Note: Descriptions are shown in the official language in which they were submitted.
CA 02458495 2004-02-24
IMPROVED PACKER WITH INTEGRATED SENSORS
Technical Field
The present invention relates to the detection of equipment status in a
borehole.
More specifically, it relates to detecting the amount of expansion and the
pressure inside
a hydraulically controlled packer.
Background of the Invention
1n the field of oil and gas drilling, where a borehole may extend a mile or
further
below the surface, it has long been desirable to have knowledge of the
position and
configuration of the equipment that one can no longer see. One specific case
in point is
the use of packers.
Figure lA shows a simplified schematic of a cross-section through a well,
which
can be nearing completion: A dernck 110 supports a string of pipe 112, which
is run into
a cased borehole 114: Figure 1B is an enlargement of a portion of Figure lA,
showing
the wall 116 of the borehole, casing 118, casing cement 12p, pipe 112, and
packers 122.
The packers 122 provide a seal between the outside of the pipe 112 and the
inside of the
casing, so that one section of the cased borehole 114 can be isolated from
another. This
can be to allow pressure to be exerted in a specific formation, e.g., for
fracturing a
producing formation, to be able to separately draw out the oil and gas
produced at
different depths, or for other reasons
There are numerous types of packers, which differ in their material and form,
but
an exemplary packer uses hard rubber parts to seal between the downhole tubing
and the
casing or borehole. These packers will have a toroidal, or doughnut-shaped,
section of
rubber on the outside wall of the drill string. Figure 2A shows a view of such
a packer as
it is inserted into the borehole. At this point in time, the rubber making up
the packer lies
close to the pipe supporting it, so that there is no interference with the
walls of the
borehole as the packer is inserted. A view looking downward at the packer is
seen in
Figure 2B. Once the packer is in position, the pipe supporting the packer is
manipulated
so that the rubber is compressed in a longitudinal direction. As the toroid is
forced into a
smaller distance longitudinally, it bulges outward to seal against the inside
of the casing,
CA 02458495 2004-02-24
as seen in Figure 2C. Figure 2D is a view looking down the borehole at the
expanded
packer. Another type of packer is inflatable and can be filled with a liquid,
once it is in
position. So far, however, this type of packer has been used much less as it
will not hold
against a large differential pressure across the packer.
As mentioned above, one of the problems in judging whether the packer is
correctly seated is the inability to visualize the packer or to receive direct
feedback about
what is happening with the packer. Judging the proper seating of the packers)
involves
monitoring indirect feedback at the surface, primarily in the form of surface
pressure
changes. This can involve conducting pressure tests, where a liquid is pumped
into the
sealed portion to be sure that the packer holds under necessary pressures. No
information
is directly available from the packer on its displacement or its internal
condition. It would
be desirable to obtain information from the packer so that it could be more
clearly
determined if it is properly positioned.
CA 02458495 2004-02-24
SUMMARY OF THE INVENTION
In the innovative packer, sensors are included in an inflatable packer to
measure
the pressure inside the packer and the distance that the outside wall of the
packer moves
during inflation. This data is communicated to a control module that monitors
and
controls the operation of the packer; as well as to a central downhole and/or
surface
controller.
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CA 02458495 2004-02-24
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features believed characteristic of the invention are set forth in
the
appended claims. The invention itself, however, as well as a preferred mode of
use, further
objects and advantages thereof, will best be understood by reference to the
following
detailed description of an illustrative embodiment when read in conjunction
with the
accompanying drawings, wherein:
Figure lA shows a simplified schematic of a cross-section through a prior art
well.
Figure 1B is an enlargement of a portion of Figure lA,
Figures 2A and 2B show a prior art packer before and after activation.
Figures 2C and 2D show a top view of the packers of Figure 2A and 2B
respectively
Figure 3 shows a first embodiment of the innovative packer.
Figure 4 shows an alternate embodiment of the innovative packer.
Figure 5 is a flowchart demonstrating a method of using the innovative packer.
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CA 02458495 2004-02-24
DETAILED DESCRIPTION OF THE DRAWINGS
A first embodiment of the disclosed packer will now be discussed in further
detail
with reference to Figure 3. This drawing shows only the short section of the
pipe string
that contains the inflatable packer. It will be noted that this drawing is not
done to scale
so that the innovative features can be emphasized. Seen in the drawing is the
inflatable
packer 300, which wraps completely around the section of pipe 320 containing
it. Not
present in the drawing are the threaded ends to the pipe section by which the
packer is
made up as part of a string of tools. The pipe 320 contains a passageway 322
through
which fluids can be pumped into the well or production fluids removed from the
well.
Packer 300 is of the inflatable type, where a fluid can be pumped into the
packer 300
through a hydraulic line 302 to expand the packer. In the presently preferred
embodiment, the fluid used is a magnetorheological fluid, comprising iron
particles in an
oil base. With a magnetorheological hydraulic fluid, the flow of hydraulic
fluid into and
out of the packer can be controlled through the use of an electromagnet 303.
Further
information regarding the use of magnetorheological fluids in drilling and
production can
be found in co-pending application 10/090,054, filed March 1, 2002.
Two sensors are included as part of this innovative packer. The first of these
sensors is a fiber optic pressure transducer 304. This transducer has at least
one surface
that is positioned to detect the pressure within the interior of the packer
300. The pressure
detected is transformed into an electrical signal, which is sent to controller
306. Another
type of transducer is used to detect the inflation of the packer. In this
embodiment, a
rotary potentiometer 308 is used, the basic concept of which is shown in
Figure 6. A
length of cable 310 is wound around a spindle 340, so that as cable 310 is
pulled out of
the potentiometer 308, the spindle is rotated a number of turns proportional
to the
distance the cable travels. These rotations are translated into another
electrical signal,
which is again sent to the controller 306. As seen in the figure, one end of
cable 310 is
attached to the outer wall 312 of the packer 300 by a cable clamp 314. The
cable between
the potentiometer 308 and cable clamp 314 runs over pulley 316, which allows a
change
of direction. As the packer is inflated, the cable 310 is pulled out of
potentiometer 308,
causing an appropriate signal to be generated. The shaft of the potentiometer
308 is
spring-loaded so that it remains in its zero position until the packer is
inflated. The
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sensors 304, 308, controller 306, and the electromagnet 303 that controls the
flow of fluid
into the packer 300 are connected by bus 318 to each other and to a battery
319, which
provides power.
Figure 4 shows an alternate embodiment of the innovative packer 300. In this
embodiment, ultrasound transducer 330 bounces a signal aff a metal plate 332
attached to
the wall of the packer 300 to measure the inflation of the packer 300. From
the signals
bounced back from the device 332, the transducer 330 can determine the
distance the
wall of the packer 300 has moved during inflation. The pressure can be
measured in this
embodiment can be another form of pressure transducer 304, such as a quartz
pressure
transducer or a pressure gauge transducer. Like the prior embodiment, this
information
can be collected by a controller, which controls the electromagnetic valve
used for
inflating the packer 300. Additionally, a signal can be sent uphole via
transmitter 334,
where the pressure and displacement can be monitored and the action of the
packer
further controlled by the operator. This signal can be sent by any of the
known methods
of sending messages to the surface.
A method of using the disclosed embodiments of the invention will now be
described with reference to the flowchart shown in Figure 5. The method begins
with the
packer being inserted into a string of tools (step 510) that will be used for
finishing the
hole or during production, depending on the type of packer used. A hydraulic
line will be
also be attached to the packer, as is well known in the art, although the
valve to the
packer will be closed so that the packer will not be unintentionally inflated.
Once the
string of tools is completed, ftwther pipe is added to extend the string to
the required
depth (step 512). This depth will have been determined by the operator to
place the
packers) at appropriate locations relative to the formation of interest. In a
presently
preferred embodiment, the sensors are not powered at the time the packer is
being
installed and positioned, although tests may be run to sure that it is
functioning correctly.
After positioning, a signal is sent (step 514) to the controller 306 to
activate the packer
and the sensors. At this time, the controller will open the electromagnetic
valve (step 516)
to allow hydraulic fluid into the interior of the packer chamber 300. At the
same time, the
sensors 304, 308 will be activated to detect the movement of the outside wall
of the
packer and the pressure within the packer itself. The controller 306 will
monitor these
CA 02458495 2004-02-24
signals. In a properly functioning packer, the pressure will rise gradually
while the packer
expands until the outside wall of the packer contacts the casing of the hole.
Once the
sensor detecting the location of the outer wall of the packer indicates that
the casing is
contacted, the packer will continue to be filled and pressurized until
pressure sensor
indicates that the predetermined pressure for sealing is reached. At that
point, the
controller 306 will shut (step 518) the valve 303. Optionaliy, the controller
will also send
signals (step 520) back to the operator on the surface, so that the process
can be
monitored topside. If the packer installation is not permanent, then the
packer can
optionally be removed when necessary by reversing the steps. In this instance,
a si~nal is
sent (step 522) to the controller 306, instructing it to deflate the packer.
The valve is
opened (step 524) so that the hydraulic fluid can be pumped out and the
monitors are
used to detect (step 526) when the packer is returned to its resting, deflated
position.
When that point is reached, the string can be withdrawn (step 528) as is known
in the art.
Thus, it can be seen that the innovative changes to a packer will provide much
needed information, both to automatic controllers downhole and to the
operators on the
surface. The advantages of the innovative packer include the following: 1) a
direct
indication about the integrity of the packer seal is provided, 2) the safety
of the overall
packer operation is increased, and 3) operating time is saved by avoiding
lengthy surface
pressure tests to check the integrity of the packer seal.
It will be understood by one of ordinary skill in the art that numerous
variations
will be possible to the disclosed embodiments without going outside the scope
of the
invention as disclosed in the claims.
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