Note: Descriptions are shown in the official language in which they were submitted.
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
HIGH EFFICIENCY RADIATION-INDUCED TRIGGERING FOR SET-ON-
COMMAND COMPOSITIONS AND METHODS OF USE
BACKGROUND
[0001] The embodiments described herein relate to systems and
methods that utilize bremsstrahlung radiation to facilitate the setting of a
settable composition.
[0002] Natural resources such as oil and gas located in a subterranean
formation can be recovered by drilling a wellbore down to the subterranean
formation, typically while circulating a drilling fluid in the wellbore. After
the
wellbore is drilled, a string of pipe (e.g., casing) can be run in the
wellbore. The
drilling fluid is then usually circulated downwardly through the interior of
the
pipe and upwardly through the annulus between the exterior of the pipe and the
walls of the wellbore, although other methodologies are known in the art.
[0003] Hydraulic cement compositions are commonly employed in the
drilling, completion and repair of oil and gas wells. For example, hydraulic
cement compositions are utilized in primary cementing operations whereby
strings of pipe such as casing or liners are cemented into wellbores. In
performing primary cementing, a hydraulic cement composition is pumped into
the annular space between the walls of a wellbore and the exterior surfaces of
a
pipe string disposed therein to harden. After the cement is placed within the
wellbore, a period of time is needed for the cement to cure and obtain enough
mechanical strength for drilling operations to resume. This down time is often
referred to as "wait-on-cement", or WOC. The WOC time ranges from a few
hours to several days, depending on the difficulty and criticality of the
cement
job in question. It is desirable to reduce the WOC time, so that the crew can
recommence the drilling operation, and thus reduce the total time and cost of
operations. If operations are resumed prior to the cement obtaining sufficient
mechanical strength, the structural integrity of the cement can be
compromised.
As such, systems generally are over-engineered to have very long setting (or
thickening) times in order to ensure that the mix remains fluid until all of
the
cementitious material is in place, which can result in excessive WOC.
BRIEF DESCRIPTION OF THE DRAWINGS
1
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
[0004] The following figures are included to illustrate certain aspects of
the embodiments described herein, and should not be viewed as exclusive
embodiments. The subject matter disclosed is capable of considerable
modifications, alterations, combinations, and equivalents in form and
function,
as will occur to those skilled in the art and having the benefit of this
disclosure.
[0005] FIG. 1 illustrates a cross sectional side view of a wellbore.
[0006] FIG. 2 provides a cross-sectional illustration of a system for
producing bremsstrahlung photons downhole in accordance with at least some
embodiments described herein.
[0007] FIG. 3 provides a cross-sectional illustration of a system for
producing bremsstrahlung photons downhole in accordance with at least some
embodiments described herein.
DETAILED DESCRIPTION
[0008] The embodiments described herein relate to systems and
methods that utilize bremsstrahlung radiation to facilitate the setting of a
settable composition.
[0009] The systems and methods described herein use bremsstrahlung
photons to set settable compositions (e.g., resins, cements, settable muds,
lost
circulation fluids, conformance fluids, and combinations thereof). As used
herein,
the term "set" refers to an increase in mechanical strength of a settable
composition (e.g., in a fluid or slurry form) sufficient to perform a desired
result,
such as to restrict movement of an item or impede fluid flow or pressure
transfer
through a fluid. In some instances, a cement may be referred to as set when it
can restrict the movement of a pipe, or impede fluid flow or pressure
transfer,
regardless of whether the cement has cured to a fully solid composition. In
some
instances, a fluid or slurry can be referred to as set when it has thickened
to a
sufficient level that it achieves the desired result, such as the isolation of
a
particular zone or the restriction of fluid flow or pressure transfer,
regardless of
whether it has reached its final consistency.
[0010] The use of bremsstrahlung photons may be advantageous in
wellbore environments because the production of bremsstrahlung photons can
be made more efficient than the production of other ionizing particles like
neutrons and protons can be made. Therefore, the amount of energy per particle
required to produce bremsstrahlung photons of suitable penetration capability
is
2
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
less, which minimizes the power requirements and heat dissipation. Further,
because bremsstrahlung photons are produced from the deceleration of
electrons, a precursor fuel, like deuterium or tritium, is not needed.
Additionally,
high intensities of the bremsstrahlung photons (1014 photons per second) can
be
readily achieved as compared to other ionizing radiations. For example, it is
very
difficult to produce even 1012 deuterium-tritium neutrons per second without
producing challenging heat loads.
[0011] In some embodiments, a settable composition may include set
accelerators and set retarders that may be released, activated, or deactivated
on-command by irradiation with bremsstrahlung photons. When used in
cementing operations in subterranean formations, the settable compositions and
bremsstrahlung radiation described herein may advantageously reduce the WOC
time, thereby reducing the cost associated with the cementing operation.
[0012] Unless otherwise indicated, all numbers expressing quantities of
ingredients, properties such as molecular weight, reaction conditions, and so
forth used in the present specification and associated claims are to be
understood as being modified in all instances by the term "about."
Accordingly,
unless indicated to the contrary, the numerical parameters set forth in the
following specification and attached claims are approximations that may vary
depending upon the desired properties sought to be obtained by the
embodiments described herein. At the very least, and not as an attempt to
limit
the application of the doctrine of equivalents to the scope of the claim, each
numerical parameter should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding techniques. It
should be noted that when "about" is at the beginning of a numerical list,
"about" modifies each number of the numerical list. Further, in some numerical
listings of ranges, some lower limits listed may be greater than some upper
limits listed. One skilled in the art will recognize that the selected subset
will
require the selection of an upper limit in excess of the selected lower limit.
[0013] FIG. 1 provides a cross-sectional illustration of a system suitable
for performing a cementing operation downhole. A surface casing 4, having a
wellhead 6 attached, is installed in a wellbore 2. A casing 8 is suspended
from
the wellhead 6, extends down the wellbore 2, and terminates with an open end
(or alternatively includes circulation ports in the walls of casing 8 (not
shown)).
An annulus 10 is defined between casing 8 and the wellbore 2. An annulus flow
3
CA 02898240 2015-07-14
. WO 2015/099875
PCT/US2014/061996
line 12 fluidly communicates with annulus 10 through the wellhead 6 and/or
surface casing 4 and includes an annulus valve 14. A flow line 16 fluidly
communicates with the inner diameter of casing 8 through the wellhead 6 and
includes a casing valve 18.
[0014] A settable composition may be pumped through the casing 8
and circulated up the annulus 10 while fluid returns are taken from the
annulus
out the annulus flow line 12, in a typical circulation direction. Alternately,
a
settable composition can be pumped into the annulus 10 from annulus flow line
12 while fluid returns are taken from the inner diameter of casing 8 through
the
10
flow line 16. Thus, fluid flows through wellbore 2 in a reverse circulation
direction.
[0015] In an alternate method a settable composition can be placed
within the wellbore 2 and a sealed or filled tubular can be lowered into the
wellbore 2 such that the settable composition is displaced into the annulus 10
area, thereby placing the settable composition within the annulus 10 without
pumping the settable composition into the annulus 10. The above method can be
referred to as puddle cementing. In some instances, the settable composition
can be a drilling fluid placed or left within the wellbore after drilling
operations
are complete.
[0016] In some embodiments, the settable composition is subjected to
a dose of radiation from bremsstrahlung photons. Bremsstrahlung radiation, or
simply bremsstrahlung, is electromagnetic radiation (e.g., photons) produced
by
the deceleration or deflection of charged particles (e.g., electrons) passing
through matter (e.g., a high-Z material) for example by interacting with the
strong electric fields of atomic nuclei. Bremsstrahlung radiation produces a
continuous photon energy spectrum (i.e., the resulting photons cover a whole
range of energy, from a maximum value downward through lower values all the
way to zero). In generating bremsstrahlung, some electrons that collide with
the
matter are decelerated to zero kinetic energy by a single head-on collision
with a
nucleus, and thereby have all their energy of motion converted at once into
photon radiation of maximum energy. Other electrons from the same incident
beam come to rest after being decelerated many times by the positively charged
nuclei. Each deflection and subsequent scattering of the electrons gives rise
to a
photon of less than maximum energy. The maximum energy of any one
4
CA 02898240 2015-07-14
' WO 2015/099875
PCT/US2014/061996
bremsstrahlung photon is the original kinetic energy of the incoming charged
particle, typically an electron in this embodiment.
[0017] Some embodiments described herein may involve irradiating a
settable composition with bremsstrahlung photons produced downhole (e.g.,
with an electron accelerator tool described herein) to facilitate setting of
the
settable composition. Bremsstrahlung-induced curing is a fast non-thermal
process that utilizes highly energetic electrons at controlled doses to
produce
photons that may be useful in facilitating setting of a settable composition
(e.g.,
for polymerizing and crosslinking polymeric materials).
[0018] FIG. 2 provides a cross-sectional illustration of a system 100 for
producing bremsstrahlung photons downhole in accordance with at least some
embodiments described herein. The system 100 includes an electron accelerator
tool 500 coupled to a wireline 401 and disposed in a wellbore 300 penetrating
a
subterranean formation 301. The wireline 401 may provide electrical power
transmission and communications between the electron accelerator tool 500 and
the surface of the wellbore. The tool wireline 401 may also bear the mass of
the
electron accelerator tool 500 during transit up and down the wellbore 300.
[0019] The electron accelerator tool 500 comprises a housing 501 for
containing at least some of the components of the electron accelerator tool
500.
The electron accelerator tool 500 may include accelerator electrical power
components 561. The electrical power components 561 may include devices for
allocating electrical power from the tool wireline 401 to the various power-
using
components throughout the electron accelerator tool 500.
[0020] The electron accelerator tool 500 may also include cooling
components 521 (e.g., cryogenic liquid with insulation) and communication
components 541. The communication components 541 may include devices for
communicating signals between the electron accelerator tool 500 and the
surface
of the wellbore.
[0021] Electron acceleration components 581 that provide/produce
accelerated electrons 601 (also referred to as high energy electrons) may also
be included in the electron accelerator tool 500. In some embodiments, a
linear
acceleration system that uses the abundant linear space within a casing to
amplify voltage may be used to produce the accelerated electrons 601. This
system, which may be engineered to possess a long, narrow shape makes it
amenable to downhole utility. In some embodiments, the accelerator may use
5
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
radiofrequency ("RF") power to produce the accelerated electrons 601. The
accelerator may be linear or a cyclotron accelerator. In some embodiments,
some or all of the following components may be operated: a high voltage power
supply, a magnetron or klystron, a high voltage switching circuit for pulsing,
waveguides for RF transfer, accelerating structures/cavities, an electron gun,
electron beam focusing/steering components, an electron beam target, an
electron beam dump, radiation shielding, pumps, and plumbing, and the like. In
some embodiments, wakefield technology that uses laser pulses to evacuate
electrons from small volumes of a solid (e.g., crystals) may be used to
produce
the accelerated electrons 601.
[0022] The devices that comprise the electron acceleration components
581 may vary based on the method of electron acceleration implemented (e.g.,
linear RF acceleration, cyclotron acceleration, or wakefield acceleration).
For
example, the electron acceleration components 581 may include lasers,
capacitors, diodes, and other devices for producing a plasma, RF induced
electromagnetic fields, and the like. In addition, the electron accelerator
tool
500, an electron acceleration component 581, or a portion thereof may have a
characteristic radius suitable for use in producing an electron beam.
[0023] In some embodiments, the accelerated electrons 601 may have
an energy ranging from a lower limit of about 0.1 MeV, 0.5 MeV, 1 MeV, or 5
MeV to an upper limit of about 50 MeV, 40 MeV, 30 MeV, 20 MeV, or 10 MeV,
wherein the energy of the electrons may range from any lower limit to any
upper
limit and encompasses any subset therebetween. In some embodiments, the
maximum intensity of the electron used produce bremsstrahlung photons may
be over 1014 electrons per second (e.g., up to about 6.25 x 1016 electrons per
second).
[0024] At least one of the electron acceleration components 581 may
include an electron beam port 591 where the accelerated electrons are expelled
from the electron acceleration component 581 and put on a trajectory to
impinge
upon a target 701 that converts the accelerated electrons 601 into
bremsstrahlung photons 801. In some embodiments, the target 701 may be a
converter material (e.g., a high-Z material having an atomic number of 70 and
above) within the housing 501. Examples of converter materials may include,
but are not limited to, tungsten, tantalum, rhenium, osmium, platinum,
thorium,
uranium, neptunium, lead, mercury, thallium, gold, iridium, iron, aluminum,
tin,
6
CA 02898240 2015-07-14
' WO 2015/099875
PCT/US2014/061996
and the like, and any combination thereof, including alloys comprising the
foregoing. In some embodiments, the target 701 may have a thickness that
ranges from a lower limit of about 1mm, 2 mm, 5 mm, or 10 mm to an upper
limit of about 100 mm, 50 mm, 25 mm, 10 mm, or 5 mm, wherein the target
thickness may range from any lower limit to any upper limit and encompasses
any subset therebetween.
[0025] In some embodiments, it may be desirable to create a trajectory
for the accelerated electrons 601 whereby they impinge upon the target 701 at
angles that are as perpendicular to the casing 302 as feasible. This
trajectory
may minimize the path length of the bremsstrahlung photons 801 though the
casing 302 and to the settable 303. As such, the position of the electron beam
port 591 and/or the target 701 may, in some embodiments, be positioned at
least substantially parallel to the radial plane of the electron accelerator
tool 500
and casing 302 (not shown). In some embodiments, the electron accelerator tool
500 may include an electron beam rastoring device 621 (e.g., an electromagnet)
to manipulate the trajectory of the accelerated electrons 601 to depart from
straight lines. In some embodiments, permanent magnets may be used to
manipulate the electron trajectory, either stationary or moved by a small
motor.
In some embodiments, the electron accelerator tool 500 may forego the use of
the rastoring device 621 and instead align the target 701 with the electron
beam
port 591 or increase the size of the target 701.
[0026] In some embodiments, the electron accelerator tool 500 may be
conveyed though the wellbore 300 or portions thereof in order to expose a
settable 303 disposed between the casing 302 and the wellbore 300 to
bremsstrahlung photons 801.
[0027] One skilled in the art will recognize that other configurations of
the system 100 may be implemented without departing from the scope of the
embodiments described herein.
[0028] FIG. 3 provides a cross-sectional illustration of a system 200 for
producing bremsstrahlung photons downhole in accordance with at least some
embodiments described herein. Similar to the system 100 of FIG. 1, the system
200 includes an electron accelerator tool 500 coupled to a wireline 401. The
electron accelerator tool 500 includes a housing 501, a cooling component 521,
a communication component 541, an electrical power component 561, an
electron acceleration component 581, and an electron beam port 591. However,
7
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
in FIG. 3, the electron beam port 591 is configured to be parallel to a casing
302
disposed in a wellbore 300 penetrating a subterranean formation 301.
[0029] In some embodiments, accelerated electrons 601 produced by
the electron acceleration components 581 may impinge the housing 501 and be
converted to bremsstrahlung photons 801. In some embodiments, accelerated
electrons 601 that pass through the housing 501 without being converted (not
shown) may be converted to bremsstrahlung photons 801 by interaction with the
drilling mud or the casing 302 (not shown).
[0030] The rate of setting for the settable composition may depend on,
inter alia, the dose of bremsstrahlung photons experienced by the settable
composition. In some embodiments, settable compositions may be subjected to
a bremsstrahlung radiation dose ranging from a lower limit of about 1 gray, 10
grays, or 100 grays to an upper limit of about 1000 grays, 750 grays, 500
grays,
or 250 grays, wherein the radiation dose may range from any lower limit to any
upper limit and encompasses any subset therebetween.
[0031] The bremsstrahlung radiation dose depends on the duration and
intensity of radiation exposure. The intensity of the bremsstrahlung photons
depends on, inter alia, the properties of the electron beam used in the
production of the bremsstrahlung photons. In some embodiments, the electron
beam and, consequently, the bremsstrahlung photons, may be generated
continuously. In some embodiments, the electron beam and the bremsstrahlung
photons may be generated in pulses. In either instances, the average current
of
the electron beam may range from a lower limit of about 10 microamps ("pA"),
50 pA, 100 pA, or 500 pA to an upper limit of about 10 milliamps ("mA"), 5 mA,
or 1 mA, wherein the average current of the electron beam may range from any
lower limit to any upper limit and encompasses any subset therebetween.
[0032] In a pulsed electron beam, the average current depends on the
characteristics of the pulses including, but not limited to, the pulse width,
the
peak current, and the repetition rate (i.e., pulses per second). One skilled
in the
art will recognize appropriate values for each of these suitable for producing
an
average current described herein.
[0033] The settable compositions that may be set with the systems and
methods described herein may include, but are not limited to, cements,
sealants, settable muds, lost circulation fluids, conformance fluids, and
combinations thereof).
8
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
[0034] Any cement suitable for use in subterranean applications may be
suitable for use in the embodiments described herein. The cementitious
compositions disclosed herein generally include water and a cement component
(e.g., a hydraulic cement that can include calcium, aluminum, silicon, oxygen,
and/or sulfur that sets and hardens by reaction with the water). As used
herein,
the term "cementitious composition" encompasses pastes (or slurries), mortars,
grouts (e.g., oil well cementing grouts), shotcrete, and concrete compositions
including a hydraulic cement binder. The terms "paste," "mortar," and
"concrete"
are terms of art: "pastes" are mixtures composed of a hydratable (or
hydraulic)
cement binder (usually, but not exclusively, Portland cement, Masonry cement,
Mortar cement, and/or gypsum, and may also include limestone, hydrated lime,
fly ash, granulated blast furnace slag, and silica fume or other materials
commonly included in such cements) and water; "mortars" are pastes
additionally including fine aggregate (e.g., sand); and "concretes" are
mortars
additionally including coarse aggregate (e.g., crushed rock or gravel). The
cement compositions described herein may be formed by mixing required
amounts of certain materials (e.g., a hydraulic cement, water, and fine and/or
coarse aggregate) as may be required for making a particular cementitious
composition.
[0035] Examples of hydraulic cements may include, but are not limited
to, Portland cements (e.g., Classes A, C, G, and H Portland cements),
pozzolana
cements, gypsum cements, phosphate cements, high alumina content cements,
silica cements, high alkalinity cements, and combinations thereof. Cements
including shale, cement kiln dust, or blast furnace slag also may be suitable
for
use in the some embodiments described herein. In certain embodiments, the
shale may include vitrified shale. In certain other embodiments, the shale may
include raw shale (e.g., unfired shale), or a mixture of raw shale and
vitrified
shale.
[0036] In some embodiments, a cementitious composition described
herein may include a polymerizable additive capable of undergoing
polymerization when subjected to radiation. In some embodiments, the
polymerizable additive may be present in an amount ranging from a lower limit
of about 0.01 /o, 0.10/0, 1%, or 5% by weight of the cement composition to an
upper limit of about 25%, 15%, or 10 /0 by weight of the cement composition,
9
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
wherein the amount of polymerizable additive may range from any lower limit to
any upper limit and encompasses any subset therebetween.
[0037] Examples of polymerizable additive may include, but are not
limited to, alkeneoxides, vinyl pyrrolidones, vinyl alcohols, acrylamides,
vinyl
methyl ethers, isobutylenes, fluoroelastomers, esters, tetrafluoroethylenes,
acetals, propylenes, ethylenes, methylpentenes, methylmethacrylates,
fluorinated ethylene propylenes, and the like, any derivative thereof, and any
combination thereof.
[0038] In some embodiments, a cementitious composition described
herein may also include a crosslinking agent capable of crosslinking a polymer
formed by the polymerization of the polymerizable additive. Examples of
crosslinking agent may include, but are not limited to, poly(ethylene glycol)
diacrylates, poly(ethylene glycol) dimethacrylates, trimethylolpropane
triacrylates (TMPTA), ethoxylated TMPTAs, trimethylolpropane trimethacrylates,
trimethylolpropanetriacrylates, hexanediol diacrylates, N,N-methylene
bisacrylam ides, hexanedioldivinylethers, triethyleneglycol
diacrylates,
pentaeritritoltriacrylates, tripropyleneglycol diacrylates, 1,3,5-trially1-
1,3,5-
triazine-2,4,6(1H,3H,5H)-triones, 2,4,6-triallyloxy-1,3,5-triazines,
alkoxylated
bisphenol A diacrylates, and the like, any derivative thereof, and any
combination thereof.
[0039] In some embodiments, a cementitious composition described
herein may also include a set retarder that lengthens the setting time of the
cementitious composition. In some instances, these set retarders allow a
cementitious composition to be pumped along long distances without the effect
of premature setting. In some embodiments, the set retarders may be present in
an amount ranging from a lower limit of about 0.01%, 0.1%, or 1% by weight of
the cement composition to an upper limit of about 10%, 5%, or 1% by weight of
the cement composition, wherein the amount of the set retarders may range
from any lower limit to any upper limit and encompasses any subset
therebetween.
[0040] Examples of set retarders may include, but are not limited to,
phosphonic acid, phosphonic acid derivatives, lignosulfonates, salts, sugars,
carbohydrate compounds, organic acids, carboxymethylated hydroxyethylated
celluloses, synthetic co- or ter-polymers including sulfonate and carboxylic
acid
groups, borate compounds, and the like, any derivative thereof, and any
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
combination thereof. In some embodiments, the set retarders may include
phosphonic acid derivatives, such as those described in U.S. Pat. No.
4,676,832.
Examples of suitable borate compounds may include, but are not limited to,
sodium tetraborate and potassium pentaborate. Examples of suitable organic
acids may include, but are not limited to, gluconic acid and tartaric acid.
[0041] In some embodiments, the set retarders may include a
sensitizer-containing retarder (e.g., a boron-containing retarder), also
referred
to as a sensitized retarder. In some embodiments, the sensitizer may comprise
a
material having a strong radiation absorption property. In some embodiments,
the sensitizer may be a scintillator material. In some embodiments, the
sensitizer may be any material that increases the capture efficiency of the
bremsstrahlung radiation within the cementitious composition. In some
embodiments, the sensitizer may be a boron-containing retarder, also referred
to as a boronated retarder. Examples of boronated retarders may include
boronated versions of the set retarders described above (e.g., a boronated
sugar, a boronated carbohydrate, a boronated glucose (e.g., 3-o-(o-carborany-
1-ylmethyl)-D-glucose presented in U.S. Pat. No. 5,466,679), and the like).
[0042] In some embodiments, a cementitious composition described
herein may include a set accelerator. As used herein, the term "set
accelerator"
can include any component, which reduces the setting time of a settable
composition.
[0043] In some embodiments, the set accelerators may be present in
an amount ranging from a lower limit of about 0.1%, 1%, or 5% by weight of
the cement composition to an upper limit of about 20%, 15%, or 100/0 by weight
of the cement composition, wherein the amount of the set accelerators may
range from any lower limit to any upper limit and encompasses any subset
therebetween.
[0044] Examples of set accelerators may include, but are not limited to,
alkali and alkali earth metal salts (e.g., calcium salts like calcium formate,
calcium nitrate, calcium nitrite, and calcium chloride), silicate salts,
aluminates,
amines (e.g., triethanolamine), and the like, any derivative thereof, and any
combination thereof.
[0045] In some embodiments, a cementitious composition described
herein may include oxidizing agents that degrade or otherwise deactivate the
set
retarder. In some embodiments, the oxidizing agents may be present in an
11
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
amount ranging from a lower limit of about 0.1%, 1%, or 5% by weight of the
cement composition to an upper limit of about 20%, 15%, or 10% by weight of
the cement composition, wherein the amount of the oxidizing agents may range
from any lower limit to any upper limit and encompasses any subset
therebetween.
[0046] Examples of oxidizing agents may include, but are not limited to,
alkaline earth and zinc salts of peroxide, perphosphate, perborate,
percarbonate; calcium peroxide, calcium perphosphate, calcium perborate,
magnesium peroxide, magnesium perphosphate, zinc perphosphate; calcium
hypochlorite, magnesium hypochlorite, chloramine T, trichloroisocyanuric acid,
trichloromelamine, dichloroisocynaurate dihydrate,
anhydrous
dichloroisocynaurate; and the like, any derivative thereof, and any
combination
thereof.
[0047] In some embodiments, a settable composition described herein
may be a sealant (e.g., a hardenable resin composition that comprises a liquid
hardenable resin and a hardening agent).
[0048] Selection of a suitable liquid hardenable resins may be affected
by the temperature of the subterranean formation to which the composition will
be introduced. By way of example, for subterranean formations having a bottom
hole static temperature ("BHST") ranging from about 60 F to about 250 F, two-
component epoxy-based resins comprising a hardenable resin component and a
hardening agent component in conjunction with specific hardening agents may
be preferred. For subterranean formations having a BHST ranging from about
300 F to about 600 F, a furan-based resin may be preferred. For subterranean
formations having a BHST ranging from about 200 F to about 400 F either a
phenolic-based resin or a one-component high-temperature epoxy-based resin
may be suitable. For subterranean formations having a BHST of at least about
175 F, a phenol/phenol formaldehyde/furfuryl alcohol resin may also be
suitable.
[0049] In some embodiments, the liquid hardenable resins may be
included in the hardenable resin compositions described herein in an amount
ranging from a lower limit of about 200/0, 30%, 40%, 50%, 60%, 70%, or 75%
by volume of the hardenable resin composition to an upper limit of about
900bo,
80%, or 75% by volume of the hardenable resin composition, and wherein the
amount may range from any lower limit to any upper limit and encompasses any
subset therebetween. It is within the ability of one skilled in the art with
the
12
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
benefit of this disclosure to determine how much of the liquid hardenable
resin
may be needed to achieve the desired results, which may depend on, inter alia,
the composition of liquid hardenable resin, the composition of the hardening
agent, and the relative ratios thereof.
[0050] As used herein, the term "hardening agent" refers to any
substance capable of transforming the liquid hardenable resin into a hardened,
consolidated mass. Examples of suitable hardening agents may include, but are
not limited to, aliphatic amines, aliphatic tertiary amines, aromatic amines,
cycloaliphatic amines, heterocyclic amines, amido amines, polyamides,
polyethyl
amines, polyether amines, polyoxyalkylene amines, carboxylic acids, carboxylic
anhydrides, triethylenetetraamine, ethylene diamine, N-cocoalkyltrimethylene,
isophorone diamine, N-aminophenyl piperazine, imidazoline,
1,2-
dia minocyclohexa ne, polyethera mine,
polyethyleneimines,
diethyltoluenediamine, 4,4'-diaminodiphenyl methane, methyltetrahydrophthalic
anhydride, hexahydrophthalic anhydride, maleic anhydride, polyazelaic
polyanhydride, phthalic anhydride, and combinations thereof. Examples of
commercially available hardening agents may include, but are not limited to
ETHACUREC)100 (75%-81% 3,5-diethyltoluene-2,4-diamine, 18%-20% 3,5-
diethyltoluene-2,6-diamine, and 0.5%-3% dialkylated m-phenylenediamines,
available from Albemarle Corp.) and JEFFAMINEC)D-230 (a polyetheramine,
available from Huntsman Corp.).
[0051] In some embodiments, the hardening agent may comprise a
mixture of hardening agents selected to impart particular qualities to the
resin-
based sealant composition. For example, in particular embodiments, the
hardening agent may comprise a fast-setting hardening agent and a slow-setting
hardening agent. As used herein, the terms "fast-setting hardening agent" and
"slow-setting hardening agent" do not imply any specific rate at which the
agents set a hardenable resin; instead, the terms merely indicate the relative
rates at which the hardening agents initiate hardening of the resin. Whether
as
particular hardening agent is considered fast-setting or slow-setting may
depend
on the other hardening agent(s) with which it is used. In a particular
embodiment, ETHACURE 100 may be used as a slow-setting hardening agent in
combination with JEFFAMINEDD-230 as a fast-setting hardening agent. In some
embodiments, the ratio of fast-setting hardening agent to slow-setting
hardening
agent may be selected to achieve a desired behavior of liquid hardening agent
13
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
component. For example, in some embodiments, the fast-setting hardening
agent may be at a ratio of approximately 1:5 by volume with the slow-setting
hardening agent. With the benefit of this disclosure, one of ordinary skill in
the
art should be able to select the appropriate ratio of hardening agents for use
in a
particular application.
[0052] In some embodiments, the hardening agent may be included in
the hardenable resin compositions in an amount sufficient to at least
partially
harden the liquid hardenable resin. In some embodiments, the hardening agents
may be included in the hardenable resin compositions described herein in an
amount ranging from a lower limit of about 1%, 5%, 100/0, 25%, or 50% by
volume of the liquid hardening agent to an upper limit of about 100%, 75%, or
50% by volume of the liquid hardening agent, and wherein the amount may
range from any lower limit to any upper limit and encompasses any subset
therebetween.
[0053] In some embodiments, the hardenable resin compositions may
further comprise at least one of a solvent (e.g., an aqueous diluent or
carrier
fluid), a silane coupling agent, an accelerator, and any combination thereof.
[0054] In some embodiments, a solvent may be added to the
hardenable resin compositions to reduce its viscosity for ease of handling,
mixing and transferring. However, in particular embodiments, it may be
desirable not to use such a solvent for environmental or safety reasons. It is
within the ability of one skilled in the art with the benefit of this
disclosure to
determine if and how much solvent may be needed to achieve a viscosity
suitable to the subterranean conditions of a particular application. Factors
that
may affect this decision include geographic location of the well, the
surrounding
weather conditions, and the desired long-term stability of the resin-based
seal
resulting from setting of the hardenable resin compositions.
[0055] Generally, any solvent that is compatible with the liquid
hardenable resin and that achieves the desired viscosity effect (e.g., degree
of
hardening) may be suitable for use in the hardenable resin composition.
Suitable
solvents may include, but are not limited to, polyethylene glycol, butyl
lactate,
dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dimethyl
formamide, diethylene glycol methyl ether, ethyleneglycol butyl ether,
diethyleneglycol butyl ether, propylene carbonate, d-limonene, fatty acid
methyl
esters, reactive diluents, and combinations thereof. Selection of an
appropriate
14
CA 02898240 2015-07-14
' WO 2015/099875
PCT/US2014/061996
solvent may be dependent on the compositions of the liquid hardenable resin,
the concentration of the liquid hardenable resin, and the composition of the
hardening agent. With the benefit of this disclosure, the selection of an
appropriate solvent should be within the ability of one skilled in the art. In
some
embodiments, the solvent may be included in the hardenable resin compositions
in an amount ranging from a lower limit of about 0.1%, 1%, or 5% by weight of
the liquid hardenable resin to an upper limit of about 50%, 40%, 30%, 20%, or
10% by weight of the liquid hardenable resin, and wherein the amount may
range from any lower limit to any upper limit and encompasses any subset
therebetween. Optionally, the liquid hardenable resin component may be heated
to reduce its viscosity, in place of, or in addition to using a solvent.
[0056] In some embodiments, the hardenable resin compositions
described herein may comprise an accelerator, which accelerates (e.g., via
catalysis) the onset and duration of hardening of the hardenable resin
compositions to the resin-based sealant composition. Suitable accelerators may
include, but are not limited to, organic or inorganic acids like maleic acid,
fumaric acid, sodium bisulfate, hydrochloric acid, hydrofluoric acid, acetic
acid,
formic acid, phosphoric acid, sulfonic acid, alkyl benzene sulfonic acids such
as
toluene sulfonic acid and dodecyl benzene sulfonic acid ("DDBSA"), phenols,
tertiary amines (e.g., 2,4,6-tris(dimethylaminomethyl)phenol, benzyl
dimethylamine, and 1,4-diazabicyclo[2.2.2]octane), imidazole and its
derivatives
(e.g., 2-ethyl,-4-methylimidazole, 2-methylimidazole, and 1-(2-cyanoethyl)-2-
ethyl-4-methylimidazole), Lewis acid catalysts (e.g., aluminum chloride, boron
trifluoride, boron trifluoride ether complexes, boron trifluoride alcohol
complexes, and boron trifluoride amine complexes), and the like, and any
combination thereof.
[0057] Some embodiments may involve introducing a settable
composition described herein into a wellbore penetrating a subterranean
formation; placing the settable composition in a portion of the wellbore, a
portion of the subterranean formation, or both; subjecting the settable
composition to bremsstrahlung photons at a radiation dose of about 1 gray to
about 1000 grays; and setting the settable composition therein. Some
embodiments for isolating a wellbore or a portion of a wellbore may include
pumping a settable composition containing a polymerizable additive into a
wellbore penetrating a subterranean formation; subjecting the settable
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
composition to bremsstrahlung photons at a radiation dose of about 1 gray to
about 1000 grays; and setting the settable composition therein.
[0058] Some embodiments may include preparing a cement
composition comprising: hydraulic cement, a polymerizable additive, and
sufficient water to form a slurry; placing the cement composition into the
wellbore; and subjecting the cement composition to bremsstrahlung photons at
a radiation dose of from about 1 gray to about 1000 grays to activate setting
of
the cement composition. In some embodiments, additives like a set retarder, a
set accelerator, an oxidizing agent, or combinations thereof may be added to
the
cement mixture, each independently before or after the water is added to the
mixture or during mixing.
[0059] In some embodiments, a settable composition described herein
may include a set retarder, a set accelerator, and an oxidizing agent. In some
embodiments, upon being exposed to the bremsstrahlung radiation, both the set
accelerator and oxidizer may be released or otherwise activated. The
simultaneous deactivation of the set retarder by the oxidizer and the
acceleration of cement hydration by the set accelerator provide a rapid
setting
time.
[0060] Embodiments disclosed herein include:
A. a method
that includes providing a settable composition in a portion
of a wellbore penetrating a subterranean formation, a portion of the
subterranean formation, or both; conveying an electron accelerator tool along
the wellbore proximal to the settable composition; producing an electron beam
in the electron accelerator tool with a trajectory that impinges a converter
material, thereby converting the electron beam to bremsstrahlung photons; and
irradiating the settable composition with the bremsstrahlung photons;
B.
a method that includes providing a settable composition in a portion
of a wellbore penetrating a subterranean formation, a portion of the
subterranean formation, or both; conveying an electron accelerator tool along
the wellbore proximal to the settable composition; producing a pulsed electron
beam in the electron accelerator tool with a trajectory that impinges a
converter
material, thereby converting the pulsed electron beam to bremsstrahlung
photons, wherein the pulsed electron beam has an average current of about 10
microamps to about 10 milliamps; and irradiating the settable composition with
the bremsstrahlung photons; and
16
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
C.
a method that includes providing a settable composition in a portion
of a wellbore penetrating a subterranean formation, a portion of the
subterranean formation, or both; conveying an electron accelerator tool along
the wellbore proximal to the settable composition; producing an electron beam
in the electron accelerator tool with a trajectory that impinges a converter
material that is a portion of a housing of the electron accelerator tool,
thereby
converting the electron beam to bremsstrahlung photons, wherein the electron
beam has an average current of about 10 microamps to about 10 milliamps; and
irradiating the settable composition with the bremsstrahlung photons.
[0061] Each of embodiments A, B, and C may have one or more of the
following additional elements in any combination (unless already provided
for):
Element 1: the method further including manipulating the trajectory of the
electron beam with a rastoring device; Element 2: wherein the electron beam is
continuous; Element 3: wherein the electron beam is pulsed; Element 4:
wherein the electron beam comprises electrons having an energy of about 0.5
MeV to about 50 MeV; Element 5: wherein the electron beam has an average
current of about 10 microamps to about 10 milliamps; Element 6: wherein the
converter material comprises at least one of: tungsten, tantalum, rhenium,
osmium, platinum, thorium, uranium, neptunium, lead, mercury, thallium, gold,
iridium, iron, aluminum, tin, and any combination thereof; Element 7: wherein
the converter material comprises a material having an atomic number greater
than 70; Element 8: wherein the converter material is a portion of a housing
of
the electron accelerator tool; Element 9: wherein the converter material has a
thickness of about 1 mm to about 1 cm; Element 10: wherein the converter
material is a portion of a casing disposed in the wellbore, and wherein the
settable composition is disposed within an annulus of the casing and the
wellbore; Element 11: wherein the settable composition is a cement; Element
12: wherein the settable composition is a sealant; Element 13: wherein the
settable composition is at least one of: a settable mud, a lost circulation
fluid, a
conformance fluid, and any combination thereof; and Element 14: wherein the
settable composition comprises at least one of: a set accelerator, a set
retarder,
a polymerizable additive, an oxidizing agent, and any combination thereof.
[0062] By way of non-limiting example, exemplary combinations
applicable to A, B, C include:
17
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
[0063] Element 1 in combination with one of Elements 2-3; at least one
of Elements 4-5 in combination with one of Elements 2-3; at least one of
Elements 6-7 in combination with one of Elements 2-3 and optionally in
combination with Element 1; Element 9 in combination with at least one of
Elements 6-7; Element 9 in combination with one of Elements 2-3 and optionally
in combination with Element 1; Element 8 or 10 in combination with any of the
foregoing; Element 8 or 10 in combination with at least one of Elements 1-7;
Element 8 or 10 in combination with Element 9 and optionally in combination
with at least one of Elements 1-7; one of Elements 11-14 in combination with
any of the foregoing; two or more of Elements 11-14 in combination; and at
least one of Elements 1-14 in combination with at least one of Elements 1-10.
[0064] The embodiments described herein may also be useful for or
adapted for cement or concrete in other applications, including infrastructure
and building materials, where a quick setting time can be obtained with the
polymer system. Some specific examples include rapid hardening of pre-cast
units such as pipes, panels, and beams, cast in-situ structures for bridges,
dams, or roads, quick-set grout, increased adhesion in cement, addition of
water-resistant properties to cement, decorative concrete, rapid concrete
repair,
production of cement board. Other advantages over typical polymer-enhanced
concrete systems include the ability to use a wider variety of polymer
species,
including oligomers which are significantly less volatile, combustible and
toxic,
and the elimination of initiators, which are also toxic to humans and the
environment.
[0065] To facilitate a better understanding of the embodiments
described herein, the following examples of preferred or representative
embodiments are given. In no way should the following examples be read to
limit, or to define, the scope of the embodiments described herein.
EXAMPLES
[0066] Example I: Cement slurry samples were prepared by mixing the
following ingredients: 400 grams of a class H cement (Lafarge, Joppa IL), 160
grams of water (w/c = 0.40), 8.0% by weight of solids (bwos) acrylamide,
0.42% bwos N,N-methylene-bis-acrylamide as a crosslinker, 0.50 % bwos
maltodextrin as a set retarder, 0.50% bwos HR -25 as a set retarder (a high-
temperature retarder available from Halliburton Energy Services, Inc.), 0.20 %
18
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
bwos Diutan gum as a rheology modifier, 0.10% bwos SnCl2 as an oxygen
scavenger, and 1.0% bwos SYLOID RAD 2105 silica gel (Grace Performance
Chemicals, USA).
[0067] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule. The slurry was split into two samples. One sample
was exposed for 20 seconds to bremsstrahlung radiation produced by focusing
an electron beam of 5-6MeV energy onto a tungsten target and placing the
sample in a vial at the other end of the tungsten target and thereby exposing
the sample to the bremsstrahlung photons. The other sample was not irradiated
and kept as a control. The control sample remained fluid. The irradiated
sample
had been crosslinked and displayed a freestanding solid-like behavior.
[0068] Example 2: A cement/sand slurry was prepared similar to that of
Example 1, except that the 1% SYLOID RAD particles were not included, and
200 grams of the class H cement was replaced with 200 mesh sand for a 50:50
mixture of cement and silica flour.
[0069] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule. The slurry was split into two samples. One sample
was exposed for 30 seconds to bremsstrahlung radiation produced by focusing
an electron beam of 5-6MeV energy onto a tungsten target and placing the
sample in a vial at the other end of the tungsten target and thereby exposing
the sample to the bremsstrahlung photons. The other sample was not irradiated
and kept as a control. The control sample remained fluid. The irradiated
sample
had been crosslinked and displayed a freestanding solid-like behavior.
[0070] Example 3: Silica flour slurry samples were prepared by mixing
the following ingredients: 400 grams of SSA-1 silica flour (Halliburton,
Houston,
Texas) 168 grams of water (w/c = 0.42), 0.18wt% Ca(OH)2 per 100 grams
water, 8.0% by weight of solids (bwos) acrylamide, 0.42% bwos N,N-
methylene-bis-acrylamide as a crosslinker, 0.20% bwos diutan gum as a
rheology modifier, and 0.10% bwos SnCl2 as an oxygen scavenger.
[0071] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule. The slurry was split into two samples. One sample
was exposed for 30 seconds to bremsstrahlung radiation produced by focusing
an electron beam of 5-6 MeV energy onto a tungsten target and placing the
sample in a vial at the other end of the tungsten target and thereby exposing
the sample to the bremsstrahlung photons. The other sample was not irradiated
19
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
and kept as a control. The control sample remained fluid. The irradiated
sample
had been crosslinked and displayed a freestanding solid-like behavior.
[0072] The samples demonstrate that bremsstrahlung radiation may be
utilized to solidify cement by irradiating a sample of polymerizable additive
contained in the cement.
[0073] Example 4: Cement slurry samples were prepared by mixing the
following ingredients: 800 grams of a class H cement, 320 grams of water, 8.0%
bwos acrylamide, 0.42% bwos N,N-methylene-bis-acrylamide as a crosslinker,
0.50% bwos maltodextrin as a set retarder, 0.50% bwos HR-25 as a set
retarder, 0.20% bwos diutan gum as a rheology modifier, 1.0% bwos SnCl2 as
an oxygen scavenger, and 1.0% bwos SYLOID RAD 2105.
[0074] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule and portioned into 1 inch x 2 inch plastic vials.
The
vials were subjected to bremsstrahlung radiation produced by focusing an
electron beam of about 5 MeV energy and an average current of 75 pA (5 ps
pulse width, 0.05 A peak current, and 300 pulses per second ("pps") duty
cycle)
that passed through a tungsten target of varying thickness and a 1/2 inch
thick
carbon steel pipe. A dosimeter was affixed to the cement vials to measure the
radiation dose. Table 1 provides the dose rate (i.e., dose divided by exposure
time) for tungsten target thickness of 2 mm to 25 mm that shOws as the
thickness of the tungsten target increases the dose rate decreases.
Table 1
R Tungsten Target Dose Rate
un #
Thickness (mm) (cGy/sec)
1 0 6593
2 2 6690
3 3 6669
4 3 6535
5 5 5059
6 25 934
7 25 925
[0075] After exposure to the bremsstrahlung radiation, the samples at
(1) the side closest to the radiation and (2) the side furthest from the
radiation
were analyzed for Shore hardness. Table 2 provides the Shore hardness results.
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
Table 2
Tungsten Target Exposure Time Shore Hardness
Shore Hardness
(side closest to (side furthest
from
Thickness (mm) (seconds) radiation) radiation)
0 3.3 73 47
2 3.3 79 68
2 3.3 79 60
3 3.3 79 71
3 3.3 75 71
3 3.3 80 67
3 3.3 75 58
3.3 72 66
10 79 57
25 10 77 64
25 6.6
* Unable to measure because not hardened/set.
5
[0076] This example demonstrates while the dose rate may decrease
with increasing tungsten target thickness, the exposure time can be adjusted
to
provide comparable setting/hardening.
[0077] Example 5: Cement slurry samples were prepared by mixing the
following ingredients: 800 grams of a class H cement, 320 grams of water, 8.0%
10 bwos acrylamide, 0.42% bwos N,N-methylene-bis-acrylamide as a
crosslinker,
0.50% bwos maltodextrin as a set retarder, 0.500/0 bwos HR-25 as a set
retarder, 0.05% bwos diutan gum as a rheology modifier, 1.00/0 bwos SnCl2 as
an oxygen scavenger, and 1.0 /0 bwos SYLOID RAD 2105.
[0078] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule and portioned into 1 inch x 2 inch plastic vials.
The
vials were subjected to bremsstrahlung radiation produced by focusing an
electron beam of about 7.5 MeV energy and a varied average current produced
by changing the pulse width (0.1 A peak current and 250 pps duty cycle) that
passed through a 3 mm tungsten target and a 1/2 inch thick carbon steel pipe.
After exposure to the bremsstrahlung radiation, the samples at (1) the side
closest to the radiation and (2) the side furthest from the radiation were
analyzed for Shore hardness. Table 3 provides the Shore hardness results.
21
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
Table 3
A Shore Shore
verage
Exposure Time Pulse Width
Hardness (side Hardness (side
Current
(seconds) (ps) closest to
furthest from
([1A) radiation) radiation)
3 4 100 76 47
12 1 25 90 83
12 1 25 72 69
12 1 25 87 71
6 1 25 78 58
6 1 25 75 54
[0079] The 12 second exposure, 1 ps pulse width as compared to the 3
second exposure, 4 ps pulse width has 1/4 the exposure time but 4 times the
pulse width, so substantially the same radiation dose. However, the longer
exposure time appears to provide improved hardening/setting of the cement
slurry.
[0080] Example 6: Cement slurry samples were prepared by mixing the
following ingredients: 800 grams of a class H cement, 320 grams of water, 8.0%
bwos acrylamide, 0.42% bwos N,N-methylene-bis-acrylamide as a crosslinker,
0.50% bwos maltodextrin as a set retarder, 0.50% bwos HR-25 as a set
retarder, 0.05% bwos diutan gum as a rheology modifier, 1.0% bwos SnCl2 as
an oxygen scavenger, and 1.0% bwos SYLOID RAD 2105.
[0081] The slurry was mixed for 45 seconds on a Waring blade mixer as
per the API mixing schedule and portioned into 1 inch x 2 inch plastic vials.
The
vials were subjected to bremsstrahlung radiation produced by focusing an
electron beam of about 7.5 MeV energy and a varied average current produced
by changing the peak current (4 ps pulse width and 250 pps duty cycle) that
passed through a 3 mm tungsten target and a 1/2 inch thick carbon steel pipe.
After exposure to the bremsstrahlung radiation, the samples at (1) the side
closest to the radiation and (2) the side furthest from the radiation were
analyzed for Shore hardness. Table 4 provides the Shore hardness results.
Table 4
22
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
A Shore Shore
verage
Exposure Time Peak Current Hardness (side Hardness
(side
Current
(seconds) (A) closest to furthest
from
(wok) radiation)
radiation)
3 0.10 100 76 62
3 0.10 100 80 63
3 0.10 100 76 64
3 0.10 100 74 64
3 0.10 100 73 59
2 0.025 25 59
4 0.025 25 74 54
4 0.025 25 75 56
6 0.025 25 76 59
12 0.025 25 88 73
* Unable to measure because not hardened/set.
[0082] This example demonstrates that duty cycle tradeoffs towards a
greater total number of pulses in combination with a lower peak current (i.e.,
a
lower average current) appears to be advantageous in downhole applications.
[0083] Therefore, the embodiments described herein are 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
embodiments described herein 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, combined, or modified and all such variations
are considered within the scope and spirit of the embodiments described
herein.
The embodiments illustratively disclosed herein suitably may be practiced in
the
absence of any element that is not specifically disclosed herein and/or any
optional element disclosed herein. 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. All numbers and ranges
disclosed above may vary by some amount. Whenever a numerical range with a
lower limit and an upper limit is disclosed, any number and any included range
23
CA 02898240 2015-07-14
WO 2015/099875
PCT/US2014/061996
falling within the range is specifically disclosed. In particular, every range
of
values (of the form, "from 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. Moreover, the indefinite articles "a" or "an," as used in the
claims, are
defined herein to mean one or more than one of the element that it introduces.
If there is any conflict in the usages of a word or term in this specification
and
one or more patent or other documents that may be incorporated herein by
reference, the definitions that are consistent with this specification should
be
adopted.
24
