Dual-beam multiphase fluid analysis system and method

Abstract

A method for analyzing the flow of a multiphase fluid through a flow meter is provided. In one embodiment, the method includes transmitting two beams of electromagnetic radiation along different paths through the multiphase fluid and detecting the two transmitted beams with a detector. The method also includes determining a gas fraction and a water-to-liquid ratio of the multiphase fluid. The gas fraction is determined based on the detected first beam of electromagnetic radiation, and the water-to-liquid ratio of the multiphase fluid is determined based on the detected second beam of electromagnetic radiation. Additional systems, apparatus, and methods are also disclosed.

Description

Technical Field

[0001] The present disclosure relates to gas or oil well testing or production monitoring, and more particularly, to methods and apparatus for analyzing multiphase fluids produced from a gas or oil well. Background Art

[0002] Hydrocarbon fluids such as oil and natural gas are obtained from underground geological formations (called reservoirs) by drilling wells that penetrate hydrocarbon-bearing formations. Once a wellbore is drilled, the well can be tested to determine reservoir capacity and other characteristics of the underground formation to help make decisions about field development. Various components and equipment can be installed to monitor and perform flow tests while various fluids are being produced from a reservoir.

[0003] Well tests are performed to provide reservoir characterization, estimates of well deliverability, evaluation of completion and perforation strategies, and to assess the efficiency of operations performed on the well, such as drilling, completion, perforating, stimulation, etc. During well testing, one parameter obtained is the flow rate measured at the surface. Various types of analysis can be performed on the results of the flow test to determine formation, fluid, and flow characteristics, such as various types of analysis on data measured using flow meters. Wells typically produce a combination of water, oil, and gas, which makes flow measurement quite complex.

[0004] One traditional way to measure flow is by separating the fluid phases in a multiphase flow and then measuring the individual phases with a single-phase flow meter. The separation and measurement of single-phase flow is generally considered accurate. While single-phase flow measurements are generally trustworthy, difficulties arise when fluid separation is incomplete, providing a mixture of fluid phases to be measured by a single-phase flow meter (e.g., bubbles in oil) and the results are inaccurate. Another potential disadvantage is that some information about the dynamic behavior of the fluid flow in the production well may be missed because the fluid flow rate is measured after separation. Therefore, it is desirable to measure multiphase flow online in real time without separation using a multiphase flow meter. Summary of the invention

[0005] Certain aspects of some embodiments disclosed herein are described below. It should be understood that these aspects are presented only to provide the reader with a brief overview of some forms that the present invention may take, and these aspects are not intended to limit the scope of the present invention. In fact, the present invention may include various aspects that may not be described below.

[0006] In one embodiment of the present disclosure, a method includes receiving a multiphase fluid in a bore of a pipe and passing electromagnetic radiation having multiple energy levels through the multiphase fluid in the bore. Passing electromagnetic radiation through the multiphase fluid in the bore of the pipe includes transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the bore, and transmitting a second beam of electromagnetic radiation through the multiphase fluid along a second beam path in the bore. The second beam path is different from the first beam path, and the length of the first beam along the first beam path in the bore is greater than the length of the second beam along the second beam path in the bore. The method also includes detecting the first beam of electromagnetic radiation passing through the multiphase fluid at a first detector, and detecting the second beam of electromagnetic radiation passing through the multiphase fluid at a second detector. In addition, the method includes determining a gas fraction and a water-in-liquid ratio of the multiphase fluid in the bore. The gas fraction is determined based on the detected first beam of electromagnetic radiation, and the water-in-liquid ratio of the multiphase fluid is determined based on the detected second beam of electromagnetic radiation.

[0007] In another embodiment of the present disclosure, a method includes receiving a multiphase fluid in a hole of a pipe, the multiphase fluid flowing through the hole in an annular or annular mist state, wherein the heavier fluid of the multiphase fluid forms a liquid film along the inner wall of the pipe defining the hole. The method also includes passing electromagnetic radiation having multiple energy levels through the multiphase fluid in the hole, which includes transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path passing through the hole, and transmitting a second beam of electromagnetic radiation through the multiphase fluid along a second beam path in the hole. The second beam path is different from the first beam path, and the length of the first beam along the first beam path in the hole is greater than the length of the second beam along the second beam path in the hole. The method also includes detecting the first beam of electromagnetic radiation transmitted through the multiphase fluid at a first detector, detecting the second beam of electromagnetic radiation transmitted through the multiphase fluid at a second detector, and determining the radius of the gas core (core) of the multiphase fluid.

[0008] In another embodiment, an apparatus includes a fluid conduit having a bore and a measurement system positioned to emit multiple beams of electromagnetic radiation having multiple energy levels through a multiphase fluid received in the bore. The measurement system includes at least one radiation source, a first radiation detector positioned to receive a first beam emitted through the multiphase fluid along a first beam path from the at least one radiation source to the first radiation detector, and a second radiation detector positioned to receive a second beam emitted through the multiphase fluid along a second beam path from the at least one radiation source to the second radiation detector. The measurement system is arranged so that a length of the first beam along the first beam path within the bore is greater than a length of the second beam along the second beam path within the bore. The measurement system also includes a computer for calculating a gas fraction of the multiphase fluid based on the first beam received by the first radiation detector, and calculating a water-in-liquid ratio of the multiphase fluid based on the second beam received by the second radiation detector.

[0009] With respect to various aspects of the present embodiment, there may be various improvements of the above-described features. Further features may also be included in these different aspects. These improvements and additional features may exist alone or in any combination. For example, the various features discussed below with respect to the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief overview given above is intended only to familiarize the reader with certain aspects and contexts of some embodiments, and is not limited to the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Certain embodiments of the present disclosure will be described below with reference to the accompanying drawings, wherein the same reference numerals represent the same elements. However, it should be understood that the accompanying drawings only illustrate the various embodiments described herein and are not intended to limit the scope of the various techniques described herein. The accompanying drawings illustrate and describe various embodiments of the present disclosure. More specifically:

[0011] Figure 1 Generally depicted is a flow meter for analyzing a fluid according to one embodiment of the present disclosure;

[0012] Figure 2 According to an embodiment Figure 1 A block diagram of the components of a flow meter computer;

[0013] Figure 3 is a cross section of a pipe of a flow meter using two radiation beams to analyze a multiphase fluid within a bore of the pipe according to one embodiment;

[0014] Figure 4 is a flow chart for analyzing a multiphase fluid with two radiation beams to determine various properties of the multiphase fluid according to one embodiment;

[0015] Figure 5-7 depicts an additional example of a flow meter using two radiation beams to analyze a multiphase fluid within a bore of a pipe in accordance with some embodiments;

[0016] Figure 8 is a cross section of a pipe of a flow meter for analyzing a multiphase fluid having a liquid film surrounding a gas core using two radiation beams according to one embodiment; and

[0017] Fig. 9 According to one embodiment, a method for determining Figure 8 Flowchart of the radius of the gas core. DETAILED DESCRIPTION

[0018] In the following description, many details are set forth to provide an understanding of the present disclosure. However, those skilled in the art will appreciate that the embodiments of the present disclosure may be practiced without these details, and that various variations or modifications from the described embodiments are possible.

[0019] In the specification and the appended claims: the terms "connecting ...", "connecting", "being connected", "connected with..." and "connecting ..." are used to mean "directly connected with..." or "connected with ..." via one or more elements, while the term "set" is used to mean "one element" or "more than one element". In addition, the terms "connecting ...", "connecting ...", "being connected", "coupled together" and "coupled with ..." are used to mean "directly coupled together" or "coupled together via one or more elements". As used herein, the terms "upwardly" and "downwardly"; "up" and "downwardly"; "upstream" and "downstream"; "above" and "below"; and other similar terms indicating relative positions above or below a given point or element are used in this specification to more clearly describe some embodiments of the present disclosure. When introducing elements of various embodiments, the articles "a", "an", "the" and "said" are intended to indicate that there are one or more elements. The terms "including", "comprising" and "having" are intended to be inclusive and mean that there may be other elements in addition to the listed elements.

[0020] Certain embodiments of the present disclosure generally relate to fluid analysis, such as fluid analysis of produced fluids during well production testing or permanent production monitoring. More specifically, some embodiments include a multiphase flow meter designed to emit two beams of x-ray and / or gamma-ray electromagnetic radiation having multiple energies, the multiple energies having different path lengths through the fluid. In some examples, a first beam of radiation is emitted along a diametric path through a pipe segment of the multiphase flow meter, and a second beam of radiation is emitted along a non-diametric path through the pipe segment. The first beam of radiation and the second beam of radiation can be emitted from the same radioactive multi-energy source or from different radiation sources having multiple energies.

[0021] In at least one embodiment, the highest energy level of the beam (e.g., 133 Ba source at 356 keV) along a first diameter beam where the effect of count rate reduction along the large path length is minimal at the available energy levels and can be determined at two or more lower energies of the second beam (e.g., for 133Ba sources are 32keV and 81keV) along a second non-diametric beam across the near-wall (liquid-rich) region for water-in-liquid ratio (WLR) determination, where the count rate measured along the smaller path length decreases less. In some cases, such as during annular or annular mist flow regimes exhibiting concentric gas core and liquid annulus shapes, two beams of X-ray and / or gamma-ray radiation emitted along diametric and non-diametric paths through the fluid may also or alternatively be used to determine one or more of liquid film thickness, radius of the gas core, liquid fraction in the gas core, and water, gas, and oil fractions. In at least some cases, the present technique can improve measurement accuracy and facilitate measurement of high production flow rates in large diameter pipelines over a wide range of gas volume fractions.

[0022] Turning now to the drawings, according to one embodiment, an apparatus 10 for analyzing a fluid is generally Figure 1 . Although certain elements of the apparatus 10 are depicted in this figure and generally discussed below, it should be understood that the apparatus 10 may include other components in addition to or in place of those currently shown and discussed. In addition, while the apparatus 10 may be provided in the form of a flow meter (e.g., a multiphase flow meter), as shown here and described below in conjunction with certain embodiments, the apparatus 10 may also be provided in other forms. In addition, in at least some cases, the apparatus 10 is used to analyze fluids extracted from underground formations. Such analysis may be performed by the apparatus 10 underwater or on the surface of the fluid.

[0023] As described, the apparatus includes a fluid conduit 12 for receiving a fluid to be analyzed and various sensors coupled to the fluid conduit 12 for measuring properties of the fluid in the conduit 12. In the presently described embodiment, the sensors include a radiation detector 16 (which receives radiation from an emitter 14), a pressure transmitter 18, and a differential pressure transmitter 20. Multivariable transmitters (MVTs) for pressure, temperature, and differential pressure may be used to reduce the cost of the flow meter. The emitter 14 may emit electromagnetic radiation into the fluid, at least some of which is received by the radiation detector 16. In at least one embodiment, the emitter 14 includes a nuclear source (e.g., a nuclear source) that emits nuclear radiation through the fluid toward the radiation detector 16. 133 Ba). In various embodiments, the emitter 14 may also or alternatively include an x-ray generator that transmits x-ray radiation having multiple energy levels through the fluid to the radiation detector 16. In other embodiments, the device 10 includes multiple radiation detectors 16 positioned to receive nuclear or x-ray generator radiation emitted through the fluid by one or more emitters 14 having a nuclear or x-ray generator source. When multiple emitters 14 are used, each emitter 14 may include the same type of nuclear source (e.g., 133 Ba) or x-ray generator source, or one of the emitters 14 may have a different type of nuclear source or x-ray generator source than the other.

[0024] To facilitate certain measurements, such as flow, the fluid conduit 12 may be configured as a vertical venturi section having a tapered bore and a venturi throat to restrict fluid flow, such as Figure 1 This contraction creates a pressure drop that can be measured with a differential pressure transmitter 20. Additionally, in at least one embodiment, the emitter 14 and detector 16 are positioned about a venturi throat in the fluid conduit 12 (e.g., within the same cross-section) such that the detector 16 receives radiation that has been transmitted through the fluid within the venturi throat.

[0025] In some embodiments, the device 10 is a multiphase flow meter that uses radiation of two or more different energy levels or wavelengths. As an example, the device 10 can use gamma rays or x-ray radiation of two or more different energy levels (e.g., emitted through a venturi throat). The attenuation of the x-ray and / or gamma ray radiation of different energies can be measured and used to determine the individual phase fractions of oil, gas, and water in the multiphase fluid flowing through the flow meter. The individual phase fractions and the venturi pressure difference can be used to determine other fluid properties, such as mixture density, WLR, and mass flow rate.

[0026] The diameter of the venturi throat can vary between different embodiments. For example, for the same venturi throat / inlet diameter ratio of 0.5, a smaller diameter throat can be used for some lower flow rates and fluids, while a larger diameter throat is desirable for certain fluids at higher flow rates (e.g., for very high rate oil / gas wells). In at least some embodiments, the venturi throat of the fluid conduit 12 has an inner diameter of 60-150 mm (e.g., 65 mm or 88 mm). However, increasing the throat diameter can also increase transmission attenuation (resulting in a reduction in photon count rate, particularly at lower gamma ray or x-ray energies), such as when the brine salinity of the fluid is high (e.g., during a full water calibration of the device 10) or when the water fraction is intermittently high (e.g., during flow with a high WLR liquid slug).

[0027] The apparatus 10 also includes a computer 22 (which may also be referred to as a controller or control unit) for determining the properties of the fluid within the fluid conduit 12. In at least some embodiments, the computer 22 is provided in the form of a flow computer that is coupled to the other illustrated components in a single unit to facilitate installation of the flow meter in a larger system (e.g., an oilfield facility). More specifically, the computer 22 is operable to determine the properties of the fluid within the fluid conduit 12 based on measurements collected by the other components, such as photon count rates from one or more detectors 16. For example, the computer 22 can determine the total flow rate of the fluid based on the Venturi differential pressure and the density of the mixture. In addition, the computer 22 of the multiphase flow meter can determine the attenuation of the fluid at various energy levels of radiation by comparing the amount of radiation at various energy levels emitted from the emitter 14 with the portion of such radiation actually received by the detector 16. The computer 22 can also use this information to calculate the phase fraction (e.g., the ratio of oil, gas, and water) and the density of the mixture of the multiphase fluid within the fluid conduit 12. The flow rate of a single phase can be determined by combining the phase fraction measurement with the total flow measurement. In some embodiments, computer 22 calculates the gas fraction of the multiphase fluid based on a first beam of x-ray and / or gamma-ray electromagnetic radiation, and calculates the WLR of the multiphase fluid based on a second beam of x-ray and / or gamma-ray electromagnetic radiation, the second beam of x-ray and / or gamma-ray electromagnetic radiation having a shorter path through the fluid than the first beam, as discussed further below. Computer 22 may also or alternatively calculate the radius of a gas core within an annular multiphase fluid, the liquid fraction of the gas core, the thickness of an annular liquid film surrounding the gas core, or the gas fraction of the multiphase fluid, as described below.

[0028] The computer 22 may be a processor-based system, an example of which is shown in FIG. Figure 2. In the depicted embodiment, the computer 22 includes at least one processor 30 connected to a volatile memory 34 (e.g., random access memory) and a non-volatile memory 36 (e.g., flash memory and read-only memory (ROM)) via a bus 32. Encoded application instructions 38 and data 40 are stored in the non-volatile memory 36. For example, the application instructions 38 can be stored in the ROM and the data 40 can be stored in the flash memory. The instructions 38 and data 40 can also be loaded into the volatile memory 34 (or the processor's local memory 42) as needed, for example to reduce delays and improve the operating efficiency of the computer 22. The encoded application instructions 38 can be provided as software that can be executed by the processor 30 to enable various functions described herein. Non-limiting examples of these functions include determining: incident photon count rate on the detector, radiation decay rate, phase fraction and mixture density (oil, water and gas fraction) of a multiphase fluid, flow rate, gas volume fraction (GVF), WLR, radius of the gas core, liquid fraction of the gas core, and liquid film thickness. In at least some embodiments, the application instructions 38 are encoded in a non-transitory computer-readable storage medium, such as the volatile memory 34, the non-volatile memory 36, the local storage 42, or a portable storage device (eg, a flash drive or an optical disk).

[0029] The interface 44 of the computer 22 enables communication between the processor 30 and various input devices 46 and output devices 48. The interface 44 may include any suitable device capable of achieving such communication, such as a modem or a serial port. In some embodiments, the input device 46 includes one or more sensing components of the apparatus 10 (e.g., the detector 16, the pressure transmitter 18, and the differential pressure transmitter 20, or a pressure / temperature / differential pressure multivariable transmitter (MVT)), and the output device 48 includes a display, a printer, and a storage device that allows the output of data received or generated by the computer 22. The input device 46 and the output device 48 may be provided as part of the computer 22, or may be provided separately.

[0030] In addition, while the computer 22 can be positioned with the fluid conduit 12 and the sensing components of the device 10 as an integral system (e.g., a flow meter), the computer 22 can also be positioned away from the other components. In addition, the computer 22 can be provided as a distributed system, wherein a portion of the computer 22 is positioned with the sensing components at the fluid conduit 12, while the remainder of the computer 22 is positioned away from the fluid conduit 12. One or more communication devices (e.g., interface 44) can facilitate wired or wireless communication of multiphase flow meter measurement data (e.g., flow, WLR, GVF, or sensor prediction, diagnostic, or quality control information) to a user's process management system, such as a supervisory control and data acquisition (SCADA) system. The multiphase flow meter can receive commands from the user via such a communication device to update the multiphase flow meter configuration or calibration settings. Multiple multiphase flow meters with connectivity can form part of the Industrial Internet of Things, enabling more efficient oil and gas reservoir management through big data analysis and cloud computing.

[0031] As described above, in at least some embodiments, two radiation beams having multiple energy levels may be emitted through the fluid conduit 12 of the flow meter 10 to facilitate analysis of a multiphase fluid. Figure 3 An example of this is provided in , which shows radiation beams 52 and 54 being transmitted from the emitter 14 to the detector 16 along a cross-section of the pipe 12 through an aperture 56 generally defined by a wall 58 of the pipe 12 . Figure 3 The emitter 14 includes a single multi-energy radiation source 62, such as 133 Ba, which emits electromagnetic radiation (eg, X-rays and gamma rays) of beams 52 and 54. It will be appreciated that emitter 14 may include a collimating aperture designed to emit beams 52 and 54 toward two radiation detectors 16 (ie, first detector 66 and second detector 76).

[0032] In this depicted embodiment, beam 52 is emitted along a diametric path through hole 56 and is received at crystal 64 of first detector 66 after passing through window 68, hole 56, window 70, and collimator 72. In contrast, beam 54 is emitted along a non-diametric path through hole 56 and is received at crystal 74 of second detector 76 after passing through window 68, hole 56, window 80, and collimator 82. Detector crystals 64 and 74 may be yttrium aluminum perovskite (YAP) crystals or some other suitable material. At least in some cases, windows 68, 70, and 80 are configured as pressure-retaining, radiant energy transparent monolithic windows. Although detector 16 may be provided as a scintillation detector, other types of detectors 16 (e.g., solid-state detectors) may also or alternatively be used in other embodiments.

[0033] Due to their different beam paths, the length of second beam 54 within aperture 56 is shorter than that of first beam 52. That is, the distance traveled by first beam 52 through the multiphase fluid within aperture 56 (i.e., between windows 68 and 70) is greater than the distance traveled by second beam 54 through the multiphase fluid (i.e., between windows 68 and 80). In some cases, the path length of second beam 54 within aperture 56 may be seventy-five percent or less (or fifty percent or less) less than the path length of first beam 52 within aperture 56, and may depend on the inner diameter of aperture 56. Although beam 52 may be a diametric beam, such as Figure 3 As shown, however, the bundle 52 may also be a non-diametric bundle.

[0034] In at least some embodiments, a single high energy measurement (e.g., for 133 Ba source at 356 keV) to determine the gas fraction 90 (i.e., gas hold-up) or mixture density, and two or more low energy measurements (e.g., for 133 Ba source at 32keV and 81keV) is measured by detector 76 (DET-2) along the second beam 54 to determine WLR92 or liquid density. The low energy measurement made along the second beam 54 can also be used to calculate a second gas fraction or a second mixture density for cross comparison with the gas fraction or mixture density measured along the first beam 52 to check the level of flow inhomogeneity to improve the overall measurement accuracy. Two multi-channel analyzers (MCA) 86 and central processing unit (CPU) 88 (e.g., of computer 22) can be used with detectors 66 and 76 to perform parallel gas fraction (mixture density) and WLR determination. The energy levels at which the high energy and low energy measurements are made can vary between embodiments of the radioactive or x-ray generator source. In at least one embodiment, the high energy measurement is the count rate of gamma ray photons at energy levels within the upper half (i.e., at or above the median) of the discrete gamma emission levels of the radioactive source 62 used, and the low energy measurement is the count rate of gamma ray or x-ray photons at energy levels below the median of the discrete gamma emission levels of the source 62. In some embodiments, the high energy measurement is the count rate of x-ray and / or gamma-ray photons at the appropriate highest energy level of the emission level of the radioactive or x-ray generator source 62 used, and the low energy measurement is the count rate of x-ray and / or gamma-ray photons at other appropriate energy levels of the emission level of the source 62. Furthermore, in some embodiments, the high energy measurement is the count rate of gamma-ray photons from the source 62 at energy levels where the Compton scattering effect is the dominant x-ray or gamma-ray-matter interaction effect, and the low energy measurement is the count rate of gamma-ray or x-ray photons from the source 62 at energy levels where the photoelectric effect is the dominant x-ray or gamma-ray-matter interaction effect.

[0035] Now turn to Figure 4 , an example of a process for analyzing a multiphase fluid is generally represented by a flow chart 94. In this embodiment, the multiphase fluid is received in a conduit (box 96), such as in a bore 56 of the conduit 12. The received multiphase fluid is then irradiated (e.g., at multiple energy levels) with a first beam (e.g., beam 52) of electromagnetic radiation (e.g., x-rays and / or gamma-ray radiation) along a first beam path (box 98) and a second beam (e.g., beam 54) of electromagnetic radiation (e.g., x-rays and / or gamma-ray radiation) along a second beam path (box 100). As described above, the first beam path can have a greater length in the multiphase fluid than the second beam path. In addition, in at least some embodiments, the first beam path is a diametric beam path through the bore 56, while the second beam path is a non-diametric beam path through the bore 56.

[0036] A first detector (e.g., detector 66) receiving the first beam measures a photon count rate of one or more energy levels (e.g., one of the highest energy levels) of the first beam (block 102). Similarly, a second detector (e.g., detector 76) receiving the second beam measures a photon count rate of one or more energy levels (e.g., two or more lower energy levels) of the second beam (block 104). A gas fraction 90 of the multiphase fluid is determined based on the detected first beam (block 106), for example, according to the count rate of the first detector for the detected first beam, and a WLR 92 of the multiphase fluid is determined based on the detected second beam (block 108), for example, according to the count rate of the second detector for the detected second beam.

[0037] The mixture density or gas fraction 90 can be obtained from the highest energy in the beam 52 measured along the first beam 52 (e.g., for 133 The detector 66 receiving the first beam 52 (for gas / liquid fraction determination) may be optimized in some embodiments with respect to collimator diameter (e.g., increased to 15 mm, compared to 10 mm for some other designs) and / or scintillating YAP crystal length (e.g., increased from 10 mm to 15 mm) to make the desired count rate measurement at the highest (largely composition independent) energy in full pipe water / brine (i.e., when the pipe 12 is filled with water / brine). The gas volume fraction (GVF) for gas-liquid flow splitting may be derived from the through-diameter gas fraction determined at the venturi throat using an appropriate gas-liquid velocity slip model.

[0038] The WLR (and therefore liquid density) determination may be performed along a second beam 54 which is a beam of liquids at two or more lower energies (e.g., for 133 Ba sources at 32keV (x-ray photons) and 81keV (gamma-ray photons) and / or even lower energies (e.g., 18keV fluorescent x-rays, which are primarily produced by a portion of the 32keV photons interacting with the thin metal foil), have a shorter path length through the near-wall (liquid-rich, low GVF) region, where the increased reduction in count rate would be detrimental to the accuracy of the phase fraction measurement if followed along the longer path length of the first beam 52 through the fluid. A photon detection scheme (via detector 76) with full spectral deconvolution can be used for the second beam 54 for WLR determination. For high GVF moisture in annular or annular fog flow regimes, the non-diametric second beam 54 will interrogate the liquid-rich (locally low GVF) region near the pipe wall (e.g., vertical pipe wall 58), which can provide a more accurate WLR determination based on two (or more) energy count rate measurements. Two (or more) energy count rate measurements along the non-diametric second beam 54 can also be used to calculate a second gas fraction or a second mixture density for thorough comparison with the gas fraction or mixture density measured along the first beam 52, thereby checking the level of flow inhomogeneities to improve overall measurement accuracy.

[0039] Despite Figure 3 An example of an apparatus for analyzing a multiphase fluid having an emitter 14 and two detectors 16 is described in and as described above, but the apparatus may take other forms. Figure 5 In one embodiment shown, the apparatus includes a multiplexer (MUX) 112 that facilitates analysis of multiphase fluids using one MCA 86 and one CPU 88, rather than two MCAs. Figure 3As described above, detector 66 (DET-1) can make one or more single high energy measurements along beam 52 to determine mixture density, gas holdup, etc., while detector 76 (DET-2) can make two or more low energy measurements along beam 54 to determine WLR. MUX 112 can be used to select one of detectors 66 or 76 (DET-1 and DET-2) at a time, wherein longer duration (e.g., ten minutes) or more frequent (e.g., at ten or fifteen minute intervals) measurements can be made along the gas-rich beam 52 for detector 66 (DET-1) to determine rapidly changing gas holdup (i.e., gas fraction) or mixture density, and shorter duration (e.g., five minutes) or less frequent (e.g., at one hour intervals) measurements can be made along the liquid-rich beam 54 for detector 76 (DET-2) to determine the generally slowly changing WLR (in the low GVF near-wall region). The measurements of the two detectors can be alternating and repeated, and the measurement sequence and duration are programmable under the control of CPU 88 or other logic control device. The measurements may be made at a 45 Hz count rate sampling rate or any other suitable sampling rate.

[0040] Figure 6 Another embodiment shown is Figure 5 The embodiment shown differs in that the core window 70 is omitted and the beam 52 is transmitted through a portion 114 of the tube wall 58 (e.g., a metal tube wall). The wall thickness at the portion 114 can be designed to be sufficient to withstand the design pressure, have a sufficiently high energy count rate, and block or filter low energy photons in the beam 52 that are not used for determining the gas fraction or mixture density based on the beam 52.

[0041] Although beams 52 and 54 may be emitted from a shared multi-energy radioactive or x-ray generator source 62, in other embodiments, the beams may be emitted from separate sources. Figure 7 As shown, for example, as described above, the first beam 52 is emitted from the single-energy or multi-energy radioactive or x-ray generator source 62, but the second beam 54 is instead emitted from the multi-energy radioactive or x-ray generator source 116 of the second emitter 14. The second beam 54 is transmitted to the detector 76 through the window 118, the aperture 56, and the window 80. In some cases, the emitter 14 and the detector 16 can be arranged so that the paths of the beams 52 and 54 are parallel within the cross section of the pipe 12. In some cases, Figure 7 One or both of the emitter window 68 and the detector window 72 may be omitted to allow high energy measurements along the diameter of the beam 52 through the metal pipe wall.

[0042] Furthermore, although the gas fraction and WLR of a multiphase fluid can be determined (e.g. Figure 4106 and 108 of FIG. 10B ), but other properties of the multiphase fluid may also or alternatively be determined. For example, for wet gas applications, non-diameter beam and diameter beam measurements may be combined to determine additional fluid properties or to improve flow property measurement accuracy. In some embodiments, diameter beam 52 and non-diameter beam 54, such as described above, may be emitted through a multiphase fluid having a three-phase flow having a concentric gas core and liquid ring structure, such as an annular, annular mist, or mist flow, to determine various fluid properties. These determined fluid properties may include the radius of the gas core ( Figure 4 The two beams 52 and 54 may be emitted from one multi-energy source (e.g., from source 62 through two collimating holes) or from two different sources.

[0043] It should be understood that the fraction of each phase (i.e., gas, water, and oil) in a multiphase flow within a pipe can be measured by a single beam of dual-energy gamma rays. However, this will provide a fraction in the area covered by the majority of the collimated beam, which may not be equal to the expected fraction across the pipe cross section. This is particularly true for core and annulus shaped flow structures, where gas tends to concentrate in the core and liquid in the annulus; through-diameter single beam measurements tend to overestimate the gas fraction.

[0044] However, certain embodiments of the present technology use two beams 52 and 54, which can improve the phase fraction accuracy of core-annular flow structures, such as annular flows, annular mist flows, and mist flows that are common in wet gas flows. In at least some embodiments, beam 52 passes through the diameter of a circular hole 56 of the pipe 12, while the other beam 54 deviates from this diameter to pass through the wall 58 closer to the pipe 12. Using this measurement configuration, two sets of phase fraction equations for annular flows can be derived for calculating the above-mentioned properties. In addition, the liquid (annulus) film thickness and the gas core liquid fraction can be used for multiphase flow modeling, such as for Venturi discharge coefficient calculations, mixture density calculations, and velocity profile predictions. Although such information cannot be extracted from a single beam flow fraction measurement, the measurement technique described herein with beams 52 and 54 can be used to provide the radius of the gas core (at box 142), the gas core liquid fraction (at box 146), the liquid film thickness (at box 148), and the total gas fraction in the core annular shape flow (at box 150).

[0045] An example of such core-annular flow of a multiphase fluid through the bore 56 of the conduit 12 is shown in Figure 81 and 12. The multiphase fluid is generally depicted as having a liquid film 120 surrounding a gas core 122. Although the liquid film 120 is primarily liquid and the gas core 122 is primarily gas, the liquid film 120 may include some gas (e.g., entrained bubbles) and the gas core 122 may include liquid (e.g., entrained droplets). In at least one embodiment, it is assumed that the liquid film 120 is free of gas and the gas core 122 may be a mixture of gas and liquid with different fractions in the cross-sectional area of ​​the core. Two beams 52 and 54 pass through the multiphase fluid from a multi-energy radiation source 62, such as described above. Beam 52 may be a diametric beam passing through the center of the hole 56 (e.g., a venturi throat passing through the pipe 12), and beam 54 may be a non-diametric beam.

[0046] In hole 56, beam 52 passes through region 124 of liquid film 120 and region 126 of gas core 122, while beam 54 passes through region 134 of liquid film 120 and region 136 of gas core 122. Figure 8 As shown, the proportion of the path of beam 54 passing through liquid film 120 is greater than the proportion of the path of beam 52 passing through liquid film 120. In at least some embodiments, the beam passing regions 126 and 136 of gas core 122 and the total area within hole 56 passed by beam 52 (i.e., the sum of regions 124 and 126) and the total area within hole 56 passed by beam 54 (i.e., the sum of regions 134 and 136) can be used to calculate various properties of the analyzed multiphase fluid, such as the radius r of gas core 122, the liquid fraction in gas core 122, the thickness of liquid film 120, WLR, and the phase fraction within hole 56 (hole radius is R, and r≤R).

[0047] For example, the diameter of the beam in the central core through the region 126 can be calculated as:

[0048]

[0049] And the bundle deviation diameter in the core through the bundle area 136 is:

[0050]

[0051] Where h1 is the vertical distance between the center of the pipe and the edge of the diameter bundle 52, h′1 is the vertical distance between the center of the pipe and the upper edge of the offset diameter bundle 54, and h′2 is the distance between the center of the pipe and the lower edge of the bundle 54 (which is collinear with h′1 but is shown in the figure for clarity). Figure 8 ). In addition, R is the radius of the hole 56, r is the radius of the central core (which is initially unknown), and

[0052] It can be assumed that the gas and liquid droplets are uniformly mixed in the central core 122, and the core liquid fraction relative to the core cross-sectional area is And the liquid fraction measured by gamma ray is Γ for diameter beam 52 and non-diameter beam 54 respectively. liq and Γ′ liq Therefore, the measured gas fraction is Γ gas =1-Γ liq and Γ′ gas =1-Γ′ liq . Further:

[0053]

[0054]

[0055] Where a is the beam traversal area for diameter beam 52 (areas 124 and 126) and a' is the beam traversal area for deviation from diameter beam 54 (areas 134 and 136). Note that a and a' are constants that depend on beam geometry. Substituting Equation 1 into Equation 2 and rearranging 2a and 2b to eliminate gives:

[0056]

[0057] Equation 3 has a single unknown variable r and can be solved using an iterative method (such as Newton's method) or any other suitable technique. After solving Equation 3 for the radius r of the gas core, the film thickness can be calculated as:

[0058] t=Rr (4a)

[0059] The liquid fraction in the nucleus can be calculated as:

[0060]

[0061] The gas fraction of the pipe cross section can be calculated as:

[0062]

[0063] The WLR may be determined using dual energy gamma ray measurements performed using a diameter beam (e.g., beam 52) and / or using an offset diameter (near wall) beam (e.g., beam 54) that passes through the localized liquid rich region (which may facilitate greater accuracy in wet gas WLR measurements). For example, the WLR determined by the offset diameter beam is:

[0064]

[0065] The water and oil fractions of the pipe cross section can be calculated as:

[0066] α o =(1-WLR)(1-α g ) (4e)

[0067] α w =WLR(1-α g ) (4f)

[0068] Assume that the left side of Equation 3 is the function f(r), Fig. 9 Flowchart 152 generally illustrates the iterative solution of Equation 3 using the Newton algorithm, where n is the number of iterations, f′(r) is the first derivative of the function f(r), ∈ is the convergence criterion, and α is a relaxation factor defined as α∈(0,1]. After the problem is initialized (block 154), f(r) and f′(r) are calculated (block 156), subsequent approximations are calculated (block 158), and the current approximation is compared to the previous approximation (block 160). If the absolute value of the difference between the current approximation and the previous approximation is below the convergence criterion (block 162), the method ends (block 164). Otherwise, the number of iterations is increased, and blocks 156, 158, 160, and 162 may be repeated until the desired convergence criterion is met. It should be understood that other iterative algorithms may also or alternatively be used to solve Equation 3.

[0069] The foregoing summarizes the features of several embodiments so that those skilled in the art may better understand aspects of the present disclosure. Those skilled in the art will appreciate that they may easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes or to achieve the same advantages as the embodiments described herein. Those skilled in the art will also appreciate that such equivalent structures do not depart from the spirit and scope of the present invention, and that various changes, substitutions, and modifications may be made herein without departing from the spirit and scope of the present invention.

Claims

1. A method comprising: receiving a multiphase fluid within a bore of a conduit; Passing electromagnetic radiation having multiple energy levels through a multiphase fluid in a bore of a pipe, wherein passing electromagnetic radiation through the multiphase fluid in the bore of the pipe comprises: transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the aperture; and transmitting a second beam of electromagnetic radiation through the multiphase fluid along a second beam path within the aperture that is different from the first beam path, wherein the first beam has a length within the aperture along the first beam path that is greater than a length of the second beam within the aperture along the second beam path; detecting, at a first detector, a first beam of electromagnetic radiation transmitted through the multiphase fluid; detecting at a second detector the second beam of electromagnetic radiation transmitted through the multiphase fluid; and determining a gas fraction and a water-to-liquid ratio of the multiphase fluid in the pore, wherein determining the gas fraction is based on the detected first beam of electromagnetic radiation, and determining the water-to-liquid ratio of the multiphase fluid is based on the detected second beam of electromagnetic radiation, wherein determining the gas fraction is based on a first beam of electromagnetic radiation detected at a first energy level among the multiple energy levels, and determining the water-to-liquid ratio of the multiphase fluid is based on a second beam of electromagnetic radiation detected at two or more energy levels among a plurality of energy levels lower than the first energy level.

2. The method according to claim 1, wherein: Transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the aperture includes transmitting the first beam of electromagnetic radiation through the multiphase fluid along a diametric beam path through the aperture.

3. The method according to claim 1, wherein: The multiphase fluid flows through the hole in an annular or annular mist flow state, wherein the heavier fluid in the multiphase fluid forms a liquid film along the inner wall of the pipe defining the hole, and electromagnetic radiation with multiple energy levels passes through the multiphase fluid in the hole of the pipe, including transmitting the first and second beams of electromagnetic radiation, so that the proportion of the second beam path crossing the liquid film along the inner wall in the hole is greater than the proportion of the first beam path crossing the liquid film along the inner wall in the hole.

4. The method according to claim 3, wherein: Transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the aperture includes transmitting the first beam through a gas core of the multiphase fluid within the aperture.

5. The method according to claim 4, wherein: Determining the gas fraction based on the detected first beam of electromagnetic radiation includes determining the gas fraction based on photons of the first beam of electromagnetic radiation having an energy level detected at the first detector, the energy level of the photons of the first beam of electromagnetic radiation being higher than the energy level of photons of the second beam of electromagnetic radiation detected at the second detector on which the determination of the water-to-liquid ratio is based.

6. The method according to claim 5, wherein: Transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the aperture includes emitting the first beam from a radiation source having gamma emissions at discrete energy levels, and the photons of the first beam of electromagnetic radiation on which the determination of the gas fraction is based are gamma ray photons within an upper half of the energy levels of the gamma emissions.

7. The method according to claim 6, wherein: Transmitting a second beam of electromagnetic radiation through the multiphase fluid along a second beam path within the bore includes emitting the second beam from the same radiation source that emitted the first beam.

8. The method according to claim 7, wherein: The photons of the second beam of electromagnetic radiation detected at the second detector on which the determination of the water-to-liquid ratio is based include gamma ray photons within the lower half of the energy level of the gamma emission.

9. The method according to claim 7, wherein: The photons of the second beam of electromagnetic radiation detected at the second detector on which the determination of the water-to-liquid ratio is based include X-ray photons emitted from the radiation source.

10. The method of claim 3, comprising determining a radius of a gas core of the multiphase fluid within the pore.

11. The method of claim 10, comprising determining a liquid fraction of a gas core of a multiphase fluid within the pore.

12. The method of claim 11, comprising determining a gas fraction of the multiphase fluid within the bore of the conduit based on the determined radius of the gas core and the determined liquid fraction of the gas core of the multiphase fluid within the bore.

13. A method comprising: receiving a multiphase fluid within a bore of a conduit; Passing electromagnetic radiation having multiple energy levels through a multiphase fluid in a bore of a pipe, wherein the multiphase fluid flows through the bore in an annular or annular mist-like flow pattern, wherein a heavier fluid in the multiphase fluid forms a liquid film along an inner wall of a pipe defining the bore, and passing electromagnetic radiation having multiple energy levels through the multiphase fluid in the bore of a pipe comprises: transmitting a first beam of electromagnetic radiation through the multiphase fluid along a first beam path through the aperture; and transmitting a second beam of electromagnetic radiation through the multiphase fluid along a second beam path within the aperture that is different from the first beam path, wherein the first beam has a length within the aperture along the first beam path that is greater than a length of the second beam within the aperture along the second beam path; detecting, at a first detector, a first beam of electromagnetic radiation transmitted through the multiphase fluid; detecting at a second detector the second beam of electromagnetic radiation transmitted through the multiphase fluid; and A radius of a gas core of the multiphase fluid within the pore is determined based on the detected first beam of electromagnetic radiation and the detected second beam of electromagnetic radiation.

14. The method of claim 13, comprising determining the liquid fraction of the gas core of the multiphase fluid within the pore.

15. The method of claim 14, comprising determining a gas fraction of the multiphase fluid within the bore of the conduit based on the determined radius of the gas core and the determined liquid fraction of the gas core of the multiphase fluid within the bore.

16. An apparatus comprising: a fluid conduit, the fluid conduit comprising an aperture; and A measurement system positioned to transmit multiple beams of multi-energy-level electromagnetic radiation through a multi-phase fluid received in the hole, the measurement system comprising: at least one radiation source; a first radiation detector positioned to receive a first beam of a plurality of beams emitted through the multiphase fluid along a first beam path from at least one radiation source to the first radiation detector; a second radiation detector positioned to receive a second beam of the plurality of beams emitted through the multiphase fluid along a second beam path from the at least one radiation source to the second radiation detector, wherein the first beam has a length within the aperture along the first beam path that is greater than a length of the second beam within the aperture along the second beam path; and A computer encoded with instructions for calculating a gas fraction of a multiphase fluid based on a first beam at a first energy level among multiple energy levels received by a first radiation detector, and calculating a water-to-liquid ratio of the multiphase fluid based on a second beam at two or more energy levels lower than the first energy level among the multiple energy levels received by a second radiation detector.

17. The device according to claim 16, wherein: The at least one radiation source includes a barium 133 isotope having multiple energy levels that emits x-rays at 32 keV and gamma rays at 81 keV and 356 keV.

18. The device according to claim 16, wherein: The at least one radiation source comprises a multi-energy x-ray generator.

19. The device according to claim 16, wherein: The at least one radiation source, the first radiation detector, and the second radiation detector are located at a same cross-section of a venturi throat of the fluid conduit.

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