Buried hill structure identification method based on fusion of gravity, magnetic, electric and seismic exploration technologies

Abstract

The present application provides a buried hill structure identification method based on the fusion of gravity-magnetic-electromagnetic-seismic exploration technology, comprising: step 1, establishing a rock and stratum geology-geophysical model to clarify the geophysical basis for buried hill structure identification; step 2, performing fine processing and inversion of gravity and magnetic data, separating and extracting buried hill structure gravity and magnetic anomalies, and obtaining three-dimensional apparent density and apparent magnetic susceptibility bodies of the buried hill structure by inversion; step 3, performing fine processing and inversion of electromagnetic data to obtain a depth domain apparent resistivity profile; step 4, performing post-stack seismic processing and gravity-magnetic-electromagnetic low-frequency model constrained inversion to obtain a wave impedance inversion profile; and step 5, performing mutual verification of gravity-magnetic-electromagnetic-seismic to implement the buried hill geological target. The buried hill structure identification method based on the fusion of gravity-magnetic-electromagnetic-seismic exploration technology promotes the development of current buried hill oil and gas exploration technology, fully utilizes the advantages of various exploration technologies, improves the identification accuracy and reliability of buried hill geological targets, and provides a geophysical basis for buried hill oil and gas exploration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of processing, inversion and comprehensive interpretation of geophysical data such as gravity, magnetic, electric and seismic data in oil and gas exploration, and particularly relates to a buried hill structure identification method based on integration of gravity, magnetic, electric and seismic exploration technologies. BACKGROUND

[0002] Gravity, magnetic, electromagnetic and artificial source seismic geophysical exploration methods are based on density, magnetic susceptibility, resistivity and velocity detection data to reflect different geophysical properties of underground rocks. With the increasing complexity of oil and gas exploration targets and the increasing difficulty of exploration, relying on single geophysical data will have multiple solutions, therefore, integrating various geophysical data, maximizing the advantages of various data, and enabling these data to verify and complement each other, can clearly and accurately reveal the underground structure characteristics, and provide reliable geophysical basis for oil and gas exploration.

[0003] The exploration degree of Jiyang Depression in Bohai Bay Basin is very mature, and finding deep buried hill oil and gas targets is a new direction for future exploration. However, the accumulation conditions are controlled by many geological factors, and only the buried hill structure identification is very difficult. With the progress of oil and gas exploration technology, it is inevitable to integrate the results of comprehensive gravity, magnetic, electric and seismic exploration technologies to accurately reveal the buried hill structure and the inside story.

[0004] In the Chinese patent application with the application number 201610496730.4, a buried hill reservoir seismic identification method based on mixed dip angle scanning amplitude change rate is involved, the method comprising: applying multi-channel coherence algorithm in time domain to estimate the dip angle value of stratum; applying the time delay of stratum dip angle on seismic record to estimate the dip angle of stratum based on the time delay characteristics of Fourier transform; based on time-frequency domain mixed dip angle scanning, calculating the spatial change rate of average absolute amplitude in time window along the dip angle of stratum on the basis of local layer flattening; according to the average absolute amplitude spatial change rate data body, through well-to-well profile and along-layer slice, the seismic identification method for studying the buried hill inside pore and fracture type reservoir is researched. The method can eliminate the influence of interface dip angle, highlight the change of seismic wave at the position of pore and fracture reservoir, and provide more abundant and reliable information for identification of pore and fracture type buried hill reservoir.

[0005] In the Chinese patent application No. 201910216726.1, a method for predicting Paleozoic buried hill reservoir based on structure-oriented filtering is disclosed, which comprises the following steps: calculating the dip angle guide volume based on the original seismic data; filtering the original seismic data volume by using the dip angle guide volume to form a structure-oriented filter volume; calculating the residual volume between the original seismic data and the structure-oriented filter volume; and extracting the amplitude attribute graph of the residual volume of the top surface of the Paleozoic buried hill to represent the distribution of the weathering crust reservoir at the top of the Paleozoic buried hill. The method provides favorable support for the description of the favorable trap of the Paleozoic buried hill reservoir, and has important reference significance for predicting the Paleozoic buried hill reservoir in a faulted basin.

[0006] In the Chinese patent application No. CN202010008590.8, a method for predicting buried hill fracture reservoir is disclosed, which comprises the following steps: step 1, carrying out fault enhancement processing on post-stack seismic data to highlight the characteristics of buried hill faults; step 2, extracting a disorder attribute according to the seismic data after the fault enhancement processing; step 3, carrying out waveform indication inversion of the buried hill fracture reservoir based on pure wave seismic data; step 4, carrying out frequency analysis on the extracted seismic disorder data and the waveform indication inversion result, and selecting an advantage frequency for frequency domain fusion; and step 5, carrying out cross analysis on the fused data body and the logging interpretation result to interpret the fracture reservoir.

[0007] The above prior art has great difference from the present application, and cannot solve the technical problems we want to solve. Therefore, we have invented a new buried hill structure identification method based on the fusion of gravity-magnetic-electric-seismic exploration technology. SUMMARY

[0008] The purpose of the present application is to provide a buried hill structure identification method based on the fusion of gravity-magnetic-electric-seismic exploration technology, which fully utilizes the advantages of various exploration technologies and improves the identification accuracy and reliability of buried hill geological targets.

[0009] The purpose of the present application can be achieved by the following technical measures: a buried hill structure identification method based on the fusion of gravity-magnetic-electric-seismic exploration technology, which comprises the following steps:

[0010] Step 1, establishing a rock and stratum geology-geophysical model to clarify the geophysical basis for identifying buried hill structures;

[0011] Step 2, carrying out fine processing and inversion of gravity and magnetic data, separating and extracting buried hill structure gravity and magnetic anomalies, and inverting to obtain a three-dimensional apparent density volume and an apparent magnetic susceptibility volume of the buried hill structure;

[0012] Step 3, carrying out fine processing and inversion of electromagnetic data to obtain a depth domain apparent resistivity profile;

[0013] Step 4, post-stack seismic processing and gravity-magnetic-electric low-frequency model constrained inversion are carried out to obtain wave impedance inversion profile;

[0014] Step 5, gravity-magnetic-electric seismic mutual verification is carried out to implement buried hill geological targets.

[0015] The purpose of the application can also be realized by the following technical measures:

[0016] In step 1, the drilling and logging data of the research area and the geophysical test results of the drilling core samples are collected, and the stratum and rock geophysical rules are counted.

[0017] In step 1, the collected geophysical test results and the counted stratum and rock geophysical rules include density, magnetic susceptibility, resistivity and velocity.

[0018] In step 2, gravity-magnetic data fine processing is carried out, and technical means such as round smoothing filter and low-pass filter are used to eliminate accidental errors and random interference caused by shallow inhomogeneous bodies in the data acquisition process.

[0019] In step 2, gravity-magnetic field source separation is carried out, gravity-magnetic forward is carried out according to the seismic horizon interpretation results, and gravity-magnetic anomaly of buried hill structure is extracted by stripping.

[0020] In step 2, gravity-magnetic inversion is carried out to obtain three-dimensional apparent density body and three-dimensional apparent magnetic susceptibility body of buried hill structure, and the inversion method adopts conjugate gradient and finite element method.

[0021] In step 3, electromagnetic data fine processing and conversion are carried out to obtain frequency-amplitude electrical section, wherein the processing process includes distortion point editing filter, flying point removal, static correction and tensor impedance decomposition.

[0022] In step 3, electromagnetic inversion is carried out to obtain depth domain apparent resistivity profile, and the inversion method adopts OCCAM and nonlinear conjugate gradient.

[0023] In step 4, post-stack seismic data processing is carried out, first, the vertical processing range is determined through the top and bottom of the target layer interpretation, and then the low-frequency dominant frequency band range which needs to be enhanced is determined through typical low-frequency imaging seismic data analysis and research area original data spectrum analysis, then, on this basis, the seismic reconstruction low-frequency signal energy enhancement technology is used to carry out compensation processing, and the imaging effect is improved, finally, the required seismic data of geology and geophysics is obtained.

[0024] In step 4, the heavy magnetic electric low frequency model constrained inversion is carried out, the typical buried hill reflection characteristics of low frequency compensation seismic are combined, the buried hill density and magnetic susceptibility model is finely modeled by referring to the electric inversion profile and the gravity and magnetic anomaly curve, the density and magnetic susceptibility initial model is obtained, the correctness of the forward verification model is verified, the accurate interpretation model is finally obtained by repeated correction, the inversion geological model is constructed, and the sparse pulse inversion is carried out to obtain the wave impedance inversion profile.

[0025] In step 5, the gravity and magnetic electric seismic processing and inversion results are compared and verified, the buried depth and distribution range of the buried hill structure are comprehensively analyzed, and the buried hill geological target is implemented.

[0026] In step 5, first, the initial geological-geophysical model is established according to the inversion results; then, the gravity and magnetic theoretical forward curve is calculated according to the model; then, the theoretical forward curve is compared with the measured data; finally, the geological model is modified and corrected, the physical property parameters of the model are modified, fitting is carried out again, and the process is repeated for many times, when the two are basically coincided, the designed geological model can better reflect the underground geological structure and the formation physical property characteristics.

[0027] The buried hill structure identification method based on the fusion of gravity, magnetic, electric and seismic exploration technologies in the application can accurately find the buried hill exploration geological target based on the fusion of various geophysical data, provide accurate geophysical basis for the buried hill oil and gas exploration, and lay a foundation for the increase of oil and gas reserves and production. The application can effectively find and implement the buried hill geological target in different structural positions, different strata and different lithology, promote the development of the current buried hill oil and gas exploration technology, give full play to the advantages of various exploration technologies, improve the identification accuracy and reliability of the buried hill geological target, provide geophysical basis for the buried hill oil and gas exploration, and reduce the risk of oil and gas exploration. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flow chart of the specific embodiment of the buried hill structure identification method based on the fusion of gravity, magnetic, electric and seismic exploration technologies in the application is shown in the figure.

[0029] Figure 2 The figure is a schematic view of the apparent density body obtained by gravity inversion in example 1 of the application;

[0030] Figure 3 The figure is a schematic view of the electromagnetic measuring line resistivity inversion profile in example 1 of the application;

[0031] Figure 4 The figure is a low frequency constraint wave impedance inversion effect diagram in example 1 of the application;

[0032] Figure 5 The figure is a gravity-seismic constraint verification buried hill structure schematic view in example 1 of the application;

[0033] Figure 6 is a schematic diagram of the gravity-seismic constrained buried hill structure in Example 2 of the present application;

[0034] Figure 7 is a schematic diagram of the electromagnetic profile inversion profile in Example 3 of the present application. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0036] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0037] As shown in Figure 1 , a flow chart of a buried hill structure identification method based on the fusion of gravity-magnetic-electromagnetic-seismic exploration technology of the present application. The buried hill structure identification method based on the fusion of gravity-magnetic-electromagnetic-seismic exploration technology includes the following steps: Figure 1 Step 101, rock, stratum geology-geophysical model establishment, clear the geophysical basis of buried hill structure identification;

[0038] Step 102, fine processing and inversion of gravity and magnetic data, separate and extract buried hill structure gravity and magnetic anomalies, and obtain three-dimensional apparent density volume and three-dimensional apparent magnetic susceptibility volume of buried hill structure by inversion;

[0039] Step 103, fine processing and inversion of electromagnetic data, obtain depth domain apparent resistivity profile;

[0040] Step 104, post-stack seismic data processing and gravity-magnetic-electromagnetic low-frequency model constrained inversion, obtain wave impedance inversion profile;

[0041] Step 105, mutual verification of gravity-magnetic-electromagnetic-seismic, and implementation of buried hill geological target.

[0042] The following are several specific embodiments of the application.

[0043] Example 1:

[0044] In a specific embodiment 1 of the application, the following steps are specifically included:

[0045]

[0046] ​Step (1), collect the drilling and logging data and geophysical (density, magnetic susceptibility, resistivity and velocity) test results of the core samples in the study area, and statistically analyze the stratum and rock geophysical (density, magnetic susceptibility, resistivity and velocity) regularity.

[0047] Step (2), fine processing of gravity and magnetic data, using techniques such as round smoothing filter and low-pass filter to eliminate accidental errors and random interference caused by shallow inhomogeneous bodies in the data acquisition process; gravity and magnetic field source separation, based on the seismic horizon interpretation results, carrying out gravity and magnetic forward, stripping and extracting buried hill structure gravity and magnetic anomaly; carrying out gravity and magnetic inversion, obtaining buried hill structure three-dimensional apparent density body ( Figure 2 ), three-dimensional apparent magnetic susceptibility body, and the inversion method adopts conjugate gradient and finite element method.

[0048] Step (3), fine processing and conversion of electromagnetic data, obtaining frequency-amplitude electrical section, wherein the processing process includes distortion point editing filter, fly point removal, static correction, tensor impedance decomposition, etc.; electromagnetic inversion obtains depth domain apparent resistivity profile ( Figure 3 ), and the inversion method adopts OCCAM method.

[0049] Step (4), post-stack seismic data processing, first determining the vertical processing range through the top and bottom interpretation of the target layer, and determining the low-frequency dominant band range that needs to be enhanced through typical low-frequency imaging seismic data analysis and spectrum analysis of the original data in the study area, then using the seismic reconstruction low-frequency signal energy enhancement technology to carry out compensation processing, improving the imaging effect, and finally obtaining the seismic data required by geology and geophysics. Low-frequency model constrained inversion of gravity, magnetic and electric, combined with the typical buried hill reflection characteristics of low-frequency compensated seismic, and referring to the electromagnetic inversion profile and gravity and magnetic anomaly curve, fine modeling of buried hill density and magnetic susceptibility model is carried out, and the initial model of density and magnetic susceptibility is obtained, and the correctness of the forward verification model is verified. Repeat the correction, and finally obtain the accurate interpretation model, build the inversion geological model, and use the inversion software to carry out sparse pulse inversion, and obtain the wave impedance inversion profile ( Figure 4 ).

[0050] Step (5), comparison and verification of the processing and inversion results of gravity, magnetic, electric and seismic, comprehensive analysis of the buried depth and distribution range of buried hill structure, and implementation of buried hill geological target. First, according to the inversion results, the initial geological-geophysical model is established; then the gravity and magnetic theoretical forward curve is calculated according to the model; then the theoretical forward curve is compared with the measured data; finally, the geological model is modified and corrected, the physical property parameters of the model are modified, and the fitting is carried out again, and the process is repeated for many times, when the two are basically coincided, the designed geological model can better reflect the underground geological structure and stratum physical property characteristics ( Figure 5 ).

[0051] Example 2:

[0052] In the specific embodiment 2 of the application, the following steps are specifically included:

[0053] Step (1), collect the geophysical (density, resistivity and velocity) test results of the drilling and logging data and drilling core samples in the study area, and statistically analyze the formation and rock geophysical (density, resistivity and velocity) rules.

[0054] Step (2), fine processing of gravity data, using techniques such as smoothing filter and low-pass filter to eliminate accidental errors and random interference caused by shallow heterogeneous bodies in the data acquisition process; gravity field source separation, based on the seismic horizon interpretation results, carrying out gravity forward, stripping and extracting buried hill structure gravity anomaly; carrying out gravity inversion to obtain buried hill structure three-dimensional apparent density body, and the inversion method uses finite element method, etc.

[0055] Step (3), fine processing and conversion of electromagnetic data, obtaining frequency-amplitude electrical section, wherein the processing process includes distortion point editing filter, fly point removal, static correction, tensor impedance decomposition, etc.; electromagnetic inversion obtains depth domain apparent resistivity profile, and the inversion method uses nonlinear conjugate gradient, etc.

[0056] Step (4), post-stack seismic data processing, first determining the vertical processing range through the top and bottom interpretation of the target layer, and determining the low-frequency dominant band range that needs to be enhanced through typical low-frequency imaging seismic data analysis and spectrum analysis of the original data in the study area, then on this basis, using seismic reconstruction low-frequency signal energy enhancement technology to carry out compensation processing, improving the imaging effect, finally obtaining the seismic data required by geology and geophysics. Low-frequency model constrained inversion, combined with the typical buried hill reflection characteristics of low-frequency compensated seismic, and referring to the electrical inversion profile and gravity anomaly curve, fine modeling of the buried hill density model is carried out to obtain the initial density model, and the correctness of the forward verification model is verified. Repeat the correction to finally obtain an accurate interpretation model, build an inversion geological model, and use inversion software to carry out sparse pulse inversion to obtain wave impedance inversion profile.

[0057] Step (5), comparison and verification of the results of gravity, electricity and seismic processing and inversion, comprehensive analysis of the buried depth and distribution range of the buried hill structure, and implementation of the buried hill geological target. First, according to the inversion results, the initial geological-geophysical model is established by comprehensive comparison; then the gravity theoretical forward curve is calculated according to the model; then the theoretical forward curve is compared with the measured data; finally, the geological model is modified and corrected, the physical property parameters of the model are modified, and the fitting is carried out again, and the process is repeated for many times. When the two are basically coincided, the designed geological model can better reflect the underground geological structure and formation physical property characteristics. Figure 6 ).

[0058] Embodiment 3:

[0059] In the specific embodiment 3 of the application, the following steps are specifically included:

[0060] Step (1), collect the geophysical (density, magnetic susceptibility, resistivity and velocity) test results of the drilling and logging data and drilling core samples in the study area, and statistically analyze the stratum and rock geophysical (density, magnetic susceptibility, resistivity and velocity) regularity.

[0061] Step (2), fine processing of gravity and magnetic data, using techniques such as round filter and low-pass filter to eliminate accidental errors and random interference caused by shallow heterogeneous bodies in the data acquisition process; gravity and magnetic source separation, based on the seismic horizon interpretation results, carrying out gravity and magnetic forward, stripping and extracting buried hill structure gravity and magnetic anomaly; carrying out gravity and magnetic inversion, obtaining buried hill structure three-dimensional apparent density body and three-dimensional apparent magnetic susceptibility body, and the inversion method adopts conjugate gradient and finite element method.

[0062] Step (3), fine processing and conversion of electromagnetic data, obtaining frequency-amplitude electrical section, wherein the processing process includes distortion point editing filter, flight point removal, static correction, tensor impedance decomposition, etc.; electromagnetic inversion obtains depth domain apparent resistivity profile Figure 7 ), and the inversion method adopts OCCAM method.

[0063] Step (4), post-stack seismic data processing, first determining the vertical processing range through the top and bottom interpretation of the target layer, and determining the low-frequency dominant band range that needs to be enhanced through typical low-frequency imaging seismic data analysis and regional raw data spectrum analysis, then on this basis, using seismic reconstruction low-frequency signal energy enhancement technology to carry out compensation processing, improving the imaging effect, finally obtaining the seismic data required by geology and geophysics. Low-frequency model constrained inversion of gravity, magnetic and electric, combined with the typical buried hill reflection characteristics of low-frequency compensated seismic, and referring to the electromagnetic inversion profile and gravity anomaly curve, fine modeling of buried hill density and magnetic susceptibility model is carried out, and the initial model of density and magnetic susceptibility is obtained, and the correctness of the forward verification model is verified. Repeat the correction, finally get the accurate interpretation model, build the inversion geological model, use the inversion software to carry out sparse pulse inversion, and obtain the wave impedance inversion profile.

[0064] Step (5), comparison and verification of gravity, magnetic, electric and seismic processing and inversion results, comprehensive analysis of the buried depth and distribution range of buried hill structure, and implementation of buried hill geological target. First, according to the inversion results, the initial geological-geophysical model is established; then the gravity and magnetic theoretical forward curve is calculated according to the model; then the theoretical forward curve is compared with the measured data; finally, the geological model is modified and corrected, the physical property parameters of the model are modified, and the fitting is carried out again. Repeat several times, when the two are basically coincided, the designed geological model can better reflect the underground geological structure and stratum physical property characteristics.

[0065] The buried hill structure identification method based on the gravity-magnetic-electric-seismic exploration technology fusion in the application, on the basis of gravity, magnetic, electric, seismic fine processing and inversion, plays the exploration advantages of various geophysical data, fuses multiple geophysical data, accurately discovers buried hill exploration geological targets, provides accurate geophysical basis for buried hill oil and gas exploration, and lays a foundation for oil and gas reserve increase and production increase.

[0066] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the foregoing detailed description of the application is made with reference to the foregoing examples, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0067] In addition to the technical features described in the specification, they are known to those skilled in the art.

Claims

1. A buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies, characterized in that, This buried hill structure identification method, which integrates gravity, magnetic, and seismic exploration technologies, includes: Step 1: Establish a geological-geophysical model of rocks and stratigraphy to clarify the geophysical basis for identifying buried hill structures; Step 2: Perform fine processing and inversion of gravity and magnetic data, separate and extract gravity and magnetic anomalies of buried hill structures, and invert to obtain the three-dimensional apparent density volume and apparent magnetic susceptibility volume of buried hill structures; Step 3: Perform fine processing and inversion of electromagnetic data to obtain the apparent resistivity profile in the depth domain; Step 4: Based on the low-frequency model constrained by gravity, magnetoelectricity, and seismic impedance inversion, the three-dimensional apparent density volume, apparent magnetic susceptibility volume, and resistivity volume are used as low-frequency constraint models to carry out sparse pulse inversion. Combining the impedance inversion results constrained by the low-frequency model, and referring to the electrical inversion profile and gravity and magnetic anomaly curves, fine modeling of the density and magnetic susceptibility models of buried hills is carried out to obtain the initial density and magnetic susceptibility models. Forward modeling is then carried out to verify the correctness of the models. This process is repeated to obtain an accurate interpretation model. Step 5: Conduct mutual verification of gravity, magnetic field, electric field, and seismic activity to confirm the geological targets of the buried hill.

2. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 1, characterized in that, In step 1, we collect drilling and logging data and geophysical test results of drilling core samples in the study area, and statistically analyze the geophysical laws of the strata and rocks.

3. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 2, characterized in that, In step 1, the collected geophysical test results and statistical analysis of stratigraphic and rock geophysical laws include density, magnetic susceptibility, resistivity, and velocity.

4. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 1, characterized in that, In step 2, the gravity and magnetic data are finely processed, and techniques such as smoothing filtering and low-pass filtering are used to eliminate accidental errors and random interference caused by shallow inhomogeneities during the data acquisition process.

5. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 4, characterized in that, In step 2, gravity and magnetic field sources are separated, and gravity and magnetic forward modeling is carried out based on the seismic stratigraphic interpretation results to extract gravity and magnetic anomalies of buried hill structures.

6. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 5, characterized in that, In step 2, gravity and magnetic inversion is carried out to obtain the three-dimensional apparent density volume and three-dimensional apparent magnetic susceptibility volume of the buried hill structure. The inversion method adopts the conjugate gradient and finite element method.

7. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 1, characterized in that, In step 3, the electromagnetic data is finely processed and converted to obtain the frequency-amplitude electrical profile. The processing includes distortion point editing and filtering, flypoint removal, static correction, and tensor impedance decomposition.

8. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 7, characterized in that, In step 3, electromagnetic inversion is performed to obtain the apparent resistivity profile in the depth domain. The inversion method used is OCCAM and nonlinear conjugate gradient.

9. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 1, characterized in that, In step 4, post-stack seismic data processing is first performed. The vertical processing range is determined by interpreting the top and bottom of the target layer. At the same time, the range of low-frequency dominant frequency bands that need to be enhanced is determined by analyzing typical low-frequency imaging seismic data and the spectrum analysis of the original data of the study area. Then, on this basis, the seismic reconstruction low-frequency signal energy enhancement technology is used to carry out compensation processing to improve the imaging effect. Finally, the seismic data required for the constraint inversion of the gravity, magnetoelectric and low-frequency model is obtained.

10. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 1, characterized in that, In step 5, gravity, magnetic, electromagnetic and seismic processing and inversion results are compared and verified, and the burial depth and distribution range of the buried hill structure are comprehensively analyzed to realize the geological objectives of the buried hill.

11. The buried hill structure identification method based on the fusion of gravity, magnetic, electromagnetic, and seismic exploration technologies according to claim 10, characterized in that, In step 5, a geological-geophysical initial model is first established based on the comprehensive comparison of the inversion results; then, the gravity and magnetic theoretical forward modeling curve is calculated based on the model; then, the theoretical forward modeling curve is compared with the measured data; finally, the geological model is modified and corrected, the physical property parameters of the model are corrected, and the model is fitted again. This process is repeated multiple times. When the two coincide, the designed geological model can reflect the underground geological structure and stratigraphic physical property characteristics.

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