U.S. patent application number 14/935114 was filed with the patent office on 2016-05-12 for destructible frac-ball and device and method for use therewith.
The applicant listed for this patent is Ensign-Bickford Aerospace & Defense Company. Invention is credited to Alan J. Garvey, Marc A. Morris.
Application Number | 20160130906 14/935114 |
Document ID | / |
Family ID | 55911838 |
Filed Date | 2016-05-12 |
United States Patent
Application |
20160130906 |
Kind Code |
A1 |
Garvey; Alan J. ; et
al. |
May 12, 2016 |
DESTRUCTIBLE FRAC-BALL AND DEVICE AND METHOD FOR USE THEREWITH
Abstract
A destructible frac-ball is provided that includes a body and a
rupture mechanism, and a method for selectively initiating fluid
flow within a casing segment is provided that utilizes one or more
of the aforesaid frac-balls. The rupture mechanism is in
communication with the body, and is operable to selectively
initiate and break the body into the plurality of discrete
pieces.
Inventors: |
Garvey; Alan J.; (Suffield,
CT) ; Morris; Marc A.; (Clarksville, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ensign-Bickford Aerospace & Defense Company |
Simsbury |
CT |
US |
|
|
Family ID: |
55911838 |
Appl. No.: |
14/935114 |
Filed: |
November 6, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62076934 |
Nov 7, 2014 |
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Current U.S.
Class: |
166/376 ;
166/193; 166/66 |
Current CPC
Class: |
E21B 33/12 20130101;
E21B 34/063 20130101; E21B 34/14 20130101; E21B 43/26 20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 47/18 20060101 E21B047/18; E21B 47/14 20060101
E21B047/14; E21B 47/06 20060101 E21B047/06; E21B 47/12 20060101
E21B047/12 |
Claims
1. A frac-ball, comprising: a body; a rupture mechanism in
communication with the body, which rupture mechanism is operable to
selectively initiate and break the body into the plurality of
discrete pieces.
2. The frac-ball of claim 1, wherein the body includes a core
encased within a shell.
3. The frac-ball of claim 2, wherein the core comprises a fluid
soluble material.
4. The frac-ball of claim 3, wherein the shell comprises a fluid
non-soluble material.
5. The frac-ball of claim 2, wherein the shell comprises a fluid
soluble material.
6. The frac-ball of claim 2, wherein the rupture mechanism includes
an energetic material.
7. The frac-ball of claim 2, wherein the core comprises a
fluid.
8. The frac-ball of claim 1, wherein the body is a solid body
substantially consisting of a homogeneous material.
9. The frac-ball of claim 8, wherein the homogeneous material is a
fluid soluble material.
10. The frac-ball of claim 1, wherein the rupture mechanism
includes a trigger mechanism having a sensor, and the trigger
mechanism is operable to cause the rupture mechanism to initiate
based on input from the sensor.
11. The frac-ball of claim 10, wherein the sensor is operable to
sense at least one of pressure, temperature, or conductivity
proximate the frac-ball.
12. The frac-ball of claim 10, wherein the sensor is operable to
sense at least one of magnetic, electromagnetic, pressure,
electrical, RF, or ultrasonic signals.
13. The frac-ball of claim 1, wherein the rupture mechanism
includes a trigger mechanism that includes a timer.
14. The frac-ball of claim 1, wherein the rupture mechanism
includes a trigger mechanism that includes a first metallic alloy
and a second metallic alloy, wherein the first metallic alloy has a
first melting temperature and the second metallic alloy has a
second melting temperature, which second melting temperature is
higher than the first melting temperature, and wherein the first
metallic alloy and the second metallic alloy are exothermically
reactive with one another.
15. The frac-ball of claim 1, wherein the rupture mechanism
includes a receiver operable to receive at least one of a radio
frequency energy type signal, or an acoustic energy type signal, an
electrical energy type signal, or a pressure pulse type signal.
16. The frac-ball of claim 1, wherein the rupture mechanism
includes a trigger mechanism that is operable to be selectively
deployed into a state where it may be activated to selectively
cause the rupture mechanism to initiate and break the body into the
plurality of discrete pieces.
17. The frac-ball of claim 1, wherein the rupture mechanism
includes a trigger mechanism that is operable to be selectively
activated via electromagnetic inductive coupling.
18. The frac-ball of claim 1, further comprising a safety inhibit
operable to prevent the rupture mechanism from initiating and
breaking the body into the plurality of discrete pieces unless a
predetermined condition is met.
19. A segmentation device for use within a casing, comprising: a
seat for receiving a frac-ball; at least one rupture mechanism
disposed relative to the seat, which rupture mechanism is operable
to act upon a frac-ball disposed within the seat and cause the
frac-ball to rupture into discrete pieces.
20. The segmentation device of claim 19, wherein the rupture
mechanism includes a mechanical feature operable to strike the
frac-ball and thereby cause the frac-ball to rupture into the
discrete pieces.
21. A method for selectively initiating fluid flow within a casing
segment, comprising: providing a segmentation device operable to be
disposed within the casing, which segmentation device includes a
seat for receiving a frac-ball; providing a frac-ball having a body
and a rupture mechanism in communication with the body, which
rupture mechanism includes a trigger mechanism operable to
selectively cause the rupture mechanism to initiate and break the
body into the plurality of discrete pieces; causing the rupture
mechanism to initiate and break the frac-ball body into the
plurality of discrete pieces based on input from the trigger
mechanism, and thereby selectively initiating fluid flow through
the segmentation device.
Description
[0001] This application claims priority to U.S. Patent Appin. No.
62/076,934 filed Nov. 7, 2014, which document is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present disclosure relates to subterranean well casing
segmentation devices in general, and to frac-balls used with casing
segmentation devices in particular.
[0004] 2. Background Information
[0005] Subterranean wells can be used to locate and extract
subterranean disposed raw materials. For example, wells may be used
to locate and extract hydrocarbon materials (e.g., hydrocarbon
fluids such as oil, and gases such as natural gas) from
subterranean deposits. A water well may be used for locating and
extracting potable or non-potable water from an underground water
table. A well configured and located to locate and extract
hydrocarbon materials typically includes a tubular casing disposed
subsurface within the well, and pumping system for injecting
materials into and for extracting materials out of the well. The
casing may be oriented to have vertically disposed sections,
horizontally disposed sections, and sections having a combined
vertical and horizontal orientation.
[0006] The term "hydraulic fracturing" refers to well formation
techniques (sometimes referred to as "well completion" techniques)
that create fractures within the subterranean ground to facilitate
extraction of hydrocarbon materials disposed within the
subterranean ground. There are several hydraulic fracturing
techniques currently used, including techniques that utilize fluid
flow segmentation devices.
[0007] For example, "plug and perforation" techniques may utilize
one or more plugs (a type of casing segmentation device) that are
positionable within the well casing. The plugs are used to
fluidically isolate (i.e., segment) casing sections for a variety
of reasons; e.g., to permit specific casing sections to be radially
perforated, etc. The perforations in the casing provide fluid paths
for materials to selectively exit and enter a fluid passage within
the casing. In some instances, the plugs are designed to include a
fluid flow passage that permits fluid flow through the plug; i.e.,
between a forward end of the plug and an aft end of the plug. The
passage has a ball seat disposed at the forward end of the passage.
The term "forward end" refers to the end of the passage disposed
closest to the well head when disposed within the casing, and the
term "aft end" refers to the end of the passage disposed farthest
from the well head when disposed within the casing. The passage
ball seat is configured to receive a spherical ball (typically
referred to as a "frac-ball"). To segment the well casing, a
frac-ball is introduced into the casing and the frac-ball is
carried with fluid flow until it reaches the ball seat. Once the
frac-ball is seated properly within the seat, the frac-ball closes
the plug fluid passage and prevents fluid passage through the plug.
The fluid on one side of the plug may then be increased
dramatically in pressure; e.g., to perform the
perforation/fracturing process. Subsequently, the frac-ball and
plug may be machined out to remove the isolating structure, or the
frac-ball may be of a type that dissolves to permit fluid flow
through the plug. There are several disadvantages associated with
frac-balls that must be machined out or dissolved; e.g., cost and
time.
[0008] Another hydraulic fracturing technique utilizes a sliding
sleeve type device (another type of casing segmentation device). In
this approach, the casing typically includes multiple stages (e.g.,
each with a sliding sleeve assembly and a packer assembly) that are
built into the casing. Each sliding sleeve assembly includes an
inner component and an outer component, and the inner component may
be biased to reside in a forward located closed position. The inner
component includes a fluid flow passage that permits fluid flow
through the sliding sleeve; e.g., between a forward end of the
inner component and an aft end of the inner component. The passage
has a ball seat disposed at the forward end of the passage. When a
frac-ball is properly seated within the seat and sufficient
pressure is created on the frac-ball side of the sliding sleeve,
the inner component will travel axially aft ward relative to the
outer component. The axial travel allows pressurized fluid to
perforate the casing and create the fractured subterranean
structure. The frac-balls used to activate the sliding sleeves (and
the associated frac-ball seat) may be arranged in a particular
order for use in the casing; i.e., the smallest diameter frac-ball
is introduced into the casing first and passes through the sliding
sleeves having progressively smaller diameter seats until it
reaches a seat that it cannot pass through and is consequently
seated, thereby closing the fluid passage through the sliding
sleeve. Each progressively larger frac-ball is introduced and the
process is repeated until all the zones are fractured. Once the
high pressure source is removed, it may be possible to use
subterranean fluids entering the casing to unseat the frac-balls.
In some instances, however, it may be necessary to remove the
frac-balls via machining or dissolution. Sliding sleeve
arrangements are not appropriate for all applications, and as
indicated above there are disadvantages to frac-ball machining and
dissolution should it be necessary to clear the casing.
SUMMARY OF THE DISCLOSURE
[0009] According to an aspect of the present disclosure, a
destructible frac-ball is provided that includes a body and a
rupture mechanism. The rupture mechanism is in communication with
the body, and is operable to selectively initiate and break the
body into the plurality of discrete pieces.
[0010] According to another aspect of the present disclosure, a
segmentation device is provided for use within a casing. The
segmentation device includes a seat for receiving a frac-ball, and
at least one rupture mechanism disposed relative to the seat. The
rupture mechanism is operable to act upon a frac-ball disposed
within the seat and cause the frac-ball to rupture into discrete
pieces.
[0011] According to another aspect of the present disclosure, a
method for selectively initiating fluid flow within a casing
segment is provided. The method includes the steps of: a) providing
a segmentation device operable to be disposed within the casing,
which segmentation device includes a seat for receiving a
frac-ball; b) providing a frac-ball having a body and a rupture
mechanism in communication with the body, which rupture mechanism
includes a trigger mechanism operable to selectively cause the
rupture mechanism to initiate and break the body into the plurality
of discrete pieces; and c) causing the rupture mechanism to
initiate and break the frac-ball body into the plurality of
discrete pieces based on input from the trigger mechanism, and
thereby selectively initiating fluid flow through the segmentation
device.
[0012] In a further embodiment of any of the foregoing aspects, the
frac-ball body may include a core encased within a shell.
[0013] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball core may include a fluid soluble
material.
[0014] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball shell may include a fluid non-soluble
material or a fluid soluble material.
[0015] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include an
energetic material.
[0016] In a further embodiment of applicable foregoing aspects and
embodiments, the frac-ball body may be a solid body substantially
consisting of a homogeneous material, which homogeneous material
may be a fluid soluble material.
[0017] In a further embodiment of any of the foregoing aspects and
embodiments, frac-ball rupture mechanism may include a trigger
mechanism having a sensor, and the trigger mechanism is operable to
cause the rupture mechanism to initiate based on input from the
sensor. The sensor may be operable to sense at least one of
pressure, temperature, or conductivity proximate the frac-ball.
Alternatively, the sensor may be operable to sense at least one of
magnetic, electromagnetic, pressure, electrical, RF, or ultrasonic
signals.
[0018] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include a trigger
mechanism that includes a timer.
[0019] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include a trigger
mechanism that includes a first metallic alloy and a second
metallic alloy, wherein the first metallic alloy has a first
melting temperature and the second metallic alloy has a second
melting temperature, which second melting temperature is higher
than the first melting temperature, and wherein the first metallic
alloy and the second metallic alloy are exothermically reactive
with one another.
[0020] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include a receiver
operable to receive at least one of a radio frequency energy type
signal, or an acoustic energy type signal, an electrical energy
type signal, or a pressure pulse type signal.
[0021] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include a trigger
mechanism that is operable to be selectively deployed into a state
where it may be activated to selectively cause the rupture
mechanism to initiate and break the body into the plurality of
discrete pieces.
[0022] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball rupture mechanism may include a trigger
mechanism that is operable to be selectively activated via
electromagnetic inductive coupling.
[0023] In a further embodiment of any of the foregoing aspects and
embodiments, the frac-ball may include a safety inhibit operable to
prevent the rupture mechanism from initiating and breaking the body
into the plurality of discrete pieces unless a predetermined
condition is met.
[0024] The foregoing features and the operation of the invention
will become more apparent in light of the following description and
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a sectional diagrammatic illustration of a portion
of a well casing.
[0026] FIG. 2 is a diagrammatic illustration of a sliding sleeve
type casing segmentation device shown in a closed
configuration.
[0027] FIG. 3 is a diagrammatic illustration of a sliding sleeve
type casing segmentation device shown in an open configuration.
[0028] FIG. 4 is a diagrammatic illustration of the casing
segmentation device.
[0029] FIG. 5 is a diagrammatic illustration of a frac-ball
embodiment.
[0030] FIG. 6 is a diagrammatic illustration of a ruptured
frac-ball, shown in discrete pieces.
[0031] FIG. 7 is a sectional diagrammatic illustration of a
frac-ball embodiment.
[0032] FIG. 8 is a sectional diagrammatic illustration of a
frac-ball embodiment, including a rupture mechanism embodiment.
[0033] FIG. 9 is a sectional diagrammatic illustration of a
frac-ball embodiment, including a rupture mechanism embodiment.
[0034] FIG. 10 is a sectional diagrammatic illustration of a
frac-ball embodiment, including a rupture mechanism embodiment.
[0035] FIG. 11 is a diagrammatic illustration of a frac-ball
embodiment.
[0036] FIG. 12 is a sectional diagrammatic illustration of a
frac-ball embodiment, including a rupture mechanism embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0037] Now referring to FIG. 1, an exemplary embodiment of a
wellbore 20 disposed in a subterranean formation is shown. The
wellbore 20 includes a fluid conduit (typically referred to as a
"casing"; e.g., casing 22) disposed within a drilled bore extending
below surface level 24. The wellbore 20 is diagrammatically shown
as having a substantially vertical oriented section 26, a
substantially horizontal oriented section 28, and an arcuate
section 30 connecting the vertical and horizontal sections 26, 28.
For purposes of describing aspects of the present disclosure, the
casing 22 is described herein as including casing segmentation
devices 32, packers 34, and pipe sections 36. The pipe sections 36
include a wall 38 surrounding a flow passage 40. The described well
casing configuration reflects a typical configuration and the
present disclosure is not limited to any particular well casing
configuration. The casing 22 is disposed within the well after the
well is drilled. The wellbore 20 is shown as having cement 42
disposed between the outer diameter of the casing 22 and the inner
diameter of the drilled bore, which cement 42 secures the casing 22
within the drilled bore. Not all wellbores include cement or other
material disposed outside of the casing 22.
[0038] As indicated above, a well completion process that utilizes
hydraulic fracturing involves creating fractures 44 (e.g.,
cavities) within the subterranean ground adjacent the casing 22 to
facilitate extraction of hydrocarbon materials (or water) disposed
within the subterranean ground. The fracturing process is typically
performed in segments (sometimes referred to as "stages"); e.g., a
first segment of the casing 22 may be created adjacent the portion
of the wellbore 20 furthest from the wellhead 46, and the casing 22
in that segment "perforated" to create a fluid path between the
casing flow passage 40 and the subterranean environment adjacent
the segment. Once the first segment is fractured, that segment may
be isolated, and the process may be repeated for the next segment
in line, until the all of the desired segments of the wellbore 20
are fractured. The term "perforated", as used herein, refers to the
creation of the aforesaid fluid paths between the casing flow
passage 40 and the subterranean environment adjacent the segment.
In some instances, a pipe section 36 of the casing 22 is perforated
by creating holes in the wall 38 of the pipe section 36 (e.g.,
using a perforating gun). In other instances, a casing section may
be "perforated" by manipulating a sliding sleeve 48 (e.g., see
FIGS. 2 and 3) or other valve-type casing segmentation device 32
into an open configuration, wherein apertures 50 in the sliding
sleeve 48 are exposed to create the fluid paths between the casing
flow passage and the subterranean environment adjacent the segment.
FIG. 2 diagrammatically illustrates a sliding sleeve type casing
segmentation device 32 disposed in a closed configuration; e.g.,
preventing fluid flow radially through the casing. FIG. 3
illustrates a sliding sleeve type casing segmentation device 32
disposed in an open configuration; e.g., allowing radial fluid flow
through the casing via apertures 50. The present disclosure is not
limited to use with any particular device or method for creating
the fractures within the subterranean environment.
[0039] Aspects of the present disclosure include destructible
frac-balls 52, casing segmentation devices 32 that are configured
for use with destructible frac-balls 52, and methods for completing
a well using destructible frac-balls 52. The present disclosure is
not limited to use with any particular type casing device that uses
a frac-ball 52. In addition, the present disclosure is described
herein in the context of a well formed to extract hydrocarbon based
materials. The present disclosure is not limited to applications
for extracting hydrocarbon based materials; e.g., oils and
gases.
[0040] Referring to FIG. 4, the casing segmentation devices 32
(e.g., sliding sleeves, plugs, etc.) are designed to be
positionally located within the casing 22. These devices 32 may
include an internal passage 54 with a forward end 56, and aft end
58, and a ball seat 60 disposed at the forward end. Once a
frac-ball 52 is seated properly within the ball seat 60, the
frac-ball 52 closes the fluid passage 54 and prevents fluid passage
there through.
[0041] Referring to FIGS. 5 and 6, according to an aspect of the
present disclosure a destructible frac-ball 52 is provided. The
destructible frac-ball 52 is adapted to be selectively ruptured
into a plurality of discrete pieces (e.g., depicted in FIG. 6 as
pieces 52a, 52b, 52c, 52d, 52e, 52f, 52g, etc.), with each discrete
piece smaller in volume than the frac-ball 52. At the time of
rupture, or some time thereafter, each discrete frac-ball piece is
of a size inadequate to prevent fluid flow through the fluid
passage 54 disposed within the casing segmentation device 32. The
term "discrete pieces" is used herein to describe that the pieces,
created as a result of the frac-ball 52 being ruptured, are
physical portions of the frac-ball 52, as opposed to granular sized
material eroded or dissolved from the frac-ball 52 that may go into
solution within surrounding fluid.
[0042] Frac-balls 52 according to the present disclosure may be in
a spherical geometry, but are not limited to a spherical geometry.
The ball seat 60 (e.g., see FIG. 4) included in the casing
segmentation device 32 is configured to complement the frac-ball
geometry for sealing purposes. In those applications wherein a
plurality of destructible frac-balls 52 are used, some or all of
the plurality of frac-balls 52 may have the same geometry (e.g.,
same diameter spherical shape). In other applications, the
plurality of frac-balls 52 may have graduated sizes; e.g., "n"
number of spherical frac-balls 52, progressively smaller/larger in
diameter that may be used in a sliding sleeve type casing
segmentation device 32.
[0043] In some embodiments, the destructible frac-ball 52 includes
a rupture mechanism 62 (e.g., see FIGS. 8-10) that is operable to
selectively break the frac-ball 52 into the plurality of discrete
pieces described above. As indicated below, in some embodiments a
portion or all of each frac-ball piece may at least partially erode
or dissolve, but such erosion or dissolution is not the rupture
mechanism 62. An example of a rupture mechanism 62 is one that
includes an energetic material 66 (e.g., an explosive) and a
trigger mechanism 64. Another example of a rupture mechanism 62 is
a mechanical device, etc., coupled with a trigger mechanism 64. The
present disclosure therefore is not limited to any particular type
of rupture method or devices for rupturing the frac-ball 52.
[0044] The trigger mechanism 64 may assume a variety of different
forms, and the present disclosure is not limited to any particular
type of trigger mechanism 64. The trigger mechanism 64 may include
one or more processors capable of processing instructions stored in
a memory, one or more sensors (e.g., temperature sensors, pressure
sensors, magnetic, electromagnetic, conductivity, etc.), timing
devices, receivers (e.g., adapted to RF signals, ultrasonic
signals, pressure pulse signals, etc.), etc. In those embodiments
that include one or more sensors, timing devices, receivers, etc.,
such sensors, devices, or receivers may be in communication with
the processor. The trigger mechanism 64 may be implemented in a
variety of different forms (e.g., in a hardware form, or a
programmable medium, etc.). As will be explained below, different
applications may favor the use of different types of trigger
mechanisms 64, or combinations of trigger mechanism types.
[0045] A first example of a type of trigger mechanism 64 is one
that is temperature related. Some wells have well portions where
the subterranean environment is at elevated temperature. In these
applications, the fracturing fluid that is being pumped from the
surface may be no warmer than a known temperature (e.g., 80.degree.
F.) and during fracturing the aforesaid fluid will maintain a
frac-ball 52 at a temperature that is cooler than the surrounding
well environment; e.g., the fracking fluid acts as a coolant. Once
the fracturing operation at a stage is complete, the warmer
temperature reservoir fluids and gases will raise the temperature
of the frac-ball 52 via thermal conduction and/or convection. In
this instance, the trigger mechanism 64 may be an aspect that is
disabled below a predetermined temperature, and enabled at
temperatures above the predetermined temperature. For example, an
electronic component may be embedded within or attached to a
frac-ball that includes a temperature sensor. Once the temperature
sensor detects a predetermined temperature (e.g., "a trigger
temperature"), the electronic component (e.g., a processor) may
directly or indirectly initiate an energetic material adequate to
rupture the frac-ball.
[0046] In instances where the temperature within a well likely
exceeds an electronic component operating temperature (e.g., above
120.degree. C.), an alternative temperature related trigger
mechanism may be used. For example, a bimetallic device may be used
that combines a rupture mechanism and trigger mechanism. The
bimetallic device includes a first metallic alloy, a second
metallic alloy, and an energetic material. The first metallic alloy
has a first melting temperature and the second metallic alloy has a
second melting temperature, which second melting temperature is
higher than the first melting temperature. The first metallic alloy
and the second metallic alloy are exothermically reactive with one
another, and are initially separated from one another within the
device. The first metallic alloy is selected to have a melting
temperature that coincides with the desired trigger temperature for
rupturing the frac-ball. When the first metallic alloy reaches the
trigger temperature it melts, begins to flow, and contacts the
second metallic alloy, thereby triggering an exothermic reaction
between the two alloys. The exothermic reaction between the alloys
generates sufficient thermal energy to ignite the energetic
material. The ignition of the energetic material causes the
frac-ball to rupture.
[0047] A second type of trigger mechanism 64 is one that activates
upon receipt or termination of a selectively emitted signal. For
example, the trigger mechanism 64 may be selectively activated by
radio frequency energy type signal, or an acoustic energy type
signal (e.g., ultrasonic signal), a pressure pulse type signal
traveling through the fracturing fluid, etc.
[0048] Mud pulse telemetry ("MPT") is a non-limiting example of a
communication technique that can be used. In a MPT system, a
downhole located valve may be operated to restrict the flow of the
drilling fluid in a manner acceptable to transmit digital
information; e.g., opening and closing the valve to allow or
restrict, respectively, the fluid flow within the drill pipe. The
valve operation creates pressure fluctuations indicative of the
information. The pressure fluctuations propagate within the
drilling fluid towards the surface where they are received from
pressure sensors. The signals received by the pressure sensors are
subsequently processed to produce the information. As another
example, a "wired drill pipe system" may be used, wherein
electrical wires are incorporated into the casing. Electrical
signals may be conducted through the wires and received by the
frac-balls.
[0049] A third type of trigger mechanism 64 is one that actuates
based on timing; e.g., the trigger mechanism 64 can be programmed
to detonate at a particular time, or after a predetermined interval
of time (e.g., a time delay period starting from when the frac-ball
52 is deployed into the well).
[0050] A fourth type of trigger mechanism 64 is one where the
frac-ball 52 is physically processed prior to deployment. For
example, the trigger mechanism 64 can be configured to activate
upon the frac-ball 52 being spun at a predetermined rotational
speed (e.g., "X" rotations per minute--"RPMs") to arm the device
prior to deployment.
[0051] A fourth type of trigger mechanism 64 is one that may be
selectively activated via electromagnetic inductive coupling; e.g.,
selectively activated by the application or removal of a magnetic
field. For example, an electromagnetic trigger mechanism may
include an electrical insulator incorporated into the casing. To
transmit data, the device may generate an altered voltage
difference between the top part (e.g., the main casing, above the
insulator), and a second part (e.g., a drill bit, or other tools
located below the insulator). On the surface, a wire is attached to
the wellhead, which makes contact with the casing at the surface. A
second wire is attached to a rod driven into the ground some
distance away. The wellhead and the ground rod form the two
electrodes of a dipole antenna. The voltage difference between the
two electrodes is used as a signal that is received and
processed.
[0052] A fifth type of trigger mechanism 64 is one that is
activated by pressure; e.g., when the trigger mechanism 64 senses a
predetermined environmental pressure, the trigger mechanism 64 is
activated. The predetermined pressure could be the high pressure
resultant from a fracturing operation or it could simply be the
hydrostatic pressure exerted by the column of fluid in the
well.
[0053] In some embodiments, a frac-ball 52 may be configured to
include one or more safety features. For example, a frac-ball 52
may be configured to include an activating sequence that includes
an inhibit whereby prior to rupture initiation, the trigger
mechanism 64 will query its surroundings to verify certain
predetermined conditions. If the condition is satisfied, then the
trigger mechanism 64 will initiate rupture of the frac-ball 52.
Non-limiting examples of safety features include the trigger
mechanism 64 sensing to determine if the frac-ball 52 is surrounded
by ferrous material (e.g., the well pipe) or a fracturing fluid
(e.g., via conductivity). If the safety condition is not met, the
triggering mechanism will not initiate rupture of the frac-ball
52.
[0054] A non-limiting example of how a trigger mechanism 64 may be
configured is provided hereinafter. In this example, a frac-ball 52
includes a rupture mechanism 62 with a trigger mechanism 64 that
includes an electronic circuit (e.g., including the processor and
one or more of the sensors described above) powered by a battery.
The electronics are maintained in a claimant state until the
frac-ball 52 is exposed to a predetermined pressure (e.g., 500
psi). The pressure normally exerted on a frac-ball 52 at about 1100
feet below surface is about 500 psi. Fracturing operations are
almost always conducted at depths below 1100 feet, so a frac-ball
52 will always be subjected to at least 500 psi. From a safety
standpoint, there is no credible scenario on the surface where the
ball can be accidentally subjected to a predetermined pressure such
as 500 psi, hence the predetermined pressure can be used as a
safety condition. When the frac-ball 52 is subjected to the
predetermined pressure, the frac-ball electronics activate and
initiate a timer set for a predetermined time period (e.g., 10
hours). Once the predetermined time period expires, a second safety
feature may be initiated. For example, once the predetermined time
period expires, the trigger mechanism 64 may sense the surrounding
environment to determine the presence of ferrous material around
the frac-ball 52. If the safety condition is met, then the
triggering mechanism causes the frac-ball 52 to rupture. If the
trigger mechanism 64 determines the safety condition is not met,
then the electrical energy is bled from the circuit, thereby
disarming the ball and rendering it safe. As indicated above, the
above example is provided to illustrate an example of a triggering
mechanism; e.g., one that is operable to evaluate safety
conditions. The present disclosure is not limited to this
example.
[0055] In those embodiments wherein the rupture mechanism 62
includes an energetic material 66, the energetic material 66 may be
constructed from or otherwise include an amount of energetic
material 66 such as, but not limited to, lead azide, zirconium
potassium perchlorate (ZPP), gasless ignition powders such as AlA
(e.g., comprising Zirconium powder, Ferric oxide, and diatomaceous
earth), pentaerythritol tetranitrate (PETN),
cyclotrimethylenetrinitramine (RDX), and diazodinitrophenol (DDNP).
The energetic material 66 may be adapted to energize (e.g.,
activate and explode) upon receiving or otherwise being subjected
to a command signal such as, but not limited to, a radio wave
trigger. Alternatively, the energetic material 66 may also include
a detonator adapted to energize the energetic material 66 upon
receiving a command signal. In this manner, a controller or human
operator may selectively activate the energetic material 66 and
thereby selectively cause the frac-ball 52 to rupture.
[0056] Referring to FIGS. 7-10, in those embodiments wherein the
rupture mechanism 62 includes an energetic material 66, the
energetic material 66 may be included in a variety of different
configurations, and the present disclosure is not limited to any
particular configuration. For example, the energetic material 66
may be disposed internally within the frac-ball 52 (e.g., see FIG.
8), or the energetic material 66 may be configured in a form (e.g.,
a pin, a plug, etc.) that extends (e.g., radially) into the
frac-ball 52 (e.g., see FIG. 9), or the energetic material 66 may
be attached to an outer peripheral surface of the frac-ball 52
(e.g., see FIG. 10), or the energetic material 66 may be mixed with
and/or configured to form a component of the frac-ball 52, or
combinations thereof.
[0057] In some embodiments, the destructible frac-ball 52 includes
a core 50 encased (e.g., covered) within a shell 52. The present
disclosure is not limited to frac-balls 52 having a core and shell
configuration. The core 50 may be constructed from a fluid soluble
material; e.g., soluble in a fluid such as water, fracking fluid,
etc. Examples of such a core material include, but are not limited
to, salt, calcium carbonate, and polyglycolic acid. A core 50
constructed from a fluid soluble material may partially or totally
dissolve after the destructible frac-ball 52 is ruptured; e.g. once
the core material is exposed to fluids within the casing. The shell
52 may be constructed from a fluid non-soluble material; e.g.,
non-soluble in a fluid such as water, fracking fluid, etc. Examples
of a non-soluble shell material include, but are not limited to,
alumina (Al.sub.2O.sub.3), zirconia (ZrO.sub.2), and silicon
nitride (Si.sub.3N.sub.4). Alternatively, the shell 52 may be
constructed from a fluid soluble material that dissolves in the
fluid at a slower rate than the core material. Examples of such
alternative shell materials include, but are not limited to, an
aluminum alloy with micro-galvanic electrochemical cells, a
controlled electrolytic metallic, and a nano-composite material. In
those embodiments wherein the frac-ball 52 includes a core 50
disposed within a shell 52, an energetic material 66 may be
disposed within or form a part of the core 50 portion or the shell
52 portion of the frac-ball 52, or combinations thereof.
[0058] In those embodiments wherein the frac-ball 52 includes a
core 50 disposed within a shell 52, the shell 52 prevents fluids
within the casing from reaching the core 50. The shell 52 therefore
may prevent the frac-ball 52 and, more particularly, the core 50
from degrading prior to the frac-ball 52 being ruptured. However,
upon the frac-ball 52 being ruptured into a plurality of discrete
pieces, the core 50 is exposed to the surrounding fluid.
[0059] In some embodiments (e.g. see FIGS. 11 and 12), the
destructible frac-ball 52 may comprise a solid configuration; e.g.
comprised of a material that is substantially homogeneous
throughout the frac-ball 52. The term "homogeneous" is used herein
to describe a frac-ball material that is uniformly distributed
within the frac-ball 52; i.e., the frac-ball "material" may include
a plurality of materials, all of which are substantially uniformly
distributed within the frac-ball 52. A solid homogeneous material
frac-ball 52 may include a cavity 70 sized to receive at least a
portion of a rupture mechanism 62 similar to those described above,
which rupture mechanism includes a trigger mechanism 64 as
described above. FIG. 12 shows the trigger mechanism 64 attached to
the exterior surface of the frac-ball 52, and energetic material 66
disposed in the frac-ball cavity 70. In some embodiments, the
homogenous material of the solid frac-ball may be a fluid soluble
material (e.g. such as those types identified above) that may
partially or totally dissolve after the destructible frac-ball 52
is ruptured; e.g. once the core material is exposed to fluids
within the casing. The solid homogeneous material destructible
frac-ball 52 is adapted to be selectively ruptured into a plurality
of discrete pieces (e.g., as described above), with each discrete
piece smaller in volume than the frac-ball 52. At the time of
rupture, or some time thereafter, each discrete frac-ball piece is
of a size inadequate to prevent fluid flow through the fluid
passage 54 disposed within the casing segmentation device 32. To be
clear, in those instances wherein the solid homogeneous material
frac-ball 52 comprises a fluid soluble material, it is the rupture
mechanism 62 that ruptures the frac-ball into "discrete pieces" of
a size inadequate to prevent fluid flow through the fluid passage
54 disposed within the casing segmentation device 32.
[0060] In some embodiments, the destructible frac-ball 52 may
comprise a solid shell and a core comprising a non-solid material;
e.g. comprised of a liquid that may be considered to be
incompressible as used within a frac-ball. The shell is configured
such that it may be ruptured into the aforesaid "discrete pieces"
of a size inadequate to prevent fluid flow through the fluid
passage 54 disposed within the casing segmentation device 32. In
some embodiments, the destructible frac-ball 52 may include a
trigger mechanism 64 and an energetic material 66 disposed within a
fluid core frac-ball. Upon initiation, energy created by an
energetic material 66 is transmitted into the fluid core, which
would (e.g., via shock wave) cause the solid shell to break the
shell into the aforesaid discrete pieces. The core fluid would
subsequently mix with the fluid disposed within the casing.
Non-limiting examples of fluid core materials include water,
mineral oil, ballistic gelatin, and silicon oil. Fluid materials
(e.g., oils, ballistic gelatin, etc.) that have no adverse effect
on trigger mechanism electronics are particularly useful. The shell
may comprise materials as disclosed above.
[0061] In some embodiments, a casing segmentation device 32 that is
configured for use with a destructible frac-ball 52 may include one
or more rupture mechanisms 62; e.g., rupture mechanisms 62 disposed
at positions where they can act upon a seated frac-ball 52 and
cause the destructible frac-ball 52 to rupture into the aforesaid
discrete pieces. For example, a rupture mechanism 62 included with
a casing segmentation device 32 may selectively cause a mechanical
feature (e.g., a pin, blade, etc.) to strike the frac-ball 52 and
thereby cause the frac-ball 52 to rupture into the aforesaid
discrete pieces.
[0062] In some embodiments, a plurality of rupture mechanisms 62
may be used, with at least some of the rupture mechanisms 62
actuable independent of the other rupture mechanisms 62. For
example, the rupture mechanism 62 of a first frac-ball 52 may be
activated at a first frequency whereas the rupture mechanism 62 of
a second frac-ball 52 may be activated at a second frequency.
[0063] In some embodiments, the frac-balls 52 may be configured
having different sizes; e.g., diameters. In this manner, a first
frac-ball 52 may have a diameter smaller relative to the diameter
of other frac-balls 52, which smaller diameter permits the first
frac-ball 52 to pass through one or more ball seats 60 before
seating against a downstream located ball seat 60 sized to receive
and hold the first ball frac-ball 52.
[0064] While various embodiments of the present invention have been
disclosed, it will be apparent to those of ordinary skill in the
art that many more embodiments and implementations are possible
within the scope of the invention. For example, the present
invention as described herein includes several aspects and
embodiments that include particular features. Although these
features may be described individually, it is within the scope of
the present invention that some or all of these features may be
combined with any one of the aspects and remain within the scope of
the invention. Accordingly, the present invention is not to be
restricted except in light of the attached claims and their
equivalents.
* * * * *