TOC content earthquake prediction method and system based on pre-stack rock physical quantity plate

Abstract

The invention discloses a TOC content earthquake prediction method and system based on a pre-stack rock physical quantity plate, and belongs to the technical field of earthquake prediction. Pre-stack rock physical elastic parameters sensitive to the shale TOC content are analyzed, and then a pre-stack rock physical quantity plate of the shale TOC content is established according to the analysis result of the pre-stack rock physical elastic parameters; according to the method, the pre-stack inversion is carried out according to the pre-stack rock physical quantity plate of the TOC content of the shale, and then the plane distribution of the TOC content of the shale is predicted, the method solves the problem that when the TOC content in the shale is predicted through the post-stack wave impedance or the post-stack seismic attribute, multiple solutions exist, and the plane distribution characteristics of the TOC content in the shale can be effectively predicted. Moreover, the prediction method provided by the invention has a good application effect in practical application, a good production actual effect is achieved, and the distribution of the TOC content of the marine facies shale predicted by the method is highly matched with the distribution of the TOC content of the marine facies shale on the ground at present.

Description

Technical Field

[0001] The present invention belongs to the technical field of earthquake prediction, and in particular relates to a TOC content earthquake prediction method and system based on pre-stack rock physical quantity version. Background Art

[0002] TOC (Total Organic Carbon) content is one of the important parameters for evaluating the sweet spots of shale gas reservoirs, and it is crucial to quantitatively characterize its geophysical parameters. In the existing technology, TOC content is generally obtained by experimental analysis of core, outcrop or cuttings samples. However, the experimental analysis obtains discrete TOC content data. In areas without wells or with less coring, it is difficult to carry out sweet spot evaluation of shale gas TOC content. Seismic data plays an important role in shale gas exploration and development due to its high lateral and vertical resolution. Previous predictions of TOC content were mostly based on post-stack seismic attributes, wave impedance, pre-stack inversion density bodies, frequency division inversion, etc. These methods often have certain multi-solutions, and the prediction accuracy is difficult to guarantee. The first method is to obtain the TOC content value of the rock sample by laboratory measurement, and then compare and analyze it with the well logging curve of the corresponding depth to qualitatively determine the well logging response characteristics corresponding to the TOC content. This is to achieve the purpose of predicting TOC content by well logging response characteristics. The relationship between seismic attributes and well logging responses is further exploited to determine the seismic attribute characteristics corresponding to the well logging responses, thereby indirectly predicting TOC content from seismic attributes. However, the disadvantage of this approach is that the TOC content curves obtained by statistically fitting the well logging curves have large errors, and the method for establishing the relationship with seismic attributes is overly simplistic, resulting in large errors. A second approach is to directly predict the spatial distribution of TOC content using seismic data in conjunction with geological analysis. This approach has very low vertical accuracy and even greater errors in the prediction results. Currently, no effective solution has been proposed to improve the accuracy of TOC content prediction. Summary of the Invention

[0003] In response to the above problems, in a first aspect, the present invention proposes a TOC content seismic prediction method based on prestack rock physics, comprising the following steps:

[0004] Analyze pre-stack rock physical elastic parameters that are sensitive to shale TOC content;

[0005] Based on the analysis results of pre-stack rock physical elastic parameters, a pre-stack rock physical quantity version of shale TOC content is established;

[0006] Prestack inversion is performed based on the prestack rock physical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content.

[0007] Furthermore, the analysis of pre-stack rock physical elastic parameters sensitive to shale TOC content includes the following steps:

[0008] Conduct experimental analysis and testing on key pre-stack rock physical elastic parameters and TOC content of shale cores;

[0009] Determine the pre-stack rock physical sensitive elastic parameters of shale TOC content based on the test results;

[0010] The pre-stack rock physical sensitive elastic parameters are analyzed.

[0011] Furthermore, before conducting experimental analysis of key pre-stack rock physical elastic parameters and TOC content of shale cores, the following tests are also conducted:

[0012] The cores of typical shale development sections in the study area were observed, and samples were collected from the shale cores.

[0013] Furthermore, the establishment of a pre-stack petrophysical plate of shale TOC content includes the following steps:

[0014] The TOC content of shale is analyzed in conjunction with the pre-stack rock physical sensitive elastic parameters;

[0015] The pre-stack rock physics version of shale TOC content is established based on the results of intersection analysis.

[0016] Furthermore, performing prestack inversion based on the prestack petrophysical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content includes the following steps:

[0017] Perform prestack inversion on the prestack rock physical sensitive elastic parameters until the prestack rock physical sensitive elastic parameters obtained by prestack inversion are consistent with the prestack rock physical sensitive elastic parameters measured by well logging;

[0018] Predicting the TOC content of the shale based on prestack seismic data according to the prestack rock physics version of the TOC content of the shale;

[0019] The shale TOC content predicted based on pre-stack seismic data was processed using the formation slicing technology to obtain the planar distribution of the shale TOC content in the target layer.

[0020] Furthermore, the key pre-stack rock physics elastic parameters include Poisson's ratio, longitudinal wave velocity, shear wave velocity, and longitudinal wave velocity / shear wave velocity.

[0021] Furthermore, the pre-stack rock physical sensitive elastic parameters are Poisson's ratio and P-wave velocity / S-wave velocity.

[0022] In a second aspect, the present invention proposes a TOC content seismic prediction system based on pre-stack rock physics, comprising:

[0023] Elastic parameter analysis unit, used to analyze pre-stack rock physical elastic parameters that are sensitive to shale TOC content;

[0024] A quantitative plate establishing unit is used to establish a pre-stack rock physical quantitative plate of shale TOC content based on the analysis results of pre-stack rock physical elastic parameters;

[0025] The TOC content prediction unit is used to perform pre-stack inversion based on the pre-stack rock physical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content.

[0026] In a third aspect, the present invention provides an electronic device comprising a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0027] a memory storing a computer program;

[0028] The processor is used to implement the TOC content seismic prediction method based on pre-stack rock physical quantity version when executing the program stored in the memory.

[0029] In a fourth aspect, the present invention proposes a computer-readable storage medium storing a computer program, which, when executed, executes the TOC content seismic prediction method based on pre-stack rock physics.

[0030] Beneficial effects of the present invention:

[0031] The present invention first analyzes the pre-stack rock physical elastic parameters that are sensitive to the TOC content of shale, and then establishes a pre-stack rock physical quantity version of the shale TOC content based on the analysis results of the pre-stack rock physical elastic parameters. Pre-stack inversion is performed based on the pre-stack rock physical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content, thereby solving the problem of multiple solutions when using post-stack wave impedance or post-stack seismic attributes to predict the TOC content in shale. The breakthrough organic combination of pre-stack elastic parameter experiments of core samples and pre-stack seismic data can effectively predict the planar distribution characteristics of the TOC content in shale. In addition, the prediction method proposed by the present invention has achieved good application results in practical applications and has achieved good production results. The distribution of TOC content in marine shale currently predicted by this method is highly consistent with that on the well.

[0032] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 The flowchart of the TOC content seismic prediction method based on pre-stack rock physics is shown in the present invention;

[0035] Figure 2 A scatter plot of prestack elastic parameters of Poisson's ratio, longitudinal wave impedance and TOC content based on shale core samples in the study area proposed in an embodiment of the present invention is shown;

[0036] Figure 3 The figure shows the pre-stack rock physics plate established based on the P-wave velocity / S-wave velocity (Vp / Vs) and TOC content in the study area in the embodiment of the present invention;

[0037] Figure 4 The figure shows the pre-stack seismic inversion profile of the P-wave velocity / S-wave velocity (Vp / Vs) of the study area through Well A in the embodiment of the present invention (the curve in the figure is a mirror image of the Vp / Vs measured based on well logging);

[0038] Figure 5 The figure shows the pre-stack seismic inversion profile of shale TOC content passing through Well A in the study area in the embodiment of the present invention;

[0039] Figure 6 The plane contour map of TOC content of shale in the target layer of the study area in the embodiment of the present invention is shown;

[0040] Figure 7 The figure shows the schematic diagram of the TOC content seismic prediction system based on the pre-stack rock physics version in an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of the architecture of an electronic device proposed in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] To address the challenges of existing technologies, this paper proposes a seismic prediction method for TOC content based on a prestack rock physics plate. By analyzing the prestack rock physics elastic parameters of core samples, a rock physics plate based on prestack elastic parameters is established. Prestack inversion is then performed to predict the planar distribution of TOC content in shale. This method complements the use of post-stack seismic data for TOC content prediction and further expands the range of methods for predicting shale TOC content using seismic data. Furthermore, this method provides a new technical means for predicting the distribution of TOC sweet spots in shale.

[0044] like Figure 1 As shown, the prediction method includes the following steps:

[0045] S1: Analysis of pre-stack rock physical elastic parameters sensitive to shale TOC content;

[0046] The analysis of pre-stack rock physical elastic parameters sensitive to shale TOC content includes the following steps:

[0047] Observe the cores of typical shale development sections in the study area and collect samples from shale cores;

[0048] Conduct experimental analysis and testing on key pre-stack rock physics elastic parameters and TOC content of shale cores to obtain TOC content data of shale;

[0049] Based on the test results, pre-stack rock physical elastic parameters that are sensitive to the TOC content of shale, namely, pre-stack rock physical sensitive elastic parameters, are determined; the key pre-stack rock physical elastic parameters include Poisson's ratio (б), longitudinal wave impedance, longitudinal wave velocity (Vp), shear wave velocity (Vs), longitudinal wave velocity / shear wave velocity analysis, longitudinal wave impedance, and shear wave impedance; the pre-stack rock physical sensitive elastic parameters are Poisson's ratio and longitudinal wave velocity / shear wave velocity.

[0050] The pre-stack rock physical sensitive elastic parameters are analyzed, and the results are as follows: Figure 2 Figure 2 shows a scatter plot of prestack elastic parameters, including Poisson's ratio, P-wave impedance, and TOC content, derived from shale core samples from the study area. It can be seen that siliceous shales with high TOC content often exhibit low Poisson's ratios and moderate P-wave impedance (the product of Vp and density ρ). However, calcium-rich shales with low TOC content exhibit high Poisson's ratios and high P-wave impedance.

[0051] S2: Establish a pre-stack rock physics plate for shale TOC content based on the analysis results of pre-stack rock physics elastic parameters;

[0052] Specifically, the TOC content of shale is analyzed with pre-stack rock physical sensitive elastic parameters, such as Poisson's ratio, P-wave velocity, S-wave velocity, and P-wave velocity / S-wave velocity (Vp / Vs);

[0053] The pre-stack rock physics version of shale TOC content is established based on the results of intersection analysis.

[0054] In one embodiment of the present invention, there is a good statistical relationship between Poisson's ratio, P-wave velocity / S-wave velocity and shale TOC content, thereby establishing a pre-stack rock physics version of shale TOC content; Figure 3 As shown in the figure, based on the pre-stack rock physics plate established based on Vp / Vs and TOC content, the quantitative relationship between TOC content and Vp / Vs of shale in the study area is determined:

[0055] TOC=exp(78.81-86.12*Vp / Vs+22.08*Vp / Vs*Vp / Vs)

[0056] Correlation R between TOC and Vp / Vs 2 The Poisson's ratio is positively correlated with the P-wave velocity / S-wave velocity, indicating that the characteristics of the pre-stack rock physics sensitive elastic parameters of the TOC content of shale in the study area are still applicable.

[0057] S3: performing prestack inversion based on the prestack rock physics version of the shale TOC content to predict the planar distribution of the shale TOC content. In one embodiment of the present invention, the specific steps are as follows:

[0058] By performing pre-stack inversion on the P-wave velocity / S-wave velocity, which are sensitive elastic parameters of pre-stack rock physics, the key parameters of pre-stack inversion are repeatedly adjusted until the P-wave velocity / S-wave velocity obtained from pre-stack inversion is consistent with the P-wave velocity / S-wave velocity obtained from well logging.

[0059] The TOC content of shale is predicted based on the established pre-stack rock physics version of shale TOC content, that is, the TOC content is obtained by converting the quantitative relationship between TOC content and Vp / Vs in the pre-stack rock physics version of shale TOC content;

[0060] The planar distribution range of the TOC content of the target shale can be obtained using the formation slicing technique. Formation slicing is a function built into some geophysical software. After obtaining the TOC content of the TOC seismic data volume obtained by inversion based on prestack seismic data in the study area, the formation slicing technique is used to determine the planar distribution range of the TOC content of the target shale after setting the top interface, bottom interface, and number of slices in the software.

[0061] In one embodiment of the present invention, the Vp / Vs obtained by pre-stack inversion is calculated until the agreement between the Vp / Vs obtained by well logging reaches 0.7 or above. Figure 4 is the pre-stack seismic inversion profile of Vp / Vs through Well A in the study area (the curve in the figure is a mirror image of Vp / Vs based on well logging). Figure 4 It can be seen that the prestack inversion based on Vp / Vs is in excellent agreement with the Vp / Vs measured by well logging. Based on the quantitative relationship between TOC content and Vp / Vs in the shale of the study area in Step 2, the prestack seismic inversion profile of Vp / Vs passing through Well A can be converted into a prestack inversion profile of TOC content. Figure 5 The TOC content of the shale in the study area is converted into a prestack seismic inversion profile through Well A, based on the quantitative relationship between TOC content and Vp / Vs. Finally, using stratigraphic slicing technology, a contour map of TOC content in the target shale interval in the study area is obtained. Figure 6 This is the plane contour map of shale TOC content in the target layer of the study area.

[0062] The prediction method proposed in the present invention has achieved good application results and played a very good production effect. The distribution of TOC content in marine shale predicted by this technology is currently consistent with that on the well.

[0063] Based on the same concept of the present invention, another exemplary embodiment of the present invention provides a TOC content seismic prediction system based on pre-stack rock physics, such as Figure 7 Shown, including:

[0064] Elastic parameter analysis unit 701, used to analyze pre-stack rock physical elastic parameters that are sensitive to shale TOC content;

[0065] A quantity plate establishing unit 702 is used to establish a pre-stack rock physical quantity plate of shale TOC content based on the analysis results of pre-stack rock physical elastic parameters;

[0066] The TOC content prediction unit 703 is configured to perform pre-stack inversion based on the pre-stack petrophysical version of the shale TOC content to predict the planar distribution of the shale TOC content.

[0067] Based on the same inventive concept, another exemplary embodiment of the present invention provides an electronic device. Figure 8 As shown, the electronic device includes at least one processor 801, at least one communication interface 802, at least one memory 803 and at least one communication bus 804; wherein the processor 801, the communication interface 802 and the memory 803 communicate with each other via the communication bus 804;

[0068] Memory 803, storing computer programs;

[0069] The processor 801 is configured to implement the TOC content seismic prediction method based on pre-stack rock physics when executing the program stored in the memory 803.

[0070] Optionally, the communication interface may be an interface of a communication module, such as an interface of a GSM module; the processor may be a CPU, or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention. The memory may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk storage. The memory stores a program, and the processor calls the program stored in the memory to execute some or all of the above-mentioned method embodiments.

[0071] Based on the same inventive concept, an embodiment of the present application further provides a computer-readable storage medium storing a computer program, wherein when the computer program is executed, some or all of the above-mentioned method embodiments are implemented. Optionally, the storage medium may be a non-transitory computer-readable storage medium, for example, a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0072] Although the present invention 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 make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A TOC content seismic prediction method based on pre-stack rock physics, characterized in that: The following steps are involved: Analyze pre-stack rock physical elastic parameters that are sensitive to shale TOC content; Based on the analysis results of pre-stack rock physical elastic parameters, a pre-stack rock physical quantity version of shale TOC content is established; Prestack inversion is performed based on the prestack rock physical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content.

2. The TOC content seismic prediction method based on prestack rock physics according to claim 1 is characterized in that: The analysis of pre-stack rock physical elastic parameters sensitive to shale TOC content includes the following steps: Conduct experimental analysis and testing on key pre-stack rock physical elastic parameters and TOC content of shale cores; Determine the pre-stack rock physical sensitive elastic parameters of shale TOC content based on the test results; The pre-stack rock physical sensitive elastic parameters are analyzed.

3. The TOC content seismic prediction method based on prestack rock physics according to claim 2 is characterized in that: Before the experimental analysis of key elastic parameters and TOC content of pre-stack rock physics of shale cores, the following tests were also conducted: The cores of typical shale development sections in the study area were observed, and samples were collected from the shale cores.

4. The TOC content seismic prediction method based on prestack rock physics according to claim 2 is characterized in that: The method of establishing a pre-stack rock physics version of shale TOC content includes the following steps: The TOC content of shale is analyzed in conjunction with the pre-stack rock physical sensitive elastic parameters; The pre-stack rock physics version of shale TOC content is established based on the results of intersection analysis.

5. The TOC content seismic prediction method based on prestack rock physics according to claim 2 is characterized in that: Pre-stack inversion is performed based on the pre-stack rock physics version of the shale TOC content to predict the planar distribution of the shale TOC content, including the following steps: Perform prestack inversion on the prestack rock physical sensitive elastic parameters until the prestack rock physical sensitive elastic parameters obtained by prestack inversion are consistent with the prestack rock physical sensitive elastic parameters measured by well logging; Predicting the TOC content of the shale based on prestack seismic data according to the prestack rock physics version of the TOC content of the shale; The shale TOC content predicted based on pre-stack seismic data was processed using the formation slicing technology to obtain the planar distribution of the shale TOC content in the target layer.

6. The TOC content seismic prediction method based on prestack rock physics according to any one of claims 2 to 5, characterized in that: The key pre-stack rock physics elastic parameters include Poisson's ratio, P-wave velocity, S-wave velocity, and P-wave velocity / S-wave velocity.

7. The TOC content seismic prediction method based on prestack rock physics according to any one of claims 2 to 5, characterized in that: The pre-stack rock physical sensitive elastic parameters are Poisson's ratio and P-wave velocity / S-wave velocity.

8. A TOC content seismic prediction system based on pre-stack rock physics, characterized by: include: Elastic parameter analysis unit, used to analyze pre-stack rock physical elastic parameters that are sensitive to shale TOC content; A quantitative plate establishing unit is used to establish a pre-stack rock physical quantitative plate of shale TOC content based on the analysis results of pre-stack rock physical elastic parameters; The TOC content prediction unit is used to perform pre-stack inversion based on the pre-stack rock physical quantity version of the shale TOC content to predict the planar distribution of the shale TOC content.

9. An electronic device, characterized in that: The processor, the communication interface, the memory and the communication bus are connected to each other via the communication bus. a memory storing a computer program; The processor is configured to implement the TOC content seismic prediction method based on prestack rock physics version according to any one of claims 1 to 7 when executing the program stored in the memory.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, the TOC content seismic prediction method based on pre-stack rock physical quantity version according to any one of claims 1 to 7 is executed.

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