A method and detector for receiving broadband signals in seismic exploration based on circuit balance

Abstract

This invention relates to the field of seismic exploration technology. Specifically, it relates to a broadband signal receiving method and detector for seismic exploration based on circuit balance. This invention utilizes a novel land-based detector capable of receiving broadband seismic signals. Its equivalent circuit design eliminates the need for series-connected equivalent filter capacitors or inductors and impedance matching, allowing direct connection to existing external node acquisition stations for seismic data acquisition. Field experiments in the Loess Plateau have yielded a broadband response within the 0–420 Hz range. Analysis of the Ricker wavelet from the field data shows superior sidelobe suppression compared to existing detectors. Furthermore, field consistency tests demonstrate good consistency for this type of detector. This design solves the problems of signal inconsistency, signal distortion, and impedance matching in existing piezoelectric detectors. Its most significant contribution is breaking through the current broadband technology bottleneck, representing the only equipment technology path currently available for broadband seismic exploration.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration technology, and more specifically, to a method and detector for receiving broadband seismic signals based on circuit balance. Background Technology

[0002] Seismic exploration is a core technology for deep oil and gas resource exploration and analysis of underground geological structures. Broadband seismic exploration is the direction of development for petroleum exploration and the source of improving seismic exploration resolution. It is crucial in deep and ultra-deep seismic exploration, microstructure exploration, and lithological exploration, and directly determines the ability to discover oil and gas.

[0003] Broadband seismic exploration mainly consists of two parts: excitation and reception. For land exploration, the existing excitation methods are primarily explosives and controlled seismic sources. Explosives are considered a full-frequency excitation source, while controlled seismic sources, with excitation frequencies ranging from 1.5 Hz to 160 Hz, also meet current seismic exploration requirements. Excitation energy varies by region, but overall, they all meet the needs. However, the receiving end has consistently failed to achieve broadband reception due to the low dominant frequency. Well logging and older data indicate that the receiver's bandwidth is limited by the geophone; it can only receive either high-frequency or low-frequency signals, not both simultaneously. Therefore, broadband seismic exploration has been impossible, resulting in an inability to simultaneously balance the stratigraphic analysis capabilities of high-frequency signals with the deep penetration capabilities of low-frequency signals. This leads to the contradiction of "clearly seeing stratigraphic details but not being able to detect deeper layers, or being able to detect deeper layers but not being able to see stratigraphic details," significantly reducing deep-layer exploration capabilities and reservoir prediction accuracy.

[0004] Secondly, existing detectors operate in narrow frequency bands. Although the test results are quite good, they cannot achieve wideband reception. Moreover, the filtering problem in their equivalent circuits cannot be solved within the existing theoretical framework. Therefore, wideband, low-distortion signal seismic exploration cannot be achieved, which directly affects the subsequent processing and interpretation of seismic data. Therefore, a wideband signal reception method and detector for seismic exploration based on circuit balance is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method and detector for receiving broadband signals in seismic exploration based on circuit balance, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, a broadband signal receiving method for seismic exploration based on circuit balance is provided. In the seismic exploration, seismic waves are excited by a broadband signal excitation point, and the seismic vibrations are received by a broadband land-based detector in a seismic wave receiving array and converted into broadband electrical signals. The broadband electrical signals are then transmitted to a seismic acquisition station for recording, forming broadband seismic data. Based on the receiving frequency characteristics of the work area, the receiving end frequency parameters are set or adjusted through circuit balance theory, so that the broadband land-based detector can perform low-distortion broadband reception within the set receiving frequency band. The broadband seismic data is processed, and the broadband seismic data corresponding to multiple broadband signal excitation points are superimposed to form a broadband profile to obtain seismic exploration results.

[0007] As a further improvement to this technical solution, the broadband signal excitation point is a controllable seismic source excitation point or a well shot excitation point deployed in the seismic exploration field. The seismic wave receiving array consists of broadband land-based geophones deployed at receiving points in the work area, and the observation system meets the coverage number of the target layer. The broadband land-based detector receives surface vibrations generated by broadband signal excitation points, converts the mechanical vibrations into broadband electrical signals, and then directly connects them to the seismic acquisition station for recording.

[0008] As a further improvement to this technical solution, during the processing of the broadband seismic data, data from different frequency bands are extracted according to the exploration objective; When it is necessary to probe deep or ultra-deep structures, low-frequency signal data is extracted to enhance deep penetration capability. When it is necessary to characterize reservoir details, thin-layer structure or microstructure, high-frequency signal data is extracted to improve formation resolution. The low-frequency signal data and high-frequency signal data are combined and processed to generate a broadband profile that balances deep penetration capability and shallow to mid-level resolution.

[0009] As a further improvement to this technical solution, the frequency parameters of the receiving end are determined through on-site experimental results in the construction area; The field experimental results include signal-to-noise ratio, phase consistency, wavelet consistency, low-frequency response, high-frequency response, and data recording volume at different receiving frequencies; Based on the field experiment results, the frequency parameters of the receiver were adjusted using circuit balance theory to reduce the amount of invalid data recording while ensuring wideband reception capability.

[0010] As a further improvement to this technical solution, the receiver frequency parameters include high-frequency balance parameters and low-frequency balance parameters; The high-frequency balance parameters are used to suppress attenuation, phase shift, and waveform distortion of high-frequency signals; The low-frequency balance parameters are used to suppress DC drift, low-frequency noise, and low-frequency impedance imbalance in low-frequency signals. When different geological conditions in the work area cause changes in the receiving frequency, the high-frequency balance parameters and low-frequency balance parameters are reset based on the results of field experiments.

[0011] As a further improvement to this technical solution, when determining the high-frequency balance parameters, the overlapping area between the seismic detection areas corresponding to multiple broadband signal excitation points is obtained and a calibration area list is generated. Select a near-layer calibration region from the calibration region list, extract high-frequency signal data from the near-layer calibration region, and identify the features of the near-layer region. Based on the near-layer region characteristics, the formation reflection interface of the near-layer calibration region is determined, and the standard stitched waveform corresponding to the formation reflection interface is extracted; The high-frequency signal data corresponding to the broadband signal excitation point is compared with the standard spliced ​​waveform. Based on the comparison results, the circuit adjustment range of the high-frequency link is deduced, and the high-frequency balance parameters are determined within the circuit adjustment range. When determining the low-frequency balance parameters, the high-frequency near-layer region characteristics after calibration with the high-frequency balance parameters are used as constraints to reverse-engineer the propagation law of the low-frequency signal in the strata and generate a standard low-frequency signal. Extract low-frequency signal data corresponding to the calibration area, and perform difference analysis between the low-frequency signal data and the standard low-frequency signal; Based on the difference analysis results, low-frequency link error is extracted, and low-frequency balance parameters are set according to the low-frequency link error. The low-frequency signal is then re-acquired using the set low-frequency balance parameters for verification.

[0012] As a further improvement to this technical solution, after obtaining the broadband profile, the broadband profile is calibrated to the true surface reference plane using surface survey data to form a true surface stratum broadband profile. Based on the experimental results of different work areas, the cutoff frequency band settings for low-frequency and high-frequency signals are determined so that the broadband land-based detector can perform low-distortion reception under full broadband reception conditions.

[0013] As a further improvement to this technical solution, when the receiving frequency of the work area changes due to the influence of the strata, after completing the current work area parameter setting, the process returns to the receiving end frequency parameter adjustment step to reset the parameters. Construction work in the entire work area will be carried out based on the final determined receiver frequency parameters, and the receiver frequency parameters will be dynamically adjusted according to changes in the receiver frequency during the process. The circuit balance theory refers to the fact that in the process of designing and adjusting the receiver circuit, the only evaluation criterion is not whether the traditional circuit forms a conventional loop. Instead, the receiver circuit status is evaluated and the receiver frequency parameters are set based on the balance between the energy conversion state of the piezoelectric components in the broadband land-based detector, the parasitic parameters of the signal output path, the input impedance of the seismic acquisition station, and the fidelity of the broadband signal.

[0014] The second objective of this invention is to disclose a detector, comprising a housing, a housing cover, a waterproof rubber ring, a tail cone, a mechanism clamping screw ring, a mechanism disposed within the housing, and an equivalent circuit corresponding to the mechanism. The tail cone is connected to the lower end of the outer shell and is used to insert into the ground and transmit ground vibrations to the outer shell; The outer cover is fitted onto the upper end of the outer shell, and the waterproof rubber ring is disposed between the outer shell and the outer cover to form a waterproof seal; The mechanism is pressed and fixed inside the outer casing by a mechanism clamping screw ring, and is used to convert the seismic vibration transmitted by the outer casing into a broadband electrical signal; The equivalent circuit is used to characterize the circuit relationship of the mechanism generating broadband electrical signals and outputting broadband electrical signals to the seismic acquisition station under seismic vibration. The mechanism includes a mechanism shell, an outer ring insulating ring, a spacer, an insulating washer, a top cover, and piezoelectric components; The outer ring insulating ring, spacer, insulating gasket, top cover, and piezoelectric components are disposed inside the mechanism housing; The piezoelectric components are clamped in the mounting space formed by the core housing and the top cover, and are electrically insulated from the core housing by an outer ring insulating ring, a spacer and an insulating washer. The piezoelectric element is used to generate a broadband electrical signal corresponding to the vibration acceleration under the seismic vibration transmitted by the tail cone and shell.

[0015] As a further improvement to this technical solution, the equivalent circuit includes a piezoelectric equivalent signal source, a piezoelectric equivalent capacitor, an insulating support equivalent impedance, a detector output terminal, and an input impedance of the seismic acquisition station. The piezoelectric equivalent signal source is used to equivalently represent the electrical signal generated by the piezoelectric element under seismic vibration. The piezoelectric equivalent capacitance is used to represent the capacitance characteristics of the piezoelectric component itself. The equivalent impedance of the insulating support is used to equivalently represent the insulating isolation relationship formed by the outer ring insulating ring, the spacer, and the insulating washer; The output of the detector is used to connect to the input of the seismic acquisition station. The input impedance of the seismic acquisition station is used to form a broadband signal acquisition relationship with the piezoelectric equivalent signal source, piezoelectric equivalent capacitance, and insulating support equivalent impedance after the detector is connected to the seismic acquisition station; The equivalent circuit satisfies the circuit balance relationship, which is the energy and signal balance suitable for broadband reception formed between the mechanical energy to electrical signal conversion of piezoelectric components, the energy storage and release of piezoelectric equivalent capacitors, the isolation effect of the insulating support equivalent impedance, the signal transmission at the detector output end, and the receiving effect of the input impedance of the seismic acquisition station. By balancing the circuit, the detector can output a low-distortion broadband electrical signal when connected to an existing seismic acquisition station.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this method and detector for receiving broadband signals in seismic exploration based on circuit balance, the detector, guided by the original fundamental theory of circuit balance, utilizes the piezoelectric effect of piezoelectric ceramics to reconstruct a new design concept and develop a broadband land-based detector. Its structure mainly consists of a core, an outer ring insulating ring, a spacer, an insulating gasket, a top cover, a shell, a tail cone, and a waterproof sealing structure, forming an integrated land-based broadband detector. The core part is the core, and the tail cone transmits ground vibrations to the detector, which then converts them into electrical signals. The generated electrical signals are directly output without filtering issues, and the output signals can be directly connected to existing node acquisition stations without impedance matching. Ultimately, a broadband response in the range of 0–420Hz is acquired in the field, exhibiting good multichannel consistency and high-fidelity seismic records.

[0017] 2. In this method and detector for receiving broadband signals in seismic exploration based on circuit balance, the calibrated high-frequency stratigraphic characteristics constrain the simulation of low-frequency signals, generating a standard low-frequency signal as a calibration benchmark. By correcting hardware errors such as DC drift, 1 / f noise, and low-frequency impedance mismatch in the circuit through low-frequency balance parameters, it is beneficial to receive low-frequency signals, thereby better utilizing the deep penetration capability of low-frequency signals and achieving a synergistic balance between high-frequency resolution and low-frequency penetration. This improves the problem of difficulty in achieving both "clear vision" and "deep vision" in broadband seismic exploration.

[0018] 3. In this method and detector for receiving broadband signals in seismic exploration based on circuit balance, high-frequency and low-frequency signals are simultaneously received on a single sensor through dual links. Combined with a parameter conflict tolerance mechanism and a global synchronous detection logic, it adapts to the hardware requirements of complex field exploration scenarios. It mainly optimizes the signal by adjusting the parameters of the hardware circuit, reducing the reliance on subsequent algorithm modifications, preserving the authenticity of the original seismic response of the strata to the greatest extent, and improving the system's operational stability and environmental adaptability. Ultimately, it achieves fine detection of ultra-deep geological structures and accurate identification of hidden oil and gas reservoirs, effectively improving the accuracy of deep seismic exploration and the success rate of resource exploration.

[0019] 4. In this method and detector for receiving broadband signals in seismic exploration based on circuit balance, a broadband profile is formed by superimposing the excited and received broadband signals. The inherent characteristics of the strata are identified based on the high signal-to-noise ratio signal in the near-layer calibration area. No additional dedicated calibration equipment is required, simplifying the field exploration process. At the same time, the range of circuit defects and the range of circuit adjustment of the high-frequency link are inferred based on the difference between the strata characteristics and the measured signal, realizing the location and orientation correction of circuit imbalance parameters. This reduces the attenuation and distortion of high-frequency signals from the hardware source, effectively improving the fidelity of high-frequency signals and the ability to characterize strata details, and ensuring the identification accuracy of shallow thin reservoirs and small structures. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the equivalent circuit of the detector of the present invention; Figure 2 This is a schematic diagram of the core structure of the detector of the present invention; Figure 3 This is a schematic diagram of the overall structure of the detector of the present invention; Figure 4 This is a comparative schematic diagram of (a) the novel land-based high-precision broadband detector LHBG-01 and (b) the integrated machine (node ​​instrument) of the present invention; Figure 5 This is a comparative schematic diagram of the LHBG-01 (left 14 channels) high-precision broadband geophone for land use and the high-sensitivity geophone (right 14 channels) for well shots. Figure 6 This is a schematic diagram showing the well-shot scanning frequency of 5~10Hz in this invention; Figure 7 This is a schematic diagram showing the well-shot scanning frequency of the present invention, which is 5~140Hz. Figure 8 This is a schematic diagram showing the well-shot scanning frequency of the present invention, which is 20~40Hz. Figure 9 This is a schematic diagram showing the well-shot scanning frequency of the present invention, which is 60~120Hz. Figure 10 The images show the spectrum scans at different depths of the present invention (left: novel piezoelectric detector; right: high-sensitivity detector). Figure 11 The diagram shows the wavelet consistency analysis of (a) a high-sensitivity detector excited by a seismic source (5-7-9-11 channels) and (b) a new type of land-based high-precision broadband detector LHBG-01 excited by a seismic source (5-7-9-11 channels). Figure 12 This is a schematic diagram of the amplitude-frequency curve of the novel piezoelectric detector of the present invention; Figure 13 This is a schematic diagram of the phase frequency curve of the novel piezoelectric detector of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described herein are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] Example 1: The purpose of this example is to provide a broadband signal receiving method for seismic exploration based on circuit balance. In seismic exploration, seismic waves are excited by a broadband signal excitation point. The seismic vibrations are received by a broadband land-based detector in the seismic wave receiving array and converted into broadband electrical signals. The broadband electrical signals are then transmitted to the seismic acquisition station for recording, forming broadband seismic data. Based on the receiving frequency characteristics of the work area, the frequency parameters of the receiving end are set or adjusted through circuit balance theory, so that the broadband land-based detector can perform low-distortion broadband reception within the set receiving frequency band. Broadband seismic data is processed, and broadband seismic data corresponding to multiple broadband signal excitation points are superimposed to form a broadband profile to obtain seismic exploration results. The broadband signal excitation point is the controllable source excitation point or well shot excitation point deployed in the seismic exploration field; The seismic wave receiving array consists of broadband land-based geophones deployed at receiving points in the work area, and the observation system meets the coverage number of the target layer. Broadband land-based detectors receive surface vibrations generated by broadband signal excitation points, convert the mechanical vibrations into broadband electrical signals, and then directly connect them to seismic acquisition stations for recording.

[0023] Complete the layout of the seismic exploration field work area, determine the broadband signal excitation point, and select the controllable source excitation point or the well shot excitation point; According to the observation system design plan, broadband land-based geophones are evenly deployed at the receiving points in the work area to form a seismic wave receiving array, ensuring that the observation system meets the target layer coverage requirements. The broadband land-based geophones are deployed close to the ground surface to directly receive the ground vibration signals generated by the broadband signal excitation points, accurately converting the mechanical vibrations into broadband electrical signals. There are no intermediate transfer links, and the signals are directly connected to the seismic acquisition station to complete the real-time recording of raw data. During the processing of broadband seismic data, data from different frequency bands are extracted according to the exploration objectives; When it is necessary to probe deep or ultra-deep structures, low-frequency signal data is extracted to enhance deep penetration capability. When it is necessary to characterize reservoir details, thin-layer structure or microstructure, high-frequency signal data is extracted to improve formation resolution. By combining low-frequency and high-frequency signal data, a broadband profile is generated that balances deep penetration capability with shallow and mid-level resolution.

[0024] The raw broadband seismic data recorded by the seismic acquisition station is processed by frequency band and the corresponding frequency band data is extracted flexibly according to the exploration target. When probing deep and ultra-deep geological structures, low-frequency signal data is extracted, and the characteristics of low-frequency signals, such as low attenuation and strong penetration, are used to ensure the depth of exploration. When characterizing reservoir details, thin-layer structures, or microstructures, high-frequency signal data is extracted, and the high resolution of high-frequency signals is used to improve the accuracy of formation characterization. Low-frequency signal data and high-frequency signal data are processed together and fused to generate a broadband profile that takes into account both deep penetration capability and shallow and middle layer resolution.

[0025] The receiver frequency parameters were determined based on the results of on-site experiments in the construction area. The field experimental results include signal-to-noise ratio, phase consistency, wavelet consistency, low-frequency response, high-frequency response, and data recording volume at different receiving frequencies; Based on the results of the field experiment, the frequency parameters of the receiver were adjusted using circuit balance theory to reduce the amount of invalid data recording while ensuring wideband reception capability.

[0026] In-situ field experiments were conducted at the construction site to test six core indicators at different receiving frequencies: signal-to-noise ratio, phase consistency, wavelet consistency, low-frequency response, high-frequency response, and data recording volume. Based solely on the results of the field experiments, the frequency parameters of the receiving end were adjusted in conjunction with circuit balance theory. While ensuring the full-bandwidth receiving capability of the broadband land-based detector, invalid signals were eliminated, redundant data recording volume was reduced, and data acquisition efficiency and quality were improved.

[0027] The receiver frequency parameters include high-frequency balance parameters and low-frequency balance parameters; High-frequency balance parameters are used to suppress attenuation, phase shift, and waveform distortion of high-frequency signals; Low-frequency balance parameters are used to suppress DC drift, low-frequency noise, and low-frequency impedance imbalance in low-frequency signals. When different geological conditions in the work area cause changes in the receiving frequency, the high-frequency balance parameters and low-frequency balance parameters are reset based on the results of field experiments.

[0028] The receiver frequency parameters are divided into two categories: high-frequency balanced parameters and low-frequency balanced parameters, so as to achieve signal optimization in different frequency bands. High-frequency balance parameters are used to suppress high-frequency signal transmission attenuation, phase shift, and waveform distortion, ensuring the fidelity of high-frequency signals. Low-frequency balance parameters are used to suppress DC drift, low-frequency noise, and low-frequency impedance imbalance in low-frequency signals, thereby ensuring the stability of low-frequency signals. When changes in the strata conditions within the work area cause a shift in the receiving frequency, the field experiment is repeated to reset the high-frequency and low-frequency balance parameters.

[0029] When determining the high-frequency balance parameters, the overlapping areas between the seismic detection areas corresponding to multiple broadband signal excitation points are obtained and a list of calibration areas is generated. Select the near-layer calibration region from the calibration region list, extract the high-frequency signal data of the near-layer calibration region, and identify the features of the near-layer region. Based on the characteristics of the near-layer region, the formation reflection interface of the near-layer calibration area is determined, and the standard stitched waveform corresponding to the formation reflection interface is extracted. The high-frequency signal data corresponding to the broadband signal excitation point is compared with the standard spliced ​​waveform. Based on the comparison results, the circuit adjustment range of the high-frequency link is deduced, and the high-frequency balance parameters are determined within the circuit adjustment range. To conduct precise calibration of high-frequency balance parameters, the overlapping areas of multiple broadband signal excitation points corresponding to seismic detection areas are first obtained, and a list of calibration areas is generated. Near-layer calibration areas are then selected from the list, and high-frequency signal data for these areas is extracted, along with identification of nearby geological features. Based on these features, the stratigraphic reflection interface is determined, and the corresponding standard spliced ​​waveform is extracted. The measured high-frequency signal data from the broadband signal excitation points is compared point-by-point with the standard spliced ​​waveform. Based on the differences, the adjustment range of the high-frequency link circuit is deduced, and the final high-frequency balance parameters are determined within this adjustment range, as shown in the following formula: ; in, This represents the difference in high-frequency signals (circuit loss quantification). To measure high-frequency signals, The standard spliced ​​waveform is represented by N, which is the number of signal sampling points.

[0030] When determining the low-frequency balance parameters, the high-frequency near-layer region characteristics after calibration with the high-frequency balance parameters are used as constraints to reverse-engineer the propagation law of the low-frequency signal in the strata and generate a standard low-frequency signal. Extract low-frequency signal data corresponding to the calibration area and perform difference analysis between the low-frequency signal data and the standard low-frequency signal; Based on the difference analysis results, low-frequency link error is extracted, and low-frequency balance parameters are set according to the low-frequency link error. The low-frequency signal is then re-acquired using the set low-frequency balance parameters for verification.

[0031] Accurate calibration of low-frequency balance parameters was conducted. Using the high-frequency near-layer regional characteristics after high-frequency balance parameter calibration as constraints, the propagation law of low-frequency signals in the strata was inversely deduced through a formation propagation model to generate a distortion-free standard low-frequency signal. Measured low-frequency signal data consistent with the spatial location of the calibration area were extracted, and a difference analysis was performed between the measured low-frequency signal and the standard low-frequency signal. Based on the difference results, the low-frequency link circuit error was extracted, and the low-frequency balance parameters were set according to the error magnitude. After parameter setting, low-frequency signals were re-acquired to complete the calibration verification. The formula is as follows: ; in, The signal is a distortion-free standard low-frequency signal, and F is the formation propagation operator. This is the high-frequency stratigraphic feature matrix after calibration.

[0032] After obtaining the broadband profile, the surface survey data is used to calibrate the broadband profile to the true surface reference plane to form a true surface strata broadband profile. Based on the experimental results of different work areas, the cutoff frequency band settings for low-frequency and high-frequency signals are determined so that the broadband land-based detector can perform low-distortion reception under full-bandwidth reception conditions.

[0033] After the broadband profile is generated, surface survey data of the work area is introduced to uniformly calibrate the broadband profile to the true surface reference plane, eliminating imaging errors caused by topographic undulations and surface low-velocity bands, and forming an accurate true surface stratum broadband profile. Combined with the field test results of different work areas, the cutoff frequency parameters of low-frequency and high-frequency signals are determined to ensure that the broadband land-based detector can achieve low-distortion signal acquisition under full broadband reception conditions.

[0034] When the receiving frequency of the work area changes due to the influence of the strata, after completing the current work area parameter settings, return to the receiving end frequency parameter adjustment step to reset the parameters. Construction work in the entire work area will be carried out based on the final determined receiver frequency parameters, and the receiver frequency parameters will be dynamically adjusted according to changes in the receiver frequency during the process. Circuit balance theory refers to the evaluation of the receiver circuit state and setting the receiver frequency parameters based on the balance between the energy conversion state of piezoelectric components in broadband land-based detectors, parasitic parameters of signal output paths, input impedance of seismic acquisition stations, and broadband signal fidelity during the design and parameter tuning of receiver circuits.

[0035] When changes in geological conditions cause a shift in the receiving frequency in the work area, after setting the parameters for the current block, return to the receiving frequency parameter adjustment step and conduct experiments and parameter calibration again; use the finally determined high-frequency and low-frequency balance parameters to carry out exploration and construction in the entire work area, monitor the changes in receiving frequency in real time during construction, and dynamically correct the receiving frequency parameters. The entire process follows the circuit balance theory, focusing on the balance between the energy conversion state of piezoelectric components, parasitic parameters of the signal output path, input impedance of the seismic acquisition station, and the fidelity of broadband signals. It evaluates the receiver circuit state and sets frequency parameters, without using traditional circuit loops as the sole evaluation criterion.

[0036] Example 2, as Figures 1 to 13 As shown, this embodiment provides a novel land-based high-precision broadband detector (LHBG-01), which is used to receive subsurface reflection signals in seismic exploration and serves as the sole broadband signal receiver in the aforementioned broadband seismic exploration receiving method based on circuit balance theory.

[0037] It includes the outer casing, the outer casing cover, the waterproof rubber ring, the tail cone, the movement clamping screw ring, the movement housed inside the outer casing, and the equivalent circuit corresponding to the movement. The tail cone is connected to the lower end of the outer shell and is used to insert into the ground and transmit ground vibrations to the outer shell; The outer cover fits onto the top of the outer shell, and a waterproof rubber ring is placed between the outer shell and the outer cover to form a waterproof seal; The movement is pressed and fixed inside the outer casing by a movement clamping screw ring, and is used to convert the seismic vibration transmitted by the outer casing into a broadband electrical signal; The equivalent circuit is used to characterize the circuit relationship of the mechanism generating broadband electrical signals and outputting broadband electrical signals to the seismic acquisition station under seismic vibration. The movement includes a movement housing, an outer ring insulating ring, spacers, insulating washers, a top cover, and piezoelectric components; The outer ring insulating ring, spacer, insulating gasket, top cover, and piezoelectric components are housed inside the mechanism housing; The piezoelectric components are clamped in the mounting space formed by the core housing and the top cover, and are electrically insulated from the core housing by an outer ring insulating ring, a spacer and an insulating washer; Piezoelectric components are used to generate broadband electrical signals corresponding to vibration acceleration under seismic vibration transmitted through the tail cone and shell; The equivalent circuit includes a piezoelectric equivalent signal source, a piezoelectric equivalent capacitance, an insulating support equivalent impedance, a detector output terminal, and an input impedance of the seismic acquisition station; The piezoelectric equivalent signal source is used to equivalently represent the electrical signal generated by piezoelectric components under seismic vibration. Piezoelectric equivalent capacitance is used to represent the capacitance characteristics of a piezoelectric component itself. The equivalent impedance of the insulation support is used to equivalently represent the insulation isolation relationship formed by the outer ring insulation ring, the spacer, and the insulation washer. The detector output is used to connect to the input of the seismic acquisition station; The input impedance of the seismic acquisition station is used to form a broadband signal acquisition relationship with the piezoelectric equivalent signal source, piezoelectric equivalent capacitance, and insulating support equivalent impedance after the detector is connected to the seismic acquisition station; The equivalent circuit satisfies the circuit balance relationship, which is the energy and signal balance suitable for broadband reception formed between the mechanical energy to electrical signal conversion of piezoelectric components, the energy storage and release of piezoelectric equivalent capacitance, the isolation effect of the insulating support equivalent impedance, the signal transmission at the detector output end, and the receiving effect of the input impedance of the seismic acquisition station. By balancing the circuit, the detector can output a low-distortion broadband electrical signal when connected to an existing seismic acquisition station. The land-based detector Figure 3 As shown, the detector includes a housing, a housing cover, a waterproof rubber ring, a tail cone, a mechanism clamping screw, and a mechanism. The tail cone is located at the lower end of the housing and is used to insert into the ground surface and transmit ground vibrations to the housing. The housing cover is fitted onto the upper end of the housing, and the waterproof rubber ring is located between the housing and the housing cover to prevent moisture and sediment from entering the housing from the field. The mechanism clamping screw is located inside the housing to clamp and fix the mechanism, ensuring the stability of vibration transmission between the mechanism and the housing.

[0038] The mechanism includes a mechanism housing, an outer ring insulating ring, spacers, insulating washers, a top cover, and piezoelectric components. The piezoelectric components are housed within the mechanism housing and held in place by the mounting space formed by the top cover and the mechanism housing. The outer ring insulating ring, spacers, and insulating washers provide insulation and positioning between the piezoelectric components and the mechanism housing, enabling the piezoelectric components to stably output electrical signals when subjected to seismic vibrations, while also reducing the impact of assembly errors on multichannel consistency.

[0039] Among them, it can stably output electrical signals when excited by seismic vibration, and at the same time reduce the impact of assembly errors on multi-channel consistency. When working, the tail cone is inserted into the ground surface. The ground vibration caused by seismic waves is transmitted through the tail cone and the outer shell to the core shell and piezoelectric components. The piezoelectric components generate electrical signals corresponding to the vibration acceleration based on the piezoelectric effect, forming the detector signal source.

[0040] In one specific implementation, the equivalent output of the detector can be represented as a signal source generated by a piezoelectric element directly connected to the input terminal of the acquisition node. No equivalent filter capacitor connected in series with the signal source is included in the output path, enabling the acquisition node to receive more complete broadband seismic signals (low-frequency signals are particularly advantageous). Field experimental data shows that it can receive weak reflected signals emitted from ultra-deep strata. This original circuit design, based on the original theoretical circuit balance theory, along with its circuit structure, manufacturing process, and construction mode, allows the detector to possess the response characteristics of an acceleration detector while also being directly adaptable to existing external nodes during field acquisition. Most importantly, it can acquire broadband signals in the field, and its compact size lays a solid foundation for the miniaturization and lightweighting of detectors.

[0041] After a series of experiments, an original circuit balance theory was proposed, and a new type of land-based high-precision broadband detector, LHBG-01, was developed based on this theory. Circuit balance theory is a circuit design approach that no longer evaluates the quality of a circuit design based on the traditional method of forming a loop, but rather on whether the energy or other components in the circuit are in balance.

[0042] Guided by in-depth research into circuit balance theory, a new detector was developed using the piezoelectric effect of piezoelectric ceramics as a signal source. This detector, also an acceleration detector, possesses the characteristics of an acceleration detector. The difference lies in the equivalent circuit of the new piezoelectric detector. Figure 1 The signal source U generated by the detector is in Figure 1 There is no equivalent series capacitance, thus solving the problems of bandwidth, signal inconsistency, and signal distortion.

[0043] During use, it can be directly connected to external nodes without impedance matching. Experiments with eSeis external nodes have been conducted in the field. In addition, the signal strength generated by the detector itself is sufficient, and signal amplification is not required.

[0044] A consistent tapping test was conducted in the field with the all-in-one PC, and the results were as follows: Figure 5 As shown, the experimental results are consistent with the data from the all-in-one machine, and the consistency effect of the 14 channels is good, thus solving the consistency problem.

[0045] Secondly, a comparative experiment was conducted between well shot and seismic source remote-source testing. The specific experimental results are as follows: Field well shot experimental data are as follows: Figure 5 As shown; Figure 6 The results of the 5~10Hz frequency division scanning show that the new land-based high-precision broadband detector LHBG-01 acquired the first arrival wave but it was discontinuous, and the high-sensitivity detector on the right side was also discontinuous. Figure 7With a frequency division scanning of 5~140Hz, the first arrival wave of the new piezoelectric detector is clearly visible; Figure 8 With a frequency division scanning range of 20~40Hz, the first arrival wave of the new piezoelectric detector can be distinguished; Figure 9 With a frequency division scanning of 60~120Hz, the initial arrival wave of the new piezoelectric detector is still clear, while the initial arrival wave of the high-sensitivity detector on the right is difficult to identify.

[0046] The frequency division scanning results above show that the new piezoelectric detector performs similarly to the high-sensitivity detector in the low-frequency range, while it has a significant advantage in the high-frequency range.

[0047] To verify the frequency response of the new land-based high-precision broadband detector LHBG-01 to targets at different depths, a spectrum analysis method was used to analyze data from different time windows. The initial arrival time was approximately 2.05s, and the total recording time was 8s.

[0048] Based on this, the shallow layer time window is set to 2~3s, the middle layer time window to 4.4~5.4s, and the deep layer time window to 6.4~7.4s.

[0049] Figure 10 a represents the shallow time window spectrum. The frequency range of the new piezoelectric detector is 0~420Hz at -25dB, while that of the high-sensitivity detector is 2~150Hz. Figure 10 b represents the mid-level time window spectrum, with the new piezoelectric detector ranging from 0 to 420 Hz and the high-sensitivity detector ranging from 2 to 150 Hz. Figure 10 c represents the deep time window spectrum, with the new piezoelectric detector ranging from 0 to 420 Hz and the high-sensitivity detector ranging from 2 to 150 Hz.

[0050] The shallow, medium and deep spectral analysis results show that the new land-based high-precision broadband geophone LHBG-01 effectively solves the problems of insufficient low frequency and limited high frequency of existing geophones, and meets the current needs of high-resolution seismic exploration. In the testing of the second sample, the SNT200 detector tester was used to test the core sample, and the sample sensitivity reached 31.7V / (m / s). In the field comparison experiment (first sample), the detector showed an effective frequency band of 0-420Hz in the shallow, middle and deep time windows, and maintained a relatively clear first arrival wave identification capability in the high-frequency range. The multi-channel impact test results showed good consistency, and the Ricker wavelet processing results showed good sidelobe suppression effect, indicating that the detector is beneficial to improving the fidelity of broadband seismic signal reception, as shown below: ; The test results confirm that the sensitivity of the new land-based high-precision broadband detector LHBG-01 can reach 31.7 (V / m / s), which meets current production requirements. There was one abnormal data point of 24.2 (V / m / s). The normal damping is 0.019, and this detector also showed an abnormal value of 0, indicating that the detector mechanism was damaged. The overall test results showed good consistency in the data of the mechanism.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and technical modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for receiving broadband signals in seismic exploration based on circuit balance, characterized in that: In the earthquake exploration, seismic waves are excited by a broadband signal excitation point. The seismic vibrations are received by broadband land-based geophones in the seismic wave receiving array and converted into broadband electrical signals. The broadband electrical signals are then transmitted to the seismic acquisition station for recording, forming broadband seismic data. Based on the receiving frequency characteristics of the work area, the receiving end frequency parameters are set or adjusted through circuit balance theory, so that the broadband land-based detector can perform low-distortion broadband reception within the set receiving frequency band. The broadband seismic data is processed, and the broadband seismic data corresponding to multiple broadband signal excitation points are superimposed to form a broadband profile to obtain seismic exploration results.

2. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 1, characterized in that: The broadband signal excitation point is a controllable seismic source excitation point or a well shot excitation point deployed in the seismic exploration field. The seismic wave receiving array consists of broadband land-based geophones deployed at receiving points in the work area, and the observation system meets the coverage number of the target layer. The broadband land-based detector receives surface vibrations generated by broadband signal excitation points, converts the mechanical vibrations into broadband electrical signals, and then directly connects them to the seismic acquisition station for recording.

3. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 1, characterized in that: During the processing of the broadband seismic data, data in different frequency bands are extracted according to the exploration objectives; When it is necessary to probe deep or ultra-deep structures, low-frequency signal data is extracted to enhance deep penetration capability. When it is necessary to characterize reservoir details, thin-layer structure or microstructure, high-frequency signal data is extracted to improve formation resolution. The low-frequency signal data and high-frequency signal data are combined and processed to generate a broadband profile that balances deep penetration capability and shallow to mid-level resolution.

4. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 1, characterized in that: The frequency parameters of the receiving end were determined based on the results of on-site experiments in the construction area. The field experimental results include signal-to-noise ratio, phase consistency, wavelet consistency, low-frequency response, high-frequency response, and data recording volume at different receiving frequencies; Based on the field experiment results, the frequency parameters of the receiver were adjusted using circuit balance theory to reduce the amount of invalid data recording while ensuring wideband reception capability.

5. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 4, characterized in that: The receiver frequency parameters include high-frequency balance parameters and low-frequency balance parameters; The high-frequency balance parameters are used to suppress attenuation, phase shift, and waveform distortion of high-frequency signals; The low-frequency balance parameters are used to suppress DC drift, low-frequency noise, and low-frequency impedance imbalance in low-frequency signals. When different geological conditions in the work area cause changes in the receiving frequency, the high-frequency balance parameters and low-frequency balance parameters are reset based on the results of field experiments.

6. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 5, characterized in that: When determining the high-frequency balance parameters, the overlapping area between the seismic detection areas corresponding to multiple broadband signal excitation points is obtained and a calibration area list is generated. Select a near-layer calibration region from the calibration region list, extract high-frequency signal data from the near-layer calibration region, and identify the features of the near-layer region. Based on the near-layer region characteristics, the formation reflection interface of the near-layer calibration region is determined, and the standard stitched waveform corresponding to the formation reflection interface is extracted; The high-frequency signal data corresponding to the broadband signal excitation point is compared with the standard spliced ​​waveform. Based on the comparison results, the circuit adjustment range of the high-frequency link is deduced, and the high-frequency balance parameters are determined within the circuit adjustment range. When determining the low-frequency balance parameters, the high-frequency near-layer region characteristics after calibration with the high-frequency balance parameters are used as constraints to reverse-engineer the propagation law of the low-frequency signal in the strata and generate a standard low-frequency signal. Extract low-frequency signal data corresponding to the calibration area, and perform difference analysis between the low-frequency signal data and the standard low-frequency signal; Based on the difference analysis results, low-frequency link error is extracted, and low-frequency balance parameters are set according to the low-frequency link error. The low-frequency signal is then re-acquired using the set low-frequency balance parameters for verification.

7. The method for receiving broadband seismic exploration signals based on circuit balance according to claim 1, characterized in that: After obtaining the broadband profile, the surface survey data is used to calibrate the broadband profile to the true surface reference plane to form a true surface strata broadband profile. Based on the experimental results of different work areas, the cutoff frequency band settings for low-frequency and high-frequency signals are determined so that the broadband land-based detector can perform low-distortion reception under full broadband reception conditions.

8. A method for receiving broadband seismic exploration signals based on circuit balance according to claim 1, characterized in that: When the receiving frequency of the work area changes due to the influence of the strata, after completing the current work area parameter setting, return to the receiving end frequency parameter adjustment step to reset the parameters. Construction work in the entire work area will be carried out based on the final determined receiver frequency parameters, and the receiver frequency parameters will be dynamically adjusted according to changes in the receiver frequency during the process. The circuit balance theory refers to the fact that in the process of designing and adjusting the receiver circuit, the only evaluation criterion is not whether the traditional circuit forms a conventional loop. Instead, the receiver circuit status is evaluated and the receiver frequency parameters are set based on the balance between the energy conversion state of the piezoelectric components in the broadband land-based detector, the parasitic parameters of the signal output path, the input impedance of the seismic acquisition station, and the fidelity of the broadband signal.

9. A detector, said detector being used to perform a circuit-balanced broadband signal receiving method for seismic exploration as described in any one of claims 1-8, characterized in that: It includes the outer casing, the outer casing cover, the waterproof rubber ring, the tail cone, the movement clamping screw ring, the movement housed inside the outer casing, and the equivalent circuit corresponding to the movement. The tail cone is connected to the lower end of the outer shell and is used to insert into the ground and transmit ground vibrations to the outer shell; The outer cover is fitted onto the upper end of the outer shell, and the waterproof rubber ring is disposed between the outer shell and the outer cover to form a waterproof seal; The mechanism is pressed and fixed inside the outer casing by a mechanism clamping screw ring, and is used to convert the seismic vibration transmitted by the outer casing into a broadband electrical signal; The equivalent circuit is used to characterize the circuit relationship of the mechanism generating broadband electrical signals and outputting broadband electrical signals to the seismic acquisition station under seismic vibration. The mechanism includes a mechanism shell, an outer ring insulating ring, a spacer, an insulating washer, a top cover, and piezoelectric components; The outer ring insulating ring, spacer, insulating gasket, top cover, and piezoelectric components are disposed inside the mechanism housing; The piezoelectric components are clamped in the mounting space formed by the core housing and the top cover, and are electrically insulated from the core housing by an outer ring insulating ring, a spacer and an insulating washer. The piezoelectric element is used to generate a broadband electrical signal corresponding to the vibration acceleration under the seismic vibration transmitted by the tail cone and shell.

10. The detector according to claim 9, characterized in that: The equivalent circuit includes a piezoelectric equivalent signal source, a piezoelectric equivalent capacitor, an insulating support equivalent impedance, a detector output terminal, and an input impedance of the seismic acquisition station. The piezoelectric equivalent signal source is used to equivalently represent the electrical signal generated by the piezoelectric element under seismic vibration. The piezoelectric equivalent capacitance is used to represent the capacitance characteristics of the piezoelectric component itself. The equivalent impedance of the insulating support is used to equivalently represent the insulating isolation relationship formed by the outer ring insulating ring, the spacer, and the insulating washer; The output of the detector is used to connect to the input of the seismic acquisition station. The input impedance of the seismic acquisition station is used to form a broadband signal acquisition relationship with the piezoelectric equivalent signal source, piezoelectric equivalent capacitance, and insulating support equivalent impedance after the detector is connected to the seismic acquisition station; The equivalent circuit satisfies the circuit balance relationship, which is the energy and signal balance suitable for broadband reception formed between the mechanical energy to electrical signal conversion of piezoelectric components, the energy storage and release of piezoelectric equivalent capacitors, the isolation effect of the insulating support equivalent impedance, the signal transmission at the detector output end, and the receiving effect of the input impedance of the seismic acquisition station. By balancing the circuit, the detector can output a low-distortion broadband electrical signal when connected to an existing seismic acquisition station.

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