Limit resolution-based stratigraphic pinch-out point identification method and device, and medium

Abstract

The present application relates to a kind of stratum pinch-out point identification method, device and medium based on limit resolution, method includes the following steps: establishing the geological model of sandstone formation in purpose layer section;Stratum pinch-out point position is identified by seismic profile to the seismic data of geological model, estimation sandstone formation top and bottom angle θ And sandstone top angle α;Based on seismic profile, the main frequency f of seismic data in sandstone formation time window is obtained;Based on the data including well logging or inversion, the propagation velocity v of seismic wave in sandstone formation is obtained;Based on the angle θ of sandstone formation top and bottom, sandstone top angle α, the main frequency f of seismic data in sandstone time window and the propagation velocity v of seismic wave in sandstone formation, the error Δx between stratum pinch-out point position and actual position is calculated;The distance of the error calculated based on the stratum pinch-out point position identified along the direction of stratum top surface upward inclination is extended, the position of actual pinch-out point is obtained.

Description

Technical Field

[0001] This invention relates to a method, apparatus, and medium for identifying formation pinch-out points based on extreme resolution, belonging to the field of oil and gas exploration technology. Background Technology

[0002] In recent years, with the deepening of oil and gas field exploration and development, the exploration situation has become increasingly complex. In lithological and stratigraphic oil and gas reservoirs, characterizing the pinch-out points of sandstone strata is crucial for lithological oil and gas reservoir evaluation and remains a challenging area of ​​research both domestically and internationally. Limited by the resolution of seismic data, there is usually an error between the location of the pinch-out point on the seismic profile and the actual location of the pinch-out point in the strata. This error is related not only to the dominant frequency and propagation velocity of the seismic data but also to the dip angle of the strata and the angle between the top and bottom surfaces of the sandstone. To improve the accuracy of pinch-out point identification, several processing methods are currently used: firstly, high-resolution processing is used to improve the accuracy of stratigraphic pinch-out point identification; secondly, attribute analysis methods are used to identify stratigraphic pinch-out points, including phase and coherence attributes; and finally, forward modeling is used to infer the location of stratigraphic pinch-out points. However, the first two methods are limited by the resolution of seismic data, and the identified locations still have errors. Forward modeling is not universally applicable and suffers from multiple solutions. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method, apparatus, and medium for identifying formation pinch-out points based on ultimate resolution. This method calculates the error between the identified pinch-out point location and the actual location by using the dominant frequency of the seismic signal, the propagation velocity of the seismic wave, the angle between the top and bottom surfaces of the formation, and the dip angle of the top surface. This allows for accurate identification of formation pinch-out point locations and improves the accuracy of oil and gas reservoir evaluation.

[0004] like Figure 1 As shown, based on the Wides criterion (see: Wides M. How thin is a thin bed? [J]. Geophysics, 1973, 38(6): 1176–1180. DOI: 10.1190 / 1.1440403), the thinnest stratum that a seismic wavelet can identify is one-quarter of the seismic wavelength, which is the limiting resolution. Assuming the dominant frequency of the seismic signal is f, the stratum thickness that the limiting resolution can identify can be expressed as:

[0005]

[0006] That is, the pinch-out point location shown on the seismic profile is the stratum thickness at point A; when the angle between the top and bottom surfaces of the sandstone stratum is θ and the dip angle of the top surface of the sandstone is α, then the error between the calculated limiting resolution location A and the actual pinch-out point B, i.e., the distance between A and B, can be expressed as:

[0007]

[0008] Based on the above principles, the present invention adopts the following technical solution:

[0009] A method for identifying formation pinch-out points based on extreme resolution includes the following steps:

[0010] Establish a geological model of the sandstone strata in the target section;

[0011] Interpret seismic data from geological models and identify stratigraphic pinch-out points using seismic profiles;

[0012] Based on the seismic profile, the geometric properties of the sandstone strata in the target section are obtained. Based on the geometric properties of the sandstone strata at the pinch-out point of the target section, the included angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone are estimated.

[0013] The dominant frequency f of seismic data within a time window of sandstone strata is obtained based on seismic profiles;

[0014] The propagation velocity v of seismic waves in sandstone formations is obtained based on data including well logging or inversion.

[0015] Based on the angle θ between the top and bottom surfaces of the sandstone strata, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone strata, the error Δx between the location of the pinch-out point of the strata and its actual location is calculated.

[0016] The actual location of the pinch-out point is obtained by extending the identified pinch-out point location along the top surface of the formation in the upward dip direction and calculating the error distance.

[0017] The formation pinch-out point identification method based on limit resolution preferably uses the following formula to calculate the error Δx between the formation pinch-out point location and the actual location:

[0018]

[0019] The aforementioned stratigraphic pinch-out point identification method, preferably, involves interpreting seismic data of sandstone strata in the target stratigraphic segment and identifying the location of stratigraphic pinch-out points through seismic profiles, as detailed below:

[0020] Based on the principle of envelope interpretation, seismic data of sandstone strata in the target section are interpreted to identify the location of stratigraphic pinch-out points.

[0021] The stratigraphic pinch-out point identification method based on extreme resolution preferably uses the angle θ between the top and bottom surfaces of the sandstone stratum as the average angle between the tangents of the top and bottom surfaces of the bottom segment of the sandstone stratum pinch-out point, and the dip angle α of the top surface of the sandstone as the average angle between the tangent of the top surface of the sandstone stratum pinch-out point segment and the horizontal line.

[0022] The aforementioned stratigraphic pinch-out point identification method, preferably, involves performing a Fourier transform on the target layer of the seismic profile to obtain the dominant frequency f of the seismic data within the time window of the sandstone strata. The specific process is as follows:

[0023] The amplitude spectrum of the seismic data of the target layer is obtained by Fourier transform, and then the dominant frequency f of the seismic data of the sandstone strata in the target layer is obtained within the time window.

[0024] A second aspect of the present invention provides a formation pinch-out point identification device based on extreme resolution, comprising:

[0025] The first processing unit is used to establish a geological model of the sandstone strata in the target section.

[0026] The second processing unit is used to interpret the seismic data of the geological model and identify the location of stratigraphic pinch-out points through seismic profiles.

[0027] The third processing unit is used to obtain the geometric properties of the sandstone strata in the target section based on the seismic profile, and to estimate the included angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone strata based on the geometric properties of the sandstone strata at the pinch-out point of the target section.

[0028] The fourth processing unit is used to obtain the dominant frequency f of seismic data within a time window of sandstone strata based on seismic profiles;

[0029] The fifth processing unit is used to obtain the propagation velocity v of seismic waves in sandstone formations based on data including well logging or inversion.

[0030] The sixth processing unit is used to calculate the error Δx between the pinch-out point location and the actual location of the formation based on the included angle θ between the top and bottom surfaces of the sandstone formation, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone formation.

[0031] The seventh processing unit is used to obtain the actual location of the pinch-out point by extending the calculated error distance along the top surface of the formation in the upward dip direction based on the identified pinch-out point location.

[0032] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described method for identifying stratigraphic pinch-out points based on extreme resolution.

[0033] A fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for identifying stratigraphic pinch-out points based on extreme resolution.

[0034] The present invention has the following advantages due to the adoption of the above technical solutions:

[0035] 1. This invention calculates the error between the identified pinch-out point location and the actual location by using the dominant frequency of the seismic signal, the propagation velocity of the seismic wave, the angle between the top and bottom surfaces of the formation, and the dip angle of the top surface. This allows for the accurate identification of the pinch-out point location and improves the accuracy of oil and gas reservoir evaluation.

[0036] 2. This invention calculates the error based on stratigraphic information and seismic data, thereby obtaining the actual location of stratigraphic pinch-out points, breaking through the limitations of seismic data resolution, and achieving accurate identification of stratigraphic pinch-out point locations. Attached Figure Description

[0037] Figure 1 This is a schematic diagram showing that the thinnest stratum that a seismic wavelet can identify based on the Wides criterion is one-quarter of the seismic wavelength.

[0038] Figure 2 This is a flowchart of a formation pinch-out point identification method based on extreme resolution provided by an embodiment of the present invention;

[0039] Figure 3 This embodiment of the invention provides a diagram showing the relationship between the theoretical error of the identified location of the stratum pinch-out point and its actual location and the angle between the top and bottom surfaces of the stratum when the dip angle of the top surface of the stratum is 0, the seismic wave propagation speed is 3.8 km / s, and the main frequency of the seismic signal is 25 Hz.

[0040] Figure 4 This is the geological model designed for testing in this embodiment of the invention;

[0041] Figure 5 This is a seismic profile synthesized from a geological model during testing in this embodiment of the invention;

[0042] Figure 6 This is an interpretation of the pinch-out point location and the top and bottom surfaces of sandstone identified in the synthetic seismic data tested in this embodiment of the invention. The identified pinch-out point location has an error compared to the actual location.

[0043] Figure 7 This is an interpretation of the pinch-out point location and the top and bottom surfaces of sandstone identified by the method of the present invention in this embodiment of the test. According to the geological model, the seismic wave propagation velocity in sandstone is 3.8 km / s, the stratum angle is 25°, the top surface dip angle is 0, and the calculated error is 81m. Extending the dip direction by 81m can obtain the actual pinch-out point location. The identified pinch-out point location is consistent with the actual location.

[0044] Figure 8 This embodiment of the invention describes the seismic profile and interpretation of the top and bottom surfaces and pinch-out point of the A sand body in the target layer area of ​​the Yinggehai Basin in the western shallow waters of a certain sea area, specifically the Yingdong Slope.

[0045] Figure 9This is the amplitude spectrum of the target seismic segment in this embodiment of the invention;

[0046] Figure 10 This refers to the location of the top and bottom surfaces and pinch-out point of sand body A, as explained by the method proposed in this embodiment of the invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] Currently, several processing methods are used to improve the accuracy of stratigraphic pinch-out point identification. First, high-resolution processing enhances the accuracy. Second, attribute analysis methods, including phase and coherence attributes, are used to identify stratigraphic pinch-out points. Finally, forward modeling is used to infer the location of stratigraphic pinch-out points. However, the first two methods are limited by the resolution of seismic data, resulting in errors in the identified locations. Forward modeling lacks universal applicability and suffers from multiple solutions. To address this issue, this invention provides a stratigraphic pinch-out point identification method based on extreme resolution. This method calculates the error based on stratigraphic and seismic data information, yielding the actual location of stratigraphic pinch-out points. This overcomes the limitations of seismic data resolution and achieves accurate identification of stratigraphic pinch-out point locations.

[0049] like Figure 2 As shown, the stratigraphic pinch-out point identification method based on ultimate resolution described in this invention includes the following steps:

[0050] Establish a geological model of the sandstone strata in the target section;

[0051] Interpret seismic data from geological models and identify stratigraphic pinch-out points using seismic profiles;

[0052] Based on the seismic profile, the geometric properties of the sandstone strata in the target section are obtained. Based on the geometric properties of the sandstone strata at the pinch-out point of the target section, the included angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone are estimated.

[0053] The dominant frequency f of seismic data within a time window of sandstone strata is obtained based on seismic profiles;

[0054] The propagation velocity v of seismic waves in sandstone formations is obtained based on data including well logging or inversion.

[0055] Based on the angle θ between the top and bottom surfaces of the sandstone strata, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone strata, the error Δx between the location of the pinch-out point of the strata and its actual location is calculated.

[0056] The actual location of the pinch-out point is obtained by extending the identified pinch-out point location along the top surface of the formation in the upward dip direction and calculating the error distance.

[0057] The following section uses the interpretation of the target layer A sand body on the Yingdong Slope in the northern part of the Yinggehai Basin in the western shallow waters of a certain sea area as an example to illustrate the entire identification process in detail.

[0058] The northern part of the Yinggehai Basin contains large Oligocene coal-bearing deltaic source rocks, possessing significant exploration potential. The eastern slope zone, adjacent to the Oligocene hydrocarbon generation center, exhibits relatively favorable reservoir properties, favorable accumulation conditions due to tectonic ridges, and developed overburden traps, making it a promising exploration area. For overburden traps, identifying pinch-out points is crucial for reservoir evaluation. The above-mentioned scheme was used to identify overburden pinch-out points on the eastern slope of the Yinggehai Basin. The specific process is as follows:

[0059] Step 1: Seismic Data Interpretation

[0060] The top and bottom surfaces of sand body A are interpreted using the principle of envelope interpretation, and the locations of pinch-out points are identified, yielding interpretation results. For example... Figure 8 As shown, the top and bottom surfaces of the target sand body are clear, and the pinch-out point of the sand body is well-defined. The target can be interpreted based on geological knowledge. In the figure, the white solid line represents the top surface of the sandstone, the black dashed line represents the bottom surface of the sandstone, and the intersection of the top and bottom surfaces in the updip direction is the location of the identified pinch-out point.

[0061] Step 2: Calculate the geometric properties of sandstone

[0062] Based on the seismic profile, the geometric properties of the sandstone strata in the target section are obtained. By using the geometric properties of the sandstone strata at the pinch-out point of the target section, the angle between the top and bottom surfaces of the sandstone strata, i.e., the average angle θ between the tangents of the top and bottom surfaces of the bottom section of the sandstone strata at the pinch-out point, and the dip angle of the top surface of the sandstone, i.e., the average angle α between the tangent of the top surface of the sandstone strata at the pinch-out point and the horizontal line, are estimated. The estimated angle θ between the top and bottom surfaces of the sandstone strata in this target section is 40°, and the dip angle α is 13°.

[0063] Step 3: Obtain the dominant frequency of seismic data for the target section

[0064] The amplitude spectrum of the seismic data for the target section is obtained through Fourier transform, such as... Figure 9 As shown, the dominant frequency f of the seismic data obtained for the target section is 16Hz.

[0065] Step 4: Obtain the seismic wave propagation velocity within the sandstone

[0066] By using data from well logging and inversion, the propagation velocity of seismic waves within the sandstone strata was obtained. In this example, the propagation velocity v of seismic waves in the sandstone strata was 4400 m / s.

[0067] Step 5: Calculate the extinction point identification error Δx

[0068] Based on the following formula:

[0069]

[0070] The calculated error Δx between the identified extinction point and the actual extinction point location is 293m.

[0071] Step 6: Revise the interpretation based on the calculation errors and the results of the preliminary interpretation.

[0072] Based on the error distance calculated by extending the pinch-out point location along the updip direction of the strata from the location of the pinch-out point in the first interpretation, the actual pinch-out point location is obtained, and the interpretation results are corrected.

[0073] A second aspect of the present invention provides a formation pinch-out point identification device based on extreme resolution, comprising:

[0074] The first processing unit is used to establish a geological model of the sandstone strata in the target section.

[0075] The second processing unit is used to interpret the seismic data of the geological model and identify the location of stratigraphic pinch-out points through seismic profiles.

[0076] The third processing unit is used to obtain the geometric properties of the sandstone strata in the target section based on the seismic profile, and to estimate the included angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone strata based on the geometric properties of the sandstone strata at the pinch-out point of the target section.

[0077] The fourth processing unit is used to obtain the dominant frequency f of seismic data within a time window of sandstone strata based on seismic profiles;

[0078] The fifth processing unit is used to obtain the propagation velocity v of seismic waves in sandstone formations based on data including well logging or inversion.

[0079] The sixth processing unit is used to calculate the error Δx between the pinch-out point location and the actual location of the formation based on the included angle θ between the top and bottom surfaces of the sandstone formation, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone formation.

[0080] The seventh processing unit is used to obtain the actual location of the pinch-out point by extending the calculated error distance along the top surface of the formation in the upward dip direction based on the identified pinch-out point location.

[0081] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described method for identifying stratigraphic pinch-out points based on extreme resolution.

[0082] A fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for identifying stratigraphic pinch-out points based on extreme resolution.

[0083] This invention is described based on flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to specific embodiments. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the flowcharts and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0084] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0085] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions 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 method for identifying stratigraphic pinch-out points based on ultimate resolution, characterized in that, Includes the following steps: Establish a geological model of the sandstone strata in the target section; Interpret seismic data from geological models and identify stratigraphic pinch-out points using seismic profiles; Based on the seismic profile, the geometric properties of the sandstone strata in the target section are obtained. Based on the geometric properties of the sandstone strata at the pinch-out point of the target section, the included angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone are estimated. The dominant frequency f of seismic data within a time window of sandstone strata is obtained based on seismic profiles; The propagation velocity v of seismic waves in sandstone formations is obtained based on data including well logging or inversion. Based on the angle θ between the top and bottom surfaces of the sandstone strata, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone strata, the error Δx between the location of the pinch-out point of the strata and its actual location is calculated. The actual location of the pinch-out point is obtained by extending the identified pinch-out point location along the top surface of the formation in the upward dip direction and calculating the error distance.

2. The method for identifying stratigraphic pinch-out points based on ultimate resolution according to claim 1, characterized in that, The formula for calculating the error Δx between the location of the formation pinch-out point and its actual location is as follows:

3. The method for identifying stratigraphic pinch-out points based on ultimate resolution according to claim 1, characterized in that, The seismic data from the geological model are interpreted, and the locations of stratigraphic pinch-out points are identified through seismic profiles, as detailed below: Based on the principle of envelope interpretation, seismic data of sandstone strata in the target section are interpreted to identify the location of stratigraphic pinch-out points.

4. The method for identifying stratigraphic pinch-out points based on ultimate resolution according to claim 1, characterized in that, The angle θ between the top and bottom surfaces of the sandstone strata is the average angle between the tangents of the top and bottom surfaces of the bottom segment of the sandstone strata pinch-out point. The dip angle α of the top surface of the sandstone is the average angle between the tangent of the top surface of the sandstone strata pinch-out point segment and the horizontal line.

5. The method for identifying stratigraphic pinch-out points based on ultimate resolution according to claim 1, characterized in that, The Fourier transform of the target section of the seismic profile is used to obtain the dominant frequency f of the seismic data within the time window of the sandstone strata. The specific process is as follows: The amplitude spectrum of the seismic data of the target layer is obtained by Fourier transform, and then the dominant frequency f of the seismic data of the sandstone strata in the target layer is obtained within the time window.

6. A formation pinch-out point identification device based on extreme resolution, characterized in that, include: The first processing unit is used to establish a geological model of the sandstone strata in the target section. The second processing unit is used to interpret the seismic data of the geological model and identify the location of stratigraphic pinch-out points through seismic profiles. The third processing unit is used to obtain the geometric properties of the sandstone strata in the target section based on the seismic profile, and to estimate the angle θ between the top and bottom surfaces of the sandstone strata and the dip angle α of the top surface of the sandstone strata based on the geometric properties of the sandstone strata at the pinch-out point of the target section. The fourth processing unit is used to obtain the dominant frequency f of seismic data within a time window of sandstone strata based on seismic profiles; The fifth processing unit is used to obtain the propagation velocity v of seismic waves in sandstone formations based on data including well logging or inversion. The sixth processing unit is used to calculate the error Δx between the pinch-out point location and the actual location of the formation based on the included angle θ between the top and bottom surfaces of the sandstone formation, the dip angle α of the top surface of the sandstone, the dominant frequency f of the seismic data within the sandstone time window, and the propagation velocity v of the seismic waves in the sandstone formation. The seventh processing unit is used to obtain the actual location of the pinch-out point by extending the calculated error distance along the top surface of the formation in the upward dip direction based on the identified pinch-out point location.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the stratigraphic pinch-out point identification method based on any one of claims 1-5.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the formation pinch-out point identification method based on any one of claims 1-5.

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