Note: Descriptions are shown in the official language in which they were submitted.
Title: Fracking System with Wireline Shifted Ports Docket:
PATFAM93-CA
and Real-Time Electronic Monitoring System
FRACKING SYSTEM WITH WIRELINE SHIFTED PORTS AND REAL-TIME
ELECTRONIC MONITORING SYSTEM
TECHNICAL FIELD
[0001] The
present invention relates generally to oil and gas well completion.
More particularly, the present invention relates to a string for use in
stimulating multiple
intervals of a wellbore.
BACKGROUND
[0002] In
conventional coil tubing ("CT") fracking systems, the operator pumps
fluid down the annulus between the coil tubing and the casing. Since the coil
tubing
occupies much of the volume inside the casing, the pumping rate used by the
operator
is limited. Operators want to achieve over 100 barrels per minute, but the
presence
of the coil tubing inside the casing limits the pumping rates.
[0003] As
stage counts increase, "pressure budgets" for a wellbore are being
stretched (since every stage in the wellbore acts as a drain on the pressure
budget)
until at some point, there is not enough pressure available for a given stage
to generate
meaningful amounts of energy for stimulating and completing that stage. As an
operator puts more and more seats in the casing, every seat that the bridge
plug
passes, needs to have a pressure drop, which in turn means that as the count
of
seats/stages increases from 40 to 70 and beyond, the operator starts to lose
the ability
to obtain high pump rates. That is, as the operator starts to run out of
pressure-drop
budget, and has to start to reducing rates near the toe. A method and
apparatus are
required to support more stages, while reducing the drain on pressure budget
that
provides energy for powering operations at each stage.
[0004] A frack
initiated by an operator at a stage can converge with another frack
in a neighbouring stage or well. A method and apparatus for detecting and
reporting
conditions that indicate the imminence of such an undesirable condition,
before it
becomes excessively costly to reverse, is required.
1
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports Docket:
PATFAM93-CA
and Real-Time Electronic Monitoring System
[0005] In
known CT production/stimulation systems, a radially extendable key is
provided on a bridge plug to engage a matching profile on the inside of one or
more
of the sleeves in the production/stimulation tubular, so that when pressure is
applied
to the bridge plug to push it through the sleeve, the profile engages the key.
Upon
engagement, the engaged sleeve is actuated by the pressure-exposed plug. In
general, the engaged sleeve is moved from a port-closed position covering a
port, to
a port-open open position exposing the port. After
treating a stage, the
production/completion operations can be moved to a next stage, by using a tool
controlled from surface to retrieve the bridge plug and pull it up-hole to a
next stage,
using coil tubing. The problem with these systems is that the plug is pulled
back up-
hole using coiled tubing, which as mentioned above occupies the inner volume
of the
casing, which in turn reduces pump rates.
[0006] Known
ball/plug drop completion systems suffer from the problem of
erosion of the downhole seats used to catch the balls/plugs. As is understood
in the
art, progressively smaller seats are used for stages that are closer to the
surface. As
the seats get smaller, the bridge plugs have more of a tendency to hit
critical velocities
capable of eroding the seats or the areas just past the seats upon engagement.
[0007] Known
plug and pea completion systems suffer from the problem of
erosion of the perforations in the casing (fluid exit points). When operators
perform a
plug and pert operation, they try and distribute the fluid entering the
formation by
shooting an appropriate number of perforations in each stage, to create holes
in a
casing that generate an appropriate pressure drop. The problem is that if/when
sand
arrives from the formation through a hole created with the pert gun, the hole
tends to
get bigger and bigger as it erodes. A perforation that starts out for example,
sized at
a half-inch in diameter, can grow to the diameter of a Coke can, due to
erosion. This
means that instead of getting a predictable distribution of pressure across
the stages,
the pressure becomes very different and very unpredictable from stage to
stage. In a
lot of cases, there is no even distribution of pressure at all between the
stages.
[0008] Screen-
out is a condition that occurs when the solids carried in a treatment
fluid, such as proppant in a fracture fluid, are over-displaced into the
formation, thus
creating a fluidic bridge across the perforations or similarly restricted flow
area. This
2
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports Docket:
PATFAM93-CA
and Real-Time Electronic Monitoring System
creates a sudden and significant restriction to fluid flow that causes a rapid
rise in
pump pressure, which is problematic during fracking operations.
[0009] United
States Patent Publication No. U52013/0168090 (Thennig et al.)
assigned to the applicant, describes an actuator tool configured to move
through the
tubing string that is actuated by wireline, to set a seal in the tubing string
to actuate a
closure to open a first port, and then to actuate a second closure to open a
second
port that is uphole from the first port. This can provide an advantage over
coiled tubing
systems because wireline occupies much less room in the casing than coil
tubing,
which in turn means the inner volume restriction in the wellbore is far
smaller than that
created by the coil tubing, which ultimately means that higher pump rates can
be
supported. One disadvantage of wireline, however, is that sometimes one cannot
apply a strong enough force to a wireline cable to pull up a bridge plug to a
next stage,
since the wireline cable, in certain circumstances, can snap under the massive
force
that might be required to pull up the bridge plug. A break in the wireline
would require
the operator to spend time and money using an intervention tool to retrieve or
clear
away the wireline and the bridge plug, which is costly.
[00010] United
States Patent Publication No. US2017/218725 (Schnell et al.)
assigned to the applicant, describes an actuator dart which is run in on a
wireline. The
dart has an engagement mechanism adapted to engage a target tool on receipt of
ae
electrical signal, while dart removal mechanism on the target tool releases
the
engagement mechanism once the target tool was actuated. The wireline allows
for
depth determination for appropriately activating the dart inside the tubing
string and is
also used to send the signal when based in depth measurements. This can
provide an
advantage over other systems in that the dart can actuate a large number of
different
tools. As indicated above however, the wireline cable, in certain
circumstances, can
snap under the massive force that might be required to move the dart inside
the
wellbore.
SUMMARY
[00011]
Embodiments described in this specification are directed to a fracking
system that uses a treatment string assembly insertable into the inner bore of
a
wellbore liner, which uses a wireline, rather than coiled tubing.
Specifically, a bridge
3
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
plug attached to a wireline has locking keys for engagement with sleeves of
various
devices/tools installed in the wellbore for performing the actions needed
during various
stages of the productions/stimulation processes.
[00012] In
accordance with a broad aspect of the present invention, there is
provided a plug assembly to operate one or more downhole tools installed in a
wellbore
comprising: a bridge plug with an uphole end and a downhole end, adapted to
engage
with a target downhole tool; a wireline attached to the uphole end of the
bridge plug to
transmit bridge plug control signals to and from the bridge plug; and a
tractor at the
downhole end of the bridge plug, adapted to aid displacement of the bridge
plug.
[00013] In
accordance with another broad aspect of the present invention, there is
provided a method for operating a target downhole tool placed in a tubing
string in a
wellbore, the tool comprising a port and a sleeve covering the port, said
method
comprising: moving a bridge plug, connected to a wireline extending from
surface at
its uphole end and a tractor connected at its downhole end, towards the tool;
actuating,
by a bridge plug control signal received via the wireline, the bridge plug to
engage with
the sleeve of the target downhole tool; actuating, upon engaging the bridge
plug with
the sleeve, the bridge plug by hydraulic pressure to displace the sleeve
covering the
port to open the port; and pumping a fluid through the tubing string and the
port for
fracking a part of the wellbore adjacent to the bridge plug.
[00014] In
accordance with another broad aspect of the present invention, there is
provided a method of fracking a stage of a tubing string placed in a wellbore,
comprising: installing packers to support the tubing string and isolate the
stage;
installing in the stage a target downhole tool comprising a port and a port
covering
sleeve; attaching a bridge plug connected at its uphole end to wireline
extending to
surface, and at its downhole end to a tractor; moving the bridge plug towards
the target
downhole tool; in response to bridge plug control signals received over the
wireline,
actuating the bridge plug to engage the port covering sleeve to open the port;
displacing the port covering sleeve to open the port; controlling the tractor
to retract
the bridge plug from the stage; and pumping fracking fluid through the port to
frack a
formation adjacent to the port.
4
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00015] In
accordance with another aspect of the present invention, there is
provided a bridge plug for opening a port of a downhole tool installed in a
tubing string,
comprising: a body with an outer circumferential surface, a downhole end and
an
uphole end; a packer element at the downhole end enabled to adopt an unset
position
during run-in of the bridge plug, and a set position for sealing the tubing
string after
run-in of the bridge plug; at least one key disposed on the outer
circumferential surface
and enabled to assume a retracted state while moving the bridge plug to the
downhole
tool, and an expanded state for engagement with a port closure to move a
sleeve away
from the port after moving the bridge plug to the tool; and a wireline
termination
attaching the bridge plug to a wireline at the uphole end, the wireline
termination
adapted to receive at least one bridge plug control signal for driving the
packer element
into the set position and for releasing the one or more keys in the expanded
state.
[00016] The
system removes or significantly reduces the force applied to the
wireline to move a bridge plug from stage-to-stage within the casing/wellbore
after a
stage is treated by using an alternative mechanism to move the bridge plug
further
uphole, in the form of a tractor attached and proximate to the bridge plug.
[00017]
Embodiments described herein provide a production/stimulation system
that has at least the following advantages over prior art coil tubing fracking
systems
known in the art: supporting an unlimited stage count; moving the bridge plug
more
quickly and efficiently between stages; more easily preventing screen-out and
the
over-displacement of proppant that often occurs with conventional fracking
systems;
and significantly reducing erosion of both seats and perforations.
[00018]
Advantageously, the apparatus and method described herein allow a
wellbore treatment system and method that leaves a fully open internal
diameter (ID),
since protruding seats or stops are not required to stop the plug. Because of
the
smaller profile of the wireline as compared to coiled tubing, embodiments that
employ
wireline do not occupy as much of the inner bore of production/fracking
tubular (or
open hole), and therefore enable higher pumping rates. The bridge plug can be
rapidly
moved around from stage to stage, without using either coiled tubing or
wireline that
can snap if exposed to too much pressure, by providing a power source that can
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
generate the force to move the bridge plug in or near the bridge plug itself,
as opposed
to using force applied from surface.
[00019]
Furthermore, this system can be used in various borehole conditions,
including open holes, vertical holes, straight or deviated holes.
[00020] Since
the bridge plug uses the wireline, it can also be equipped with
parameter-measuring equipment that operates downhole, and then report measured
parameters to surface in real time using the wireline as a communication
conduit.
Moreover, the real-time readings can be correlated to the location of the
bridge plug,
which is always known by the length of the deployed wireline. This real-time
data
gives the operator the opportunity to readily anticipate, and thus alleviate
the
deleterious effects of, screen-out and the over-displacement of proppant.
[00021] Some
embodiments employ a combination of features described herein to
provide a resilient system that supports higher pump rates, an increased
number of
stages in a wellbore, and real-time parameter measurements which can be used
by
operators to detect screen-out and the over-displacement of proppant. In
addition, the
system described herein addresses the issue of erosion, and can create minimum
restrictions inside the wellbore as compared with known coiled tubing systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[00022]
Figures 1A and 1B, also collectively referred to as Figure 1, illustrate
schematic views of a fully cased/lined wellbore, and an open hole wellbore,
respectively, with a plurality of deployed downhole tools.
[00023] Figure
2 illustrates an embodiment of a bridge plug deployable in the
tubing strings of Figure 1 by a wireline.
[00024]
Figures 3A and 3B, also collectively referred to as Figure 3, show
engagement of a bridge plug of Figure 2, with a port closure device of a
downhole tool.
In Figure 3A the bridge plug engages the inner surface of the downhole tool,
and in
Figure 3B the bridge plug engages the port closure device.
[00025] Figure
4 illustrates the bridge plug opening the ports of the downhole tool
to enable fracking.
6
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00026]
Figures 5A-5C, also collectively referred as Figure 5, illustrate an
exemplary embodiment of the bridge plug with a fluid passage for equalization
of
pressure in the tubing string.
[00027]
Figures 6A-6C, also collectively referred as Figure 5, show a sectional
view of an exemplary embodiment of the bridge plug showing further details of
the
fluid passage.
[00028]
Figures 7A and 7B, also referred collectively as Figure 7, show
embodiments of a bridge plug and tractor assembly.
[00029] Figure
8 shows an embodiment of the bridge plug including one or more
sensors for measuring downhole conditions of the wellbore.
[00030]
Figures 9A and 9B illustrate an embodiment of the bridge plug including a
radio-active densitometer.
DETAILED DESCRIPTION
[00031] This
disclosure and the various features and advantageous details thereof
are explained more fully with reference to the non-limiting embodiments that
are
illustrated in the accompanying drawings and detailed in the following
description.
Descriptions of well-known starting materials, processing techniques,
components
and equipment are omitted so as not to unnecessarily obscure the disclosure in
detail.
Skilled artisans should understand, however, that the detailed description and
the
specific examples, while disclosing preferred embodiments, are given by way of
illustration only and not by way of limitation. Various substitutions,
modifications,
additions or rearrangements within the scope of the underlying inventive
concept(s)
will become apparent to those skilled in the art after reading this
disclosure.
Furthermore, any dimensions provided are provided by way of example and not
limitation.
[00032] Before
proceeding further, it should be noted that terms "uphole",
"downhole", "back", "front", "first", "second", "third", "last" are relative
terms, which
identify the position of an element with respect to the wellhead (surface),
i.e. are used
to refer to an element on or closer to the surface side (upwell side) relative
to a
corresponding feature that is farther from the wellhead (surface). For
example, an
"uphole" feature generally refers to the feature closer to the wellhead than
described
7
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports Docket:
PATFAM93-CA
and Real-Time Electronic Monitoring System
element. The terminology "uphole", "downhole" is also applicable to horizontal
wells.
Also, the terms "dart" and "plug" may be used interchangeable within this
description.
[00033] Figures
1A and 1B, illustrate schematic views of a fully cased/lined
wellbore, and an open hole wellbore, respectively, with a plurality of
deployed
downhole tools.
[00034] Figure
1A illustrates a schematic view of a wellbore system 100 deployed
in a cased wellbore 104. The wellbore system 100 includes a liner 102 that is
deployed
in the wellbore 104. In one embodiment, the liner 102 is referred to as a
casing. An
annulus 106 between the liner 102 and the wellbore 104 is cemented for
providing
support to the liner 102. The wellbore system 100 further includes downhole
tools 108
that are strategically deployed in the liner 102 where the formation is to be
stimulated.
Although, the Figure 1 illustrates only three downhole tools 108, it is
understood that
any number of downhole tools can be deployed based on fracking requirement of
the
wellbore 104.
[00035] Figure
1B shows the wellbore system 200 deployed in an open-hole
wellbore 202. The wellbore system 200 includes a tubing string 204, packers
206,
and multiple downhole tools 108. The packers 206 are placed around the tubing
string
204 in an annulus 202-1 formed between the tubing string 204 and an inner wall
of the
open-hole wellbore 202 for providing support to the tubing string 204. The
packers
206 also isolates different zones to be fractured. Based on the number of
zones to be
fractured, the tubing string 204 may include multiple stages. For instance,
the tubing
string 204 of Figure 1B is divided into three stages, and a downhole tool 108
is
deployed in each stage. Although the tubing string 204 shown in Fig. 1B is
divided
into three stages, it is understood that the tubing string 204 can be divided
into a much
larger number of stages, depending upon the length of the open-hole wellbore
202. In
the embodiment shown in Figure 1B, each downhole tool 108 has ports and a
sliding
sleeve enabled to open or close the ports to provide fluids access for a
respective
completion or production operation, such as a fracking operation. The ports,
when
opened, provide fluidic communication between an inner bore 110 of the tubing
string
204 and the portion of the annulus 202-1 isolated by two consecutive packers
206.
The ports in each downhole tool 108 are actuated by a bridge plug conveyed by
a
wireline not shown in Figure 1.
8
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00036] Figure
2 illustrates an embodiment of a bridge plug 302 deployable in the
tubing string 204 by a wireline 304. In this embodiment, the bridge plug 302
can be
pumped inside the tubing string 204 by fluid pressure. The bridge plug 302
includes
a body 310 that forms the housing of the bridge plug 302. The bridge plug 302
includes
a packing element 306, and keys 308 placed on an outer circumferential surface
of
the body 310. The packing element 306 may be provided towards the front or in
the
back of the body 310 with respect to the keys 308. The keys 308 are disposed
around
the body 310 and can assume an expanded state, when they protrude radially
from
the body 310 or a retracted state, when they are retracted inside the body 310
upon
application of a force (e.g., a hydraulic or an electric powered force).
Similarly, the
packing element 306 is adapted to retract (unset position) or expand radially
(set
position) to engage with the downhole tool 108 present in the tubing string
204. In one
embodiment, the bridge plug 302 includes a wireline connector (not shown)
attached
at the uphole end to receive at least one bridge plug control signal for
driving the
packer element into the set position and for releasing the one or more keys in
the
expanded state.
[00037] In one
implementation, the keys 308 are adapted to expand to engage a
shifting sleeve provided in a downhole tool 108. Once the bridge plug 302
engages
the downhole tool 108, hydraulic pressure is applied to the bridge plug 302 to
open
the port provided in the tubing string 204.
[00038]
Figures 3A and 3B show a sectional view of the downhole tool 108
depicting engagement of the bridge plug 302 with the downhole tool 108. In
this
embodiment, the downhole tool 108 is shown schematically as including a
sliding
sleeve 404 and a housing 408, the sleeve 404 being a port closure device that
can be
used by any tool for downhole operations. The housing 408 of downhole tool 108
includes a port 406 that is covered by the sliding sleeve 404 in Figures 3A
and 3B.
[00039] In the
embodiment of Figure 3A, the packing element 306 of the bridge
plug 302 is shown in the expanded state, where it grips the internal surface
410 of the
housing 408. In the embodiment of Figure 3B, the packing element 306 is also
shown
in the expanded state in this case gripping the internal surface 412 of the
sliding sleeve
404.
9
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00040] In
both embodiments, the sliding sleeve 404 has a shifting profile 402,
designed to engage the keys 308 of the bridge plug 302 when the keys 308 are
in the
expanded state. During engagement, as seen in Figure 3, the packing element
306
is set, and the keys 308 are expanded into the shifting profile 402 of sleeve
404.
[00041] The
actuation of the keys 308 to expand from the retracted state to the
expanded state is triggered by a plug actuation signal transmitted from
surface to the
bridge plug 302 over the wireline 304. Similarly, setting of the packing
element 306 is
activated in response to a packer actuation signal received from the surface
over the
wireline 304. The keys 308 and the packing element 306 may for example be
activated
by an electric motor 414 powered and controlled over the wireline 304. The
seals of
the packing element 306 may engage the respective internal wall 410 of the
housing
408 in Figure 3A, or the internal wall 412 of sleeve 404 in Figure 3B, by
swelling or by
a mechanical actuation.
[00042] Once
the packing element 306 engages the inner surface 412 of the
sleeve 404 in response to the packer actuation signal, the plug actuation
signal causes
the key to expand and hydraulic pressure is applied on the bridge plug 302.
This
causes the bridge plug 302 and the sliding sleeve 404, engaged by the bridge
plug
302, to move and open the ports 406. The open ports 406 enable tracking of the
wellbore 104.
[00043] The
operation of the bridge plug 302 is now described for a tracking
operation in connection with Figures 1 and 4. The bridge plug 302 can operate
in
different modes and can be operated to stimulate either one zone or multiple
zones of
the wellbore 104. Accordingly, such modes of operation are termed as a single-
point
entry mode or a multi-point entry mode.
[00044] In the
single-point entry mode, the bridge plug 302 is deployed towards a
downhole tool 108 of interest in the tubing string 204.Further, a depth up to
which the
bridge plug is deployed is based on the distance of that tool from the surface
measured
as a length of the wireline 304 deployed in the wellbore 104 or 202. For
example, let
us assume that the first stage is stage 114 shown in Figure 1. Once the bridge
plug
302 arrives at the first stage 114, the packing element 306 of the bridge plug
302 is
CA 3002327 2018-04-23
Title: Fracking System with VVireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
activated. The keys 308 of the bridge plug 302 are then actuated by to expand
and
engage the shifting profile 402 of the sleeve 404. The setting of the packing
element
306 and the expansion of the keys 308 are controlled with bridge plug control
signals
received via the wireline 304. In one embodiment, the packing element 306 is
controlled with a first bridge control signal received via the wireline 304,
and the keys
308 are controlled with a second bridge control signal received via the
wireline 304.
Thereafter, pressure is applied to the bridge plug 302 to open the port 406 of
the first
stage 114. Figure 4 illustrates the situation when the bridge plug 302,
engaged with
the port closure (sleeve) 404, moved the sleeve 404 from the port covering
position
shown in Figures 3A and 3B, to a port open position.
[00045] Next,
a tracking fluid is pumped from the surface of the wellbore through
the tubing string 204 for tracking the first stage 114 of the wellbore 104,
while the
bridge plug 302 blocks the fluid flow to stages downhole from the first stage
114. The
first stage 114 is tracked by the fluid exiting under pressure through the
open ports of
the downhole tool 108, as shown at 502 in Figure 4. Thereafter, the bridge
plug 302
is released from the first downhole tool by retracting the keys 308 and
disengaging the
packing element 306 and is moved to the next stage to be treated, referred to
here as
the second stage 116, which is uphole from the first stage. In one embodiment,
the
keys 308 and the packing element 306 are disengaged upon receiving a third
bridge
plug signal via the wireline 304. The retracted state of the keys 308 and the
un-set
position of the packing element are also preferable prompted by bridge plug
control
signals received via the wireline 304. The operation is repeated for the third
stage, and
any other stages that need to be tracked.
[00046] In the
multi-point entry mode, the bridge plug 302 is deployed in a first
stage 114 of the tubing string 204, to seal the wellbore 104 by setting the
packing
element 306. The plug engages the sleeve 404 to open the ports 406 as in the
single
point entry mode. However, instead of fracking the first stage 114, once the
port 406
of the first stage 114 was opened, the bridge plug 302 is released from the
sleeve 404
of the first stage 114, moved to the second stage 116 and operated to open the
ports
406 of the second stage 116. The operation is repeated for the desired number
of
stages.
11
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00047] In
this embodiment, after the bridge plug 302 opens the ports of the last
stage of interest, let us assume that is stage 118, the packing element 306 is
disengaged from sealing the wellbore 104. Fracking starts with the first stage
114
(most downhole stage of the series of stages to be fracked) stage. Thus, the
bridge
plug 302 is moved to the first stage 114 and actuated to block the fluid flow
beyond
the stage in the downhole direction and to engage with the sleeve 404.
Thereafter,
fracking fluid is pumped from the surface of the wellbore 104 through the
tubing string
204 for fracking the all the stages of the wellbore 104 that have the ports
open, while
the bridge plug 302 blocks the fluid flow to further downhole (i.e., beyond
the last stage
in the tubing string 204). In this mode of operation, the ports can utilize a
flow restriction
to create a limited entry of fluid into the formation. The fluid is pumped
into the tubing
string 204 with high pressure for creating fractures 502 in the wellbore 104
as shown
in Fig. 4.
[00048]
Following completion of the fracture treatment, the pressure in the fracked
stages starts to bleed off. Since the bridge plug 302 isolates the uphole
portion 504
of the tubing string 204 from the downhole portion 506 of the tubing string
204, when
fracking the next zone uphole from the bridge plug 302 starts, a very high-
pressure
differential may be created across the two ends of the bridge plug 302. Such a
large
differential pressure may result in the disengagement of the bridge plug 302
from the
sleeve 404. This can be a volatile and unstable situation, that if not
addressed, can
result in the bridge plug accidentally being blown downhole, also causing
snapping of
the wireline 304. As well, this pressure differential can make it impossible
to release
the bridge plug for redeployment for treating the next stages, because of the
massive
amounts of pressure acting in the downhole direction that would need to be
controlled
before disengaging the bridge plug for further shifting uphole.
[00049]
Consequently, this large differential pressure needs to be equalized to
avoid damaging the bridge plug 302 and wireline 304. The embodiments shown in
Figures 5A-5C and 6A-6C describe surge prevention solutions to address this
pressure differential problem.
[00050] One
solution, shown in Figures 5A-5C, is to provide the bridge plug 302
with an openable fluid passage 602 inside the body 310 to selectively allow
equalization of pressure. Figures 5A-5C show a view of the bridge plug 302
having
12
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
an equalization valve 610 provided through the body 310 of the bridge plug 302
with
a view to equalize a high pressure in the tubing string 204. In these figures,
the valve
is shown symbolically at 610 and may be open for pressure equalisation, or
closed,
as needed. The opening of the valve 610 can be triggered by an electrical
signal sent
from surface via wireline 304 to the bridge plug 302.
[00051] In the
embodiment shown in Figure 5A the bridge plug 302 is in the set
position (expanded), sealing the stages downhole from the bridge plug 302. In
the set
position, the packing element 306 is engaged with the tool of interest, also
referred to
as the target tool. The keys 308 are in the expanded state, in engagement with
the
shifting profile 402 of the sleeve 404. After fracking operation, the valve
610 in the
bridge plug 302 is triggered to open the fluid-passage 602 to equalize the
pressure
between the uphole side 604 and downhole side 606. As seen in Figure 5B, the
fluid
is allowed to flow from the uphole side 604 to the downhole side 606. It is
also
desirable to monitor the pressure differential to identity when the
equalization has
occurred. This can be performed using pressure monitoring sensors in the
bridge plug
302, adapted to measure pressure communicate the measurements to the surface
using wireline 304. The monitored data is used to trigger the valve 610 to
open or
close through the wireline 304. The operation of the valve 610 and measurement
system for monitoring pressure is described later in connection with Figure 8.
[00052] The
valve 610 may be opened in a variety of manners including techniques
used to open valves in retrievable packers. For example, If the packing
element 306
is a mechanical packing element, the valve 610 can be open by rotating the
bridge
plug 302. In another example, the valve 610 can be triggered by an electrical
signal
sent from the surface via wireline 304 to the bridge plug 302. After, the
pressure is
equalized above and below the bridge plug 302, the packing element 306 can be
released as shown in Figure 5C. Here, the packing element 306 is released,
shown
by its diameter becoming smaller. Also, the keys 308 are shown as retracted
from the
previously expanded state shown in Figure 5B.
[00053]
Figures 6A to 6C show a sectional view of an exemplary embodiment of
the bridge plug 302 with the valve 610 in some details. In this example, the
valve 610
include a valve body 704 and an internal seal 706. The valve 602 is placed in
the
fluid-passage 602 formed throughout the bridge plug 302, as discussed in
connection
13
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
with Figures 5A-5C. In the embodiment of Figure 6A, the valve 610 is closed,
as the
internal seal 706 is caught, for example, a bore 710 formed in an inner wall
708 of
body 310 of the bridge plug 302. No fluid can pass through the fluid passage
602 past
the internal seal 706.
[00054] When
the valve 610 is open, the internal seal 706 is moved out of the bore
710, opening the fluid passage 602. For example, the internal seal 706 may be
moved
towards downhole direction until the internal seal 706 disengage from the
inner wall
708 of the bridge plug 302. Thereafter, the fluid is allowed to flow through
the fluid-
passage 602 as shown in Fig. 6B. After the pressure of fluid is equalized
between
the uphole and downhole sides of the bridge plug 302, the bridge plug 302 is
released
from the sleeve/inner wall of the downhole tool 108 of the current stage, and
the keys
308 are retracted from the profile 402, and as shown in Figure 6C.
[00055] In
some embodiments, the bridge plug 302 may include motion dampers
to prevent sudden motion of the bridge plug caused by pressure surges. Such
motion
dampers may also assume a retracted state or an expanded state. The dampers
may
be deployed by sending a signal to the bridge plug 302 over the wireline 304
or may
be deployed automatically under the influence of a centrifugal force. An
exemplary
implementation of the such motion dampers is explained with respect to Figures
7A
and 7B.
[00056]
Figures 7A and 7B show an embodiment of the bridge plug 302 with
motion dampers, such tractor 804 including tracked wheels 802 attached to the
bridge
plug 302. In one implementation, the wheels 802 are disposed around the bridge
plug
302. The wheels 802 are retractable and adapted to engage and disengage with
the
inner wall of the tubing string 204, to control movements of the bridge plug
302. The
wheels 802 may be actuated to engage the inner wall of the tubing string 204
by an
electrical motor controlled from the surface, or autonomously.
[00057] Thus,
the wheels 802 may be activated (i.e., expanded or retracted) by an
electrical motor controlled by a signal provided from the surface via wireline
304. In
this embodiment, the bridge plug 302 is initially pumped in the tubing string
204 with
the wheels 802 in the retracted state. The wheels 802 are deployed after the
tractor
control signal is communicated from the surface through the wireline 304. The
14
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
resulting friction between the wheels 802 and the inner wall of the tubing
string 204
will reduce/dampen the speed of the bridge plug.
[00058]
Autonomous deployment of the wheels 802 may be triggered by the
centrifugal force or by the speed of the plug in the tubing string 204. For
example, the
centrifugal force generated when the bridge plug spins in the tubing string,
may be
used to trigger expansion of the wheels 802 from the retraced position, so
that the
centrifugal force is rapidly transferred to the inside surface of the tubing
string 204 thus
increasing friction between the wheels 802 and the inside of tubing string
thus
controlling the spinning of the plug.
[00059] The
wheels 802 may also deploy automatically when the uphole speed of
the bridge plug 302 exceeds a predetermined threshold. In one example, the
threshold speed of the bridge plug 302 is 1 m/s. In one embodiment, surface of
the
wheels 802 are made of rubber or a milled metal, and the contact surface of
the wheels
can be 1/2 an inch wide.
[00060] In an
alternative embodiment, the wheels 802 can be attached to the
tractor 804 attached to the bridge plug 302 as shown in Figure 7A. The tractor
804 is
connected to the bridge plug 302 by any known means. The tractor 804 is
powered
by an electrical current through the wireline 304 and can be moved in both
directions
in the tubing string 204. Displacement of the tractor 804 inside the tubing
string is
controlled by tractor control signals received over the wireline 304. In this
embodiment
movement of the bridge plug 302, which is connected to the tractor 804, is
attenuated
and controlled by the tractor 804. In another embodiment, the tractor 804 can
be
integrated into the bridge plug 302. The tractor 804 limits uncontrolled
downhole
movement, as well as uphole movement of the bridge plug 302 in the tubing
string
204.
[00061] The
bridge plug 302 can also be used to measure downhole conditions,
such as temperature, pressure, sand concentration, etc. in real time. In one
example,
the bridge plug 302 may include an array of sensors to monitor downhole
conditions.
An exemplary implementation of the such monitoring is explained with respect
to
Figure 8.
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00062] Figure
8 illustrates an embodiment of the bridge plug 302 including one or
more sensors 902, 904. The one or more sensors 902 may include, but are not
limited
to, a pressure sensor, a densitometer, an acoustic sensor, and a temperature
sensor.
In the illustrated embodiment, the sensors can be coupled to the bridge plug
302 at
the uphole end of the plug, as shown by sensors 902, and at the downhole end
of the
bridge plug 302, as shown by sensors 904. The terms "uphole end" and "downhole
end" of the bridge plug refer here to the placement of the sensors when the
plug is run
into the wellbore. Preferably, pressure and temperature sensors may be placed
at
both the uphole and downhole ends to measure these parameter in the uphole
portion
504 and downhole portion 506, shown on Figure 4. Listening devices may also be
provided at any or both uphole and downhole ends. A radioactive densimeter is
preferably placed at the uphole end. It is to be mentioned that other types of
sensors
902, 904 may be used, the above types of sensors were indicated by way of
example.
[00063] The
sensors 902, 904 sense the downhole parameters of interest and
communicate to the surface of the wellbore system 100 via wireline 304 or
wirelessly
(the wireless mode is not illustrated). For instance, the pressure sensor
measures
real-time pressure at the bridge plug 302 near a fracking or production port.
In another
example, the temperature sensor measures temperature readings of fracking
fluid
near the bridge plug 302, and communicates the measured reading to the
surface. In
one embodiment, the measured temperature reading indicates how rapidly the
fluid is
circulating from the surface (where the water might be heated) to the downhole
location of the bridge plug 302. In another example, the acoustic sensor
measures
acoustic readings that denotes geological fracture events such as the merger
of two
separately initiated fracks, or equipment breakdown events, and communicate to
the
surface. In another example, the densitometer measures concentration of sand
near
the bridge plug 302 and communicates the measurement to the surface.
[00064]
Generally, the fluid for fracking the wellbore 104 includes proppant that
enables fracking operations. The proppant mixed with the fluid is pumped
through the
tubing string 204. A radio-active densitometer sensor can be used to detect
over-
displacement and screen-out by measuring the density of the slurry generated
during
fracking the wellbore 104 using radiation measurements.
16
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
[00065] In one
embodiment, the radio-active densitometer may be used to
measure concentration of the sand near the bridge plug 302. The radio-active
densitometer may also detect sand-laden fluid at the bridge plug 302 as shown
in
Figure 9A, and report to surface via the wireline 304. The radio-active
densitometer
sends information to the surface about screen out and over displacement
conditions
with complete location and timing information, just as either condition begins
to
materialize. Figure 9A shows the sand concentration at the bridge plug 302 is
high,
so the pumping of proppant is stopped or reduced, thus, the screen out and
over
displacement conditions are avoided. Figure 9B shows the sand concentration at
the
bridge plug 302 is low after halting the pumping of proppant.
[00066] The
readings are communicated to the surface and if the concentration of
the sand crosses a threshold value, pumping of proppant is stopped to avoid
displacement of the proppant. For example, if a sand concentration of
4lbs/gallon is
suddenly detected by the radio-densitometer near the bridge plug 302, a signal
is
communicated to the surface via the wireline 304 in real time, and pumping of
proppant
is reduced or suspended to avoid over-displacement. Furthermore, in response
to this
reading, the operator can cause the bridge plug 302 to be moved uphole from
this high
sand concentration zone based on the measured sand concentration, and another
stage of the wellbore with lower sand concentrations can be operated upon.
Screen-
out conditions that are very costly can thus be avoided through such real-time
detection, communication to surface, and remediation, of conditions around the
bridge
plug 302.
[00067] The
densitometer can also provide useful information that can be used to
detect not only screen-out and over-displacement, but also other problematic
conditions by detecting the presence of radioactive tracers near the bridge
plug 302,
that are originally inserted in the fluid before pumped into the tubing string
204 from
the surface. Further, the radioactive tracers measurements may be associated
with a
certain location in the casing/wellbore at which the tracers were detected.
[00068] As
used herein, the terms "comprises," "comprising," "includes,"
"including," "has," "having" or any other variation thereof, are intended to
cover a non-
exclusive inclusion. For example, a process, product, article, or apparatus
that
comprises a list of elements is not necessarily limited only to those elements
but may
17
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
include other elements not expressly listed or inherent to such process,
product,
article, or apparatus. Further, unless expressly stated to the contrary, "or"
refers to an
inclusive or and not to an exclusive or. For example, a condition A or B is
satisfied by
any one of the following: A is true (or present) and B is false (or not
present), A is false
(or not present) and B is true (or present), and both A and B are true (or
present).
[00069]
Additionally, any examples or illustrations given herein (including in any
Appendix) are not to be regarded in any way as restrictions on, limits to, or
express
definitions of, any term or terms with which they are utilized. Instead, these
examples
or illustrations are to be regarded as being described with respect to one
particular
embodiment and as illustrative only. Those of ordinary skill in the art will
appreciate
that any term or terms with which these examples or illustrations are utilized
will
encompass other embodiments which may or may not be given therewith or
elsewhere
in the specification and all such embodiments are intended to be included
within the
scope of that term or terms. Language designating such nonlimiting examples
and
illustrations includes, but is not limited to: "for example," "for instance,"
"e.g.," "in one
embodiment."
[00070]
Benefits, other advantages, and solutions to problems have been
described above with regard to specific embodiments. However, the benefits,
advantages, solutions to problems, and any component(s) that may cause any
benefit,
advantage, or solution to occur or become more pronounced are not to be
construed
as a critical, required, or essential feature or component.
[00071]
Reference throughout this specification to "one embodiment", "an
embodiment", or "a specific embodiment" or similar terminology means that a
particular feature, structure, or characteristic described in connection with
the
embodiment is included in at least one embodiment and may not necessarily be
present in all embodiments. Thus, respective appearances of the phrases "in
one
embodiment", "in an embodiment", or "in a specific embodiment" or similar
terminology
in various places throughout this specification are not necessarily referring
to the same
embodiment. Furthermore, the particular features, structures, or
characteristics of any
particular embodiment may be combined in any suitable manner with one or more
other embodiments. It is to be understood that other variations and
modifications of
18
CA 3002327 2018-04-23
Title: Fracking System with Wireline Shifted Ports
Docket: PATFAM93-CA
and Real-Time Electronic Monitoring System
the embodiments described and illustrated herein are possible in light of the
teachings
herein and are to be considered as part of the spirit and scope of the
invention.
[00072] In the
description herein, numerous specific details are provided, such as
examples of components and/or methods, to provide a thorough understanding of
embodiments of the invention. One skilled in the relevant art will recognize,
however,
that an embodiment may be able to be practiced without one or more of the
specific
details, or with other apparatus, systems, assemblies, methods, components,
materials, parts, and/or the like. In
other instances, well-known structures,
components, systems, materials, or operations are not specifically shown or
described
in detail to avoid obscuring aspects of embodiments of the invention. While
the
invention may be illustrated by using a particular embodiment, this is not and
does not
limit the invention to any particular embodiment and a person of ordinary
skill in the
art will recognize that additional embodiments are readily understandable and
are a
part of this invention.
[00073]
Although the invention has been described with respect to specific
embodiments thereof, these embodiments are merely illustrative, and not
restrictive of
the invention. Rather, the description is intended to describe illustrative
embodiments,
features and functions in order to provide a person of ordinary skill in the
art context
to understand the invention without limiting the invention to any particularly
described
embodiment, feature or function. While specific embodiments of, and examples
for,
the invention are described herein for illustrative purposes only, various
equivalent
modifications are possible within the spirit and scope of the invention, as
those skilled
in the relevant art will recognize and appreciate. As indicated, these
modifications
may be made to the invention in light of the foregoing description of
illustrated
embodiments of the invention and are to be included within the spirit and
scope of the
invention. Thus, while the invention has been described herein with reference
to
particular embodiments thereof, a latitude of modification, various changes
and
substitutions are intended in the foregoing disclosures, and it will be
appreciated that
in some instances some features of embodiments of the invention will be
employed
without a corresponding use of other features without departing from the scope
and
spirit of the invention as set forth. Therefore, many modifications may be
made to
adapt a particular situation or material to the essential scope and spirit of
the invention.
19
CA 3002327 2018-04-23
