Method and device for researching influence of karst cave change on earthquake response by utilizing forward modeling simulation

Abstract

The invention provides a method and a device for researching influence of karst cave change on earthquake response by utilizing forward modeling simulation. According to the method, two-dimensional numerical models of karst caves with different scales and forms are constructed, finite element forward modeling is carried out, seismic response differences caused by form and scale changes are compared and analyzed from the aspects of amplitude, waveform, frequency and the like, the influence degree of the form and scale changes of the karst caves on a wave field is cleared, certain quantitative cognition is formed, and the method is suitable for mass production. Therefore, an effective foundation support is provided for efficient development of the carbonate fractured-vuggy reservoir.

Description

Technical Field

[0001] The present invention relates to the field of applied geophysical seismic exploration technology, and more specifically, to a method and device for studying the influence of cave changes on seismic response by forward simulation. Background Art

[0002] In recent years, with the deepening of exploration work, the exploration objects are shifting from simple to complex, from shallow to deep, and deep and complex fault block oil and gas exploration has become the main direction, and the difficulty of exploration is increasing. This type of deep oil reservoir has complex burial conditions, extreme geological environment, poor formation development, and complex and diverse seismic wave field responses. Exploration in this environment faces huge challenges, which seriously restricts the efficiency and success rate of exploration. New theories and new technologies are urgently needed to guide the new round of oil and gas exploration.

[0003] Carbonate rock is one of the important growth points of oil and gas exploration in my country, and it contains rich oil and gas resources. However, the fracture-cave oil and gas reservoirs developed in it are characterized by deep burial and complex filling, which causes great uncertainty in their accurate description and evaluation. The complexity of fracture-cave reservoir space mainly comes from the following aspects: 1) Deep burial makes it difficult to effectively identify by technical means such as seismic wave logging; 2) The components of sand bodies, shales, water bodies, etc. in the filling are complex, with large differences in spatial distribution, making description difficult; 3) The scale and morphology of the caves vary greatly, and the mechanism of their influence on seismic response is unclear. The combination of the above difficulties has made it impossible for us to clearly evaluate the spatial distribution status, production capacity level and optimal development plan of the carbonate oil and gas resources, bringing huge exploration investment risks. Solving the uncertainty of the description of reservoir complexity is an important scientific issue to improve the success rate of carbonate oil and gas exploration and guide efficient development.

[0004] Although a large number of forward modeling studies have been carried out on different types of fracture-vuggy reservoirs and certain results have been achieved, most of the analysis methods are based on post-stack attributes, the analysis methods are relatively simple, and the information mining is not sufficient.

[0005] Therefore, there is an urgent need for a technical solution that can clarify the impact of cave morphology and scale changes on the wave field and form a certain quantitative understanding. Summary of the invention

[0006] In view of this, the present invention discloses a method for studying the influence of cave changes on seismic response by forward simulation, so as to clarify the wave field change law caused by morphological and scale differences.

[0007] According to one aspect of the present invention, a method for studying the influence of cave changes on seismic response using forward modeling is proposed, comprising the following steps:

[0008] Step 1, establishing a two-dimensional stratigraphic framework model, wherein the model includes multiple sets of main stratigraphic layers;

[0009] Step 2, setting a plurality of groups of caves with different scales and shapes in the target layer of the stratigraphic framework model;

[0010] Step 3, conducting finite element numerical simulation on the two-dimensional geological model to obtain simulated single shot data;

[0011] Step 4, performing prestack depth migration processing on the simulated single shot data;

[0012] Step 5: Compare and analyze the seismic response characteristics of the data after migration processing to obtain the relationship between the size and shape of the cave and the seismic response characteristics.

[0013] In some embodiments, the different shapes include square, circle, and irregular shape.

[0014] In some implementations, in step 4, a Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on the simulated single shot data.

[0015] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0016] According to another aspect of the present invention, a device for studying the influence of cave changes on seismic response by forward modeling is proposed, comprising:

[0017] A model building unit, used for building a two-dimensional stratigraphic framework model, wherein the model includes a plurality of sets of main stratigraphic layers;

[0018] The karst cave setting unit is used to set multiple groups of karst caves with different scales and shapes in the target layer of the stratigraphic framework model;

[0019] Finite element numerical simulation unit, used to carry out finite element numerical simulation on two-dimensional geological model and obtain simulated single shot data;

[0020] A pre-stack depth migration processing unit is used to perform pre-stack depth migration processing on simulated single shot data;

[0021] The seismic response analysis unit is used to compare and analyze the seismic response characteristics of the data after migration processing, and obtain the relationship between the scale and shape of the cave and the seismic response characteristics.

[0022] In some embodiments, the different shapes include square, circle, and irregular shape.

[0023] In some embodiments, in the prestack depth migration processing unit, a Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on simulated single shot data.

[0024] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0025] According to another aspect of the present invention, an electronic device is also provided, the electronic device comprising:

[0026] A memory storing executable instructions;

[0027] A processor runs the executable instructions in the memory to implement the method described above for studying the influence of cave changes on seismic response by forward modeling.

[0028] According to another aspect of the present invention, a computer-readable storage medium is also proposed, which stores a computer program. When the computer program is executed by a processor, the method described above for studying the influence of cave changes on seismic response using forward simulation is implemented.

[0029] The present invention provides a method for studying the influence of cave scale and morphological changes on seismic response by forward modeling. By constructing two-dimensional numerical models of caves of different scales and morphologies and performing finite element forward modeling, the differences in seismic response caused by morphological and scale changes are compared and analyzed from multiple perspectives such as amplitude, waveform, and frequency, and the influence of cave morphological and scale changes on the wave field is clarified, and a certain quantitative understanding is formed, thereby providing effective basic support for the efficient development of carbonate fracture-cave reservoirs. The advantages of this technical solution are further analyzed in detail below.

[0030] 1. A quantitative cave scale-morphology-seismic response characteristic relationship model was established to achieve the prediction and transplantation of the response of complex carbonate oil and gas reservoirs.

[0031] 2. The introduction of the finite element forward numerical realization algorithm ensures the accuracy and reliability of the simulation results and significantly improves the simulation accuracy.

[0032] 3. Kirchhoff migration processing technology based on ray tracing theory makes target depiction more accurate and clear.

[0033] Fourth, the influence of reservoir cave scale and morphological changes on seismic response is revealed, enriching the theoretical understanding of wave field propagation mechanism.

[0034] 5. Multi-angle analysis methods increase the dimension of feature extraction and provide a reliable basic support for the efficient development of carbonate oil and gas reservoirs.

[0035] 6. The forward simulation and attribute analysis process provides a technical example for the study of deep and complex oil and gas reservoirs and can be widely applied.

[0036] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0038] Figure 1 A flow chart of a method for studying the influence of cave changes on seismic response by forward simulation according to an embodiment of the present invention is shown.

[0039] Figure 2 A schematic diagram of a two-dimensional stratigraphic framework model established according to an exemplary embodiment of the present invention is shown.

[0040] Figure 3 A schematic diagram showing mesh generation results of caves of different shapes according to an exemplary embodiment of the present invention is shown.

[0041] Figure 4 A schematic diagram of prestack depth migration results of caves with different scales and shapes according to an exemplary embodiment of the present invention is shown.

[0042] Figure 5 (a), (b), and (c) are schematic diagrams showing root mean square amplitudes of caves of different scales and shapes according to an exemplary embodiment of the present invention.

[0043] Figure 6 (a), (b), and (c) are schematic diagrams showing waveforms and spectra of caves of different scales and shapes according to an exemplary embodiment of the present invention.

[0044] Figure 7 The time-frequency spectra of caves with different scales and morphologies according to an exemplary embodiment of the present invention are shown. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0046] Example 1

[0047] Figure 1 A flow chart of a method for studying the influence of cave changes on seismic response by forward modeling according to an embodiment of the present invention is shown. As shown in the figure, the method includes steps 1 to 5.

[0048] Step 1: Establish a two-dimensional stratigraphic framework model, which includes multiple sets of main stratigraphic layers.

[0049] The scope and depth of the study area can be determined first.

[0050] Then, based on the logging interpretation data, the thickness, velocity and density parameters of the main strata are determined. In order to facilitate analysis, the strata in the study area are appropriately simplified to improve the calculation efficiency. In one embodiment, the model may include 4 sets of main strata. Elastic parameters of the strata and surrounding rocks can then be set.

[0051] The stratigraphic framework model used in this scheme contains multiple sets of stratigraphic layers and has the following advantages:

[0052] Close to the actual geological conditions, the stratigraphic structure in reality is complex and changeable, and a simple single-layer or two-layer model often cannot fully reflect the authenticity of the geological body. Using multiple sets of stratigraphic units can make the results of numerical simulation more in line with reality;

[0053] It is helpful to analyze the propagation characteristics of seismic waves in each layer. The multi-layer geological model can simulate the reflection, refraction, and conversion of seismic waves in strata with different speeds, which is very important for analyzing and interpreting simulation results.

[0054] Improve the complexity of the simulation scene. In reality, geological structures and media changes are complex, and multi-layer models can provide richer information to reveal the laws.

[0055] To lay the foundation for further research in the future, the ultimate goal of this study is to provide support for the efficient development of carbonate oil and gas reservoirs. The complex multi-layer model is conducive to obtaining richer simulation results and providing a solid foundation for the next step of research.

[0056] In step 2, multiple groups of caves with different scales and shapes are set in the target layer of the stratigraphic framework model.

[0057] In some embodiments, the different shapes include square, circle, and irregular shape.

[0058] For example, in one example, three groups of nine caves of different scales and shapes were designed in the target layer of the stratigraphic framework model. The scales were 900 m2, 1600 m2 and 2500 m2, and the shapes were square, circular and irregular.

[0059] By setting up multiple groups of caves of different scales and shapes in the target layer, we can study the impact of cave size on seismic response, and also study the impact of various cave shapes on seismic response. In addition, different scale characteristics and different morphological characteristics can be combined for research, increasing the sample size and making the results more convincing, so as to conduct a richer and more comprehensive comparative analysis, laying a solid foundation for further in-depth research.

[0060] Step 3: Perform finite element numerical simulation on the two-dimensional geological model to obtain simulated single shot data.

[0061] Finite element numerical simulation mainly includes two parts: mesh generation and numerical simulation.

[0062] Meshing is the pre-processing part of finite element simulation. According to the complexity of the geological model, it is divided into a large number of units, which are connected together through nodes to form a computational grid. The higher the fitting accuracy of the complex boundary, the higher the accuracy of the subsequent simulation. Compared with the regular grid of finite difference, the finite element grid can better adapt to the boundary conditions of complex shapes. For example, when dividing circular caves and irregular caves, the finite element grid can be closer to the actual shape of the cave, so the simulation accuracy is higher.

[0063] In one example, mesh generation may include:

[0064] Import model geometry and import the designed 2D or 3D geological model into finite element analysis software;

[0065] Set material properties and divide the stratum properties according to the material type of each stratum area;

[0066] Generate a mesh, automatically or manually mesh the model area into many small triangular or tetrahedral elements;

[0067] Set the mesh density and appropriately encrypt the mesh according to the boundary and interface shape to improve accuracy, such as encrypting around caves.

[0068] Check the mesh quality to ensure that the mesh continuity is good, there is no unreasonable distortion or gap, and correct the non-compliant mesh.

[0069] After completing the finite element meshing, physical parameters can be assigned to each unit, initial boundary conditions can be set, and then the simulation program can be run to solve the wave equation or other physical equations to obtain the required field quantities, such as numerical solutions of displacement, stress, strain, etc.

[0070] In one example, the numerical simulation may specifically include:

[0071] Import mesh model, import the model including mesh and properties generated in mesh generation;

[0072] Set the excitation source, set the location of the source point according to the actual situation, define the wave source time function (such as Ricker wave), etc.

[0073] Define medium parameters, define elastic parameters such as density and Lamé parameters of each medium area in the model;

[0074] Set absorbing boundaries and set absorbing boundary conditions at the model boundaries to avoid artificial boundary reflection problems;

[0075] Define the detector layout and set the distribution form and type of the detector according to the actual situation;

[0076] Select a solution, choose the finite element solution method based on the wave equations, and determine parameters such as iteration accuracy and step size.

[0077] Run the solver and automatically perform multiple steps of calculations by calling the finite element solver to obtain the required displacement field results.

[0078] Extract wave field data, perform data extraction on simulated wave fields, and simulate single shot data.

[0079] This embodiment adopts finite element numerical simulation, which significantly improves the simulation accuracy.

[0080] Step 4: Perform pre-stack depth migration processing on the simulated single shot data.

[0081] Prestack depth migration processing can improve the signal-to-noise ratio, increase the effective signal strength, increase the temporal resolution of the formation reflection coefficient, improve energy aggregation and enhance the continuity of effective reflection events, correct the impact of dynamic correction stretching, ensure the true position of formations and structural features, and provide depth profile images close to the true velocity, providing a basis for subsequent seismic interpretation and quantitative feature analysis.

[0082] In some embodiments, the Kirchhoff prestack depth migration method may be used to perform prestack depth migration processing on the simulated single shot data.

[0083] The Kirchhoff prestack depth migration method is based on the Kirchhoff integration method. It regards seismic records as signals reflected from underground reflection points. By performing reverse time migration on the seismic records, a depth image of the underground geological structure is obtained. This method has high computational efficiency and can be applied to situations with complex geological structures and changes in underground media.

[0084] The following is a brief introduction to the steps of the Kirchhoff prestack depth migration method:

[0085] 1) Data preprocessing

[0086] The seismic records are pre-processed by denoising, filtering, etc. to improve the quality and resolution of the signal.

[0087] 2) Establishing the initial velocity-depth model

[0088] The initial velocity-depth model is established based on the unstacked data (such as common center point gathers or common shot point gathers) using methods such as coherent inversion.

[0089] 3) Ray tracing

[0090] According to the initial velocity-depth model, the propagation path and travel time of each ray are calculated using the ray tracing algorithm.

[0091] 4) Offset processing

[0092] Based on the results of ray tracing, the seismic records are offset to obtain a depth image of the underground geological structure.

[0093] This implementation adopts the Kirchhoff prestack depth migration method to perform prestack depth migration processing on simulated single-shot data, which is applicable to complex geological structures and has high calculation efficiency.

[0094] Step 5: Compare and analyze the seismic response characteristics of the data after migration processing to obtain the relationship between the size and shape of the cave and the seismic response characteristics.

[0095] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0096] An imaging section refers to a seismic record section after depth migration, which shows the general shape of the strata and geological anomalies.

[0097] The root mean square amplitude of the beads at time t0 refers to the square root of the average of the squares of the amplitudes.

[0098] The waveform of the center channel of the bead is obtained by selecting the seismic channel at the center of the bead for waveform and spectrum analysis. The spectrum is obtained through Fourier transform.

[0099] The frequency-divided instantaneous amplitude attribute refers to calculating the square root of the total energy of the seismic signal at a certain moment from the seismic record after bandpass filtering, and observing the signal characteristics of different frequency bands.

[0100] Time-frequency spectrum refers to the application of continuous wavelet transform to display the joint distribution of signals in the time domain and frequency domain, and observe the time-frequency characteristics of the signal.

[0101] In some embodiments, the root mean square amplitude may be calculated according to the following formula:

[0102]

[0103] Where N is the number of sampling points; a i is the amplitude value at each sampling point.

[0104] According to this embodiment, the relationship between the size and shape of the cave and the seismic response characteristics is obtained, that is, the influence of the size and shape changes of the cave on the seismic response is obtained, which has at least the following important significance:

[0105] A seismic feature library for cave detection and identification can be established, and the seismic response laws corresponding to different types of caves provide a basis for identification, classification and efficient interpretation;

[0106] It is helpful to evaluate the detection difficulty of caves of different scales and shapes, and to clarify which types of caves are easier to be discovered and explained;

[0107] Provide a basis for performance optimization, compare the effects of different measurement arrangements, data processing and interpretation workflows, and select the optimal workflow;

[0108] Develop cost-effective acquisition plans, and rationally design the parameters and extent of data acquisition based on the significance of the differences in response characteristics;

[0109] This embodiment provides a method for studying the influence of cave scale and morphological changes on seismic response by forward modeling. This embodiment constructs two-dimensional numerical models of caves of different scales and morphologies, and performs finite element forward modeling to compare and analyze the differences in seismic response caused by morphological and scale changes from multiple perspectives such as amplitude, waveform, and frequency, clarify the influence of cave morphological and scale changes on the wave field, and form a certain quantitative understanding, thereby providing effective basic support for the efficient development of carbonate fracture-cave reservoirs.

[0110] Example 2

[0111] According to one embodiment of the present invention, a device for studying the influence of cave changes on seismic response by forward simulation includes:

[0112] A model building unit, used for building a two-dimensional stratigraphic framework model, wherein the model includes a plurality of sets of main stratigraphic layers;

[0113] The karst cave setting unit is used to set multiple groups of karst caves with different scales and shapes in the target layer of the stratigraphic framework model;

[0114] Finite element numerical simulation unit, used to carry out finite element numerical simulation on two-dimensional geological model and obtain simulated single shot data;

[0115] A pre-stack depth migration processing unit is used to perform pre-stack depth migration processing on simulated single shot data;

[0116] The seismic response analysis unit is used to compare and analyze the seismic response characteristics of the data after migration processing, and obtain the relationship between the scale and shape of the cave and the seismic response characteristics.

[0117] In some embodiments, the different shapes include square, circular and irregular shapes. For example, in one example, 3 groups of 9 caves of different scales and shapes are designed in the target layer of the stratigraphic framework model, with scales of 900 m2, 1600 m2 and 2500 m2, respectively, and shapes of square, circular and irregular shapes, respectively.

[0118] In some embodiments, in the prestack depth migration processing unit, a Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on simulated single shot data.

[0119] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0120] This embodiment provides a device for studying the influence of cave scale and morphological changes on seismic response by forward modeling. By constructing two-dimensional numerical models of caves of different scales and morphologies and performing finite element forward modeling, the differences in seismic response caused by morphological and scale changes are compared and analyzed from multiple perspectives such as amplitude, waveform, and frequency, the influence of cave morphological and scale changes on the wave field is clarified, and a certain quantitative understanding is formed, thereby providing effective basic support for the efficient development of carbonate fracture-cave oil reservoirs.

[0121] For other detailed descriptions and advantages of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0122] Example 3

[0123] According to another aspect of the present invention, an electronic device is provided. The electronic device comprises:

[0124] Memory, which stores executable instructions:

[0125] A processor runs the executable instructions in the memory to implement the method of studying the influence of cave changes on seismic response by forward simulation according to the present invention.

[0126] Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc.

[0127] The processor may be a central processing unit (CPU) or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of the present invention, the processor is used to run the computer-readable instructions stored in the memory.

[0128] The method for studying the influence of cave changes on seismic response by forward simulation comprises the following steps:

[0129] Step 1, establishing a two-dimensional stratigraphic framework model, wherein the model includes multiple sets of main stratigraphic layers;

[0130] Step 2, setting a plurality of groups of caves with different scales and shapes in the target layer of the stratigraphic framework model;

[0131] Step 3, conducting finite element numerical simulation on the two-dimensional geological model to obtain simulated single shot data;

[0132] Step 4, performing prestack depth migration processing on the simulated single shot data;

[0133] Step 5: Compare and analyze the seismic response characteristics of the data after migration processing to obtain the relationship between the size and shape of the cave and the seismic response characteristics.

[0134] In some embodiments, the different shapes include square, circle, and irregular shape.

[0135] In some implementations, in step 4, a Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on the simulated single shot data.

[0136] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0137] This embodiment provides a scheme for studying the influence of cave scale and morphological changes on seismic response by using forward simulation. By constructing two-dimensional numerical models of caves of different scales and morphologies and performing finite element forward simulation, the differences in seismic response caused by morphological and scale changes are compared and analyzed from multiple perspectives such as amplitude, waveform, and frequency, the influence of cave morphological and scale changes on the wave field is clarified, and a certain quantitative understanding is formed, thereby providing effective basic support for the efficient development of carbonate fracture-cave oil reservoirs.

[0138] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0139] Example 4

[0140] According to another aspect of the present invention, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the method of using forward simulation to study the influence of cave changes on seismic response according to the present invention is implemented.

[0141] The computer-readable storage medium according to the embodiment of the present invention stores non-transitory computer-readable instructions, and when the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the above-mentioned methods of the embodiments of the present invention are executed.

[0142] The above-mentioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or mobile hard disk), media with built-in rewritable non-volatile memory (e.g., memory card) and media with built-in ROM (e.g., ROM box).

[0143] Those skilled in the art should be able to understand that in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the protection scope of the present invention.

[0144] The method for studying the influence of cave changes on seismic response by forward simulation comprises the following steps:

[0145] Step 1, establishing a two-dimensional stratigraphic framework model, wherein the model includes multiple sets of main stratigraphic layers;

[0146] Step 2, setting a plurality of groups of caves with different scales and shapes in the target layer of the stratigraphic framework model;

[0147] Step 3, conducting finite element numerical simulation on the two-dimensional geological model to obtain simulated single shot data;

[0148] Step 4, performing prestack depth migration processing on the simulated single shot data;

[0149] Step 5: Comparative analysis of seismic response characteristics of the data after migration processing is performed to obtain the relationship between the size and shape of the cave and the seismic response characteristics.

[0150] In some embodiments, the different shapes include square, circle, and irregular shape.

[0151] In some implementations, in step 4, a Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on the simulated single shot data.

[0152] In some embodiments, the seismic response characteristics include imaging profiles, root mean square amplitude of the bead at time t0, waveform and spectrum of the bead center trace, frequency-divided instantaneous amplitude attributes, and time-frequency spectrum.

[0153] This embodiment provides a scheme for studying the influence of cave scale and morphological changes on seismic response by using forward simulation. By constructing two-dimensional numerical models of caves of different scales and morphologies and performing finite element forward simulation, the differences in seismic response caused by morphological and scale changes are compared and analyzed from multiple perspectives such as amplitude, waveform, and frequency, the influence of cave morphological and scale changes on the wave field is clarified, and a certain quantitative understanding is formed, thereby providing effective basic support for the efficient development of carbonate fracture-cave oil reservoirs.

[0154] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0155] Example 5

[0156] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0157] The present invention takes carbonate fracture-cave reservoir as the research object. Firstly, according to the stratigraphic age information of the research area, a two-dimensional geological model is constructed, and four sets of main stratigraphic velocities are designed. From top to bottom, the stratigraphic velocities are 3900m / s, 4950m / s, 4650m / s, and 5300m / s, respectively. The surrounding rock velocity is 6000m / s, and the velocity in the cave is 4500m / s. The observation system is designed with a track spacing of 30m and a shot spacing of 30m. The simulated wavelet is a 25hz Ricker wavelet. Figure 2 A schematic diagram of a two-dimensional stratum framework model established according to this exemplary embodiment is shown.

[0158] Figure 3 A schematic diagram of meshing results of caves of different shapes according to this exemplary embodiment is shown.

[0159] Figure 4The schematic diagram of the prestack depth migration results of caves with different scales and shapes according to this exemplary embodiment is shown, including a 900m 2 Square holes, round holes and irregular holes, with a size of 1600m 2 Square holes, round holes and irregular holes and holes with a size of 2500m 2 Square holes, round holes and irregular holes.

[0160] Figure 5 (a), (b), and (c) show schematic diagrams of the root mean square amplitude of caves with different scales and shapes according to this exemplary embodiment. Figure 5 (a) is 900m in size 2 Schematic diagram of the RMS amplitude of square holes, round holes and irregular holes; Figure 5 (b) is 1600m in size 2 Schematic diagram of the RMS amplitude of square holes, round holes and irregular holes; Figure 5 (c) is 2500m in size 2 Schematic diagram of the RMS amplitude of square holes, round holes and irregular holes.

[0161] Figure 6 (a), (b), and (c) show waveforms and spectrum diagrams of caves with different scales and shapes according to this exemplary embodiment. Figure 6 The upper and lower images in (a) are 900m in size. 2 Waveform diagrams and spectrum diagrams of square holes, round holes and irregular holes; Figure 6 The upper and lower images in (b) are 1600m in size. 2 Waveform diagrams and spectrum diagrams of square holes, round holes and irregular holes; Figure 6 The upper and lower images in (c) are 2500m in size. 2 Waveform diagrams and spectrum diagrams of square holes, round holes and irregular holes.

[0162] according to Figure 4 , Figure 5 (a), (b), (c) and Figure 6 From the seismic response characteristics shown in (a), (b) and (c), at the scale of 2500㎡, there is basically no difference between the characteristics of square caves and round caves, and there is a slight difference in the RMS amplitude and spectrum of irregular caves. As the scale of the cave becomes smaller, the degree of difference becomes smaller; at the scale of 900㎡, there is basically no difference in the imaging profiles, RMS amplitude, waveform and spectrum of the three morphological caves, square caves, round caves and irregular caves.

[0163] Figure 7 FIG. 1 shows a time-frequency spectrum of caves with different scales and morphologies according to this exemplary embodiment. Figure 7It can be seen that as the cave area increases, the main frequency of the cave response tends to decrease, and the decrease in the main frequency of irregular caves is more obvious.

[0164] By comparing and analyzing the seismic response characteristics of caves of different shapes from multiple angles such as amplitude, waveform, and frequency, we can describe the differences between cave responses more comprehensively and deeply, thereby obtaining a more accurate understanding.

[0165] In summary, each embodiment of the present invention provides a technical solution for studying the influence of cave scale and morphological changes on seismic response by forward modeling. By constructing two-dimensional numerical models of caves of different scales and morphologies and performing finite element forward modeling, the differences in seismic response caused by morphological and scale changes are compared and analyzed from multiple perspectives such as amplitude, waveform, and frequency, and the influence of cave morphology and scale changes on the wave field is clarified, forming a certain quantitative understanding, thereby providing effective basic support for the efficient development of carbonate fracture-cave reservoirs. The advantages of this technical solution are analyzed in detail as follows.

[0166] 1. A quantitative cave scale-morphology-seismic response characteristic relationship model was established to achieve the prediction and transplantation of the response of complex carbonate oil and gas reservoirs.

[0167] 2. The introduction of the finite element forward numerical realization algorithm ensures the accuracy and reliability of the simulation results and significantly improves the simulation accuracy.

[0168] 3. Kirchhoff migration processing technology based on ray tracing theory makes the calculation more efficient.

[0169] Fourth, the influence of reservoir cave scale and morphological changes on seismic response is revealed, enriching the theoretical understanding of wave field propagation mechanism.

[0170] 5. Multi-angle analysis methods increase the dimension of feature extraction and provide a reliable basic support for the efficient development of carbonate oil and gas reservoirs.

[0171] 6. The forward simulation and attribute analysis process provides a technical example for the study of deep and complex oil and gas reservoirs and can be widely applied.

[0172] It can be understood that the above embodiments mentioned in the present disclosure can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present disclosure will not repeat them. It can be understood by those skilled in the art that in the above methods of the specific implementation, the specific execution order of each step should be determined according to its function and possible internal logic.

[0173] Note that, unless otherwise directly stated, all features disclosed in this specification (including any attached claims, abstracts and drawings) may be replaced by alternative features for achieving the same, equivalent or similar purposes. Therefore, unless otherwise explicitly stated, each feature disclosed is only an example of a group of equivalent or similar features. Where used, further, preferably, further and more preferably are simple beginnings for elaborating another embodiment based on the aforementioned embodiment, and the content of the further, preferably, further or more preferably followed by the combination with the aforementioned embodiment constitutes a complete construction of another embodiment. Several further, preferably, further or more preferably settings following the same embodiment can be arbitrarily combined to form another embodiment.

[0174] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for studying the impact of cave changes on seismic response using forward modeling. It is characterized in that The following steps are involved: Step 1, establishing a two-dimensional stratigraphic framework model, wherein the model includes multiple sets of main stratigraphic layers; Step 2, setting a plurality of groups of caves with different scales and shapes in the target layer of the stratigraphic framework model; Step 3, conducting finite element numerical simulation on the two-dimensional geological model to obtain simulated single shot data; Step 4, performing prestack depth migration processing on the simulated single shot data; Step 5: Comparative analysis of seismic response characteristics of the data after migration processing is performed to obtain the relationship between the size and shape of the cave and the seismic response characteristics.

2. The method according to claim 1, It is characterized in that The different shapes include square, circular and irregular shapes.

3. The method according to claim 1, It is characterized in that In step 4, the Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on the simulated single-shot data.

4. The method according to claim 1, It is characterized in that The seismic response characteristics include imaging profiles, root mean square amplitude of the beads at time t0, waveform and spectrum of the center channel of the beads, frequency division instantaneous amplitude attributes and time-frequency spectrum.

5. A device for studying the influence of cave changes on seismic response using forward simulation, It is characterized in that include: A model building unit, used for building a two-dimensional stratigraphic framework model, wherein the model includes a plurality of sets of main stratigraphic layers; The karst cave setting unit is used to set multiple groups of karst caves with different scales and shapes in the target layer of the stratigraphic framework model; Finite element numerical simulation unit, used to carry out finite element numerical simulation on two-dimensional geological model and obtain simulated single shot data; A pre-stack depth migration processing unit is used to perform pre-stack depth migration processing on simulated single shot data; The seismic response analysis unit is used to compare and analyze the seismic response characteristics of the data after migration processing, and obtain the relationship between the scale and shape of the cave and the seismic response characteristics.

6. The device according to claim 5, It is characterized in that The different shapes include square, circular and irregular shapes.

7. The device according to claim 5, It is characterized in that In the prestack depth migration processing unit, the Kirchhoff prestack depth migration method is used to perform prestack depth migration processing on the simulated single shot data.

8. The device according to claim 5, It is characterized in that The seismic response characteristics include imaging profiles, root mean square amplitude of the beads at time t0, waveform and spectrum of the center channel of the beads, frequency division instantaneous amplitude attributes and time-frequency spectrum.

9. An electronic device, It is characterized in that The electronic device comprises: A memory storing executable instructions; A processor, wherein the processor runs the executable instructions in the memory to implement the method according to any one of claims 1 to 4.

10. A computer-readable storage medium storing a computer program, wherein the computer program implements the method according to any one of claims 1 to 4 when executed by a processor.

Images