Patent Publication Number: US-11661845-B2

Title: Attenuated total internal reflection optical sensor for obtaining downhole fluid properties

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Patent Application No. 62/846,548 filed May 10, 2019 titled “SYSTEMS AND METHODS FOR OBTAINING DOWNHOLE FLUID PROPERTIES,” the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates to downhole measurements. More particularly, the present disclosure relates to obtaining a number of properties of the fluid inside a wellbore. 
     2. Description of Related Art 
     During oil and gas operations, it is often difficult to determine fluid properties in a downhole well due to inaccessibility, contamination of fluids, mixing of fluids, and the like. As a result, typical operations deploy multiple tools that may be specialized to determine a single fluid property, such as density. These tools are often fragile, and as a result, may not be utilized in multiple operations. Furthermore, installing multiple tools along a drill or wireline string increases costs of the operation and also may lead to slower drilling and or wireline logging operations because some tools are individually tripped into and out of the well. In additional, current techniques are incapable of performing true multi-phase fluid metering. Absorption or transmission spectroscopy is a commonly used optical analysis technique. The change in transmitted intensity can be measured through a variety of optical techniques. Constituents of a sample absorb light of respective wavelengths/frequencies. The amount of light absorbed by the sample at different wavelengths/frequencies depends on the presence and concentration of each constituent. Therefore, the absorption spectrum of the sample, or the frequency distribution of the absorbed light, can be used to identify the composition of the sample. Transmission absorption spectroscopy requires samples that are substantially optically translucent or transparent in the range of frequencies being studied. Therefore, conventional absorption spectroscopy may be difficult for analyzing dark or opaque samples or for highly scattering fluids that contain suspended particles such as sand or which contain small bubbles of one immiscible phase within another such as emulsions. 
     SUMMARY 
     Applicants recognized the problems noted above herein and conceived and developed embodiments of systems and methods, according to the present disclosure, for a multi-modal sensing and identification of fluid properties. By measuring multiple properties, applicants can distinguish all three phases, gas, liquid, and oil rather than just distinguishing liquid versus gas as is presently done. 
     In an embodiment, a downhole fluid analysis system includes an optical sensor comprising, which includes a light source configured to emit light comprising a plurality of wavelengths, a light detector, and an optical tip through which at least a portion of the light travels and returns to the detector, wherein the incident angle of the light causes total internal reflection within the optical tip. The system further includes a piezoelectric helm resonator that generates a resonance response in response to an applied current, and an electromagnetic spectroscopy sensor positioned symmetrically with respect to the piezoelectric helm resonator in at least one direction. The light may be reflected in the optical tip at one or more reflection points, and each reflection point may generate an evanescent wave in a medium surrounding the optical tip. The light may be internally reflected in the optical tip at a plurality of reflection points. The light may cause fluorescence in a medium surrounding the optical tip, which indicatives the presence of oil in the medium. The light emitted by the light source includes at least a first wavelength and a second wavelength. Attenuation of the first wavelength indicates presence of a first fluid type adjacent the optical tip and attenuation of the second wavelength indicates presence of a second fluid type adjacent the optical tip. The first wavelength is attenuated by the presence of oil and the second wavelength is attenuated by the presence of water. The light detector may be a spectrally resolved detector and detects intensity of different wavelength in the received light. The optical sensor may be positioned symmetrically with respect to the piezoelectric helm resonator. 
     In another embodiment, a downhole fluid analysis device includes an optical sensor which includes a first light source that emits light of a first wavelength, a second light source that emits light of a second wavelength, a beam combiner positioned to combine the light from the first light source and light from the second light source into a light beam, an optical tip positioned to receive the light beam, in which an angle of incidence of the light beam creates internal reflection of the light beam within the optical tip, and a light detection system positioned to receive returned light from the optical tip, the light detector resolving wavelengths present the returned light, and the intensity of the wavelengths. The first light source may emit a visible light and the second light source may emit an infrared light, and the light beam includes the visible light and the infrared light. The light detection system may include a visible light detector and an infrared light detector. The light detection system may include a spectrally resolved light detector. The light is reflected in the optical tip at one or more reflection points, and each reflection point generates an evanescent wave in a medium surrounding the optical tip. The light beam is internally reflected in the optical tip at a plurality of reflection points. The light detection system may detect attenuation of the first wavelength and the second wavelengths based on the returned light, in which attenuation of the first wavelength indicates presence of a first fluid type adjacent the optical tip and attenuation of the second wavelength indicates presence of a second fluid type adjacent the optical tip. Specifically, attenuation of the first wavelength may be attenuated by the presence of oil and attenuation of the second wavelength may be attenuated by the presence of water. 
     In another embodiment, a method of obtaining fluid properties in a well includes positioning a fluid sensor in a wellbore, in which the fluid sensor includes co-located piezoelectric helm resonator, optical sensor, and electromagnetic spectroscopy sensor. The method further includes applying electrical energy to the piezoelectric helm resonator to excite the piezoelectric helm resonator, receiving a signal from the piezoelectric helm resonator, determining one or more of density, viscosity, or sound speed of a region of fluid in the wellbore based at least in part the first signal from the piezoelectric helm resonator, and receiving an electromagnetic spectroscopy signal from the spectroscopy sensor. The method also includes emitting a light into an optical tip of the optical sensor, directing the light through a plurality of internal reflections in the optical tip before exiting the optical tip as returned light, receiving the returned light from the optical tip at a light detection system, and analyzing the spectral content of the returned light to determine components of the fluid. The light may be reflected in the optical tip at one or more reflection points, and wherein each reflection point generates an evanescent wave in a medium surrounding the optical tip. The method may also include determining a concentration of oil in the fluid based on the intensity of the first wavelength in the returned light, and determining a concentration of water in the fluid based on the intensity of the second wavelength in the returned light. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing aspects, features, and advantages of the present disclosure will be further appreciated when considered with reference to the following description of embodiments and accompanying drawings. In describing the embodiments of the disclosure illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose. 
         FIG.  1    is a schematic side view of an embodiment of a wireline system, in accordance with embodiments of the present disclosure. 
         FIG.  2    illustrates a perspective view of a fluid analysis tool in an expanded position, in accordance with example embodiments. 
         FIG.  3 A  illustrates the fluid analysis tool in the retracted position, in accordance with example embodiments. 
         FIG.  3 B  illustrates the fluid analysis tool in a first expanded position, in accordance with example embodiments. 
         FIG.  3 C  illustrates the fluid analysis tool in a second expanded position, in accordance with example embodiments. 
         FIG.  4    is a graph illustrating the deployment angles of the arms, the fluid sensors, and the flow spinners with respect to the casing inner diameter, in accordance with example embodiments. 
         FIG.  5    illustrates a perspective view of a downhole fluid analysis device, in accordance with example embodiments. 
         FIG.  6    illustrates a perspective view of the piezoelectric helm resonator of the downhole fluid analysis device, in accordance with example embodiments. 
         FIG.  7    illustrates an example circuit that can be used with embodiments of the present disclosure. 
         FIG.  8    illustrates a cross-sectional diagram view of the sensor of  FIG.  5   , in accordance with example embodiments. 
         FIG.  9    illustrates an example waveform associated with operation of the circuit of  FIG.  7   , in accordance with example embodiments. 
         FIG.  10    illustrates another example embodiment of a circuit that can be used with embodiments of the present disclosure. 
         FIG.  11    illustrates a waveform for operation of the circuit of  FIG.  10   , in accordance with example embodiments. 
         FIG.  12    illustrates light of multiple wavelengths traveling from a light source, through an optical tip, and to a detector, in accordance with example embodiments of the present disclosure. 
         FIG.  13    illustrates the reflection and attenuation of light through a tip of an optical sensor, in accordance with example embodiments of the present disclosure. 
         FIG.  14    illustrates an optical sensor with a bi-conical shape, in accordance with example embodiments of the present disclosure. 
         FIG.  15    is a diagram illustrating a bi-conical tip for an optical sensor, in accordance with example embodiments of the present disclosure. 
         FIG.  16    illustrates a plurality of example configurations of bi-conical optical tips, in accordance with example embodiments. 
         FIG.  17    is a system diagram illustrating an optical sensor, in accordance with example embodiments of the present disclosure. 
         FIG.  18    is a flow chart of an embodiment of a method for collecting and analyzing data utilizing the downhole fluid analysis device, in accordance with example embodiments. 
         FIG.  19    is a block diagram of an embodiment of a machine learning system that may be utilized with embodiment of the present disclosure, in accordance with example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The foregoing aspects, features, and advantages of the present disclosure will be further appreciated when considered with reference to the following description of embodiments and accompanying drawings. In describing the embodiments of the disclosure illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose. 
     When introducing elements of various embodiments of the present disclosure, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one embodiment”, “an embodiment”, “certain embodiments”, or “other embodiments” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, reference to terms such as “above”, “below”, “upper”, “lower”, “side”, “front”, “back”, or other terms regarding orientation or direction are made with reference to the illustrated embodiments and are not intended to be limiting or exclude other orientations or directions. 
     Embodiments of the present disclosure provide a piezoelectric helm resonator sensor array having simultaneous and mathematically congruent fluid density, viscosity, and sound speed measurements as well as integrated electromagnetic and optical spectroscopy characterization. Acoustic measurements are important in determining composition and chemical properties of unknown multi-phase fluids for applications in a variety of fields. Current devices and methods, such as those for measuring either fluid density or fluid sound speed rely on an a priori knowledge of the mass density of the continuous and dispersed phases of the flow, and are primarily for surface separation systems. However, existing approaches are not applicable to in situ downhole applications since the mass densities of the components of the flow are not generally known and are only estimable from surface “dead oil” properties that do not account for effects such as downhole pressure, temperature, and gas-saturation. Fluid optical properties and characteristics can be derived downhole from some of the following optical measurement techniques: reflectance, emittance, transmittance, absorbance, fluorescence, optical spectroscopy, refractive index dependent optical measurements, and others techniques known in the optical instrumentation art. 
     Embodiments of the present disclosure provide techniques (e.g., devices, systems, tools, methods) that allow multi-phase fluid properties (e.g., volume fractions, gas-oil-ratio, live-oil density, live-oil sound speed, and live-oil compressibility) to be determined from the direction measureable composite fluid acoustic properties of sound speed, bulk modulus and acoustic impedance. In order to make these correlations the measurements for sound speed, acoustic impedance and bulk modulus of the composite fluid flow must be obtained in a specific congruent manner. That is, from a single measurement domain [M-domain] with a sensing field of interaction that is simultaneous and congruent relative to all the acoustic measurements and all the continuous/dispersed particles. 
     Many factors present difficulty to the development of sensor technologies capable of these types of acoustic compositional measurements. Most important of these is the necessity for simultaneous and congruent measurements with respect to each other, thus providing a true measure of the bulk composite fluid density and sound speed that have correlations with compositional and chemical properties of the bulk fluid from the same volumetric sample within the sample zone measured. Existing approaches utilize two separate measurements of two non-identical fluid domains, for example M1-domain and M2-domain, to obtain measurements for fluid sound speed c1 in M1-domain and fluid mass density p2 in M2-domain. By measuring mass density and sound speed one can compute bulk modulus (inverse compressibility) because it equals the product of the fluid&#39;s mass density with the square of its sound speed. High compressibility is an indicator of high gas-oil ratio. 
     In order to examine the correlations that may exist between the various compositional properties of liquid-liquid flows and the bulk fluid acoustic properties of the mixtures, an ideal acoustic impedance sensor that can measure simultaneously and congruently fluid density and sound speed properties is needed. Further, it is tacitly required that the sensor measurement attained provide delineated bulk fluid properties estimates of mass density and sound speed that can be discriminated directly from the measurement without any a priori knowledge of or assumption with regard to elemental properties of the bulk composite fluid. Embodiments of the present disclosure provide a piezoelectric helm resonator sensor array having simultaneous and mathematically congruent fluid density, viscosity, and sound speed measurements as well as integrated electromagnetic and optical spectroscopy characterization. 
       FIG.  1    is a schematic elevation view of an embodiment of a wellbore system  10  that includes a work string  12  shown conveyed in a wellbore  14  formed in a formation  16  from a surface location  18  to a depth  20 . The wellbore  14  is shown lined with a casing  22 , however it should be appreciated that in other embodiments the wellbore  14  may not be cased. In various embodiments, the work string  12  includes a conveying member  24 , such as an electric wireline, and a downhole tool or assembly  26  (also referred to as the bottomhole assembly or “BHA”) attached to the bottom end of the wireline. The illustrated downhole assembly  26  includes various tools, sensors, measurement devices, communication devices, and the like, which will not all be described for clarity. In various embodiments, the downhole assembly  26  includes a measurement module  28 , which will be described below, determining one or more properties of the formation  16 . In the illustrated embodiment, the downhole tool  28  is arranged in a horizontal or deviated portion  30  of the wellbore  14 ; however it should be appreciated that the downhole tool  28  may also be deployed in substantially vertical segments of the wellbore  14 . 
     The illustrated embodiment further includes a fluid pumping system  32  at the surface  18  that includes a motor that drives a pump to pump a fluid from a source into the wellbore  14  via a supply line or conduit. To control the rate of travel of the downhole assembly, tension on the wireline  24  is controlled at a winch on the surface. Thus, the combination of the fluid flow rate and the tension on the wireline may contribute to the travel rate or rate of penetration of the downhole assembly  26  into the wellbore  14 . The wireline  24  may be an armored cable that includes conductors for supplying electrical energy (power) to downhole devices and communication links for providing two-way communication between the downhole tool and surface devices. In aspects, a controller  34  at the surface is provided to control the operation of the pump and the winch to control the fluid flow rate into the wellbore and the tension on the work string  12 . In aspects, the controller  34  may be a computer-based system that may include a processor  36 , such as a microprocessor, a storage device  38 , such as a memory device, and programs and instructions, accessible to the processor for executing the instructions utilizing the data stored in the memory  38 . 
     As described above, the illustrated embodiment includes the measurement module  28 . As will be described below, in various embodiments, the measurement module  28  may include one or more piezoelectric helm resonators for determination of various fluid properties within the wellbore  14 . For example, oil and gas products may enter an annulus and flow along the BHA  26 . At least a portion of that flow may be redirected into the measurement module  28 . Within the measurement module  28 , or proximate the measurement module  28  in certain embodiments, one or more fluid properties may be measured to facilitate wellbore operations. Furthermore, it should be appreciated that while various embodiments include the measurement module  28  incorporated into a wireline system, in other embodiments the measurement module  28  may be associated with rigid drill pipe, coiled tubing, or any other downhole exploration and production method. 
     In some embodiments, the measurement module  28  includes a fluid analysis tool.  FIG.  2    illustrates a perspective view of a fluid analysis tool  40  in an expanded position, in accordance with example embodiments. As illustrated, in some embodiments, the fluid analysis tool  40  includes a plurality of arms  42  movable from a retracted position into an expanded position. In some embodiments, the plurality of arms  42  are fixed at opposing ends  44 ,  46  and bendable at least one location (e.g., pivot) between the opposing ends  44 ,  46 . The plurality of arms  42  are arranged about a central axis  48  of the system, such that the plurality of arms  42  expand away from the central axis  48  to move into the expanded position and contract towards the central axis  48  to position into the retracted position. In some embodiments, the tool may include a central body  50  substantially align with the central axis  48 . The central body  50  may be configured to receive or store the plurality of arms  42  in the retracted position. In some embodiments, the central body  50  may include recessed portions  56  for receiving the arms and may include additionally recessed portions  58  for receiving the fluid sensors and/or flow spinners on the arms. 
     In some embodiments, each of the plurality of arms  42  includes one or more fluid sensors  52  coupled thereto. At least one of the fluid sensors  52  includes a piezoelectric helm resonator, an optical sensor, and a spectroscopy sensor. As will be discussed in further detail below, the piezoelectric helm resonator includes a strain bar comprising a first side, a second side opposite the first side, a first end, and a second end opposite the first end. The piezoelectric helm resonator further includes a pair of electrodes, in which a first electrode of the pair of electrodes is positioned on the first side and a second electrode of the pair of electrodes is positioned on the second side. The piezoelectric helm resonator further includes a pair of tines, in which a first tine of the pair of tines is coupled to the first end and a second tine of the pair of tines is coupled to the second end, the pair of tines each having an arc, and such that strain across a transverse face of the strain bar generates a resonance response from the pair of tines. The optical sensor is positioned centrally with respect to the piezoelectric helm resonator, and the spectroscopy sensor is positioned symmetrically with respect to the piezoelectric helm resonator in at least on direction. 
     There may be a plurality of fluid sensors  52  on each arm, as illustrated in  FIG.  2   , and thus a plurality of fluid sensors  52  on the tool  40 , which could be used for production logging. The plurality of fluid sensors  52  may be the same type of device or multiple types of devices. The fluid sensors  52  are individually addressable, such that the data obtained from each fluid sensor  52  can be associated with the respective sensor. Since each fluid sensor  52  is in a different position and thus different location in the wellbore, the data from each fluid sensor  52  can be associated with a specific location in the wellbore. 
     The fluid sensors  52  may be coupled to the respective arm  42  via a pivot and configured to swing inwardly away from the respective arm  42  towards a central axis  48  or central body  50  of the tool  40 . Alternatively, in some embodiments, the fluid sensors  52  may be configured to swing outward away from the respective arm  42  and away from the central body  50  or to the side in a direction tangential to a central axis  48  of the tool  40 . The fluid sensors  52  may be movable from a stored position to a deployed position relative to the respective arm  42  on which a fluid sensor  52  is located. In the stored position, the fluid sensors  52  may be stored in the arms  42 . In the deployed position, the fluid sensors  52  are extended out from the arms  42  and positioned substantially parallel to the axis of the borehole. In some embodiments, the fluid sensors  52  are at an angle within certain degrees from an axis of a borehole in which the system is positioned. Thus, the fluid sensors  52  are positioned to substantially face the direction of fluid flow through the borehole. In some embodiments, at least one of the plurality of arms  42  comprises a flow spinner  54  located thereon to direct the fluid flow for alignment with the fluid sensors  52 . 
     In the illustrated example embodiments, the tool includes six arms  42 , with two fluid sensors  52  and two spinners  54  integrated into each arm  42 . The sensors  52  and spinners  54  may each be articulated with a four-bar mechanism that compensates for the deployment angle of the array arms  42  to maintain the sensors  52  and spinners  54  to within ±5 degrees orientation to the borehole axis regardless of the arm&#39;s deployment angle, as illustrated below with respect to  FIGS.  3 A,  3 B, and  3 C . The four-bar mechanisms may also nest the sensor\spinner array in the tool chassis pockets upon array retraction. Other pivoting or positioning mechanism may be employed to achieve the same or similar movement dynamics. 
       FIG.  3 A  illustrates the fluid analysis tool in the retracted position  60 , in accordance with example embodiments. As mentioned, in some embodiments, the plurality of arms  42  are arranged about a central body  50  ( FIG.  2   ) of the tool  40 . The central body  50  may be configured to receive or store the plurality of arms  42  in the retracted position. Each of the arms  42  may be the same length as the receiving portion of the central body  50  such that each arm  42  may be substantially flush against the central body  50 , creating the minimum circumference of the tool  40 . The fluid analysis tool may be lowered downhole in the contracted position and then deployed into an expanded position. 
       FIG.  3 B  illustrates the fluid analysis tool  40  in a first expanded position  62 , in accordance with example embodiments. For example, this position may be used for deployment in a 5″ casing. As illustrated, in the first expanded position  62 , each of the arms  42  bends outward, putting the arms  42  at an angle with respect to the central body  50 . The fluid sensors  52  and flow spinners  54  are also deployed out from the arms  42  at an angle from the respective arm  42 .  FIG.  3 C  illustrates the fluid analysis tool in a second expanded position  64 , in which the arms  42  expand further outward than in the first expanded position  62 . For example, this position may be used for deployment in a 10″ casing. Similar to the first expanded position  62 , in the second expanded position  64 , each of the arms  42  bends outward at an angle and the fluid sensors  52  and flow spinners  54  are deployed out from the arms  42 . In the second expanded position  64 , the arms  42  are at a larger angle from the central body  50 . However, the fluid sensors  52  and flow spinners  54  also deploy at a larger angle from the arms  42 , compensating for the larger angle between the arms  42  and the central body  50 . Thus, the fluid sensors  52  and flow spinners  54  are maintained at a minimal angle from the central body  50  or central axis  48  of the tool  40 . As mentioned, the tool  40  may be designed to maintain the fluid sensors  52  and flow spinners  54  within ±5 degrees orientation to the borehole axis. 
       FIG.  4    is a graph  70  illustrating the deployment angles  72  of the arms  76 , the fluid sensors  78 , and the flow spinners  80  with respect to the casing inner diameter  74 . As illustrated, the deployment angle of the arms  76  increases as the casing inner diameter  74  increases, as the arms expand further outward for larger boreholes. However, as the deployment angle of the arms  76  gets larger (i.e., tool expands further outward), the angles of the fluid sensors  78  and flow spinners  80  do not continue to increase accordingly. Rather, it stays within ±5 degrees regardless of the angle of the arms  76 . Various embodiments and implementations of the tool may allow for different ranges. For example, some embodiments may be rated for ±2 degrees, ±10 degrees, etc. 
       FIG.  5    illustrates a perspective view of a downhole fluid analysis device  90 , such as the fluid sensors in the fluid analysis tool of  FIG.  2   , in accordance with example embodiments. The downhole fluid analysis device  90  includes a piezoelectric helm resonator  92 , an optical sensor  94 , and a spectroscopy sensor  96 . The piezoelectric helm resonator  92  includes a strain bar  98  comprising a first side  100 , a second side (not in view) opposite the first side  100 , a first end  102  and a second end  104  opposite the first end  102 . The piezoelectric helm resonator  92  further includes a pair of tines  106 ,  108 , in which a first tine  106  of the pair of tines is coupled to the first end  102  and a second tine  108  of the pair of tines is coupled to the second end  104 . In some embodiments, the tines  106 ,  108  each have an arc, such that strain across a transverse face of the strain bar  98  generates a resonance response from the tines  106 ,  108 . It should be appreciated, and will be described further below, that the strain bar  154  may also be referred to as a Poisson strain bar and, moreover, may not have a uniform thickness across its length. That is, various portions of the straight bar  154  may be adjusted or otherwise formed in order to reduce weight, induce a certain resonance frequency, create and/or eliminate certain sensitivity to fluid properties, and the like. 
     The piezoelectric helm resonator  92  further includes a pair of electrodes located thereon, in which a first electrode  110  of the pair of electrodes is positioned on the first side  100  and a second electrode (not in view) of the pair of electrodes is positioned on the second side. In some embodiments, the pair of electrodes is coupled to an electric circuit comprising a signal coupling or tuning device. The piezoelectric helm resonator receives electrical energy from the electrodes  110 . In various embodiments, the electrical energy transmitted from the electrodes  110  induces a vibration within the piezoelectric helm resonator  92 , for example due to resonant displacement as a result of electrodes  110  arranged on the piezoelectric helm resonator  92 . This vibration may be utilized to measure one or more properties of fluid surrounding and/or flowing along the piezoelectric helm resonator  92 . 
     In the illustrated embodiment, the piezoelectric helm resonator  92  design is based on the combination of a Poisson strain bar  98  and a symmetric pair of vibratory helm-geometry tines  106 ,  108 . The helm tines  106 ,  108  are excited by placing an electrical voltage across opposing faces of the transverse thickness of the piezoelectric strain bar  98  segment to develop an oscillatory contraction/expansion of the bar thickness. Due to the Poisson&#39;s ratio effect, this through-thickness oscillatory motion develops a longitudinal oscillatory displacement along the length of the bar  92  that excites the helm tines  106 ,  108  into resonance response. Due to the helm geometry of the tines  106 ,  108 , the frequency and bandwidth of the resonance response is dependent upon the visco-acoustic properties of the fluid surrounding the tines  106 ,  108 . This characteristic can be used to determine the visco-acoustic properties of the fluid, namely fluid density, viscosity, and sound speed, from measurement of the electrical admittance spectrum (50-60 kHz) on the piezoelectric resonator driving circuit. 
     The optical sensor  94  is positioned centrally with respect to the piezoelectric helm resonator  92 , and the spectroscopy sensor  96  is positioned symmetrically with respect to the piezoelectric helm resonator  92  in at least one direction. 
     In some embodiments, the fluid analysis device  90  also includes a flow meter comprising a resistance thermometer detector. In some embodiments, such as in the illustrated embodiment, the spectroscopy sensor may be an electromagnetic spectroscopy sensor, in which the electromagnetic spectroscopy sensor comprises at least one electromagnetic spectroscopy coil  116  located on at least one of the pair of electrodes  110 . In the illustrated embodiment, there are four coils  116  in total, with two coils  116  located on each electrode. Thus, there are two coils  116  on the first  100  side of the piezoelectric helm resonator  92  and two coils on the second side of the piezoelectric helm resonator  92 . These coils  116  may develop an electromagnetic dipole field in the fluid in order to obtain an electromagnetic impedance spectroscopy for the fluid. 
     In some embodiments, the device  90  may include a dielectric spectroscopy sensor, in which the dielectric spectroscopy sensor includes electrodes spaced apart to allow fluid to fill a space between the electrodes. Thus, the fluid can be analyzed using dielectric spectroscopy techniques. In certain such embodiments, the spectroscopy sensor can utilizes the pair of electrodes on the piezoelectric helm resonator. For example, the pair of electrodes on the piezoelectric helm resonator may each include a portion extending into the fluid such that a portion of fluid is between the electrodes. As would be understood, in various embodiments the dielectric constants of water, rock, and oil may be used to estimate water content in a downhole formation. In various embodiments, this information may be utilized to determine the conductivity of the fluid sample. Furthermore, the conductivity may further be used, at least in part with a machine learning method, in order to provide a quantitative assessment of contamination, as will be described further below. 
     Dielectric assessment of materials including fluids has been shown as an effective method for electromagnetic characterization of a broad range of materials, fluids, chemical products, fluid mixes, and composites. The interaction of a material with an applied electric field can be evaluated with dielectric spectroscopy techniques. The complex relative permittivity of liquids and gases depends on the dielectric constant, loss factors, chemical composition, material physical structure, frequency and temperature. Complex dielectric permittivity includes a real component and an imaginary component. The real component of the complex dielectric permittivity is the dielectric constant and the imaginary component is the loss factor component. 
     Various instruments can measure complex dielectric permittivity with varying range of measurement capabilities such as impedance analyzers, scalar network analyzers, vector network analyzers (VNA), Time-Domain Reflectometry meter (TDR), and Frequency-Domain Reflectometry meter (FDR). Different instrumentation probes types are available for either reflection or transmission based measurements. For example a Fourier Transform obtained from a reflectogram of the sensor responding to an excitation pulse can provide the frequency spectrum of complex dielectric permittivity. Over the frequency range of electromagnetic spectroscopy, various physical dielectric response mechanisms of fluid materials are measured under the effect of electromagnetic fields for each frequency region. From low frequency to higher frequencies, the following fluid flow physical polarization mechanisms are activated and sensed by the electromagnetic spectroscopy probes: ionic conductivity (10 3  to 10 9  Hz), dipolar (10 7  to 10 9  Hz), atomic level (10 9  to 10 14  Hz), electronic (10 14  to 10 16  Hz). 
     The electromagnetic spectroscopy, including the electromagnetic dielectric spectroscopy of the present disclosure, includes the fluid materials&#39; complex relative permittivity spectrum over the frequency range of interest. The electromagnetic dielectric spectroscopy can be performed over a dipolar frequency range, including the helm resonator resonating frequency range with the helm resonators&#39; electrode probes. In some embodiments, electromagnetic dielectric spectroscopy can be performed at lower frequency range up to the frequency region of the helm resonating frequency region with an added circuit, such as the circuit illustrated in  FIG.  7   , which senses fluid capacitance C f , which is associated with the flowing fluid dielectric permittivity. At very low frequencies the parallel complex impedance of the circuit illustrated in  FIG.  7    will be dominated by the impedance of the RTD f  (real component) as C f  impedance will be very large in this low frequency range. RTD f  can be extracted under these low frequency measurement conditions.  FIG.  5    also illustrates two capacitor plates  120 (C f -A) and  122  (C f -B) from a capacitor C f,  which are exposed to fluid. An RTD f    124  is also exposed to fluid. In one embodiment, RTD f  could be electrically isolated from the fluid by a thin thermally conductive layer applied to the sensing sensor surface exposed to the fluid. 
     As the measurement frequency is increased within the low frequency range, the complex impedance may show measurements sensitive to both RTD f  and C f . The complex impedance of C f  may show sensitivity to fluid flow dielectric permittivity and also to the fluid ionic ohmic loss (heat), both of which could be resolved with multiple frequency measurements given RTD f  was resolved in the very low frequency end of the measurement spectrum. There are correlation dependencies between the complex dielectric properties described here and other chemical and physical properties of the fluid flow with multiple phase components, including emulsions, surfactants, production injection additives and a variety of flow contaminants. The chemical and physical properties could include at least density, viscosity, and sonic speed. The respective correlations between such properties and the complex dielectric spectroscopy data could be processed and applied with a machine learning system to provide automated or semi-automated production fluid flow interpretation, diagnostics, analysis, and reservoir production development and flow assurance management decision making. 
     In some embodiments, the fluid analysis device  90  further includes a connection interface  118 , such as a coaxial stab connection, for providing power and/or communication connections. The connection interface  118  may include an electrical connection coupled to the pair of electrodes  110 , an acoustic channel for the piezoelectric helm resonator  92 , and an optical channel for the optical sensor  112 . In some embodiments, the interface  118  may include a channel coupled to and shared by the piezoelectric helm resonator  92  and the spectroscopy sensor  114 , in which the channel carries an acoustic signal generated by the piezoelectric helm resonator  92  and an electrical signal generated by the spectroscopy sensor  114 . The connection interface  118  may couple to fluid analysis device  90  to a cable so that power can be delivered to the fluid analysis device  90  and data can be transmitted from the fluid analysis device  90  to a controller or control station. The cable may be a coaxial cable with concentric feedthrough. The coaxial cable may include a center core fiber for carrying optical data. The cable may include concentric coaxial conductor having cylindrical geometry or helical geometry. The connection interface  118  may be configured to be compatible with various different types of cables. 
       FIG.  6    illustrates a perspective view of the piezoelectric helm resonator  92 , in accordance with example embodiments. As mentioned, the piezoelectric helm resonator  92  includes a strain bar  98  comprising a first side  100 , a second side (not in view) opposite the first side, a first end  102 , and a second end  104  opposite the first end  102 . In various embodiments, a fillet  122  or other connection is positioned between the strain bar  98  and the tines  106 ,  108 . As illustrated, the fillet  122  is curved, which reduces stresses between the strain bar  98  and the tines  106 ,  108 . The piezoelectric helm resonator  92  further includes a pair of electrodes, in which a first electrode  110  of the pair of electrodes is positioned on the first side  100  and a second electrode (not in view) of the pair of electrodes is positioned on the second side opposite the first side  100 . In some embodiments, an optical port  120  or orifice is formed through the center of the strain bar  98  such that the optical sensor  94  ( FIG.  5   ) can extend there through or at least provide a sensing window for the optical sensor  94 . 
       FIG.  7    illustrates an example circuit  160  that can be used with embodiments of the present disclosure. The circuit  160  includes some electric circuit components, including diodes D1  166  and D2  168 , which may be embedded in the multi-sensor assembly  90  of  FIG.  5    in order for the several sensor measurements to be performed over two wires. As illustrated, the resonator  170  is connected in parallel with the RTD f    172  and capacitor C f    174 . Other electrical circuit embodiments to enable multiple sensor measurements over two wires could involve MOSFET&#39;s switching, relay, selective frequency dependence circuits, Zener diode, etc. These two wires are routed to the deployment arm mount in the tool assembly  40  of  FIG.  2   , connecting to circuit terminals T1  162  and T2  164  via a pressure bulkhead feed through.  FIG.  8    illustrates a cross-sectional diagram view  180  of the sensor of  FIG.  5   , in accordance with example embodiments. As illustrates, the RTD f    182  and capacitor plates  184 ,  186  are located on the sensor and exposed to the fluid. Wires  192 ,  194  extend into the sensor, coupling to the RTD f    182  and capacitor plates  184 ,  186 , as well as the resonator  188 . The wires  192 ,  194 , along with the optical channel  190 , extend out of the sensor, forming a connection interface. 
       FIG.  9    illustrates an example waveform  200  associated with operation of the circuit of  FIG.  7   . When the voltage terminal T1 with respect to terminal voltage T2 is negative, diode D1 is OFF and diode D2 is ON. In this diode ON-OFF bias condition, the measurements across terminals T1 and T2 of complex impedance of respective fluid sensors RTD f  and C f  are performed over a frequency range. The parallel complex impedance (i.e., amplitude and phase) of fluid sensor resistor RTD f  in parallel with fluid capacitance C f  is evaluated over a frequency range. RTD f  can be separately evaluated in the real component of the complex impedance vector and C f  can also be separately evaluated in the imaginary component of the complex impedance vector. 
     When the voltage terminal T1 with respect to terminal voltage T2 is positive, diode D1 is ON and diode D2 is OFF. In this diode ON-OFF bias condition, the measurements across terminals T1 and T2 of complex impedance of the helm resonator is evaluated over a frequency range of interest (e.g. amplitude and phase). Measurements of complex impedance for Helm Resonators provide sensor data for fluid density, viscosity and sonic speed determination. Shown in  FIG.  5    are elements for RTD f , C f  (C f -A and C f -B capacitor plates) and Helm resonators which are embedded in the multiple-sensor pressure feedthrough assembly  90  and their elements are exposed to the fluid to perform fluid sensing functions. Circuit components D1 and D2 are also mounted in the multiple-sensor pressure feedthrough assembly but are not exposed to and not in contact with the fluid but are protected from the surrounding fluid(s) and respective pressure. 
       FIG.  10    illustrates another example embodiment of a circuit  220  that can be used with embodiments of the present disclosure. Instead of diodes, the circuit  220  of  FIG.  10    includes a MOSFET  222  (metal-oxide-semiconductor field-effect transistor) for switching between measurements modes. Accordingly,  FIG.  11    illustrates a waveform  240  for operation of the circuit of  FIG.  10   . Other electrical circuit embodiments can be used to combine these multiple sensor measurements over a two-wire connection. C f  plates exposed to the fluid primarily detect the fluid capacitance C f  whose measurements are dependent on the fluid relative permittivity (dielectric constant). 
     The fluid capacitance C f  measurement reads higher for higher relative permittivity fluid (e.g. water with ϵ w =80), and reads lower for lower relative permittivity fluids (e.g. oil with ϵ oil =2.2 or air with ϵ air =1), providing indications of the type of fluid present in the production flow line. Some constant fluid independent parasitic capacitance associated with capacitor&#39;s plate protective thin layer is present in series with each capacitor plate of the fluid capacitance C f , which can be accounted for during the complex impedance measurement evaluation to extract the C f  from the net imaginary component complex impedance measurement. The fluid temperature sensor RTD f  is a Resistance Temperature Detector (RTD) or optionally with silicon-based MEMS chip for example. The RTD may provide fluid measurements calibration data and complementary thermal conditions of the fluid (e.g. heat capacity evaluation), which affects the density, sonic speed and viscosity piezoelectric helm resonator measurements. 
     The RTD f  measurement can provide additional measurements such as Thermal Mass Flow. Thermal. mass flow indicates the mass flow rate of gases and liquids directly evaluated in a point or sensed area. Mass flow measurements are unaffected by changes in viscosity, density, temperature or pressure. In this type of thermal immersion or immersible type flow meter, the heat is transferred to the boundary layer of the fluid flowing past and over the heated surface (heated directly or indirectly). 
     In some embodiments, such as in the illustrated embodiment, the electrode  110  extends an electrode length, which is less than the length of the strain bar  98 . 186 . However, it should be appreciated that in various embodiments the length of the electrode may be substantially equal to the length of the strain bar  98 . In various embodiments, a surface area of the electrode  110  may determinate, at least in part, a magnitude of an emitted signal. Accordingly, a larger surface area may induce more movement of the piezoelectric helm resonator  90 , as well as improve a signal/noise ratio associated with the helm resonator sensor  90 . The electrode  110  also includes an electrode height, which is less than a height of the strain bar  98 . However, in various embodiments, the heights of the electrode  110  and the strain bar  98  may be substantially equal. It should be appreciated that certain terms such as height, thickness, width, and the like may be used interchangeably to describe various properties of the piezoelectric helm resonator  92 . These terms may be interchangeable due to the three dimensional coordinate system and the point of view that the piezoelectric helm resonator  92  is viewed. For instance, a height (substantially up and down relative to the page) may be viewed as a width (substantially left to right relative to the page) based on the perspective at which the piezoelectric helm resonator  92  is viewed. 
     Embodiments of the present disclosure provide an optical sensor  94  capable of three phase measurements for downhole logging. Techniques of the present disclosure utilize Attenuated Total Internal Reflection (ATIR) spectroscopy for the detection of different fluid phase fraction. The ATIR spectroscopy technique is based on light passing through a sensing element that is in contact with the sample under investigation and interacting with it through multiple total internal reflections where each reflection results in an evanescent wave and absorption of energy into the sample. The intensity of absorption for each fluid type depends on the wavelength. The amount of light absorbed by the sample at different wavelengths/frequencies depends on the presence and concentration of each constituent. Therefore, the absorption spectrum of the sample, or the frequency distribution of the absorbed light, can be used to identify the composition of the sample. Currently, commercial production logging tools only distinguish liquid from gas but not oil from water. The present disclosure aims to distinguish all three phases (oil, water, gas) by using optical absorption spectroscopy along with sample fluorescence and physical property measurements (fluid density, viscosity, and sound speed) made by a co-located helm piezoelectric resonator. By utilizing multiple types of measurements, the redundant information provides confirmation of the three-phase analysis. 
     Transmission absorption spectroscopy requires samples that are substantially optically translucent in the range of frequencies being studied. Therefore, conventional transmission absorption spectroscopy is difficult or impossible for analysis of very dark or opaque samples. In various embodiments, for opaque liquids and slurries, attenuated total internal reflection spectrophotometry (also known as “ATR” or “ATIR” spectrophotometry) is used where internal reflection of the light occurs at the interface between two media having different refractive indices. The attenuation of the light beam on reflectance is proportional to the change in refractive index between the two media at the interface. Because the refractive index tends to change markedly near absorption bands and becomes complex with an imaginary, absorptive component, the ATIR spectrum of a substance is similar to its absorption spectrum. In general, the ATM spectrum of a sample is independent of the true thickness of the sample, but varies depending on the angle of incidence of the incident light, which determines the penetration depth of the evanescent wave beyond the sapphire tip into the fluid, which constitutes the effective sample thickness or transmission path length, which is typically 50 to 100 microns. The smaller the angle of incidence, the greater the penetration into the sample fluid. However, the angle of incidence should be greater than the critical angle for total internal reflection to occur. 
       FIG.  12    is a representation  300  of the optical sensor  94  of present embodiments. Specifically,  FIG.  12    illustrates light of multiple wavelengths traveling from an optical source  302 , through the optical tip  304  that is adjacent a sample fluid  308 , and to a detector  306 , in accordance with example embodiments of the present disclosure. In some embodiments, 2 or 3 color LED or laser light sources are used whose photons may be absorbed almost solely by its corresponding target-species (e.g., gas, oil, water). Infrared light induced evanescent-field absorption causes attenuation of light at an absorption peak (1450 nm) of water when the fluid is water. In principle, the same approach could be used for oil at a wavelength (1740 nm) where oil has an absorption peak. However, a more convenient approach when the fluid is oil, uses blue light induced evanescent-field penetration into the fluid, which induces fluorescence (primarily from aromatics) and absorption (primarily from asphaltenes) in the oil. Water and natural gas do not fluoresce. Both 1450 nm infrared and 405 nm blue light are substantially not absorbed by natural gas. In some embodiments, two wavelengths of light can be used as the light source. For example, one such wavelength may be 405 nm, which is the wavelength that may induce fluorescence in oil. The other wavelength may be 1450 nm, the wavelength that is effectively absorbed by water. An optional third light may be used for reference measurement. Light is emitted from the two sources down a single fiber to the bi-conical tip, where the light interacts with the media and is then reflected from the end of the tip and returned back down the fiber to photodetectors. An optical system, such as illustrated in  FIG.  17   , is configured to manage the combination and splitting of the emitted and returned light for the two wavelengths. 
       FIG.  13    illustrates a detailed representation  310  of the behavior of the emitted light at the interface  312  of the optical tip  304  and the sample fluid  308 , and shows the reflection and attenuation of light through the optical tip  304 , in accordance with example embodiments of the present disclosure. Light passing through the optical tip  304  interacts with the adjacent sample fluid  308  through multiple total internal reflections  314  where each reflection results in an evanescent wave  316  and absorption of energy in the sample fluid  308 . The intensity of absorption for each fluid type depends on the wavelength of the source light. 
     In some embodiments, the optical sensor is designed such that it can generate multiple reflection points  316  along the optical length of the optical tip  304 . For example, the light source  302  may be positioned with respect to the optical tip  304  at designated incidence angle in order to produce the multiple reflection points  316 . For each of the reflection points  316 , an evanescent field  316  is generated whose wavelength is the same as the incident wavelength, as shown in  FIG.  13   . The loss in intensity due to absorption by the sample fluid is generally proportional to the number of reflection points. In some embodiments, the design target is to maximize the number of reflections (e.g., 50-100). The intensity of each reflection also depends on the loss of beam power due to absorption of the evanescent wave for a single reflection event. The primary choice for sensing element material for downhole application is sapphire due to its high refractive index (1.75) compared to the fluid media of interest, its hardness (9 on the Mohs scale) against scratching, and its ability to be machined and polished into useful profiles, and its high chemical resistance. Different sapphire sensing tip designs may be used in different cases, as illustrated in  FIG.  16   . 
       FIG.  14    illustrates a side view of the optical tip  304  in accordance with example embodiments of the present disclosure. The optical tip  304  is immersed into the media such as a sample fluid to be detected. In example embodiments, the optical tip  304  has a bi-conical shape. In some embodiments, the optical top  304  is a sapphire fiber.  FIG.  15    is line drawing illustrating the profile  330  of such a bi-conical optical tip  304 . Light emitted from the light source  302  ( FIG.  5 A ) is transmitted into a single fiber to the bi-conical optical tip, where the light interacts with the surrounding media (e.g., sample fluid) and is then reflected from the end of the optical tip  304  and returned back out of the optical tip  304  where it is detected by the photodetectors. The makeup of the sample can be determined based on the spectral content of the returning light detected by the photodetector. Thus, increasing the spectral differences caused by the different media can improve the data signal. The returned light is registered by a spectral analyzing receiver such as a spectrally resolved detector that measures the relations between power/intensity of different wavelength, which corresponds to different components of the media. The bi-conical design of the optical tip  304  of the present disclosure aims to optimize these measurements. The bi-conical shape facilitates total internal reflection throughout the entire optical tip  304  due to the angles, so that the maximum amount of light is returned to the detector, rather than lost out of the optical tip  304 . This allows for a more robust signal from which a clearer measurement can be made with respect to the content of the sample. 
     In some embodiments, the optical tip  304  comprises a first conical portion  322  and a second conical portion  324 , the first conical portion  322  positioned relatively proximal to the light source  326  and the second conical portion  324  forming a distal end of the optical tip  304 , wherein the first conical portion  322  has a slope of a first angle and a second portion  324  has a slope of a second angle steeper than the first angle. In some embodiments, the optical tip  304  includes a cylindrical or straight portion  328  relatively more proximal to the light source  326  than the conical portions  322 ,  324 . 
       FIG.  16    illustrates a plurality of example configurations of bi-conical optical tips  330 , in accordance with example embodiments. The optical tips may have varying slopes and angles for the conical portions. Depending on various design and application factors, different configuration of bi-conical optical tips may optimally facilitate total internal refraction and minimize signal loss. 
       FIG.  17    is a diagram illustrating an optical system  340  for the optical sensor, in accordance with example embodiments of the present disclosure. The optical system  340  includes a first light source  342  for emitting light in the visible light spectrum and a second light source  344  for emitting an infrared light. In some embodiments, the combination of such light sources may be referred to as one light source. In some embodiments, light emitted from both sources travel through respective aspheric lens  346 ,  348 . The visible light and the infrared light both then arrive at a beam combiner  350  and get combined into a single beam of source light. In some embodiments, the single beam of source light then travels through a beam splitter  352 , where a portion of the source light is redirected to a detector  354  for reference/calibration purposes. The remaining portion of the source light travels through the beam splitter  352  and through a mirror  356  to the optical tip  358  wherein it can interact with the sample fluid. Light returning from the optical tip  358  theoretically includes portions of both the visible light and the infrared light. The actual content of the returning light depends on the makeup of the sample fluid and corresponding attenuation of the light components. The returning light reaches a dichroic mirror  356 , where a portion of the visible light is redirected towards a visible light detector  362 . In some embodiments, the redirected visible light may travel through one or more of a lens  364  or filter  366  before the visible light detector  362 . The rest of returning light travels through the dichroic mirror  356  and is redirected at the beam splitter  352  to a second bicolor detector  368 , where measurements on the returning light are made to determine the makeup of the sample. There may be fewer or more lens, filters, and the like, positioned at various positions for various effects. 
       FIG.  18    is a flow chart of an embodiment of a method  130  for collecting and analyzing data utilizing the downhole fluid analysis device  90 . It should be understood that, for any process described herein, that there can be additional, alternative, or fewer steps performed in similar or alternative orders, or concurrently, within the scope of the various embodiments unless otherwise specifically stated. The illustrated method  130  includes positioning  132  a fluid sensor in a wellbore, in which the fluid sensor comprising co-located piezoelectric helm resonator, optical sensor, fluid capacitance, resistance temperature detector, thermal mass flow meter and electromagnetic spectroscopy sensor. Co-location is important because, for correct interpretation, we want all sensors to be reading the same fluid at the same time. 
     The method further includes applying  134  electrical energy to the piezoelectric helm resonator to excite the piezoelectric helm resonator, receiving  136  a first signal from the piezoelectric helm resonator, and determining  138  one or more of density, viscosity, or sound speed of a region of fluid in the wellbore based at least in part the one or more signals from the piezoelectric helm resonator. Multiple fluid sensor time series measurements are acquired over a period of time and in various points spatially distributed around the fluid flow path cross-section inside the tubular. These flow cross-section spatial distributions recorded over a time interval as time series data arrays can be used to construct mass and volume three phase flow imaging, providing a visualization of multiple phase fluid flow patterns and colors indicating fluid characteristics and fluid types flowing inside the tubular. 
     These multiple phase fluid flow visualizations can be used for reservoir wells production evaluation and diagnostics, leading to intervention, injection stimulus, and remediation procedures required for performing reservoir and well flow assurance program goals. The method also includes receiving  140  a second signal from the optical sensor, determining  142  one or more optical properties of the region of fluid based at least in part on the second signal, receiving  144  a third signal from the spectroscopy sensor, and determining  146  one or more spectroscopy characteristics of the region of fluid based at least in part on the third signal. In some embodiments, various additional interpretive steps can be performed back on the detected information. For example, the method may also include evaluating  148   a  fluid characteristics (e.g., fluid types), and/or imaging  148   b  fluid types and flow in the wellbore or in the tubulars. 
     In some embodiments, the density, viscosity, sound speed, one or more optical properties, and one or more spectroscopy characteristics are associated with the same fluid domain and time. At least some of these parameters can be used to further estimate other in situ characteristics of the well fluid, including for example, live-oil oil holdup, live-oil gas-oil-ratio, live-oil sound speed, live-oil bulk modulus, live-oil mass density, or dead-oil mass density. In order to make these correlations the measurements for sound speed, acoustic impedance and bulk modulus of the composite fluid flow must be obtained in a specific congruent manner. That is, from a single measurement domain [M-domain] with a sensing field of interaction that is simultaneous and congruent relative to all the acoustic measurements and all the continuous/dispersed particles. The co-located nature of the piezoelectric helm resonator, the optical sensor, and the spectroscopy sensor allows such and other measurements to be made for the same fluid domain and at the time. 
     In various embodiments, the change in fundamental resonance frequency spectra of the piezoelectric helm resonator that is coupled to a fluid due to changes in the visco-acoustic properties of the local fluid volume. The design of the helm resonator creates a ‘self-equilibrated’ standing acoustic wave pattern between the opposing resonator tines and develops a localized Helmholtz resonator without the need for an external reactionary cavity wall. This phenomenon allows the sensor to be utilized in a variety of configurations, including the combination of an array of sensors distributed throughout the borehole cross section to analyze multi-phase stratified production flows. 
     For the production logging applications several design characteristics derive from the fact that the downhole environment for the application involves borehole fluid flows of significant ranges of flow speeds, a broad variety of multi-phase fluid properties to be investigated, and extreme downhole pressures and temperatures. The measurement relies on the resonant excitation of a formed volume of the fluid mixture of interest, and the sensing of the changes in resonance frequency spectra of the electrical admittance response of the sensor with changes in the volume fluid properties. The piezoelectric helm resonator functions by generating a “self-equilibrated” acoustic wave pattern in the resonance formed volume between the two sets of vibratory tines. This phenomenon creates an intrinsic Helmholtz resonator of the fluid volume between the helm tines and allows the sensor to be simply deployed in any open-field fluid domain. This then also ensures the measurement of the fluid is closely representative of the local borehole flow across the sensor. 
     A complex admittance is measured from the piezoelectric helm resonator over a frequency range, producing frequency dependent curves with corresponding phase and amplitude frequency response or its real and imaginary complex frequency response components. Quantitative numerical features extracted from the piezoelectric helm resonator&#39;s real and imaginary complex admittance amplitude and phase frequency dependent curves can be used as parameter inputs to various formulas, threshold detectors, and fluid property discriminators in one, two and three-phase fluid flow. This can be used to produce tubular mass flow and volumetric cross-section image and distribution estimate of fluid density, viscosity and sonic speed, fluid phase detection, fluid type detection, three-phase fluid type change, mixed three-phase fluid detection, mixed two-phase fluid detection, variation statistics or detection thresholds of fluid density, viscosity or sonic speed, increase or decrease of fluid&#39;s density, viscosity or sonic speed. 
     The piezoelectric helm resonator&#39;s real and imaginary complex admittance amplitude and phase frequency dependent curves, and any of their derivative curves with respect to frequency can apply their respective calculated quantitative parametric measurements for fluid property and dynamic flow behavior evaluation and mapping with formulas, threshold detectors and discriminators as discussed above. The calculated quantitative parametric measurements of these curves can include for example, but are not limited to, an integral of curve differences computed over a frequency range measured at different times or similarly an integral of difference of separately computed non-overlapping curve window moving averages for example for evaluation and determination of dynamic fluid flow behavior within the tubular. Other calculated quantitative parametric measurements include frequency at the curve&#39;s peak values, frequency difference between curve&#39;s peaks, curve differential value between positive and negative curve&#39;s peak values, frequency interval between curve derivative zero-crossings, parameter computation using the curve&#39;s derivative positive and negative peak values or frequencies at peaks (sums or differences for example), maximum curve derivatives with respect to frequency, curve peak frequency width at 50% of the peak value (or width at other chosen peak percent values). 
     The production logging diagnostic, predictive, or analytical method may use one or more curve frequency dependent values measured or derived from measured curve values. Such values can be measured in one or multiple distributed sensors, at one or different points of time, or over different time intervals. Values can be applied as inputs to formulas, threshold detectors, and discriminators evaluated with a measured or computationally derived curve. Calculated quantitative parametric measurements of the curves can be used for fluid characteristics and properties computation, along with descriptive and analytical statistics in order to evaluate and analyze production logging flow. 
       FIG.  19    is a block diagram of an embodiment of a machine learning system  250  that may be utilized with embodiment of the present disclosure. Embodiments of the present disclosure may utilize machine learning techniques to associate specific electromagnetic impedance spectroscopy with specific fluid mixtures, thus enabling not only fluid property identification but fluid mixture characterization. The machine learning techniques may include one or more neural networks (e.g., convolutional neural networks, fully connected neural networks, recurrent neural networks, etc.) to analyze how data related to electromagnetic impedance spectroscopy may relate to ground truth information related to fluid mixture characterization. In other words, the machine learning method may obtain information identifying fluid mixture characterizations based on electromagnetic impedance spectroscopy (e.g., a ground truth) and thereafter “learn” how different electromagnetic impedance spectroscopy information may correlate to that fluid characterization, as well as others. In certain embodiments, the machine learning techniques may incorporate one or more open source machine learning libraries, such as TensorFlow, scikit-learn, Theano, Pylearn2, NuPIC, and the like. 
     It should be appreciated that in certain embodiments the machine learning system  250  may be incorporated into a control system associated with the wireline/drilling system  20 . The control system may include one or more processors and memories. The memories may store instructions that, when executed by the processors, perform one or more functions. Additionally, in embodiments, the machine learning system  250  may be associated with a remote server having a processor (e.g., central processing unit, graphics processing unit, etc.) and a memory. In the illustrated embodiment, the machine learning system  250  includes a machine learning module  252  that may be trained using known information (e.g., a ground truth) such as a database  254 . In this training step, the machine learning module  252  is utilized to correlate data between fluid mixtures and their associated electromagnetic impedance spectroscopy. It should be appreciated that the machine learning module  252  may be trained using any variety of methods, such as back propagation, clustering, or any other reasonable methods. 
     As shown in  FIG.  19   , data (e.g.,  266   a ,  266   b ,  266   c ) from the fluid analysis tool  40  may be transmitted to a network  256 , for example via a network communication system, such as the Internet or the like. The network  256  may include the database  254  and/or be in communication with the database  254 , which may be stored in a data store  258  which can be a cloud storage architecture accessible by multiple data sources supplying sensorial data remotely scattered and users&#39; client base via an internet network. The data store  258  may be utilized for training purposes for the supervised or unsupervised machine learning module  252  or to transmit data to the machine learning module  252  for evaluation. It should be appreciated that data may also be transmitted directly to the machine learning module  252  from the network  256 . 
     The illustrated embodiment of the machine learning module  252  includes a convolutional neural network that takes input  260  through one or more convolutional steps  262 , which may include pooling, non-linearization (e.g., ReLu), filtering, and the like. The result of the convolutional steps  262  may be further processed to from an output  264  based on one or more parameters of the machine learning module  252 . For instance, if the machine learning module  252  is trained to identify fluid mixture properties, such as a percentage of drilling mud in the fluid, then the machine learning module  252  may output information indicative of different percentages of fluids within the fluid cavity, a predefined characterization (e.g., mud-heavy, mud-light, etc.), or a percentage of mud. In certain embodiments, this may be referred to as identification of the contamination of the fluid. 
     The foregoing disclosure and description of the disclosed embodiments is illustrative and explanatory of the embodiments of the invention. Various changes in the details of the illustrated embodiments can be made within the scope of the appended claims without departing from the true spirit of the disclosure. The embodiments of the present disclosure should only be limited by the following claims and their legal equivalents.