An external flow measuring device, water distributor and flow measuring method for an oilfield separate injection well

Abstract

The application discloses an external flow measuring device for an oilfield separate injection well, which comprises a control circuit, a mounting rack, two ultrasonic probes, two sealing gaskets and two sealing joint assemblies. The mounting rack is provided with two mounting grooves. The ultrasonic probes are fixedly arranged in the mounting grooves. The sealing gaskets are arranged on the grooves of the mounting grooves. The sealing joint assemblies are sealingly connected with the mounting rack. The circuit of the ultrasonic probes is sealed by the sealing joint assemblies and led into the control circuit in the water distributor. Meanwhile, the ultrasonic probes are sealed in the mounting grooves by the sealing gaskets, so that the ultrasonic probes can be normally used in a high-temperature, high-pressure and high-corrosion environment without being easily damaged, and the sealing property of the measuring device is improved. The application further provides a water distributor for the oilfield separate injection well and a flow measuring method.

Description

Technical Field

[0001] This invention belongs to the field of oilfield water injection measurement technology, specifically relating to an external flow measurement device, water distributor, and flow measurement method for oilfield sub-injection wells. Background Technology

[0002] With the end of primary oil recovery in oilfields, stratified water injection is commonly used in secondary development. To achieve precise control of water injection volume in each layer, a flow meter needs to be continuously placed downhole to measure the injection volume. Currently, oilfields typically use orifice flow meters (based on differential pressure measurement) to measure the water injection volume in each layer. However, problems such as pressure sensor drift and orifice clogging occur during use, leading to inaccurate flow rate measurements and an inability to precisely control the water injection volume in each layer.

[0003] External ultrasonic flow meters are flow meters that use ultrasonic waves to measure flow rate. Their ultrasonic transmitting and receiving components (transducers) are installed outside the flow tube. Depending on the installation space, measurement range, and accuracy requirements, various installation methods such as Z, V, N, and W can be used. They also have significant advantages such as a wide range, no influence on fluid conditions, and minimal impact from fluid density and salinity, making them widely used in surface pipeline flow measurement. However, in oil and water wells under high temperature, high pressure, high salinity, and high corrosive well conditions, external ultrasonic flow meters lack sealing and are easily damaged when used in oil and water wells. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides an external flow measurement device, a water distributor, and a flow measurement method for oilfield injection wells. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] A first aspect of the present invention provides an external flow measurement device for oilfield injection wells, comprising a control circuit, a mounting frame, two ultrasonic probes, two sealing gaskets, and two sealing joint assemblies;

[0006] The mounting bracket has two mounting slots;

[0007] The two mounting slots are arranged alternately along the liquid flow direction; the surface of the slot opening is in contact with the flow pipe of the external water distributor;

[0008] The ultrasonic probe is fixedly installed in the mounting groove; the sealing gasket is installed on the opening of the mounting groove.

[0009] The sealing joint assembly is sealed to the mounting bracket and electrically connected to the ultrasonic probe and the control circuit.

[0010] The control circuit is fixedly installed inside the water distributor.

[0011] In one embodiment of the present invention, the control circuit includes: a power supply circuit, a drive circuit, a signal conditioning circuit, a time measurement circuit, a channel switching circuit, and a main control and communication circuit;

[0012] The main control and communication circuit is electrically connected to the power supply circuit, the time measurement circuit and the channel switching circuit.

[0013] The time measurement circuit is electrically connected to the power supply circuit, the drive circuit, and the signal conditioning circuit;

[0014] The signal conditioning circuit is electrically connected to the power supply circuit and the channel switching circuit; the driving circuit is electrically connected to the power supply circuit and the channel switching circuit.

[0015] The channel switching circuit is electrically connected to the power supply circuit and the two sealed connector assemblies. In one embodiment of the present invention, the signal conditioning circuit includes: a first-stage amplification and filtering circuit and an LC frequency-selective amplification circuit;

[0016] The LC frequency selective amplifier circuit includes: a comparator, a resistor, a capacitor, and an inductor;

[0017] The first-stage amplification and filtering circuit is connected to one end of the resistor; the positive input terminal of the comparator is grounded, and the negative input terminal is connected to the other end of the resistor; the two ends of the inductor are respectively connected to the negative input terminal and the output terminal of the comparator; the capacitor is connected in parallel with the inductor.

[0018] A second aspect of the present invention provides a water distributor for an oilfield injection well, comprising: an upper connector, a lower connector, a flow sub, a flow passage pipe, an outer protective pipe, and an external flow measurement device;

[0019] Both ends of the outer protective tube are sealed and fixedly connected to the upper connector and the lower connector, respectively; the flow meter is fixedly installed inside the outer protective tube;

[0020] The flow pipe is fixedly installed inside the outer protective pipe, and its two ends are connected to the upper connector and the lower connector;

[0021] The mounting bracket is fixedly connected to the flow tube, and the control circuit is fixedly installed inside the outer protective tube.

[0022] In one embodiment of the present invention, the flow meter is fixedly connected to the lower connector; the control circuit is fixedly connected to the upper connector.

[0023] A third aspect of the present invention provides a flow measurement method for an external flow measurement device for oilfield injection wells, applied to the external flow measurement device described in the first aspect of the present invention and the water distributor described in the third aspect, comprising the following steps:

[0024] Step 100: The control circuit excites the ultrasonic probe at the transmitting end to emit continuous detection ultrasonic waves and records the emission time.

[0025] Step 200: When the timing duration of the control circuit is equal to the preset start-up duration, the control circuit controls the ultrasonic probe at the receiving end to start working;

[0026] Step 300: The control circuit determines whether the voltage corresponding to the detected ultrasonic wave received by the ultrasonic probe at the receiving end is greater than the trigger bias voltage.

[0027] If the value is greater than 0, the trigger bias voltage is set to the measurement bias voltage, and the first receiving time is recorded; the measurement bias voltage value is 0.

[0028] Step 400: The control circuit sequentially determines whether the voltage corresponding to each of the multiple consecutive detection ultrasonic waves received by the ultrasonic probe at the receiving end is greater than the measurement bias voltage. If it is greater, the measurement reception time of each detection ultrasonic wave is recorded.

[0029] Step 500: The control circuit calculates multiple ultrasonic wave transmission times based on the transmission time, the first reception time, and each of the measured reception times.

[0030] Step 600: The control circuit controls the two ultrasonic probes to switch between transmitting and receiving ultrasonic waves.

[0031] Step 700: The control circuit repeats steps 100 to 500.

[0032] Step 800: The control circuit determines the flow rate of the liquid in the flow tube based on the multiple ultrasonic transmission times before and after switching between transmitting and receiving ultrasonic waves.

[0033] The beneficial effects of this invention are:

[0034] This invention seals the circuitry of the ultrasonic probe and leads it to the control circuitry within the water distributor using a sealing joint assembly. Simultaneously, a sealing gasket seals the ultrasonic probe within the mounting groove, enabling it to operate normally under high temperature, high pressure, and highly corrosive environments without significant damage. Furthermore, the mounting bracket ensures a tight fit with the flow pipe of the water distributor, further improving the sealing performance of the measuring device. This invention also provides a water distributor for oilfield injection wells and a flow measurement method.

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of an external flow measurement device for oilfield injection wells provided in an embodiment of the present invention;

[0037] Figure 2 This is a side view of an external flow measurement device for oilfield injection wells provided in an embodiment of the present invention;

[0038] Figure 3a This is a schematic diagram of the structure of a water distributor for an oilfield injection well provided in an embodiment of the present invention;

[0039] Figure 3b This is a schematic diagram of the ultrasonic transmitting and receiving structure of the ultrasonic probe provided in an embodiment of the present invention;

[0040] Figure 4 This is a circuit block diagram of an external flow measurement device for oilfield injection wells provided in an embodiment of the present invention;

[0041] Figure 5 This is a circuit diagram of the LC frequency-selective amplifier circuit provided in an embodiment of the present invention;

[0042] Figure 6 The amplitude-frequency characteristics of the signal LC bandpass circuit provided in this embodiment of the invention;

[0043] Figure 7 This is a schematic diagram illustrating measurement errors caused by highly dynamic fluids;

[0044] Figure 8 This is a schematic diagram of the measurement receiving time of an external flow measurement device for oilfield injection wells provided in an embodiment of the present invention.

[0045] Explanation of reference numerals in the attached figures:

[0046] 10-Mounting bracket; 11-Mounting slot; 20-Ultrasonic probe; 21-Probe base; 22-Piezoelectric ceramic plate; 30-Sealing gasket; 40-Sealing joint assembly; 50-Upper joint; 60-Lower joint; 70-Flow stub; 80-Flow tube; 90-Outer protective tube. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0048] Example 1

[0049] like Figure 1 , Figure 2 and Figure 3aAs shown, an external flow measurement device for oilfield injection wells includes a control circuit, a mounting bracket 10, two ultrasonic probes 20, two sealing gaskets 30, and two sealing joint assemblies 40. The mounting bracket 10 has two mounting slots 11.

[0050] Two mounting slots 11 are spaced apart sequentially along the liquid flow direction; the surface of the slot opening of the mounting slot 11 is in contact with the flow pipe 80 of the external water distributor; an ultrasonic probe 20 is fixedly installed inside the mounting slot 11. One ultrasonic probe 20 is located upstream of the liquid flow, and the other downstream, used to transmit ultrasonic waves for downstream and upstream measurements, respectively. A sealing gasket 30 is fixedly installed on the slot opening of the mounting slot 11. A sealing joint assembly 40 is sealed to the mounting frame 10 and electrically connected to the ultrasonic probe 20 and the control circuit. The control circuit is fixedly installed inside the water distributor. Two sealing joint assemblies 40 are respectively provided corresponding to the ultrasonic probe 20, used to lead out the circuit of each ultrasonic probe 20 and connect it to the control circuit. Specifically, the mounting frame 10 has a mounting through hole connecting the mounting slot 11 and the outside; one end of the sealing joint assembly 40 is sealed and installed in the mounting through hole; the lead wire of the ultrasonic probe 20 passes through the mounting through hole and is electrically connected to one end of the sealing joint assembly 40; the other end of the sealing joint assembly 40 is electrically connected to the control circuit. Each sealing connector assembly includes a positive terminal and a negative terminal.

[0051] In this embodiment, the control circuit controls the ultrasonic probe 20 to transmit and receive ultrasonic waves, processes the received signals, and realizes time difference data calculation and communication. The sealing joint assembly 40 is used to transmit the excitation signal and echo signal, ensuring the sealing performance of the electrical connection; the sealing gasket 30 is sandwiched between the flow pipe 80 and the mounting bracket 10, serving a sealing function. The surface of the mounting groove 11 of the mounting bracket 10 is in close contact with the flow pipe 80. The surface of the mounting bracket 10 matches the surface of the flow pipe 80. Since the surface of the flow pipe 80 is arc-shaped, the surface of the mounting bracket 10 is an arc-shaped surface that contacts and completely fits the arc-shaped surface of the flow pipe 80. After the mounting bracket 10 is installed on the flow pipe 80, it improves the sealing performance of the ultrasonic probe 20 within the mounting bracket 10, enabling the ultrasonic probe to be used normally in high temperature, high pressure, and highly corrosive environments without being easily damaged. The arc-shaped surface of the mounting bracket 10 is as follows: Figure 2 As shown, this is an arc surface with radius R.

[0052] Specifically, such as Figure 1 and Figure 3bAs shown, the ultrasonic probe 20 includes a probe base 21 and piezoelectric ceramic plates 22, both located within the mounting groove 11. The two piezoelectric ceramic plates 22 are mounted in a 45° V-shape to establish the ultrasonic channel. Specifically, the angle between the piezoelectric ceramic plates 22 and the direction of liquid flow is 45°, and the radiating surfaces of the two piezoelectric ceramic plates 22 are positioned opposite each other. The piezoelectric ceramic plates 22 are bonded to the probe base 21 using high-strength structural epoxy adhesive, enabling the mutual conversion of ultrasonic mechanical energy and electromagnetic energy of electrical signals. The probe base 21 is located between the sealing gasket 30 and the piezoelectric ceramic plates 22. A coupling agent is applied between the probe base 21 and the sealing gasket 30, which also prevents the coupling agent applied to the probe base 21 from being lost.

[0053] Furthermore, such as Figure 4 As shown, the control circuit includes: a power supply circuit, a drive circuit, a signal conditioning circuit, a time measurement circuit, a channel switching circuit, and a main control and communication circuit. The main control and communication circuit is electrically connected to the power supply circuit, the time measurement circuit, and the channel switching circuit. The time measurement circuit is electrically connected to the power supply circuit, the drive circuit, and the signal conditioning circuit; the signal conditioning circuit is electrically connected to the power supply circuit and the channel switching circuit; the drive circuit is electrically connected to the power supply circuit and the channel switching circuit; the channel switching circuit is electrically connected to the power supply circuit and two sealing connector assemblies 40. The channel switching circuit is electrically connected to the ultrasonic probe 20 through the sealing connector assembly 40.

[0054] In this embodiment, the power supply circuit provides suitable voltage power to other modules, ensuring the required voltage and current for each module to operate normally; the drive circuit generates a 1.3MHz excitation signal, which excites the ultrasonic probe 20 through the channel switching circuit, and simultaneously generates the ultrasonic transmission start time; the signal conditioning circuit receives the signal returned to the receiving ultrasonic probe 20 after propagation through the flow tube 80, and amplifies and filters it; the time measurement circuit performs analog-to-digital conversion through a comparator to obtain the ultrasonic transmission end time; the channel switching circuit switches the transmit / receive functions of the two ultrasonic probes 20; the main control and communication circuit performs excitation start / stop, channel switching, signal shielding, and other forward / backward flow measurement-related controls, calculates and filters the ultrasonic transmission time, and finally obtains the measurement result, and sends the relevant data of the measurement result to the main control circuit of the water distributor.

[0055] The flow measurement principle of the measuring device in this embodiment is as follows: The ultrasonic waves excited by the ultrasonic probe 20 propagate in the flowing fluid, and their velocity is superimposed on the fluid velocity: the velocity increases in the downstream direction and decreases in the upstream direction. The main control and communication circuit sends a signal to the time measurement circuit, which in turn sends a drive signal to the drive circuit. The drive circuit generates an excitation signal to excite the ultrasonic probes 20 at both the upstream and downstream locations to generate ultrasonic waves, which are then transmitted and received between them to perform downstream and upstream flow measurements. The channel switching circuit switches the transmit and receive states of the two ultrasonic probes 20 at the upstream and downstream locations to receive the corresponding echo signals. After processing by the signal conditioning circuit, the signal enters the time measurement circuit, which can obtain multiple downstream / upstream transmission time values ​​of the echoes (e.g., ...). Figure 8 The eight forward / backward transfer time values ​​are processed and filtered to obtain the final forward / backward time difference. Based on this difference and the calibration data of the flow measurement device (the correspondence between flow rate and time difference), the fluid velocity can be calculated, and thus the flow rate can be obtained.

[0056] In one feasible implementation, the core circuit of the time measurement circuit can employ a TOF sensor module, with a measurement accuracy of 15 ps, a measurement range of 500 ns to 4 ms, and a programmable bias voltage range of -256 mV to 250 mV for the internal comparator. It can measure up to 8 echo pulses. It features high precision, high stability, and high efficiency.

[0057] Preferably, such as Figure 5 As shown, the signal conditioning circuit includes: a first-stage amplification and filtering circuit and an LC frequency-selective amplification circuit. The LC frequency-selective amplification circuit includes: a comparator, a resistor R7, a capacitor C3, and an inductor L2.

[0058] The first-stage amplifier and filter circuit is connected to one end of resistor R7. The positive input terminal 5 of the comparator is grounded, and the negative input terminal 6 is connected to the other end of resistor R7. The two ends of inductor L2 are connected to the negative input terminal 6 and the output terminal 7 of the comparator, respectively. Capacitor C3 is connected in parallel with inductor L2.

[0059] In this embodiment, the first-stage amplification and filtering circuit performs preliminary filtering and amplification of the echo signal. Existing filtering and amplification circuits can be used, and will not be elaborated further here. The echo signal, amplified and filtered by the first-stage amplification and filtering circuit, then undergoes further amplification and filtering processing by an LC frequency-selective amplification circuit. The LC frequency-selective amplification circuit utilizes the impedance characteristics of LC parallel resonance to achieve high-Q amplification and filtering effects. From the measured data, as shown... Figure 6 As shown, high-frequency noise in the circuit is effectively filtered out, which effectively improves the stability of the measurement results.

[0060] The external flow measurement device in this embodiment has excellent sealing performance, can adapt to downhole flow measurement in high temperature, high pressure, high mineralization and high corrosive environments, is not easily damaged and has a long service life.

[0061] Example 2

[0062] like Figure 3a As shown, a water distributor for an oilfield injection well includes: an upper connector 50, a lower connector 60, a flow sub 70, a flow pipe 80, an outer protective pipe 90, and an external flow measurement device as described in Embodiment 1.

[0063] The outer protective tube 90 is sealed and fixedly connected to the upper connector 50 and the lower connector 60 at both ends, respectively. A flow meter 70 is fixedly installed inside the outer protective tube 90. A flow pipe 80 is fixedly installed inside the outer protective tube 90, with both ends connected to the upper connector 50 and the lower connector 60. The mounting bracket 10 is fixedly connected to the flow pipe 80, and the control circuit is fixedly installed inside the outer protective tube 90. The flow meter 70 is fixedly connected to the lower connector 60; the control circuit is fixedly connected to the upper connector 50. The flow pipe 80 is the fluid flow channel, the upper and lower connectors 60 facilitate fluid entry and exit, and the outer protective tube 90 connects the upper connector 50 and the lower connector 60, providing encapsulation and protection for other components. This water distributor is pressure-resistant up to 70 MPa, capable of withstanding high pressure and high temperature downhole, and enabling accurate flow measurement of highly dynamic fluids.

[0064] Example 3

[0065] A flow measurement method for an external flow measurement device in an oilfield injection well, applied to the external flow measurement device of Embodiment 1 and the water distributor of Embodiment 2, includes the following steps:

[0066] Step 100: The control circuit excites the ultrasonic probe 20 at the transmitting end to emit continuous detection ultrasonic waves and records the emission time.

[0067] Specifically, the main control and communication circuit sends a signal to the time measurement circuit, which in turn sends a drive signal to the drive circuit. The drive circuit generates an excitation signal to stimulate one of the ultrasonic probes 20 to produce detection ultrasonic waves. Simultaneously, the time measurement circuit starts timing and records the transmission time. The ultrasonic probe 20 that sends the detection ultrasonic waves is the transmitting end, and the ultrasonic probe 20 that receives the detection ultrasonic waves is the receiving end.

[0068] It should be noted that in existing technologies, the time-of-flight of ultrasound is measured by converting the received sinusoidal waveform into digital data using the piezoelectric effect of the ultrasonic probe. The accuracy and stability of this sinusoidal waveform largely determine the precision and stability of the test data. In practical applications, due to the uneven and unstable distribution of the fluid flow field, coupled with noise interference in the operating environment and electrical noise interference from the signal conditioning circuit, the received sinusoidal waveform often exhibits certain fluctuations and deviations. Furthermore, due to inconsistencies in the impedance characteristics, electromechanical coupling coefficients, and impedance matching of upstream and downstream transducers, as well as their electrical impedance matching, and the significant influence of temperature, zero-point errors and zero-point drift occur in the instrument, leading to substantial errors in the final measurement results.

[0069] To address the zero-point error and zero-point temperature drift of instruments, the common approach is to pre-measure and compensate using tables. However, in practical applications, due to the extremely short propagation time of sound waves, the measured data is highly sensitive to the phase and amplitude of the received waveform. Furthermore, the consistency of upstream and downstream transducers and the complexity of ultrasonic wave propagation characteristics result in poor repeatability of zero-point and zero-point temperature drift tests, making it impossible to obtain accurate compensation data. Therefore, the problem remains largely unresolved.

[0070] Because the ultrasonic waves propagate faster in the flow tube 80, they arrive earlier than those propagating from the fluid. Therefore, by measuring both echoes using the same method, the zero-point error and zero-temperature drift of this device can be eliminated. Thus, the zero-point error can be measured before step 100. The specific principle is as follows:

[0071] Assume that the time it takes for ultrasonic probe A to receive ultrasonic waves and convert them into electrical signals is T. A The time it takes for ultrasonic probe B to receive ultrasonic waves and convert them into electrical signals is T. B The ultrasonic wave travels through the 80mm flow tube for a time T. 钢 The transmission time of ultrasound through the fluid in the forward and reverse directions are T, respectively. 顺 T 逆 Therefore, the time for the ultrasonic wave to propagate through the flow tube 80 is: T A +T 钢 (B sends, A receives), T B +T 钢 (A sends, B receives), time difference: T A -T B Similarly, the time it takes for an ultrasonic wave to travel through a fluid is: T A +T 逆 (B sends, A receives), T B +T 顺 (A sends, B receives), the ultrasonic wave transmission time is T. A +T 钢 +T逆 (B sends, A receives), T B +T 钢 +T 顺 (A transmits, B receives), the time difference for ultrasonic wave transmission is: T A -T B +T 逆 -T 顺 .

[0072] During the zero-point error measurement phase, the ultrasonic waves propagating in the flow tube 80 arrive before the ultrasonic waves propagating from the fluid. When ultrasonic probe A sends out ultrasonic waves, the first wave received by ultrasonic probe B is the ultrasonic wave propagating through the flow tube 80, and T is measured. B +T 钢 Then, the receiving and transmitting ultrasonic probes are switched to measure the first wave and obtain T. A +T 钢 The zero-point value was measured as: T A -T B Then the subsequent flow measurement results (T) can be used. A -T B +T 逆 -T 顺 By compensating for this, the zero-position error can be eliminated, and the true time difference of ultrasonic waves propagating in the fluid with and against the current can be obtained.

[0073] Of course, during the zero-point error measurement phase, multiple T values ​​can be continuously measured starting from the first wave. B +T 钢 To calculate the average value and continuously measure multiple T values. A +T 钢 By calculating the average value, a more accurate zero-point value can be obtained. After the zero-point error measurement is completed, the formal flow measurement begins.

[0074] Step 200: When the timing duration of the control circuit is equal to the preset start-up duration, the control circuit controls the ultrasonic probe 20 at the receiving end to start working; the preset start-up duration is the difference between the transmission time of the detected ultrasonic wave in the static fluid in the flow tube 80 and 2.875T, where T is the period of the detected ultrasonic wave.

[0075] Specifically, when the timing duration of the time measurement circuit equals the preset start-up duration, the time measurement circuit sends a drive signal to the drive circuit, and the drive circuit controls the ultrasonic probe 20 of the receiving section to start working, ready to receive and detect ultrasonic waves.

[0076] The preset startup duration is set before the instrument is lowered into the well. The time point reached after the preset startup duration is the shielding time. If the shielding time is unreasonable, it will lead to "over-cycle triggering," resulting in measurement errors. Figure 8As shown, by setting the shielding time DEVEL1 close to the maximum amplitude of the echo envelope, the first_wave is triggered as soon as the shielding time is reached, completely eliminating the problem of false triggering by noise or interference echoes. Furthermore, the program automatically adjusts the shielding time DEVEL1 (at the same time as the first_wave) so that the time difference between it and the transmission time of the detection ultrasonic wave in the static fluid in the flow tube 80 is 2.875T, completely eliminating the "over-cycle triggering" phenomenon caused by the attenuation of the echo signal.

[0077] Step 300: The control circuit determines whether the voltage corresponding to the detected ultrasonic wave received by the ultrasonic probe 20 at the receiving end is greater than the trigger bias voltage. The trigger bias voltage is a relatively high voltage value, approximately 100mV.

[0078] In existing technologies, when the fluid is in a highly dynamic state, such as with backflow or turbulence, or when there is contamination on the inner wall of the flow tube, the echo signal is significantly attenuated, even with the same bias voltage V. f In other words (e.g.) Figure 7 As shown), the forward and reverse currents may differ by one or more sine wave cycles, triggering a measurement error and causing V to be affected. f Setting the bias voltage too low makes the system more susceptible to environmental interference and false triggering by noise. However, this step solves the problem by setting a higher bias voltage for echo locking first, and then setting the bias voltage to 0 before triggering. This enables high-dynamic fluid measurement, and even backflow can be measured.

[0079] If the value is greater than the specified value, the trigger bias voltage is set to the measurement bias voltage, and the first reception time is recorded; the measurement bias voltage value is 0. The detection ultrasonic wave corresponding to the first reception time is the first detection ultrasonic wave at the start of the measurement.

[0080] If the voltage is less than the trigger bias voltage, the receiving ultrasonic probe 20 continues to receive the detection ultrasonic waves, and the control circuit continues to judge until the voltage corresponding to the received detection ultrasonic waves is greater than the trigger bias voltage.

[0081] The transmitting ultrasonic probe 20 emits continuous detection ultrasonic waves. After a preset time, the receiving ultrasonic probe 20 starts working. When the receiving ultrasonic probe 20 receives the detection ultrasonic waves, it converts them into electrical signals and inputs them into the signal conditioning circuit. The signal conditioning circuit amplifies and filters the signal, and then inputs it into the main control and communication circuit through the time measurement circuit. The main control and communication circuit determines whether the voltage corresponding to the first detection ultrasonic wave received by the receiving ultrasonic probe 20 is greater than the trigger bias voltage of the time measurement circuit. If it is greater, the received detection ultrasonic wave is the first wave, and the measurement starts with the first detection ultrasonic wave. The trigger bias voltage is set as the measurement bias voltage, and the first reception time is recorded. The measurement bias voltage value is 0.

[0082] Step 400: The control circuit sequentially determines whether the voltage corresponding to each of the multiple consecutive detection ultrasonic waves received by the ultrasonic probe 20 at the receiving end is greater than the measurement bias voltage. If it is greater, the measurement reception time of each detection ultrasonic wave is recorded.

[0083] Specifically, the ultrasonic probe 20 at the receiving end continuously receives each subsequent ultrasonic wave starting from the first ultrasonic wave. The main control and communication circuit sequentially determines whether the voltage corresponding to each subsequent ultrasonic wave received by the ultrasonic probe 20 at the receiving end is greater than the measurement bias voltage. If it is greater, the measurement reception time of each ultrasonic wave is recorded.

[0084] Step 500: The control circuit calculates multiple ultrasonic wave transmission times based on the transmission time, the first reception time, and each measurement reception time. The ultrasonic wave transmission time can be either downstream or upstream. If the upstream ultrasonic probe 20 is driven first to transmit the detection ultrasonic wave, it is the downstream transmission time; otherwise, it is the upstream transmission time. The difference between the first reception time and the transmission time is the ultrasonic wave transmission time of the first detection ultrasonic wave. The difference between each measurement reception time and the previous measurement reception time is the ultrasonic wave transmission time of each detection ultrasonic wave. Specifically, the difference between the measurement reception time of the second detection ultrasonic wave and the first reception time is the ultrasonic wave transmission time of the second detection ultrasonic wave.

[0085] Preferably, the main control and communication circuit continuously records the measurement reception times HIT1-HIT8 of eight waves, starting with the first detected ultrasonic wave. For example... Figure 8 As shown, for example, the downstream transmission time is recorded as 8 measurement reception times, and the upstream transmission time is also recorded as 8 measurement reception times. This yields 8 forward and reverse time difference values, which are the ultrasonic transmission time differences (the ultrasonic transmission time of each echo is the current measurement reception time minus the measurement reception time of the previous echo). The main control and communication circuits then perform amplitude limiting filtering, speed limiting filtering, median filtering, and smoothing filtering in the software program to obtain stable and accurate measurement results.

[0086] Step 600: The control circuit controls the two ultrasonic probes 20 to switch between transmitting and receiving ultrasonic waves. The main control and communication circuit controls the channel switching circuit to switch the transmission and reception functions of the two ultrasonic probes 20.

[0087] Step 700: Repeat steps 100 to 500. Specifically, if the upstream ultrasonic probe 20 is first excited to emit detection ultrasonic waves, then the downstream ultrasonic probe 20 is the receiving end for downstream measurement. After the downstream measurement is completed, the downstream ultrasonic probe 20 is switched to emit detection ultrasonic waves, and the upstream ultrasonic probe 20 is the receiving end for upstream measurement. The above steps are then performed for countercurrent measurement.

[0088] In step 800, the control circuit determines the flow rate of the liquid in the flow pipe 80 based on the multiple ultrasonic wave transmission times before and after switching between transmitting and receiving ultrasonic waves. Specifically, the main control and communication circuit calculates the flow rate. For example, it first calculates the downstream transmission time, then calculates the upstream transmission time after switching. The difference between the upstream and downstream transmission times can be used to calculate the fluid velocity, and further calculations can yield the flow rate.

[0089] This embodiment achieves high-precision, high-stability non-contact flow measurement of downhole fluids under high dynamic conditions.

[0090] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0091] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0092] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0093] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0094] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0095] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A flow measurement method for an external flow measurement device in an oilfield injection well, characterized in that, It is applied to external flow measurement devices and water distributors. The external flow measurement device includes a control circuit, a mounting bracket (10), two ultrasonic probes (20), two sealing gaskets (30), and two sealing joint assemblies (40). The mounting bracket (10) has two mounting slots (11); The two mounting slots (11) are arranged alternately along the liquid flow direction; the surface of the slot opening of the mounting slot (11) is in contact with the flow pipe (80) of the external water distributor, the surface of the flow pipe (80) is an arc surface, and the surface of the mounting bracket (10) is an arc surface that contacts and is completely in contact with the arc surface of the flow pipe (80); The ultrasonic probe (20) is fixedly installed in the mounting groove (11). The ultrasonic probe (20) includes a probe base (21) and a piezoelectric ceramic plate (22) located in the mounting groove (11). The piezoelectric ceramic plates (22) of the two ultrasonic probes (20) form an angle of 45° with the direction of liquid flow in the flow tube (80), and the radiating surfaces of the two piezoelectric ceramic plates (22) are arranged opposite to each other to realize the establishment of the ultrasonic channel. The sealing gasket (30) is disposed on the groove of the mounting groove (11); The sealing joint assembly (40) is sealed to the mounting bracket (10) and electrically connected to the ultrasonic probe (20) and the control circuit; The control circuit is fixedly installed inside the water distributor; The water distributor includes an upper connector (50), a lower connector (60), a flow short section (70), a flow pipe (80), an outer protective pipe (90), and the external flow measurement device; The two ends of the outer protective tube (90) are sealed and fixedly connected to the upper connector (50) and the lower connector (60) respectively; The flow section (70) is fixedly installed inside the outer protective tube (90); The flow pipe (80) is fixedly installed inside the outer protective pipe (90), and its two ends are connected to the upper connector (50) and the lower connector (60); The mounting bracket (10) is fixedly connected to the flow pipe (80), and the control circuit is fixedly installed inside the outer protective tube (90); The two ultrasonic probes (20) are ultrasonic probe A and ultrasonic probe B, respectively. It is assumed that the time taken for ultrasonic probe A to receive ultrasonic waves and convert them into electrical signals is T. A The ultrasonic probe B receives ultrasonic waves and converts them into electrical signals in a time T. B The ultrasonic wave travels through the flow tube (80) for a time T. 钢 The transmission time of ultrasound through the fluid in the forward and reverse directions are T, respectively. 顺 T 逆 ; The method includes the following steps: Ultrasonic probe A sends out ultrasonic waves, and when ultrasonic probe B receives the first wave, it is the ultrasonic wave propagating through the flow tube (80), and T is measured. B +T 钢 Then, the receiving and transmitting ultrasonic probes are switched to measure the first wave and obtain T. A +T 钢； Zero position measured: T A -T B ; The flow measurement results of the external flow measurement device are compensated, and the flow measurement result is: T A -T B +T 逆 -T 顺 ; In the zero-position error measurement phase, multiple T values ​​are continuously measured starting from the first wave. B +T 钢 To calculate the average value and continuously measure multiple T values. A +T 钢 To calculate the average value, a more accurate zero-point value is obtained; Step 100: The control circuit excites the ultrasonic probe (20) at the transmitting end to emit continuous detection ultrasonic waves and records the emission time. Step 200: When the timing duration of the control circuit is equal to the preset start-up duration, the control circuit controls the ultrasonic probe (20) at the receiving end to start working. Step 300: The control circuit determines whether the voltage corresponding to the detected ultrasonic wave received by the ultrasonic probe (20) at the receiving end is greater than the trigger bias voltage. If the value is greater than 0, the trigger bias voltage is set to the measurement bias voltage, and the first receiving time is recorded; the measurement bias voltage value is 0. Step 400: The control circuit sequentially determines whether the voltage corresponding to each of the multiple consecutive detection ultrasonic waves received by the ultrasonic probe (20) at the receiving end is greater than the measurement bias voltage. If it is greater, the measurement reception time of each detection ultrasonic wave is recorded. Step 500: The control circuit calculates multiple ultrasonic wave transmission times based on the transmission time, the first reception time, and each of the measured reception times. Step 600: The control circuit controls the two ultrasonic probes (20) to switch between transmitting and receiving ultrasonic waves. Step 700: The control circuit repeats steps 100 to 500. In step 800, the control circuit determines the flow rate of the liquid in the flow tube (80) based on the multiple ultrasonic transmission times before and after switching between transmitting and receiving ultrasonic waves.

2. The external flow measurement method for oilfield injection wells according to claim 1, characterized in that, The control circuit includes: a power supply circuit, a drive circuit, a signal conditioning circuit, a time measurement circuit, a channel switching circuit, and a main control and communication circuit; The main control and communication circuit is electrically connected to the power supply circuit, the time measurement circuit and the channel switching circuit. The time measurement circuit is electrically connected to the power supply circuit, the drive circuit, and the signal conditioning circuit; The signal conditioning circuit is electrically connected to the power supply circuit and the channel switching circuit. The driving circuit is electrically connected to the power supply circuit and the channel switching circuit. The channel switching circuit is electrically connected to the power supply circuit and the two sealing connector assemblies (40).

3. The external flow measurement method for oilfield injection wells according to claim 2, characterized in that, The signal conditioning circuit includes: a first-stage amplification and filtering circuit and an LC frequency-selective amplification circuit; The LC frequency selective amplifier circuit includes: a comparator, a resistor, a capacitor, and an inductor; The first-stage amplification and filtering circuit is connected to one end of the resistor; the positive input terminal of the comparator is grounded, and the negative input terminal is connected to the other end of the resistor; the two ends of the inductor are respectively connected to the negative input terminal and the output terminal of the comparator; the capacitor is connected in parallel with the inductor.

4. The external flow measurement method for oilfield injection wells according to claim 1, characterized in that, The flow meter (70) is fixedly connected to the lower connector (60); The control circuit is fixedly connected to the upper connector (50).

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