Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS AND METHODS FOR IN SITU MONITORING OF CEMENT SLURRY
LOCATIONS AND SETTING PROCESSES THEREOF
BACKGROUND
[0001] The present invention relates to optical analysis systems and
methods for analyzing fluids and, in particular, to systems and methods for
monitoring fluids relating to cementing operations in or near real-time.
[0002] Cementing operations are often used in wellbores for, inter alia,
supporting casings and liners, providing zonal isolation, and protecting the
casing from corrosive formation fluids. In such operations, it is often
important
to precisely know the location, characteristics, and setting status of cement
slurries as they circulate and set in wellbores or other annuli therein. In
situ
analysis of cement slurries during cementing operations is often not
achievable
with conventional monitoring systems, which are incapable of operation in
extreme environments such as downhole applications. Accordingly, the location,
characteristics, and setting status of cement slurries are often required to
be
extrapolated from laboratory data, calculations of volumes to be filled, and
calculations based on the conditions in the wellbore (e.g., temperature).
[0003] After the cementing operation has completed, the location,
characteristics, and setting status of cement slurry (or set cement) can be
analyzed via logging techniques, which are time-consuming and costly. For
example, if the cementing operation was successfully performed (e.g., the
proper locations were cemented) and the cement is sufficiently set, subsequent
subterranean operations can be performed (e.g., drilling operations,
fracturing
operations, completion operations, and the like). However, if an aspect of the
cementing operation was incorrect, remedial operations are often necessary.
[0004] For example, if the cement is not sufficiently set, the operator
allows for additional setting time and then runs another logging operation,
which
further contributes to costs and nonproductive time.
[0005] In another example, if too much cement slurry was added, a
drill-out operation may be required, which is particularly prevalent in
reverse
cementing where the cement is pumped from the annulus side. In other
instances, if too little cement slurry was added, another cementing operation
may be needed.
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,
[0006] These issues can be especially complex in normal primary
cementing operations where the cement slurry is pumped down the casing and
up the annulus. Generally, the cement slurry formulations are designed so that
the 'lead' slurry (i.e., uppermost slurry after placement in the annulus) is
of
lower density than the 'tail' slurry that is the bottommost slurry placed near
the
bottom of the annulus. Proper placement of the 'lead' slurry behind casing and
the sufficient setting of the cement near the casing shoe (i.e., near the
bottom
of the casing) are important for the casing to withstand pressures of the
initial
pressure test and subsequent drilling that are performed.
[0007] In other cementing operations, e.g., some remedial operations
to plug thief zones, two fluids are used that when contacted viscosify and
plug
high permeability regions in the wellbore. Pumping calculated volumes is often
insufficient to assure operation efficacy, which can lead to additional
remedial
operations and the use of high volumes of expensive fluids. Accordingly, in
situ
monitoring of the location of each of these fluids may reduce the cost and
time
associated with such remedial cementing operations.
[0008] As a whole, cementing operations are often performed multiple
times during the lifetime of a well. Therefore, in situ analysis of cement
slurries
and/or set cements may have a compounding effect on reducing the cost and
time associated with the drilling and maintenance of a well.
SUMMARY OF THE INVENTION
[0009] The present invention relates to optical analysis systems and
methods for analyzing fluids and, in particular, to systems and methods for
monitoring fluids relating to cementing operations in or near real-time.
[0010] One embodiment of the present invention is a method that
comprises containing a cement slurry within a flow path, the cement slurry
having a chemical reaction occurring therein; and optically interacting the
cement slurry with an integrated computational element, thereby generating an
output signal corresponding to a characteristic of the chemical reaction.
[0011] Another embodiment of the present invention is a method that
comprises flowing a series of fluids through a flow path, the series of fluids
comprising a spacer fluid followed by a cement slurry; and optically
interacting
at least one of the series of fluids with an integrated computational element,
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thereby generating an output signal corresponding to a characteristic of the
at
least one of the series of fluids.
[0012] Yet another embodiment of the present invention is a system
that comprises a flow path containing a cement slurry; and at least two
optical
computing devices arranged in the flow path for monitoring the cement slurry,
each of the at least two optical computing devices independently having at
least
one integrated computational element configured to optically interact with the
cement slurry and thereby generate optically interacted light, and at least
one
detector arranged to receive the optically interacted light and generate an
output signal corresponding to a characteristic of the cement slurry.
[0013] The features and advantages of the present invention will be
readily apparent to those skilled in the art upon a reading of the description
of
the preferred embodiments that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The following figures are included to illustrate certain aspects of
the present invention, 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.
[0015] FIG. 1 illustrates an exemplary integrated computation element,
according to one or more embodiments.
[0016] FIG. 2 illustrates a block diagram non-mechanistically
illustrating how an optical computing device distinguishes electromagnetic
radiation related to a characteristic of interest from other electromagnetic
radiation, according to one or more embodiments.
[0017] FIGS. 3A-B illustrate an exemplary system for monitoring a
fluid, according to one or more embodiments.
[0018] FIG. 4 illustrates another exemplary system for monitoring a
fluid, according to one or more embodiments.
DETAILED DESCRIPTION
[0019] The present invention relates to optical analysis systems and
methods for analyzing fluids and, in particular, to systems and methods for
monitoring fluids relating to cementing operations in or near real-time.
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[0020] The exemplary systems and methods described herein employ
various configurations of optical computing devices, also commonly referred to
as "opticoanalytical devices," for the real-time or near real-time monitoring
of
fluids in order to ascertain the location of a cement slurry and/or the status
of a
cement setting process. In operation, the exemplary systems and methods may
be useful and otherwise advantageous in determining that a cement slurry has
been properly placed, for example, in a wellbore, by monitoring a
characteristic
of the cement slurry and/or a spacer fluid introduced into the wellbore before
or
after the cement slurry. In other embodiments, the systems and methods may
provide a real-time or near real-time determination of cement setting process
kinetics, including the concentration of unreacted reagents and/or resultant
products.
[0021] The optical computing devices, which are described in more
detail below, can advantageously provide real-time or near real-time
monitoring
of a cement slurry or other fluid relating thereto (e.g., a spacer fluid) and
chemical reactions occurring therein that cannot presently be achieved with
either onsite analyses at a job site or via more detailed analyses that take
place
in a laboratory. A significant and distinct advantage of these devices is that
they
can be configured to specifically detect and/or measure a particular
characteristic of interest of a fluid or other material, thereby allowing
qualitative
and/or quantitative analyses of the fluid to occur without having to extract a
sample and undertake time-consuming analyses at an off-site laboratory. With
the ability to undertake real-time or near real-time analyses, the exemplary
systems and methods described herein may be able to provide some measure of
proactive or responsive control over the cement slurry location, provide some
measure of cement slurry loss into the subterranean formation as an indicator
of
wellbore damage, eliminate time-consuming wireline operations that analyze the
progress of the setting processes of cement slurries, mitigate drill-out
operations
as a result of excess cement slurry introduction into the wellbore, enable the
collection and archival of information relating to cement setting processes in
conjunction with operational information to optimize subsequent operations,
and/or enhance the capacity for remote job execution.
[0022] Those skilled in the art will readily appreciate that the systems
and methods disclosed herein may be suitable for use in the oil and gas
industry
since the described optical computing devices provide a relatively low cost,
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rugged, and accurate means for monitoring fluids and chemical reactions
occurring therein in order to facilitate the efficient management of wellbore
operations involving cement slurries. It will be further appreciated, however,
that the various disclosed systems and methods are equally applicable to other
technology or industry fields including, but not limited to, the construction
industry, industrial applications, mining industries, or any field where it
may be
advantageous to determine in real-time or near real-time the status of the
cement setting processes or other similar chemical reactions.
[0023] The optical computing devices suitable for use in the present
embodiments can be deployed at any number of various points within a flow
path to monitor a fluid, including, the location of a cement slurry, the
location of
a spacer fluid introduced before or after a cement slurry, and/or the status
of
the cement setting process. It should be noted that the location of a material
of
interest can be derived from detecting a characteristic of interest with an
optical
computing device having a known location (approximate or exact) or using two
or more optical computing devices having known relative locations to each
other.
Depending on the location of the particular optical computing device, various
types of information about the cement slurry can be ascertained. In some
cases,
for example, the optical computing devices can be used to monitor a chemical
reaction in real-time that relates to cement setting processes, for example,
by
determining the concentration of unreacted reagents and any resulting products
relating to the cement setting process. This may prove advantageous in
determining when the cement setting process has progressed to completion. It
is
known to those skilled in the art that while true completion of cement
hydration
may take a long time often extending into months, for the purpose of cementing
operations (e.g., subterranean cementing operations), the completion of cement
hydration is taken as that phase in cement hydration at which point the
strength
development values (e.g., compressive strength) reach a plateau value, which
may, in some instance, take about 2 to about 28 days. In some embodiments,
the cement hydration level and indication of strength may be characterized by
the concentration cement hydration products, e.g., calcium hydroxide or
calcium
silicate hydrates in the case of Portland cements. Thus, the systems and
methods described herein may be configured to monitor a fluid and a chemical
reaction processes related thereto.
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[0024] As used herein, the term "fluid" refers to any substance that is
capable of flowing, including particulate solids, liquids, gases, slurries,
emulsions, powders, muds, glasses, combinations thereof, and the like. In some
embodiments, the fluid can be an aqueous fluid, including water or the like.
In
some embodiments, the fluid can be a non-aqueous fluid, including organic
compounds, more specifically, hydrocarbons, oil, a refined component of oil,
petrochemical products, and the like. In some embodiments, the fluid can be a
treatment fluid (e.g., a spacer fluid, a cement fluid composition, a lost
circulation
treatment fluid, and the like) or a formation fluid as found in the oil and
gas
industry. Fluids can include various flowable mixtures of solids, liquids,
and/or
gases. Illustrative gases that can be considered fluids according to the
present
embodiments include, for example, air, nitrogen, carbon dioxide, argon,
helium,
hydrogen sulfide (H2S), methane, ethane, butane, and other hydrocarbon gases,
combinations thereof and/or the like.
[0025] As used herein, the term "cement fluid composition" refers to
any fluid that comprises a cement. Cement is not necessarily hydraulic cement,
since other types of materials (e.g., polymers like epoxies and latexes) can
be
used in place of, or in addition to, a hydraulic cement. Examples of cements
may
include, but are not limited to, hydraulic cements, Portland cement, gypsum
cements, calcium phosphate cements, high alumina content cements, silica
cements, high alkalinity cements, shale cements, acid/base cements, magnesia
cements (e.g., Sorel cements), fly ash cements, zeolite cement systems, cement
kiln dust cement systems, slag cements, micro-fine cements, epoxies,
bentonites, latexes, and the like, any derivative thereof, and any combination
thereof. Cement fluid compositions may be cement slurries that include water
or
dry cement blends. Unless otherwise specified, the term "fluid" encompasses
cement fluid compositions, the term "cement fluid compositions" encompasses
cement slurries and dry cement blends, and the term "cement slurry"
encompasses foamed cements. As used herein, the term "dry cement blend"
refers to a mixture of solid particles including at least some cement
particles and
is not hydrated beyond about ambient conditions (e.g., no additional water has
been added).
[0026] As used herein, the term "chemical reaction process" or
"chemical reaction" refers to a process that leads to the transformation of
one
set of chemical substances to another. As known to those skilled in the art,
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chemical reactions involve one or more reagents, as described below, that
chemically react either spontaneously, requiring no input of energy, or non-
spontaneously typically following the input of some type of energy, such as
heat,
light, or electricity. The chemical reaction process yields one or more
products,
which may or may not have properties different from the reagents.
[0027] As used herein, the term "cement setting process" refers to the
chemical reaction(s) that cause a cement slurry to harden into a cement.
Chemical reactions of cement setting processes described herein may include,
but are not limited to, hydration reactions (e.g., reactions between hydraulic
cements and water), crosslinking reactions (e.g., polymer crosslinking
reactions
and reactions between 2-component epoxies), and the like, and any combination
thereof. As used herein, the term "hydraulic cement" refers to a cement that
hardens in the presence of water. Changes in characteristics that may be
useful
in providing the status of a cement setting process may include, but are not
limited to, an increase in particle size, a plateau of an exothermic reaction,
a
decrease in the concentration of a reagent (e.g., water), an increase in the
concentration of a product (e.g., a base like calcium hydroxide), and the
like,
and any combination thereof.
[0028] As used herein, the term "cementing operation" encompasses
any subterranean operation using a cement slurry, e.g., primary cementing
operations, secondary cementing operations, squeeze operations, remedial
cementing operations, casing operations, plugging operations (e.g., relative
to
thief zones), lost circulation operations, zonal isolation operations, and the
like
including any with traditional or reverse fluid flow directions.
[0029] As used herein, the term "characteristic" refers to a chemical,
mechanical, or physical property (quantitative or qualitative) of a material
of
interest (e.g., a spacer fluid, a cement fluid composition, a lost circulation
treatment fluid, and the like) or analyte thereof. As used herein, the term
"analyte" refers to a chemical component of the material of interest. The term
analyte encompasses both chemical components involved in a chemical reaction
(e.g., reagents and products) and chemical components not involved in a
chemical reaction transpiring within the material of interest. Illustrative
characteristics of a material of interest that can be monitored with the
optical
computing devices disclosed herein can include, for example, chemical
composition (e.g., identity and concentration in total or of individual
analytes),
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impurity content, pH, viscosity, density, ionic strength, total dissolved
solids, salt
content, porosity, opacity, bacteria content, particle size distribution,
color,
temperature, hydration level, oxidation state, and the like. Moreover, the
phrase
"characteristic of interest" may be used herein to refer to a characteristic
of the
cement slurry or analyte thereof, a characteristic of a spacer fluid or
analyte
thereof, and/or a characteristic of a chemical reaction transpiring or
otherwise
occurring therein.
[0030] Exemplary analytes may include, but are not limited to, water,
salts, minerals (wollastonite, metakaolin, and pumice), cements (Portland
cement, gypsum cements, calcium phosphate cements, high alumina content
cements, silica cements, and high alkalinity cements), fillers (e.g., fly ash,
fume
silica, hydrated lime, pozzolanic materials, sand, barite, calcium carbonate,
ground marble, iron oxide, manganese oxide, glass bead, crushed glass, crushed
drill cutting, ground vehicle tire, crushed rock, ground asphalt, crushed
concrete,
crushed cement, ilmenite, hematite, silica flour, fume silica, fly ash,
elastomers,
polymers, diatomaceous earth, a highly swellable clay mineral, nitrogen, air,
fibers, natural rubber, acrylate butadiene rubber, polyacrylate rubber,
isoprene
rubber, chloroprene rubber, butyl rubber, brominated butyl rubber, chlorinated
butyl rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene
copolymer rubber, sulphonated polyethylene, ethylene acrylate rubber,
epichlorohydrin ethylene oxide copolymer, ethylene propylene rubber, ethylene
propylene diene terpolymer rubber, ethylene vinyl acetate copolymer,
flourosilicone rubber, silicone rubber, poly-
2,2,1-bicycloheptene
(polynorbomeane), alkylstyrene, crosslinked substituted vinyl acrylate
copolymer, nitrile rubber (butadiene acrylonitrile copolymer), hydrogenated
nitrile rubber, fluoro rubber, perfluoro rubber,
tetraflouroethylene/propylene,
starch polyacrylate acid graft copolymer, polyvinyl alcohol cyclic acid
anhydride
graft copolymer, isobutylene maleic anhydride, acrylic acid type polymer,
vinylacetate-acrylate copolymer, polyethylene oxide polymer, carboxymethyl
cellulose polymer, starch-polyacrylonitrile graft copolymer, polymethacrylate,
polyacrylamide, and non-soluble acrylic polymer), hydrocarbons, acids, acid-
generating compounds, bases, base-generating compounds, biocides,
surfactants, scale inhibitors, corrosion inhibitors, gelling agents,
crosslinking
agents, anti-sludging agents, foaming agents, defoaming agents, antifoam
agents, emulsifying agents, de-emulsifying agents, iron control agents,
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proppants or other particulates, gravel, particulate diverters, salts, cement
slurry
loss control additives, gas migration control additives, gases, air, nitrogen,
carbon dioxide, hydrogen sulfide (H2S), argon, helium, hydrocarbon gases,
methane, ethane, butane, catalysts, clay control agents, chelating agents,
corrosion inhibitors, dispersants, flocculants, scavengers (e.g., H2S
scavengers,
CO2 scavengers, or 02 scavengers), lubricants, breakers, delayed release
breakers, friction reducers, bridging agents, viscosifiers, weighting agents,
solubilizers, rheology control agents, viscosity modifiers, pH control agents
(e.g.,
buffers), hydrate inhibitors, relative permeability modifiers, diverting
agents,
consolidating agents, fibrous materials, bactericides, tracers, probes,
nanoparticles, paraffin waxes, asphaltenes, foams, sand or other solid
particles,
and the like. Combinations of these components can be used as well.
[0031] As used herein, the term "flow path" refers to a route through
which a fluid is capable of being transported between two points. In some
cases,
the flow path need not be continuous or otherwise contiguous between the two
points. Exemplary flow paths include, but are not limited to, a slurry tank, a
flowline, a pipeline, a conduit, a wellbore annulus (e.g., an annulus between
a
casing and a wellbore or an annulus between a screen and a wellbore), a
casing,
a liner, a liner string, a hose, a mixer, a pump, a process facility, a
storage
vessel, a tanker, a railway tank car, a transport barge or ship, a separator,
a
contactor, a process vessel, and the like, any hybrid thereof, and any
combination thereof. In cases where the flow path is a pipeline, or the like,
the
pipeline may be a pre-commissioned pipeline or an operational pipeline. It
should be noted that the term "flow path" does not necessarily imply that a
fluid
is flowing therein, rather that a fluid is capable of being transported or
otherwise
flowable therethrough. In some embodiments, a flow path may be a component
of a more complex system, for example, skids, trucks, pumps, and the like. In
some embodiments, a flow path may comprise more than one section that is
separated, but still fluidly communicable, by apparatuses like valves, flow
meters, and the like.
[0032] As used herein, the term "electromagnetic radiation" refers to
radio waves, microwave radiation, infrared and near-infrared radiation,
visible
light, ultraviolet light, X-ray radiation, and gamma ray radiation.
[0033] As used herein, the term "optical computing device" refers to an
optical device that is configured to receive an input of electromagnetic
radiation
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from a fluid or analyte thereof and produce an output of electromagnetic
radiation from a processing element arranged within the optical computing
device. The processing element may be, for example, an integrated
computational element (ICE) used in the optical computing device. As discussed
in greater detail below, the electromagnetic radiation that optically
interacts with
the processing element is changed so as to be readable by a detector, such
that
an output of the detector can be correlated to at least one characteristic of
the
fluid, such as a characteristic of a chemical process of interest transpiring
in the
fluid. The output of electromagnetic radiation from the processing element can
be reflected electromagnetic radiation, transmitted electromagnetic radiation,
and/or dispersed electromagnetic radiation. Whether reflected, transmitted, or
dispersed, electromagnetic radiation is eventually analyzed by the detector
and
may be dictated by the structural parameters of the optical computing device
as
well as other considerations known to those skilled in the art. In addition,
emission and/or scattering of the substance, for example via fluorescence,
luminescence, Raman scattering, and/or Raleigh scattering, can also be
monitored by the optical computing devices.
[0034] As used herein, the term "optically interact" or variations thereof
refers to the reflection, transmission, scattering, diffraction, or absorption
of
electromagnetic radiation either on, through, or from one or more processing
elements (i.e., integrated computational elements). Accordingly, optically
interacted light refers to light that has been reflected, transmitted,
scattered,
diffracted, or absorbed by, emitted, or re-radiated, for example, using the
integrated computational elements, but may also apply to interaction with a
fluid
or an analyte thereof.
[0035] The exemplary systems and methods described herein will
include at least one optical computing device arranged along or in a flow path
in
order to monitor a fluid or an analyte thereof flowing or otherwise contained
within the flow path. Each optical computing device may include an
electromagnetic radiation source, at least one processing element (e.g.,
integrated computational element), and at least one detector arranged to
receive optically interacted light from the at least one processing element.
In
some embodiments, the exemplary optical computing devices may be
specifically configured for detecting, analyzing, and quantitatively measuring
a
particular characteristic of interest in the flow path. In at least one
embodiment,
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the characteristic may be related to a chemical process of interest (e.g., a
cement setting process) and the optical computing devices may be configured to
numerically determine the kinetics of reaction in near or real-time. In other
embodiments, the optical computing devices may be general purpose optical
devices, with post-acquisition processing (e.g., through computer means) being
used to specifically detect the characteristic of the fluid or an analyte
thereof.
[0036] In some embodiments, suitable structural components for the
exemplary optical computing devices are described in commonly owned U.S. Pat.
Nos. 6,198,531 entitled "Optical Computational System;" 6,529,276 entitled
"Optical Computational System;" 7,123,844 entitled "Optical Computational
System;" 7,834,999 entitled "Optical Analysis System and Optical Train;"
7,911,605 entitled "Multivariate Optical Elements for Optical Analysis
System;"
7,920,258 entitled "Optical Analysis System and Elements to Isolate Spectral
Region;" and 8,049,881 entitled "Optical Analysis System and Methods for
Operating Multivariate Optical Elements in a Normal Incidence Orientation;"
and
U.S. Pat. App. Serial Nos. 12/094,460 entitled "Methods of High-Speed
Monitoring Based on the Use of Multivariate Optical Elements;" 12/094,465
entitled "Optical Analysis System for Dynamic Real-Time Detection and
Measurement;" and 13/456,467 entitled "Imaging Systems for Optical
Computing Devices." As will be appreciated, variations of the structural
components of the optical computing devices described in the above-referenced
patents and patent applications may be suitable, without departing from the
scope of the disclosure, and therefore, should not be considered limiting to
the
various embodiments or uses disclosed herein.
[0037] The optical computing devices described in the foregoing patents
and patent applications combine the advantage of the power, precision, and
accuracy associated with laboratory spectrometers, while being extremely
rugged and suitable for field use. Furthermore, the optical computing devices
can perform calculations (analyses) in real-time or near real-time without the
need for time-consuming sample processing. In this regard, the optical
computing devices can be specifically configured to detect and analyze
particular
characteristics of interest. As a result, interfering signals are
discriminated from
those of interest by appropriate configuration of the optical computing
devices,
such that the optical computing devices provide a rapid response regarding the
characteristic of interest as based on the detected output. In some
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embodiments, the detected output can be converted into a voltage that is
distinctive of the magnitude of the characteristic of interest. The foregoing
advantages and others make the optical computing devices particularly well
suited for field and downhole use.
[0038] The optical computing devices can be configured to detect not
only the composition and concentrations of an analyte in a fluid, but they
also
can be configured to determine physical properties and other characteristics
of
the analyte and/or fluid as well, based on their analysis of the
electromagnetic
radiation received from the particular analyte and/or fluid. For example, the
optical computing devices can be configured to determine a characteristic of
interest, e.g., a concentration of a reagent or product, and correlate the
determined characteristic to the status of a cement setting process by using
suitable processing means. As will be appreciated, the optical computing
devices
may be configured to detect as many characteristics of interest as desired.
All
that is required to accomplish the monitoring of multiple characteristics is
the
incorporation of suitable processing and detection means within the optical
computing device for each characteristic of interest, whether pertaining to
the
fluid or an analyte thereof. In some embodiments, the cement setting status
can
be determined using a combination of characteristics of interest (e.g., a
linear,
non-linear, logarithmic, and/or exponential combinations). Accordingly, the
more
characteristics of interest that are detected and analyzed using the optical
computing devices, the more accurately the cement setting status can be
determined.
[0039] The optical computing devices described herein use
electromagnetic radiation to perform calculations, as opposed to the hardwired
circuits of conventional electronic processors. When electromagnetic radiation
interacts with a fluid or analyte thereof, unique physical and chemical
information about the material of interest may be encoded in the
electromagnetic radiation that is reflected from, transmitted through, or
radiated
therefrom. This information is often referred to as the spectral "fingerprint"
of
the material of interest. The optical computing devices described herein are
capable of extracting the information of the spectral fingerprint of multiple
characteristics of a material of interest (e.g., a cement slurry, a spacer
fluid, or
an analyte thereof), and converting that information into a detectable output
regarding the overall properties of the monitored material of interest. That
is,
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through suitable configurations of the optical computing devices,
electromagnetic radiation associated with characteristics of interest in a
fluid or
analyte thereof can be separated from electromagnetic radiation associated
with
all other components of the fluid in order to estimate the properties of the
monitored substance in real-time or near real-time.
[0040] The processing elements used in the exemplary optical
computing devices described herein may be characterized as integrated
computational elements (ICE). Each ICE is capable of distinguishing
electromagnetic radiation related to the characteristic of interest from
electromagnetic radiation related to other components of a fluid. Referring to
FIG. 1, illustrated is an exemplary ICE 100 suitable for use in the optical
computing devices used in the systems and methods described herein. As
illustrated, the ICE 100 may include a plurality of alternating layers 102 and
104, such as silicon (Si) and Si02 (quartz), respectively. In general, these
layers
102, 104 consist of materials whose index of refraction is high and low,
respectively. Other examples might include niobia and niobium, germanium and
germania, MgF, SiOx, and other high and low index materials known in the art.
The layers 102, 104 may be strategically deposited on an optical substrate
106.
In some embodiments, the optical substrate 106 is BK-7 optical glass. In other
embodiments, the optical substrate 106 may be another type of optical
substrate, such as quartz, sapphire, silicon, germanium, zinc selenide, zinc
sulfide, or various plastics such as polycarbonate, polymethylmethacrylate
(PMMA), polyvinylchloride (PVC), diamond, ceramics, combinations thereof, and
the like.
[0041] At the opposite end (e.g., opposite the optical substrate 106 in
FIG. 1), the ICE 100 may include a layer 108 that is generally exposed to the
environment of the device or installation. The number of layers 102, 104 and
the thickness of each layer 102, 104 are determined from the spectral
attributes acquired from a spectroscopic analysis of a characteristic of
interest
using a conventional spectroscopic instrument. The spectrum of interest of a
given characteristic of interest typically includes any number of different
wavelengths. It should be understood that the exemplary ICE 100 in FIG. 1
does not in fact represent any particular characteristic of interest, but is
provided for purposes of illustration only. Consequently, the number of layers
102, 104 and their relative thicknesses, as shown in FIG. 1, bear no
correlation
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to any particular characteristic of interest. Nor are the layers 102, 104 and
their
relative thicknesses necessarily drawn to scale, and therefore should not be
considered limiting of the present disclosure. Moreover, those skilled in the
art
will readily recognize that the materials that make up each layer 102, 104
(i.e.,
Si and Si02) may vary, depending on the application, cost of materials, and/or
applicability of the materials to the monitored substance.
[0042] In some embodiments, the material of each layer 102, 104 can
be doped or two or more materials can be combined in a manner to achieve the
desired optical characteristic. In addition to solids, the exemplary ICE 100
may
also contain liquids and/or gases, optionally in combination with solids, in
order
to produce a desired optical characteristic. In the case of gases and liquids,
the
ICE 100 can contain a corresponding vessel (not shown), which houses the
gases or liquids. Exemplary variations of the ICE 100 may also include
holographic optical elements, gratings, piezoelectric, light pipe, digital
light pipe
(DLP), variable optical attenuators, and/or acousto-optic elements, for
example,
that can create transmission, reflection, and/or absorptive properties of
interest.
[0043] The multiple layers 102, 104 exhibit different refractive indices.
By properly selecting the materials of the layers 102, 104 and their relative
thickness and spacing, the ICE 100 may be configured to selectively
pass/reflect/refract predetermined fractions of electromagnetic radiation at
different wavelengths. Each wavelength is given a predetermined weighting or
loading factor. The thickness and spacing of the layers 102, 104 may be
determined using a variety of approximation methods from the spectrograph of
the characteristic of interest. These methods may include inverse Fourier
transform (IFT) of the optical transmission spectrum and structuring the ICE
100 as the physical representation of the IFT. The approximations convert the
IFT into a structure based on known materials with constant refractive
indices.
Further information regarding the structures and design of exemplary
integrated
computational elements (also referred to as multivariate optical elements) is
provided in Applied Optics, Vol. 35, pp. 5484-5492 (1996) and Vol. 129, pp.
2876-2893.
[0044] The weightings that the layers 102, 104 of the ICE 100 apply
at each wavelength are set to the regression weightings described with respect
to a known equation, or data, or spectral signature. Briefly, the ICE 100 may
be
configured to perform the dot product of the input light beam into the ICE 100
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and a desired loaded regression vector represented by each layer 102, 104 for
each wavelength. As a result, the output light intensity of the ICE 100 is
related
to the characteristic of interest. Further details regarding how the exemplary
ICE
100 is able to distinguish and process electromagnetic radiation related to
the
characteristic of interest are described in U.S. Pat. Nos. 6,198,531 entitled
"Optical Computational System;" 6,529,276 entitled "Optical Computational
System;" and 7,920,258 entitled "Optical Analysis System and Elements to
Isolate Spectral Region."
[0045] Referring now to FIG. 2, illustrated is a block diagram that non-
mechanistically illustrates how an optical computing device 200 is able to
distinguish electromagnetic radiation related to a characteristic of interest
from
other electromagnetic radiation. As shown in FIG. 2, after being illuminated
with
incident electromagnetic radiation, a fluid 202 having a characteristic of
interest
produces an output of electromagnetic radiation (e.g., sample-interacted
light),
some of which is electromagnetic radiation 204 corresponding to the
characteristic of interest and some of which is background electromagnetic
radiation 206 corresponding to other components or characteristics of the
fluid
202. In some embodiments, the fluid 202 may include one or more
characteristics of interest that may correspond to the one or more analytes
(e.g., reagents, products, or other chemical components).
[0046] Although not specifically shown, one or more spectral elements
may be employed in the device 200 in order to restrict the optical wavelengths
and/or bandwidths of the system and thereby eliminate unwanted
electromagnetic radiation existing in wavelength regions that have no
importance. Such spectral elements can be located anywhere along the optical
train, but are typically employed directly after a light source, which
provides the
initial electromagnetic radiation. Various configurations and applications of
spectral elements in optical computing devices may be found in commonly
owned U.S. Pat. Nos. 6,198,531 entitled "Optical Computational System;"
6,529,276 entitled "Optical Computational System;" 7,123,844 entitled "Optical
Computational System;" 7,834,999 "Optical Analysis System and Optical Train;"
7,911,605 entitled "Multivariate Optical Elements for Optical Analysis
System;"
7,920,258 entitled "Optical Analysis System and Elements to Isolate Spectral
Region;" and 8,049,881 entitled "Optical Analysis System and Methods for
Operating Multivariate Optical Elements in a Normal Incidence Orientation;"
and
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U.S. Pat. App. Serial Nos. 12/094,460 entitled "Methods of High-Speed
Monitoring Based on the Use of Multivariate Optical Elements;" 12/094,465
entitled "Optical Analysis System for Dynamic Real-Time Detection and
Measurement;" and 13/456,467 entitled "Imaging Systems for Optical
Computing Devices."
[0047] The beams of electromagnetic radiation 204, 206 impinge upon
the optical computing device 200, which contains an exemplary ICE 208
therein. In the illustrated embodiment, the ICE 208 may be configured to
produce optically interacted light, for example, transmitted optically
interacted
light 210 and reflected optically interacted light 214. In operation, the ICE
208
may be configured to distinguish the electromagnetic radiation 204 from the
background electromagnetic radiation 206.
[0048] The transmitted optically interacted light 210, which may be
related to a characteristic of interest in the fluid 202, may be conveyed to a
detector 212 for analysis and quantification. In some embodiments, the
detector
212 is configured to produce an output signal in the form of a voltage that
corresponds to the particular characteristic of interest of the fluid 202. In
at
least one embodiment, the signal produced by the detector 212 and the
concentration of the characteristic of interest may be directly proportional.
In
other embodiments, the relationship may be a polynomial function, an
exponential function, and/or a logarithmic function. The reflected optically
interacted light 214, which may be related to characteristics of other
components of the fluid 202, can be directed away from detector 212. In
alternative configurations, the ICE 208 may be configured such that the
reflected optically interacted light 214 can be related to the particular
characteristic of interest, and the transmitted optically interacted light 210
can
be related to other components or characteristics of the fluid 202.
[0049] In some embodiments, a second detector 216 can be present
and arranged to detect the reflected optically interacted light 214. In other
embodiments, the second detector 216 may be arranged to detect the
electromagnetic radiation 204, 206 derived from the fluid 202 or
electromagnetic radiation directed toward or before the fluid 202. Without
limitation, the second detector 216 may be used to detect radiating deviations
stemming from an electromagnetic radiation source (not shown), which provides
the electromagnetic radiation (i.e., light) to the device 200. For example,
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radiating deviations can include such things as, but not limited to, intensity
fluctuations in the electromagnetic radiation, interferent fluctuations (e.g.,
dust
or other interferents passing in front of the electromagnetic radiation
source),
coatings on windows included with the optical computing device 200,
combinations thereof, or the like. In some embodiments, a beam splitter (not
shown) can be employed to split the electromagnetic radiation 204, 206, and
the transmitted or reflected electromagnetic radiation can then be directed to
two or more ICE 208. That is, in such embodiments, the ICE 208 does not
function as a type of beam splitter, as depicted in FIG. 2, and the
transmitted or
reflected electromagnetic radiation simply passes through the ICE 208, being
computationally processed therein, before travelling to the detector 212.
[0050] The characteristic(s) of interest being analyzed using the optical
computing device 200 can be further processed and/or analyzed
computationally to provide additional characterization information about the
fluid
202 or an analyte thereof. In some embodiments, the identification and
concentration of each analyte of interest in the fluid 202 can be used to
predict
certain physical characteristics of the fluid 202. For example, the bulk
characteristics of the fluid 202 can be estimated by using a combination of
the
properties conferred to the fluid 202 by each analyte.
[0051] In some embodiments, the concentration or magnitude of the
characteristic of interest determined using the optical computing device 200
can
be fed into an algorithm operating under computer control. The algorithm may
be configured to make predictions on how the characteristics of the fluid 202
would change if the concentrations of the characteristic of interest are
changed
relative to one another. In some embodiments, the algorithm can produce an
output that is readable by an operator who can manually take appropriate
action, if needed, based upon the reported output. In other embodiments,
however, the algorithm can take proactive process control by, for example,
automatically adjusting the flow of a fluid being introduced into a flow path
or by
halting the introduction of the fluid in response to an out of range
condition, for
example, if premature setting is detected.
[0052] In some embodiments, the characteristics of interest determined
using the optical computing devices 200 can be associated with a timestamp. A
timestamp may be useful in reviewing and analyzing the history of the
characteristic of interest, which may be of added value in building a library
of
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cement setting processes. In some embodiments, the characteristics of
interest,
optionally timestarnped, can be fed into an algorithm operating under computer
control. The algorithm may be configured to make predictions on the status of
the cement setting process and/or any operational parameters that need to be
changed as described further below. In some embodiments, the algorithm can
produce an output that is readable by an operator who can manually take
appropriate action, like initiation of a remedial operation, if needed, based
upon
the output.
[0053] The algorithm can be part of an artificial neural network
configured to use the concentration of each characteristic of interest in
order to
evaluate the overall characteristic(s) of the fluid 202 and predict how to
modify
the fluid 202 in order to alter its properties in a desired way. Illustrative
but
non-limiting artificial neural networks are described in commonly owned U.S.
Pat. App. No. 11/986,763 entitled "Determining Stimulation Design Parameters
Using Artificial Neural Networks Optimized with a Genetic Algorithm." It is to
be
recognized that an artificial neural network can be trained using samples of
predetermined characteristics of interest, such as known reagents and products
resulting from chemical processes involving such reagents, having known
concentrations, compositions, and/or properties, and thereby generating a
virtual library. As the virtual library available to the artificial neural
network
becomes larger, the neural network can become more capable of accurately
predicting the characteristic of interest corresponding to a fluid or analyte
thereof. Furthermore, with sufficient training, the artificial neural network
can
more accurately predict the characteristics of the fluid, even in the presence
of
unknown analytes.
[0054] It is recognized that the various embodiments herein directed to
computer control and artificial neural networks, including various blocks,
modules, elements, components, methods, and algorithms, can be implemented
using computer hardware, software, combinations thereof, and the like. To
illustrate this interchangeability of hardware and software, various
illustrative
blocks, modules, elements, components, methods and algorithms have been
described generally in terms of their functionality. Whether such
functionality is
implemented as hardware or software will depend upon the particular
application
and any imposed design constraints. For at least this reason, it is to be
recognized that one of ordinary skill in the art can implement the described
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functionality in a variety of ways for a particular application. Further,
various
components and blocks can be arranged in a different order or partitioned
differently, for example, without departing from the scope of the embodiments
expressly described.
[0055] Computer hardware used to implement the various illustrative
blocks, modules, elements, components, methods, and algorithms described
herein can include a processor configured to execute one or more sequences of
instructions, programming stances, or code stored on a non-transitory,
computer-readable medium. The processor can be, for example, a general
purpose microprocessor, a microcontroller, a digital signal processor, an
application specific integrated circuit, a field programmable gate array, a
programmable logic device, a controller, a state machine, a gated logic,
discrete
hardware components, an artificial neural network, or any like suitable entity
that can perform calculations or other manipulations of data. In some
embodiments, computer hardware can further include elements such as, for
example, a memory (e.g., random access memory (RAM), flash memory, read
only memory (ROM), programmable read only memory (PROM), erasable read
only memory (EPROM)), registers, hard disks, removable disks, CD-ROMS,
DVDs, or any other like suitable storage device or medium.
[0056] Executable sequences described herein can be implemented with
one or more sequences of code contained in a memory. In some embodiments,
such code can be read into the memory from another machine-readable
medium. Execution of the sequences of instructions contained in the memory
can cause a processor to perform the process steps described herein. One or
more processors in a multi-processing arrangement can also be employed to
execute instruction sequences in the memory. In addition, hard-wired circuitry
can be used in place of or in combination with software instructions to
implement various embodiments described herein. Thus, the present
embodiments are not limited to any specific combination of hardware and/or
software.
[0057] As used herein, a machine-readable medium will refer to any
medium that directly or indirectly provides instructions to a processor for
execution. A machine-readable medium can take on many forms including, for
example, non-volatile media, volatile media, and transmission media. Non-
volatile media can include, for example, optical and magnetic disks. Volatile
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media can include, for example, dynamic memory. Transmission media can
include, for example, coaxial cables, wire, fiber optics, and wires that form
a
bus. Common forms of machine-readable media can include, for example, floppy
disks, flexible disks, hard disks, magnetic tapes, other like magnetic media,
CD-
ROMs, DVDs, other like optical media, punch cards, paper tapes and like
physical
media with patterned holes, RAM, ROM, PROM, EPROM and flash EPROM.
[0058] In some embodiments, the data collected using the optical
computing devices can be archived along with data associated with operational
parameters being logged at a job site. Evaluation of job performance can then
be assessed and improved for future operations or such information can be used
to design subsequent operations. In addition, the data and information can be
communicated (wired or wirelessly) to a remote location by a communication
system (e.g., satellite communication or wide area network communication) for
further analysis. The communication system can also allow remote monitoring
and operation of a chemical reaction process to take place. Automated control
with a long-range communication system can further facilitate the performance
of remote job operations. In particular, an artificial neural network can be
used
in some embodiments to facilitate the performance of remote job operations.
That is, remote job operations can be conducted automatically in some
embodiments. In other embodiments, however, remote job operations can occur
under direct operator control, where the operator is not at the job site
(e.g., via
wireless technology).
[0059] Referring now to FIG. 3A, illustrated is an exemplary system
300 for monitoring a fluid, such as a chemical reaction process that may occur
within the fluid and/or to ascertain the location of the fluid, according to
one or
more embodiments. In the illustrated embodiment, the fluid may be contained
or otherwise flowing within an exemplary flow path provided by the casing 304
and/or an annulus 364 defined between the wellbore 360 and the casing 304.
In at least one embodiment, the fluid present therein may be flowing in the
general direction indicated by the arrows A (e.g., in a reverse cementing
operation). As will be appreciated, however, in other embodiments the flow
path
may be any other type of flow path, as generally described or otherwise
defined
herein. For example, the flow path may be a storage or reaction vessel and the
fluid may not necessarily be flowing while being monitored.
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[0060] With continued reference to FIG. 3A, the system 300 may
include at least one optical computing device 306, which may be similar in
some
respects to the optical computing device 200 of FIG. 2, and therefore may be
best understood with reference thereto. The optical computing device 306 may
be housed within a casing or housing (not shown) configured to substantially
protect the internal components of the device 306 from damage or
contamination from the external environment. The housing may operate to
mechanically couple the device 306 to the casing 304 with, for example,
mechanical fasteners, brazing or welding techniques, adhesives, magnets,
combinations thereof and the like. In operation, the housing may be designed
to
withstand the pressures that may be experienced within or without the flow
path
and thereby provide a fluid tight seal against external contamination.
[0061] As described in greater detail below, the optical computing
device 306 may be useful in determining a particular characteristic of the
fluid
within the flow path, such as determining a concentration of an analyte (e.g.,
reagent or product) present within the fluid. In the event the fluid is a
cement
slurry, knowing the presence and/or concentration of analytes found in the
cement slurry may help determine, in some embodiments, (1) the location of the
cement slurry (e.g., by monitoring a spacer fluid and/or the cement slurry)
and/or (2) the status of the cement setting processes of the cement slurry.
Knowing any one of the foregoing may provide guidance to an operator as to
parameters of the current operation or subsequent operations. For example,
knowing the location of the cement slurry may be useful in determining
appropriate pumping speeds of the cement slurry. In other instances, knowing
the precise location of the cement slurry as opposed to a generalized
calculation
of its location (i.e., the location of the cement slurry calculated using,
inter alia,
the amount of cement slurry introduced, the flow rate, and the estimated
volume to be filled) may be used to determine if the amount of cement slurry
used in a particular cementing operation should be changed so as to prevent an
unnecessary second cementing operation if too little is used. An accurate
determination of the location of the cement slurry may also forego the need
for
remedial operations (e.g., drill-out operations) in the event too much cement
slurry is used. In yet other instances, comparing the location of the cement
slurry to its calculated location may be useful in determining if damage has
occurred to a wellbore, for example, where cement may be leaking or lost into,
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and perhaps damaging, the adjacent subterranean formation. In other instances,
comparing the actual location of the cement slurry to the calculated location
may
avert losing fluids to the formations by identifying presence of potential
thief
zones (i.e., natural or man-made high permeability zones such as fractures,
vugular zones, or voids) into which large volumes (e.g., <10 to >500 barrels
of
fluid per hour) of a fluid can be lost. Further, in some reverse cementing
operation embodiments, knowing the time of arrival of a cement slurry at the
bottom of the casing may be advantageous for preventing entry of excessive
amount cement slurry into the pipe that will require a remedial operation,
e.g., a
1.0 drillout.
[0062] The device 306 is illustrated in FIG. 3A as an integral part of
the casing 304. One skilled in the art would understand that the device 306
may be coupled to the casing 304 so as to be disposed on a surface of the
casing 304, partially integrated into a wall of the casing 304, extend
outwardly
beyond a surface of the casing 304, be flush with a surface of the casing 304,
and any hybrid thereof. In some embodiments, the device 306 may be coupled
to the casing 304 so as to monitor a fluid in the annulus 364 and/or a fluid
in
the casing conduit 362.
[0063] Referring now to FIG. 3B, with continued reference to FIG. 3A,
the device 306 may include an electromagnetic radiation source 308 configured
to emit or otherwise generate electromagnetic radiation 310. The
electromagnetic radiation source 308 may be any device capable of emitting or
generating electromagnetic radiation, as defined herein. For example, the
electromagnetic radiation source 308 may be a light bulb, a light emitting
device
(LED), a laser, a blackbody, a photonic crystal, an X-Ray source, combinations
thereof, or the like. In some embodiments, a lens 312 may be configured to
collect or otherwise receive the electromagnetic radiation 310 and direct a
beam
314 of electromagnetic radiation 310 toward the fluid. The lens 312 may be
any type of optical device configured to transmit or otherwise convey the
electromagnetic radiation 310 as desired. For example, the lens 312 may be a
normal lens, a Fresnel lens, a diffractive optical element, a holographic
graphical
element, a mirror (e.g., a focusing mirror), a type of collimator, or any
other
electromagnetic radiation transmitting device known to those skilled in art.
In
other embodiments, the lens 312 may be omitted from the device 306 and the
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electromagnetic radiation 310 may instead be conveyed toward the fluid
directly
from the electromagnetic radiation source 308.
[0064] In one or more embodiments, the device 306 may also include a
sampling window 316 arranged adjacent to or otherwise in contact with the
fluid
(e.g., the fluid contained in the flow paths described above in FIG. 3A) for
detection purposes. The sampling window 316 may be made from a variety of
transparent, rigid or semi-rigid materials that are configured to allow
transmission of the electromagnetic radiation 310 therethrough. For example,
the sampling window 316 may be made of, but is not limited to, glasses,
plastics, semi-conductors, crystalline materials, polycrystalline materials,
hot or
cold-pressed powders, combinations thereof, or the like. In order to remove
ghosting or other imaging issues resulting from reflectance on the sampling
window 316, the system 300 may employ one or more internal reflectance
elements (IRE), such as those described in co-owned U.S. Pat. No. 7,697,141
entitled "In Situ Optical Computational Fluid Analysis System and Method,"
and/or one or more imaging systems, such as those described in co-owned U.S.
Pat. App. Ser. No. 13/456,467 entitled "Imaging Systems for Optical Computing
Devices."
[0065] After passing through the sampling window 316, the
electromagnetic radiation 31.0 impinges upon and optically interacts with the
fluid, including any analytes thereof. As a result, optically interacted
radiation
318 is generated by and reflected from the fluid. Those skilled in the art,
however, will readily recognize that alternative variations of the device 306
may
allow the optically interacted radiation 318 to be generated by being
transmitted, scattered, diffracted, absorbed, emitted, or re-radiated by
and/or
from the fluid, or one or more reagents/products present within the fluid,
without departing from the scope of the disclosure.
[0066] The optically interacted radiation 318 generated by the
interaction with the fluid may be directed to or otherwise received by an ICE
320 arranged within the device 306. The ICE 320 may be a spectral component
substantially similar to the ICE 100 described above with reference to FIG. 1.
Accordingly, in operation the ICE 320 may be configured to receive the
optically
interacted radiation 318 and produce modified electromagnetic radiation 322
corresponding to a particular characteristic of interest. In particular, the
modified
electromagnetic radiation 322 is electromagnetic radiation that has optically
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interacted with the ICE 320, whereby an approximate mimicking of the
regression vector corresponding to the characteristic of interest is obtained.
In
some embodiments, the characteristic of interest corresponds to the fluid. In
other embodiments, the characteristic of interest corresponds to a particular
analyte (e.g., a reagent or a product) found in the fluid.
[0067] It should be noted that, while FIG. 3B depicts the ICE 320 as
receiving reflected electromagnetic radiation from the fluid, the ICE 320 may
be
arranged at any point along the optical train of the device 306, without
departing from the scope of the disclosure. For example, in one or more
embodiments, the ICE 320 (as shown in dashed) may be arranged within the
optical train prior to the sampling window 316 and equally obtain
substantially
the same results. In other embodiments, the sampling window 316 may serve a
dual purpose as both a transmission window and the ICE 320 (i.e., a spectral
component). In yet other embodiments, the ICE 320 may generate the modified
electromagnetic radiation 322 through reflection, instead of transmission
therethroug h.
[0068] Moreover, while only one ICE 320 is shown in the device 306,
embodiments are contemplated herein which include the use of at least two ICE
components in the device 306 configured to cooperatively determine the
characteristic of interest in the fluid. For example, two or more ICE may be
arranged in series or parallel within the device 306 and configured to receive
the
optically interacted radiation 318 and thereby enhance sensitivities and
detector
limits of the device 306. In other embodiments, two or more ICE may be
arranged on a movable assembly, such as a rotating disc or an oscillating
linear
array, which moves such that the individual ICE components are able to be
exposed to or otherwise optically interact with electromagnetic radiation for
a
distinct brief period of time. The two or more ICE components in any of these
embodiments may be configured to be either associated or disassociated with
the characteristic of interest in the fluid. In other embodiments, the two or
more
ICE may be configured to be positively or negatively correlated with the
characteristic of interest. These optional embodiments employing two or more
ICE components are further described in co-pending U.S. Pat. App. Ser. Nos.
13/456,264 entitled "Methods and Devices for Optically Determining a
Characteristic of a Substance," 13/456,405 entitled "Methods and Devices for
Optically Determining A Characteristic of a Substance," 13/456,302 entitled
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"Methods and Devices for Optically Determining A Characteristic of a
Substance,"
and 13/456,327 entitled "Methods and Devices for Optically Determining A
Characteristic of a Substance."
[0069] In some embodiments, it may be desirable to monitor more than
one characteristic of interest at a time using the device 306. In such
embodiments, various configurations for multiple ICE components can be used,
where each ICE component is configured to detect a particular and/or distinct
characteristic of interest corresponding, for example, to the fluid, a
reagent, or a
product resulting from a chemical reaction in the fluid. In some embodiments,
the characteristic of interest can be analyzed sequentially using multiple ICE
components that are provided a single beam of electromagnetic radiation being
reflected from or transmitted through the fluid. In some embodiments, as
briefly
mentioned above, multiple ICE components can be arranged on a rotating disc,
where the individual ICE components are only exposed to the beam of
electromagnetic radiation for a short time. Advantages of this approach can
include the ability to analyze multiple characteristics of interest within the
fluid
using a single optical computing device and the opportunity to assay
additional
characteristics simply by adding additional ICE components to the rotating
disc
corresponding to those additional characteristics.
[0070] In other embodiments, multiple optical computing devices can
be placed at a single location along the flow path, where each optical
computing
device contains a unique ICE that is configured to detect a particular
characteristic of interest. In such embodiments, a beam splitter can divert a
portion of the electromagnetic radiation being reflected by, emitted from, or
transmitted through the fluid and into each optical computing device. Each
optical computing device, in turn, can be coupled to a corresponding detector
or
detector array that is configured to detect and analyze an output of
electromagnetic radiation from the respective optical computing device.
Parallel
configurations of optical computing devices can be particularly beneficial for
applications that require low power inputs and/or no moving parts.
[0071] Those skilled in the art will appreciate that any of the foregoing
configurations can further be used in combination with a series configuration
in
any of the present embodiments. For example, two optical computing devices
having a rotating disc with a plurality of ICE components arranged thereon can
be placed in series for performing an analysis at a single location along the
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length of the flow path. Likewise, multiple detection stations, each
containing
optical computing devices in parallel, can be placed in series for performing
a
similar analysis.
[0072] The modified electromagnetic radiation 322 generated by the
ICE 320 may subsequently be conveyed to a detector 324 for quantification of
the signal. The detector 324 may be any device capable of detecting
electromagnetic radiation, and may be generally characterized as an optical
transducer. In some embodiments, the detector 324 may be, but is not limited
to, a thermal detector such as a thermopile or photoacoustic detector, a
semiconductor detector, a piezo-electric detector, a charge coupled device
(CCD)
detector, a video or array detector, a split detector, a photon detector (such
as a
photomultiplier tube), photodiodes, combinations thereof, or the like, or
other
detectors known to those skilled in the art.
[0073] In some embodiments, the detector 324 may be configured to
produce an output signal 326 in real-time or near real-time in the form of a
voltage (or current) that corresponds to the particular characteristic of
interest.
The voltage returned by the detector 324 is essentially the dot product of the
optical interaction of the optically interacted radiation 318 with the
respective
ICE 320 as a function of the concentration of the characteristic of interest.
As
such, the output signal 326 produced by the detector 324 and the concentration
of the characteristic of interest may be related, for example, directly
proportional. In other embodiments, however, the relationship may correspond
to a polynomial function, an exponential function, a logarithmic function,
and/or
a combination thereof.
[0074] In some embodiments, the device 306 may include a second
detector 328, which may be similar to the first detector 324 in that it may be
any device capable of detecting electromagnetic radiation. Similar to the
second
detector 216 of FIG. 2, the second detector 328 of FIG. 3 may be used to
detect radiating deviations stemming from the electromagnetic radiation source
308. Undesirable radiating deviations can occur in the intensity of the
electromagnetic radiation 310 due to a wide variety of reasons and potentially
cause various negative effects on the output of the device 306. These negative
effects can be particularly detrimental for measurements taken over a period
of
time. In some embodiments, radiating deviations can occur as a result of a
build-up of film or material on the sampling window 316 which has the effect
of
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reducing the amount and quality of light ultimately reaching the first
detector
324. Without proper compensation, such radiating deviations could result in
false readings and the output signal 326 would no longer be primarily or
accurately related to the characteristic of interest.
[0075] To compensate for these types of undesirable effects, the
second detector 328 may be configured to generate a compensating signal 330
generally indicative of the radiating deviations of the electromagnetic
radiation
source 308, and thereby normalize the output signal 326 generated by the first
detector 324. As illustrated, the second detector 328 may be configured to
receive a portion of the optically interacted radiation 318 via a beamsplitter
332
in order to detect the radiating deviations. In other embodiments, however,
the
second detector 328 may be arranged to receive electromagnetic radiation from
any portion of the optical train in the device 306 in order to detect the
radiating
deviations, without departing from the scope of the disclosure.
[0076] In some applications, the output signal 326 and the
compensating signal 330 may be conveyed to or otherwise received by a signal
processor 334 communicably coupled to both the detectors 324, 328. The
signal processor 334 may be a computer including a non-transitory machine-
readable medium, and may be configured to computationally combine the
compensating signal 330 with the output signal 326 in order to normalize the
output signal 326 in view of any radiating deviations detected by the second
detector 328. In some embodiments, computationally combining the output and
compensating signals 326,330 may entail computing a ratio of the two signals
326,330. For example, the concentration or magnitude of each characteristic of
interest determined using the optical computing device 306 can be fed into an
algorithm run by the signal processor 334. The algorithm may be configured to
make predictions on how the characteristics of the fluid change if the
concentration of the measured characteristic of interest changes.
[0077] In real-time or near real-time, the signal processor 334 may be
configured to provide a resulting output signal 336 corresponding to the
characteristic of interest, such as a concentration of a reagent or resulting
product present in the fluid. In some embodiments, as briefly discussed above,
the resulting output signal 336 may be readable by an operator who can
consider the results and make proper adjustments to the flow path or take
appropriate action, if needed, based upon the magnitude of the measured
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characteristic of interest. In some embodiments, the resulting output signal
336
may be conveyed, either wired or wirelessly, to the user for consideration.
[0078] Referring now to FIG. 4, illustrated is an exemplary system 400
for monitoring a fluid according to one or more embodiments. In the
illustrated
embodiment, the system 400 includes a plurality of optical computing devices
406,406',406" coupled to a casing 404 in series along the length of the casing
404. Each optical computing device 406,406',406" may be similar to the
optical computing device 306 of FIGS. 3A and 3B, and therefore will not be
described again in detail. Such a plurality of devices 406,406',406" may be
advantageous to monitor the location and status of fluids during a wellbore
operation. For example, illustrated in FIG. 4 is a traditional cementing
operation
for completing a wellbore 460. As illustrated by arrows A, a fluid (i.e.,
cement
slurry) may flow through the casing conduit 462 change directions at the end
of
a casing 404 so as to flow through the annulus 464 defined between the
wellbore 460 and the casing 404.
[0079] As illustrated in FIG. 4, a first device 406" may be disposed at
the end of the casing 404 where the fluid enters the annulus 464. Arranging
the
first device 406" at such a location may be advantageous in determining when
the fluid has reached the end of the casing 404. Second and third devices 406
and 406' may be useful in monitoring the location of the fluid as it moves
through the annulus 464 and/or the casing conduit 462. In some instances,
calculating the actual speed with which the fluid moves through the annulus
464
and/or the casing conduit 462 with the devices 406,406',406" may be
compared to the calculated speed the fluid should be moving. A slow actual
speed may be an indicator that the fluid is being lost into portions of the
subterranean formation. Knowing fluid loss is occurring at some point in the
wellbore 460 may allow for the operator to change the pumping speeds to
minimize fluid loss, or otherwise add additional fluid to the operation to
ensure
complete and proper placement of a cement slurry. A determination of fluid
loss
in the wellbore 460 may also provide the operator with an opportunity to
proactively alter the properties and/or composition of the fluid being pumped
into the wellbore, such as by adding fluid loss control agents, to minimize
fluid
loss.
[0080] As with the embodiments discussed above, the devices
406,406',406" may independently include multiple ICE components and be
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configured to measure one or more characteristics of the fluid in the annulus
464 and the casing conduit 462. Those skilled in the art will readily
appreciate
the various and numerous applications that the systems 300 and 400, and
alternative configurations thereof, may be suitably used with.
[0081] Some subterranean operation embodiments of the present
invention may involve introducing a fluid or series of fluids (i.e., two or
more
fluids in series) into a wellbore or an annulus defined therein; optically
interacting an electromagnetic radiation source with the fluid and at least
one
integrated computational element, thereby generating optically interacting
light;
receiving with at least one detector the optically interacted light; and
generating
with the at least one detector an output signal corresponding to a
characteristic
of the fluid.
[0082] In some embodiments, the fluid introduced into the wellbore
may include a spacer fluid and/or a cement slurry. In some embodiments, the
fluid may be a series of fluids, e.g., in order, a flush, a first spacer
fluid, a
cement slurry, and a second spacer or a displacement fluid.
[0083] In some embodiments, a cement slurry may comprise an
aqueous fluid, cement particles, and optionally further comprise fillers
and/or
additives like set-time modifiers and other analytes listed herein. In some
embodiments, a cement slurry may be foamed and comprise an aqueous fluid,
cement particles, a gas, and a foaming agent and optionally further comprise
fillers and/or additives like set-time modifiers and other analytes listed
above.
[0084] In some embodiments, a spacer fluid may comprise an aqueous
fluid, a weighting agent, surfactants, and optionally further comprise
additives
like salts and other analytes listed above.
[0085] In some embodiments, a fluid of interest may comprise a tracer
additive having the primary function of being detected by a device comprising
the integrated computational element.
[0086] Some subterranean operation embodiments of the present
invention may involve introducing a fluid or series of fluids into a wellbore
or
annulus therein; optically interacting light from an electromagnetic radiation
source with the fluid and at least one integrated computational element,
thereby
generating optically interacting light; receiving with at least one detector
the
optically interacted light; generating with the at least one detector an
output
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signal corresponding to a characteristic of the fluid; and correlating the
output
signal with a location within the wellbore or annulus therein.
[0087] Some subterranean operation embodiments of the present
invention may involve introducing a fluid or series of fluids into a wellbore
or
annulus therein; optically interacting an electromagnetic radiation source
with
the fluid and at least one integrated computational element, thereby
generating
optically interacting light; receiving with at least one detector the
optically
interacted light; generating with the at least one detector an output signal
corresponding to a characteristic of the fluid; and changing a parameter of
the
wellbore operation in response to the output signal. Parameters that are
changed may include, but are not limited to, the pumping speed, the amount of
fluid introduced, the composition of the fluid introduced, termination of the
pumping operation, switching to pumping a displacement fluid or remedial pill
(i.e., a small volume of a remedial fluid pumped to repair a damaged zone),
and
the like, and any combination thereof.
[0088] Some subterranean operation embodiments of the present
invention may involve introducing a fluid or series of fluids into a wellbore
or
annulus therein; optically interacting an electromagnetic radiation source
with
the fluid and at least one integrated computational element, thereby
generating
optically interacting light; receiving with at least one detector the
optically
interacted light; generating with the at least one detector an output signal
corresponding to a characteristic of the fluid; and correlating the output
signal to
a cement setting process, examples of which are provided above. In some
embodiments, knowing the status of a cement setting process may be used in,
inter alia, determining the timing of a subsequent subterranean operation.
Performing an operation before the cement has set may cause damage to the
cement and necessitate costly remedial operations. In situ monitoring of
cement
setting processes may eliminate the need for costly and time-consuming
wireline
logging operations. Further, in situ monitoring may further reduce the time
between the cementing operation and a subsequent operation, in that, the
cement may set more quickly than expected and in situ monitoring would
provide real-time or near real-time data to that effect.
[0089] In some embodiments, the output signal may be correlated to
both the status of the cement setting process and the location. For example,
when flowing a cement it may be useful to know if the cement has begun to
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prematurely set and where the premature setting is occurring. Premature
setting
may be caused by the cement slurry encountering an analyte in the wellbore
that increases the setting speed and/or encountering higher temperatures.
Premature setting may cause formation damage and require remedial
operations. Knowing setting has begun during pumping may allow for changing
the operational parameters to minimize or eliminate the need for remedial
operations.
[0090] It should also be noted that the various drawings provided
herein are not necessarily drawn to scale nor are they, strictly speaking,
depicted as optically correct as understood by those skilled in optics.
Instead,
the drawings are merely illustrative in nature and used generally herein in
order
to supplement understanding of the systems and methods provided herein.
Indeed, while the drawings may not be optically accurate, the conceptual
interpretations depicted therein accurately reflect the exemplary nature of
the
various embodiments disclosed.
[0091] Some embodiments disclosed herein include
[0092] A. A method comprising: containing a cement slurry within a
flow path, the cement slurry having a chemical reaction occurring therein; and
optically interacting the cement slurry with an integrated computational
element,
thereby generating an output signal corresponding to a characteristic of the
chemical reaction.
[0093] B. A method comprising: flowing a series of fluids through a flow
path, the series of fluids comprising a spacer fluid followed by a cement
slurry;
and optically interacting at least one of the series of fluids with an
integrated
computational element, thereby generating an output signal corresponding to a
characteristic of the at least one of the series of fluids.
[0094] Each of embodiments A and B may have one or more of the
following additional elements in any combination:
[0095] Element 1: wherein the flow path comprises at least one
selected from the group consisting of a wellbore, a casing, and an annulus
between a wellbore and a casing.
[0096] Element 2:
wherein optically interacting further comprises
reflecting an electromagnetic radiation off of the cement slurry.
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[0097] Element 3: further comprising: receiving the output signal with
a signal processor communicably coupled to the at least one detector; and
determining the characteristic of the chemical reaction with the signal
processor.
[0098] Element 4: further comprising: correlating the output signal
with a location of the integrated computational element within the flow path.
[0099] Element 5: wherein generating the output signal corresponding
to the characteristic of the chemical reaction further comprises determining a
concentration of one or more analytes in the cement slurry.
[0100] Element 6: wherein the characteristic of the chemical reaction
comprises at least one selected from the group consisting of a chemical
composition, an impurity content, a pH level, a temperature, a viscosity, a
density, an ionic strength, a total dissolved solids measurement, a salt
content
measurement, a porosity, an opacity measurement, a particle size distribution,
any derivative thereof, and any combination thereof.
[0101] Element 7: further comprising: correlating the output signal with
a location of the at least one of the series of fluids within the flow path.
[0102] Element 8: further comprising: changing an operational
parameter based on the location of the at least one of the series of fluids
within
the flow path.
[0103] Element 9: further comprising: correlating the output signal
with a chemical reaction occurring in the cement slurry.
[0104] Element 9: further comprising: performing a remedial operation
based on the chemical reaction occurring in the cement slurry.
[0105] Element 10:
further comprising: changing an operational
parameter based on the chemical reaction occurring in the cement slurry.
[0106] Element 11:
wherein generating the output signal further
comprises determining a concentration of one or more analytes in the at least
one of the series of fluids.
[0107] Element 12: wherein the one or more analytes comprise at
least one selected from the group consisting of water, salt, a mineral,
wollastonite, metakaolin, pumice, a cement, Portland cement, gypsum cement, a
calcium phosphate cement, a high alumina content cement, a silica cement, a
high alkalinity cement, a filler, fly ash, fume silica, hydrated lime,
pozzolanic
material, sand, barite, calcium carbonate, ground marble, iron oxide,
manganese
oxide, glass bead, crushed glass, a crushed drill cutting, ground vehicle
tire,
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crushed rock, ground asphalt, crushed concrete, crushed cement, ilmenite,
hematite, silica flour, fume silica, fly ash, an elastomer, a polymer,
diatomaceous earth, a highly swellable clay mineral, nitrogen, air, a fiber,
natural rubber, acrylate butadiene rubber, polyacrylate rubber, isoprene
rubber,
chloroprene rubber, butyl rubber, brominated butyl rubber, chlorinated butyl
rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer
rubber, sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin
ethylene oxide copolymer, ethylene propylene rubber, ethylene propylene diene
terpolymer rubber, ethylene vinyl acetate copolymer, flourosilicone rubber,
silicone rubber, poly-2,2,1-bicycloheptene, alkylstyrene, crosslinked
substituted
vinyl acrylate copolymer, nitrile rubber, hydrogenated nitrile rubber, fluoro
rubber, perfluoro rubber, tetraflouroethylene/propylene, starch polyacrylate
acid
graft copolymer, polyvinyl alcohol cyclic acid anhydride graft copolymer,
isobutylene maleic anhydride, acrylic acid type polymer, vinylacetate-acrylate
copolymer, polyethylene oxide polymer, carboxymethyl cellulose polymer,
starch-polyacrylonitrile graft copolymer, polymethacrylate, polyacrylamide,
and
non-soluble acrylic polymer), hydrocarbon, an acid, an acid-generating
compound, a base, a base-generating compound, a biocide, a surfactant, a scale
inhibitor, a corrosion inhibitor, a gelling agent, a crosslinking agent, an
anti-
sludging agent, a foaming agent, a defoaming agent, an antifoam agent, a
emulsifying agent, a de-emulsifying agent, a iron control agent, a proppants
or
other particulate, a gravel, particulate diverter, a salt, a cement slurry
loss
control additive, a gas migration control additive, a gas, air, nitrogen,
carbon
dioxide, hydrogen sulfide, argon, helium, a hydrocarbon gas, methane, ethane,
butane, catalyst, a clay control agent, a chelating agent, a corrosion
inhibitor, a
dispersant, a flocculant, a scavenger, an H2S scavenger, a CO2 scavenger, an
02 scavenger, a lubricant, a breaker, a delayed release breaker, a friction
reducer, a bridging agent, a viscosifier, a weighting agent, a solubilizer, a
rheology control agent, a viscosity modifier, a pH control agent, a buffer, a
hydrate inhibitor, a relative permeability modifier, a diverting agent, a
consolidating agent, a fibrous material, a bactericide, a tracer, a probe, a
nanoparticle, a paraffin wax, an asphaltene, a foam, sand, and any combination
thereof
[0108] Other embodiments disclosed herein include:
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[0109] C. A system, comprising: a flow path containing a cement
slurry; and at least two optical computing devices arranged in the flow path
for
monitoring the cement slurry, each of the at least two optical computing
devices
independently having at least one integrated computational element configured
to optically interact with the cement slurry and thereby generate optically
interacted light, and at least one detector arranged to receive the optically
interacted light and generate an output signal corresponding to a
characteristic
of the cement slurry.
[0110] Embodiment C may have one or more of the following additional
elements in any combination:
[0111] Element 1: The embodiment C wherein the characteristic of the
cement slurry is a concentration of one or more analytes in the cement slurry.
[0112] Element 2: The embodiment C wherein the characteristic of the
cement slurry corresponds to a reaction occurring within a cement slurry.
[0113] Element 3: The embodiment C wherein the characteristic of the
cement slurry comprises at least one selected from the group consisting of
chemical composition, impurity content, pH, viscosity, density, ionic
strength,
total dissolved solids, salt content, porosity, opacity, bacteria content,
particle
size distribution, color, temperature, hydration level, and an analyte
oxidation
state.
[0114] Element 4: The embodiment C further comprising: a signal
processor communicably coupled to the at least two optical computing devices
for receiving the output signal therefrom, the signal processor being
configured
to determine a progress of a chemical reaction occurring within the cement
slurry.
[0115] Therefore, 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, combined, or modified and all such variations are considered within
the
scope and spirit of the present invention. The invention illustratively
disclosed
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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 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.
