RADIATION SOURCE DEVICE HAVING FLUORESCENT MATERIAL FOR SECONDARY PHOTON GENERATION

A radiation source device, a measuring device using the radiation source device, and a method of use of the measuring device are described. The radiation source device has a radiolucent window portion, a shielding portion, a radioactive element, and a fluorescent material. The shielding portion has a window portion cavity and the radiolucent window portion extends across and encompasses the window portion cavity. The radioactive element is positioned within the window portion cavity of the shield portion and emits first photons through the window portion cavity and the radiolucent window portion. The fluorescent material is positioned between the radioactive element and the radiolucent window portion. The fluorescent material receives the first photons from the radioactive element and generates second photons.

BACKGROUND

Description of the Related Art

X- and γ-ray radiation sources are used in a wide variety of applications. For example, they can be used to calibrate equipment, or used in energy-dispersive X-ray fluorescence (EDXRF) analyzers or in multiphase fluid flow analyzers.

A fluorescent X-ray is created when a photon of sufficient energy strikes an atom in the sample, dislodging an electron from one of the atom's inner orbital shells (lower quantum energy states). The atom regains stability, filling the vacancy left in the inner orbital shell with an electron from one of the atom's higher quantum energy orbital shells. The electron drops to the lower energy state by releasing a fluorescent X-ray, and the energy of this fluorescent X-ray (often measured in electron volts, eV) is equal to the specific difference in energy between two quantum states of the dropping electron. The high energy photons (X-rays or γ-rays) are provided by an X-ray or γ-ray source.

Presently, small X- and γ-ray sources often comprise a metal shell (e.g., stainless steel) with an open end into which a holder is inserted. The holder has a front face which carries the radiation source. The radiation source is a radioactive foil or other material. In front of the same foil, to seal off the open end of the metal shell is a radiolucent window, such as beryllium, which is brazed in place to seal it off.

In multiphase fluid analysis, photons interact with the multiphase fluid which absorbs a portion of the photons depending on the multiphase fluid composition. Initial emitted photons are absorbed, or attenuated, by the multiphase fluid and received by a detector. Attenuations are calculated by counting the photons of the specified energy levels impacting a detector after interacting with the multiphase fluid. Flow rates of three phases of the multiphase fluid may be obtained from phase fractions calculated using the attenuations. However, the number of X-rays and γ-rays emitted by a radioactive source in a time interval is not constant. Radioactive decay follows the Poisson statistical model, stating that the number of photons per second with energy E nEaveraged over a time interval t is known with an uncertainty ±√{square root over (nE/t)}. Therefore, attenuations and phase fractions are also affected by statistical uncertainties which can be reduced by increasing the acquisition time t. However, increasing acquisition time, from an operational point of view, reduces a number of tests able to be performed during a predetermined time period.

SUMMARY

In one embodiment, a radiation source device is described. The radiation source device has a radiolucent window portion, a shielding portion, a radioactive material, and a fluorescent material. The shielding portion has a window portion cavity, and the radiolucent window portion extends across and encompasses the window portion cavity. The radioactive material is positioned within the window portion cavity of the shielding portion so as to emit photons through the window portion cavity and the radiolucent window portion. The fluorescent material is positioned between the radioactive element and the radiolucent window portion. For example, if the radioactive material is133Ba, then the fluorescent material receives the photons from the radioactive element and generates photons having an energy level less than 32 keV.

In another embodiment, a measuring device is described. The measuring device is provided with a fluid passage tube, a radiation source device, and a photon detector. The fluid passage tube has a first end, a second end, and a cavity extending between the first end and the second end. The radiation source device has a radioactive material and a fluorescent material and is positioned and able to emit photons across the cavity. The photon detector receives the photons passing across the cavity interacting with a multiphase fluid passing through the fluid passage tube and generates photon signals indicative of the number and energy level of the photons.

In yet another embodiment, a method is described. The method is performed by installing a measuring device in a fluid flow sampled from a downhole formation, generating photon signals via a photon detector indicative of the number and energy level of the photons, and logging data indicative of the photon signals onto a non-transitory computer readable medium. The measuring device has a fluid passage tube having a cavity, and a radiation source device having a radioactive material and fluorescent material positioned and able to emit photons across the cavity. In one embodiment, the measuring device may be a multiphase flow meter. In this embodiment, the fluid passage tube may be a venturi tube having a venturi tube throat, and the multiphase flow meter may have a device for measuring the total flow rate through the venturi tube, such as at least one pressure sensor sensing a differential pressure between a first pressure within the venturi tube throat and a second pressure outside of the venturi tube throat. The photon detector may receive the photons passing across the cavity at the venturi tube throat, for example, and interacting with a multiphase fluid passing through the venturi tube.

DETAILED DESCRIPTION

In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the inventive concept. This description should be read to include one or at least one and the singular also includes the plural unless otherwise stated.

The terminology and phraseology used herein is for descriptive purposes and should not be construed as limiting in scope. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited.

Finally, as used herein any references to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily referring to the same embodiment.

Referring now to the figures, as shown inFIG. 1is an example of a radiation source device10for emitting γ-ray photons, X-ray photons, and fluorescence X-ray photons in a predetermined direction relative to the radiation source device10at several energies depending on the radioisotope contained within the radiation source device10. The radiation source device10may be used to measure phase fractions of a multiphase fluid circulating in hydrocarbon exploitation pipes. The fluorescence X-rays generated by the radiation source device10may shorten the measurement time for a given phase fraction accuracy or may provide higher phase fraction accuracy for a given measurement of time. The multiphase fluid causes attenuations in the γ-ray photons, X-ray photons, and fluorescence X-ray photons emitted by the radiation source device10which may be employed to calculate the composition of the multiphase fluid. As shown inFIG. 1, in one embodiment, the radiation source device10has a radiolucent window portion12configured to allow γ-ray photons, X-ray photons, and fluorescence X-ray photons to be emitted in a predetermined direction, a shielding portion14having a window portion cavity16therein, a radioactive material18positioned within the window portion cavity16of the shielding portion14, and a fluorescent material20positioned between the radioactive material18and the radiolucent window portion12. The radiation source device10may also include a capsule portion22housing the radiolucent window portion12, the shielding portion14, the radioactive material18, and the fluorescent material20. The radiolucent window portion12may extend across and encompass the window portion cavity16. The radioactive material18may emit photons through the window portion cavity16, the fluorescent material20and the radiolucent window portion12. The fluorescent material20may receive the photons from the radioactive material18and generate X-fluorescence photons. In an embodiment where the radioactive material18is133Ba, the X-fluorescence photons generated have an energy level less than 32 keV and between 15 keV and 25 keV. Although the capsule portion22of the radiation source device10is depicted as being cylindrical in shape, it will be understood by one skilled in the art that the radiation source device10may be sized and shaped in any manner such as cubical, pyramidal, spherical, or the like so long as the radiation source device10is capable of emitting photons in a predetermined direction relative to the radiation source device10.

The capsule portion22may be made of a radiopaque material such as stainless steel, nickel-copper alloys, such as Monel® metals, and other suitable radiopaque materials. The capsule portion22may be provided with a first side24, a second side26, an exterior portion28extending between the first side24and the second side26, and an interior portion30extending between the first side24and the second side26opposite the exterior portion28. The first side24may form an open front32of the capsule portion22. The open front32may be provided with an outer rim34with an inner seating rim36. The exterior portion28may form an outer cylindrical surface of the capsule portion22having a diameter of between 3 mm and 10 mm and a height between 3 mm and 10 mm. The interior portion30may form a cylindrical inner surface that defines a generally cylindrical space therein. The inner seating rim36may project inwardly within the interior portion30and may serve to support or contact the radiolucent window portion12. The interior portion30may serve to encapsulate the shielding portion14. The window portion cavity16of the shielding portion14may be sized and shaped to receive the radioactive material18. The shielding portion14with its carried radioactive material18may be inserted into the capsule portion22and seated against the radiolucent window portion12such that radiation emitted from the radioactive material18emanates from the radiolucent window portion12, but not from other directions of the radiation source device10. The shielding portion14may be affixed to the capsule portion22, e.g., by fusion welding. In one embodiment, the shielding portion14is affixed to the capsule portion22via a cap38fitting within a portion of the interior portion30of the capsule portion22, opposite the radiolucent window portion12, and welded to the capsule portion22.

The radiolucent window portion12may be provided with a first side40and a second side42opposite the first side40. The radiolucent window portion12may be sized and shaped such that the first side40of the radiolucent window portion12may be positioned against the inner seating rim36within the interior portion30of the capsule portion22. The radiolucent window portion12may be affixed in place, e.g., by brazing, adhesive, or other suitable mechanisms. The radiolucent window portion12may be formed of radiolucent material such as beryllium or fiber reinforced polymers, for example.

The shielding portion14may be provided with a first side44and a second side46opposite the first side44, with the window portion cavity16defined within the first side44of the shielding portion14. The shielding portion14may be sized and shaped to fit inside the interior portion30of the capsule portion22. The shielding portion14may be positioned within the interior portion30such that the first side44of the shielding portion14may be adjacent to the second side42of the radiolucent window portion12and so that the radioactive material18seated within the window portion cavity16may be adjacent to the radiolucent window portion12. The shielding portion14may be constructed from a radiopaque material, such as stainless steel, zirconium, molybdenum, palladium, or silver, nickel-copper alloys, such as Monel®, and the like.

The radioactive material18may be configured to fit within the window portion cavity16of the shielding portion14and adjacent to the radiolucent window portion12. In one embodiment, the radioactive material18is made of a133Ba-based ceramic matrix to generate photons having energy levels of 32 keV and 81 keV, where the 32 keV energy level is made by 31 keV and 35 keV X-rays naturally emitted by the133Ba radioisotope. The radioactive material18may also be formed from109Cd,153Gd,139Ce,152Eu, or other suitable radioactive materials. In some embodiments, the radioactive material18may be formed from radioactive materials having a single γ-ray emissions with energy between 40 and 100 keV, such as241Am, for example and in this embodiment two different fluorescent materials20can be used to generate two different levels of X-ray fluorescent photons to provide three different levels of photon emissions.

The fluorescent material20is positioned between the radioactive material18and the radiolucent window portion12. The fluorescent material20may be composed of a metallic material and may be selected from a group consisting of zirconium, molybdenum, palladium, and silver. The fluorescent material20may have a thickness in a range from 40 μm to 200 μm. In one embodiment, as shown inFIG. 2, the fluorescent material20may be implemented as a coating applied to the radioactive material18or by insertion of a metal foil between the radioactive material18and radiolucent window portion12. In another embodiment, as shown inFIG. 3, the fluorescent material20may be implemented as a coating applied to the radiolucent window portion12. In yet another embodiment, as shown inFIG. 4, the fluorescent material20may be implemented as an independent unit separate from and not attached to the radioactive material18and the radiolucent window portion12and positioned between the radioactive material18and the radiolucent window portion12. In combination with the radioactive material18, the fluorescent material20may produce a low energy photon beam of between 15 keV and 25 keV which may be detected and interpreted to reduce the statistical uncertainties discussed above.

When assembled within the radiation source device10the photons with several energy levels emitted from the radioactive material18are received by the fluorescent material20and cause the fluorescent material20to generate extra photons. In one embodiment, where the radioactive material18is133Ba, the extra (or X-fluorescence) photons generated by the fluorescent material20have an energy level less than 32 keV and may be within a range between 15 keV and 25 keV.

Referring now toFIG. 2, therein shown is an embodiment, as referenced above, of the radiation source device10in which the fluorescent material20is a coating applied to the radioactive material18. The fluorescent material20may be applied and attached to the radioactive material18as a foil or by vapor deposition of a thin coating onto the radioactive material18. For example, the fluorescent material20may be a thin metallic coating applied by vapor deposition. The thin metallic coating may be chosen from the group consisting of zirconium, molybdenum, palladium and silver, for instance. Although the fluorescent material20is described as being deposited as a foil or by vapor deposition, it will be understood by one skilled in the art that the fluorescent material20may be applied by other suitable methods.

Referring now toFIG. 3, therein shown is an embodiment, as referenced above, of the radiation source device10in which the fluorescent material20is a coating applied to the radiolucent window portion12. The fluorescent material20may be applied, as described above, as a foil or by vapor deposition of a thin coating onto the radiolucent window portion12, or may be applied by any other suitable methods. As shown inFIG. 3, the fluorescent material20may be applied after the radiolucent window portion12has been inserted into the capsule portion22, thereby applying a portion of the fluorescent material20to the first side24of the capsule portion22. However, it will be understood by one skilled in the art that the fluorescent material20may be applied to the radiolucent window portion12prior to insertion into the capsule portion22.

Referring now toFIG. 4, shown therein is an embodiment, as referenced above, of the radiation source device10in which the fluorescent material20is an independent unit separate from and not attached to the radioactive material18and the radiolucent window portion12. As shown inFIG. 4, the fluorescent material20is positioned between the radioactive material18and the radiolucent window portion12without being applied as a coating to either the radioactive material18or the radiolucent window portion12. In one embodiment, the fluorescent material20may be positioned between the radiolucent window portion12and the radioactive material18. In another embodiment, the fluorescent material20may be positioned within a void defined by the radioactive material18and the radiolucent window portion12. In another embodiment, the fluorescent material20may be positioned adjacent to an opposing side of the radiolucent window portion12such that the radiolucent window portion12is positioned against the radioactive material18and the fluorescent material20is positioned on a side of the radiolucent window portion12opposite the radioactive material18. In this embodiment, for instance, the fluorescent material20may be initially placed against the inner seating rim36of the capsule portion22with the radiolucent window portion12being inserted into the capsule portion22after the fluorescent material20has been positioned and to secure the fluorescent material20in place.

The radiation source device10may be used in applications such as, for example, measuring devices, multiphase flow meters, phase fraction measuring devices, equipment calibration operations, thickness and density devices, and other applications. Although a few applications are mentioned or discussed at length in the present disclosure, one skilled in the art will understand that the radiation source device10may be suitable for use in applications not specifically referenced.

The radiation source device10may be used within a measuring device, in one embodiment characterized as a phase fraction measuring device, a multiphase flow meter, or other measurement devices. In general, the measuring device, when characterized as a phase fraction measuring device, may be provided with a fluid passage tube having a first end, a second end, and a cavity extending between the first end and the second end, the radiation source device10capable of generating first photons from the radioactive material18and second photons from the fluorescent material20, a photon detector, and a computer. The photon detector may receive the first and second photons passing across the cavity and generate photon signals indicative of a number and energy levels of the first and second photons. The computer may receive the photon signals and calculate the phase fractions of the multiphase fluid with information obtained from the photon signals.

Through photons at (at least) two energy levels, (at least) three phase fractions can be calculated, thus indicating the fluid composition. In order to measure flow rates of each phase of the multiphase fluid, the total flow rate should be known. Thus, when the measuring device50includes components to measure the total flow rate, the measuring device50can be characterized as a multiphase flow meter. Referring now toFIG. 5-1, shown therein is one embodiment of the measuring device50characterized as a multiphase flow meter50. The multiphase flow meter50is provided with a venturi tube52, the radiation source device10positioned and configured to emit photons through the venturi tube52which interact with the multiphase fluid traveling through the venturi tube52, a first pressure sensor56positioned to sense a first pressure within the venturi tube52, a second pressure sensor58positioned to sense a second pressure within the venturi tube52, and a photon detector60receiving photons passing across the venturi tube52. The first pressure sensor56, the second pressure sensor58, and the photon detector60may be coupled to a computer system62having a processor such that signals generated by the first pressure sensor56, the second pressure sensor58, and the photon detector60may be transmitted to the computer system62for analysis. Although the multiphase flow meter50is shown having a venturi tube52, other embodiments of multiphase flow meter may not use venturi tubes but rather cause a multiphase fluid to pass through a pipe or other container in order to be analyzed.

The venturi tube52is provided with a first end64, a second end66, and a cavity68extending between the first end64and the second end66. The first end64and the second end66may be configured to connect to piping through which a fluid flow sampled from a downhole formation is passed. For example, the first and second ends64and66may be threaded, flanged and configured to accept bolts, or may have clamps configured to connect to piping, such that the venturi tube52may be installed in the fluid flow and allow the sample to pass through the venturi tube52. The venturi tube52has a protrusion72adjacent to an inner surface70to define a venturi tube throat74. The venturi tube throat74causes a pressure drop when a multiphase fluid, such as a combination of liquid and gas, flows through the venturi tube52and thereby through the venturi tube throat74. The venturi tube52may have a ratio between an interior diameter of the venturi tube throat74and the interior diameter of the venturi tube52of 0.5. The venturi tube52may be constructed as a tube of 38 mm, 80 mm, 130 mm, or any other suitable diameter. In one embodiment, the venturi tube52may be constructed of radiopaque material, having window portions constructed from radiolucent materials, such that the radiation source device10may be positioned to emit photons through a first window portion at the venturi tube throat74so that the photons pass through the first window portion and a second window portion, opposite and facing the first window portion relative to the venturi tube52, to be received by the photon detector60.

In one embodiment, the radiation source device10may be positioned and configured to emit photons across the cavity68at the venturi tube throat74. However, the radiation source device10may be positioned at varying places along the venturi tube52, including outside of the venturi tube throat74. In one embodiment, where the radioactive material18is133Ba, the photons may have energy levels greater than or equal to 32 keV and extra photons generated by the fluorescent material20may have an energy level less than 32 keV. As shown inFIG. 5, the radiation source device10may be positioned within the venturi tube52in a recess adjacent to the venturi tube throat74.

The first pressure sensor56may sense a first pressure within the venturi tube throat74and generate first pressure signals indicative of the first pressure. The first pressure sensor56may transmit the first pressure signals to the computer system62for use in determining the multiphase flow of a fluid traveling through the venturi tube52. The first pressure sensor56may be implemented as any type of pressure sensor capable of sensing pressure within the venturi tube throat74and transmitting the first pressure signals indicative of that pressure to the computer system62.

The second pressure sensor58may sense a second pressure outside of the venturi tube throat74and generate second pressure signals indicative of the second pressure. The second pressure sensor58may transmit the second pressure signals to the computer system62for use in determining the multiphase flow of the fluid traveling through the venturi tube52. The second pressure sensor58may be implemented as any suitable pressure sensor capable of sensing pressure within venturi tube52outside of the venturi tube throat74and transmitting the second pressure signals indicative of that pressure to the computer system62.

In one embodiment, as shown inFIG. 5-2, the first and second pressure sensors56and58may be implemented as a differential pressure sensor76. In this embodiment, the differential pressure sensor76may be connected to the venturi tube52adjacent to a first pressure measurement opening78-1and a second pressure measurement opening78-2and may be configured to measure a pressure difference between the first and second pressure measurement openings78-1and78-2. The first pressure measurement opening78-1is positioned at the venturi tube throat74and the second pressure measurement opening78-2is positioned prior to or upstream of the venturi tube throat74. In relation toFIG. 5-1, the first pressure measurement opening78-1may substitute and be located at the position of the first pressure sensor56while the second pressure measurement opening78-2may substitute and be located at the position of the second pressure sensor58. The first and second pressure measurement openings78-1and78-2may be connected to the differential pressure sensor76such that the differential pressure sensor may detect a differential pressure, indicative of the change in pressure between the first pressure measurement opening78-1and the second pressure measurement opening78-2, within the fluid traveling through the venturi tube52located at or near the venturi tube throat74and generate at least one pressure signal indicative of the differential pressure.

Although shown inFIGS. 5-1 and 5-2as being provided with a venturi tube52and a venturi tube throat74, some embodiments of a phase fraction measuring device or a multiphase flow meter may not be provided with a venturi tube52or a venturi tube throat74. For example, in one embodiment a measuring device, characterized as a phase fraction measuring device, may be provided with a fluid passage tube, such as a pipe or other container, configured to receive and allow passage of a multiphase fluid to be analyzed by the radiation source device10, the photon detector60, and the computer system62. Further, a measuring device, can be characterized as a multiphase flow meter and in such case the multiphase flow meter has a device to measuring the flow of the multiphase fluid, such as the differential pressure sensor76inFIG. 5-2, or the first and second pressure sensors56and58inFIG. 5-1, in addition to the fluid passage tube, the radiation source device10, the photon detector60, and the computer system62. In one embodiment, the multiphase flow meter may be provided with a coriolis or other flow meter rather than the differential pressure sensor76, to sense the flow rate of the multiphase fluid through the fluid passage tube. Although the phase fraction measuring device may be described as employing venturi tubes, pipes, or containers, and the multiphase flow meter may additionally be described as employing pressure sensors, differential pressure sensors, or coriolis flow meters, it will be understood by one skilled in the art that the multiphase flow meter and the phase fraction measuring device may be constructed in a number of different ways while remaining within the scope of the present disclosure.

The photon detector60may receive the photons passing across the cavity68at the venturi tube throat74and generate photon signals indicative of the number and energy level of the photons. The photon detector60may transmit the photon signals to the computer system62for use in determining the multiphase flow of the fluid traveling through the venturi tube52. The photon detector60may be positioned opposite the radiation source device10and may be at least partially supported by a recess within the venturi tube52. The photon detector60may be implemented as any suitable photon detector capable of generating electrical signals indicative of photons that are received from the radiation source device10. For example, the photon detector60can be a scintillator detector, capable of detecting γ-rays and X-rays. The scintillator may be composed of YAP(Ce), Nal(TI), or CeBr3, for example. The detector may be completed with a photomultiplier tube and a power supply.

The computer system62may be provided with a processor, a non-transitory computer readable medium, processor executable instructions stored on the non-transitory computer readable medium, an input device, an output device, and a communications device. The processor may be implemented as a single processor or multiple processors working together or independently to execute the processor executable instructions. The processor is coupled to the non-transitory computer readable medium which may be implemented as RAM, ROM, flash memory or the like, and may take the form of a magnetic device, optical device, or the like. The input device may transmit data to the processor and may be implemented as a keyboard, a mouse, a touch-screen, a camera, a cellular phone, a tablet, a smart phone, a PDA, a microphone, a network adapter, cable adapter such as a USB port, a scanner, and combinations thereof. The output device transmits information from the processor to a user and may be implemented as a server, a computer monitor, a cell phone, a tablet, a speaker, a website, a PDA, a fax, a printer, a projector, a laptop monitor, and combinations thereof. The network communications device may facilitate communications between a network and the processor. Stored on the non-transitory computer readable medium, the processor executable instructions, when executed by the processor, may cause the processor to receive the at least one pressure signal and photon signals from the first and second pressure sensors56and58and the photon detector60and calculate a composition of the multiphase fluid traveling through the venturi tube52. The composition of the multiphase fluid, i.e. the phase fractions, may be given by the photon signals from the photon detector60. The flow rate of each individual phase of the multiphase fluid may be calculated using a pressure difference between the first pressure signals and the second pressure signals, generating a total flow rate, and the photon signals. In the embodiment having the differential pressure sensor76, the flow rate of the individual phases of the multiphase fluid may be calculated using the at least one pressure signal indicative of the differential pressure and the photon signal from the photon detector.

A method for using a measuring device50, generally, may include installing the phase fraction measuring device50in a fluid flow sampled from a downhole formation. The phase fraction measuring device50may have the fluid passage tube52with a cavity, a radiation source device10with the radioactive material18and the fluorescent material20. The radioactive material18generates first photons and the fluorescent material20receives the first photons from the radioactive material and generates second photons. The radiation source device10is positioned and configured to emit the first and second photons across the cavity to interact with a multiphase fluid passing through the fluid passage tube. The photon detector60may receive the photons passing across the cavity and interacting with the multiphase fluid passing through the fluid passage tube52. After installation of the radiation source device10, photon signals may be generated via the photon detector60indicative of a number and energy levels of the first and second photons. Data indicative of the photon signal may be logged onto a non-transitory computer readable medium.

Referring now toFIG. 6, shown therein is one embodiment of a method for installing and using the measuring device50ofFIG. 5. The measuring device50may be installed at block100. The measuring device50may be installed in a fluid flow sampled from a downhole formation. For example, the measuring device50may be installed between two sections of pipe through which a fluid flow sampled from a downhole formation is directed. The measuring device50may be connected using threaded connections at the first and second ends64and66or any other suitable mechanism to enable passage of the fluid flow through the measuring device50. Once installed, the measuring device50may generate first pressure signals102via the first pressure sensor56indicative of a first pressure of the multiphase fluid passing through the venturi tube52at the venturi tube throat74, at block104. Block104may also represent at least one pressure signal102indicative of the differential pressure generated by the differential pressure sensor76, as shown inFIG. 5-2. The measuring device50may also generate second pressure signals106via the second pressure sensor58indicative of the second pressure of the multiphase fluid passing through the venturi tube52prior to or after the venturi tube throat74. The measuring device50may generate photon signals110at block112via the photon detector60. The photon signals110are indicative of the number and the energy levels of the photons emitted by the radiation source device10passing through the venturi tube52and the multiphase fluid at the venturi tube throat74.

At block114, the measuring device50logs data indicative of the first pressure signal, the second pressure signal, and the photon signal102,106, and110onto the non-transitory computer readable medium of the computer system62. As will be described in further detail below in relation toFIG. 7, the computer system62may calculate the single phase flow rates of the multiphase fluid traveling through the venturi tube52at block116. The computer system62may calculate the total flow rate of the multiphase fluid by calculating a pressure difference118between the first pressure signals102and the second pressure signals106generating a total flow rate for the multiphase fluid. The computer system62may then calculate the single phase flow rates120within the multiphase fluid from the photon signals110and the pressure difference118. The pressure difference118may also be taken from the differential pressure of the at least one pressure signal102generated by the differential pressure sensor76.

Installing the measuring device50may further involve calibrating the measuring device50. Calculating the phase fraction of the multiphase fluid may be based on Beer-Lambert law using equation 1:

In equation 1, nEis a number of photons per second with energy E averaged over a time interval t, nE,0is a number of photons per second with energy E detected when the venturi tube52is empty, λE,iare linear attenuation coefficients, in cm−1, for the energy E for phases (water, oil, gas) of the multiphase fluid, d is a photon beam propagation distance through the multiphase fluid. A calibration process may be used to determine the linear attenuation coefficients λE,i. The calibration process may be performed prior to or after taking samples from the fluid flow sampled from the downhole formation.

The calibration process may be performed by filling the venturi tube52with 100% water, generating the photon signal110for water. The venturi tube52may then be filled with 100% oil and the phase fraction measuring device50may then generate the photon signal110for oil. The venturi tube52may then be filled with 100% gas and the measuring device50may then generate the photon signal110for gas. The computer system62may then be used to generate a graph, represented byFIG. 7, using the data indicative of the photon signals102for the water, oil, and gas, respectively.

The phase fractions120of the multiphase fluid traveling through the phase fraction measuring device50may be calculated using the photon signals110. The low energy fluorescent emission below 25 keV, in addition to the natural emissions of 32 keV and 81 keV, in the embodiment using133Ba, enable an additional low energy photon beam. The additional low energy photon beam may be used in conjunction with the natural emissions to calculate the phase fractions of the multiphase fluid with a shorter measurement time for a predetermined accuracy or with increased accuracy for the same measurement time. Entering the three energy levels (<25 keV, 32 keV, and 81 keV for133Ba), into equation 1 may generate equation 2:

which may be solved to calculate the phase fractions. In equation 2, λExfluo,mixrepresents measured linear coefficients at the energy level Exfluobelow 25 keV for the mixture, λ32,mixrepresents measured linear coefficients at the low energy level 32 keV, λ81,mixrepresents measured linear coefficients at the high energy 81 keV in the embodiment using133Ba, and αirepresents the phase fractions, with i representing either water, oil, or gas. By considering the Beer-Lambert law of equation 1 for three energy levels, the linear system becomes over-determined for three unknowns (αi) and four available equations. The computer system62may solve equation 2 using a weighted linear least squares method to give a unique solution, for example.

As shown inFIG. 7, the computer system62may calculate the linear attenuation coefficients indicative of the attenuation of the γ- and X-rays passing through the water, oil, and gas. The graph, representative of the linear attenuation coefficients, has an x axis λLEplotting points indicative of the linear attenuation coefficient values at low energy and a y axis λHEplotting points indicative of linear attenuation coefficient values at high energy. A linear attenuation coefficient for water122indicative of the photon signals110passing through 100% water, a linear attenuation coefficient for oil124indicative of the photon signals110passing through 100% oil, and a linear attenuation coefficient for gas126indicative of the photon signals110passing through 100% gas are calculated by the computer system62and may be plotted on the graph ofFIG. 7forming a first attenuation triangle132with an area138. The larger the area138of the triangle132, the smaller the phase fraction uncertainties for the same acquisition time, or conversely, shorter acquisition time for the same phase fraction accuracy. This triangle has a linear attenuation coefficient for water134indicative of the photon signals110passing through 100% water, a linear coefficient for oil136indicative of the photon signals110passing through 100% oil, and the linear coefficient for gas126indicative of the photon signals110passing through 100% gas. The attenuation triangle132forms an area138. The attenuation triangle132plots attenuation points for [32; 81] keV, where 32 keV is the low energy and 81 keV is the high energy, in the embodiment using133Ba. The area138corresponds to a scenario with photons emitted by133Ba without X-fluorescence and the possible phase fraction combinations are distributed across the area138. A second attenuation triangle128is representative of plots of attenuations points for [Exfluo; 81] keV where Exfluois the low energy, indicative of the fluorescence X-rays generated by the fluorescence material of the radiation source device10, where Exfluois below 25 keV, and 81 keV is the high energy, in the embodiment using133Ba. The area130corresponds to a scenario with photons emitted by133Ba with X-fluorescence and the possible phase fraction combinations are distributed across the area130, larger than138.

For example, let M be the attenuation matrix. A system of equation 2 has a unique solution when det(M)≠0, e.g., rows are linearly independent. It may be noted that the attenuation triangles areas130and138, ofFIG. 7, correspond to det(M). By assuming a perfect calibration, statistical uncertainties solely affect the left-hand column matrix. In an inversion process for solving the system, a larger det(M) may correlate to a smaller uncertainty amplification.

The same technique described above can be used with different couples of low and high energies by choosing different radioisotopes from133Ba, such as109Cd,153Gd,139Ce, and152Eu, for example. In another example, radioisotopes emitting a single y-ray with energy between 40 keV and 100 keV can be used, such as241Am. In order to generate two extra energies for the attenuation matrix through X-ray fluorescence, the fluorescent material may be formed by a two-layer assembly of sheets or by an alloy of two metals, such that each of the metals within the alloy produce a differing fluorescent energy.

Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods, and uses, such as are within the scope of the appended claims.