FIELD OF THE DISCLOSURE

The present disclosure relates generally to optical sensors and, more specifically, to an Integrated Computational Element ("ICE") core based optical device that uses moveable assemblies to simultaneously detect the analytic and compensation signals to thereby determine sample characteristics.

BACKGROUND

In recent years, optical computing techniques have been developed for applications in the oil and gas industry in the form of optical sensors in downhole or surface equipment to evaluate a variety of fluid properties. In general, an optical computing device is a device configured to receive an input of electromagnetic radiation from a sample and produce an output of electromagnetic radiation from a processing element, also referred to as an optical element, wherein the output reflects the measured intensity of the electromagnetic radiation. The optical computing device may be, for example, an ICE. One type of an ICE is an optical thin film optical interference device, also known as a multivariate optical element ("MOE").

Fundamentally, optical computing devices utilize optical elements to perform calculations, as opposed to the hardwired circuits of conventional electronic processors. When light from a light source interacts with a substance, unique physical and chemical information about the substance is encoded in the electromagnetic radiation that is reflected from, transmitted through, or radiated from the sample. Thus, the optical computing device, through use of the ICE and one or more detectors, is capable of extracting the information of one or multiple characteristics/analytes within a substance and converting that information into a detectable output signal reflecting the overall properties of a sample. Such characteristics may include, for example, the presence of certain elements, compositions, fluid phases, etc. existing within the substance.

The characteristic or analyte of interest is directly related to the intensity of the light transmitted both through the sample and through the ICE. This light is generally referred to as the analytic "A" Channel. One challenge in optical computing or ICE computing devices is that the light intensity in the A Channel may fluctuate. Such fluctuations might occur for a variety of reasons, including weakening of the bulb over time, in response to analyte concentration variations, or other spurious effects such as dust and dirt accumulation on the optical elements and windows. These spurious effects will cause the A Channel light intensity to fluctuate and, therefore, introduce variations in the accuracy of the optical device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a well system having optical computing devices deployed therein for sample characteristic detection according to certain illustrative embodiments of the present disclosure;

FIG. 2 is a block diagram of an optical computing device for sample characteristic detection employing a single moveable assembly design, according to certain illustrative embodiments of the present disclosure;

FIG. 3 is a block diagram of another optical computing device employing a dual moveable assembly design, according to certain illustrative embodiments of the present disclosure;

FIG. 4 illustrates a block diagram of yet another optical computing device employing a linear array as the moveable assembly, according to certain illustrative embodiments of the present disclosure; and

FIG. 5 is a moveable assembly according to certain alternative embodiments of the present disclosure.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments and related methodologies of the present disclosure are described below as they might be employed in an optical computing device and method to simultaneously detect the analytic and compensation signals to determine sample characteristics. In the interest of clarity, not all features of an actual implementation or methodology are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system- related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments and related methodologies of the disclosure will become apparent from consideration of the following description and drawings.

As described herein, one or more illustrative embodiments of the present disclosure are directed to an optical computing device that simultaneously detects the analytic and compensation signals to determine sample characteristics. As previously described, one of the challenges in optical computing is that the light intensity in the A Channel may fluctuate, thereby introducing errors in the accuracy of the measurements. Therefore, illustrative embodiments of the present disclosure normalize or ratio out the spurious effects using a second compensation "B" Channel. In a first generalized embodiment, the optical computing device includes an electromagnetic radiation source and a moveable assembly, such as, for example, a rotating carousel or linear array, having at least one optical element pair positioned thereon. The optical elements may be an ICE and/or a neutral density element. The optical elements may also be band pass filters, for example, or other elements designed to pass desired portions of the electromagnetic spectrum. One of the optical elements may form an analytic channel, while the other may form a compensation channel.

During operation, electromagnetic radiation optically interacts with the sample to form sample-interacted light, which is directed toward the optical elements on the moveable assembly. The optical elements are positioned on the moveable assembly such that the sample-interacted light optically interacts with both elements simultaneously, thereby providing compensation in parallel with the sample characteristic measurement (via the analytic channel).

In one or more generalized embodiments, the moveable assemblies may be two synchronized rotating carousels. Both carousels may include optical elements, whereby one carousel forms the analytic channel and the other forms the compensation channel. During operation, the carousels can be synchronously rotated such that the sample- interacted light simultaneously interacts with both optical elements, thereby providing compensation in parallel with the sample characteristic measurement (via the analytic channel).

Each of the above generalized embodiments may include a plurality of optical element pairs. In such embodiments, the moveable assembly may include a first and second row, whereby one of the rows forms the analytic channel, while the other row forms the compensation channel. As a result, multiple analytes may be detected in realtime while providing more accurate measurements of dynamic fluid samples.

The optical computing devices described herein may be utilized in a variety of environments. Such environments may include, for example, downhole well or completion applications. Other environments may include those as diverse as those associated with surface and undersea monitoring, satellite or drone surveillance, pipeline monitoring, or even sensors transiting a body cavity such as a digestive tract. Within those environments, the optical computing devices are utilized to detect/monitor various sample compounds or characteristics, in real time, within the environment.

Although the optical computing devices described herein may be utilized in a variety of environments, for illustrative purposes the following description will focus on downhole well applications. FIG. 1 illustrates a plurality of optical computing devices 22 positioned along a workstring 21 extending along a downhole well system 10 (also referred to herein as a downhole reservoir interrogation system) according to certain illustrative embodiments of the present disclosure. Workstring 21 may be, for example, a logging assembly, production string or drilling assembly. Well system 10 comprises a vertical wellbore 12 extending down into a hydrocarbon formation 14 (although not illustrated, wellbore 12 may also comprise one or more lateral sections). Wellbore equipment 20 is positioned atop vertical wellbore 12, as understood in the art. Wellbore equipment may be, for example, a blow out preventer, derrick, floating platform, etc. As understood in the art, after vertical wellbore 12 is formed, tubulars 16 (casing, for example) are extended therein to complete wellbore 12.

One or more optical computing devices 22 may be positioned along wellbore 12 at any desired location. In certain embodiments, optical computing devices 22 are positioned along the internal or external surfaces of downhole tool 18 (as shown in FIG. 1) which may be, for example, intervention equipment, surveying equipment, or completion equipment including valves, packers, screens, mandrels, gauge mandrels, in addition to casing or tubing tubulars/joints as referenced below. Alternatively, however, optical computing devices 22 may be permanently or removably attached to tubulars 16 and distributed throughout wellbore 12 in any area in which corrosion detection/monitoring or formation evaluation is desired. Optical computing devices 22 may be coupled to a remote power supply (located on the surface or a power generator positioned downhole along the wellbore, for example), while in other embodiments each optical computing device 22 comprises an on-board battery. Moreover, optical computing devices 22 are communicably coupled to a CPU station 24 via a communications link 26, such as, for example, a wireline, inductive coupling or other suitable communications link. Those ordinarily skilled in the art having the benefit of this disclosure will readily appreciate that the number and location of optical computing devices 22 may be manipulated as desired.

As will be described in more detail below, each optical computing device 22 comprises an ICE and neutral density ("ND") element pair (i.e., first and second optical elements) positioned on one or more moveable assemblies which both optically interact with a sample of interest (wellbore fluid, downhole tool component, tubular, formation, for example) to determine one or more sample characteristics. In certain illustrative embodiments, optical computing devices 22 may determine the presence and quantity of specific gases, fluids, components and properties relevant to hydrocarbon exploration and production such as, for example, CO ₂ , H ₂ S, methane (CI), ethane (C2) and propane (C3), saline water, dissolved ions (Ba, CI, Na, Fe, or Sr, for example) or various other characteristics (p.H., density and specific gravity, viscosity, total dissolved solids, sand content, etc.). Furthermore, the presence of formation characteristic data (viscosity, phase, formation chemical composition, etc.) may also be determined. In certain embodiments, a single optical computing device 22 may detect a single characteristic, while in others a single optical computing device 22 may determine multiple characteristics, as will be understood by those ordinarily skilled in the art having the benefit of this disclosure.

CPU station 24 comprises a signal processor (not shown), communications module (not shown) and other circuitry necessary to achieve the objectives of the present disclosure, as will be understood by those ordinarily skilled in the art having the benefit of this disclosure. In addition, it will also be recognized that the software instructions necessary to carry out the objectives of the present disclosure may be stored within storage located in CPU station 24 or loaded into that storage from a CD-ROM or other appropriate storage media via wired or wireless methods. Communications link 26 provides a medium of communication between CPU station 24 and optical computing devices 22. Communications link 26 may be a wired link, such as, for example, a wireline or fiber optic cable extending down into vertical wellbore 12. Alternatively, however, communications link 26 may be a wireless link, such as, for example, an electromagnetic device of suitable frequency, or other methods including acoustic communication and like devices. In certain illustrative embodiments, CPU station 24, via its signal processor, controls operation of each optical computing device 22. In addition to sensing operations, CPU station 24 may also control activation and deactivation of optical computing devices 22. Optical computing devices 22 each include a transmitter and receiver (transceiver, for example) (not shown) that allows bi-directional communication over communications link 26 in real-time. In certain illustrative embodiments, optical computing devices 22 will transmit all or a portion of the corrosion/formation or other sample characteristic data to CPU station 24 for further analysis. However, in other embodiments, such analysis is partially or completely handled by each optical computing device 22 and the resulting data is then transmitted to CPU station 24 for storage or subsequent analysis. In either embodiment, the processor handling the computations analyzes the characteristic data and, through utilization of Equation of State ("EOS") or other optical analysis techniques, derives the desired sample characteristic indicated by the transmitted data.

Still referring to the illustrative embodiment of FIG. 1 , optical computing devices 22 are positioned along workstring 21 at any desired location. In this example, optical computing devices 22 are positioned along the outer diameter of downhole tool 18. Optical computing devices 22 have a temperature and pressure resistant housing sufficient to withstand the harsh downhole environment. A variety of materials may be utilized for the housing, including, for example, stainless steels and their alloys, titanium and other high strength metals, and even carbon fiber composites and sapphire or diamond structures, as understood in the art. In certain embodiments, optical computing devices 22 are dome- shaped modules (akin to a vehicle dome light) which may be permanently or removably attached to a surface using a suitable method (welding, magnets, etc.). Module housing shapes may vary widely, provided they isolate components from the harsh down-hole environment while still allowing a unidirectional or bidirectional optical (or electromagnetic radiation) pathway from sensor to the sample of interest. Dimensions would be determined by the specific application and environmental conditions.

Alternatively, optical computing devices 22 may form part of downhole tool 18 (as shown in FIG. 1) along its inner or outer diameter. In other embodiments as will be described below, optical computing devices 22 may be coupled to downhole tool 18 using an extendable arm (adjustable stabilizer, casing scraper, downhole tractor, for example) in order to extend optical computing device 22 into close proximity with another surface (casing, tool body, formation, etc.) to thereby detect sample characteristics (e.g., formation evaluation). As previously described, optical computing devices 22 may also be permanently affixed to the inner diameter of tubular 16 by a welding or other suitable process. However, in yet another embodiment, optical computing devices 22 are removably affixed to the inner diameter of tubulars 16 using magnets or physical structures so that optical computing devices 22 may be periodically removed for service purposes or otherwise. Although illustrated in FIG 1 as deployed along a drilling and/or logging string, embodiments of the present disclosure may also be deployed along a wireline assembly.

FIG. 2 is a block diagram of an optical computing device 200, according to certain illustrative embodiments of the present disclosure. An electromagnetic radiation source 208 may be configured to emit or otherwise generate electromagnetic radiation 210. As understood in the art, electromagnetic radiation source 208 may be any device capable of emitting or generating electromagnetic radiation. For example, electromagnetic radiation source 208 may be a light bulb, light emitting device, laser, blackbody, photonic crystal, or X-Ray source, etc. In other embodiments, the source of electromagnetic radiation 210 may be ambient light present in the device.

Nevertheless, in one embodiment, electromagnetic radiation 210 may be configured to optically interact with the sample 205 (wellbore fluid flowing through wellbore 12 or a portion of the formation 14, for example) and generate sample-interacted light 212 directed to a beam splitter 202. Sample 205 may be any fluid (liquid or gas), solid substance or material such as, for example, downhole tool components, tubulars, rock formations, slurries, sands, muds, drill cuttings, concrete, other solid surfaces, etc. In other embodiments, however, sample 205 is a multiphase wellbore fluid (comprising oil, gas, water, solids, for example) consisting of a variety of fluid characteristics such as, for example, C1-C4 and higher hydrocarbons, groupings of such elements, and saline water.

Sample 205 may be provided to optical computing device 200 through a flow pipe or sample cell, for example, containing sample 205, whereby it is introduced to electromagnetic radiation 210. Alternatively, optical computing device 200 may utilize an optical configuration consisting of an internal reflectance element which analyzes the wellbore fluid as it flows thereby or which analyzes the surface of the sample (formation surface, for example). While FIG. 2 shows electromagnetic radiation 210 as passing through or incident upon the sample 205 to produce sample-interacted light 212 (i.e., transmission), it is also contemplated herein to reflect electromagnetic radiation 210 off of the sample 205 (i.e., reflectance mode), such as in the case of a sample 205 that is translucent, opaque, or solid, and equally generate the sample-interacted light 212.

After being illuminated with electromagnetic radiation 210, sample 205 containing an analyte of interest produces an output of electromagnetic radiation (sample-interacted light 212, for example). As previously described, sample-interacted light 212 also contains spectral information that reflects chemical and physical variations of the sample used to determine sample characteristics. Ultimately, CPU station 24 (or a processor on-board device 200) analyzes this spectral information to determine the sample characteristic. Although not specifically shown, one or more spectral elements may be employed in optical computing 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 the light source which provides the initial electromagnetic radiation.

Still referring to the illustrative embodiment of FIG. 2, beam splitter 202 is employed to split sample-interacted light 212 into a transmitted electromagnetic radiation 214 (i.e., first portion) and a reflected electromagnetic radiation 220 (i.e., second portion). Reflected electromagnetic radiation 220 is then directed to optical element 219 (e.g., mirror) which directs it to moveable assembly 203 (shown here as a rotating carousel), which includes at least one optical element 204 and a paired optical element 206 associated therewith. Note that moveable assembly 203 is only one example of a moveable assembly; in other illustrative embodiments, moveable assembly 203 may be linear array or other rotating disc, such as, for example, a chopper wheel, wherein optical elements 204 and 206 are radially disposed for rotation therewith. Transmitted electromagnetic radiation 214 is also directed to the moveable assembly 203. In this illustrative embodiment, optical element 204 is an ICE, while optical element 206 is an ND element, thereby forming an analytic and compensation channel, respectively. The ND element may be, for example, a neutral density filter which reduces or modifies the intensity of transmitted light across all wavelengths equally. The ND filter is typically selected to have a flat spectral response in the spectral region the ICE operates within.

As shown, moveable assembly 203 includes an outer row of optical elements 206 and an inner row for optical elements 204 with respect to a center axis A. As a result, there are a number of ICE-ND pairs P which are arranged beside one another in a column-like fashion. Although illustrated as having optical ICEs 204 in the inner row and ND element 206 in the outer row, the orientations may be reversed in alternate embodiments.

The moveable assembly 203 is configured to simultaneously align optical elements 204, 206 of each ICE-ND pair P with sample-interacted light 212 (i.e., transmitted electromagnetic radiation 214 and a reflected electromagnetic radiation 220). In certain embodiments, each ICE-ND pair P is designed to be either associated or disassociated with the same or a different characteristic of sample 205, thus forming a plurality of analytic and compensation channels. Although 8 optical element pairs P are shown, more or less optical element pairs may be employed along moveable assembly 203 as desired.

The moveable assembly 203 may be rotated about axis A at any desired frequency (e.g., 0.1 RPM to about 30,000 RPM). In operation, moveable assembly 203 may rotate such that the ICE and ND element of each pair P are simultaneously exposed to or otherwise optically interact with the sample-interacted light 212 for a distinct brief period of time. Thus, when an ICE used to measure an analyte of interest is aligned with its detector, the paired ND element is also aligned with its detector to provide the compensation signal. In this way, the ICE-ND element pair P are always sensing the same sample at the same time. Upon optically interacting with the transmitted electromagnetic radiation 214, optical element 204 (the ICE) is configured to generate optically interacted light 216A (also referred to herein as the "first optically- interacted light") which corresponds to a sample characteristic (thus forming analytic channel A), while optical element 206 (the paired ND element) is configured to generate optically interacted light 216B (also referred to herein as the "second optically- interacted light") (thus forming compensation channel B) upon interacting with reflected electromagnetic radiation 220. Detector 218 then receives optically interacted light 216A and thereby generates a first signal 222 (i.e., analytic signal), while detector 224 simultaneously receives optically interacted light 216B to generate second signal 226 (i.e., compensation signal). Accordingly, a signal processor (not shown) communicatively coupled to detectors 218,224 utilizes the output signals 222,226 to computationally determine the sample characteristics.

Detectors 218/224 may be any device capable of detecting electromagnetic radiation, and may be generally characterized as an optical transducer. For example, detector 218/224 may be, but is not limited to, a thermal detector such as a thermopile or photoacoustic detector, a semiconductor detector, a piezo-electric detector, charge coupled device detector, or array detector, split detector, photon detector (such as a photomultiplier tube), photodiodes, and /or combinations thereof, or the like, or other detectors known to those ordinarily skilled in the art. Detector 218/224 is further configured to produce an output signal 222 in the form of a voltage or current that corresponds to the particular characteristic of the sample 205. In at least one embodiment, the output signal, produced by computationally combining the output signals 222 and 226 from detector 218 and detector 224, and the characteristic concentration of the sample 205 may be directly proportional. In other embodiments, the relationship may be a polynomial function, an exponential function, and/or a logarithmic function.

As understood in the art, optically interacted light 216B (the compensation channel) may include a variety of electromagnetic radiation deviations such as, for example, intensity fluctuations in the electromagnetic radiation source 208, or light scattering fluctuations from suspended particles in the sample or optical path, combinations thereof, or the like. Thus, detector 224 measures these electromagnetic radiation deviations and is used to compensate signal 222 for these deviations.

As moveable assembly 203 continues to rotate, other ICE-ND pairs P are optically interacted with sample-interacted light 212. Here, as each ICE and ND element in pairs P simultaneously interacts with sample-interacted light 212 as previously described, time lapsed optically interacted lights (216Ai, 216Bi, 216A ₂ , 216B ₂ ...) are generated. Thus, in certain illustrative embodiments, detectors 218,224 may be configured to time multiplex beams (216Ai, 216Bi, 216A ₂ , 216B ₂ ...) between the individually-detected beams. For example, optical elements 204 and 206 may be configured to direct first beams 216Ai and 216Bi of a first ICE-ND pair P toward detectors 218 and 224, respectively, at a first time Tl, the beams 216A ₂ and 216B ₂ of a second ICE-ND pair P at a second time T2, and beams 2 I6A ₃ and 2I6B ₃ of a third ICE-ND pair P at a third time T3. Consequently, detectors 218,224 receive at least three distinct beams of optically- interacted light which may be computationally combined by a signal processor (not shown) coupled to the detectors in order to provide an output in the form of a voltage that corresponds to the characteristic of the sample, as previously described.

In certain alternate embodiments, the beams (216Ai, 216Bi, 216A ₂ , 216B ₂ ...) may be averaged over an appropriate time domain (for example, about 1 millisecond to about 5 minutes) to more accurately determine the characteristic of sample 205. As previously described, detectors 218,224 are positioned to detect the optically-interacted lights 216A,216B in order to produce output signals 222,226. In this embodiment, a signal processor (not shown) is communicably coupled to the detectors such that output signals 222,226 may be processed as desired to computationally determine the characteristic of sample 205.

Although not shown in FIG. 2, in certain illustrative embodiments, detectors 218,224 may be communicably coupled to a signal processor (not shown) on-board optical computing device 200 (or remote therefrom) such that compensation signal 226 indicative of electromagnetic radiating deviations may be provided or otherwise conveyed thereto. The signal processor may then be configured to computationally combine compensation signal 226 with analytic signal 222 to provide a more accurate determination of the characteristic of sample 205.

As previously described, optical element 204 may be an ICE, while optical element 206 may be an ND element, or vice versa. In an alternative embodiment, both optical elements 204 and 206 may be ICEs, thus forming an ICE-ICE pair whereby the ICEs form the analytic and compensation channels. In either embodiment, however, the ICE being used for the analytic channel is configured to be associated with a particular characteristic of sample 205 or may be designed to approximate or mimic the regression vector of the characteristic in a desired manner.

FIG. 3 illustrates a block diagram of yet another optical computing device 300 employing two independent moveable assemblies (e.g., rotating carousels), according to certain illustrative embodiments of the present disclosure. Optical computing device 300 is somewhat similar to optical computing device 200 described with reference to FIG. 2 and, therefore, may be best understood with reference thereto, where like numerals indicate like elements. However, acting as the moveable assembly in this example, optical computing device 300 includes a first moveable assembly 303A having one or more optical elements 304 (e.g., ICEs), and a second moveable assembly 303B having one or more optical elements 306 (e.g., NDs or ICEs) paired to the optical elements 304, as previously described. First and second moveable assemblies 303A,B are show in this example as rotating carousels, but may be any variety of moveable assemblies described herein. As illustrated, the moveable assemblies 303A and 303B may be characterized at least in one embodiment as a rotating disc, such as, for example, a chopper wheel, wherein optical elements 304 and 306 are radially disposed for rotation therewith. Each optical element 304,306 pair may be similar in construction to those as previously described herein, and are configured to be either associated or disassociated with a particular characteristic of the sample 205. For example, each optical element pair may be designed to determine a different sample characteristic. Although six optical element pairs are described, more or less optical pairs may be employed along moveable assemblies 303A and 303B as desired.

In certain illustrative embodiments, moveable assemblies 303A and 303B are each coupled to motors 325A and 325B, respectively. Although not shown, motors 325A and 325B may be coupled to processing circuitry, as previously described, in order to rotate assemblies 303A and 303B in a synchronized fashion so that corresponding pairs of optical elements 304 and 306 optically interact with sample-interacted light 212 (i.e., portions 214,220) at the same time. Alternatively, a single motor 325 with a mechanical linkage to assemblies 303A and 303B may be utilized. In certain embodiments, optical element 304 is an ICE, thus forming the analytic channel, while optical element 306 is an ND element, thus forming a compensation channel for its paired ICE. In other embodiments, the analytic and compensation channels may be formed using ICEs.

Nevertheless, upon optically interacting with the portions 214 and 220 of sample- interacted light 212, optical element pairs 304 and 306 are configured to generate optically interacted light 316A (analytic channel) and 316B (compensation channel), respectively. Detector 318 then receives optically interacted light 316A and detector 324 receives 316B to generate a first signal 222 and second signal 226, as previously described. Accordingly, a signal processor (not shown) communicatively coupled to detectors 218,224 utilizes the output signals to computationally determine the sample characteristics.

Furthermore, as described in relation to FIG. 2, during operation, motors 325A,B rotate assemblies 303A and 303B using a synchronous frequency. As a result, the ICE-ND pairs are simultaneously interacted with sample-interacted light 212. As shown in FIG. 3, the optical elements 304,306 are identified by i, ii, iii, iv, v, and vi, where like numerals identify the paired ICE-ND pairs (or ICE-ICE pairs in alternate embodiments). Thus, at a first time Tl, ICE-ND pairs i are simultaneously optically interacted with sample- interacted light 212, then at a second time T2, ICE-ND pairs ii are interacted, and so on. The resulting signals may also be multiplexed or otherwise analyzed to determine sample characteristics, as previously described. FIG. 4 illustrates a block diagram of yet another optical computing device 400 employing a linear array as the moveable assembly, according to certain illustrative embodiments of the present disclosure. Optical computing device 400 is somewhat similar to optical computing devices 200,300 described with reference to FIGS. 2 and 3, and therefore, may be best understood with reference thereto, where like numerals indicate like elements. However, optical computing device 400 includes a linear array 403 as the moveable assembly, having a first row of one or more optical elements 406 (e.g., ICEs), and a second row of corresponding optical elements 404 (e.g., NDs as illustrated, or ICEs) paired to the optical elements 406, as previously described. Each optical element 404,406 may be similar in construction to those as previously described herein, and are configured to be either associated or disassociated with a particular characteristic of the sample 205. Although eight optical element pairs P are illustrated, more or less optical pairs may be employed along linear array 403 as desired.

In certain illustrative embodiments, linear array includes a track 402 positioned thereon which mates with a gear 408 to move linear array along a single dimensional axis A. Although not shown, gear 408 is coupled to processing circuitry, as previously described, in order to rotate gear 408, and thus move linear array 403, at a desired speed to thereby sequence optical pairs P into interaction with sample-interacted light 212 (i.e., portions 214,220) at the same time. As shown, the various optical pairs P are located beside one another in a column-like fashion. In this embodiment, optical elements 404 are ICEs, thus forming the analytic channel, while optical elements 404 are ND elements, thus forming a compensation channel for its paired ICE. In other embodiments, the desired may be flipped and/or the analytic and compensation channels may be formed using ICEs.

Nevertheless, upon optically interacting with the portions 214 and 220 of sample- interacted light 212, optical element 406 and 404 pairs P are configured to generate optically interacted light 416A (analytic channel) and 416B (compensation channel), respectively. Detector 418 then receives optically interacted light 416A and detector 424 receives 416B to generate a first signal 222 and second signal 226, as previously described. As linear array 403 continues to move along axis A, each optical element pair P is sequenced until the last pair P is sequenced. Thereafter, gear 408 reverses linear array 403 back along axis A (similar to a type-writer) where the process may begin again. Accordingly, a signal processor (not shown) communicatively coupled to detectors 418,424 utilizes the sequenced output signals to computationally determine the sample characteristics.

FIG. 5 is a diagrammatical illustration of a rotating carousel 500 that may be used as a moveable assembly as described above, according to one or more embodiments of the present disclosure. Rotating carousel 500 is similar to moveable assembly 203 previously described with reference to FIG. 2, with some alterations. Instead of the column-like fashion of the optical pairs P, rotating carousel 500 includes a plurality of optical element 502,504 pairs P which are arranged side-by-side in an alternating row fashion. The other optical components (e.g., beam splitters, mirrors, etc.) may be arranged in any number of ways to achieve simultaneous interaction of the sample-interacted light with the analytic and compensation channels formed by the optical pairs P, as previously described. Moreover, although first optical element 502 is shown as the ICE, while second optical element 504 is shown as the ND element, the designed may be reversed and/or two ICEs may be utilized, as previously described.

The aforementioned optical computing devices are illustrative in nature, and may be subject to a variety of other optical configurations. Such optical configurations not only include the reflection, absorption or transmission methods described herein, but can also involve scattering (Raleigh & Raman, for example) as well as emission (fluorescence, X- ray excitation, etc., for example). In addition, the optical computing devices may comprise a parallel processing configuration whereby the sample-interacted light is split into multiple beams. The multiple beams may then simultaneously go through corresponding ICEs, whereby multiple characteristics and/or analytes of interest are simultaneously detected. The parallel processing configuration is particularly useful in those applications that require extremely low power or no moving parts.

Accordingly, the illustrative embodiments described herein eliminates the use of serial A and B measurements and provides more accurate measurements of dynamic fluid samples possible in systems that measure multiple ICE signals. Through the use of beam splitters and other optical elements, two optical paths (analytic and compensation channels) are created using two rows of optical elements on rotating carousels or a single row of optical elements on two synchronously rotating carousels. Each embodiment ensures that when an ICE is aligned with its detector, an ND element (or other ICE) is aligned with its detector concurrently. Such an arrangement results in the ICE and ND element always detecting the same sample at the same time. Accordingly, the described embodiments avoid the case where, due to a time interval between the A and B channel signal detection, a different sample is interrogated by each optical channel. In cases where the sample's properties are changing rapidly relative to the time between measurements of the A and B Channels, the two channels are not observing the same sample volume at the same time, which may result in reduced performance due to compensation variations. However, by simultaneously detecting both channels, such variations are avoided.

Embodiments described herein further relate to any one or more of the following paragraphs:

1. An optical computing device, comprising electromagnetic radiation that optically interacts with a sample to produce sample-interacted light; a moveable assembly, comprising: a first optical element that optically interacts with the sample-interacted light to produce first optically-interacted light which corresponds to a characteristic of the sample, thereby forming an analytic channel; and a second optical element that optically interacts with the sample-interacted light to produce second optically-interacted light utilized to compensate the analytic channel, thereby forming a compensation channel, wherein the first and second optical elements are positioned along the moveable assembly to simultaneously interact with the sample-interacted light; a first detector positioned to measure the first optically-interacted light and generate a first signal; and a second detector positioned to measure the second optically-interacted light and generate a second signal, wherein the first and second signals are utilized to determine the characteristics of the sample.

2. An optical computing device as defined in paragraph 1, further comprising: a beam splitter positioned to split the sample-interacted light into a first and second portion, the first portion being directed to the analytic channel; and an optical element positioned to direct the second portion toward the compensation channel.

3. An optical computing device as defined in paragraphs 1 or 2, wherein the first optical element is an Integrated Computational Element ("ICE"); and the second optical element is a neutral density element.

4. An optical computing device as defined in any of paragraphs 1-3, wherein the first and second optical elements are Integrated Computational Elements ("ICEs"). 5. An optical computing device as defined in any of paragraphs 1-4, wherein the moveable assembly comprises a plurality of analytic channels; and a plurality of compensation channels which correspond to the analytic channels.

6. An optical computing device as defined in any of paragraphs 1-5, wherein the moveable assembly is a carousel rotatably disposed about a center axis; the analytic channels are positioned along an outer row of the carousel in relation to the center axis; the compensation channels are positioned along an inner row of the carousel in relation to the center axis; and corresponding analytic and compensation channels are positioned beside each other in a column- fashion, thus forming an optical pair.

7. An optical computing device as defined in any of paragraphs 1-6, wherein: the moveable assembly is a linear array; the analytic channels are positioned along a first row of the linear array; the compensation channels are positioned along a second row of the linear array; and corresponding analytic and compensation channels are positioned beside each other in a column-fashion, thus forming an optical pair, wherein the linear array is moveable in a single dimension to sequence the optical pairs to interact with the sample-interacted light.

8. An optical computing device as defined in any of paragraphs 1-7, wherein the moveable assembly is a carousel; and the analytic and compensation channels are positioned in an alternating row-like fashion along the carousel such that corresponding analytic and compensation channels are positioned beside each other, thus forming an optical pair.

9. An optical computing device as defined in any of paragraphs 1-8, wherein: the moveable assembly is a carousel rotatably disposed about a center axis; the compensation channels are positioned along an outer row of the carousel in relation to the center axis; the analytic channels are positioned along an inner row of the carousel in relation to the center axis; and corresponding analytic and compensation channels are positioned beside each other in a column-fashion, thus forming an optical pair.

10. An optical computing device as defined in any of paragraphs 1-9, wherein the moveable assembly comprises: a first rotating carousel comprising the first optical element; and a second rotating carousel comprising the second optical element.

1 1. An optical computing device as defined in any of paragraphs 1-9, further comprising at least one motor coupled to the first and second rotating carousels in order to synchronously rotate the first and second rotating carousels. 12. An optical computing device as defined in any of paragraphs 1-11, further comprising a beam splitter positioned to split the sample-interacted light into a first and second portion, the first portion being directed to the analytic channel; and an optical element positioned to direct the second portion toward the compensation channel.

13. An optical computing device as defined in any of paragraphs 1-12, wherein the first rotating carousel further comprises a plurality of analytic channels; and the second rotating carousel further comprises a plurality of compensation channels which correspond to the analytic channels.

14. An optical computing device as defined in any one of paragraphs 1-13, further comprising an electromagnetic radiation source that generates the electromagnetic radiation.

15. An optical computing device as defined in any one of paragraphs 1-14, further comprising a signal processor communicably coupled to the first and second detector to computationally determine the characteristics of the sample.

16. An optical computing device as defined in any one of paragraphs 1-13, wherein the optical computing device comprises part of a downhole reservoir interrogation system.

17. An optical computing method, comprising optically interacting electromagnetic radiation with a sample to produce sample-interacted light; actuating a moveable assembly comprising a first and second optical element; optically interacting the sample-interacted light with the first optical element to produce first optically-interacted light which corresponds to a characteristic of the sample, thereby forming an analytic channel; optically interacting the sample-interacted light with the second optical element to produce second optically-interacted light utilized to compensate the analytic channel, thereby forming a compensation channel, wherein the sample-interacted light is simultaneously optically interacted with the first and second optical elements; generating a first signal that corresponds to the analytic channel; generating a second signal that corresponds to the compensation channel; and determining the characteristics of the sample using the first and second signals.

18. An optical computing method as defined in paragraph 17, wherein optically interacting the sample-interacted light with the first and second optical elements comprises: optically interacting the sample- interacted light with a beam splitter; splitting the sample-interacted light into a first and second portion; directing the first portion to the analytic channel; and directing the second portion toward the compensation channel.

19. An optical computing method as defined in paragraphs 17 and 18, wherein: optically interacting the sample-interacted light with the first optical element comprises optically interacting the sample-interacted light with an Integrated Computational Element ("ICE"); and optically interacting the sample-interacted light with the second optical element comprises optically interacting the sample-interacted light with a neutral density element.

20. An optical computing method as defined in any of paragraphs 17-19, wherein optically interacting the sample-interacted light with the first and second optical elements comprises optically interacting the sample-interacted light with Integrated Computational Elements ("ICEs").

21. An optical computing method as defined in any of paragraphs 17-20, wherein the moveable assembly further comprises: a plurality of analytic channels; and a plurality of compensation channels which correspond to the analytic channels, thus forming optical pairs.

22. An optical computing method as defined in any of paragraphs 17-21, wherein: the moveable assembly is a rotating carousel; and actuating the moveable assembly comprises rotating the carousel.

23. An optical computing method as defined in any of paragraphs 17-22, wherein: the moveable assembly is a linear array; and actuating the moveable assembly comprises moving the linear array along a single dimension, thereby sequencing the optical pairs to interact with the sample-interacted light.

24. An optical computing method as defined in any of paragraphs 17-23, further comprising utilizing the optical computing device as part of a downhole reservoir interrogation system.

25. An optical computing method as defined in any of paragraphs 17-24, wherein the moveable assembly comprises: a first carousel comprising a plurality of first optical elements; and a second carousel comprising a plurality of second optical elements which correspond to the first optical elements, thus forming optical pairs; and

actuating the moveable assembly comprises rotating the first and second carousels. 26. An optical computing method as defined in any of paragraphs 17-25, wherein the first and second carousels are synchronously rotated such that the optical pairs interact with the sample-interacted light in sequence.

27. An optical computing method as defined in any of paragraphs 17-26, wherein optically interacting the sample-interacted light with the first and second optical elements comprises optically interacting the sample-interacted light with a beam splitter; splitting the sample-interacted light into a first and second portion; directing the first portion to the analytic channel; and directing the second portion toward the compensation channel.

28. An optical computing method as defined in any of paragraphs 17-27, wherein: optically interacting the sample-interacted light with the first optical element comprises optically interacting the sample-interacted light with an Integrated Computational Element ("ICE"); and optically interacting the sample-interacted light with the second optical element comprises optically interacting the sample-interacted light with a neutral density element.

29. An optical computing method as defined in any of paragraphs 17-28, wherein optically interacting the sample-interacted light with the first and second optical elements comprises optically interacting the sample-interacted light with Integrated Computational Elements ("ICEs").

30. An optical computing method as defined in any of paragraphs 17-29, further comprising utilizing the optical computing device as part of a downhole reservoir interrogation system.

Although various embodiments and methodologies have been shown and described, this disclosure is not limited to such embodiments and methodologies, and will be understood to include all modifications and variations as would be apparent to one ordinarily skilled in the art. Therefore, it should be understood that the embodiments are not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of this disclosure as defined by the appended claims.