阅读说明：本技术 水下流量计射线收发体系及扣除计量方法 (Ray receiving and transmitting system of underwater flowmeter and deduction metering method ) 是由 潘艳芝 王镇岗 文鹏荣 于 2021-10-29 设计创作，主要内容包括：本发明首先公开了一种水下流量计射线收发体系,包括流量计本体,该流量计本体上贯穿有流体计量通道、发射窗和探取窗,其中发射窗和探取窗分别与流体计量通道接通,发射窗和探取窗内均设有钛合金隔离座和铍垫。通过相对容易加工成型的钛合金封隔流体计量通道,采用钛合金和铍垫组合承压,采用铍垫减少对伽马射线的吸收；从而解决由于材料(陶瓷)问题导致的加工不便、寿命不长、可靠性不高等问题。本发明同时公开了一种水下流量计的扣除计量方法,其在算法中将康普顿散射效应引起的伽马计数率失真部分扣除,再计算三相混合流中各相的含量,以提高油气水三相含量的计量准确性。(The invention firstly discloses a ray transceiving system of an underwater flowmeter, which comprises a flowmeter body, wherein a fluid metering channel, a transmitting window and a probing window penetrate through the flowmeter body, the transmitting window and the probing window are respectively communicated with the fluid metering channel, and a titanium alloy isolation seat and a beryllium pad are respectively arranged in the transmitting window and the probing window. The titanium alloy which is relatively easy to machine and form is used for sealing the fluid metering channel, the titanium alloy and the beryllium pad are used for bearing pressure in a combined mode, and the beryllium pad is used for reducing the absorption of gamma rays; thereby solving the problems of inconvenient processing, short service life, low reliability and the like caused by the problem of materials (ceramics). The invention also discloses a deduction metering method of the underwater flowmeter, which is characterized in that the gamma counting rate distortion part caused by the Compton scattering effect is deducted in the algorithm, and the content of each phase in the three-phase mixed flow is calculated, so that the metering accuracy of the oil-gas-water three-phase content is improved.)

1. A ray receiving and dispatching system of an underwater flowmeter comprises a flowmeter body (10), wherein a fluid metering channel penetrates through the flowmeter body (10), a transmitting window and a detecting window which are respectively arranged on two sides of the fluid metering channel are arranged on the flowmeter body (10), the inner end of the transmitting window is opposite to the inner end of the detecting window and is respectively communicated with the fluid metering channel, a ray transmitting module is arranged in the transmitting window, a ray detecting module is arranged in the detecting window, the ray transmitting module transmits rays and passes through the fluid metering channel, and the ray detecting module detects and receives the rays passing through the fluid metering channel;

the ray emission module comprises a radiation source group (21), a collimator (22) and a first isolation seat (24) which are sequentially arranged, the first isolation seat (24) is positioned at the inner end of the emission window, the fluid metering channel and the emission window are separated and sealed by the first isolation seat (24), and the end surface of the inner end of the first isolation seat (24) is flush with and adapted to the inner wall of the fluid metering channel;

the ray exploring module comprises a probe assembly (31), a compression ring (32) and a second isolation seat (34) which are sequentially arranged, the second isolation seat (34) is positioned at the inner end of the exploring window, the fluid metering channel and the exploring window are separated and sealed by the second isolation seat (34), and the end surface of the inner end of the second isolation seat (34) is flush with and adapted to the inner wall of the fluid metering channel;

the method is characterized in that:

a first beryllium pad (23) is arranged between the collimator (22) and the first isolation seat (24), and the first isolation seat (24) is made of a titanium alloy material;

a second beryllium pad (33) is arranged between the compression ring (32) and the second isolation seat (34), and the second isolation seat (34) is made of a titanium alloy material.

2. The underwater flow meter ray transceiving system of claim 1, wherein: a first embedding counter bore is arranged on the surface of the first isolation seat (24) facing the collimator (22), a first ejector block (221) matched with the first embedding counter bore is arranged on the collimator (22), a beryllium piece embedding opening is arranged on the first ejector block (221), the beryllium piece embedding opening faces the hole bottom of the first embedding counter bore, the first beryllium pad (23) is embedded in the beryllium piece embedding opening and matched with the beryllium piece embedding opening, the first ejector block (221) extends into the first embedding counter bore, the extending end of the first ejector block (221) is tightly abutted against the hole bottom of the first embedding counter bore, the first beryllium pad (23) is tightly abutted against the hole bottom of the first embedding counter bore, an alignment hole (22 a) penetrates through the collimator (22), one end of the straight hole (22 a) is large in aperture and the other end of the straight hole (22 a) is small in aperture, and the small hole end of the alignment hole (22 a) faces the radioactive source group (21), the large hole end of the collimation hole (22 a) is communicated with the beryllium sheet embedding opening and faces to the first beryllium pad (23).

3. The underwater flow meter ray transceiving architecture of claim 2, wherein: and a second embedded counter bore is formed in the surface, facing the compression ring (32), of the second isolation seat (34), the second beryllium pad (33) is embedded in the second embedded counter bore and matched with the second beryllium pad, and the compression ring (32) compresses the second beryllium pad (33) and the second isolation seat (34) simultaneously.

4. The subsea flowmeter ray transceiver system of claim 3, wherein: the second embedded counter bore comprises a round hole section and a round table hole section, wherein the round hole section is close to the fluid metering channel, the circular truncated cone hole section faces the compression ring (32), the second beryllium pad (33) is embedded in the circular hole section, a circle of pressing flanges (321) are arranged on the end face, facing the second embedded counter bore, of the pressing ring (32), the pressing flange (321) is arranged close to the inner ring of the pressing ring (32), the inner ring of the pressing flange (321) is flush with the inner ring of the pressing ring (32), the pressing flange (321) is embedded in the circular truncated cone hole section, the outer ring of the pressing flange (321) is matched with the hole wall of the circular truncated cone hole section, the end face of the embedded end of the pressing flange (321) presses the second beryllium pad (33), the compression ring (32) and the outer ring of the compression flange (321) compress the second isolation seat (34).

5. The subsea flowmeter ray transceiver system of claim 1 or 2, wherein: the thickness of the second beryllium pad (33) is greater than the thickness of the first beryllium pad (23).

6. A deduction metering method of an underwater flowmeter is characterized by comprising the following steps:

firstly, setting up the ray transceiving system of the underwater flowmeter according to any one of claims 1 to 5, penetrating the fluid metering channel by using any two energy levels of the radiation source group (21), and acquiring gamma count rates of corresponding first and second energy levels by the probe assembly (31)N；

Step two, respectively measuring the first and second empty pipe counting rates of two groups of energy levels under the condition that the fluid metering channel is emptied、；

Under the metering state, oil-gas-water three-phase mixed flow passes through the fluid metering channel, and the first and second measuring counting rates of two groups of energy levels are respectively measured、；

Step three, defining a first empty pipe deduction value on an empty pipe gamma absorption energy spectrumAnd a second empty pipe deduction value(ii) a Defining a first measurement subtraction value on a measured gamma absorption spectrumAnd a second measurement subtraction value；

Respectively counting the first empty pipeSecond empty tube count rateFirst measured count rateSecond measured count rateDeducting and correcting to obtain the first empty pipe deduction counting rateThe second empty tube deducts the counting rateFirst measurement deduct count rateSecond measurement deducted count rate；

；

；

；

；

Step four, calculating the gas phase content in the multiphase mixed flow according to the following formulaOil phase contentWater phase content of；

；

Wherein:

dthe distance of the gamma ray passing through the fluid metering channel is measured;

an absorption coefficient of gamma rays at a first energy level for the gas phase;

is the absorption coefficient of oil relative to gamma rays at a first energy level;

is the absorption coefficient of water relative to gamma rays at a first energy level;

is the absorption coefficient of the gas phase to gamma rays at the second energy level;

is the absorption coefficient of the oil relative to gamma rays at a second energy level;

is the absorption coefficient of water relative to gamma rays at a second energy level.

7. The subtractive metering method of a subsea flowmeter of claim 6, wherein: in the third step, the first empty pipe deduction valueSecond empty pipe deduction valueFirst measurement deduction valueThe second measurement deduction valueAre calculated according to the following method:

defining deduction ranges corresponding to a first energy level and a second energy level on the empty tube gamma absorption energy spectrum and the measured gamma absorption energy spectrum respectively, wherein the deduction ranges comprise two deduction lineages vertical to the abscissa axis of the gamma absorption energy spectrum, the two deduction lineages are located on two sides of the peak top value of the corresponding energy level, and intersection points of the two deduction lineages and the abscissa axis of the corresponding gamma absorption energy spectrum are respectively intersection points、The intersection points of the two deduction lineation lines and the corresponding gamma absorption energy spectrum spectral lines are respectively、；

i=0，x；

j=1，2；

The first empty pipe deduction valueDefined to correspond to a first energy level in the gamma absorption spectrum of the blank tube，，，The trapezoidal or rectangular area formed by the four points;

the second empty pipe deduction valueDefined for corresponding to a second energy level in the gamma absorption spectrum of the empty tube，，，The trapezoidal or rectangular area formed by the four points;

the first measurement deduction valueFor measuring gamma absorptionCharacterised by the energy absorption spectrum corresponding to the first energy level，，，The trapezoidal or rectangular area formed by the four points;

the second measurement deduction valueDefined for corresponding to a second energy level in the measured gamma absorption spectrum，，，The trapezoidal or rectangular area is enclosed by the four points.

Technical Field

The invention relates to equipment and a method for marine oil engineering, in particular to underwater multiphase flow metering equipment for marine oil engineering.

Background

In the Chinese patent application (publication number: CN 106706047A; CN 106768120A) filed in 2017, the applicant proposes to adopt ceramic materials (a first ceramic sealing gasket and a second ceramic sealing gasket) to seal off a fluid metering channel so as to reduce the absorption of gamma rays and improve the measurement accuracy of oil, gas and water three phases. But the following problems were found in the production and application in the following years: although the ceramic material has little resistance to gamma rays, the ceramic material has poor ductility, is difficult to process into a special-shaped structure, is easy to break, and cannot meet the requirements of 20-year service life and reliability of products.

Based on the reasons, the search for a replacement scheme of a ceramic material is particularly urgent, and the conventional packing material comprises steel and PEEK; the steel material has higher density, and can absorb gamma rays too much, so that the measurement cannot be carried out; and the strength of PEEK is not enough and can not be matched with a metal sealing ring. The titanium alloy has high strength, is relatively easy to machine and form, and has density far lower than that of common steel, so that the titanium alloy can be an alternative scheme. However, when the thickness of the titanium alloy material is too large, more gamma rays can still be absorbed, which is unfavorable for improving the accuracy of oil-gas-water three-phase measurement; and heavy components in the titanium alloy year are more scattered to gamma rays, and compared with a common ceramic window or PEEK window, the gamma ray energy spectrum has obvious Compton effect (see Chinese patent applications with publication numbers of CN107436165A and CN 107331429A), and the gamma rays with high energy levelγ _h After Compton scattering of titanium alloy, the part is reduced to energy levelγ _l Possibly in combination with low-level radiation emitted by the gamma source itselfγ _l The "coincidence" causes a distortion in the count rate obtained by the gamma probe, which deepens as the thickness of the titanium alloy penetrated by the gamma rays increases. The packing structure is required to be further adjusted and optimized in structure and material, and the thickness of the titanium alloy is reduced on the premise of ensuring the compressive strength; and a solution to the effect of compton scattering on the probe count rate is sought.

Disclosure of Invention

In view of the above, the present invention first provides a ray transceiving system for an underwater flowmeter, which uses a new material/material combination and structural design to ensure compressive strength and reduce absorption of gamma rays.

The technical scheme is as follows:

a ray receiving and dispatching system of an underwater flowmeter comprises a flowmeter body, wherein a fluid metering channel penetrates through the flowmeter body, a transmitting window and a probing window which are respectively arranged on two sides of the fluid metering channel are arranged on the flowmeter body, the inner end of the transmitting window is opposite to the inner end of the probing window and is respectively communicated with the fluid metering channel, a ray transmitting module is arranged in the transmitting window, a ray probing module is arranged in the probing window, the ray transmitting module transmits rays and passes through the fluid metering channel, and the ray probing module probes and receives the rays passing through the fluid metering channel;

the ray emission module comprises a radiation source group, a collimator and a first isolation seat which are sequentially arranged, the first isolation seat is positioned at the inner end of the emission window, the first isolation seat separates and seals the fluid metering channel and the emission window, and the end surface of the inner end of the first isolation seat is flush with and adapted to the inner wall of the fluid metering channel;

the ray acquisition module comprises a probe assembly, a compression ring and a second isolation seat which are sequentially arranged, the second isolation seat is positioned at the inner end of the acquisition window, the second isolation seat separates and seals the fluid metering channel and the acquisition window, and the end surface of the inner end of the second isolation seat is flush with and adapted to the inner wall of the fluid metering channel;

the key points are as follows:

a first beryllium pad is arranged between the collimator and the first isolation seat, and the first isolation seat is made of a titanium alloy material;

and a second beryllium pad is arranged between the compression ring and the second isolation seat, and the second isolation seat is made of a titanium alloy material.

The technical scheme adopts the combination of titanium alloy and metal beryllium, the titanium alloy and the metal beryllium are installed and matched in a new structural form, the titanium alloy which is relatively easy to machine and form is used for sealing the fluid metering channel, the titanium alloy and the beryllium pad are used for bearing pressure in a combined mode, and the beryllium pad is used for reducing the absorption of gamma rays. Thereby solving the problems of inconvenient processing, short service life, low reliability and the like caused by the problem of materials (ceramics).

Secondly, the invention provides a deduction metering method of the underwater flowmeter on the basis of adopting the titanium alloy as the packing material, and solves the problem of energy level coincidence caused by Compton scattering from the aspect of improving the accuracy of the gamma counting rate, thereby improving the metering accuracy. The technical scheme is as follows:

a deduction metering method of an underwater flowmeter is characterized by comprising the following steps:

step one, setting a ray receiving and transmitting system of the underwater flowmeter, penetrating the fluid metering channel by using any two groups of energy levels of the radioactive source group, and respectively acquiring gamma counting rates of corresponding first energy level and second energy level by the probe assemblyN；

Step two, respectively measuring the first and second empty pipe counting rates of two groups of energy levels under the condition that the fluid metering channel is emptied、；

Under the metering state, oil-gas-water three-phase mixed flow passes through the fluid metering channel, and the first and second measuring counting rates of two groups of energy levels are respectively measured、；

Step three, defining a first empty pipe deduction value on an empty pipe gamma absorption energy spectrumAnd a second empty pipe deduction value(ii) a Defining a first measurement subtraction value on a measured gamma absorption spectrumAnd a second measurement subtraction value；

Respectively counting the first empty pipeSecond empty tube count rateFirst measured count rateSecond measured count rateDeducting and correcting to obtain the first empty pipe deduction counting rateThe second empty tube deducts the counting rateFirst measurement deduct count rateSecond measurement deducted count rate；

；

；

；

；

Step four, calculating the gas phase content in the multiphase mixed flow according to the following formulaOil phase contentWater phase content of；

；

Wherein:

dthe distance of the gamma ray passing through the fluid metering channel is measured;

an absorption coefficient of gamma rays at a first energy level for the gas phase;

is the absorption coefficient of oil relative to gamma rays at a first energy level;

is the absorption coefficient of water relative to gamma rays at a first energy level;

is the absorption coefficient of the gas phase to gamma rays at the second energy level;

is the absorption coefficient of the oil relative to gamma rays at a second energy level;

is the absorption coefficient of water relative to gamma rays at a second energy level.

After the high-energy-level gamma ray is subjected to Compton scattering, the scattering low energy level of the high-energy-level gamma ray is coincided with the original low energy level, the high-energy-level gamma ray is reflected on a gamma absorption energy spectrum, and the counting rate is superposed and increased. According to the steps of the method, the counting rate of the original low energy level can be obtained by deducting the counting rate of the scattering low energy level obtained by detection on the gamma absorption energy spectrum.

Drawings

FIG. 1 is a schematic structural diagram of a ray transceiving system of an underwater flowmeter;

fig. 2 is a schematic diagram illustrating the assembling relationship among the collimator 22, the first beryllium pad 23 and the first isolation seat 24, and among the compression ring 32, the second beryllium pad 33 and the second isolation seat 34;

FIG. 3 is a graph of the corresponding 31keV subtraction on the bare tube gamma absorption spectrum of the Ba133 radiation sourceCorresponding to 81keV subtractionSchematic process diagram of (1).

Detailed Description

The present invention will be further described with reference to the following examples and the accompanying drawings.

Example 1:

as shown in fig. 1 and 2, a ray transceiving system of an underwater flowmeter comprises a flowmeter body 10, wherein a fluid metering channel penetrates through the flowmeter body 10, the fluid metering channel is conventionally set as a round hole channel, a transmitting window and a probing window which are respectively arranged at two sides of the fluid metering channel are arranged on the flowmeter body 10, the inner end of the transmitting window is opposite to the inner end of the probing window and is respectively communicated with the fluid metering channel, a ray transmitting module is arranged in the transmitting window, a ray probing module is arranged in the probing window, the ray transmitting module transmits a ray and passes through the ray transmitting window perpendicular to a hole center line of the fluid metering channel, and the ray probing module probes and receives the ray passing through the fluid metering channel;

the ray emission module comprises a radiation source group 21, a collimator 22 and a first isolation seat 24 which are sequentially arranged, the first isolation seat 24 is positioned at the inner end of the emission window, the fluid metering channel and the emission window are separated and sealed by the first isolation seat 24, and the end surface of the inner end of the first isolation seat 24 is flush with and adapted to the inner wall of the fluid metering channel;

the ray exploring module comprises a probe assembly 31, a compression ring 32 and a second isolation seat 34 which are sequentially arranged, the second isolation seat 34 is positioned at the inner end of the exploring window, the fluid metering channel and the exploring window are separated and sealed by the second isolation seat 34, and the end surface of the inner end of the second isolation seat 34 is flush with and adapted to the inner wall of the fluid metering channel;

a first beryllium pad 23 is arranged between the collimator 22 and the first isolation seat 24, and the first isolation seat 24 is made of a titanium alloy material;

a second beryllium pad 33 is arranged between the compression ring 32 and the second isolation seat 34, and the second isolation seat 34 is made of a titanium alloy material.

A first embedding counter bore is arranged on the surface of the first isolation seat 24 facing the collimator 22, a first top block 221 matched with the first embedding counter bore is arranged on the collimator 22, a beryllium piece embedding opening is arranged on the first top block 221 and faces the hole bottom of the first embedding counter bore, the first beryllium pad 23 is embedded in the beryllium piece embedding opening and is matched with the beryllium piece embedding opening, the first top block 221 extends into the first embedding counter bore, the extending end of the first top block 221 is abutted against the hole bottom of the first embedding counter bore, the first beryllium pad 23 is abutted against the hole bottom of the first embedding counter bore, a collimating hole 22a penetrates through the collimator 22, the hole center line of the collimating hole 22a is perpendicular to and intersected with the hole center line of the fluid metering channel, the collimating hole 22a comprises two sections, the aperture of one section is smaller than that of the other section, and the small hole end of the collimating hole 22a faces the radiation source group 21, the large hole end of the collimation hole 22a is communicated with the beryllium piece embedding opening and faces to the first beryllium pad 23.

A second embedding counter bore is formed in the surface, facing the compression ring 32, of the second isolation seat 34, the second beryllium pad 33 is embedded in the second embedding counter bore and matched with the second beryllium pad, and the compression ring 32 compresses the second beryllium pad 33 and the second isolation seat 34 at the same time; the second embedded counter bore comprises a round hole section and a round table hole section, wherein the round hole section is close to the fluid metering channel, the round table hole section faces the compression ring 32, the second beryllium pad 33 is embedded in the round hole section, a circle of compression flange 321 is arranged on the end face, facing the second embedded counter bore, of the compression ring 32, the compression flange 321 is close to the inner ring of the compression ring 32, the inner ring of the compression flange 321 is flush with the inner ring of the compression ring 32, the compression flange 321 is embedded in the round table hole section, the outer ring of the compression flange 321 is matched with the hole wall of the round table hole section, the compression ring 32 and the compression flange 321 are integrally formed, the outer wall of the outer ring of the compression flange 321 and two end faces of the compression flange are in arc transition, and the large opening section of the round table hole section and the corresponding end face of the round table hole section are in arc transition, the stress concentration during pressure bearing is avoided, the compression ring 32 and the second isolation seat 34 are damaged, the end face of the embedded end of the compression flange 321 compresses the second beryllium pad 33, the compression ring 32 and the outer ring of the compression flange 321 compress the second isolation seat 34, and the thickness of the second beryllium pad 33 is larger than that of the first beryllium pad 23.

Example 2:

a deduction metering method of an underwater flowmeter is carried out according to the following steps:

step one, setting the ray transceiving system of the underwater flowmeter according to embodiment 1, penetrating the fluid metering channel by using any two energy levels of the radiation source group 21, and acquiring gamma counting rates of corresponding first and second energy levels by the probe assembly 31 respectivelyN；

The radiation source group 21 can adopt a Ba133 radiation source group, the Ba133 radiation source mainly has three energy levels for flow measurement, namely 31keV, 81keV and 356 keV, and as a specific implementation mode, multiphase flow is measured by using the two energy levels of 31keV and 81keV of Ba 133;

step two, under the condition that the fluid metering channel is emptied, respectively measuring and obtaining the first and second empty pipe counting rates of two groups of energy levels by the probe assembly 31、；

Under the metering state, the oil-gas-water three-phase mixed flow passes through the fluid metering channel, and the probe assembly 31 respectively measures and obtains the first and second measurement counting rates of two groups of energy levels、；

Step three, defining a first empty pipe deduction value on an empty pipe gamma absorption energy spectrumAnd a second empty pipe deduction value(ii) a Defining a first measurement subtraction value on a measured gamma absorption spectrumAnd a second measurement subtraction value；

Specifically, the first empty pipe deduction valueSecond empty pipe deduction valueFirst measurement deduction valueThe second measurement deduction valueAre calculated according to the following method:

defining deduction ranges corresponding to a first energy level and a second energy level on the empty tube gamma absorption energy spectrum and the measured gamma absorption energy spectrum respectively, wherein the deduction ranges comprise two deduction lineages vertical to the abscissa axis of the gamma absorption energy spectrum, the two deduction lineages are located on two sides of the peak top value of the corresponding energy level, and intersection points of the two deduction lineages and the abscissa axis of the corresponding gamma absorption energy spectrum are respectively intersection points、The intersection points of the two deduction lineation lines and the corresponding gamma absorption energy spectrum spectral lines are respectively、；

i=0，x；

j=1，2；

The first empty pipe deduction valueDefined to correspond to a first energy level in the gamma absorption spectrum of the blank tube，，，The trapezoidal or rectangular area formed by the four points;

the second empty pipe deduction valueDefined for corresponding to a second energy level in the gamma absorption spectrum of the empty tube，，，The trapezoidal or rectangular area formed by the four points;

the first measurement deduction valueDefined for corresponding to a first energy level in the measured gamma absorption spectrum，，，The trapezoidal or rectangular area formed by the four points;

the above-mentionedSecond measurement deduction valueDefined for corresponding to a second energy level in the measured gamma absorption spectrum，，，The trapezoidal or rectangular area formed by the four points;

respectively counting the first empty pipeSecond empty tube count rateFirst measured count rateSecond measured count rateDeducting and correcting to obtain the first empty pipe deduction counting rateThe second empty tube deducts the counting rateFirst measurement deduct count rateSecond measurement deducted count rate；

；

；

；

；

FIG. 3 shows the corresponding first energy level (31 keV) subtraction on the bare tube gamma absorption spectrum of the Ba133 radiation sourceAnd corresponding second energy level (81 keV) subtractionThe process of (1), wherein two deduction lines are manually set, and after manually setting the deduction lines,、、、are all constants, the set position of the deduction line has a somewhat smaller influence on the metrology results, but within an acceptable degree, for example the first energy level (31 keV) on the gamma absorption spectrum of the blank tube:

the probe assembly 31 measuresIs/are as followsActually compriseAndtwo parts of whichThe gamma counting rate is the gamma counting rate which is obtained by probing a first energy level (31 keV) gamma ray emitted by the Ba133 by the probe assembly 31 after passing through a hollow tube; whileThe radiation with higher energy level emitted by the Ba133 (for example, a part of the radiation with energy level of 81 keV) is compton scattered and reduced to 31keV, and after passing through the empty tube, the radiation is detected by the probe assembly 31, and this part is superimposed on the gamma absorption spectrum of the empty tube as the radiation with first energy level (31 keV) emitted by the Ba133 itself, so that the absorption count rate of the 31keV gamma empty tube detected by the probe assembly 31 is distorted.

The same principle is that: corresponding second energy level (81 keV) subtraction on blank tube gamma absorption spectrumCorresponding to a first energy level (31 keV) subtraction on the measured gamma absorption spectrumCorresponding to a second energy level (81 keV) subtraction on the measured gamma absorption spectrumThe process of (2) is consistent with the above.

Step four, calculating the gas phase content in the multiphase mixed flow according to the following formulaOil phase contentWater phase content of；

；

Wherein:

dthe distance of the gamma ray passing through the fluid metering channel is the diameter of the fluid metering channel;

is the absorption coefficient of the gas phase to the gamma ray with the first energy level and is constant;

is the absorption coefficient of the oil relative to gamma rays at a first energy level, and is constant;

is the absorption coefficient of water relative to gamma rays at a first energy level, and is constant;

is the absorption coefficient of the gas phase to the gamma ray with the second energy level and is constant;

is the absorption coefficient of the oil relative to the gamma ray at the second energy level, and is constant;

at a relatively second energy level of waterThe absorption coefficient of gamma rays is constant.

Example 3:

the measurement method of example 2 was used to perform subtraction measurement on the tested multiphase mixed flow to obtain the subtracted water contentAnd obtaining the distorted water content by adopting the traditional metering methodThe real water content of the multiphase mixed flow is testedComparing, and calculating to obtain the error of the water-containing measurementW ₁And distorted moisture metering errorsW ₂. The difference between the conventional metering method and the embodiment 2 is only that: the traditional metering method does not comprise the step three, and the distorted water content is calculated by adopting the following formulaDistorted oil contentDistorted air ratio：

。

Water content measurement errorW ₁And distorted moisture metering errorsW ₂Respectively calculating according to the formula:

；

。

data such as the true water content of 5 test multiphase mixed flows randomly selected for comparison in the test process are shown in table 1:

TABLE 1 data sheet for testing true water content of multiphase mixed flow

Calculated water cut subtracted from 5 sets of test multiphase mixed streams corresponding to table 1Distorted water contentDeducting the water content metering errorW ₁And distorted moisture metering errorsW ₂See table 2:

TABLE 2 measurement of water content and water content in multiphase mixed flow

As can be seen from table 2: the water cut of subtraction obtained by measurement was calculated by the subtraction algorithm of example 2With true water contentRelatively closely, the corresponding metrology error (the subtracted moisture metrology error) is smaller than the error (the distorted moisture metrology error) of the conventional algorithm, which is not subtracted.

The beneficial effects of the invention are embodied in two aspects: on one hand, the structure is embodied, titanium alloy and metal beryllium are combined and are installed and matched in a new structural form, a fluid metering channel is sealed by the titanium alloy which is relatively easy to machine and form, the titanium alloy and the beryllium pad are combined to bear pressure, and the beryllium pad is adopted to reduce the absorption of gamma rays; thereby solving the problems of inconvenient processing, short service life, low reliability and the like caused by the problem of materials (ceramics). And the other side is represented on the measurement method, and the measurement is performed by deducting the detected scattering low-energy-level counting rate on the gamma absorption energy spectrum so as to obtain a result which is closer to the real counting rate, thereby avoiding the Compton scattering effect from causing great influence on the result of measuring the multiphase flow by the gamma rays and improving the measurement accuracy.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.