Design method and system for dual-band impedance matching circuit of acoustic wave transducer while drilling with aftershock attenuation characteristic

Abstract

The invention discloses a method and a system for designing a dual-band impedance matching circuit of a while-drilling acoustic transducer with a residual vibration attenuation characteristic. The system comprises an excitation circuit, a residual vibration attenuation control MOS (Metal Oxide Semiconductor) tube, an n-shaped dual-band impedance matching network, a boosting transformer and the while-drilling transducer. The method comprises the following steps: establishing an electromechanical coupling equivalent circuit according to the size and material parameters of the transducer while drilling, and accessing an n-shaped double-frequency impedance matching network; performing target optimization on the impedance function in the frequency band of the circuit model by using an adaptive algorithm, and outputting an n-type dual-frequency impedance matching network element parameter; and welding the calculated dual-frequency impedance matching network and the residual vibration attenuation control MOS tube to assemble a module system. An efficient monopole mode (10-14 kHz) and a quadrupole mode (2-4 kHz) can be achieved only through one set of transducers, more sound wave energy can be radiated, then the sound source intensity of the acoustic logging-while-drilling instrument is enhanced, and residual vibration interference of excitation signals is effectively restrained.

Description

Technical Field

[0001] The present invention relates to a circuit system and a design method, and in particular to a dual-band impedance matching circuit design method and system for a while-drilling acoustic wave transducer with residual vibration attenuation characteristics. Background Art

[0002] The acoustic logging instrument while drilling is a key equipment for deep oil and gas exploration. Its operation process is accompanied by the interference of drill collar waves and drilling noise, which seriously reduces the signal-to-noise ratio of the instrument. Enhancing the radiation energy is an important way to improve this problem. The main working modes of the current transducer while drilling are: monopole mode (10-14kHz) and quadrupole mode (2-4kHz). In order to stimulate effective signals in both frequency bands at the same time, the current acoustic logging instrument while drilling is often installed with two sets of sound source systems, a set of monopole transducers and a set of quadrupole transducers. Since the switching of the two sets of transducers needs to be controlled, this solution leads to an increase in the number of electronic compartment components and transducers of the instrument, and the cost of instrument research and development is high. In addition, there are few dual-band impedance matching technologies that can meet the requirements of both monopole mode and quadrupole mode.

[0003] Chinese patent application CN201911275168.2 provides a broadband impedance matching method for an acoustic transducer, but it is difficult to apply to the dual-frequency excitation mode of a downhole acoustic transducer and the transducer equivalent circuit modeling fails to consider the electromechanical coupling problem. Chinese patent application CN201910146732.4 provides an internal wiring method and an installation method for a transducer. The structure is loaded and the low-frequency signal generated has a frequency of 5.5kHz. It fails to effectively enhance the radiation energy of the transducer signal. The generated low-frequency signal has limited effect and is difficult to meet the lower frequency quadrupole mode. It does not have dual-band excitation characteristics and is only a simple low-frequency transducer.

[0004] In summary, the development of a dual-band excitation characteristic LWD transducer impedance matching network circuit can effectively enhance the instrument detection performance, reduce the number of transducers used, and reduce the instrument development cost. The LWD transducer is a capacitive element. When the excitation signal ends, some residual energy will remain in itself and the step-up transformer coil, causing the transducer to vibrate, which interferes with the signal acquisition end. The invention patents CN214473921U and CN114415162A both use soft methods such as algorithm optimization of the excitation signal to attenuate the residual vibration of the ultrasonic transducer. Compared with the hardware design method of directly discharging energy from the source, the efficiency of attenuating the residual vibration is low, and it cannot effectively solve the problem of discharging the residual energy of the transducer and transformer, and the residual vibration attenuation effect is limited. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a novel dual-band impedance matching circuit design method and module with residual vibration attenuation characteristics, which can simultaneously enhance the excitation efficiency of the monopole and quadrupole modes of the drilling transducer and reduce the residual vibration tail signal of the transducer.

[0006] Technical solution: The dual-band impedance matching circuit system of a drilling acoustic wave transducer with aftershock attenuation characteristics described in the present invention comprises an excitation circuit, a MOS tube for aftershock attenuation control, a Π-type dual-frequency impedance matching network, a step-up transformer and a drilling acoustic wave transducer. The inductor LS in the Π-type dual-frequency impedance matching network is connected in series with the secondary of the step-up transformer. The D pole of the MOS tube is connected to the upper end of the capacitor CP0 in the Π-type dual-frequency impedance matching network and then connected in series with the matching inductor LP. The matching inductor LP is connected to the upper end of the matching capacitor CP1 and then connected in series with the matching inductor LS. The S pole is connected to the excitation circuit GND, the G pole is connected to the main control pulse of the excitation control circuit, the high-voltage output end of the excitation circuit is connected in parallel with the capacitor of the Π-type matching network, and the positive and negative electrodes of the drilling acoustic wave transducer are connected to the secondary of the pulse transformer.

[0007] The design method of the above system is as follows:

[0008] (1) According to the size and material parameters of the drilling transducer, an electromechanical coupling equivalent circuit is established and connected to a π-type dual-frequency impedance matching network;

[0009] (2) Using an adaptive algorithm to optimize the impedance function within the frequency band of the circuit model, and outputting the parameters of the Π-type dual-frequency impedance matching network components;

[0010] (3) The calculated dual-frequency impedance matching network and the residual vibration attenuation control MOS tube are welded to assemble into a module system.

[0011] Specifically,

[0012] 1. First, the electromechanical coupling equivalent circuit of the drilling transducer is constructed according to its size and material parameters, where: Z11, Z12, and Z13 represent the equivalent impedance of the ceramic sheet-1 inside the drilling transducer, Z22, Z21, and Z23 represent the equivalent impedance of the external packaging material of the drilling transducer, and Z31, Z32, and Z33 represent the equivalent impedance of the ceramic sheet-2 inside the drilling transducer. All parts in the equivalent circuit model are T-type circuit structures, and the impedances of the two piezoelectric ceramics Z13 and Z33 are connected in series with the equivalent transformer. LP, LS, CP0, and CP1 are the parameters of the Π-type dual-frequency impedance matching network components to be calculated, respectively, and C0 is the static capacitance of the transducer. For the convenience of calculation, the impedance matching network is located on both sides of the piezoelectric ceramic sheet.

[0013] Z 11 =Z 12 =Z 31 =Z 32= jAZ0 tan(βT1 / 2) (1)

[0014]

[0015] Z 21 = Z 22 = jρCS tan(KT2 / 2) (3)

[0016]

[0017] In the formula, D = (Z 13 + Z 11 )(Z 23 + Z 31 )(Z 33 + Z 32 )(Z 11 Z 12 + Z 11 Z 13 + Z 11 Z 21 + Z 12 Z 13 + Z 13 Z 21 ), E = ((Z 13 + Z 12 + Z 21 + Z 23 )Z 33 +(Z 22 + Z 23 + Z 31 )(Z 12 + Z 13 + Z 21 ))Z 32 + Z 33 (Z 22 + Z 23 + Z 31 )(Z 12 + Z 13 + Z 21 ), F = ((Z 12 + Z 21 + Z 23 )Z 33 +(Z 22 + Z 23 + Z 31 )(Z 12 + Z 21 ))Z 32 + Z 33 (Z 22 + Z 23 + Z 31 )(Z 12 + Z 21 ).

[0018] T1 is the surface area of ​​the piezoelectric ceramic, T2 is the thickness of the piezoelectric ceramic, S is the surface area of ​​the packaging material, K is the wave number, j is a complex number, C is the material wave velocity, p is the piezoelectric material density, and p2 is the packaging material density.

[0019] 2. According to the adaptive algorithm, the impedance expression function (Formula 5) of the entire equivalent circuit is locally optimized so that the real part of the impedance function is close to the output resistance of the excitation circuit and the imaginary part is close to 0. First, the target frequency band is set, and then the dynamic weight coefficient is set according to the matching requirements to automatically track the average impedance within the frequency band of the circuit model. When the local optimal convergence is met, the parameters of the Π-type impedance matching network components are output.

[0020] 3. The designed Π-type dual-frequency impedance matching network inductor LS is connected in series with the secondary of the pulse boost transformer, the MOS tube D pole is connected to the upper end of the capacitor CP0 in the dual-frequency impedance matching network and then connected in series with the matching inductor LP, the matching inductor LP is connected to the upper end of the matching capacitor CP1 and then connected in series with the matching inductor LS, the S pole is connected to the excitation circuit GND, the G pole is connected to the main control pulse of the excitation control circuit, the high-voltage output end of the excitation circuit is connected in parallel with the matching network capacitor, the positive and negative electrodes of the drilling transducer are connected to the secondary of the pulse transformer, the pulse transformer of the module of the present invention has a turns ratio of 1:5-20, when the excitation signal ends, the excitation circuit pulls the MOS tube G pole up to 15V and maintains it for 5-10ms and then pulls it down to a low level, the connection diagram is as shown Figure 3 shown.

[0021] The design process of the dual-band residual vibration attenuation impedance matching circuit module is as follows: Figure 4 As shown, firstly, the electromechanical coupling equivalent circuit proposed in the present invention is constructed according to the size and material parameters of the while drilling transducer, and then the impedance function in the circuit model is optimized by the adaptive algorithm proposed in the present invention. Finally, the calculated dual-frequency impedance matching network element and the residual vibration attenuation control MOS tube are welded on the PCB circuit and assembled into a module for application.

[0022] In order to facilitate instrument installation and large-scale application, the module shell material of the present invention is made of hard aluminum. After the matching components, step-up transformer and MOS tube are welded on the PCB circuit board, they are fixed in the hard aluminum shell with hexagonal screws. The internal cavity is extruded and filled with 3140 silicone to fix the components and prevent the internal circuit from loosening and short circuit. The module structure diagram is shown in the figure. Figure 5 shown.

[0023] The present invention designs a dual-band impedance matching circuit design method and module with residual vibration attenuation characteristics, which can effectively enhance the excitation signal energy of the drilling acoustic wave transducer in the monopole and quadrupole modes and attenuate the residual vibration interference signal. A transducer electromechanical coupling equivalent circuit combined with an impedance matching network is proposed. In order to facilitate calculation, the impedance matching network is connected to the equivalent impedance of the piezoelectric ceramic Z33 through an equivalent transformer in the equivalent circuit; an independently innovative adaptive algorithm is used to target the impedance function of the circuit model; the present invention discharges the entire loop through a MOS tube after the transducer completes the excitation, and the D pole of the MOS tube is connected in series to the upper end of the dual-frequency impedance matching network CP0, the S pole is grounded, and the G pole is connected to the excitation circuit control signal, and is welded on the PCB circuit together with the impedance matching element, and a parallel pulse boost transformer is connected to form a module. The four wires on the left are respectively the excitation voltage +, the residual vibration attenuation control signal, GND, and the excitation voltage -, and the two wires on the right are respectively the transducer high voltage + and the transducer high voltage -.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] Compared with conventional acoustic logging while drilling transmission systems, the present invention uses only one set of transducers to achieve efficient monopole mode (10-14kHz) and quadrupole mode (2-4kHz) working frequency bands, can radiate more acoustic wave energy to enhance the sound source strength of the acoustic logging while drilling instrument and effectively suppress the residual vibration interference of the excitation signal. The dual-band impedance matching circuit module with residual vibration attenuation characteristics proposed by the present invention can be used to perform longitudinal wave measurement of the monopole mode and shear wave measurement of the dipole mode using a set of transducers, effectively reducing the instrument research and development and manufacturing costs. The impedance characteristics of the electromechanical coupling model of the transducer of the present invention are more consistent with the actual transducer impedance characteristics, and are integrated into the impedance matching network, and an adaptive algorithm is used to optimize the impedance function, which is more accurate and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the calculation model of the dual-frequency impedance matching circuit of the transducer;

[0027] Figure 2 It is the flow chart of dual-frequency impedance matching adaptive algorithm;

[0028] Figure 3 It is a schematic diagram of the structure of a dual-band aftershock attenuation impedance matching circuit;

[0029] Figure 4 Design a flow chart for the module of the present invention;

[0030] Figure 5 It is a schematic diagram of the circuit module structure of the present invention;

[0031] Figure 6 For active power comparison test;

[0032] Figure 7 This is a test comparison of the excitation signal aftershock tailing interference. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further described below.

[0034] The circuit system described in this embodiment is designed as follows:

[0035] 1. First, construct its electromechanical coupling equivalent circuit according to the size and material parameters of the while drilling transducer, where: Z11, Z12, Z13 represent the equivalent impedance of the ceramic sheet-1 inside the while drilling transducer, Z22, Z21, Z23 represent the equivalent impedance of the external packaging material of the while drilling transducer, Z31, Z32, Z33 represent the equivalent impedance of the ceramic sheet-2 inside the while drilling transducer, and each part in the equivalent circuit model is a T-type circuit structure, and the impedances Z13 and Z33 of the two piezoelectric ceramics are connected in series with the equivalent transformer. LP, LS, CP0, CP1 are the parameters of the Π-type dual-frequency impedance matching network components to be calculated, C0 is the static capacitance of the transducer, and for the convenience of calculation, the impedance matching network is located on both sides of the piezoelectric ceramic sheet. Figure 1 .

[0036] Z 11 =Z 12 =Z 31 =Z 32 = jAZ0 tan(βT1 / 2) (1)

[0037]

[0038] Z 21 =Z 22 =jρCS tan(KT2 / 2) (3)

[0039]

[0040] In the formula, D=(Z 13 +Z 11 )(Z 23 +Z 31 )(Z 33 +Z 32 )(Z 11 Z 12 +Z 11 Z 13 +Z 11 Z 21 +Z 12 Z 13 +Z 13 Z 21 ), E=((Z13 +Z 12 +Z 21 +Z 23 )Z 33 +(Z 22 +Z 23 +Z 31 )(Z 12 +Z 13 +Z 21 ))Z 32 +Z 33 (Z 22 +Z 23 +Z 31 )(Z 12 +Z 13 +Z 21 ), F=((Z 12 +Z 21 +Z 23 )Z 33 +(Z 22 +Z 23 +Z 31 )(Z 12 +Z 21 ))Z 32 +Z 33 (Z 22 +Z 23 +Z 31 )(Z 12 +Z 21 ).

[0041] T1 is the surface area of ​​the piezoelectric ceramic, T2 is the thickness of the piezoelectric ceramic, S is the surface area of ​​the packaging material, K is the wave number, j is a complex number, C is the material wave velocity, p is the piezoelectric material density, and p2 is the packaging material density.

[0042] 2. According to the adaptive algorithm, the impedance expression function (Formula 5) of the entire equivalent circuit is locally optimized so that the real part of the impedance function is close to the output resistance of the excitation circuit and the imaginary part is close to 0. First, the target frequency band is set, and then the dynamic weight coefficient is set according to the matching requirements to automatically track the average impedance within the frequency band of the circuit model. When the local optimal convergence is met, the parameters of the Π-type impedance matching network components are output. Figure 2 .

[0043] 3. The designed Π-type dual-frequency impedance matching network inductor LS is connected in series with the secondary of the pulse boost transformer, the MOS tube D pole is connected to the upper end of the capacitor CP0 in the dual-frequency impedance matching network and then connected in series with the matching inductor LP, the matching inductor LP is connected to the upper end of the matching capacitor CP1 and then connected in series with the matching inductor LS, the S pole is connected to the excitation circuit GND, the G pole is connected to the main control pulse of the excitation control circuit, the high-voltage output end of the excitation circuit is connected in parallel with the matching network capacitor, the positive and negative electrodes of the drilling transducer are connected to the secondary of the pulse transformer, the pulse transformer of the module of the present invention has a turns ratio of 1:5-10, when the excitation signal ends, the excitation circuit pulls the MOS tube G pole up to 15V and maintains it for 5-10ms and then pulls it down to a low level, the connection diagram is as shown Figure 3 shown.

[0044] The design process of the dual-band residual vibration attenuation impedance matching circuit module is as follows: Figure 4 As shown, firstly, the electromechanical coupling equivalent circuit proposed in the present invention is constructed according to the size and material parameters of the while drilling transducer, and then the impedance function in the circuit model is optimized by the adaptive algorithm proposed in the present invention. Finally, the calculated dual-frequency impedance matching network element and the residual vibration attenuation control MOS tube are welded on the PCB circuit and assembled into a module for application.

[0045] In order to facilitate instrument installation and large-scale application, the module shell material of the present invention is made of hard aluminum. After the matching components, step-up transformer and MOS tube are welded on the PCB circuit board, they are fixed in the hard aluminum shell with hexagonal screws. The internal cavity is extruded and filled with 3140 silicone to fix the components and prevent the internal circuit from loosening and short circuit. The module structure diagram is shown in the figure. Figure 5 shown.

[0046] The details are as follows:

[0047] First, according to the size and material parameters of the drilling transducer, for example, the overall height of the transducer is 120mm, the height of the two piezoelectric ceramics is 52mm, the inner diameter is 75mm, the outer diameter is 80mm, the arc is 88°, the material is PZT-4, the distance from the bottom and both ends of the packaging material is 2mm, and the packaging material is selected with a Young's modulus of 10 9 Pa, Poisson's ratio is 0.32, density is 1500kg / m 3 , epoxy resin with an arc of 90°, and obtain its electromechanical coupling equivalent circuit model, and combine it with the dual-frequency impedance matching network. Then, based on this circuit, the adaptive algorithm is used to optimize the impedance function of the target frequency band. After obtaining the specific component parameters, it is assembled into a module together with the residual vibration control MOS tube and the transformer. Figure 6 As shown, after adopting the method and module proposed in the present invention, it can be seen that within the frequency band of the monopole and quadrupole modes, the active power of the transducer is greatly improved, with an average increase of 3.2 times; Figure 7It is shown that after adopting the method and module proposed in the present invention, the emission voltage is increased by two times and the waveform is smoothed, the generation of spike pulses is suppressed, and the residual vibration tail amplitude of the transducer excitation signal is attenuated by 75%.

[0048] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A dual-band impedance matching circuit system for a while-drilling acoustic wave transducer with residual vibration attenuation characteristics, characterized in that: The invention comprises an excitation circuit, a residual vibration attenuation control MOS tube, a Π-type dual-frequency impedance matching network, a boost transformer and a while-drilling transducer. The inductor LS in the Π-type dual-frequency impedance matching network is connected in series with the secondary of the boost transformer. The D pole of the MOS tube is connected to the upper end of the capacitor CP0 in the Π-type dual-frequency impedance matching network and then connected in series with the matching inductor LP. The matching inductor LP is connected to the upper end of the matching capacitor CP1 and then connected in series with the matching inductor LS. The S pole is connected to the excitation circuit GND, the G pole is connected to the main control pulse of the excitation control circuit, the high-voltage output end of the excitation circuit is connected in parallel with the capacitor of the Π-type matching network, and the positive and negative electrodes of the while-drilling transducer are connected to the secondary of the pulse transformer.

2. The dual-band impedance matching circuit system of a while drilling acoustic wave transducer with aftershock attenuation characteristics according to claim 1 is characterized in that: The turn ratio of the step-up transformer is 1:5-20.

3. The design method of the dual-band impedance matching circuit system of the while drilling acoustic wave transducer with aftershock attenuation characteristics according to claim 1 or 2, characterized in that: The steps include: (1) According to the size and material parameters of the drilling transducer, an electromechanical coupling equivalent circuit is established and connected to a π-type dual-frequency impedance matching network; (2) Using an adaptive algorithm to optimize the impedance function within the frequency band of the circuit model, and outputting the parameters of the Π-type dual-frequency impedance matching network components; (3) The calculated dual-frequency impedance matching network and the residual vibration attenuation control MOS tube are welded to assemble into a module system.

4. The design method of the dual-band impedance matching circuit system of the acoustic wave transducer while drilling with aftershock attenuation characteristics according to claim 3 is characterized in that: In the step (1), an electromechanical coupling equivalent circuit is constructed according to the size and material parameters of the while drilling transducer. WITH 11 =Z 12 =Z 31 =Z 32 =jAZ0tan(βT1 / 2) (1) <h2 style=";text-align:left;direction:ltr">Z<h2 style=";text-align:left;direction:ltr"> 21 <h2 style=";text-align:left;direction:ltr"> =Z<h2 style=";text-align:left;direction:ltr"> 22 <h2 style=";text-align:left;direction:ltr"> = jρ CS tan(KT2 / 2) (3) In the formula, D = (Z 13 + Z 11 )(Z 23 + Z 31 )(Z 33 + Z 32 )(Z 11 Z 12 + Z 11 Z 13 + Z 11 Z 21 + Z 12 Z 13 + Z 13 Z 21 ), E=((Z 13 +Z 12 +Z 21 +Z 23 )WITH 33 +(With 22 +Z 23 +Z 31 )(WITH 12 +Z 13 +Z 21 ))WITH 32 +Z 33 (WITH 22 +Z 23 +Z 31 )(WITH 12 +Z 13 +Z 21 ), F=((Z 12 +Z 21 +Z 23 )WITH 33 +(With 22 +Z 23 +Z 31 )(WITH 12 +Z 21 ))WITH 32 +Z 33 (WITH 22 +Z 23 +Z 31 )(WITH 12 +Z 21 )。 Among them: Z11, Z12, Z13 represent the equivalent impedance of the ceramic sheet-1 inside the while drilling transducer, Z22, Z21, Z23 represent the equivalent impedance of the external packaging material of the while drilling transducer, Z31, Z32, Z33 represent the equivalent impedance of the ceramic sheet-2 inside the while drilling transducer, each part in the equivalent circuit model is a T-type circuit structure, the Z13 and Z33 impedances of the two piezoelectric ceramics are connected in series with the equivalent transformer, LP, LS, CP0, CP1 are the parameters of the Π-type dual-frequency impedance matching network components to be calculated, C0 is the static capacitance of the transducer, for the convenience of calculation, the impedance matching network is located on both sides of the piezoelectric ceramic sheet, T1 is the surface area of ​​the piezoelectric ceramic, T2 is the thickness of the piezoelectric ceramic, S is the surface area of ​​the packaging material, K is the wave number, j is a complex number, C is the material sound velocity, p is the piezoelectric material density, and p2 is the packaging material density.

5. The design method of the dual-band impedance matching circuit system of the while drilling acoustic wave transducer with residual vibration attenuation characteristics according to claim 3 is characterized in that: In the step (2): firstly, a target frequency band is set, and then a dynamic weight coefficient is set according to matching requirements to automatically track the average impedance within the frequency band of the circuit model, and when local optimal convergence is met, the parameters of the Π-type impedance matching network components are output.

6. The design method of the dual-band impedance matching circuit system of the while drilling acoustic wave transducer with residual vibration attenuation characteristics according to claim 3 is characterized in that: In the step (3): the inductor LS in the Π-type dual-frequency impedance matching network is connected in series with the secondary of the pulse boost transformer, the D pole of the MOS tube is connected to the upper end of the capacitor CPO in the dual-frequency impedance matching network and then connected in series with the matching inductor LP, the matching inductor LP is connected to the upper end of the matching capacitor CP1 and then connected in series with the matching inductor LS, the S pole is connected to the excitation circuit GND, the G pole is connected to the main control pulse of the excitation control circuit, the high-voltage output end of the excitation circuit is connected in parallel with the matching network capacitor, the positive and negative electrodes of the drilling transducer are connected to the secondary of the pulse transformer, and assembled into a module system.

7. The design method of a dual-band impedance matching circuit system of a while-drilling acoustic wave transducer with residual vibration attenuation characteristics according to claim 6 is characterized in that: When the excitation signal ends, the excitation circuit pulls the G pole of the MOS tube up to 15V and maintains it for 5-10ms before pulling it down to a low level.

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