A method and system for measuring performance indicators of acoustic logging transducers

Abstract

This invention discloses a method and system for measuring the performance indicators of an acoustic logging transducer, belonging to the field of geophysical logging technology. The method derives an admittance circle measurement method using an equivalent lumped system of the transducer; an admittance circle measurement system is constructed based on this method; the electrical parameters of the transducer are measured using this system to obtain the transducer admittance curve and admittance circle diagram; and the transducer's performance indicators are calculated based on these diagrams. This invention provides more accurate measurement results and simplifies the operation of testing the admittance circle and performance indicators of the transducer.

Description

Technical Field

[0001] This invention belongs to the field of geophysical logging technology and relates to a method and system for measuring the performance indicators of acoustic logging transducers. Background Technology

[0002] Sonic logging is a well logging method that utilizes the differences in acoustic properties, such as velocity, amplitude, and frequency, as sound waves propagate through different rocks to study wellbore geological profiles, assess cementing quality, and detect casing damage. The acoustic transducer is the core component of an acoustic logging tool. Excited by a pulse signal, it emits sound waves into the formation. By measuring parameters such as the velocity, time difference, and amplitude of the acoustic waves in the formation, it calculates rock porosity, identifies lithology, and determines gas-bearing layers.

[0003] Piezoelectric ceramic transducers are commonly used in acoustic logging. These transducers can function as both transmitting and receiving transducers. The manufacturing process of piezoelectric transducer materials involves the following steps: batching → mixing → pre-firing → crushing → molding → binder removal → sintering → back silvering → polarization. Each of these steps significantly impacts the performance of the piezoelectric ceramic; even piezoelectric ceramics produced from the same batch of materials and using the same process can exhibit substantial differences in performance. Therefore, testing the piezoelectric ceramic is a prerequisite for the successful application of piezoelectric ceramic transducers.

[0004] In the development process, to obtain transducers with superior performance indicators, it is necessary to test the transducer's performance parameters, such as resonant frequency, bandwidth, dynamic resistance, dynamic capacitance, and electromechanical coupling coefficient. However, the performance parameters obtained by existing testing methods are not precise enough, making it difficult to obtain accurate performance parameters from the analysis of test results. Therefore, there is an urgent need to develop a new method for measuring the performance parameters of acoustic logging transducers to accurately measure these parameters. These parameters can then be used to guide the development and production of transducers, maximizing the reliability and stability of the developed products. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for measuring the performance indicators of acoustic logging transducers, so as to solve the technical problem that the measurement results of the performance indicators of acoustic logging transducers are not accurate enough in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for measuring the performance indicators of an acoustic logging transducer, comprising the following steps:

[0008] A method for measuring the admittance circle is obtained by using the equivalent lumped system of the transducer;

[0009] Based on the admittance circle measurement method, construct an admittance circle measurement system;

[0010] The electrical parameters of the transducer are measured using the admittance circle measurement system to obtain the transducer admittance curve and admittance circle diagram.

[0011] Based on the transducer admittance curve and admittance circle diagram, the performance indicators of the transducer are calculated.

[0012] Furthermore, the step of obtaining the admittance circle measurement method through the equivalent lumped system of the transducer specifically includes:

[0013] In the equivalent circuit of the transducer's equivalent lumped system, the total admittance Y = parallel branch Y0 + series branch Y1; with conductance as the abscissa and susceptance as the ordinate, when the frequency changes within the range near the resonant frequency, the trajectory of the phase vector terminal of Y1 is a circle with its center at (1 / 2R1, 0) and radius at (1 / 2R1); when the phase vector terminal of Y1 rotates one revolution, the phase vector terminal of Y0 is approximately considered to be a constant with frequency. Therefore, by translating the trajectory circle of Y1 upwards along the longitudinal axis in the complex plane, we obtain the admittance circle:

[0014] Y0=jωC0

[0015] Y1=G1+jB1

[0016]

[0017] In the formula, j is the imaginary number; ω is the angular frequency; C0 is the pure capacitance in the equivalent circuit; G1 is the conductance in the equivalent circuit; B1 is the susceptance in the equivalent circuit; R1 is the equivalent resistance; L1 is the equivalent inductance; and C1 is the equivalent capacitance.

[0018] The equation of a circle is obtained by completing the square:

[0019]

[0020] Compared to G and B, since ωC0 changes very little with frequency, the admittance of the transducer changes in frequency in a circle. The admittance circle can comprehensively reflect the electrical parameters of the transducer, and the electrical parameters of the transducer can be obtained by measuring the admittance circle.

[0021] Furthermore, the equivalent circuit of the transducer equivalent lumped system includes a pure capacitor C0 and an equivalent resistor R1, an equivalent inductor L1, and an equivalent capacitor C1 connected in parallel with the pure capacitor C0; the equivalent resistor R1, the equivalent inductor L1, and the equivalent capacitor C1 are connected in series.

[0022] Furthermore, the step of measuring the electrical parameters of the transducer using the admittance circle measurement system and plotting the admittance circle diagram specifically includes:

[0023] Keeping the voltage V constant in the admittance circle measurement system, the frequency is changed to obtain the transducer admittance curve and plot the admittance circle diagram.

[0024] Furthermore, the performance indicators include the mechanical resonant frequency f of the transducer. s Equivalent bandwidth Δf, mechanical quality factor Q m and electromechanical coupling coefficient k eff The specific calculation formula is as follows:

[0025]

[0026] Δf=F2-F1

[0027]

[0028] In the formula, L1 is the equivalent inductance; C1 is the equivalent capacitance; F2 and F1 are the frequencies of the transducer at the half-power point; F s F is the resonant frequency; a It is the anti-resonant frequency.

[0029] Furthermore, it also includes: determining whether the performance indicators of the transducers are consistent through correlation function analysis, and completing the screening analysis; the error between the transducer performance indicators and the theoretical design value must be less than or equal to 10%, and the performance indicator error between transducers in the same batch must be less than or equal to 5%.

[0030] Secondly, this invention provides a system for measuring the performance indicators of an acoustic logging transducer, including an input transformer B1, an output transformer B2, and a standard admittance Y. x The admittance Y of the transducer under test t The input transformer B1 is connected to the signal generator via a measuring switch K; the primary winding of the input transformer B1 is connected to the signal generator, and the secondary winding of the input transformer B1 is connected to the admittance Y of the transducer under test. t One end and standard admittance Y x One end; the admittance Y of the transducer under test t The other end is connected to the second primary winding n2 of the output transformer B2; standard admittance Y x One end is also connected to the switch K, and the standard admittance Y x The other end is connected to the first primary winding n1 of the output transformer B2; the secondary winding of the output transformer B2 is connected to the computer.

[0031] Furthermore, the output transformer B2 is a differential transformer.

[0032] Furthermore, the first primary winding n1 of the output transformer B2 is equal to the second primary winding n2.

[0033] Furthermore, the magnetic core of the output transformer B2 is ferrite.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention discloses a method and system for measuring the performance indicators of an acoustic logging transducer. Based on the equivalent lumped system of the transducer, a method for measuring the admittance circle is derived. An admittance circle measurement system is constructed based on this method. In this system, the standard admittance is adjusted so that the admittance of the transducer under test equals the standard admittance. At this point, the resultant magnetic flux of the output transformer is zero, and the admittance bridge is balanced. Therefore, the admittance of the transducer under test can be directly measured from the standard. This yields the transducer admittance curve and admittance circle diagram, and finally, the transducer's performance indicators are calculated. The measurement method of this invention provides more accurate results and is simple to operate. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of the method of the present invention;

[0038] Figure 2 This is an equivalent circuit diagram of the transducer in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the admittance circle in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the admittance circle measurement system according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the admittance circle measurement method according to an embodiment of the present invention;

[0042] Figure 6 This is a diagram showing the measurement results of the admittance circle of the acoustic logging transducer in an embodiment of the present invention.

[0043] Where: C0 - pure capacitor; R1 - equivalent resistance; L1 - equivalent inductance; C1 - equivalent capacitance; B1 - input transformer; B2 - output transformer; Y x -Standard admittance; Y t - Admittance of the transducer under test; K - Measurement switch; n1 - First primary winding; n2 - Second primary winding. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present 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, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0048] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0049] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0050] The present invention will now be described in further detail with reference to the accompanying drawings:

[0051] See Figure 1 This invention discloses a method for measuring the performance indicators of an acoustic logging transducer, comprising the following steps:

[0052] S1, the admittance circle measurement method is obtained through the equivalent lumped system of the transducer;

[0053] For piezoelectric devices, if there are no other resonants at frequencies far from a certain resonant frequency, then the piezoelectric device can be approximated as a lumped system near that resonant frequency, and its symbol and equivalent circuit are as follows: Figure 2 As shown.

[0054] In the absence of excitation vibration and neglecting electrical losses, the static equivalent circuit of a piezoelectric transducer is a pure capacitor, commonly denoted by C0. When the transducer vibrates and radiates energy, a dynamic impedance will exist. Here, R1, L1, and C1 represent the equivalent resistance, equivalent inductance, and equivalent capacitance of the transducer's no-load equivalent circuit, respectively.

[0055] In the equivalent circuit, assuming the total admittance of the piezoelectric device is Y, and the parallel and series branches (or static and dynamic admittances) are Y0 and Y1 respectively, then Y = Y0 + Y1. The dynamic admittance Y1 and the total admittance Y can be calculated as a function of frequency. Let the horizontal axis represent conductance (the real part of admittance) and the vertical axis represent susceptance (the imaginary part of admittance). When the frequency changes within the range near the resonant frequency, the trajectory of the phase vector terminal of Y1 is a circle with its center (1 / 2R1, 0) and radius 1 / 2R1. When the phase vector terminal of Y1 rotates one revolution, the change in the phase vector terminal of Y0 with frequency is generally small, approximately considered a constant. Therefore, the trajectory circle of Y1 is translated upwards along the vertical axis in the complex plane. This yields the trajectory circle of the phase vector terminal of the total admittance as a function of frequency, i.e., the admittance circle.

[0056] Y0=jωC0

[0057] Y1=G1+jB1

[0058]

[0059] The equation of a circle is obtained by completing the square:

[0060]

[0061] Compared to G and B, since ωC0 changes very little with frequency, the admittance of the transducer changes in frequency in a circular pattern, as shown below. Figure 3 As shown, the admittance circle comprehensively reflects the characteristic parameters of the transducer, and the performance parameters of the transducer can be obtained by measuring the admittance circle.

[0062] S2. Construct an admittance circle measurement system based on the admittance circle measurement method;

[0063] See Figure 4 The admittance circle measurement system includes an input transformer B1, an output transformer B2, and a standard admittance Y. x The admittance Y of the transducer under test t The input transformer B1 is connected to the signal generator via a measuring switch K; the primary winding of the input transformer B1 is connected to the signal generator, and the secondary winding of the input transformer B1 is connected to the admittance Y of the transducer under test. t One end and standard admittance Y x One end; the admittance Y of the transducer under test t The other end is connected to the second primary winding n2 of the output transformer B2; standard admittance Y x One end is also connected to the switch K, and the standard admittance Y x The other end is connected to the first primary winding n1 of the output transformer B2; the secondary winding of the output transformer B2 is connected to the computer.

[0064] Figure 4 The portion within the dashed box is the bridge section of the admittance bridge. B1 is the input transformer, and B2 is the output transformer. It is a 1:1 (i.e., n1 = n2) differential transformer with a ferrite core. x Standard admittance is typically composed of standard conductance and standard capacitance connected in parallel, Y t is the admittance of the transducer under test. k is the balanced or unbalanced measurement switch, n1 and n2 are two identical parts of the primary winding of the output transformer, and the parts outside the bridge body are the same as those used in the impedance bridge.

[0065] S3, the electrical parameters of the transducer are measured by the admittance circle measurement system to obtain the transducer admittance curve and admittance circle diagram;

[0066] After the signal is sent to the primary windings n1 and n2 of the output transformer B2 through the input transformer, it is applied to Y with the same amplitude and phase voltage. x and Y t On both arms, i is generated respectively. x i t Since n1 = n2, therefore i x i t The magnetic fields generated in the secondary winding of B2 are opposite. If Y is adjusted... x , so that exactly Y x =Y t Then there will be i x =i t Therefore, the resultant magnetic flux in B2 is equal to zero, and the admittance bridge is balanced. Thus, the admittance of the transducer under test can be directly obtained from the standard Y. x Measured. Keeping the voltage V = c constant, changing the frequency allows for the measurement of Y. t ~f and Bt ~f curve.

[0067] S4. Based on the transducer admittance curve and admittance circle diagram, the performance indicators of the transducer are calculated.

[0068] By measuring Y t From ~f, we can find the mechanical resonant frequency f of the transducer. s Equivalent bandwidth Δf, mechanical quality factor Q m and electromechanical coupling coefficient k eff The specific calculation formula is as follows:

[0069]

[0070] Δf=F2-F1

[0071]

[0072] S5 uses the performance indicators and admittance circle diagram obtained in S4 to evaluate and analyze the transducer.

[0073] In this step, the electrical performance parameters (G) of the transducer are measured using the admittance circle measurement method. max ,C0,C1,L1,R1 f s Q m K eff The analysis examines whether the operating frequency of the transducers meets the design requirements. For dipole acoustic wave transmitting transducers or array acoustic wave receiving transducers, their parameters must be completely consistent. When measuring the performance indicators of a group of transducers, according to industry standards, the error between the measured parameter values ​​and the theoretical design values ​​should be less than or equal to 10%, and the parameter error between transducers in the same group and batch should be less than or equal to 5%. The performance parameters of each group of transducers are measured using admittance circles, and the consistency of electrical and mechanical parameters between transducers is determined using correlation function analysis, thus completing the screening analysis.

[0074] In one feasible embodiment of the present invention, see [link to relevant documentation]. Figure 5 The admittance circle and performance indicators of the transducer were tested using the method and system of this invention. The results of the admittance circle measurement are as follows: Figure 6 As shown.

[0075] Figure 6 In the middle, from top to bottom, are the transducer admittance circle diagram, the transducer admittance curve (GB curve), and the measurement results of the transducer's electrical parameters.

[0076] Among them G max Admittance of a piezoelectric transducer at its resonant frequency.

[0077] f SThe resonant frequency is the frequency at which the real part of the admittance of the piezoelectric transducer is at its maximum, and it is the operating frequency of the vibration system.

[0078] f P Anti-resonance frequency: the resonant frequency of the parallel branch in the equivalent circuit of the piezoelectric transducer. At this frequency, the transducer impedance has its maximum value.

[0079] f1 / f2: The frequency of the transducer at the half-power point.

[0080] Δf: Half-power difference, defined as the bandwidth of the transducer's operating circuit.

[0081] Q m The ratio of the mechanical energy stored in a piezoelectric transducer at resonance to the mechanical energy lost in one cycle reflects the amount of energy consumed due to internal damping during vibration.

[0082] k eff Electromechanical coupling coefficient: A parameter in a piezoelectric transducer that represents the interconversion of mechanical and electrical energy. It is the ratio of the interaction energy density of the elastic medium to the geometric mean of the elastic energy density and the dielectric energy density, and is a parameter characterizing the conversion efficiency.

[0083] C0: Static capacitance: The capacitance of a piezoelectric transducer when the stress is zero (or in a free state).

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring the performance indicators of an acoustic logging transducer, characterized in that, Includes the following steps: A method for measuring the admittance circle is obtained by using the equivalent lumped system of the transducer; Based on the admittance circle measurement method, construct an admittance circle measurement system; The electrical parameters of the transducer are measured using the admittance circle measurement system to obtain the transducer admittance curve and admittance circle diagram. Based on the transducer admittance curve and admittance circle diagram, the performance indicators of the transducer are calculated.

2. The method for measuring the performance indicators of an acoustic logging transducer according to claim 1, characterized in that, The steps of obtaining the admittance circle measurement method through the equivalent lumped system of the transducer specifically include: In the equivalent circuit of the transducer's equivalent lumped system, the total admittance Y = parallel branch Y0 + series branch Y1; with conductance as the abscissa and susceptance as the ordinate, when the frequency changes within the range near the resonant frequency, the trajectory of the phase vector terminal of Y1 is a circle with its center at (1 / 2R1, 0) and radius at (1 / 2R1); when the phase vector terminal of Y1 rotates one revolution, the phase vector terminal of Y0 is approximately considered to be a constant with frequency. Therefore, by translating the trajectory circle of Y1 upwards along the longitudinal axis in the complex plane, we obtain the admittance circle: Y0=jωC0 Y1=G1+jB1 In the formula, j is the imaginary number; ω is the angular frequency; C0 is the pure capacitance in the equivalent circuit; G1 is the conductance in the equivalent circuit; B1 is the susceptance in the equivalent circuit; R1 is the equivalent resistance; L1 is the equivalent inductance; and C1 is the equivalent capacitance. The equation of a circle is obtained by completing the square: Compared to G and B, since ωC0 changes very little with frequency, the admittance of the transducer changes in frequency in a circle. The admittance circle can comprehensively reflect the electrical parameters of the transducer, and the electrical parameters of the transducer can be obtained by measuring the admittance circle.

3. The method for measuring the performance indicators of an acoustic logging transducer according to claim 2, characterized in that, The equivalent circuit of the transducer equivalent lumped system includes a pure capacitor C0 and an equivalent resistor R1, an equivalent inductor L1, and an equivalent capacitor C1 connected in parallel with the pure capacitor C0; the equivalent resistor R1, the equivalent inductor L1, and the equivalent capacitor C1 are connected in series.

4. The method for measuring the performance indicators of an acoustic logging transducer according to claim 1, characterized in that, The step of measuring the electrical parameters of the transducer using the admittance circle measurement system and plotting the admittance circle diagram specifically includes: Keeping the voltage V constant in the admittance circle measurement system, the frequency is changed to obtain the transducer admittance curve and plot the admittance circle diagram.

5. The method for measuring the performance indicators of an acoustic logging transducer according to claim 1, characterized in that, The performance indicators include the mechanical resonant frequency f of the transducer. s Equivalent bandwidth Δf, mechanical quality factor Q m and electromechanical coupling coefficient k eff The specific calculation formula is as follows: Δf=F2-F1 In the formula, L1 is the equivalent inductance; C1 is the equivalent capacitance; F2 and F1 are the frequencies of the transducer at the half-power point; F s F is the resonant frequency; a It is the anti-resonant frequency.

6. The method for measuring the performance indicators of an acoustic logging transducer according to claim 1, characterized in that, Also includes: By using the correlation function analysis method, we can determine whether the performance indicators of the transducers are consistent and complete the screening analysis. The error between the transducer performance indicators and the theoretical design values ​​should be less than or equal to 10%, and the error between the performance indicators of transducers in the same batch should be less than or equal to 5%.

7. A system for measuring the performance indicators of an acoustic logging transducer, characterized in that, Includes input transformer B1, output transformer B2, and standard admittance Y. x The admittance Y of the transducer under test t The input transformer B1 is connected to the signal generator via a measuring switch K; the primary winding of the input transformer B1 is connected to the signal generator, and the secondary winding of the input transformer B1 is connected to the admittance Y of the transducer under test. t One end and standard admittance Y x One end; the admittance Y of the transducer under test t The other end is connected to the second primary winding n2 of the output transformer B2; standard admittance Y x One end is also connected to the switch K, and the standard admittance Y x The other end is connected to the first primary winding n1 of the output transformer B2; the secondary winding of the output transformer B2 is connected to the computer.

8. The acoustic logging transducer performance index measurement system according to claim 7, characterized in that, The output transformer B2 is a differential transformer.

9. A system for measuring the performance indicators of an acoustic logging transducer according to claim 7, characterized in that, The first primary winding n1 of the output transformer B2 is equal to the second primary winding n2.

10. A system for measuring the performance indicators of an acoustic logging transducer according to claim 7, characterized in that, The core of the output transformer B2 is made of ferrite.

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