CN114152317A - Underground flow measurement error correction system and method - Google Patents
Underground flow measurement error correction system and method Download PDFInfo
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Abstract
The invention relates to a system and a method for correcting underground flow measurement errors, which are characterized by comprising an ultrasonic sensing device and a flow calculation device; the ultrasonic sensing device is fixedly arranged on the outer wall of the pipeline to be detected and used for transmitting at least one ultrasonic wave and receiving the direct wave and the scattered wave which are correspondingly generated in the fluid of the pipeline to be detected; the flow calculation device is used for obtaining a time difference signal of the pipeline to be measured according to the direct wave received by the ultrasonic sensing device by adopting a time difference method, obtaining a frequency difference signal of the pipeline to be measured according to the scattered wave received by the ultrasonic sensing device by adopting a frequency difference method, and determining the flow velocity of the fluid in the pipeline to be measured after error correction according to the time difference signal and the frequency difference signal.
Description
Technical Field
The invention relates to the field of downhole fluid flow measurement, in particular to a system and a method for correcting downhole flow measurement errors.
Background
The gas-liquid two-phase flow is one of the main existing forms of the underground fluid of the oil field, and the accurate measurement of the flow of the underground fluid is an important research means for mastering the flow condition of the underground fluid, improving the production mode of the oil field and reasonably developing resources. Ultrasonic flow measurement has become an important method for downhole flow measurement with the advantages of good repeatability, high accuracy, wide measurement range and the like.
At present, in the prior art, the output signals of an ultrasonic sensor and/or a radio frequency antenna are adopted to judge the type of fluid and calculate the gas flow, the liquid flow and the total flow, so that the device can be directly connected on a blowout pipe line in series under the condition of no gas-liquid separation, and is suitable for measuring the split-phase flow and the total flow of any gas-liquid ratio in the whole blowout process of a gas well. In the prior art, piezoelectric ceramic rings and piezoelectric ceramic columns with different resonant frequencies are used as sensitive components, and are fixed on a sound wedge made of organic glass, so that ultrasonic waves with two frequencies are simultaneously generated at the same position of a pipeline, and the flow velocity of fluid in the pipeline can be accurately measured. In the prior art, an ultrasonic measurement unit and a differential pressure measurement unit are simultaneously adopted to measure parameters of gas-liquid two-phase flow in a pipeline, and a dynamic wave storage and dynamic time delay mechanism is introduced under the measurement of a two-phase medium, so that the problem of incomplete acquired echo signals caused by large difference of sound wave propagation speeds of ultrasonic waves in gas-phase and liquid-phase media in the existing sampling mechanism is solved.
However, due to the complexity of the gas-liquid two-phase flow, the fluid in the pipe is not completely pure, and often contains suspended particles, bubbles and other media, and the concentration of the suspended particles in the measured fluid is changed, and a single frequency difference method or time difference method measurement result has a certain error, so that the ultrasonic measurement error caused by the suspended particles needs to be corrected.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a system and a method for correcting an error in downhole flow measurement, which can correct an ultrasonic measurement error caused by suspended particles.
In order to achieve the purpose, the invention adopts the following technical scheme: in one aspect, a downhole flow measurement error correction system is provided, comprising an ultrasonic sensing device and a flow calculation device;
the ultrasonic sensing device is fixedly arranged on the outer wall of the pipeline to be detected and used for transmitting at least one ultrasonic wave and receiving the direct wave and the scattered wave which are correspondingly generated in the fluid of the pipeline to be detected;
the flow calculation device is used for obtaining a time difference signal of the pipeline to be detected according to the direct wave received by the ultrasonic sensing device by adopting a time difference method, obtaining a frequency difference signal of the pipeline to be detected according to the scattered wave received by the ultrasonic sensing device by adopting a frequency difference method, and determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the time difference signal and the frequency difference signal.
Further, the ultrasonic sensing device comprises a first ultrasonic sensor, a second ultrasonic sensor, a third ultrasonic sensor and a fourth ultrasonic sensor;
the first ultrasonic sensor, the second ultrasonic sensor, the third ultrasonic sensor and the fourth ultrasonic sensor are fixedly arranged on the outer wall of the pipeline to be measured in an X shape;
the first ultrasonic sensor and the second ultrasonic sensor which are positioned on the same oblique line are both used for transmitting ultrasonic waves at least once to each other and receiving direct waves correspondingly generated in the fluid of the pipeline to be measured;
and the third ultrasonic sensor and the fourth ultrasonic sensor which are positioned on the same oblique line are used for receiving scattered waves correspondingly generated in the fluid of the pipeline to be measured.
Furthermore, the first ultrasonic sensor, the second ultrasonic sensor, the third ultrasonic sensor and the fourth ultrasonic sensor are fixed in a diagonal alignment mode.
Further, the ultrasonic waves emitted by the first ultrasonic sensor and the second ultrasonic sensor include high-frequency ultrasonic waves and low-frequency ultrasonic waves.
Further, the frequency difference method adopts a doppler frequency difference method.
Further, the flow calculation device is internally provided with:
the time difference calculation module is used for obtaining time difference signals of the pipelines to be detected under different frequencies according to the direct waves received by the first ultrasonic sensor and the second ultrasonic sensor by adopting a time difference method;
the frequency difference calculating module is used for obtaining frequency difference signals of the pipeline to be detected under different frequencies according to scattered waves received by the third ultrasonic sensor and the fourth ultrasonic sensor by adopting a frequency difference method;
and the flow velocity calculation module is used for determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the obtained time difference signal and frequency difference signal.
In another aspect, a downhole flow measurement error correction method is provided, comprising:
arranging an ultrasonic sensing device on the outer wall of the pipeline to be detected;
the ultrasonic sensing device transmits ultrasonic waves for at least one time and receives direct waves and scattered waves which are correspondingly generated in fluid of a pipeline to be detected;
obtaining time difference signals of the pipeline to be measured under different frequencies by adopting a time difference method according to the received direct waves;
obtaining frequency difference signals of the pipeline to be detected under different frequencies by adopting a frequency difference method according to the received scattered waves;
and determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the obtained time difference signal and the frequency difference signal.
Further, set up ultrasonic sensing device in the outer wall department of the pipeline that awaits measuring, include:
the outer wall of the pipeline to be measured is provided with a first ultrasonic sensor, a second ultrasonic sensor, a third ultrasonic sensor and a fourth ultrasonic sensor in an X shape, wherein the first ultrasonic sensor and the second ultrasonic sensor are located on the same inclined line, and the third ultrasonic sensor and the fourth ultrasonic sensor are located on the same inclined line.
Further, the ultrasonic sensing device transmits ultrasonic waves at least once and receives direct waves and scattered waves which are correspondingly generated in the fluid of the pipeline to be measured, and the ultrasonic sensing device comprises:
the first ultrasonic sensor transmits at least one ultrasonic wave with different frequencies to the direction of the second ultrasonic sensor, the second ultrasonic sensor receives a direct wave correspondingly generated in the fluid of the pipeline to be detected, and the fourth ultrasonic sensor receives a scattered wave correspondingly generated in the fluid of the pipeline to be detected;
the second ultrasonic sensor transmits at least one ultrasonic wave with different frequencies to the first ultrasonic sensor, the first ultrasonic sensor receives the direct wave correspondingly generated in the fluid of the pipeline to be measured, and the third ultrasonic sensor receives the scattered wave correspondingly generated in the fluid of the pipeline to be measured.
Further, the determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the obtained time difference signal and the obtained frequency difference signal includes:
determining the weight of each effective signal according to the proportion of the effective time difference signals obtained by adopting a time difference method to the total effective signals under different frequencies and the proportion of the effective frequency difference signals obtained by adopting a frequency difference method to the total effective signals under different frequencies;
and calculating the flow velocity of the fluid in the pipeline to be detected after error correction according to the weighted effective signal.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. according to the invention, by combining the time difference method and the frequency difference method of the ultrasonic wave, the error of the underground suspended particles on the gas-liquid two-phase flow is corrected, the influence of the measured invalid signals containing the suspended particles and the like on the test result can be avoided, the gas-liquid two-phase flow error is effectively corrected, and the calculation precision of the ultrasonic gas-liquid two-phase flow is further improved.
2. The invention can obtain the flow of gas-liquid two-phase flow by accumulating the flow velocity obtained by multiple measurements and simultaneously according to the calculated relationship among the flow velocity, the pipe diameter and the flow, effectively corrects the error of solid-phase particles and bubbles on the flow of the gas-liquid two-phase flow, and further overcomes one or more problems caused by the limitation and the defect of the related technology to at least a certain extent.
In conclusion, the invention can be widely applied to the field of downhole fluid flow measurement.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Like reference numerals refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a schematic view of an ultrasonic sensing device according to an embodiment of the present invention;
FIG. 2 is a schematic view of the direct and scattering of ultrasonic waves in a pipe according to an embodiment of the present invention;
fig. 3 is a flowchart of a method provided by an embodiment of the invention.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be used.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
For convenience of description, spatially relative terms, such as "inner", "outer", "lower", "upper", and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.
According to the system and the method for correcting the underground flow measurement error, a mode of combining a time difference method and a frequency difference method is adopted, firstly, high-frequency ultrasonic waves are transmitted by two ultrasonic sensors at the diagonal positions of an X array, scattered waves and direct waves are respectively received by two opposite ultrasonic sensors, and received effective signals are recorded by transmitting the high-frequency ultrasonic waves for multiple times; secondly, the two ultrasonic sensors at the diagonal positions of the X array emit low-frequency ultrasonic waves, and respectively receive scattered waves and direct waves in the same way. Finally, different weights are applied to the effective frequency difference signal and the effective time difference signal received in the two modes, and the flow speed is calculated according to the weighted time difference signal and the weighted frequency difference signal, so that the influence of the measured invalid signal containing suspended particles and the like on the test result can be avoided, the gas-liquid two-phase flow error can be effectively corrected, and the flow calculation precision of the ultrasonic gas-liquid two-phase flow can be further improved.
Example 1
As shown in fig. 1, the present embodiment provides a downhole flow measurement error correction system, which includes an ultrasonic sensing device 1 and a flow calculation device, wherein the ultrasonic sensing device 1 includes a first ultrasonic sensor 11, a second ultrasonic sensor 12, a third ultrasonic sensor 13, and a fourth ultrasonic sensor 14.
The first ultrasonic sensor 11, the second ultrasonic sensor 12, the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 are fixed on the outer wall of the pipeline 2 to be measured in an X shape. The first ultrasonic sensor 11 and the second ultrasonic sensor 12 located on the same oblique line are both used for transmitting ultrasonic waves at least once to each other and receiving direct waves correspondingly generated in the fluid of the pipe 2 to be measured. The third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 located on the same oblique line are used for receiving scattered waves correspondingly generated in the fluid of the pipe 2 to be measured.
The flow calculation device is used for obtaining a time difference signal of the pipeline 2 to be detected according to the direct waves received by the first ultrasonic sensor 11 and the second ultrasonic sensor 12 by adopting a time difference method, obtaining a frequency difference signal of the pipeline 2 to be detected according to scattered waves received by the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 by adopting a Doppler frequency difference method, and determining the flow velocity of the fluid in the pipeline 2 to be detected after error correction according to the obtained time difference signal and frequency difference signal, wherein the flow velocity is the flow velocity after the error generated by the suspended particles and the bubbles is corrected.
Specifically, first, the first ultrasonic sensor 11 emits ultrasonic waves, the emitted ultrasonic waves generate direct waves and scattered waves in the fluid of the pipe 2 to be measured, and the direct waves and the scattered waves are received by the second ultrasonic sensor 12 and the fourth ultrasonic sensor 14, respectively; next, the second ultrasonic sensor 12 emits ultrasonic waves, which generate direct waves and scattered waves in the fluid of the pipe 2 to be measured, and the first ultrasonic sensor 11 and the third ultrasonic sensor 13 are used to receive the direct waves and the scattered waves, respectively. The speed of ultrasonic wave propagating in the fluid is the superposition of the ultrasonic wave speed and the liquid flow speed on a speed field, the time difference method is used for calculating the flow speed by utilizing the difference of the forward flow existing time and the backward flow existing time of the ultrasonic wave in the same propagation path, the frequency difference method is used for enabling the particles to move along with the flow of the fluid, the emitted ultrasonic wave generates frequency shift after being scattered, and the flow speed is calculated by utilizing the front-back frequency difference. The doppler difference method is based on the acoustic doppler effect, and when there is relative motion between the sound source and the observer, the observer perceives the sound at a frequency different from the frequency emitted by the sound source. And analyzing the relation between the fluid flow velocity and the frequency difference generated by the change of the corresponding ultrasonic central frequency by combining the ultrasonic Doppler principle, and realizing the measurement of the flow of the measured fluid by calculating the frequency difference. Therefore, a set of received (forward and backward) direct wave signals can be used for a time difference calculation, and the received scattered waves can be used for a frequency difference calculation. That is, by using this measurement method, a set of echo signals calculated by the time difference method can be obtained, and two sets of echo signals processed by the doppler frequency difference method can also be obtained.
More specifically, as shown in fig. 2, the ultrasonic wave emitted by the ultrasonic sensor is directly emitted and scattered in the pipe. Assuming that the first ultrasonic sensor 11 emits ultrasonic waves in the P direction, when encountering pure fluid, the ultrasonic signal reaches the second ultrasonic sensor 12 in the form of direct waves; when a fluid with more suspended particles is encountered, the normal propagation of the ultrasonic wave is blocked, so that the ultrasonic wave signal is scattered, and the fourth ultrasonic sensor 14 can be used for receiving the scattered wave. On the basis of the above, the second ultrasonic sensor 12 emits ultrasonic waves in the opposite direction P, and when the pure fluid is encountered, the ultrasonic signals reach the first ultrasonic sensor 11 in the form of direct waves; when encountering a fluid with a large amount of suspended particles, the scattered waves are received by the third ultrasonic sensor 13. By a diagonal transmission, the received signals of the first ultrasonic sensor 11 and the second ultrasonic sensor 12 are subtracted to obtain a set of time difference signals, and the received signals of the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 are obtained two frequency difference signals.
More specifically, to perform error correction on the flow rate of the fluid with different suspended particle contents, ultrasonic signals of different frequencies may be alternately emitted diagonally by the first ultrasonic sensor 11 and the second ultrasonic sensor 12, while the direct wave and the scattered wave are obtained by the second ultrasonic sensor 12 and the fourth ultrasonic sensor 14, and the first ultrasonic sensor 11 and the third ultrasonic sensor 13, respectively. A set of time difference signals is derived from the received signals of the second ultrasonic sensor 12 and the first ultrasonic sensor 11, while two frequency difference signals are derived from the received signals of the fourth ultrasonic sensor 14 and the third ultrasonic sensor 13. The obtained time difference signal and the obtained frequency difference signal are processed, and flow measurement errors caused by suspended particles can be corrected by combining the flow measurement principles of the time difference method and the frequency difference method.
In a preferred embodiment, the first ultrasonic sensor 11 and the second ultrasonic sensor 12, and the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 are fixed in a diagonal alignment manner.
In a preferred embodiment, both the first ultrasonic sensor 11 and the second ultrasonic sensor 12 can emit high-frequency ultrasonic waves and low-frequency ultrasonic waves.
In a preferred embodiment, a time difference calculation module, a frequency difference calculation module and a flow velocity calculation module are arranged in the flow calculation device.
And the time difference calculation module is used for obtaining time difference signals of the pipeline 2 to be detected under different frequencies by adopting a time difference method according to the direct waves received by the first ultrasonic sensor 11 and the second ultrasonic sensor 12. And the frequency difference calculating module is used for obtaining frequency difference signals of the pipeline 2 to be detected under different frequencies according to the scattered waves received by the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 by adopting a Doppler frequency difference method. And the flow velocity calculation module is used for determining the flow velocity of the fluid in the pipeline 2 to be detected after error correction according to the obtained time difference signal and frequency difference signal.
In a preferred embodiment, a pressure-bearing protective shell 3 is arranged on the outer side of the pipeline to be measured corresponding to the position of the ultrasonic sensing device 1, and the pressure-bearing protective shell 3 is used for protecting the ultrasonic sensor and the driving circuit from being damaged by underground high-pressure fluid.
Example 2
As shown in fig. 3, the present embodiment provides a downhole flow measurement error correction method, including the following steps:
1) the outer wall of the pipeline 2 to be measured is provided with a first ultrasonic sensor 11, a second ultrasonic sensor 12, a third ultrasonic sensor 13 and a fourth ultrasonic sensor 14 in an X shape, wherein the first ultrasonic sensor 11 and the second ultrasonic sensor 12 are located on the same inclined line, and the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 are located on the same inclined line.
2) The first ultrasonic sensor 11 emits at least one ultrasonic wave with different frequencies in the direction of the second ultrasonic sensor 12, the second ultrasonic sensor 12 receives a direct wave generated correspondingly in the fluid of the pipe 2 to be measured, and the fourth ultrasonic sensor 14 receives a scattered wave generated correspondingly in the fluid of the pipe 2 to be measured.
3) The second ultrasonic sensor 12 emits at least one ultrasonic wave of different frequencies in the direction of the first ultrasonic sensor 11, the first ultrasonic sensor 11 receives a direct wave generated correspondingly in the fluid of the pipe 2 to be measured, and the third ultrasonic sensor 13 receives a scattered wave generated correspondingly in the fluid of the pipe 2 to be measured.
4) And obtaining time difference signals of the pipeline 2 to be measured under different frequencies by adopting a time difference method according to the direct waves received by the first ultrasonic sensor 11 and the second ultrasonic sensor 12.
5) And obtaining a frequency difference signal of the pipeline 2 to be measured under different frequencies by using a Doppler frequency difference method according to the scattered waves received by the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14.
Specifically, the first ultrasonic sensor 11 and the second ultrasonic sensor 12 may emit high-frequency ultrasonic waves and low-frequency ultrasonic waves.
More specifically, for example, the first ultrasonic sensor 11 and the second ultrasonic sensor 12 each transmit 100 times (transmit 50 times diagonally) the high-frequency ultrasonic wave and the low-frequency ultrasonic wave: first, high-frequency ultrasonic waves are transmitted 50 times by the first ultrasonic sensor 11 and the second ultrasonic sensor 12, and when the first ultrasonic sensor 11 transmits ultrasonic waves, direct waves and scattered waves are received by the second ultrasonic sensor 12 and the fourth ultrasonic sensor 14, respectively; when the second ultrasonic sensor 12 emits ultrasonic waves, direct waves and scattered waves are received by the first ultrasonic sensor 11 and the third ultrasonic sensor 13, respectively. Each time diagonal transmission is performed, a set of time difference signals and two sets of frequency difference signals can be obtained, and therefore, when the first ultrasonic sensor 11 and the second ultrasonic sensor 12 respectively transmit 50 times of high-frequency ultrasonic waves, effective values of 50 sets of time difference signals and 100 times of frequency difference signals under the high-frequency ultrasonic waves can be obtained. Similarly, the first ultrasonic sensor 11 and the second ultrasonic sensor 12 each transmit low-frequency ultrasonic waves 50 times, and effective values of 50 sets of time difference signals and 100 sets of frequency difference signals under the low-frequency ultrasonic waves are recorded.
6) Determining the weight of each effective signal according to the proportion of the effective time difference signal (i.e. the time difference signal within the preset reasonable range) obtained by adopting the time difference method to the total effective signal (i.e. the sum of the effective time difference signal and the effective frequency difference signal) and the proportion of the effective frequency difference signal (i.e. the frequency difference signal within the preset reasonable range) obtained by adopting the Doppler frequency difference method to the total effective signal under different frequencies, specifically:
6.1) determining the proportion of the effective time difference signals obtained by adopting a time difference method to the total effective signals under different frequencies.
6.2) determining the proportion of effective frequency difference signals obtained by adopting a Doppler frequency difference method to the total effective signals under different frequencies.
6.3) determining the weight of each effective signal according to the determined proportion:
setting the weight of the frequency difference signal in the high frequency state to W1The weight of the time difference signal is set to W2(ii) a Setting the weight of the frequency difference signal in the low frequency state to W3The weight of the time difference signal is set to W4Wherein W is1+W2+W3+W41. It should be noted that the weight isThe method can be obtained by analyzing the proportion rule of the effective signals in the total effective signals in the multiple measurement results.
7) And calculating the flow velocity of the fluid in the pipeline 2 to be detected after error correction according to the weighted effective signal, wherein the flow velocity is the flow velocity after the error generated by the suspended particles and the bubbles is corrected.
Specifically, as shown in fig. 1 and fig. 2, where α is an incident angle of the ultrasonic sensor, fig. 2 is a simplified ultrasonic sensor, assuming that a flow direction of the fluid is from left to right, a diameter of the pipe 2 to be measured through which the fluid flows is D, an ultrasonic incident angle is θ, a time difference method measures that the ultrasonic wave propagates forward from the first ultrasonic sensor 11 to the second ultrasonic sensor 12, and propagates backward from the second ultrasonic sensor 12 to the first ultrasonic sensor 11, assuming that a flow velocity of the fluid is v, a sound velocity in the fluid is c, a propagation velocity of the ultrasonic wave in the forward direction is c + v · sin θ, and a propagation velocity in the backward direction is c-v · sin θ, a difference Δ t between the ultrasonic backward flow and the forward flow is:
wherein, t21The propagation time of the ultrasonic wave in the countercurrent direction; t is t12Is the propagation time of the ultrasonic wave in the downstream direction.
The propagation speed of the ultrasonic wave in the general fluid is more than 1000m/s, which is far greater than the flow speed of the fluid to be measured, namely c2Is much greater than v2sin2θ, so v2sin2Theta may be omitted. Therefore, the fluid flow velocity v of the high-frequency ultrasonic wave and the low-frequency ultrasonic wave by the time difference methods-hAnd vs-lRespectively as follows:
wherein, Δ thAnd Δ tlThe time difference measured at high and low frequencies, respectively.
It is assumed that the continuous ultrasonic waves emitted from the first ultrasonic sensor 11 and the second ultrasonic sensor 12 have a frequency fTThe direction angle of the ultrasonic wave into the fluid is θ. Impurities in the fluid move in the same direction at the same velocity v as the fluid. When the scattered waves, which are acoustic signals emitted from the bubbles as a sound source, are received by the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14, the ultrasonic doppler difference Δ f received by the third ultrasonic sensor 13 and the fourth ultrasonic sensor 14 is:
wherein f isRAnd fTRespectively, the received frequency and the transmitted frequency.
Since the flow velocity of the foreign particles is very small compared to the sound velocity in the fluid, the flow velocity is related to the sound velocity c in the fluid and the frequency f of the transmitted signalTThe propagation direction angle theta of the ultrasonic wave and the Doppler frequency shift quantity delta f are related, and the sound velocity c is far larger than v sin theta, so the fluid flow velocity v of the high-frequency ultrasonic wave and the low-frequency ultrasonic wave by the frequency difference methodp-hAnd vp-lRespectively as follows:
the above formulas (2), (3), (5) and (6) are respectively fluid flow velocity calculation formulas obtained by single measurement by adopting a time difference method and a frequency difference method. After a plurality of times (assuming n times as a group) of high-frequency and low-frequency emission, calculating a primary speed and flow, wherein the flow speed after error correction is as follows:
wherein i is the number of effective signals; v. ofs-h iThe speed corresponding to the ith high-frequency time difference; v. ofs-l iThe speed corresponding to the ith low-frequency time difference; v. ofp-h iThe speed corresponding to the ith high-frequency difference; v. ofp-l iThe speed corresponding to the ith low frequency difference.
At this time, the flow rate Q of the fluid flowing through the pipe 2 to be measured in unit time is:
according to the invention, the time difference method and the frequency difference method are combined, the time difference method is used for measuring, the frequency difference signal is measured, the flow error caused by suspended particles and bubbles is corrected through the time difference signal and the frequency difference signal with different weights, and the stability and the adaptability of the gas-liquid two-phase flow measuring system can be improved.
The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims (10)
1. The underground flow measurement error correction system is characterized by comprising an ultrasonic sensing device and a flow calculation device;
the ultrasonic sensing device is fixedly arranged on the outer wall of the pipeline to be detected and used for transmitting at least one ultrasonic wave and receiving the direct wave and the scattered wave which are correspondingly generated in the fluid of the pipeline to be detected;
the flow calculation device is used for obtaining a time difference signal of the pipeline to be detected according to the direct wave received by the ultrasonic sensing device by adopting a time difference method, obtaining a frequency difference signal of the pipeline to be detected according to the scattered wave received by the ultrasonic sensing device by adopting a frequency difference method, and determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the time difference signal and the frequency difference signal.
2. The downhole flow measurement error correction system of claim 1, wherein the ultrasonic sensing device comprises a first ultrasonic sensor, a second ultrasonic sensor, a third ultrasonic sensor, and a fourth ultrasonic sensor;
the first ultrasonic sensor, the second ultrasonic sensor, the third ultrasonic sensor and the fourth ultrasonic sensor are fixed in a diagonal alignment mode.
3. The system of claim 2, wherein the first ultrasonic sensor, the second ultrasonic sensor, the third ultrasonic sensor and the fourth ultrasonic sensor are fixedly arranged on the outer wall of the pipe to be measured in an X shape;
the first ultrasonic sensor and the second ultrasonic sensor which are positioned on the same oblique line are both used for transmitting ultrasonic waves at least once to each other and receiving direct waves correspondingly generated in the fluid of the pipeline to be measured;
and the third ultrasonic sensor and the fourth ultrasonic sensor which are positioned on the same oblique line are used for receiving scattered waves correspondingly generated in the fluid of the pipeline to be measured.
4. The downhole flow measurement error correction system of claim 2, wherein the ultrasonic waves emitted by the first ultrasonic sensor and the second ultrasonic sensor comprise high frequency ultrasonic waves and low frequency ultrasonic waves.
5. The downhole flow measurement error correction system of claim 1, wherein the frequency difference method employs a doppler frequency difference method.
6. The downhole flow measurement error correction system of claim 2, wherein the flow calculation device has disposed therein:
the time difference calculation module is used for obtaining time difference signals of the pipelines to be detected under different frequencies according to the direct waves received by the first ultrasonic sensor and the second ultrasonic sensor by adopting a time difference method;
the frequency difference calculating module is used for obtaining frequency difference signals of the pipeline to be detected under different frequencies according to scattered waves received by the third ultrasonic sensor and the fourth ultrasonic sensor by adopting a frequency difference method;
and the flow velocity calculation module is used for determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the obtained time difference signal and frequency difference signal.
7. A method of downhole flow measurement error correction, comprising:
arranging an ultrasonic sensing device on the outer wall of the pipeline to be detected;
the ultrasonic sensing device transmits ultrasonic waves for at least one time and receives direct waves and scattered waves which are correspondingly generated in fluid of a pipeline to be detected;
obtaining time difference signals of the pipeline to be measured under different frequencies by adopting a time difference method according to the received direct waves;
obtaining frequency difference signals of the pipeline to be detected under different frequencies by adopting a frequency difference method according to the received scattered waves;
and determining the flow velocity of the fluid in the pipeline to be detected after error correction according to the obtained time difference signal and the frequency difference signal.
8. The method of correcting for downhole flow measurement error of claim 7, wherein providing an ultrasonic sensing device at an outer wall of the pipe under test comprises:
the outer wall of the pipeline to be measured is provided with a first ultrasonic sensor, a second ultrasonic sensor, a third ultrasonic sensor and a fourth ultrasonic sensor in an X shape, wherein the first ultrasonic sensor and the second ultrasonic sensor are located on the same inclined line, and the third ultrasonic sensor and the fourth ultrasonic sensor are located on the same inclined line.
9. The method of correcting errors in downhole flow measurement according to claim 8, wherein the ultrasonic sensing device transmits ultrasonic waves at least once and receives corresponding generated direct waves and scattered waves in the fluid of the pipe to be measured, comprising:
the first ultrasonic sensor transmits at least one ultrasonic wave with different frequencies to the direction of the second ultrasonic sensor, the second ultrasonic sensor receives a direct wave correspondingly generated in the fluid of the pipeline to be detected, and the fourth ultrasonic sensor receives a scattered wave correspondingly generated in the fluid of the pipeline to be detected;
the second ultrasonic sensor transmits at least one ultrasonic wave with different frequencies to the first ultrasonic sensor, the first ultrasonic sensor receives the direct wave correspondingly generated in the fluid of the pipeline to be measured, and the third ultrasonic sensor receives the scattered wave correspondingly generated in the fluid of the pipeline to be measured.
10. The method for correcting the flow measurement error in the downhole as claimed in claim 7, wherein said determining the flow rate of the fluid in the conduit to be measured after error correction based on the obtained time difference signal and the frequency difference signal comprises:
determining the weight of each effective signal according to the proportion of the effective time difference signals obtained by adopting a time difference method to the total effective signals under different frequencies and the proportion of the effective frequency difference signals obtained by adopting a frequency difference method to the total effective signals under different frequencies;
and calculating the flow velocity of the fluid in the pipeline to be detected after error correction according to the weighted effective signal.
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| CN115031797A (en) * | 2022-06-09 | 2022-09-09 | 中煤科工集团重庆研究院有限公司 | Method for eliminating transit time hopping influence by adopting double-frequency double-sound-track |
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2021
- 2021-11-24 CN CN202111403211.6A patent/CN114152317A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115031797A (en) * | 2022-06-09 | 2022-09-09 | 中煤科工集团重庆研究院有限公司 | Method for eliminating transit time hopping influence by adopting double-frequency double-sound-track |
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