Method for calculating fracture strength based on depth domain seismic data volume

Abstract

The invention discloses a method for calculating fracture intensity based on a depth domain seismic data volume, and relates to the technical field of geophysical prospecting data processing interpretation, and the method comprises the following steps: S1, setting each center incident angle parameter by using angle domain common imaging point gather data, reconstructing center incident angle gather data, introducing horizon data, and obtaining an angle domain common imaging point gather data set; obtaining horizon data of a series of central incident angle gathers; s2, performing color fusion-related three-component data calculation by using the horizon data of each center incident angle gather, and performing color component reconstruction assignment processing on related parameter data values to obtain first color three-component data of related calculation points; and S3, performing reconstruction processing related to the crack strength on the related first color component again to obtain a second color component, and performing color fusion processing on the second color component to obtain a color fusion planar graph related to the crack development strength. And the crack development condition of the related target interval can be evaluated by using the color fusion plane graph.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical prospecting data processing and interpretation, and more specifically to a method for calculating fracture strength based on depth domain seismic data volume. Background Art

[0002] Fracture prediction plays an important role in oil and gas exploration and is also the focus of geophysical inversion research. When fractures are developed in a reservoir, they play a great role in the communication of the reservoir. Drilling into fracture + pore reservoirs often results in high-yield industrial oil and gas flows. Therefore, finding fracture reservoirs in the early stages of exploration is the focus of exploration. Explorers hope to find reservoirs where fractures and pores are superimposed. For example, in the marine reefs and beaches (Feixianguan Formation, Changxing Formation, and Maokou Formation, etc.) and terrestrial tight sandstone oil and gas and shale gas exploration in the Sichuan Basin, fracture prediction is also relatively important.

[0003] There are many conventional fracture prediction techniques, which can basically be divided into two categories: pre-stack and post-stack inversion. After inversion or attribute calculation, attribute data bodies for fracture prediction can be obtained. In seismic exploration, the amplitude, velocity, two-way travel time, and frequency in seismic data of different orientations have different response characteristics to fractures, which also becomes the premise of fracture prediction. According to research data, when the underground target layer is in a state of developing fractures, the amplitude and two-way travel time of seismic P waves have the characteristics of changing with azimuth when passing through the fracture body. For example, Xiangyang Li published "Fracture detection using azimuthal variation of P-wave moveout fromorthogonal seismic survey lines" in "Geophysics" in 1999. Research data show that: ① The two-way travel time of the reflected P wave at the top of the fracture body does not change with azimuth, and the amplitude changes slightly with azimuth, and the anisotropy is not obvious. ② The reflected P wave at the bottom of the fracture body shows strong azimuthal anisotropy. The P wave reflection amplitude and two-way travel time are related to the survey line and the fracture orientation. When the survey line is parallel to the fracture, the amplitude is the strongest and the two-way travel time is the shortest. As the angle between the survey line and the fracture increases, the amplitude gradually weakens and the two-way travel time gradually increases. When the survey line is perpendicular to the fracture direction, the amplitude is the weakest and the two-way travel time is the longest. It can be seen that the P wave shows strong azimuthal anisotropy when passing through the fracture body. The degree of influence of the fracture on the P wave response depends on the angle between the fracture orientation and the survey line and the scale of a certain open fracture system underground. This phenomenon has a greater impact on the travel time of the bottom layer. In the depth domain, due to the addition of velocity data, the anisotropy of the different azimuthal depth data generated by the bottom layer when the P wave passes through the fracture body will be more obvious.

[0004] Conventional fracture prediction techniques are mostly calculated based on time-domain seismic data, but time-domain seismic data are often affected by layer velocity changes, resulting in inaccurate seismic imaging and reflection event axes that do not match the actual geological conditions. Therefore, using time-domain gathers and post-stack seismic data to predict fractures will result in large calculation errors and risks. Summary of the invention

[0005] In order to overcome the defects existing in the above-mentioned prior art, the present invention discloses a method for calculating fracture strength based on depth domain seismic data volume. The purpose of the present invention is to solve the above-mentioned and other shortcomings in conventional fracture prediction technology in the prior art. The present invention calculates the fracture development strength based on the layer data of the center incident angle gather reconstructed in the depth domain and color fusion processing, and uses the layer data of the bottom of the target layer on the angle domain common imaging point gather data of a series of center incident angle depth domains to predict and evaluate the fracture development strength, which can achieve the purpose of accurately predicting the fracture development situation on the plane of the target layer in the study area. The present invention evaluates the fracture development situation of the relevant target layer segment, thereby reducing drilling risks and improving the economic benefits of related oil and gas exploration.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is: A method for calculating fracture strength based on a depth domain seismic data volume comprises the following steps: S1. Use the angle domain common imaging point gather data to set the parameters of each central incidence angle, reconstruct the central incidence angle gather data and introduce the layer data into it to obtain a series of layer data of the central incidence angle gather.

[0007] Preferably, the step S1 comprises the following steps: S11, determining the target layer position data of each three-dimensional angle domain common imaging point gather; Preferably, in the step S11, a limited incident angle range is set for superposition of the common imaging point gather data in each angle domain for the target layer to obtain a post-stack data volume in the depth domain; well-seismic calibration is performed on the post-stack data volume in the depth domain using logging data and geological stratification data to determine the bottom reflection of the target layer in the well; the target layer seed point characteristics and search parameters are determined based on the bottom reflection characteristics, and the seismic data volume in the depth domain is automatically tracked to obtain the position of the entire target layer on the post-stack seismic data volume, thereby obtaining the stratigraphic data of the target layer for each three-dimensional angle domain common imaging point gather point.

[0008] In the above step S11, the layer data of the target layer of each 3D angle domain common imaging point gather (ADCIG) is determined. The target layer generally refers to the bottom interface reflection of the target layer. The specific operation is to set the limited incident angle range for the target layer to stack each angle domain common imaging point gather (ADCIG) data to obtain the post-stack data volume in the depth domain. The stacked incident angle is generally less than 30 o . The well-seismic calibration of the depth domain post-stack data volume is carried out using logging data and geological stratification data to determine the bottom reflection of the target layer in the well. According to the bottom reflection characteristics and the target layer seed point characteristics and search parameters, the depth domain seismic data volume is automatically tracked to obtain the position of the entire target layer on the post-stack seismic data volume, thereby obtaining the stratigraphic data of the target layer of each three-dimensional angle domain common imaging point gather (ADCIG) point. In general, angle domain common imaging point gather data refers to the use of PSDM based on double square root equations to obtain underground local offset distance gathers, and the established relationship between the local offset distance direction wave number and the depth direction wave number and the incident angle is used to obtain angle domain common imaging point gather data. The seismic gather data is in the depth domain and has azimuth and incident angle information. In principle, the requirement for seismic data is seismic data collected with a wide azimuth (WAZ), which helps to predict and evaluate the intensity of fracture development in the depth domain.

[0009] S12, setting the reconstructed angle domain common imaging point gather data within a certain incident angle range with a certain incident angle as the center as the central incident angle parameter, and performing data reconstruction to obtain the relevant central incident angle reconstructed gather data; In general, the azimuth angle of the angle domain gather is determined by taking the north direction as 0. o , clockwise rotation is 360 o , the angle between the vector direction of the gun-check point line and the true north direction is set as the azimuth. For example, the setting method for reconstructing a certain central incident angle data is to determine the central incident angle, and the azimuth within a certain incident angle range centered on the central incident angle is 360 o The gather data within the range is reconstructed to obtain the gather data reconstructed at the central incidence angle. In general, a certain incidence angle range refers to the positive and negative 1 with the central incidence angle as the center. o The central incident angle is generally set to θ, which belongs to [5 o , 30 o ], and the gather data within this range are grouped into a central incidence angle gather. In actual operations, a series of central incidence angles, relevant incidence angle ranges and other parameters can be determined according to the known depth position of the target layer of the well, the intensity of fracture development and the amplitude of the angle domain common imaging point gather data, and the gather data reconstruction for each central incidence angle can be implemented.

[0010] S13, introducing the target layer horizon data into the center incidence angle reconstruction gather data to obtain the horizon data of the center incidence angle reconstruction gather data; Preferably, in the step S13, a three-dimensional coordinate system is established and the data of a certain angle domain common imaging point gather are projected into the three-dimensional coordinate system, and a two-dimensional gather profile is reconstructed for the angle domain gather data, and the stratigraphic data is introduced from the minimum incident angle data channel, and the seed point characteristics and position are determined, and the relevant search time window is set, and the stratigraphic tracking of the target layer is automatically carried out for other seismic data channels in the gather, so as to obtain the stratigraphic data of the reconstructed central incident angle gather data.

[0011] The reconstruction of the two-dimensional gather profile is as follows: establishing a three-dimensional coordinate, the coordinate is the origin of the gather data with the center being the common imaging point in the angle domain, the x and y axes of the coordinate plane contain two coordinates, namely the incident angle coordinate and the azimuth coordinate system, the azimuth setting is 0 in the north direction o , clockwise rotation is 360 o The incident angle coordinate system does not distinguish between positive and negative. The incident angle and azimuth information of the gather points in the angle domain gather data are projected into the coordinate plane, and the amplitude data of the depth domain of the gather data is projected into the three-dimensional system based on the z direction of the three-dimensional coordinate system as the depth unit. A profile line is drawn in the set direction from the origin of the three-dimensional coordinate. When the profile line intersects with the azimuth line of the reconstructed central incident angle gather, a two-dimensional gather profile is established along the clockwise direction according to the central incident angle, its range, and the azimuth line.

[0012] Among them, the position of the projection of the central incident angle data point on the three-dimensional coordinate plane is the azimuth line, and the layer data is introduced from the minimum incident angle data channel. Specifically, it refers to projecting the layer data (xj, yj, hj) to the data point (xj, yj, hj) on the minimum incident angle data channel, and automatically tracking according to the reflection amplitude characteristics of the seed point and the search window value parameters to obtain the layer data of the two-dimensional gather section, thereby obtaining the layer data of the reconstructed central incidence angle gather data.

[0013] Generally, the search window value for automatic layer tracking is set to 16m.

[0014] S14. According to the needs of fracture prediction and evaluation, a series of central incidence angle parameters are set, and the depth domain layer data of each central incidence angle is calculated according to the above method.

[0015] In the above steps, in general, the number of central angle incident angles should be greater than or equal to three, and any central angle of incidence θi belongs to [5 o , 30 o ]. Among them, the central incident angle and its related range can be determined according to the crack prediction accuracy, expert experience and actual gather conditions.

[0016] S2. Utilize the layer data of each center incident angle gather to perform three-component data calculation on color fusion, and perform color component reconstruction and value assignment processing on relevant parameter data values ​​to obtain the first color three-component data of relevant calculation points.

[0017] Preferably, the S2 step comprises the following steps: S21, using the layer data of each center incidence angle gather to calculate the three-component parameter data about color fusion; In general, the three-component data calculation for color fusion is performed using the layer data of the gathers at each central incidence angle at each CDP (central incidence angle parameter) point. The calculation method for the three-component parameters of any CDP point is as follows: The calculation of the first parameter of the color component is specifically as follows: for a certain central incident angle of a certain CDP point, the discrete coefficient is calculated using the depth domain layer data to obtain the discrete coefficient data value of the central incident angle of the CDP; and so on, the discrete coefficient calculation of each central incident angle of the CDP point is completed; the gradient data value of the discrete coefficient obtained for each central incident angle of the CDP point is calculated, thereby obtaining the first parameter data value calculated for this type of color component at the CDP point.

[0018] The calculation of the second parameter of the color component is as follows: Use the depth domain layer data of a certain central incident angle of each CDP point to establish a two-dimensional coordinate system, where the horizontal axis is the angle and the vertical axis is the layer data. o -360 o The azimuth angle and its corresponding layer data are projected in a two-dimensional coordinate system; the relevant intersection data points are fitted with a least squares binary curve to obtain a relevant fitting curve and a functional relationship; the center line is set using the average value of the center incident angle layer data, and the intersection area between the fitting curve and the set center line is calculated; after the intersection area is subjected to relevant mathematical calculations, the calculated result is used as the fitting area of ​​the CDP point; and so on, the calculation of the fitting area of ​​each center incident angle of the CDP point is completed; and the gradient data value of the fitting area obtained for each center incident angle of the CDP point is calculated, so as to obtain the second parameter data value of the CDP point calculated for the type of color component.

[0019] The calculation of the third parameter of the color component is specifically as follows: the maximum data value is selected using the depth domain layer data of each central incident angle related to each CDP point; and the gradient data value is calculated for the maximum data value of the layer data of a series of central incident angles; and the gradient data value is used as the third parameter data value of the CDP point for this type of color component.

[0020] In the present invention, by analogy, the calculation of the three parameter data values ​​for color component calculation of each CDP point on the plane is completed. The three color components refer to R, G, and B. The above calculation method can determine the calculation method corresponding to the three color components (R, G, and B) according to relevant expert experience, color fusion test results, etc., that is, one color component corresponds to one parameter calculation method.

[0021] S22. Reconstruct the color component data values ​​before the color component fusion processing by using the three parameter data values ​​about the color component calculation of each CDP point to obtain three first color component data values ​​of each CDP point.

[0022] In the above steps, the calculation formula is reconstructed according to the relevant color fusion data values, and each three-parameter data value is converted into a first color component data value, thereby laying a foundation for subsequent color fusion processing.

[0023] Preferably, in step S22, the calculation formula for reconstructing the data value of the relevant color fusion is: in, is a parameter data value calculated for a certain color component, The first color component data value calculated for color fusion, =max{ }, =min{ }, [] is the calculation symbol for taking positive integers, and P is a constant.

[0024] In the present invention, P=250 is taken. In actual operation, the value of P can be determined according to the display requirements of the results of the relevant color fusion processing and the experience of relevant experts.

[0025] S3. Reconstruct the crack intensity again on the related first color component, obtain the second color component, and then perform color fusion processing on it to obtain a color fusion plane map of the crack development intensity.

[0026] Preferably, the S3 step comprises the following steps: S31, using relevant fracture prediction data to classify fracture intensity levels on the target layer plane of the study area, setting relevant color component reconstruction coefficients according to relevant fracture intensity levels, performing data reconstruction processing on three first color components of each CDP point, and obtaining relevant second color components; Preferably, in the step S31, the depth-domain post-stack seismic data volume is used to calculate the seismic attributes related to the fracture strength and extract the average data value of the seismic attributes of the target layer segment; the fracture strength data on the well and the average data value of the seismic attributes are used to divide the threshold values ​​of the relevant different fracture strength levels, and set the reconstruction coefficients of the different fracture strength levels; and the second color component is reconstructed using the relevant reconstruction coefficients, the fracture strength levels divided by the CDP points on the plane, and the data values ​​of the first color components.

[0027] Preferably, in the step S31, the reconstruction process of the relevant second color component is: Among them, Aij is the reconstructed data value of the second color component of the jth category of the ith CDP point, Kij is the reconstruction coefficient data value of the jth seismic attribute of the CDP point, Dij is the first color component data value of the CDP and the jth category before reconstruction; n is the number of seismic attributes for calculating fracture strength, which is generally greater than or equal to one, and [] is the calculation symbol for taking positive integers.

[0028] Preferably, in the S31 step, in actual operation, a relevant post-stack fracture calculation method is used to calculate a series of seismic attribute data bodies for fracture strength calculation based on the depth domain post-stack seismic data body, and the average values ​​of the seismic attribute data of the target layer segment are extracted respectively. According to the well fracture strength division situation, expert experience and reconstruction coefficient setting accuracy, different fracture strength threshold values ​​are divided and the corresponding reconstruction coefficients are set.

[0029] In general, for a certain seismic attribute, the number of related reconstruction coefficients must be greater than or equal to two, and each reconstruction coefficient should be greater than 0 and less than 1. In principle, the reconstruction coefficient is set such that the greater the fracture intensity, the greater the reconstruction coefficient value; otherwise, the smaller the reconstruction coefficient.

[0030] Preferably, in the step S31, the reconstruction coefficient of a certain seismic attribute of each CDP point is determined, and the reconstruction coefficient value of the seismic attribute of the CDP point is determined according to the seismic attribute data value on the plane of the CDP point, the threshold value divided by the seismic attribute, and the set reconstruction coefficient data value corresponding to the relevant threshold value; in addition, the reconstruction coefficient data value of the seismic attribute is used to reconstruct the color components of the three first color components of the CDP point, so as to obtain the three second color reconstruction components on the CDP point.

[0031] Preferably, in the step S31, the seismic attributes used by the three first color components for the calculation of the second color component are different. A first color component can have one or more seismic attributes involved in the calculation of the second color component. In the reconstruction processing calculation of the related second color component, since the calculation of a first color component must have one seismic attribute, three depth domain seismic attribute data for the fracture strength calculation must be calculated.

[0032] Specifically, relevant seismic attributes are used in the calculation, which can be determined based on the test results of the fracture strength of the target layer in the relevant well, expert experience, etc.

[0033] S32, performing color fusion processing on the three second color reconstruction components of each CDP point in the study area to obtain a color fusion plane map of the crack development intensity.

[0034] The present invention uses the bottom interface layer data of a series of central incident angle reconstruction gather data to calculate the fracture development intensity.

[0035] Beneficial effects of the present invention: The present invention provides a method for predicting fractures in the depth domain, by setting a series of central incidence angle parameters for the three-dimensional angle domain common imaging point gather (ADCIG), and reconstructing the relevant central incidence angle gather data to introduce the target layer stratigraphic data; using the stratigraphic data of the relevant central incidence angle gather data to perform secondary color three-component data calculation, and after color fusion, a color fusion plane map for predicting fracture development intensity is obtained. Relevant practical data show that the fracture intensity prediction effect achieved by the present invention is better than the results obtained by conventional fracture prediction technical methods. The technical method of the present invention is used to implement the prediction of fracture development intensity of marine carbonate reservoirs in a certain area, and good results are achieved, which is highly consistent with the actual drilling data in the area, and can guide the layout of relevant horizontal wells and fracturing operations in the area.

[0036] The method for calculating fracture intensity provided by the present invention can finally obtain a color fusion plane map of fracture development intensity, which can predict the fracture development situation on the plane of the target layer in the study area, and can evaluate the fracture development situation of the relevant target layer section, thereby reducing drilling risks and improving the economic benefits of related oil and gas exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0038] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and drawings to fully understand the purpose, characteristics and effects of the present invention.

[0039] In this example, the carbonate rock layer of the Maokou Formation in the Permian system in a 3D work area in central Sichuan was predicted for fractures. After analyzing the relevant seismic acquisition data, it was determined that the relevant seismic data can be used to predict fractures in the depth domain of the target layer. In order to obtain the relevant 3D angle domain common imaging point gather (ADCIG), the time domain gather data was processed by pre-stack depth migration and other related processing.

[0040] Example 1 A method for calculating fracture strength based on depth domain seismic data volume, such as Figure 1 As shown, the following steps are included: S1. Use the angle domain common imaging point gather data to set the parameters of each central incidence angle, reconstruct the central incidence angle gather data and introduce the layer data into it to obtain a series of layer data of the central incidence angle gather; S2, using the layer data of each center incidence angle gather to perform three-component data calculation on color fusion, and performing color component reconstruction and value assignment processing on relevant parameter data values ​​to obtain the first color three-component data of relevant calculation points; S3. Reconstruct the crack intensity again on the related first color component, obtain the second color component, and then perform color fusion processing on it to obtain a color fusion plane map of the crack development intensity.

[0041] Example 2 This embodiment further describes step S1 based on embodiment 1. Step S1 includes the following steps: S11, determining the target layer position data of each three-dimensional angle domain common imaging point gather; In the above step S11, the layer data of the target layer of each 3D angle domain common imaging point gather (ADCIG) is determined. The target layer generally refers to the bottom interface reflection of the target layer. The specific operation is to set the limited incident angle range for the target layer to stack each angle domain common imaging point gather (ADCIG) data to obtain the post-stack data volume in the depth domain. The stacked incident angle is generally less than 30 o. The well-seismic calibration of the depth domain post-stack data volume is carried out using logging data and geological stratification data to determine the bottom reflection of the target layer in the well. According to the bottom reflection characteristics and the target layer seed point characteristics and search parameters, the depth domain seismic data volume is automatically tracked to obtain the position of the entire target layer on the post-stack seismic data volume, thereby obtaining the stratigraphic data of the target layer of each three-dimensional angle domain common imaging point gather (ADCIG) point. In general, angle domain common imaging point gather data refers to the use of PSDM based on double square root equations to obtain underground local offset distance gathers, and the established relationship between the local offset distance direction wave number and the depth direction wave number and the incident angle is used to obtain angle domain common imaging point gather data. The seismic gather data is in the depth domain and has azimuth and incident angle information. In principle, the requirement for seismic data is seismic data collected with a wide azimuth (WAZ), which helps to predict and evaluate the intensity of fracture development in the depth domain.

[0042] S12, setting the central incident angle parameter means determining the reconstructed angle domain common imaging point gather data within a certain incident angle range and all-directional angles with a certain incident angle as the center, and performing data reconstruction to obtain the relevant central incident angle reconstructed gather data; In general, the azimuth angle of the angle domain gather is determined by taking the north direction as 0. o , clockwise rotation is 360 o , the angle between the vector direction of the gun-check point line and the true north direction is set as the azimuth. For example, the setting method for reconstructing a certain central incident angle data is to determine the central incident angle, and the azimuth within a certain incident angle range centered on the central incident angle is 360 o The gather data within the range is reconstructed to obtain the gather data reconstructed at the central incidence angle. In general, a certain incidence angle range refers to the positive and negative 1 with the central incidence angle as the center. o The central incident angle is generally set to θ, which belongs to [5 o , 30 o ], and the gather data within this range are grouped into a central incidence angle gather. In actual operations, a series of central incidence angles, relevant incidence angle ranges and other parameters can be determined according to the known depth position of the target layer of the well, the intensity of fracture development and the amplitude of the angle domain common imaging point gather data, and the gather data reconstruction for each central incidence angle can be implemented.

[0043] S13, introducing the target layer stratigraphic data into the central incident angle reconstruction gather data to obtain the stratigraphic data of the central incident angle reconstruction gather data.

[0044] In the above steps, the specific operation is to establish a three-dimensional coordinate system and project a certain angle domain common imaging point gather data into the three-dimensional coordinate system, and reconstruct a two-dimensional gather profile in the angle domain gather data, introduce the layer data from the minimum incident angle data channel, and determine the seed point characteristics and position, set the relevant search time window, and automatically track the target layer layer for other seismic data channels in the gather to obtain the layer data of the reconstructed central incident angle gather data. Among them, the two-dimensional gather profile reconstruction method is specifically to establish a three-dimensional coordinate, the center of which is the origin of the angle domain common imaging point gather data, and the x and y axes of the coordinate plane contain two coordinates, namely the incident angle coordinate and the azimuth coordinate system, and the azimuth sets the north direction to 0. o , clockwise rotation is 360 o , the incident angle coordinate system does not distinguish between positive and negative. The incident angle and azimuth information of the gather points in the angle domain gather data are projected into the coordinate plane, and the amplitude data of the depth domain of the gather data is projected into the three-dimensional system according to the z direction of the three-dimensional coordinate system as the depth unit. The profile line is drawn in the set direction from the origin of the three-dimensional coordinate. When the profile line intersects with the azimuth line of the reconstructed center incident angle gather, the two-dimensional gather profile is established in the clockwise direction according to the center incident angle and its range and the azimuth line. The position of the projection of the center incident angle data point on the three-dimensional coordinate plane is the azimuth line. The layer data is introduced from the minimum incident angle data channel. Specifically, it refers to the projection of the layer data (xj, yj, hj) to the (xj, yj, hj) data point on the minimum incident angle data channel, and the automatic tracking is carried out according to the reflection amplitude characteristics of the seed point, the search window value and other parameters to obtain the layer data of the two-dimensional gather profile, thereby obtaining the layer data of the reconstructed center incident angle gather data. Generally, the search window value for automatic layer tracking is set to 16m.

[0045] S14. According to the needs of fracture prediction and evaluation, a series of central incidence angle parameters are set, and the depth domain layer data of each central incidence angle is calculated according to the above method.

[0046] In the above steps, in general, the number of central angle incident angles should be greater than or equal to three, and any central angle of incidence θi belongs to [5 o , 30 o ]. Among them, the central incident angle and its related range can be determined according to the crack prediction accuracy, expert experience and actual gather conditions.

[0047] In step S1, first set a series of relevant central incidence angle parameters and divide the common imaging point gather data in the entire angle domain into a series of central incidence angle gathers, and introduce the relevant central incidence angle gathers into the target layer data. In the specific operation of the example, set the incidence angle range to 5 o ~25o , after stacking the incident angle gather range, the three-dimensional post-stack seismic data in the depth domain is obtained; then the logging data, stratigraphic layering information and seismic reflection characteristics are used to calibrate the logging and depth domain seismic data, determine the position of the bottom of the target layer of the Maokou Formation in the well in the seismic profile, and determine the reflection position (strong wave peak) and characteristics of the bottom of the target layer, so as to establish the seed point for horizon tracking. The seed point is the extreme point of the strong wave peak, and the strong wave peak reflection is stably distributed in the whole area with good continuity. The seed point is used to automatically track the seismic data body in the depth domain, and the position of the entire target layer on the post-stack seismic data body in the depth domain is obtained, so as to obtain the horizon data of the target layer of each CDP point.

[0048] Among them, a series of central incident angle parameters are set to divide the gather data. In the actual operation of this exploration area, according to the relevant fracture prediction requirements, expert experience, etc., the central incident angles are set to 8 o , 12 o , 18 o , 25 o , 30 o The five central incident angles are set to positive and negative 1 o After dividing and reconstructing the relevant angle domain common imaging point gather data according to the set central incidence angle parameters, the relevant central incidence angle gather data are obtained.

[0049] In addition, the formation of the horizon data of each center incidence angle reconstruction gather is mainly obtained by introducing the target horizon data of the post-stack seismic data interpretation into the data of each center incidence angle reconstruction gather. In the example, the minimum incidence angle gather (center incidence angle is 8) projected from the horizon data (xj, yj, hj) of the i-th CDP point to the CDP point o ) and set the point as the seed point (the extreme point of the wave crest) and the search parameter (the window is 16m), automatically start tracking on the center incidence angle gather, and obtain the layer data of the center incidence angle gather (the azimuth range is 0 o ~360 o ). Similarly, the target layer is introduced into the gathers of the other four central incidence angles, so as to obtain the layer data of the gather data of the five central incidence angles of each CDP point in the study area.

[0050] Example 3 This embodiment further describes step S2 based on embodiment 2. Step S2 includes the following steps: S21. Calculate the three-component parameter data for color fusion using the layer data of each center incidence angle gather. In general, the three-component data for color fusion is calculated using the layer data of each center incidence angle gather at each CDP (center incidence angle parameter) point. The calculation method of the three-component parameters of any CDP point is as follows: 1) Calculation of the first parameter of the color component. The main steps for calculating the first parameter of the color component are to use the depth domain layer data to calculate the discrete coefficient for a certain central incident angle of a CDP point, and obtain the discrete coefficient data value of the central incident angle of the CDP; and so on, complete the calculation of the discrete coefficient of each central incident angle of the CDP point; calculate the gradient data value of the discrete coefficient obtained for each central incident angle of the CDP point, and thus obtain the first parameter data value of the CDP point calculated for this type of color component.

[0051] 2) Calculation of the second parameter of the color component. The calculation method of the second parameter of the color component is mainly to use the depth domain layer data of a certain central incident angle of each CDP point to establish a two-dimensional coordinate system. The horizontal axis is the angle (θ), and the vertical axis is the layer data. o -360 o The azimuth (θ) and its corresponding layer data are projected in a two-dimensional coordinate system; the relevant intersection data points are fitted with a least squares binary curve to obtain a relevant fitting curve and a functional relationship (f(θ)); the center line is set using the average value of the center incident angle layer data, and the intersection area between the fitting curve and the set center line is calculated; after the intersection area is subjected to relevant mathematical calculations, the calculated result is used as the fitting area of ​​the CDP point; and so on, the calculation of the fitting area of ​​each center incident angle of the CDP point is completed; and the gradient data value of the fitting area obtained for each center incident angle of the CDP point is calculated, so as to obtain the second parameter data value of the CDP point calculated for the type of color component.

[0052] 3) Calculation of the third parameter of the color component. The calculation of the third parameter of the color component mainly uses the depth domain layer data of each central incident angle related to each CDP point to select its maximum data value; and calculates the gradient data value for the maximum data value of the layer data of a series of central incident angles; and uses the gradient data value as the third parameter data value of the CDP point for this type of color component.

[0053] By analogy, the calculation of the three parameter data values ​​for color component calculation of each CDP point on the plane is completed. Among them, the three color components refer to R, G, and B. The above calculation method can determine the calculation method corresponding to the three color components (R, G, and B) based on relevant expert experience, color fusion test results, etc., that is, one color component corresponds to one parameter calculation method.

[0054] S22. Reconstruct the color component data values ​​before the color component fusion processing by using the three parameter data values ​​about the color component calculation of each CDP point to obtain three first color component data values ​​of each CDP point.

[0055] In the above steps, the calculation formula is reconstructed according to the relevant color fusion data value, and each three-parameter data value is converted into the first color component data value, thereby laying the foundation for the subsequent color fusion processing. Among them, the calculation formula of the color component data value of the relevant color fusion is as follows: in, is a parameter data value calculated for a certain color component, The first color component data value calculated for color fusion, =max{ }, =min{ }, [] is the calculation symbol for taking positive integers, and P is a constant.

[0056] In the present invention, P=250 is taken. In actual operation, the value of P can be determined according to the display requirements of the results of the relevant color fusion processing and the experience of relevant experts.

[0057] In step S2, the three-component data calculation for color fusion is implemented according to the layer data of the five central incidence angle gathers of each CDP point, and the relevant parameter data values ​​are processed for color component reconstruction and assignment to obtain the first color three-component data of the relevant calculation point. In the example, based on the experience of relevant color fusion test experts, the color component R is determined to be calculated using the first parameter of the color component; the color component G is determined to be calculated using the second parameter of the color component; and the color component B is determined to be calculated using the third parameter of the color component. After the relevant calculation, the three parameter data values ​​for the color component calculation of each CDP point are obtained; after the data reconstruction calculation for the color component is performed, the relevant first color component data value is obtained.

[0058] Example 4 This embodiment further describes step S3 based on embodiment 3. Step S3 includes the following steps: S31. Use relevant crack prediction data to divide the crack intensity levels on the target layer plane in the study area, set relevant color component reconstruction coefficients according to the relevant crack intensity levels, perform data reconstruction processing on the three first color components of each CDP point, and obtain relevant second color components.

[0059] The main operation mode of this step is to use the depth domain post-stack seismic data volume to calculate the seismic attributes related to the fracture intensity and extract the average data value of the seismic attributes of the target layer; use the fracture intensity data on the well and the average data value of the seismic attributes to divide the threshold values ​​of the relevant different fracture intensity levels and set the reconstruction coefficients of the different fracture intensity levels; use the relevant reconstruction coefficients, the fracture intensity levels divided by the CDP points on the plane and the data values ​​of the first color component to perform reconstruction processing on the second color component. Among them, the calculation formula for the reconstruction processing of the relevant second color component is as follows: Among them, Aij is the reconstructed data value of the second color component of the jth category of the ith CDP point, Kij is the reconstruction coefficient data value of the jth seismic attribute of the CDP point, Dij is the first color component data value of the CDP and the jth category before reconstruction; n is the number of seismic attributes for calculating fracture strength, which is generally greater than or equal to one, and [] is the calculation symbol for taking positive integers.

[0060] Preferably, in actual operation, a series of seismic attribute data bodies for fracture strength calculation based on the depth domain post-stack seismic data body can be calculated by using the relevant post-stack fracture calculation method, and the average values ​​of the seismic attribute data of the target layer segment can be extracted respectively, and the division of different fracture strength threshold values ​​and the setting of the corresponding reconstruction coefficients can be implemented according to the well fracture strength division, expert experience and reconstruction coefficient setting accuracy. In general, for a certain seismic attribute, the number of its related reconstruction coefficients must be greater than or equal to two, and each reconstruction coefficient set should be greater than 0 and less than 1. In principle, the reconstruction coefficient set is based on the principle that the greater the fracture strength, the greater the reconstruction coefficient value; otherwise, the smaller the reconstruction coefficient.

[0061] Preferably, for the reconstruction coefficient determination of a certain seismic attribute of each CDP point, the reconstruction coefficient value of the seismic attribute of the CDP point is determined according to the seismic attribute data value on the plane of the CDP point, the threshold value divided by the seismic attribute, the set reconstruction coefficient data value corresponding to the relevant threshold value, etc. In addition, the reconstruction coefficient data value of the seismic attribute is used to perform color component reconstruction processing on the three first color components of the CDP point, thereby obtaining three second color reconstruction components on the CDP point.

[0062] Preferably, the three first color components are related to the calculation of the second color component. The seismic attributes used by the three are different. One first color component can participate in the calculation of the second color component with one or more seismic attributes. Therefore, in the reconstruction processing calculation of the related second color component, since the calculation of one first color component must have one seismic attribute, three depth domain seismic attribute data related to the fracture strength calculation must be calculated in the present invention. Specifically, the use of related seismic attributes to participate in the calculation can be determined based on the test conditions of the fracture strength of the target layer on the related well, expert experience, etc.

[0063] S32, performing color fusion processing on the three second color reconstruction components of each CDP point in the study area to obtain a color fusion plane map of the crack development intensity.

[0064] In step S3, the three first color component data values ​​on each CDP point are reconstructed again regarding the fracture intensity, and after obtaining the second color component, the color fusion processing is performed on it to obtain a color fusion plane map regarding the fracture development intensity. In actual operation, after calculating the three seismic attributes such as coherence attribute, volume curvature, and variance attribute using the relevant depth domain post-stack seismic data body, different fracture intensity-seismic attribute databases are established according to the fracture development intensity on the well and the different seismic numerical data corresponding to the fracture segment and non-fracture segment; according to the fracture prediction accuracy and expert experience, etc., the seismic attribute threshold values ​​corresponding to different fracture intensities and their corresponding reconstruction coefficient data values ​​are set. In actual operation, for a certain first color component, the coherence attribute data average value of the target layer segment of the depth domain coherent attribute data body is extracted, and the reconstruction coefficient of each CDP point is determined according to the designed series of threshold values ​​and their corresponding reconstruction coefficients, and the second color component data is obtained through calculation. For example, in the prediction of fracture development intensity of carbonate reservoir section of Maokou Formation in this study area, for a certain first color component, four threshold values ​​and their corresponding four reconstruction coefficients are set for the coherence attribute, and the target layer section is obtained by opening a 40m depth time window at the bottom and upper part of the target layer. For example, for a certain CDP point, if the coherence value of the point is 0.76, it is within a certain threshold value (0.6-0.8), and the threshold value corresponds to a reconstruction coefficient of 0.75; then the reconstruction coefficient is used to reconstruct the data of the first color component about the second color component, and the reconstructed data value of the second color component of the CDP point is obtained. Similarly, the reconstruction of the three second color component data of each CDP point on the plane is completed, and then the color of the CDP point is obtained after color fusion processing is performed on it. Similarly, a color fusion plane map about fracture development intensity is completed.

[0065] The color fusion plane map of the fracture development intensity of the Maokou Formation in a certain exploration area in central Sichuan obtained by the technology of the present invention is consistent with the fracture development measured in the well, with a consistency rate of 83.7%, meeting the relevant geological requirements.

[0066] The above is a specific description of the implementation mode of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalents or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for calculating fracture strength based on depth domain seismic data volume, characterized in that: The following steps are involved: S1. Use the angle domain common imaging point gather data to set the parameters of each central incidence angle, reconstruct the central incidence angle gather data and introduce the layer data into it to obtain a series of layer data of the central incidence angle gather; S2, using the layer data of each center incidence angle gather to perform three-component data calculation on color fusion, and performing color component reconstruction and value assignment processing on relevant parameter data values ​​to obtain the first color three-component data of relevant calculation points; S3, reconstructing the crack intensity of the related first color component again, obtaining the second color component, and then performing color fusion processing on it to obtain a color fusion plane map of the crack development intensity.

2. The method for calculating crack strength according to claim 1, characterized in that: The S1 step includes the following steps: S11, determining the target layer position data of each three-dimensional angle domain common imaging point gather; S12, setting the determined reconstructed angle domain common imaging point gather data within a certain incident angle range with a certain incident angle as the center as the central incident angle parameter, and performing data reconstruction to obtain the relevant central incident angle reconstructed gather data; S13, introducing the target layer horizon data into the center incidence angle reconstruction gather data to obtain the horizon data of the center incidence angle reconstruction gather data; S14. According to the needs of fracture prediction and evaluation, a series of central incidence angle parameters are set, and the depth domain layer data of each central incidence angle is calculated according to the above method.

3. The method for calculating crack strength according to claim 2, characterized in that: In the step S11, the common imaging point gather data in each angle domain are set to be superimposed within a limited incident angle range for the target layer to obtain a post-stack data volume in the depth domain; the post-stack data volume in the depth domain is well-seismically calibrated using logging data and geological stratification data to determine the bottom reflection of the target layer in the well; the seed point characteristics and search parameters of the target layer are determined based on the bottom reflection characteristics, and the seismic data volume in the depth domain is automatically tracked to obtain the position of the entire target layer on the post-stack seismic data volume, thereby obtaining the stratigraphic data of the target layer of each three-dimensional angle domain common imaging point gather point.

4. The method for calculating crack strength according to claim 2, characterized in that: In the step S13, a three-dimensional coordinate system is established and a certain angle domain common imaging point gather data is projected into the three-dimensional coordinate system, and a two-dimensional gather profile is reconstructed for the angle domain gather data, and the horizon data is introduced from the minimum incidence angle data channel, and the seed point characteristics and position are determined, and the relevant search time window is set, and the horizon tracking of the target layer is automatically carried out for other seismic data channels in the gather, and the horizon data of the reconstructed center incidence angle gather data is obtained; The reconstruction of the two-dimensional gather profile is as follows: establishing a three-dimensional coordinate, the coordinate is the origin of the gather data with the center being the common imaging point in the angle domain, the x and y axes of the coordinate plane contain two coordinates, namely the incident angle coordinate and the azimuth coordinate system, the azimuth setting is 0 in the north direction o , clockwise rotation is 360 o The incident angle coordinate system does not distinguish between positive and negative. The incident angle and azimuth information of the gather points in the angle domain gather data are projected into the coordinate plane, and the amplitude data of the depth domain of the gather data is projected into the three-dimensional system according to the z direction of the three-dimensional coordinate system as the depth unit. A profile line is drawn in the set direction from the origin of the three-dimensional coordinate. When the profile line intersects with the azimuth line of the reconstructed center incident angle gather, a two-dimensional gather profile is established along the clockwise direction according to the center incident angle and its range and the azimuth line. Among them, the position of the projection of the central incident angle data point on the three-dimensional coordinate plane is the azimuth line, and the layer data is introduced from the minimum incident angle data channel. Specifically, it refers to projecting the layer data (xj, yj, hj) to the data point (xj, yj, hj) on the minimum incident angle data channel, and automatically tracking according to the reflection amplitude characteristics of the seed point and the search window value parameters to obtain the layer data of the two-dimensional gather section, thereby obtaining the layer data of the reconstructed central incidence angle gather data.

5. The method for calculating crack strength according to claim 1, characterized in that: The S2 step includes the following steps: S21, using the layer data of each center incidence angle gather to calculate the three-component parameter data about color fusion; S22. Reconstruct the color component data values ​​before the color component fusion processing by using the three parameter data values ​​about the color component calculation of each CDP point to obtain three first color component data values ​​of each CDP point.

6. The method for calculating crack strength according to claim 5, characterized in that: In the step S21: The calculation of the first parameter of the color component is specifically as follows: for a certain central incident angle of a certain CDP point, the discrete coefficient is calculated using the depth domain layer data to obtain the discrete coefficient data value of the central incident angle of the CDP; and so on, the discrete coefficient calculation of each central incident angle of the CDP point is completed; the gradient data value of the discrete coefficient obtained for each central incident angle of the CDP point is calculated, so as to obtain the first parameter data value of the CDP point calculated for this type of color component; The calculation of the second parameter of the color component is as follows: Use the depth domain layer data of a certain central incident angle of each CDP point to establish a two-dimensional coordinate system, where the horizontal axis is the angle and the vertical axis is the layer data. o -360 o The azimuth angle and its corresponding layer data are projected in a two-dimensional coordinate system; the relevant intersection data points are fitted with a least squares binary curve to obtain a relevant fitting curve and a functional relationship; the center line is set using the average value of the center incident angle layer data, and the intersection area between the fitting curve and the set center line is calculated; after the intersection area is subjected to relevant mathematical calculations, the calculated result is used as the fitting area of ​​the CDP point; and so on, the calculation of the fitting area of ​​each center incident angle of the CDP point is completed; and the gradient data value of the fitting area obtained for each center incident angle of the CDP point is calculated, so as to obtain the second parameter data value of the CDP point calculated with respect to the type of color component; The calculation of the third parameter of the color component is specifically as follows: the maximum data value is selected using the depth domain layer data of each central incident angle related to each CDP point; and the gradient data value is calculated for the maximum data value of the layer data of a series of central incident angles; and the gradient data value is used as the third parameter data value of the CDP point for this type of color component.

7. The method for calculating crack strength according to claim 6, characterized in that: In the step S22, a calculation formula is reconstructed according to the data values ​​of the relevant color fusion to convert each of the three parameter data values ​​into a first color component data value; The calculation formula for reconstructing the data value of the relevant color fusion is: in, is a parameter data value calculated for a certain color component, The first color component data value calculated for color fusion, =max{ }, =min{ }, [] is the calculation symbol for taking positive integers, and P is a constant.

8. The method for calculating crack strength according to claim 1, characterized in that: The S3 step includes the following steps: S31, using relevant fracture prediction data to classify fracture intensity levels on the target layer plane of the study area, setting relevant color component reconstruction coefficients according to relevant fracture intensity levels, performing data reconstruction processing on three first color components of each CDP point, and obtaining relevant second color components; S32, performing color fusion processing on the three second color reconstruction components of each CDP point in the study area to obtain a color fusion plane map of the crack development intensity.

9. The method for calculating crack strength according to claim 8, characterized in that: In the step S31, the seismic attributes related to the fracture intensity are calculated using the depth domain post-stack seismic data volume and the average data value of the seismic attributes of the target layer segment; the threshold values ​​of the relevant different fracture intensity levels are divided using the fracture intensity data on the well and the average data value of the seismic attributes, and the reconstruction coefficients of the different fracture intensity levels are set; the reconstruction processing on the second color component is performed using the relevant reconstruction coefficient, the fracture intensity level divided by the CDP point on the plane and the data value of the first color component; The reconstruction process of the relevant second color component is as follows: Among them, Aij is the reconstructed data value of the second color component of the jth category of the ith CDP point, Kij is the reconstruction coefficient data value of the jth seismic attribute of the CDP point, Dij is the first color component data value of the CDP and the jth category before reconstruction; n is the number of seismic attributes for calculating fracture strength, which is generally greater than or equal to one, and [] is the calculation symbol for taking positive integers.

10. The method for calculating crack strength according to claim 9, characterized in that: In the step S31, in actual operation, a series of seismic attribute data bodies for fracture strength calculation based on the depth domain post-stack seismic data body are calculated by using a related post-stack fracture calculation method, and the average values ​​of the seismic attribute data of the target layer segment are extracted respectively, and different fracture strength threshold values ​​are divided and the corresponding reconstruction coefficients are set according to the fracture strength division situation on the well, expert experience and reconstruction coefficient setting accuracy; In the step S31, the reconstruction coefficient of a certain seismic attribute of each CDP point is determined, and the reconstruction coefficient value of the seismic attribute of the CDP point is determined according to the seismic attribute data value on the plane of the CDP point, the threshold value divided by the seismic attribute, and the set reconstruction coefficient data value corresponding to the relevant threshold value; in addition, the reconstruction coefficient data value of the seismic attribute is used to reconstruct the three first color components of the CDP point with respect to the color components, so as to obtain the three second color reconstruction components on the CDP point; In the step S31, the three first color components are related to the calculation of the second color component. The seismic attributes used by the three are different. A first color component can have one or more seismic attributes involved in the calculation of the second color component. In the reconstruction processing calculation of the related second color component, since the calculation of a first color component must have one seismic attribute, three depth domain seismic attribute data related to the fracture intensity calculation must be calculated.

Images