U.S. patent application number 12/547286 was filed with the patent office on 2011-03-03 for sonically activating settable compositions.
Invention is credited to Anthony Badalamentl, Vijay Gupta, Sam Lewis, Priscilla Reyes, Brian R. Stoner.
Application Number | 20110048697 12/547286 |
Document ID | / |
Family ID | 43623113 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110048697 |
Kind Code |
A1 |
Lewis; Sam ; et al. |
March 3, 2011 |
SONICALLY ACTIVATING SETTABLE COMPOSITIONS
Abstract
The present disclosure is directed to a system and method for
sonically activating cement slurries. In some implementations, a
composition for treating a subterranean formation includes a
settable composition and an activator. The activator is released in
response to a sonic signal to initiate setting of the settable
composition.
Inventors: |
Lewis; Sam; (Duncan, OK)
; Reyes; Priscilla; (Duncan, OK) ; Gupta;
Vijay; (Morrisville, NC) ; Stoner; Brian R.;
(Chapel Hill, NC) ; Badalamentl; Anthony; (Katy,
TX) |
Family ID: |
43623113 |
Appl. No.: |
12/547286 |
Filed: |
August 25, 2009 |
Current U.S.
Class: |
166/177.4 |
Current CPC
Class: |
C04B 28/02 20130101;
C04B 28/02 20130101; C09K 8/467 20130101; C04B 40/0658 20130101;
C04B 20/1033 20130101; C04B 22/062 20130101; C04B 22/124 20130101;
C04B 12/04 20130101; C04B 22/085 20130101; C04B 24/12 20130101;
C04B 20/1033 20130101; C04B 40/0227 20130101; E21B 33/14 20130101;
C04B 20/1033 20130101; C04B 2103/46 20130101; C04B 2103/0046
20130101; C04B 22/10 20130101; C04B 40/0658 20130101 |
Class at
Publication: |
166/177.4 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A composition for treating a wellbore, comprising: a settable
composition; and an activator, wherein the activator is released in
response to a sonic signal to initiate setting of the settable
composition.
2. The composition of claim 1, wherein the settable composition
comprises at least one of a cement composition, a resin
composition, a settable mud, a conformance fluid, or a lost
circulation composition.
3. The composition of claim 1, wherein the released activator is
configured to increase a setting rate of the settable
composition.
4. The composition of claim 1, wherein the settable composition
includes a polymeric additive.
5. The composition of claim 4, wherein the polymer additive
comprises at least one of a monomer, a pre-polymer, an oligomer, or
a short chain polymer that polymerizes in response to the sonic
signal.
6. The composition of claim 1, wherein the settable composition
comprises a free-radical dopant that releases autocatalytic free
radicals in response to the sonic signal.
7. The composition of claim 6, wherein the settable composition
includes a polymeric additive, the released autocatalytic free
radicals initiate polymerization of at least a portion of the
settable composition.
8. The composition of claim 1, wherein the sonic signal decreases a
particulate size in the settable composition.
9. The composition of claim 1, wherein the sonic signal increases
at least one of pressure or temperature of the settable
composition.
10. The composition of claim 1, wherein a frequency for
transmitting the sonic signal is based, at least in part, on an
inhibitor chemistry of the settable composition.
11. The composition of claim 1, wherein the sonic signal comprises
an ultrasonic signal.
12. The composition of claim 11, wherein the ultrasonic signal
comprises transmitted at a frequency in the range of from about 20
kiloHertz (kHz) to about 2 MegaHertz (MHz).
13. The composition of claim 1, wherein the sonic signal comprises
an acoustic signal.
14. The composition of claim 13, wherein the acoustic signal is
transmitted at a frequency in the range of from about 20 Hertz to
about 20 kHz.
15. The composition of claim 1, wherein the activator is enclosed
in a shell selected from the group consisting of a polystyrene,
ethylene/vinyl acetate copolymer, polymethylmethacrylate
polyurethanes, polylactic acid, polyglycolic acid,
polyvinylalcohol, polyvinylacetate, hydrolyzed ethylene/vinyl
acetate, and copolymers thereof.
16. The composition of claim 1, wherein the activator is enclosed
in a shell that is sonically responsive polymer.
17. The composition of claim 16, wherein at least one dimension of
the shell is from about 10 nanometers to about 10,000
micrometers.
18. The composition of claim 16, wherein the shell comprises a
spheroid with at least one dimension in a range from about 5
micrometers (.mu.m) to about 20 .mu.m.
19. The composition of claim 1, wherein the activator is mixed with
the settable composition at a concentration from about 0.5% to
about 30% by weight of the settable composition.
20. The composition of claim 1, wherein the settable composition
comprises a hydraulic cement, a base fluid and a retarder.
21. The composition of claim 1, wherein the settable composition is
selected from the group consisting of Portland cement, pozzolanic
cement, high aluminate cement, gypsum cement, silica cement, high
alkalinity cement, and sorel cement.
22. The composition of claim 1, wherein the settable composition
sets in a range from about one minute to about 24 hours after
reacting with the activator.
23. The composition of claim 1, wherein the activator is selected
from a group consisting of sodium hydroxide, sodium carbonate,
amine compounds, salts comprising calcium, sodium, magnesium,
aluminum, and combinations thereof.
24. The composition of claim 1, wherein the activator is selected
from the group consisting of calcium chloride, calcium nitrite,
calcium nitrate, sodium chloride, sodium aluminate, sodium
silicate, magnesium chloride, and combinations thereof.
25. The composition of claim 1, wherein the activator is selected
from a group consisting of triethanol amine, tripropanol amine,
tri-isopropanol amine, diethanol amine, and combinations
thereof.
26. A composition for treating a wellbore, comprising: a settable
composition; and a set retarder, wherein the set retarder responds
to a sonic signal to accelerate setting of the settable
composition.
27. The composition of claim 26, wherein the sonic signal
substantially deactivates the set retarder.
28. The composition of claim 26, wherein the settable composition
sets in a range from about one minute to about 24 hours after the
set retarder responds to the sonic signal.
29. The composition of claim 26, wherein the sonic signal comprises
an ultrasonic signal.
30. The composition of claim 29, wherein the ultrasonic signal
comprises transmitted at a frequency in the range of from about 20
kiloHertz (kHz) to about 2 MHz.
31. The composition of claim 1, wherein the sonic signal comprises
an acoustic signal.
32. The composition of claim 13, wherein the acoustic signal is
transmitted at a frequency in the range of from about 20 Hertz to
about 20 kHz.
Description
TECHNICAL FIELD
[0001] This invention relates to cementing operations and, more
particularly, to sonically activating settable compositions.
BACKGROUND
[0002] Some wellbores, for example, those of some oil and gas
wells, are lined with a casing. The casing stabilizes the sides of
the wellbore. In a cementing operation, cement is introduced down
the wellbore and into an annular space between the casing and the
surrounding earth. The cement secures the casing in the wellbore,
and prevents fluids from flowing vertically in the annulus between
the casing and the surrounding earth. Different cement formulations
are designed for a variety of wellbore conditions, which may be
above ambient temperature and pressure. In designing a cement
formulation, a number of potential mixtures may be evaluated to
determine their mechanical properties under various conditions.
SUMMARY
[0003] The present disclosure is directed to a system and method
for sonically activating cement slurries. In some implementations,
a composition for treating a subterranean formation includes a
settable composition and an activator. The activator is released in
response to a sonic signal to initiate setting of the settable
composition.
[0004] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0005] FIG. 1 is an example well system for producing fluids from a
production zone;
[0006] FIGS. 2A and 2B are example cementing process in the well
system of FIG. 1;
[0007] FIGS. 3A and 3B illustrate an example activation device for
activating cement slurry in a wellbore;
[0008] FIGS. 4A and 4B illustrate example processes for releasing
activators in cement slurries;
[0009] FIG. 5 is a flow chart illustrating an example method for
activating deposited cement slurry;
[0010] FIG. 6 is a flow chart illustrating an example method for
fabricating capsules;
[0011] FIGS. 7A-F illustrate example capsules for activating a
cement slurry in the system of FIG. 1;
[0012] FIG. 8 is another example well system for producing fluids
from a production zone; and
[0013] FIGS. 9A-H illustrate example graphs demonstrating affects
of sonic signals on cement slurries.
[0014] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0015] The present disclosure is directed to one or more well
systems having an on-command cement delivery system that
selectively controls setting of a cement slurry. For example, the
described systems may use sonic irradiation (e.g., ultrasound,
terahertz), such as in the range from about 20 Hz to 2 MHz, to
release activators to initiate or accelerate the cement setting
(see FIG. 1) and/or may use ultrasound to directly activate or
accelerate cement slurries (see FIG. 8). In some instances, the
described systems may include a cement slurry and capsules that
release activators into the cement slurry in response to
ultrasound. An activator typically includes any chemicals that
activate and/or accelerate the setting process for a cement slurry
in the described systems. An activator may also retard or otherwise
affect the setting or properties of the cement slurry. For example,
the described systems may include one or more of the following
activators: sodium hydroxide, sodium carbonate, calcium chloride,
calcium nitrite, calcium nitrate, and/or others. In some
implementations, the capsules may include elements that
substantially enclose one or more activators and that release the
activator in response to at least sonic signals. For example, the
sonic signal may break or otherwise form an opening in the
encapsulating element to release the one or more activators.
[0016] In regards to directly activating cement slurries, the
described systems may directly activate the cement slurry using one
or more different mechanisms responsive to sonic signals. The one
or more different mechanisms may include modifying chemical
properties, releasing chemicals, modifying physical properties
(e.g., particle size), updating operating conditions (e.g.,
pressure, temperature), and/or other mechanisms responsive to sonic
signals. For example, described systems may use sonic signals to
directly minimize or otherwise reduce the effect of hydrophobic
surfactants to, for example, enable the surfactants to enter into
suspension and/or partially hydrate. In these instances, the
described systems may directly activate cement slurries using sonic
signals independent of introducing or adding chemicals to the
cement slurry. In addition, the systems may include free-radical
dopants in cement slurries that release autocatalytic free radicals
in response to at least ultrasonic signals. Alternatively or in
combination, the sonic signals may trigger or otherwise activate a
polymerization process in the cement slurry to provide in-situ
polymerization. In general, the described systems include a cement
slurry in an annulus formed between a casing and a wellbore, and
when the cement is set, the cement secures the casing in place. By
selectively controlling the setting of a cement slurry, the
described systems allow cement properties to be tailored once the
cement slurry has been pumped down the borehole.
[0017] Referring to FIG. 1, the system 100 is a cross-sectional
well system 100 that initiates or accelerates the setting of cement
slurring using encapsulated activators. In the illustrated
implementation, the well system 100 includes a production zone 102,
a non-production zone 104, a wellbore 106, a cement slurry 108, and
capsules 110. The production zone 102 may be a subterranean
formation including resources (e.g., oil, gas, water). The
non-production zone 104 may be one or more formations that are
isolated from the wellbore 106 using the cement slurry 108. For
example, the zone 104 may include contaminants that, if mixed with
the resources, may result in requiring additional processing of the
resources and/or make production economically unviable. The cement
slurry 108 may be pumped or selectively positioned in the wellbore
106, and the setting of the cement slurry 108 may be activated or
accelerated using the capsules 110. In some implementations, the
capsules 110 may release activators in response to ultrasound
initiated by, for example, a user of the system 100. By controlling
the setting, a user may configure the system 100 without
substantial interference from the setting of the cement slurry
108.
[0018] Turning to a more detailed description of the elements of
system 100, the wellbore 106 extends from a surface 112 to the
production zone 102. The wellbore 106 may include a rig 114 that is
disposed proximate to the surface 112. The rig 114 may be coupled
to a casing 116 that extends the entire length of the wellbore or a
substantial portion of the length of the wellbore 106 from about
the surface 112 towards the production zones 102 (e.g.,
hydrocarbon-containing reservoir). In some implementations, the
casing 116 can extend past the production zone 102. The casing 116
may extend to proximate a terminus 118 of the wellbore 106. In some
implementations, the well 106 may be completed with the casing 116
extending to a predetermined depth proximate to the production zone
102. In short, the wellbore 106 initially extends in a
substantially vertical direction toward the production zone 102. In
some implementations, the wellbore 106 may include other portions
that are horizontal, slanted or otherwise deviated from
vertical.
[0019] The rig 114 may be centered over a subterranean oil or gas
formation 102 located below the earth's surface 112. The rig 114
includes a work deck 124 that supports a derrick 126. The derrick
126 supports a hoisting apparatus 128 for raising and lowering pipe
strings such as casing 116. Pump 130 is capable of pumping a
variety of wellbore compositions (e.g., drilling fluid, cement)
into the well and includes a pressure measurement device that
provides a pressure reading at the pump discharge. The wellbore 106
has been drilled through the various earth strata, including
formation 102. Upon completion of wellbore drilling, the casing 116
is often placed in the wellbore 106 to facilitate the production of
oil and gas from the formation 102. The casing 116 is a string of
pipes that extends down wellbore 106, through which oil and gas
will eventually be extracted. A cement or casing shoe 132 is
typically attached to the end of the casing string when the casing
string is run into the wellbore. The casing shoe 132 guides the
casing 116 toward the center of the hole and may minimize or
otherwise decrease problems associated with hitting rock ledges or
washouts in the wellbore 106 as the casing string is lowered into
the well. The casing shoe 132 may be a guide shoe or a float shoe,
and typically comprises a tapered, often bullet-nosed piece of
equipment found on the bottom of the casing string 116. The casing
shoe 132 may be a float shoe fitted with an open bottom and a valve
that serves to prevent reverse flow, or U-tubing, of cement slurry
108 from annulus 122 into casing 116 after the cement slurry 108
has been placed into the annulus 122. The region between casing 116
and the wall of wellbore 106 is known as the casing annulus 122. To
fill up casing annulus 122 and secure casing 116 in place, casing
116 is usually "cemented" in wellbore 106, which is referred to as
"primary cementing." In some implementations, the cement slurry 108
may be injected into the wellbore 106 through one or more ports 134
in the casing shoe 132. The cement slurry 108 may flow through a
hose 136 into the casing 116. In some instances where the casing
116 does not extend the entire length of the wellbore 106 to the
surface 112, the casing 116 may be supported by a liner hanger 138
near the bottom of a previous casing 120.
[0020] In some implementations, the system 100 may activate the
setting of the cement slurry 108 using the capsules 110 during, for
example, conventional primary cementing operation. In conventional
primary cementing implementations, the capsules 110 may be mixed
into the cement slurry 108 prior to entering the casing 116, and
the cement slurry 108 may then be pumped down the inside of the
casing 116. For example, the capsules 110 may be mixed in the
cement slurry 108 at a density in the range of 4-24 pound per
gallon (ppg). As the slurry 108 reaches the bottom of casing 116,
it flows out of casing 116 and into casing annulus 122 between
casing 116 and the wall of wellbore 106. As cement slurry flows up
annulus 122, it displaces any fluid in the wellbore. To ensure no
cement remains inside casing 116, devices called "wiper plugs" may
be pumped by a wellbore servicing fluid (e.g., drilling mud)
through casing 116 behind the cement slurry 108. The wiper contacts
the inside surface of casing 116 and pushes any remaining slurry
108 out of casing 116. When cement slurry reaches the earth's
surface 112, and annulus 122 is filled with slurry 108, pumping is
terminated. In connection with pumping the cement slurry 108 into
the annulus, an ultrasonic signal may be transmitted before,
during, and/or after the pumping is complete to activate the
capsules 110. In response to at least the signal, the capsules 110
may release activators that initiate and/or accelerate the setting
of the cement slurry 108 in the annulus 122. Some or all of the
casing 116 may be affixed to the adjacent ground material with set
cement 202 as illustrated in FIGS. 2A and 2B. In some
implementations, the casing 116 comprises a metal. After setting,
the casing 116 may be configured to carry a fluid, such as air,
water, natural gas, or to carry an electrical line, tubular string,
or other elements.
[0021] After positioning the casing 116, a settable slurry 108
including capsules 110 may be pumped into annulus 122 by a pump
truck (not illustrated). While the following discussion will center
on the settable slurry 108 comprising a cement slurry 108, the
settable slurry 108 may include other compounds such as resin
systems, settable muds, conformance fluids, lost circulation,
and/or other settable compositions. Example cement slurries 108 are
discussed in more detail below. In connecting with depositing or
otherwise positioning the cement slurry 108 in the annulus 122, the
capsules 110 may release activators to activate or otherwise
increase the setting rate of the cement slurry 108 in response to
at least ultrasound. In other words, the released activators may
activate the cement slurry 108 to set cement in the annulus
122.
[0022] In some implementations, the capsules 110 may release an
activator that initiates or accelerates the setting of the cement
slurry 108. For example, the cement slurry 108 may remain in a
substantially slurry state for a specified period of time, and the
capsules 110 may activate the cement slurry in response to
ultrasound. In some instances, ultrasound may crack, break or
otherwise form one or more holes in the capsules 110 to release the
activators. In some instances, the ultrasound may generate heat
that melts one or more holes in the capsules 110. The capsules 110
enclose the activators with, for example, a membrane such as a
polymer (e.g., polystyrene, ethylene/vinyl acetate copolymer,
polymethylmethacrylate, polyurethanes, polylactic acid,
polyglycolic acid, polyvinylalcohol, polyvinylacetate, hydrolyzed
ethylene/vinyl acetate, or copolymers thereof). The capsule 110 may
include other materials responsive to ultrasound. In these
implementations, the capsule 110 may include a polymer membrane
that ultrasonically degrades to release the enclosed activators. In
some examples, an ultrasonic signal may structurally change the
membrane to release the activators such as, for example, opening a
preformed slit in the capsules 110. In some implementations, at
least one dimension of the capsules 110 may be microscopic such as
in range from 10 nanometers (nm) to 15,000 nm. For example, the
dimensions of the capsules 110 may be on a scale of a few tens to
about one thousand nanometers and may have one or more external
shapes including spherical, cubic, oval and/or rod shapes. In some
implementations, the capsules 110 can be shells with diameters in
the range from about 10 nm to about 1,000 nm. In other
implementations, the capsules 110 can include a diameter in a range
from about 15 micrometers to about 10,000 micrometers.
Alternatively or in combination, the capsules 110 may be made of
metal (e.g., gold) and/or of non-metallic material (e.g., carbon).
In some implementations, the capsules 110 may be coated with
materials to enhance their tendency to disperse in the cement
slurry 108. The capsules 110 may be dispersed in the cement slurry
at a concentration of 10.sup.5 to 10.sup.9 capsules/cm.sup.3. In
some implementations, the capsules 110 are a shell selected from
the group consisting of a polystyrene, ethylene/vinyl acetate
copolymer, and polymethylmethacrylate, polyurethanes, polylactic
acid, polyglycolic acid, polyvinylalcohol, polyvinylacetate,
hydrolyzed ethylene/vinyl acetate, and copolymers thereof.
[0023] The release activator may include sodium hydroxide, sodium
carbonate, amine compounds, salts comprising calcium, sodium,
magnesium, aluminum, and/or a mixture thereof. The capsule 110 may
release a calcium salt such as calcium chloride. In some
implementations, the capsule 110 may release a sodium salt such as
sodium chloride, sodium aluminate, and/or sodium silicate. The
capsule 110 may release a magnesium salt such as magnesium
chloride. In some examples, the capsule 110 may release amine
compounds such as triethanol amine, tripropanol amine,
tri-isopropanol amine, and/or diethanol amine. In some
implementations, the capsule 110 may release the activator in a
sufficient amount to set the cement slurry 108 within about 1
minute to about 24 hours. In implementations including sodium
chloride as the released activator, the concentration may be in the
range of from about 3% to about 30% by weight of the cement in the
cement slurry 108. In implementations including calcium chloride as
the released activator, the concentration may be in the range of
from about 0.5% to about 5% by weight of the cement in the cement
slurry 108. In the case that the settable slurry 108 comprises
resin, the release activator may include amine accelerators for a
epoxy/novalac resins.
[0024] In some implementations, the capsule 110 may "flash-set" the
cement slurry 108. As referred to herein, the term "flash-set" will
be understood to mean the initiation of setting of the cement
slurry 108 within about 1 minute to about 15 minutes after
contacting the released activator. In some implementations, the
previously identified activators may flash set the cement slurry
108. Flash-set activators may include sodium hydroxide, sodium
carbonate, potassium carbonate, bicarbonate salts of sodium or
potassium, sodium silicate salts, sodium aluminate salts, ferrous
and ferric salts (e.g., ferric chloride and ferric sulfate),
polyacrylic acid salts, and/or others. In some implementations, the
following activators can flash-set the cement slurry 108 based on
these activators exceeding a specified concentration: calcium
nitrate, calcium acetate, calcium chloride, and/or calcium nitrite.
In some implementations, the capsule 110 may release a solid
activator.
[0025] In some implementations, the cement slurry 108 may comprise
a "delayed set" cement compositions that remain in a slurry state
(e.g., resistant to setting or gelation) for an extended period of
time. In such implementations, a delay-set cement slurry 108 may
include a cement, a base fluid, and a set retarder. In these and
other implementations, activation may change the state of the
cement slurry from delay set to neutral, to accelerated, or to less
delayed. The cement slurry 108 may include other additives. The
delayed-set cement slurry 108 typically remains in a slurry state
for in range of about 6 hours to about 4 days under downhole or
other conditions. That said, the cement slurry 108 may include
components that result in a slurry state for a greater, or shorter,
amount of time. For example, the cement slurry 108 may be mixed or
otherwise made well ahead of positioning the slurry 108 in the
annulus 122. The delayed-set cement slurry 108 can, in some
implementations, include a cement, a base fluid, and a set
retarder. The delayed-set cement slurry 108 may be set at a desired
time, such as after placement, by activating the capsules 110 to
release one or more activators.
[0026] In regards to cements included in the cement slurry 108, any
cement suitable for use in subterranean applications may be
suitable for use in the present invention. For example, delayed-set
cement slurry 108 may include a hydraulic cement. In general,
hydraulic cements typically include calcium, aluminum, silicon,
oxygen, and/or sulfur and may set and harden by reaction with
water. Hydraulic cements include, but are not limited to, Portland
cements, pozzolanic cements, high aluminate cements, gypsum
cements, silica cements, high alkalinity cements, and/or Sorel
cements. In addition, the delayed-set cement slurry 108 may include
cements based on shale or blast furnace slag. In these instances,
the shale may include vitrified shale, raw shale (e.g., unfired
shale), and/or a mixture of raw shale and vitrified shale. In some
implementations, the settable composition 108 includes a polymer
additive comprising at least one of a monomer, a pre-polymer, an
oligomer, or a short chain polymer that polymerizes in response to
the sonic signal
[0027] In regards to base fluids included in the cement slurry 108,
the delayed-set cement slurry 108 may include one or more base
fluids such as, for example, an aqueous-based base fluid, a
nonaqueous-based base fluid, or mixtures thereof. Aqueous-based may
include water from any source that does not contain an excess of
compounds (e.g., dissolved organics, such as tannins) that may
adversely affect other compounds in the cement slurry 108. For
example, the delayed-set cement slurry 108 may include fresh water,
salt water (e.g., water containing one or more salts), brine (e.g.,
saturated salt water), and/or seawater. Nonaqueous-based may
include one or more organic liquids such as, for example, mineral
oils, synthetic oils, esters, and/or others. Generally, any organic
liquid in which a water solution of salts can be emulsified may be
suitable for use as a base fluid in the delayed-set cement slurry
108. In some implementations, the base fluid exceeds a
concentration sufficient to form a pumpable slurry. For example,
the base fluid may be water in an amount in the range of from about
25% to about 150% by weight of cement ("bwoc") such as one or more
of the following ranges: about 30% to about 75% bwoc; about 35% to
about 50% bwoc; about 38% to about 46% bwoc; and/or others.
[0028] In regards to set retarders in the cement slurry 108, the
cement slurry 108 may include one or more different types of set
retarders such as, for example, phosphonic acid, phosphonic acid
derivatives, lignosulfonates, salts, organic acids,
carboxymethylated hydroxyethylated celluloses, synthetic co- or
ter-polymers comprising sulfonate and carboxylic acid groups,
and/or borate compounds. And In some implementations, the set
retarders used in the present invention are phosphonic acid
derivatives. Examples of set retarders may include phosphonic acid
derivatives commercially available from, for example, Solutia
Corporation of St. Louis, Mo. under the trade name "DEQUEST."
Another example set retarder may include a phosphonic acid
derivative commercially available from Halliburton Energy Services,
Inc., under the trade name "MICRO MATRIX CEMENT RETARDER." Example
borate compounds may include sodium tetraborate, potassium
pentaborate, and/or others. A commercially available example of a
suitable set retarder comprising potassium pentaborate is available
from Halliburton Energy Services, Inc. under the trade name
"Component R." Example organic acids may include gluconic acid,
tartaric acid, and/or others. An example of a suitable organic acid
may be commercially available from Halliburton Energy Services,
Inc. under the trade name "HR.RTM. 25." Other examples of set
retarders may be commercially available from Halliburton Energy
Services, Inc. under the trade names "SCR-100" and "SCR-500."
Generally, the set retarder in the delayed-set cement slurry 108
may be in an amount sufficient to delay the setting in a
subterranean formation for a specified time. The amount of the set
retarder included in the cement slurry 108 may be in one or more of
the following ranges: about 0.1% to about 10% bwoc; about 0.5% to
about 4% bwoc; and/or others.
[0029] In some implementations, the cement slurry 108 may not
include a set retarder. For example, the system slurry 108 may
include high aluminate cements and/or phosphate cements independent
of a set retarder. In these instances, the activators may initiate
setting of the slurry 108. For example, these activators may
include alkali metal phosphate salts. High aluminate cement may
comprise calcium aluminate in an amount in the range of from about
15% to about 45% by weight of the high aluminate cement, Class F
fly ash in an amount in the range of from about 25% to about 45% by
weight of the high aluminate cement, and sodium polyphosphate in an
amount in the range of from about 5% to about 15% by weight of the
high aluminate cement. In certain embodiments of the present
invention wherein a cement composition comprising a phosphate
cement is used, a reactive component of the cement composition
(e.g., the alkali metal phosphate salt) may be used as an
activator.
[0030] FIGS. 2A and 2B illustrate a cross sectional view of the
well system 100 including activated set cement 202 in at least a
portion of the annulus 122. In particular, the capsules 110
released activators in at least a portion of the cement slurry 108
to form the set cement 202. In FIG. 2A, the cement slurry flowed
into the annulus 122 through the casing 116, and in response to at
least a signal, the capsules 110 in the slurry 108 released an
activator. In the illustrated example, substantially all capsules
110 in the annulus 122 released activators to form the set cement
202 along substantially the entire length of the annulus 122.
Referring to FIG. 2B, the cement slurry 108 flowed into the annulus
122 through the casing 116, and in response to at least an
ultrasonic signal, the capsules 110 in the slurry 108 released
activators within a specified location 204. In the illustrated
example, the region or location 204 is located proximate the zone
102. In other words, the capsules 110 proximate the zone 102 may
release activators and form the set cement 202 located in the
region 204. The ultrasonic signal may be localized to the region
identified by 204, and in response to at least the localized
signal, the set cement 204 forms. In some implementations, an
initial amount of the cement slurry 108 may be exposed to an
ultrasonic signal such that the setting period may be substantially
equal to a period of time for the setting cement slurry 108 to flow
to the location 204. In these examples, the cement slurry 108 may
be exposed to the ultrasonic signal as the slurry 108 including the
capsules 110 enters the casing 116. As the leading edge of cement
slurry 108 begins to set, fluid flow through the annulus 122 may
become more restricted and may eventually cease. Thus, the cement
slurry 108 may be substantially prevented from flowing onto the
surface 112 through the annulus 122. The remainder of the cement
slurry 108 may set in the annulus 122 behind the leading edge as
illustrated in FIG. 2A or the cement slurry 108 may set at a later
time as illustrated in FIG. 2B. In the later, the remaining cement
slurry 108 may be exposed to ultrasonic signals at a later time to
initiate or accelerate the setting processes.
[0031] FIGS. 3A and 3B illustrates an example capsule 110 of FIG. 1
in accordance with some implementations of the present disclosure.
In this implementation, the capsule 110 is spherical but may be
other shapes as discussed above. The capsule 110 is a shell 302
encapsulating one or more activators 304 as illustrated in FIG. 3B.
The capsule 110 releases one or more stored activators 304 in
response to at least an ultrasonic signal. For example, the capsule
110 may crack or otherwise form one or more holes in response to at
least the ultrasonic signal. The illustrated capsule 110 is for
example purposes only, and the capsule 110 may include some, none,
or all of the illustrated elements without departing from the scope
of this disclosure.
[0032] FIGS. 4A and 4B illustrate example implementations of the
capsules 110 releasing one or more activators. The capsules 110 may
release activators by heating one or more portions to form at least
one opening, destroying or otherwise removing one or more portions,
and/or other processes. The following implementations are for
illustration purposes only, and the capsules 110 may release
activators using some, all or none of these processes.
[0033] Referring to FIG. 4A, the capsule 110 forms an opening
through heat formed from ultrasonic signals. For example, the
ultrasonic signals may directly heat the membrane of the capsule
110 and/or heat the surrounding cement slurry 108 to a temperature
above the melting point. The capsule 110 may be a gold shell that
when vibrated at its natural frequency melts at least a portion of
the shell to release the enclosed activators. In these instances,
the generated heat may melt or otherwise deform the shell to form
an opening. In addition to metal membranes, the capsule 110 may be
other materials such as a polymer. Referring to FIG. 4B, the
capsule 110 forms cracks, breaks, or openings in response
ultrasonic signals. For example, the ultrasonic signal may crack or
otherwise destroy portions of the capsule 110. In some
implementations, the ultrasound may form defects in the membrane of
the capsule and, as a result, form one or more openings as
illustrated.
[0034] FIGS. 5 and 6 are flow diagrams illustrating example methods
500 and 600 for implementing and manufacturing devices including
one or more activators. The illustrated methods are described with
respect to well system 100 of FIG. 1, but these methods could be
used by any other system. Moreover, well system 100 may use any
other techniques for performing these tasks. Thus, many of the
steps in these flowcharts may take place simultaneously and/or in
different order than as shown. The well system 100 may also use
methods with additional steps, fewer steps, and/or different steps,
so long as the methods remain appropriate.
[0035] Referring to FIG. 5, method 500 begins at step 502 where
capsules are selected based, at least in part, on one or more
parameters. For example, the capsules 110 and the enclosed
activators may be based, at least in part, on components of the
cement slurry 108. In some implementations, the capsules 110 may be
selected based on downhole conditions (e.g., temperature). At step
504, the selected capsules are mixed with a cement slurry. In some
examples, the capsules 110 may be mixed with the cement slurry 108
as the truck 130 pumps the slurry into the annulus 122. In some
examples, the capsules 110 may be mixed with dry cement prior to
generating the cement slurry 108. Next, at step 506, the cement
slurry including the capsules are pumped downhole. In some
instances, the cement slurry 108 including the capsules 110 may be
pumped into the annulus 122 at a specified rate. One or more
ultrasonic signals are transmitted to the at least a portion of the
downhole cement slurry at step 508. Again in the example, the
transmitter may be lowered into the casing to transmit signals at a
portion of the cement slurry 108. In this example, the transmitted
signals may activate the capsules 110 proximate the shoe 132 to set
that portion of the cement slurry 108 as illustrated in FIG. 2B. In
some instances, the casing 116 may be moved (e.g., up/down) to
assist in distributing the activators as desired.
[0036] Referring to FIG. 6, the method 600 begins at step 602 where
a first emulsification step is performed. For example, a
polystyrene dissolved in CH.sub.2Cl.sub.2 where saturated aqueous
CaCl.sub.2 may be emulsified using WS-36 (Sorbitan Monooleate).
Next, at step 604, the first emulsification may then again be
emulsified in a second step. In the example, the first emulsion may
then be subsequently emulsified into a large volume (e.g.,
10.times. excess) of a 2% polyvinylalcohol solution.
[0037] FIGS. 7A-F illustrate an example implementation of the
capsules 110 in accordance with some implementations of the present
disclosure. In this example, implementation, the capsules 110
encapsulate activators, and power ultrasound may break the capsules
to release the activators on command. The illustrated capsules 110
are polystyrene microcapsules encapsulating aqueous CaCl.sub.2.
Though, the capsules 110 may be formed from other materials such as
ethylene/vinyl acetate copolymer, polymethylmethacrylate, and/or
others. In some instances, these types of capsules 110 may be
created using a double emulsion technique. For example, the
technique may include a polystyrene dissolved in CH.sub.2Cl.sub.2
where saturated aqueous CaCl.sub.2 was emulsified using WS-36
(Sorbitan Monooleate). Next, this emulsion may then be subsequently
emulsified into a large volume (e.g., 10.times. excess) of a 2%
polyvinylalcohol solution. The double emulsion was stirred and
heated to about 30.degree. C. to drive off CH.sub.2Cl.sub.2 and
concentrate the polystyrene ultimately forming liquid filled
microcapsules. To evaluate these capsules, four different cement
slurries were tested and the results are graphed in FIGS. 7C-F. A
retarded slurry, a retarded slurry with CaCl.sub.2, a retarded
slurry with the microcapsules, and a retarded slurry with the
microcapsules treated with sonication were evaluated. A 20 kHz
ultrasonic horn was used for ten minutes at 50% power to treat the
sonicated sample. The composition and results are listed in Tables
1-3 below.
TABLE-US-00001 TABLE 1 Slurry 1 Slurry 2 Slurry 3 Slurry 4 Base
Retarded w/ Encapsulated Sonicated Description Retarded CaCl.sub.2
CaCl.sub.2 Encap CaCl.sub.2 Water 39.4% bwc 39.4% bwc 39.4% bwc
39.4% bwc 332 g 332 g 332 g 332 g Class H 100% bwc 100% bwc 100%
bwc 100% bwc 842.5 g 842.5 g 842.5 g 842.5 g HR-800 0.25% bwc 0.25%
bwc 0.25% bwc 0.25% bwc 2.1 g 2.1 g 2.1 g 2.1 g CaCl.sub.2 0.27%
bwc 2.3 g Encapsulated 0.27% bwc 0.27% bwc CaCl.sub.2 2.3 g 2.3
g
TABLE-US-00002 TABLE 2 Density- 16.4 ppg Yield- 1.07
ft.sup.3/sk
TABLE-US-00003 TABLE 3 Slurry 1 Slurry 2 Slurry 3 Slurry 4 Pump
time 14:19 9:17 12:20 7:35 (70BC) Hydration Heat 16:00 11:00 16:00
11:20
[0038] The illustrated parameters including operating conditions
are for illustration purposes only. The system 100 may use some,
all or none of the values without departing from the scope of this
disclosure.
[0039] FIG. 8 is another example system 100 that directly activates
the cement slurry 108 using ultrasonic signals. For example,
ultrasonic transducers 802a and 802b may be affixed to the exterior
of the casing 116 and emit ultrasound to sonically activate the
cement slurry. By sonically activating the cement slurry, the
system 100 may set cement on-demand. For example, the system 100
may set the cement slurry 108 in a period of the range from 1 hour
to 1 day. The sonic transducers 802 may directly activate the
cement slurry 108 using one or more different mechanisms responsive
to sonic signals. The one or more different mechanisms may include
modifying chemical properties, releasing chemicals, modifying
physical properties (e.g., particle size), updating operating
conditions (e.g., pressure, temperature), and/or other mechanisms
responsive to sonic signals. For example, the sonic transducers 802
may reduce the particulate size in the cement slurry 108 and, as a
result, may increase the surface area. By increasing the surface
area, the setting process may be initiated, accelerated, or
otherwise activated. Alternatively or in combination, the sonic
signals may increase the pressure and/or temperature and, as a
result, may initiate, accelerate, or otherwise activate the setting
process. In some implementations, the ultrasonic transducers 802
may activate accelerators in the cement slurry 108 and/or
deactivate cement retarders in the cement slurry 108 to set the
cement on demand. For example, the ultrasonic transducers 802 may
generate ultrasonic or acoustic waves to initiate the setting
process of the cement slurry 108 through, for example, the
selective activation of accelerators in the cement slurry 108 such
as CaCl.sub.2 and/or the deactivation of cement retarders in the
cement slurry 108 such as xylose. In some implementations, cement
hydration inhibitors (in relatively low concentration) can work to
alter the surface energy of the tricalcium aluminate, silicate
and/or other compounds in the cement slurry 108, which can make the
compounds more hydrophobic. The transducers 802 may ultrasonically
agitate the cement slurry 108 to reduce the effect of hydrophobic
surfactants, which may enable the compounds to enter into solution
and/or partially hydrate. The transducers 802 may generate
ultrasonic signals having a frequency that substantially matches
the resonant conditions for inhibitor neutralization. In some
implementations, the system 100 may execute frequency tuning to
substantially optimize frequency and power combinations for a given
geometry and inhibitor chemistry. In these instances, a user of the
system 100 may remotely control the initiation of cement hydration.
In addition, the system 100 may initiate an autocatalytic process.
For example, the transducers 802 may generate ultrasonic signals
that sets off an autocatalytic free-radical release that propagates
through the cement slurry 108. In these instances, this process may
initiate from a single point. The cement slurry 108 may include
additives (e.g., free-radical dopants) that release free-radical
species through out the slurry 108 in response to at least
ultrasonic initiation or hydration.
[0040] FIGS. 9A-H illustrate example graphs demonstrating affects
of sonic signals on cement slurries. In these examples,
measurements were made on cement slurries that were sonically
activated in comparison to cement slurries not sonically activated.
In particular, ultrasound was used to accelerated the set of
retarded cement slurries. The cement slurries were retarded using
one of the following three retarders: EDTA; a combination of
FDP-C742A and EDTA; and a combination of FDP-C742A and Component R.
Without exposure to ultrasound, the cement slurries pumped between
6.5 hours to 80 hours. After exposure to 20 kHz of ultrasound, the
pump times for these slurries may be reduced 40-50%. In addition, a
control pump time using neat cement with and without exposure to
ultrasound was run. The ultrasound exposure did not appear to
affect the pump time of the neat cement. Based, at least in part,
on the data, the ultrasound appears to target the retarders and may
be accelerating the setting process as a result.
[0041] Referring to FIG. 9A, the graph 910 plots data for cement
slurry comprising 16.4 PPG (Class H cement, neat) operating at
120.degree. F. and 3600 PSI in 30 minutes. The cement slurry was
not exposed to ultrasound. The graph 910 includes a peak 912
indicating the pump time to be 2 hours and 23 minutes. Referring to
FIG. 9B, the graph 920 plots data for the same cement slurry as
graph 910 including exposure to 20 kHz ultrasound for seven
minutes. In this experiment, the ultrasound was shut off after 5
minutes to due to an increase in the cement-slurry temperature. The
cement slurry was exposed to an additional 2 minutes of the
ultrasound once cooled. The graph 920 includes a peak 922
indicating the pump time to be 2 hours.
[0042] Referring to FIG. 9C, the graph 930 plots data for cement
slurry comprising 16.4 PPG (Class H cement, 1% EDTA) operating at
120.degree. F. and 3600 PSI in 30 minutes. The cement slurry was
not exposed to ultrasound. The graph 930 includes a peak 932
indicating the pump time to be 7 hours and 45 minutes. Referring to
FIG. 9D, the graph 940 plots data for the same cement slurry as
graph 930 including exposure to 20 kHz ultrasound for 7 minutes (5
minutes on, 2 minutes off, 2 minutes on). In this experiment, the
ultrasound was shut off after 5 minutes due to an increase in the
cement-slurry temperature. The cement slurry was exposed to an
additional 2 minutes of the ultrasound once cooled. The pump time
was 4 hours 15 minutes.
[0043] Referring to FIG. 9E, the graph 950 plots data for cement
slurry comprising 16.4 PPG (Class G cement w/35% SSA-1; 10.4 SSA-1;
1% CFR-3; 0.8% Halad-200; 0.4 gal/sk Gascon 469; 1.8% FDP-C742A;
1.8% EDTA; 0.3 gal/sk NF-6) with the % in bwoc. The operating
conditions were 400.degree. F. and 13100 PSI in 90 minutes. The
cement slurry was not exposed to ultrasound. The pump time was 6
hours and 46 minutes. Referring to FIG. 9F, the graph 960 plots
data for the same cement slurry as graph 950 including exposure to
20 kHz ultrasound for 15 minutes (10 minutes on, 1 minutes off, 5
minutes on). In this experiment, the ultrasound was shut off after
10 minutes due to an increase in the cement-slurry temperature. The
cement slurry was exposed to an additional 5 minutes of the
ultrasound once cooled. The pump time was 3 hours 15 minutes.
[0044] Referring to FIG. 9G, the graph 970 plots data for cement
slurry comprising 16.4 PPG (Class G cement w/35% SSA-1; 10.4 SSA-1;
1% CFR-3; 0.8% Halad-200; 0.4 gal/sk Gascon 469; 1.8% FDP-C742A;
0.8% Compound R; 0.3 gal/sk NF-6) with the % in bwoc. The operating
conditions were 422.degree. F. and 13100 PSI in 90 minutes. The
cement slurry was not exposed to ultrasound. The pump time was 79
hours. Referring to FIG. 9H, the graph 980 plots data for the same
cement slurry as graph 970 including exposure to 20 kHz ultrasound
for 15 minutes (5 minutes intervals). The pump time was 50
hours.
[0045] The present invention is well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein.
The particular embodiments disclosed above are illustrative only,
as the present invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular illustrative embodiments disclosed
above may be altered or modified and all such variations are
considered within the scope and spirit of the present invention.
While compositions and methods are described in terms of
"comprising," "containing," or "including" various components or
steps, the compositions and methods can also "consist essentially
of" or "consist of" the various components and steps. Whenever a
numerical range with a lower limit and an upper limit is disclosed,
any number and any included range falling within the range is
specifically disclosed. In particular, every range of values (of
the form, "about a to about b," or, equivalently, "from
approximately a to b," or, equivalently, "from approximately a-b")
disclosed herein is to be understood to set forth every number and
range encompassed within the broader range of values. Also, the
terms in the claims have their plain, ordinary meaning unless
otherwise explicitly and clearly defined by the patentee.
* * * * *