sliding sleeve by employing a prior art shifting tool on shifting profiles.
In accordance with one aspect of the present invention there is provided an
actuator for a downhole tool comprising:
a driver;
a translator coupled to and driven by said driver;
a permanent downhole tool coupled to said driver such that impetus created by
said driver operates said downhole tool;
a downhole processor and power delivery system operably connected to said
driver to selectively operate said driver; and
at least one sensor in communication with said processor and said downhole
tool such that sensory information collected from said downhole tool is
transmitted to
said processor for evaluation.
In accordance with another aspect of the present invention there is provided
an
actuator for a downhole tool comprising:
a motor;
an eccentrically mounted ball screw assembly coupled to and driven by said
motor;
a downhole tool coupled to said motor such that impetus created by said motor
operates said downhole tool;
a downhole processor and power delivery system operably connected to said
motor to selectively operate said motor; and
at least one sensor in communication with said processor and said downhole
tool such that sensory information collected from said downhole tool is
transmitted to
said processor for evaluation.
CA 02218259 2004-O1-26
-6a-
In accordance with yet another aspect of the present invention there is
provided an actuator for a downhole tool comprising:
a motor having windings which are electrically energized in a selected order
to
rotate said motor in a desired direction;
an annular ball screw assembly coupled to and driven by said motor;
a downhole tool coupled to said motor such that impetus created by said motor
operates said downhole tool;
a downhole processor and power delivery system operably connected to said
motor to selectively operate said motor; and
at least one sensor in communication with said processor and said downhole
tool such that sensory information collected from said downhole tool is
transmitted to
said processor for evaluation.
Brief Description of the Drawings:
An embodiment of the present invention will now be described more fully
with reference to the accompanying drawings in which:
FIGURES 1-3 is a sequential cross section of the invention in a closed
position;
FIGURES 4-6 is a sequential cross section of the invention in an open
position;
FIGURE 7 is a chart of the electronic components for the example of the
invention in use;
FIGURE 8 is a longitudinal cross sectional view of the invention illustrating
the motor and gear arrangement for the rotational embodiment of the invention;
FIGURE 9 is a cross sectional view of the invention illustrating the
rotational
layout of the rotating sleeve;
CA 02218259 2004-O1-26
-6b-
FIGURE 10 is a longitudinal cross sectional view of the invention illustrating
the contingency open position;
FIGURE 11 is a longitudinal cross section view of the invention illustrating
the contingency closed position;
FIGURES 12-17 illustrate an extended view of a longitudinal cross section of
an annular ball screw assembly actuator of the invention;
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-7_
FIGURE 13A illustrates a transverse section through FIGURE 13 at section line
13A-13A;
FIGURE 13B illustrates a transverse section through FIGURE I3 at section line
13B-13B;
FIGURES i 8-22 illustrate an extended view of a longitudinal cross section of
an eccentric ball screw assembly actuator of the invention;
FIGURE 19A is a cross section view of FIGURE 19 taken along section lines
19A-I9A;
FIGURE 21A is a cross section view of FIGURE 21 taken along section lines
21 A-21A;
FIGURE 21B is a cross section view of FIGURE 21 taken along section lines _
~,.
21B-21B;
FIGURE 2I C is a cross section view of FIGURE 21 taken along section lines
21 C-21 C;
FIGURES 23-28 illustrate an extended view of an annular lead screw assembly
actuator of the invention;
FIGURE 29 is a schematic perspective illustration of the motor, gear train and
actuator sleeve of the embodiment of FIGURES 23-28;
FIGURE 25A is a plan view of the motor and gear train of the invention taken
along line 25A-25A;
FIGURE 25B is a cross section view of FIGURE 25A taken along section line
25B-25B;
CA 02218259 1997-10-14
WO 97!30269 PCT/US97/02334
_g_
FIGURE 25C is a cross section view of FIGURE 25A taken along section line
25C-25C;
FIGURE 25D is a cross section view of FIGURE 25A taken along section line
25D-25D;
FIGURE 25E is a cross section view of the invention of FIGURES 23-28 taken
along section line 25E-25E; and
FIGURE 30 is a radial section view of FIGURE 25E taken along section line
30-30.
Detailed Description of the Preferred Embodiments:
I O Referring to FIGURES 1-3 the invention is illustrated with the sliding
sleeve _ ~ ~ _ ,
control device in the closed position. Illustrated is a sliding sleeve
commercially
available from Baker OiI Tools, 6023 Navigation Road, Houston, Texas 77011. It
will
be understood, however, that the apparatus of the invention could easily be
modified to
actuate other flow control devices. For clarity, 11 indicates an opening in
closing
sleeve 10 and 13 indicates an opening in housing 15. When 11 and I3 are
aligned to
any degree the zone will produce. The closing sleeve (or insert) 10 of the
sliding
sleeve control device is attached by a release mechanism, preferably of a
shear type and
in the first embodiment may employ a shear ring 12 as illustrated, to sleeve
attachment
member 14. In the most preferred embodiment however, a separate shear out
assembly
is employed to take the load of the sleeve off the shear ring during movement
of the -
sleeve. This helps to prevent failure of the device which can otherwise be
caused by
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-9-
fatigue of the shear ring 12 from the movement load. The shear assembly is
illustrated in the embodiment of FIGURE I2 et. seq. but is also employable
with this
first embodiment the drawings of which do not include the shear out structure.
Sleeve
attachment member 14 includes a threaded throughbore 16 and pin thread 18. As
will
be appreciated, pin thread 18 is preferred for assembly purposes so that the
shear
release 12 may easily be retained by shear retainer 20 which includes box
thread 22
adapted to mate with pin thread 18 on sleeve attachment member 14.
Threaded throughbore 16 is adapted for threaded engagement with lead screw
24. Lead screw 24 is elongated and is rotatably attached to motor 28 through
coupling
I O 26. It will be appreciated that coupling 26 may be of any type sufficient
to rotatably
bind lead screw 24 to shaft 30 of gear box 32 through which motor 28 transmits
to~qu~.~~ .~
In preferred arrangements a resolver is also attached to the moving members of
the
invention to determine position of the sleeve. It should be understood that
motor 28
may actually be a plurality of electronic motors linked together in order to
increase
1 S total torque output. Reversing polarity of motor 28, thus turning lead
screw 24 in
opposite directions causes sleeve attachment 14 to move uphole or downhole
depending upon direction of screw 24 movement. The uphole or closed position
is
shown in FIGURES I-3 and the downhole or open position in FIGURES 4-6.
As will be appreciated by one of skill in the art, the motor enables either a
full
20 open/full close operation or a metered open/metered close operation. This
is
accomplished by activating the motor in the desired direction only until a
position
sensor indicates that the sleeve is at a particular position. This information
is
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
- -10-
transmitted to a logic circuit either downhole or at the surface and a
decision is made as
to whether or not the position of the closing sleeve is acceptable. Another
embodiment
employs a stepper motor so that activation thereof will only activate the
motor for a
stepped increment or a predetermined number of stepped increments. This
provides
excellent metered control over the sliding sleeve. With respect to the
position sensor,
one of skill in the art will recognize that any position sensor will be
effective.
Adding support to the motor 28 and gear box 32 in the preferred embodiment is
flange 34 through which gear shaft 30 extends. Flange 34 is fixedly connected
to
housing 35 of the invention. '
Motor 28 is powered and receives commands via power line 36 connected to
PCB 38 housed in atmospheric chamber 40. Energy is preferably provided to
PCB_38 _~p~
through TEC wire 42 from the surface or from a downhole battery or capacitor
power
source (not shown). In the event a capacitor source is desired, the preferred
amount of
energy stored would be enough to complete one whole cycle, from closed to open
to
~ closed.
1n the event of a failure of any of the electrical actuation components, the
sleeve
may be conventionally actuated using a shifting tool on shifting profiles 44
which are
known from the otherwise conventional sliding sleeve 46 commercially available
from
Baker Oil Tools, 6023 Navigation Boulevard, Houston, Texas 77011. Operating
the
sleeve conventionally merely requires placing a load in tension or compression
on the
shifting profiles sufficient to uncouple the shear release 12 to separate the
closing
sleeve 10 from the sleeve attachment member 14 or shearing and releasing dogs
as
CA 02218259 2004-O1-26
-11-
discussed hereinbelow. After release, the sliding sleeve operates in the
manner
heretofore common to the industry.
The employment of at least one position sensor is contemplated for the
invention in order to provide such information to the surface or to a downhole
intelligence package such as one of those disclosed in U.S. Patent No.
5,732,776. It
will be appreciated that the tools described herein are analogous to the
downhole
control devices referred to in the incorporated application. In connection
with a
downhole intelligence system the flow control device can be completely
operated
automatically downhole.
One preferred example of the tool of the invention with intelligent downhole
components is composed of the following interconnected modules.
A microprocessor based control module is used for the acquisition of
downhole information related to the location of the sleeve and status of the
electrical
motor used for the actuation of the sleeve. The module also interfaces with
the
telemetry system, and decode the commands transmitted from the surface. The
module will be composed of a micro controller, which includes memory, analog
to
digital converter, input/output modules, a motor driver module to control the
operation of the motor and a position sensor analog conditioner circuit used
for
interfacing the sleeve position sensors to the A/D converter.
A power Regulator converts the DC high voltage located on the cable into a
voltage level that can be utilized by the motor for the actuation of the
sleeve. The
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-12-
regulator can be a linear or switching device. This downhoIe application uses
a
switching device to provide a more efficient power conversion, to reduce the
heat
generated by the power supply, and to maintain a constant power delivered to
the
motor.
The telemetry module interfaces the downhole toot to the surface system
through an electrical cable. The module will have a half duplex communications
capability where only one device can send a signal on the cable at a time. The
telemetry modules can be attached to the downhole cable in parallel permitting
a
number of sleeves to be addressed and actuated from the surface individually.
The electromechanical module is composed of a stepper motor, gear box, a
follower nut, and a lead screw that controls the movement of the sleeve in the
s= _ ~_ ~ _ _
longitudinal axis of the tubing string. The motor is controlled by the
microprocessor
board which provides the necessary 1~C power and polarity for the proper
operation of
the motor. A gear box attached to the motor decreases the speed of actuation,
but
increases the torque which is necessary for the generation of sufficient force
for the
actuation of the sleeve. The follower nut and lead screw assembly interfaces
the gear
box to the sleeve, and allow the force generated by the gear box to be
used~for actuation
of the sleeve.
The sliding sleeve is composed of a tubing that can be screwed in line to the
production tubing with male threads on one end, and female threads on the
other end.
A preferred openings equivalent of about 1 %2 times the internal diameter of
the tubing
are located in the tubing to permit the fluids to flow from the formation to
the inside of
CA 02218259 1997-10-14
WO 97/30269 PCT/US97l02334
-13-
the tubing. It will be understood, however, that other ratios are selectable
while
maintaining desirable flow rates. For example, a I : I ratio of the openings
equivalent is
also acceptable. A sleeve located on the outside of the assembly covers the
opening
when in the closed position, and it exposes the opening to the formation when
in the
open position. The sleeve is attached to the follower nut and lead screw
assembly
located on the outside of the tool.
At least one position sensor is located in the sleeve and L.V.D.T. resolvers
or
linear potentiometers are mounted near the opening of the tool. The micro
controller
board monitors the position of the sleeve by sensing which sensor is being
affected by
the magnets.
For purposes of clarity, the operation of the sliding sleeve tool is
described, _.,..-~..~ _
below:
The surface system asks for the location of the sleeve, and status of the
entire
system. The microprocessor decodes the command and returns, via TEC line to
the
I 5 surface, the tool status information. Each tool includes a unique
electronic address that
allows the surface system to interface with the particular sleeve.
The surface system commands the downhole tool to open the sleeve to initiate
the production of the zone being controlled by the sleeve. To accomplish this
result,
the surface computer increases the DC voltage placed in the cable to allow
enough
power to be transmitted to the motor. It will be understood that while surface
decisions
- are indicated here, this is merely exemplary and all decision and evaluation
may be
accomplished in and by the downhole electronics and processor package.
CA 02218259 1997-10-14
WO 97/30269 PCTlUS97/02334
-14-
The microprocessor actuates the motor drivers to allow power to be placed at
the motor for the generation of the mechanical motion required to drive the
sliding
sleeve.
The processor monitors the position of the sleeve through a position sensor
and
turns off the power to the motor once the sleeve has reached its predetermined
or
desired resting location.
Where a surface system is also employed, the surface system lowers the voltage
levels upon detection of the low power consumption on the cable, and sends a
message
downhole inquiring about the status of the toot. The tool replies with the
location of
the sleeve.
Steps I through 5 can be repeated to close the sleeve. The only modification
is
that the command sent from the surface to the tool will be to close the sleeve
instead of
to open it.
The electronics are housed in an atmospheric pressure chamber located on the
outside of the sliding sleeve tubing. The system is preferably rated to 15000
psi, and
150 degrees on the Celsius scale. The maximum actuation power generated by the
electromechanical assembly is about 10,000 pounds. Equipment that has been in
use for
a period of time may require longer cycle times due to scaling and debris that
may have
accumulated over the service life of the tool.
In another embodiment of the invention, refernng to FIGURES 8 and 9, a
rotational sleeve 60 is employed as the flow control device instead of the
axially sliding
sleeve. Essentially the rotating sleeve functions in the same manner as the
sliding
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-15-
sleeve, by alignment of the outer slots 72 with the internal slots 74 or
misaligning the
same slots but does so in a rotary manner instead of the axial manner of the
conventional sliding sleeve. The rotary sleeve is operated by a motor 62
driving a gear
64 which meshes with teeth 66 on the insert 68. The rotational sleeve itself
is very
similar in function to a sliding sleeve but turns the inner sleeve to open,
choke or close
flow as desired. The outer sleeve is indicated by the numeral 70. As in the
embodiment described above, the present device is responsive to commands from
either a local downhole intelligence device or to a remote or surface input.
Signals are
carried by preferably TEC wire as more fully described above.
The rotational embodiment provides much of the same advantages as the linear
embodiment such as metered closing and opening with a high degree of accuracy.
=A -~~ ~ _ ,
regular motor using time and power parameters or a stepper motor may be
utilized
wherein the counts of the motor are used to determine the degree to which the
sleeve is
open or closed. While it is unlikely that the motor driven embodiment will
fail it is
nevertheless important in all oil well apparati to provide for a contingency
in the event
of a failure. Therefore and with respect to the rotational embodiment,
illustrated in
FIGURES 10 and 11 of the invention one contingency construction is to provide
a
specific key arrangement for opening or closing the sleeve by engaging the
opening
and closing features(shifting features 44) selectively. As is easily
understood from the
illustration in the identified FIGURES the shifting tool 80 includes springs
82 which
bias a key 84 having a short key length 86 to close the flow device and a long
key
length 88 to open the device. It will be apparent from the drawings that for
the
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-16-
contingency embodiment of the tool a second set of windows is required.
Windows 90
are, in normal operation of the invention, downhole of the external windows of
the
outer sleeve and are not in communication therewith. Upon the need to
contingently
actuate the flow device, the window 90 can be shifted into communication with
the
external window. In order for the invention to function normally in a reliable
manner,
it is advisable to provide means to prevent the axial movement of the tool.
This is most
preferably a shear ring which is illustrated in FIGURE 10 in the sheared
position as 92
and 94. It will be understood that many other similar methods of holding the
tool in the
desired position are applicable and are within the scope of the invention.
In the third embodiment of the invention, refernng to FIGURES 12-16 a ball
screw assembly is employed wherein the ball seat member is annular and
circumferentially spans the production tube. The ball seat member is
illustrated in
FIGURE 15 by numeral 110. Individual ball grooves 112, it will be understood,
are
actually a single helical groove similar to a screw thread. Ball seat member
110 is in
operable communication with ball nut i 14 which includes a plurality of ball
bearings
(not shown) that are received in ball grooves 112. Turning of ball nut 114
imparts a
somewhat rotational and somewhat longitudinal force on member 110, however,
key
118 which is fixedly connected to ball seat member 110 and locks member 110
into key
way I20 of key sleeve 127 which is itself prevented from rotating by key 128
which
extends into drive housing 13 8. The two key and keyway systems prevent any
actual
- rotational movement of member 110. Therefore, ali of the force transmitted
to member
110 is translated to longitudinal motion of member 110. As one of ordinary
skill in the
CA 02218259 1997-10-14
WO 97/30269 PGT/LTS97/02334
-1 ?-
art should appreciate, member 110 in drawing FIGURE 15 is illustrated directly
radially outward of a conventional sliding sleeve insert 122. Insert I22 is
modified in
that it includes ball seat snap rings 124 and 126 which act to prevent
relative movement
between ball seat member I 10 and insert 122. It v~rill be understood then
that
S longitudinal movement of ball seat member 1 I O requires longitudinal
movement of
insert 122 to the same degree. Moving the insert uphole opens the sliding
sleeve and
moving the insert downhole closes the sliding sleeve.
The original rotational impetus of the invention is provided by an annular
motor
130 which comprises an outer annular winding and an inner annular arrangement
of
permanent magnets. The winding is preferably mounted to the LD. of an outer
housing
tube (i.e., motor housing 142). The magnets are mounted on an inner tube
(i.e., the
motor shaft 132). The most preferred magnets are samarium cobalt. The motor
operates step wise with each powering of the coil. The motor shaft 132 extends
to the
interface with ball nut 114. Movement is transmitted from motor shaft 132 to
ball nut
114 by a rabbet arrangement wherein each of the motor shaft 132 and the ball
nut 114
are provided with a tooth or recess complimentary to that occurring on the
other
member and occurring approximately every ninety degrees. Ball nut 114 and
motor
shaft 132 are maintained in engagement with one another by thrust bearings 134
and
136. These are maintained in place respectively by key sleeve 127 and snap
ring 129.
The area is protected by drive housing 138. This is threadedly connected to
TEC
connector housing 140 at the downhole end thereof and to motor housing 142 at
the
uphole end thereof. Motor housing 142 is in turn connected to a turn buckle
144 which
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
- -18-
threads onto electronic sub 146.
The downhole processing center and electronics boards to signal and determine
operation of the actuator are contained within atmosphere chamber I48 in
electronic
sub 146 and are covered hermetically by electronics cover 150. The downhole
electronics enable the invention to compute such parameters as openness of the
sleeve;
flow rate; water cut; etc. and take corrective action with or without surface
input. The
electronics also closely monitor the position of the sliding sleeve by
employing
preferably a Resolver having a 360 ° position range. A resolver gear is
meshed to a
ring gear having a ratio sufficient to allow accurate indication of sleeve
position. The
arrangement is discussed further hereunder.
The motor and ball screw assembly are preferably maintained in a dielectric p
fluid to ensure cleanliness and long operational life. In order to maintain
the fluid in
these component areas metal spring energized seals are preferably employed.
And
while seals of this nature are highly reliable, balancing pressure across the
seal is
I S advisable to prevent substantial contamination by wellbore fluids.
In the most preferred embodiment of the invention, balancing of pressure
between the production fluid and the dielectric fluid is accomplished by
providing
preferably five compensation cylinders 152 each of which contain a compensator
piston
154. The preferred piston comprises a metal spring energized seal stack with
an arlon
seal cover (commercially available from Greene Tweed) and separates the
dielectric
fluid on one side thereof from the wellbore fluid on the other side thereof_
Each
compensation cylinder 152 includes an inlet 156 to allow wellbore fluid from
the inside
CA 02218259 1997-10-14
WO 97/30269 PCT/ITS97/02334
-19-
of the production tube and thus the pressure associated therewith to flow into
compensation cylinder 152 and thus force compensator piston 154 downhole
whereby
the pressure of the dielectric fluid in communication with the other side of
the piston is
increased. Since the dielectric fluid at the downhole side ofthe piston is
contiguous
with the fluid surrounding the drive components of the invention, and because
the
pressure across the piston is self equalizing, pressure on the seals
separating the
dielectric fluid from the environmental fluid is necessarily balanced. By
allowing the
pressure of the dielectric fluid around the working components of the
invention to
remain approximately equal to the pressure inside the production tube due to
the
compensation system, seal life is extended. In the most preferred embodiment
of the
invention, apertures 156 are drilled directly into compensation cylinders 152
as
illustrated in FIGURE 13A.
Referring to FIGURE I3B, compensation cylinders 152 are visible in end view
and compartment i 58 is visible which houses the resolver and a synchro for
the annular
motor of the invention. Feed throughs 160 are also illustrated. The resolver
of the
present invention is intended to convey information from the ring gear to the
downhole
processor in the electronics package which translates the information to a
number of
inches of sleeve opening and transmits that information to the surface. This
provides
immediate and accurate information to the surface about the position of the
sliding
sleeve. The sleeve is optimally moveable through eight inches of stroke and,
therefore,
resolver 158 optimally employs a ratio of 256:1 with respect to ring gear 170
on the
motor shaft. Three hundred and sixty degrees of rotation of the resolver most
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
- -20-
preferably equates to eight inches of stroke, thus the preferred ratio. By
inputting a
sinusoidal reference signal into the resolver from the electronics board a
sine wave
output signal and a cosine wave output signal are generated. A comparison
between
the reference signal and the output signal to determine in what quadrant the
waves
cross provides the necessary information to enable the downhoie or other
electronics
calculate the angle between these signals. Subsequent to determining the angle
between the signals the electronics will then calculate linear displacement of
the tool
with accuracy to within about 1/8". This information is transmitted uphole for
monitoring and evaluation. For power feed through to the electronics 148, most
preferably at least one multipin connector 172 is employed. In general these
connectors may be employed anywhere in the invention where the TEC wire enters
or _ ~ ~ i
exits the interior of the tool and at the beginning and end thereof to provide
power to
tools lower in the wellbore.
In order to prevent pistons 154 from extending beyond the ends of
compensation cylinders 152, a piston retainer 162 is positioned with five
fingers
extending toward each of the five compensative pistons 154 and ending in
position
sufficient to prevent the escape of compensator pistons 154 from compensation
cylinders 152. As will be appreciated, any number of fingers, pistons and
cylinders are
possible as desired. Five is merely preferred.
In a fourth embodiment of the invention, referring to FIGURES 18-22, a
smaller diameter ball screw assembly is mounted eccentrically within a housing
and
operates through a connecting shaft against a drive yoke to actuate, via a
shear out
CA 02218259 1997-10-14
WO 97/30269 PCT1US97/OZ334
- -21-
member, the insert of an otherwise conventional sliding sleeve. One of
ordinary skill in
the art will appreciate that the drive unit 210 (referring to FIGURES 19 and
20)
includes a motor and a ball screw assembly which is not independently
illustrated. The
ball screw assembly is conventional and is commercially available from Astro
Instruments Carp. The drive unit is contained in a compartment filled with
dielectric
fluid the compartment being def ned by motor housing 212 and motor cover 214.
Motor cover 214 is threadedly connected to the yoke housing 216 which is, in
turn, .
connected to the conventional sliding sleeve (available commercially from
Baker Oil
Tools in Houston, Texas) to provide a unified structure within which the drive
yoke
220 may pass to actuate the insert 240. Drive yoke 220 is connected to insert
240 via a
shear out structure 222. Structure 222 provides the connection to insert 240
via a
plurality of, and preferably five, dogs 224 (see FIGURE 21A). The dogs
facilitate
transition of movement without weighting any of the shear out screws 226
(which
screws preferably number 10) during normal operation of the tool the shear out
structure itself will be discussed subsequently.
Drive yoke 220 is coupled to the drive unit 210 via a connecting shaft 250
which extends or retracts depending upon the polarity of power fed to the
drive unit
motor which then actuates the conventional ball screw assembly in the
appropriate
direction. The uphole end of motor housing 212 is supplied with power
connectors 266
(see FIGURES 18 and 19A) and is adjacent electronics housing 262. In the most
preferred embodiment of the invention a space of not more than 1/8" is
provided at the
joint 263 between motor housing 212 and electronics housing 262 because motor
cover .
CA 02218259 1997-10-14.
WO 97/30269 PCT/US97/02334
-22-
threads 265 and yoke housing threads 267 are mated simultaneously. This
requires
either play within the tool or a timed thread cutting operation which is
generally
prohibitively expensive. The inventors hereof therefore prefer to allow the
stated
amount of play in the tool. Moreover, shoulder 269 is preferred for
manufacture of the
tool in order to reduce friction of the motor cover 214 against MSE seal 268.
In other
words cover 214 is machined to a lesser thickness until just downhole of the
intended
sealing surface for MSE 268. As the tool is made up, the cover 214 slides
easily over
the MSE seal until it is almost completely engaged. At this point the sealing
surface
area provides a much higher degree of friction on the seal. This machining
results in
shoulder 269 which is illustrated in the drawing FIGURE. The atmospheric
chamber
260 encloses the downhole electronics and processing components and is
hermetically
sealed by electronics cover 264. The electronics perform the evaluation tasks
and
supply power to drive unit 210 in motor housing 212. The electronics are
preferably
supplied by TEC wire for which a connector 266 is sealed within the end of
electronics
housing 262. Information from the surface and from downhole sensors, including
a
position sensor, is processed downhole resulting in a determination regarding
any
necessary change in the sleeve and appropriate actuation thereof if necessary
by
delivery of a particular polarity of power being delivered to the motor of
drive unit 210.
Assisting the sealing of the atmospheric chamber by electronics cover 264 is
most
preferably a pair of MSE (metal spring energized) seals 268 or welded
connections.
Motor housing 212 is attached to the yoke housing 216 in the vicinity of the
downhole
extent of connecting shaft 250 as illustrated. In the most preferred
embodiment of the
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-23-
invention there are bolts/alignment pins 27 i (see FIGURE 21 C) that join the
motor
housing to the yoke housing and prevent the motor housing from moving relative
to the
yoke housing. A spacer 270 is inserted at the joint line between motor housing
212 and
yoke housing 216, said spacer having projections 272 to maintain seals 274
within the
respective gland areas.
Referring to FIGURES 20, 21 and 21B, one of skill in the art will recognize
TEC connector 276 leading to an exterior TEC wire (not shown). Conventionally,
such
wires have been run external to the tool down to the next tool for which power
is
require. In order to further advance the present invention a cover 278 is
engaged with
the sliding sleeve via wings 279 and provides a passage through which the TEC
wire
shown in this view as numeral 281 can pass while protecting the same from s
environmental impact. Cover 278 extends along the extent of lower sub 280
generally
comprising the conventional sliding sleeve. Cover 278 is further maintained in
contact
with lower sub 280 by collar assembly 282. Collar assembly 282 comprises wire
lock
I 5 284 and wire cover 286. Wire lock 284 provides a radiused inlet such that
TEC wire
288 is not kinked upon bending ninety degrees prior to being coiled around the
O.D. of
the lower sub 280. TEC wire 288 is preferably coiled for several revolutions
in order
to provide additional wire slack so that making up the connection in the field
will not
require excessively tight measurement toierances. To protect this wire, wire
cover 286
is engaged around lower sub 280 in such a manner that extension 290 covers the
coiled
wire 288 to protect it from environmental impact. Wire cover 286 also extends
over
cover 278 to maintain it against lower sub 280. It will be appreciated from
FIGURE 22
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-24-
that the wire lock 284 is in a generally conventional collar design having a
hinge which
is not shown and is approximately one hundred eighty degrees away from bolt
292
which when threaded into wire lock 284 secures the same to lower sub 280. Wire
cover 286 operates in the same manner and further explanation is therefore
deemed
unnecessary.
In the unlikely event of an actuator failure, the sliding sleeve can be
actuated
conventionally with a prior art shifting tool once the actuator of the
invention is
disconnected from the sliding sleeve insert. To facilitate this end, the shear
out
structure of the invention is operated. The shear out member 222 includes
shoulder
228 which is employed only when the drive unit of the invention has failed and
it is
required to move the shear out structure so that conventional shifting tools
may bea _,..P_-
employed to operate the sliding sleeve. Shoulder 228 is beared upon by a
shifting tool,
which is conventional in the art, to shift the structure 222 uphole. A stroke
length is
provided by space 230 to provide sufficient room for shear out 222 to move
uphole and
allow dog 224 to slip radially inwardly out of engagement with drive yoke 220.
A snap
ring 232 is provided to prevent shear out 222 from moving downhole after it
has been
sheared. This is important because if the shear out structure 222 'moves back
downhole, it can reintroduce dog 224 to drive yoke 220. This defeats the
operation of
the structure 222 and prevents operation of the sliding sleeve by conventional
shifting
tools and techniques. Snap ring 232, upon uphole urging of shear out 222 will
expand
into annular groove 234 thus preventing the subsequent downhole movement of
shear
out 222. It is noted that in the most preferred embodiment of the invention,
for
CA 02218259 1997-10-14
WO 97/30269 pCT/US97/02334
-25-
manufacturing purposes, an assembly bore 236 is provided whereby snap ring 232
may
be forced into shear out 222 and out of engagement with annular groove 234 in
order to
set the shear out 222 during manufacture. It should be noted that his shear
out structure
is employable with each of the actuator tools of the invention.
in a fifth embodiment of the invention, referring to FIGURES 23-30, a
conventional sliding sleeve is actuated by a motor and gear train combination
powering
a lead screw which is connected through a shear release mechanism, identical
to that
discussed hereinabove, to the insert of an otherwise conventional sliding
sleeve.
Referring first to FIGURE 29, a perspective schematic view of the motor gear
train and
lead screw of the invention is illustrated. A brief perusal of the figure will
provide a
detailed understanding of the motor gear drive and lead screw gear to one of
ordinary
skill in the art. Motor 310 includes a motor pinon 312 which meshes with
follower
gear 314 which is mounted on auxiliary shaft 316 and, therefore, mated without
relative
rotation to auxiliary gear 318. Gear 318 meshes with lead screw drive gear 320
which,
in turn, drives lead screw gear 322. Lead screw gear 322 includes threads cut
on the
LD. thereof of the same TPI as threads cut on the O.D. of actuator sleeve 324
(which is
a flow tube). Therefore, by powering motor 310 in one direction or the other
based
upon polarity, the actuator sleeve 324 is driven uphole or downhole by the
threads
thereon. While actuator sleeve 324 would prefer to turn rotationally as
opposed to
move longitudinally, following the path of least resistance, sleeve 324 is
provided with
a key (visible in FIGURE 25B as numeral 329) attached to the end of 328 of
linear
potentiometer 330. Referring to FIGURES 25E and 30, one of ordinary skill,in
the art
CA 02218259 1997-10-14
WO 97/30269 PCT/US97/02334
-26-
will appreciate the preferred location of linear potentiometer 330 with
respect to other
components of the invention. Also illustrated well in FIGURE 25E are alignment
dowels 332 which assists in maintaining the several components of the
invention
relative to one another. Actuator sleeve 324 continues on to FIGURE 26 wherein
it is
concentrically radially outside of insert 240 of the conventional sliding
sleeve. One of
skill in the art will appreciate that the shear release mechanism 222 is
identical to that
of the previous embodiment and, therefore, is not explained in detail here.
Power
supply to and through the tool is preferably by TEC line which is identified
by numeral
340. Downhole electronics are similar to those described above and are housed
in
atmospheric chamber 350 bounded by electronics housing 352 and electronics
cover
354. Power connections are supplied by conventional connectors 360 which are
employed as desired due to convenient routing ofthe wire through the tools.
While preferred embodiments have been shown and described, various
modifications and substitutions may be made thereto without departing from the
spirit
and scope of the invention. Accordingly, it is to be understood that the
present
invention has been described by way of illustration and not limitation.
What is claimed is:
