Flow measuring method based on differential pressure compensation and thick oil mixed-phase flowmeter

Abstract

The invention provides a flow measurement method based on differential pressure compensation and a thick oil mixed-phase flowmeter, relates to the technical field of flow measurement, and aims to solve the problem of low measurement precision of high-viscosity medium fluid. The method is applied to a flow computer of the thick oil miscible phase flowmeter, the thick oil miscible phase flowmeter further comprises a differential pressure sensor assembly and a measuring pipeline of a symmetrical structure, and the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section. Pressure measuring points of the differential pressure sensor assembly comprise a first pressure measuring point located on the inlet pipe section, a second pressure measuring point located on the throat pipe section and a third pressure measuring point located on the outlet pipe section. The method comprises the steps of obtaining a first differential pressure between a first pressure measuring point and a second pressure measuring point and a second differential pressure between the second pressure measuring point and a third pressure measuring point measured by a differential pressure sensor assembly, substituting a target difference value between the second differential pressure and the first differential pressure into a target equation to obtain a flow velocity of a to-be-measured fluid, and calculating the flow velocity of the to-be-measured fluid according to the flow velocity of the to-be-measured fluid. And obtaining the mass flow of the to-be-measured fluid.

Description

Technical Field

[0001] The present application relates to the technical field of flow measurement, and provides a flow measurement method based on differential pressure compensation and a heavy oil mixed-phase flowmeter. Background Art

[0002] At present, in the actual use of differential pressure flowmeters, it is often necessary to measure the flow of complex fluids with complex flow shapes and high viscosity (for example, heavy oil with high viscosity produced by oil wells in oil fields). When the fluid viscosity is high, friction will occur between the phases of the fluid in the differential pressure flowmeter, and the boundary of the fluid will also rub against the inner wall of the differential pressure flowmeter, resulting in a significant pressure drop in the tube (i.e., flow pressure drop) during the fluid transmission process, which seriously affects the accuracy of flow measurement using pressure difference, resulting in low measurement accuracy of traditional differential pressure flowmeters for high-viscosity fluids. Summary of the invention

[0003] The present application provides a flow measurement method based on differential pressure compensation and a heavy oil mixed phase flowmeter, which are used to solve the problem of low measurement accuracy of high viscosity fluids.

[0004] In a first aspect, a flow measurement method based on differential pressure compensation is provided, which is applied to a flow computer of a heavy oil mixed phase flow meter, wherein the heavy oil mixed phase flow meter further comprises a flow meter body and a differential pressure sensor assembly, wherein a measuring pipeline with a symmetrical structure is arranged in the flow meter body, wherein the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section; the pressure measuring points of the differential pressure sensor assembly comprise a first pressure measuring point located at the inlet pipe section, a second pressure measuring point located at the throat pipe section and a third pressure measuring point located at the outlet pipe section, wherein the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point; the heavy oil mixed phase flow meter is vertically installed, and the method comprises:

[0005] Acquire a first differential pressure between the first pressure measuring point and the second pressure measuring point and a second differential pressure between the second pressure measuring point and the third pressure measuring point measured by the differential pressure sensor assembly;

[0006] calculating a difference between the second differential pressure and the first differential pressure to obtain a target differential;

[0007] Substituting the target difference into the target equation, solving to obtain the flow rate of the measured fluid at the second pressure measuring point; the measured fluid includes a high-viscosity medium; the target equation is determined according to the first form-resistance pressure drop and the first conversion pressure drop between the first pressure measuring point and the second pressure measuring point, and the second form-resistance pressure drop and the second conversion pressure drop between the second pressure measuring point and the third pressure measuring point; the first conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the first pressure measuring point and the second pressure measuring point, and the second conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the second pressure measuring point and the third pressure measuring point;

[0008] The mass flow rate of the fluid to be measured is obtained according to the flow velocity of the fluid to be measured at the second pressure measuring point.

[0009] Optionally, the target equation is used to indicate that the target difference is equal to the sum of the form-resistance pressure drop difference and the conversion pressure drop difference, the form-resistance pressure drop difference is the difference between the second form-resistance pressure drop and the first form-resistance pressure drop, and the conversion pressure drop difference is the difference between the second conversion pressure drop and the first conversion pressure drop.

[0010] Optionally, the objective equation is expressed as follows:

[0011]

[0012] Wherein, ΔP is the target difference, is the form-resistance pressure drop difference, ρu2 2 (1-β 4 ) is the conversion pressure drop difference, u2 is the flow rate of the measured fluid at the second pressure measuring point, K is a preset coefficient related to the shape of the measuring pipeline, ρ is the density of the measured fluid, and β is the ratio between the diameter of the throat pipe section and the diameter of the outlet pipe section.

[0013] Optionally, obtaining the mass flow rate of the fluid to be measured according to the flow velocity of the fluid to be measured at the second pressure measuring point includes:

[0014] The density of the fluid to be measured, the cross-sectional area of ​​the throat pipe section, and the flow velocity of the fluid to be measured at the second pressure measuring point are multiplied to obtain the mass flow rate of the fluid to be measured.

[0015] Optionally, the fluid to be measured is a multiphase medium including a high-viscosity medium; a photon generator and a photon detector are further provided in the flow meter body, wherein the photon generator is configured to generate photons of different energy levels; and the photon detector is configured to measure the actual transmission quantity of the photons of different energy levels under the influence of the fluid to be measured;

[0016] After calculating the mass flow rate of the fluid to be measured according to the flow velocity of the fluid to be measured at the second pressure measuring point, the method further includes:

[0017] Obtaining the actual transmission quantity measured by the photon detector;

[0018] Calculating the phase fraction of each phase medium in the fluid to be measured according to the actual transmission quantity;

[0019] The mass flow rate of each phase of the medium is calculated according to the mass flow rate of the fluid to be measured and the phase fraction of each phase of the medium.

[0020] Optionally, after calculating the mass flow rate of each phase medium according to the mass flow rate of the fluid to be measured and the phase fraction of each phase medium, the method further includes:

[0021] The volume flow rate of each phase medium is calculated based on the mass flow rate of each phase medium and the density of each phase medium.

[0022] In a second aspect, a heavy oil mixed phase flow meter is provided, the heavy oil mixed phase flow meter comprising a flow meter body, a differential pressure sensor assembly and a flow computer, wherein a measuring pipeline with a symmetrical structure is arranged in the flow meter body; the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section;

[0023] The pressure measuring points of the differential pressure sensor assembly include a first pressure measuring point, a second pressure measuring point and a third pressure measuring point, the first pressure measuring point is arranged at the inlet pipe section, the second pressure measuring point is arranged at the throat pipe section, the third pressure measuring point is arranged at the outlet pipe section, and the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point;

[0024] The differential pressure sensor assembly is used to measure a first differential pressure between the first pressure measuring point and the second pressure measuring point, and a second differential pressure between the second pressure measuring point and the third pressure measuring point;

[0025] The flow computer is communicatively connected to the differential pressure sensor assembly for controlling the working state of the differential pressure sensor assembly. The flow computer also stores a computer program and can execute the computer program to implement the flow measurement method based on differential pressure compensation as described in any one of the first aspects.

[0026] Optionally, a photon generator and a photon detector are further provided in the flow meter body; the photon detector and the photon generator are arranged opposite to each other;

[0027] The photon generator is used to generate photons of different energy levels;

[0028] The photon detector is used to measure the actual transmission quantity of photons of different energy levels under the influence of the fluid to be measured;

[0029] The flow computer is respectively connected to the photon generator and the photon detector for communication, and is also used to control the working states of the photon generator and the photon detector.

[0030] Optionally, the second pressure measuring point includes a fourth pressure measuring point and a fifth pressure measuring point symmetrically arranged about the measuring pipeline, the first pressure measuring point and the fourth pressure measuring point are located on the same axis on one side of the measuring pipeline, and the fifth pressure measuring point and the third pressure measuring point are located on the same axis on the other side of the measuring pipeline;

[0031] The differential pressure sensor assembly includes a first differential pressure sensor and a second differential pressure sensor, wherein the first differential pressure sensor is used to measure a first differential pressure between the first pressure measuring point and the fourth pressure measuring point; and the second differential pressure sensor is used to measure a second differential pressure between the fifth pressure measuring point and the third pressure measuring point.

[0032] Optionally, the first pressure measuring point, the second pressure measuring point and the third pressure measuring point are located on the same axis on one side of the measuring pipeline, and the differential pressure sensor assembly is an integrated differential pressure sensor.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present application provides a flow measurement method based on differential pressure compensation, which is applied to a flow computer of a heavy oil mixed phase flow meter, wherein the heavy oil mixed phase flow meter further comprises a flow meter body and a differential pressure sensor assembly, wherein a measuring pipeline of a symmetrical structure is arranged in the flow meter body, wherein the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section; wherein the pressure measuring points of the differential pressure sensor assembly comprise a first pressure measuring point located at the inlet pipe section, a second pressure measuring point located at the throat pipe section and a third pressure measuring point located at the outlet pipe section, wherein the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point; wherein the heavy oil mixed phase flow meter is vertically installed, wherein the method comprises:

[0035] Obtain a first differential pressure between a first pressure measuring point and a second pressure measuring point, and a second differential pressure between a second pressure measuring point and a third pressure measuring point measured by a differential pressure sensor assembly; calculate the difference between the second differential pressure and the first differential pressure to obtain a target differential pressure; substitute the target differential pressure into a target equation, and solve to obtain the flow rate of the fluid to be measured at the second pressure measuring point; the fluid to be measured includes a high-viscosity medium; the target equation is determined based on a first form-resistance pressure drop and a first conversion pressure drop between the first pressure measuring point and the second pressure measuring point, and a second form-resistance pressure drop and a second conversion pressure drop between the second pressure measuring point and the third pressure measuring point; the first conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the first pressure measuring point and the second pressure measuring point, and the second conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the second pressure measuring point and the third pressure measuring point; obtain the mass flow rate of the fluid to be measured based on the flow rate of the fluid to be measured at the second pressure measuring point.

[0036] In the present application, since the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point, and the structure of the measuring pipeline is symmetrical, the installation method of the heavy oil mixed phase flowmeter is vertical installation. At this time, the friction pressure drop from the first pressure measuring point to the second pressure measuring point and from the second pressure measuring point to the third pressure measuring point is consistent, and the gravity pressure drop is also consistent, which can offset each other, thereby eliminating the influence of the friction pressure drop and gravity pressure drop on the measurement of the high viscosity fluid during the metering process, avoiding the calculation of the friction pressure drop and the gravity pressure drop, and according to the conversion of the form resistance pressure drop, the static pressure and the dynamic pressure, the flow rate of the high viscosity fluid can be accurately calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 An appearance diagram of a heavy oil mixed phase flow meter provided in an embodiment of the present application;

[0039] Figure 2 A cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 1 ;

[0040] Figure 3 A cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 2 ;

[0041] Figure 4 A cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 3 ;

[0042] Figure 5A schematic flow chart of a flow measurement method based on differential pressure compensation provided in an embodiment of the present application.

[0043] Markings in the figure: 1-flow meter body, 2-differential pressure sensor assembly, 3-flow computer, 4-measuring pipeline, 5-pressure pipe, 21-first differential pressure sensor, 22-second differential pressure sensor, 41-inlet pipe section, 42-throat pipe section, 43-outlet pipe section, 51-first pressure pipe, 52-second pressure pipe, 53-third pressure pipe, P1-first pressure measuring point, P2-second pressure measuring point, P3-third pressure measuring point, P2′-fourth pressure measuring point, P2″-fifth pressure measuring point. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily. In addition, although the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in an order different from that here.

[0045] In order to solve the problem of low measurement accuracy of high-viscosity fluids, an embodiment of the present application provides a flow measurement method based on differential pressure compensation. The method can be applied to a flow computer of a heavy oil mixed phase flow meter.

[0046] Please refer to Figure 1 , which is a structural diagram of the appearance of a heavy oil mixed phase flowmeter provided in an embodiment of the present application. The heavy oil mixed phase flowmeter comprises a flowmeter body 1, a differential pressure sensor assembly 2 and a flow computer 3, wherein the flow computer 3 is arranged in an instrument compartment on one side of the flowmeter body 1. The flow computer 3 is connected in communication with the differential pressure sensor assembly 2 to control the working state of the differential pressure sensor assembly 2. The flow computer 3 also stores a computer program and can execute the computer program to implement the flow measurement method based on differential pressure compensation provided in an embodiment of the present application.

[0047] Please refer to Figure 2 , which is a cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 1A symmetrical measuring pipe 4 is arranged in the flow meter body 1, and the measuring pipe 4 includes an expanded inlet pipe section 41, a contracted throat pipe section 42, and an expanded outlet pipe section 43. In other words, the pipe diameters of the inlet pipe section 41 and the outlet pipe section 43 are both larger than the pipe diameter of the throat pipe section 42. The measuring pipe 4 is a symmetrical structure, the pipe diameter of the inlet pipe section 41 is the same as the pipe diameter of the outlet pipe section 43, and the contraction angle from the inlet pipe section 41 to the throat pipe section 42 is the same as the expansion angle from the throat pipe section 42 to the outlet pipe section 43.

[0048] Please refer to Figure 3 and Figure 4 , Figure 3 A cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 2 , Figure 4 A cross-sectional view of a heavy oil mixed phase flow meter provided in an embodiment of the present application Figure 3 The pressure measuring points of the differential pressure sensor assembly 2 include a first pressure measuring point P1, a second pressure measuring point P2 and a third pressure measuring point P3. The first pressure measuring point P1 is set at the inlet pipe section 41, the second pressure measuring point P2 is set at the throat pipe section 42, and the third pressure measuring point P3 is set at the outlet pipe section 43. The distance from the first pressure measuring point P1 to the second pressure measuring point P2 is equal to the distance from the second pressure measuring point P2 to the third pressure measuring point P3. The differential pressure sensor assembly 2 is used to measure the first differential pressure between the first pressure measuring point P1 and the second pressure measuring point P2, and the second differential pressure between the second pressure measuring point P2 and the third pressure measuring point P3.

[0049] In the specific implementation process, the fluid to be measured enters the heavy oil mixed phase flowmeter through the inlet pipe section 41. When it flows through the throat pipe section 42, the flow rate of the fluid to be measured is accelerated due to the contraction of the pipe diameter of the throat pipe section 42. At this time, there is a pressure difference between the fluid at the inlet pipe section 41 and the fluid at the throat pipe section 42. The differential pressure sensor assembly 2 can measure the first differential pressure between the first pressure measuring point P1 and the second pressure measuring point P2. When the fluid to be measured flows out from the outlet pipe section 43, the flow rate of the fluid to be measured is reduced due to the expansion of the pipe diameter of the outlet pipe section 43. At this time, there is a pressure difference between the fluid at the throat pipe section 42 and the fluid at the outlet pipe section 43. The differential pressure sensor assembly 2 can measure the second differential pressure between the second pressure measuring point P2 and the third pressure measuring point P3. After measuring the first differential pressure and the second differential pressure, the differential pressure sensor assembly 2 sends the first differential pressure and the second differential pressure to the flow computer 3 for flow measurement.

[0050] Among them, the differential pressure sensor assembly 2 can be used Figure 3 and Figure 4 These two methods are introduced below.

[0051] Please continue to refer to Figure 3, the first pressure measuring point P1, the second pressure measuring point P2 and the third pressure measuring point P3 are located on the same axis of one side of the measuring pipe 4, and the differential pressure sensor assembly 2 is an integrated differential pressure sensor. At this time, the first pressure measuring point P1 and the third pressure measuring point P3 are symmetrically arranged with respect to the second pressure measuring point P2.

[0052] Please continue to refer to Figure 4 The second pressure measuring point P2 includes a fourth pressure measuring point P2′ and a fifth pressure measuring point P2″ which are symmetrically arranged about the measuring pipeline 4, the first pressure measuring point P1 and the fourth pressure measuring point P2′ are located on the same axis on one side of the measuring pipeline 4, and the fifth pressure measuring point P2″ and the third pressure measuring point P3 are located on the same axis on the other side of the measuring pipeline 4.

[0053] The differential pressure sensor assembly 2 includes a first differential pressure sensor 21 and a second differential pressure sensor 22. The first differential pressure sensor 21 is used to measure the first differential pressure between the first pressure measuring point P1 and the fourth pressure measuring point P2'; the second differential pressure sensor 22 is used to measure the second differential pressure between the fifth pressure measuring point P2" and the third pressure measuring point P3.

[0054] In a specific implementation process, the distance from the first pressure measuring point P1 to the fourth pressure measuring point P2′ is equal to the distance from the fifth pressure measuring point P2″ to the third pressure measuring point P3. After measuring the first differential pressure, the first differential pressure sensor 21 of the differential pressure sensor assembly 2 sends the first differential pressure to the flow computer 3. After measuring the second differential pressure, the second differential pressure sensor 22 of the differential pressure sensor assembly 2 sends the second differential pressure to the flow computer 3. The flow computer 3 performs flow measurement based on the first differential pressure and the second differential pressure.

[0055] In a possible embodiment, the flow meter body 1 and the differential pressure sensor assembly 2 may be connected via a rigid pressure-taking tube or a flexible pressure-measuring hose.

[0056] Please continue to refer to Figure 3 When the flow meter body 1 and the differential pressure sensor assembly 2 are connected via a rigid pressure-taking tube 5, the pressure-taking tube 5 includes a first pressure-taking tube 51, a second pressure-taking tube 52 and a third pressure-taking tube 53, wherein the flow meter body 1 and the first pressure measuring point P1 of the differential pressure sensor 2 are connected via the first pressure-taking tube 51, the flow meter body 1 and the second pressure measuring point P2 of the differential pressure sensor 2 are connected via the second pressure-taking tube 52, and the flow meter body 1 and the third pressure measuring point P3 of the differential pressure sensor 2 are connected via the third pressure-taking tube 53.

[0057] Please continue to refer to Figure 3The differential pressure sensor assembly 2 is an integrated differential pressure sensor. The first pressure-taking tube 51 is entirely a horizontal tube, the second pressure-taking tube 52 includes a horizontal tube and a vertical tube, and the third pressure-taking tube 53 also includes a horizontal tube and a vertical tube. In the specific implementation process, the second pressure-taking tube 52 and the third pressure-taking tube 53 are filled with water to eliminate the pressure influence of the vertical tube. The first pressure-taking tube 51 has no vertical tube and does not need to be filled with water.

[0058] In a possible embodiment, a photon generator and a photon detector are further provided in the flow meter body 1; the photon detector and the photon generator are arranged opposite to each other. The photon generator is used to generate photons of different energy levels; the photon detector is used to measure the actual transmission quantity of photons of different energy levels under the influence of the fluid to be measured. The flow computer 3 is respectively connected to the photon generator and the photon detector for communication, and is also used to control the working state of the photon generator and the photon detector.

[0059] As described above, the structure of the heavy oil mixed phase flowmeter is introduced. Based on the heavy oil mixed phase flowmeter of the aforementioned embodiment, the flow measurement method based on differential pressure compensation provided by the embodiment of the present application is introduced below. Figure 5 , which is a flow chart of a flow measurement method based on differential pressure compensation provided in an embodiment of the present application.

[0060] S501. Obtain a first differential pressure between a first pressure measuring point and a second pressure measuring point, and a second differential pressure between the second pressure measuring point and a third pressure measuring point measured by the differential pressure sensor assembly 2.

[0061] In the specific implementation process, the differential pressure sensor assembly 2 adopts Figure 3 or Figure 4 The structure measures the first differential pressure between the first pressure measuring point P1 and the second pressure measuring point P2 and the second differential pressure between the second pressure measuring point P2 and the third pressure measuring point P3, and then sends the first differential pressure and the second differential pressure to the flow computer 3.

[0062] S502: Calculate the difference between the second differential pressure and the first differential pressure to obtain a target differential pressure.

[0063] In a specific implementation process, after obtaining the first differential pressure and the second differential pressure, the flow computer 3 performs a subtraction operation on the second differential pressure and the first differential pressure to obtain a target difference value.

[0064] For example:

[0065] ΔP=ΔP 23 -ΔP 12

[0066] Among them, ΔP is the target difference, ΔP 12 is the first differential pressure, ΔP 23 is the second differential pressure.

[0067] S503: Substitute the target difference into the target equation to solve and obtain the flow rate of the fluid to be measured at the second pressure measuring point.

[0068] The fluid to be measured includes a high-viscosity medium, which refers to a medium with a viscosity greater than a preset threshold, such as thick oil. The fluid to be measured may be a single-phase medium including only the high-viscosity medium, or a multiphase medium including the high-viscosity medium. The multiphase medium may be a two-phase medium, such as a mixed-phase fluid of oil and water, or a three-phase medium, such as a mixed-phase fluid of oil, gas and water.

[0069] The target equation is determined based on the first form-resistance pressure drop and the first conversion pressure drop between the first pressure measuring point P1 and the second pressure measuring point P2, and the second form-resistance pressure drop and the second conversion pressure drop between the second pressure measuring point P2 and the third pressure measuring point P3; the first conversion pressure drop is obtained by the conversion of static pressure and dynamic pressure between the first pressure measuring point P1 and the second pressure measuring point P2, and the second conversion pressure drop is obtained by the conversion of static pressure and dynamic pressure between the second pressure measuring point P2 and the third pressure measuring point P3.

[0070] The pressure drop of the measured fluid during the flow process mainly includes friction pressure drop, gravity pressure drop, local form resistance pressure drop, etc. Friction pressure drop refers to the energy loss of fluid flow due to the friction between the fluid and the pipe wall and the viscous friction between the layers inside the fluid during the fluid flow process, thereby causing the pressure drop in the direction of fluid flow. Gravity pressure drop refers to the pressure drop caused by gravitational potential energy due to different heights when the heavy oil mixed phase flowmeter is installed vertically. Local form resistance pressure drop refers to the pressure drop caused by the shape change of the local area in the pipeline. In addition to these three pressure drops, the conversion of dynamic pressure and static pressure will also affect the pressure drop calculation of the flow process.

[0071] Since the distance from the first pressure measuring point P1 to the second pressure measuring point P2 is equal to the distance from the second pressure measuring point P2 to the third pressure measuring point P3, and the structure of the measuring pipeline is symmetrical, the first friction pressure drop between the first pressure measuring point P1 and the second pressure measuring point P2 is equal to the second friction pressure drop between the second pressure measuring point P2 and the third pressure measuring point P3. Since the distance from the first pressure measuring point P1 to the second pressure measuring point P2 is equal to the distance from the second pressure measuring point P2 to the third pressure measuring point P3, and the installation method of the heavy oil mixed phase flowmeter is vertical installation, the first gravity pressure drop between the first pressure measuring point P1 and the second pressure measuring point P2 is equal to the second gravity pressure drop between the second pressure measuring point P2 and the third pressure measuring point P3.

[0072] The first friction pressure drop and the second friction pressure drop can offset each other, and the first gravity pressure drop and the second gravity pressure drop can offset each other. Therefore, by determining the target equation based on the first form-resistance pressure drop, the second form-resistance pressure drop, the first conversion pressure drop, and the second conversion pressure drop, the measurement influence of the friction pressure drop and the gravity pressure drop on the high-viscosity fluid can be eliminated, thereby accurately measuring the flow rate of the fluid to be measured including the high-viscosity medium.

[0073] In a possible embodiment, the target equation is used to indicate that the target difference is equal to the sum of the form-resistance pressure drop difference and the conversion pressure drop difference, the form-resistance pressure drop difference is the difference between the second form-resistance pressure drop and the first form-resistance pressure drop, and the conversion pressure drop difference is the difference between the second conversion pressure drop and the first conversion pressure drop.

[0074] In a specific implementation process, the first pressure drop (first differential pressure) between the first pressure measuring point P1 and the second pressure measuring point P2 is equal to the sum of the first friction pressure drop, the first gravity pressure drop, the first form resistance pressure drop, and the first conversion pressure drop, which is specifically expressed as follows:

[0075] ΔP 12 =P f12 +P g12 +P l12 +P a12

[0076] Among them, ΔP 12 is the first pressure drop, P f12 is the first friction pressure drop, P g12 is the first gravity pressure drop, P l12 is the first form resistance voltage drop, P a12 is the first conversion pressure drop.

[0077] The second pressure drop (second differential pressure) between the second pressure measuring point P2 and the third pressure measuring point P3 is equal to the sum of the second friction pressure drop, the second gravity pressure drop, the second form resistance pressure drop, and the second conversion pressure drop, which is specifically expressed as follows:

[0078] ΔP 23 =P f23 +P g23 +P l23 +P a23

[0079] Among them, ΔP 23 is the second pressure drop, P f23 is the second friction pressure drop, P g23 is the second gravity pressure drop, P l23 is the second form resistance voltage drop, P a23 is the second conversion pressure drop.

[0080] Subtract the first pressure drop from the second pressure drop to get the target difference, since P f12 =P f23, the first friction pressure drop and the second friction pressure drop can offset each other, because P g12 =P g23 , the first gravity pressure drop and the second gravity pressure drop can offset each other, the second form-resistance pressure drop minus the first form-resistance pressure drop can obtain the form-resistance pressure drop difference, and the second conversion pressure drop minus the first conversion pressure drop can obtain the conversion pressure drop difference. Therefore, the target equation in which the target difference is equal to the sum of the form-resistance pressure drop difference and the conversion pressure drop difference can be obtained, which is specifically expressed as follows:

[0081] ΔP 23 -ΔP 12 =(P l23 -P l12 )+(P a23 -P a12 )

[0082] Due to the form resistance pressure drop difference is:

[0083]

[0084] The conversion pressure drop difference is:

[0085] P a23 -P a12 =ρu2 2 (1-β 4 )

[0086] The objective equation is finally expressed as follows:

[0087]

[0088] Among them, ΔP is the target difference, is the form resistance pressure drop difference, ρu2 2 (1-β 4 ) is the converted pressure drop difference, u2 is the flow rate of the measured fluid at the second pressure measuring point P2, K is a preset coefficient related to the shape of the measuring pipe 4, which is preset at the factory, ρ is the density of the measured fluid, and β is the ratio between the diameter of the throat section and the diameter of the outlet section.

[0089] Furthermore, after obtaining the target difference, the flow computer 3 substitutes the target difference into the above target equation and solves it to obtain the flow rate of the measured fluid at the second pressure measuring point.

[0090] S504: Obtain the mass flow rate of the fluid to be measured according to the flow velocity of the fluid to be measured at the second pressure measuring point.

[0091] In a possible embodiment, the flow computer 3 performs a product operation on the density of the fluid to be measured, the cross-sectional area of ​​the throat pipe section, and the flow velocity of the fluid to be measured at the second pressure measuring point to obtain the mass flow rate of the fluid to be measured.

[0092] For example:

[0093] Q=ρu2A

[0094] Wherein, Q is the mass flow rate of the fluid to be measured, A is the cross-sectional area of ​​the throat pipe section 42, that is, the fluid measurement cross-sectional area, ρ is the density of the fluid to be measured, and u2 is the flow velocity of the fluid to be measured at the second pressure measuring point P2.

[0095] In a possible embodiment, the fluid to be measured is a multiphase medium including a high-viscosity medium; after the flow computer 3 calculates the mass flow rate of the fluid to be measured according to the flow velocity of the fluid to be measured at the second pressure measuring point P2, it can also obtain the actual transmission quantity measured by the photon detector; calculate the phase fraction of each phase medium in the fluid to be measured according to the actual transmission quantity; calculate the mass flow rate of each phase medium according to the mass flow rate of the fluid to be measured and the phase fraction of each phase medium.

[0096] In the specific implementation process, the photons of various energy levels emitted by the photon generator are absorbed by different media (oil, gas, water) according to the absorption characteristics of the photon rays. The photon detector can detect the residual intensity of the photon, that is, the actual transmission quantity of the photon through the fluid to be measured. The flow computer 3 can calculate the phase fraction of each phase medium in the fluid to be measured according to the photon attenuation law and the actual transmission quantity. The phase fraction refers to the proportion of each phase medium in the fluid to be measured. Then, the mass flow rate of the fluid to be measured is multiplied by the phase fraction of each phase medium to obtain the mass flow rate of each phase medium.

[0097] For example:

[0098] Q i =m i ×Q

[0099] Where Q is the mass flow rate of the fluid to be measured, m i is the phase fraction of the i-th phase medium of the fluid to be measured, Q i is the mass flow rate of the i-th phase medium.

[0100] In the embodiment of the present application, the photon generator and photon detector in the heavy oil mixed phase flowmeter can be used to calculate the phase fraction of each phase medium in the multiphase medium. For the multiphase medium including the high viscosity medium, the mass flow rate of each phase medium can be accurately obtained.

[0101] In a possible embodiment, after calculating the mass flow rate of each phase medium according to the mass flow rate of the fluid to be measured and the phase fraction of each phase medium, the flow computer 3 can also calculate the volume flow rate of each phase medium according to the mass flow rate of each phase medium and the density of each phase medium.

[0102] In a specific implementation process, the flow computer 3 performs ratio calculation on the mass flow rate of each phase medium and the density of each phase medium to obtain the volume flow rate of each phase medium.

[0103] For example:

[0104] V i =Q i / ρ i

[0105] Among them, Q i is the mass flow rate of the i-th phase medium, ρ i is the density of the i-th phase medium, V i is the volume flow rate of the i-th phase medium.

[0106] In summary, the present application provides a flow measurement method based on differential pressure compensation, which eliminates the measurement influence of friction pressure drop and gravity pressure drop on high-viscosity fluid, avoids calculating friction pressure drop and gravity pressure drop, and thus accurately measures the mass flow and volume flow of high-viscosity fluid, which is particularly suitable for single well metering in the process of heavy oil production.

[0107] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0108] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not indicate the advantages or disadvantages of the embodiments.

[0109] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as a read-only memory / random access memory, a disk, an optical disk), including a number of instructions to enable a multimedia terminal device (which can be a mobile phone, a computer, a television receiver, or a network device, etc.) to execute the methods described in each embodiment of the present application. The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structures or equivalent process transformations made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are similarly included in the patent protection scope of the present application.

Claims

1. A flow measurement method based on differential pressure compensation, characterized in that: In a flow computer applied to a heavy oil mixed phase flow meter, the heavy oil mixed phase flow meter further comprises a flow meter body and a differential pressure sensor assembly, wherein a measuring pipeline of a symmetrical structure is arranged in the flow meter body, and the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section; the pressure measuring points of the differential pressure sensor assembly comprise a first pressure measuring point located at the inlet pipe section, a second pressure measuring point located at the throat pipe section and a third pressure measuring point located at the outlet pipe section, and the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point; The heavy oil mixed phase flow meter is installed vertically, and the method comprises: Acquire a first differential pressure between the first pressure measuring point and the second pressure measuring point and a second differential pressure between the second pressure measuring point and the third pressure measuring point measured by the differential pressure sensor assembly; calculating a difference between the second differential pressure and the first differential pressure to obtain a target differential; Substituting the target difference into the target equation, solving to obtain the flow rate of the measured fluid at the second pressure measuring point; the measured fluid includes a high-viscosity medium; the target equation is determined according to the first form-resistance pressure drop and the first conversion pressure drop between the first pressure measuring point and the second pressure measuring point, and the second form-resistance pressure drop and the second conversion pressure drop between the second pressure measuring point and the third pressure measuring point; the first conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the first pressure measuring point and the second pressure measuring point, and the second conversion pressure drop is obtained by converting the static pressure and the dynamic pressure between the second pressure measuring point and the third pressure measuring point; The mass flow rate of the fluid to be measured is obtained according to the flow velocity of the fluid to be measured at the second pressure measuring point.

2. The flow measurement method based on differential pressure compensation according to claim 1, characterized in that: The target equation is used to indicate that the target difference is equal to the sum of the form-resistance pressure drop difference and the conversion pressure drop difference, the form-resistance pressure drop difference is the difference between the second form-resistance pressure drop and the first form-resistance pressure drop, and the conversion pressure drop difference is the difference between the second conversion pressure drop and the first conversion pressure drop.

3. The flow measurement method based on differential pressure compensation according to claim 2, characterized in that: The objective equation is expressed as follows: Wherein, ΔP is the target difference, is the form-resistance pressure drop difference, ρu2 2 (1-β 4 ) is the conversion pressure drop difference, u2 is the flow rate of the measured fluid at the second pressure measuring point, K is a preset coefficient related to the shape of the measuring pipeline, ρ is the density of the measured fluid, and β is the ratio between the diameter of the throat pipe section and the diameter of the outlet pipe section.

4. The flow measurement method based on differential pressure compensation according to claim 1, characterized in that: The step of obtaining the mass flow rate of the fluid to be measured according to the flow rate of the fluid to be measured at the second pressure measuring point comprises: The density of the fluid to be measured, the cross-sectional area of ​​the throat pipe section, and the flow velocity of the fluid to be measured at the second pressure measuring point are multiplied to obtain the mass flow rate of the fluid to be measured.

5. The flow measurement method based on differential pressure compensation according to claim 1, characterized in that: The fluid to be measured is a multiphase medium including a high-viscosity medium; a photon generator and a photon detector are also arranged in the flow meter body, wherein the photon generator is arranged to generate photons of different energy levels; and the photon detector is used to measure the actual transmission quantity of the photons of different energy levels under the influence of the fluid to be measured; After calculating the mass flow rate of the fluid to be measured according to the flow rate of the fluid to be measured at the second pressure measuring point, the method further includes: Obtaining the actual transmission quantity measured by the photon detector; Calculating the phase fraction of each phase medium in the fluid to be measured according to the actual transmission quantity; The mass flow rate of each phase of the medium is calculated according to the mass flow rate of the fluid to be measured and the phase fraction of each phase of the medium.

6. The flow measurement method based on differential pressure compensation according to claim 5, characterized in that: After calculating the mass flow rate of each phase medium according to the mass flow rate of the fluid to be measured and the phase fraction of each phase medium, the method further includes: The volume flow rate of each phase medium is calculated based on the mass flow rate of each phase medium and the density of each phase medium.

7. A heavy oil mixed phase flow meter, characterized in that: The heavy oil mixed phase flow meter comprises a flow meter body, a differential pressure sensor assembly and a flow computer, wherein a measuring pipeline with a symmetrical structure is arranged in the flow meter body; the measuring pipeline comprises an expanded inlet pipe section, a contracted throat pipe section and an expanded outlet pipe section; The pressure measuring points of the differential pressure sensor assembly include a first pressure measuring point, a second pressure measuring point and a third pressure measuring point, the first pressure measuring point is arranged at the inlet pipe section, the second pressure measuring point is arranged at the throat pipe section, the third pressure measuring point is arranged at the outlet pipe section, and the distance from the first pressure measuring point to the second pressure measuring point is equal to the distance from the second pressure measuring point to the third pressure measuring point; The differential pressure sensor assembly is used to measure a first differential pressure between the first pressure measuring point and the second pressure measuring point, and a second differential pressure between the second pressure measuring point and the third pressure measuring point; The flow computer is communicatively connected with the differential pressure sensor assembly for controlling the working state of the differential pressure sensor assembly. The flow computer also stores a computer program and can execute the computer program to implement the flow measurement method based on differential pressure compensation as described in any one of claims 1-6.

8. The heavy oil mixed phase flow meter according to claim 7, characterized in that: A photon generator and a photon detector are also arranged in the flow meter body; the photon detector and the photon generator are arranged facing each other; The photon generator is used to generate photons of different energy levels; The photon detector is used to measure the actual transmission quantity of photons of different energy levels under the influence of the fluid to be measured; The flow computer is respectively connected to the photon generator and the photon detector for communication, and is also used to control the working states of the photon generator and the photon detector.

9. The heavy oil mixed phase flow meter according to claim 7, characterized in that: The second pressure measuring point includes a fourth pressure measuring point and a fifth pressure measuring point symmetrically arranged about the measuring pipeline, the first pressure measuring point and the fourth pressure measuring point are located on the same axis on one side of the measuring pipeline, and the fifth pressure measuring point and the third pressure measuring point are located on the same axis on the other side of the measuring pipeline; The differential pressure sensor assembly includes a first differential pressure sensor and a second differential pressure sensor, wherein the first differential pressure sensor is used to measure a first differential pressure between the first pressure measuring point and the fourth pressure measuring point; and the second differential pressure sensor is used to measure a second differential pressure between the fifth pressure measuring point and the third pressure measuring point.

10. The heavy oil mixed phase flow meter according to claim 7, characterized in that: The first pressure measuring point, the second pressure measuring point and the third pressure measuring point are located on the same axis on one side of the measuring pipeline, and the differential pressure sensor assembly is an integrated differential pressure sensor.

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