Thin reservoir evaluation method and system based on pre-stack coherence, medium and equipment
Through pre-stack coherence technology, the problem of thin reservoirs being difficult to identify thin reservoirs is solved, and a higher precision thin reservoir structure and property recognition is achieved.
Patent Information
- Application Number
- CN202311422096.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-05-02
AI Technical Summary
The prior art is difficult to effectively identify and describe the structure and properties of thin reservoirs, especially in post-stack seismic data, where the waveform changes caused by heterogeneity of thin layers are small and difficult to identify.
The thin reservoir evaluation method based on pre-stack coherence is adopted. By the wave field separation of seismic channel sets of common center points before stack, the matrix wave and disturbance wave wave are separated, and the coherence coefficient and energy changes of the disturbance wave field are calculated. Combined with the forward simulation results, the comprehensive evaluation of thin reservoirs is achieved.
It improves the identification accuracy of thin reservoir structure and properties, is easy to achieve, and can more accurately characterize the heterogeneity and structural characteristics of thin reservoirs.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of petroleum geophysical exploration, and in particular relates to a thin reservoir evaluation method, system, medium and equipment based on prestack coherence. Background Art
[0002] A lot of research has been done on the identification and description of thin reservoirs. Commonly used technologies include post-stack seismic attribute technology, spectral decomposition notch technology, edge detection technology, etc. With the increasing demand for exploration accuracy, people realize that post-stack seismic attributes can no longer meet the current identification of thin reservoir structures and properties, so the waveform changes caused by different layered structures have been studied in depth. Studies have shown that when waveforms are obtained from two different observation points, their similarity predicts the impact of different reservoir heterogeneity on seismic waves. The coherence coefficient is a statistical measurement method for waveform similarity, and its correlation predicts the heterogeneity of the structure and properties of thin reservoirs.
[0003] Coherence technology is widely used in the characterization of underground rivers, faults and cracks, sediment pinch-out lines, etc., mainly because rivers, sand body changes, fault development zones, etc. show strong heterogeneity, and their heterogeneous changes are manifested as coherent anomalies. Usually, coherence technology is mainly used for post-stack seismic data. Pre-stack seismic data has richer information and is more sensitive to the changes in waves caused by heterogeneity. Therefore, for crack detection, pre-stack coherence technology has also been applied to pre-stack data in recent years, providing a method for identifying faults inside the formation and obtaining clearer fractures. Compared with cracks, the wave changes caused by the heterogeneity of thin layers are smaller and difficult to identify in post-stack gathers. Therefore, it is necessary to predict thin reservoirs based on pre-stack coherence technology.
[0004] The website of the State Intellectual Property Office (2015.07) discloses a fracture prediction method based on pre-stack coherence. The method first processes the actual pre-stack seismic data to obtain pre-stack seismic gathers after dynamic correction, and then uses the pre-stack azimuth common center point seismic gathers to perform azimuth and offset stacking to obtain azimuth and offset stacking gathers; the stacked azimuth and offset stacking gathers are then subjected to coherence volume calculation based on the covariance matrix to obtain a fracture coherence volume, and then the fracture coherence volume is subjected to fracture parameter inversion calculation to obtain the final fracture development azimuth and development intensity.
[0005] CNKI Foreign Oil and Gas Exploration (1992.09) published the document "Seismic Mapping of Complex Reflection Surfaces Using Common Reflection Element (CRE) Method". The core of the CRE stacking method is the pre-stack coherence analysis of the reflection signal. This allows the selection of shot-detector pairs from a known data set that provides the best image for the inclined reflection surface element. For non-horizontal reflection surface elements, the shot-detector pairs have an asymmetric distribution in space relative to the center point. The coherence analysis is performed on two variables, namely the curvature radius of the reflection wavefront and the angle of incidence.
[0006] China National Knowledge Infrastructure Petroleum Geology and Engineering (2015.11) published the document "Application of Prestack All-round Fracture Prediction Technology Method". Due to the limitations of data structure and prediction method, the conventional prestack fracture prediction method has inaccurate prediction results and multiple solutions. The prestack all-round fracture prediction method is to construct an all-round common reflection angle gather based on all-round seismic acquisition data, and use the AVAZ prestack inversion method to predict the fracture development intensity and direction; the all-round common reflection angle gather contains all the real azimuth information of the formation, which is conducive to the prediction of azimuthal anisotropy; AVAZ prestack inversion can obtain the only solution for fracture direction and development intensity. Summary of the invention
[0007] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and to provide a thin reservoir evaluation method, system, medium and equipment based on prestack coherence.
[0008] The present invention is achieved through the following technical solutions:
[0009] The first aspect of the present invention provides a thin reservoir evaluation method based on prestack coherence, which uses prestack common-center point seismic traces to separate matrix waves from disturbance waves through wave field separation; then, the coherence coefficient of the prestack common-center point seismic traces and the matrix wave and the energy change of the disturbance wave field are obtained for the thin reservoir section, and finally, a comprehensive evaluation of the thin reservoir is achieved based on the forward simulation results of the study area.
[0010] A further improvement of the present invention is:
[0011] The method comprises:
[0012] Step 1: Obtain the corrected pre-stack common center point seismic gathers;
[0013] Step 2: Perform wave field separation;
[0014] Step 3: Obtain the coherence coefficient between the prestack common center point seismic gathers and matrix waves in the thin reservoir section and the energy change of the disturbance wave field;
[0015] Step 4: Based on the forward simulation results of thin reservoirs with different structures and properties in the study area, the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties is established to achieve the evaluation of thin reservoirs.
[0016] A further improvement of the present invention is:
[0017] The first step is to obtain the corrected pre-stack common center point seismic gathers, specifically:
[0018] The actual field seismic data is preprocessed to obtain the pre-stack common-center seismic gather P(i, j) after dynamic correction, where i is the i-th track of the common-center gather and j is the sampling time.
[0019] A further improvement of the present invention is:
[0020] The preprocessing includes filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and gather extraction processing methods.
[0021] A further improvement of the present invention is:
[0022] The second step is to perform wave field separation, and the specific operations include:
[0023] The pre-stack common center point seismic traces obtained in the first step after dynamic correction are stacked and averaged as the matrix wave of the seismic wave;
[0024] The thin reservoir is regarded as a disturbance in the formation. Therefore, the seismic gather P(i, j) can be decomposed into the matrix wave propagating in the formation and the disturbance wave in the thin reservoir. The matrix wave is the average fluctuation of the P(i, j) gather, which is obtained by formula (1):
[0025]
[0026] A further improvement of the present invention is:
[0027] The second step also includes:
[0028] Each trace of the pre-stack common-center seismic gather is considered to be the superposition of the matrix wave and the disturbance wave. Each common-center seismic gather is subtracted from the matrix wave to obtain the disturbance wave of the corresponding trace, which is obtained by formula (2):
[0029] Ps(j)=P(i,j)-P1(j) (2)
[0030] Where P1(j) is the matrix wave propagating in the formation, n is the number of channels in the common center point gather, and Ps(j) is the disturbance wave corresponding to the matrix wave.
[0031] A further improvement of the present invention is:
[0032] The specific operations of the third step include:
[0033] Then, the coherence coefficient between the matrix wave P1(j) and the prestack common center point seismic gather P(i, j) of the thin reservoir segment is calculated using formula (3):
[0034]
[0035] Among them, j1 and j2 represent the thin reservoir development section, p1 and p(i) are the average values of the matrix wave propagated in the formation and the original gather in the reservoir development section.
[0036] A second aspect of the present invention provides a thin reservoir evaluation system based on prestack coherence, comprising:
[0037] An acquisition unit, used for acquiring a corrected pre-stack common center point seismic gather;
[0038] A wave field separation unit, used for performing wave field separation;
[0039] The coherence coefficient and energy change obtaining unit is used to obtain the coherence coefficient of the prestack common center point seismic gather and the matrix wave in the thin reservoir section and the energy change of the disturbance wave field;
[0040] The reservoir evaluation unit is used to establish the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties based on the forward simulation results of thin reservoirs with different structures and properties in the study area, so as to realize the evaluation of thin reservoirs.
[0041] The third object of the present invention is to provide a computer-readable storage medium, which stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps in the thin reservoir evaluation method based on prestack coherence as described above.
[0042] A fourth aspect of the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the thin reservoir evaluation method based on prestack coherence as described above.
[0043] Compared with the prior art, the present invention has the following beneficial effects:
[0044] The present invention introduces pre-stack gathers into the identification of thin reservoirs, applies wave field separation means and coherence analysis in the pre-stack gathers, realizes the structure and prediction of thin reservoirs, and has higher accuracy and is easy to realize. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Figure 1 It is a flow chart of a thin reservoir evaluation method based on prestack coherence of the present invention;
[0046] Figure 2It is the forward simulation result of the common center point gather and matrix wave of a structural thin reservoir;
[0047] Figure 3 It is the forward simulation result of the common center point gather and matrix wave of another thin reservoir structure;
[0048] Figure 4 It is the forward simulation result of disturbance wave of common center point gather of thin reservoir of a certain nature;
[0049] Figure 5 It is the forward simulation result of the disturbance wave of the common center point gather of another structural thin reservoir. DETAILED DESCRIPTION
[0050] The present invention is further described in detail below in conjunction with the accompanying drawings:
[0051] The changes in the structure and properties of thin reservoirs are manifested as the heterogeneity of the strata, causing changes in the morphology of the propagating waves. This change can be represented by the coherence coefficient. For inhomogeneous media, when the waveforms are obtained through two different observation points, their similarity predicts the impact of different reservoir heterogeneities on seismic waves. The coherence coefficient is a statistical measurement method for waveform similarity, and its correlation predicts the heterogeneity of the structure and properties of thin reservoirs. The present invention introduces prestack seismic traces into thin reservoir identification, separates coherent waves from scattered waves through wave fields, and then calculates the coherence properties between different waves, and realizes the identification of thin reservoirs in combination with forward simulation.
[0052] The present invention utilizes pre-stack common-center point seismic gathers to separate matrix waves from disturbance waves by means of wave field separation; then, the coherence coefficient between the pre-stack common-center point seismic gathers and the matrix waves and the energy change of the disturbance wave field are obtained for the thin reservoir section, and finally, a comprehensive evaluation of the thin reservoir is achieved based on the forward simulation results of the study area.
[0053] The present invention provides a thin reservoir evaluation method based on prestack coherence, and an embodiment of the method is as follows:
[0054] [Example 1]
[0055] like Figure 1 As shown, the method includes:
[0056] Step 1: Obtain the corrected pre-stack common center point seismic gathers;
[0057] Specifically:
[0058] Preprocessing is performed on actual field seismic data, including filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and track gathering, etc., to obtain the pre-stack common center point seismic track gather P (i, j) after dynamic correction, where i is the i-th track of the common center point track gather and j is the sampling time;
[0059] Processing methods such as filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and extraction of gathers are all existing technologies and will not be described in detail here.
[0060] Step 2: Perform wave field separation;
[0061] Specific operations include:
[0062] The pre-stack common center point seismic traces obtained in the first step after dynamic correction are stacked and averaged as the matrix wave of the seismic wave;
[0063] The thin reservoir is regarded as a disturbance in the formation. Therefore, the seismic gather P(i, j) can be decomposed into the matrix wave propagating in the formation and the disturbance wave in the thin reservoir. The matrix wave is the average fluctuation of the P(i, j) gather, which is obtained by formula (1):
[0064]
[0065] Each trace of the pre-stack common-center seismic gather is considered to be the superposition of the matrix wave and the disturbance wave. Each common-center seismic gather is subtracted from the matrix wave to obtain the disturbance wave of the corresponding trace, which is obtained by formula (2):
[0066] Ps(j)=P(i,j)-P1(j) (2)
[0067] Where P1(j) is the matrix wave propagating in the formation, n is the number of channels in the common center point gather, and Ps(j) is the disturbance wave corresponding to the matrix wave.
[0068] Step 3: Obtain the coherence coefficient between the prestack common center point seismic gathers and matrix waves in the thin reservoir section and the energy change of the disturbance wave field;
[0069] Specific operations include:
[0070] Formula (3) is used to calculate the coherence coefficient between the matrix wave P1(j) and the prestack common center point seismic gather P(i, j) of the thin reservoir segment:
[0071]
[0072] Among them, j1 and j2 represent the thin reservoir development section, p1 and p(i) are the average values of the matrix wave propagated in the formation and the original gather in the reservoir development section.
[0073] Step 4: Based on the forward simulation results of thin reservoirs with different structures and properties in the study area, the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties is established to achieve the evaluation of thin reservoirs.
[0074] The coherence coefficient and energy distribution between different traces of the disturbance wave Ps(j) are calculated according to formula (3), and finally the thin reservoir identification model is given according to the forward simulation results of the study area.
[0075] In order to verify the effectiveness of the technical method of the present invention, thin reservoirs with different structures are used. Through wave field separation, it can be seen that when the thickness of the thin reservoir is thinner and the number of layers is more (such as Figure 2 As shown in Figure 2, the worse the similarity between the common center point gather and the matrix wave, the thinner the reservoir is, the thicker it is, and the fewer the layers are (e.g. Figure 3 Therefore, the number and thickness (structure) of thin reservoirs can be characterized by the coherence coefficients of different gathers and matrix waves.
[0076] Figure 4 and Figure 5 The common center point gather disturbance wave fields of two thin reservoirs with different properties show that the thin reservoir is thin and has many layers (such as Figure 4 As shown), thin reservoirs are relatively thick and have fewer layers (such as Figure 5 As shown in Figure 1, thin layers of different properties have different energy distributions of scattered waves, and their similarity deteriorates. By studying the development characteristics of thin layers in different work areas and combining the recognition template obtained by forward simulation, pre-stack evaluation of thin reservoirs can be achieved.
[0077] The present invention provides a thin reservoir evaluation system based on prestack coherence, and the embodiments of the system are as follows:
[0078] [Example 2]
[0079] The system comprises:
[0080] The acquisition unit is used to obtain the corrected pre-stack common center point seismic gathers and perform the following operations:
[0081] Preprocessing is performed on actual field seismic data, including filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and track gathering, etc., to obtain the pre-stack common center point seismic track gather P (i, j) after dynamic correction, where i is the i-th track of the common center point track gather and j is the sampling time;
[0082] Processing methods such as filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and extraction of gathers are all existing technologies and will not be described in detail here.
[0083] The wave field separation unit is used to perform wave field separation and performs the following operations:
[0084] The pre-stack common center point seismic traces obtained in the first step after dynamic correction are stacked and averaged as the matrix wave of the seismic wave;
[0085] The thin reservoir is regarded as a disturbance in the formation. Therefore, the seismic gather P(i, j) can be decomposed into the matrix wave propagating in the formation and the disturbance wave in the thin reservoir. The matrix wave is the average fluctuation of the P(i, j) gather, which is obtained by formula (1):
[0086]
[0087] Each trace of the pre-stack common-center seismic gather is considered to be the superposition of the matrix wave and the disturbance wave. Each common-center seismic gather is subtracted from the matrix wave to obtain the disturbance wave of the corresponding trace, which is obtained by formula (2):
[0088] Ps(j)=P(i,j)-P1(j) (2)
[0089] Where P1(j) is the matrix wave propagating in the formation, n is the number of channels in the common center point gather, and Ps(j) is the disturbance wave corresponding to the matrix wave.
[0090] The coherence coefficient and energy change obtaining unit is used to obtain the coherence coefficient of the prestack common center point seismic gathers and matrix waves in the thin reservoir section and the energy change of the disturbance wave field. The following operations are performed:
[0091] Formula (3) is used to calculate the coherence coefficient between the matrix wave P1(j) and the prestack common center point seismic gather P(i, j) of the thin reservoir segment:
[0092]
[0093] Among them, j1 and j2 represent the thin reservoir development section, p1 and p(i) are the average values of the matrix wave propagated in the formation and the original gather in the reservoir development section.
[0094] The reservoir evaluation unit is used to establish the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties based on the forward simulation results of thin reservoirs with different structures and properties in the study area, so as to realize the evaluation of thin reservoirs.
[0095] The present invention also provides a computer-readable storage medium, and an embodiment of the computer-readable storage medium is as follows:
[0096] [Example 3]
[0097] The computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of the thin reservoir evaluation method based on prestack coherence as described in the first embodiment.
[0098] The present invention also provides a computer device, and the embodiments of the computer device are as follows:
[0099] [Example 4]
[0100] The computer device includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the thin reservoir evaluation method based on prestack coherence as described in the first embodiment.
[0101] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
[0102] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.
Claims
1. A thin reservoir evaluation method based on prestack coherence, characterized in that: The matrix wave and the disturbance wave are separated by wave field separation using prestack common-midpoint seismic gathers. Then, the coherence coefficient between the prestack common-midpoint seismic gathers and the matrix wave and the energy change of the disturbance wave field are calculated for the thin reservoir section. Finally, a comprehensive evaluation of the thin reservoir is achieved based on the forward modeling results of the study area.
2. The thin reservoir evaluation method based on prestack coherence according to claim 1, characterized in that: The method comprises: Step 1: Obtain the corrected pre-stack common center point seismic gathers; Step 2: Perform wave field separation; Step 3: Obtain the coherence coefficient between the prestack common center point seismic gathers and matrix waves in the thin reservoir section and the energy change of the disturbance wave field; Step 4: Based on the forward simulation results of thin reservoirs with different structures and properties in the study area, the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties is established to achieve the evaluation of thin reservoirs.
3. The thin reservoir evaluation method based on prestack coherence according to claim 2, characterized in that: The first step is to obtain the corrected pre-stack common center point seismic gathers, specifically: The actual field seismic data is preprocessed to obtain the pre-stack common-center seismic gather P(i, j) after dynamic correction, where i is the i-th track of the common-center gather and j is the sampling time.
4. The thin reservoir evaluation method based on prestack coherence according to claim 3 is characterized in that: The preprocessing includes filtering, deconvolution, multiple wave suppression, velocity analysis, dynamic correction, and gather extraction processing methods.
5. The thin reservoir evaluation method based on prestack coherence according to claim 2 is characterized in that: The second step is to perform wave field separation, and the specific operations include: The pre-stack common center point seismic traces obtained in the first step after dynamic correction are stacked and averaged as the matrix wave of the seismic wave; The thin reservoir is regarded as a disturbance in the formation. Therefore, the seismic gather P(i, j) can be decomposed into the matrix wave propagating in the formation and the disturbance wave in the thin reservoir. The matrix wave is the average fluctuation of the P(i, j) gather, which is obtained by formula (1):
6. The thin reservoir evaluation method based on prestack coherence according to claim 5, characterized in that: The second step also includes: Each trace of the pre-stack common-center seismic gather is considered to be the superposition of the matrix wave and the disturbance wave. Each common-center seismic gather is subtracted from the matrix wave to obtain the disturbance wave of the corresponding trace, which is obtained by formula (2): Ps(j)=P(i,j)-P1(j) (2) Where P1(j) is the matrix wave propagating in the formation, n is the number of channels in the common center point gather, and Ps(j) is the disturbance wave corresponding to the matrix wave.
7. The thin reservoir evaluation method based on prestack coherence according to claim 6, characterized in that: The specific operations of the third step include: Then, the coherence coefficient between the matrix wave P1(j) and the prestack common center point seismic gather P(i, j) of the thin reservoir segment is calculated using formula (3): Among them, j1 and j2 represent the thin reservoir development section, p1 and p(i) are the average values of the matrix wave propagated in the formation and the original gather in the reservoir development section.
8. A thin reservoir evaluation system based on prestack coherence, characterized in that: include: An acquisition unit, used for acquiring a corrected pre-stack common center point seismic gather; A wave field separation unit, used for performing wave field separation; The coherence coefficient and energy change obtaining unit is used to obtain the coherence coefficient of the prestack common center point seismic gather and the matrix wave in the thin reservoir section and the energy change of the disturbance wave field; The reservoir evaluation unit is used to establish the relationship between the field thin reservoir coherence coefficient and the reservoir structure and properties based on the forward simulation results of thin reservoirs with different structures and properties in the study area, so as to realize the evaluation of thin reservoirs.
9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of the thin reservoir evaluation method based on prestack coherence as described in any one of claims 1 to 7.
10. A computer device, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the thin reservoir evaluation method based on prestack coherence as described in any one of claims 1 to 7.