Pre-stack gather amplitude correction method and computer storage medium

Abstract

The invention provides a pre-stack gather amplitude correction method and a computer storage medium, and belongs to the field of petroleum and natural gas exploration and development. According to the method, pre-stack gather amplitude correction is carried out based on AVO forward modeling and a standard layer AVA amplitude attenuation trend. According to the method, geological features are fully combined, effective combination of geophysics and geology is achieved, and the requirement for excessive data collection and processing is effectively avoided; the method greatly improves the reliability of the amplitude correction value in a region without well location constraint, and reduces the dependence on the processing data, such as near, middle and far offset coverage times, full coverage times and the like. According to the method, effective combination of well point constraint and standard layer constraint is achieved, and the amplitude correction value of the vast well-free area has a basis.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas exploration and development, and in particular relates to a pre-stack gather amplitude correction method and a computer storage medium. Background Art

[0002] At present, there are many technical methods for amplitude compensation or correction of pre-stack gathers at home and abroad, including correction from the perspective of seismic data processing and correction from the perspective of interpretative processing in the subsequent seismic interpretation process. Regardless of the processing perspective or the interpretation perspective, it is necessary to rely on the forward modeling gathers passing through the well for trend constraints and judgments.

[0003] The amplitude variation with offset (AVO) or amplitude variation with incident angle (AVA) phenomenon is mainly used to estimate the lithology and oil and gas content of the formation. However, in actual situations, the AVO phenomenon is not only affected by the lithology and internal fluid of the underground formation itself, but also by the uneven coverage of the offset. When the two influencing factors are superimposed together, it is impossible to determine the true AVO characteristics in the absence of wells due to the lack of forward gather evidence, and thus it is impossible to determine the near and far polarization amplitude compensation.

[0004] Chinese patent publication CN113589379A discloses a pre-stack gather fidelity amplitude compensation optimization method, which mainly uses the angle and amplitude of the gather itself and the well point AVO forward modeling gather to substitute into the characteristic trinomial of the Zoeppritz equation to obtain a correction function, and continuously corrects the actual gather. Chinese patent publication CN114609672A discloses a pre-stack gather interpretation processing method, system, device and readable storage medium, which mainly determines whether to perform amplitude compensation by judging whether the coverage parameters of the original CRP seismic pre-stack gather are consistent with the full coverage number, and performs amplitude compensation if they are inconsistent. Chinese patent publication CN112462431B discloses a pre-stack gather amplitude compensation method based on well control and offset separation, which mainly uses the original CRP gather within the effective angle range to calculate the intercept A, gradient B and the third coefficient C, and uses the AVO attribute to construct a new CRP gather outside the effective angle range, and then merges the new CRP gather outside the effective angle range with the original CRP gather within the effective angle range to obtain the final gather data. The above three methods all achieve compensation and correction of gather amplitude to a certain extent. The correction parameters of method one can be well compensated for the amplitude at the well point location due to the constraint of the forward modeling gathers of the wells, but the compensation amount cannot be determined at the location without well distribution. Method two compensates from the processing perspective, but the number of coverage of each CRP gather is inconsistent. It is necessary to obtain the number of coverage of each CRP gather at different offsets, which is complicated and computationally expensive, and inefficient. Method three has different effective angles for each CRP gather due to the different number of coverage of each CRP gather. During the operation, the effective angle of each CRP gather must be judged, which makes the actual operation extremely difficult.

[0005] Most of the original pre-stack CRP gather data have low signal-to-noise ratio, unleveled event axis, far-biased stretching distortion, and strong amplitude in the middle and weak at both ends. The first three phenomena can be solved well by means of east denoising, super gather denoising, event leveling, and spectrum balancing, but the relative strength relationship between near, medium and far polarization amplitudes cannot be changed. The phenomenon of strong amplitude in the middle and weak amplitude at both ends is mainly due to the uneven offset coverage caused by the orthogonal acquisition observation system currently used, and the near and far bias coverage times are lower than the middle.

[0006] In recent years, with the deepening of oil and gas exploration and development, reservoir prediction methods based on post-stack seismic data can no longer meet the increasingly complex exploration and development needs, while AVO / AVA technology based on pre-stack gather data has been widely used as a reservoir and fluid prediction method. As the basic data of AVO / AVA technology, the quality of CRP gathers determines the accuracy of reservoir and fluid prediction. There are many simple and effective improvement measures for the problems of low signal-to-noise ratio, unleveled event axis, and far-biased stretching distortion in the original CRP gathers. However, there is a lack of a method that is easy to implement and has good effects in areas without well location constraints for the abnormal AVO phenomenon caused by the difference in near, medium and far-biased coverage times.

[0007] There are currently three main difficulties:

[0008] First, the amplitude compensation amount corresponding to each angle cannot be determined;

[0009] Second, the gathers near the well area can determine the compensation amount through “one-hole view”, but the amplitude compensation cannot be effectively quality controlled in the whole area;

[0010] Third, the compensation method is too complicated and requires obtaining the near, middle and far coverage times of each CRP gather position, which is not efficient.

[0011] These difficulties restrict the amplitude recovery of prestack CRP gathers, which in turn affects the reliability of prestack reservoir prediction and oil and gas detection. Summary of the invention

[0012] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art, and to provide a pre-stack gather amplitude correction method and a computer storage medium, which utilizes the comprehensive amplitude attenuation trend of the AVO standard layer in the whole area to perform angle-based quantitative amplitude correction on the CRP gather.

[0013] The present invention is achieved through the following technical solutions:

[0014] A first aspect of the present invention provides a method for amplitude correction of pre-stack gathers. The method performs amplitude correction of pre-stack gathers based on AVO forward modeling and AVA amplitude attenuation trend of a standard layer.

[0015] Preferably, the method comprises:

[0016] The first step is to analyze and process the original gathers;

[0017] Step 2: AVO standard well selection;

[0018] Step 3: AVO standard layer selection;

[0019] Step 4: Single well AVO forward modeling and comprehensive trend extraction, and determine whether the trends are similar. If so, the AVO standard layer selection is determined to be reasonable, and the comprehensive trend factor of the standard layer is obtained, and then the fifth step is turned to. If not, the AVO standard layer selection is determined to be unreasonable, and then return to the third step;

[0020] Step 5: Use the comprehensive trend factor of the standard layer to perform amplitude correction and obtain the correction result;

[0021] Step 6: Determine whether the calibration result meets the requirements. If yes, proceed to step 7; if no, return to step 2;

[0022] Step 7: Conduct pre-stack reservoir prediction.

[0023] Preferably, the second step includes:

[0024] Wells that meet the following conditions are selected as AVO standard wells:

[0025] Condition 1: Located in a tectonic stable area;

[0026] Condition 2: Stay away from fractures;

[0027] Condition 3: The longitudinal and transverse wave curves are complete;

[0028] Condition 4: Drill through the target layer and the AVO standard layer at the same time.

[0029] Preferably, the operation of the third step includes:

[0030] The strata with stable regional sedimentation and no reservoir development were selected as the AVO standard layers.

[0031] Preferably, the fourth step includes:

[0032] AVO forward modeling is carried out for each AVO standard well in turn. A time window is selected near the AVO standard layer of the forward modeling gather, and linear fitting of the root mean square amplitude change trend is carried out to obtain the linear fitting gradient. It is judged whether the trends are similar. If so, the AVO standard layer selection is judged to be reasonable, and the arithmetic mean of the linear fitting gradients of all AVO standard wells is taken as the comprehensive trend factor of the standard layer, and then the fifth step is entered; if not, the AVO standard layer selection is judged to be unreasonable, and then the third step is returned.

[0033] Preferably, the operation of selecting a time window near the AVO standard layer of the forward modeling gather and performing linear fitting of the root mean square amplitude variation trend to obtain a linear fitting gradient includes:

[0034] A time window of 10 ms above and below the AVO standard layer is selected, the root mean square of the amplitude is extracted to obtain the root mean square amplitude, and then a linear fitting formula is used to perform linear fitting to obtain the linear fitting gradient.

[0035] Preferably, the operation of determining whether the trends are similar includes:

[0036] It is determined whether the linear fitting gradients of all AVO standard wells are positive and concentrated near the constant C. If so, it is determined that the trends are similar; if not, it is determined that the trends are not similar.

[0037] Preferably, the fifth step includes:

[0038] The linear fitting gradient of each common-incident angle gather is set to the comprehensive trend factor of the standard layer, and then the root mean square amplitude, i.e. the correction result, is calculated using the linear fitting formula.

[0039] Preferably, the operation of determining whether the calibration result meets the requirements in the sixth step includes:

[0040] Perform AVO forward modeling on the reservoir section of the standard well to obtain the AVO forward modeling gathers, and obtain the intercept and gradient of the AVO forward modeling gather fitting, and also obtain the intercept and gradient of the corrected well-passing gather fitting;

[0041] If the intercept of the AVO forward gather fitting and the intercept of the corrected through-well gather fitting are both positive or negative, and the gradient of the AVO forward gather fitting and the gradient of the corrected through-well gather fitting are both positive or negative, and the stacked sections of the near, middle and far parts show the characteristics of strong-medium-strong-weak, then it is judged that the correction result meets the requirements.

[0042] According to a second aspect of the present invention, a computer-readable storage medium is provided, wherein 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 a pre-stack trace gather amplitude correction method of the present invention.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The method of the present invention fully combines geological characteristics, achieves an effective combination of geophysics and geology, and effectively avoids the need for excessive data acquisition and processing; greatly improves the reliability of amplitude correction in areas without well location constraints, and reduces the dependence on processing data such as near, medium and far deviation coverage times, full coverage times, etc.;

[0045] (2) The method of the present invention achieves an effective combination of well point constraints and standard layer constraints, so that the amplitude correction value in the vast well-free area has a basis to follow. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a flowchart of the steps of the method of the present invention;

[0047] Figure 2This is a diagram of the common original CRP gather amplitude "weak-strong-weak" phenomenon and the number of coverages;

[0048] Figure 3 The actual gathers and single well AVO standard layer selection and the RMS amplitude variation with offset distance;

[0049] Figure 4 The amplitude trend analysis and linear analysis diagram of the six AVO standard wells in the study area in the standard layer of the Longtan Formation;

[0050] Figure 5 Comparative analysis and quality control diagrams of the gathers before and after correction and the forward modeling gathers for the two verification wells in the study area;

[0051] Figure 6 Comparison of angle stacked sections before and after correction for the study area;

[0052] Figure 7 Prestack density inversion profile and layer-by-layer plan view before (left) and after (right) gather correction in a shale gas work area in the Sichuan Basin. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0054] The present invention provides a pre-stack gather amplitude correction method, which performs pre-stack gather amplitude correction based on AVO forward modeling and standard layer AVA amplitude attenuation trend. The present invention utilizes the comprehensive trend of the AVO standard layer to constrain the amplitude compensation of the full-area CRP gather at different incident angles, thereby obtaining high-fidelity pre-stack gather data.

[0055] The present invention greatly improves the reliability of amplitude correction in areas without well location constraints, while reducing the dependence on processing data such as near, medium and far deviation coverage times, full coverage times, etc., fully utilizing geological stratigraphic characteristics, and providing a method for rapid pre-stack gather amplitude correction with standards and quality control, laying a good data foundation for subsequent pre-stack reservoir prediction.

[0056] like Figure 1 As shown, the method of the present invention comprises:

[0057] The present invention provides a pre-stack gather amplitude correction method, which performs pre-stack gather amplitude correction based on AVO forward modeling and standard layer AVA amplitude attenuation trend. The present invention utilizes the comprehensive trend of the AVO standard layer to constrain the amplitude compensation of the full-area CRP gather at different incident angles, thereby obtaining high-fidelity pre-stack gather data.

[0058] The present invention greatly improves the reliability of amplitude correction in areas without well location constraints, while reducing the dependence on processing data such as near, medium and far deviation coverage times, full coverage times, etc., fully utilizing geological stratigraphic characteristics, and providing a method for rapid pre-stack gather amplitude correction with standards and quality control, laying a good data foundation for subsequent pre-stack reservoir prediction.

[0059] like Figure 1 As shown, the method of the present invention comprises:

[0060] The first step is to analyze and process the original gathers;

[0061] Step 2: AVO standard well selection;

[0062] Step 3: AVO standard layer selection;

[0063] Step 4: Single well AVO forward modeling and comprehensive trend extraction, and determine whether the trends are similar. If so, the standard layer selection is determined to be reasonable, and the comprehensive trend factor of the standard layer is obtained, and then the fifth step is turned to. If not, the standard layer selection is determined to be unreasonable, and then return to the third step;

[0064] Step 5: Use the comprehensive trend factor of the standard layer to perform amplitude correction and obtain the correction result;

[0065] Step 6: Determine whether the calibration result is reasonable. If yes, proceed to step 7; if no, return to step 2;

[0066] Step 7: Conduct pre-stack reservoir prediction: Conduct pre-stack reservoir prediction based on the corrected CIP gathers.

[0067] Embodiment 1:

[0068] The first step includes:

[0069] In the early stage of implementation, analysis work was carried out on the collected original CRP gathers, including: analysis of the acquisition observation system and analysis of the change of single-channel amplitude at different positions with offset distance. Through analysis, it was determined whether the amplitude was affected by the acquisition observation system to produce abnormal AVO phenomenon. Then, routine processing work was carried out based on the gather analysis results, including but not limited to Radon denoising, event layer flattening and spectral balancing, to obtain the common reflection point gather CRP_1, and then the common reflection point gather CRP_1 was converted into a common incidence angle gather CIP_1 by angle gather conversion. The first step is implemented using existing technologies and will not be repeated here.

[0070] Embodiment 2:

[0071] The second step includes:

[0072] Wells that meet the following conditions are selected as AVO standard wells:

[0073] Condition 1: Located in a tectonic stable area;

[0074] Condition 2: Stay away from fractures;

[0075] Condition 3: The longitudinal and transverse wave curves are complete;

[0076] Condition 4: Drill through the target layer and the AVO standard layer at the same time.

[0077] Taking the wells that meet the above four conditions as AVO standard wells can avoid the mismatch between wells and seismic data caused by inaccurate imaging of the fault.

[0078] Embodiment 3:

[0079] The third step includes:

[0080] The strata with stable regional sedimentation and no reservoir development are selected as the AVO standard layers, such as the Permian Longtan Formation and the Ordovician Wufeng Formation in the Sichuan Basin. When there is no reservoir development and no fluid in the strata, its AVO response is only affected by the absorption of seismic wave energy by the strata. The longer the propagation distance, the greater the energy attenuation, showing the characteristic that the amplitude decreases with the increase of offset distance.

[0081] Embodiment 4:

[0082] The fourth step includes:

[0083] AVO forward modeling is carried out for each AVO standard well based on the existing P-wave and S-wave logging data. A time window is selected near the AVO standard layer of the forward modeling gather, and linear fitting of the root mean square amplitude change trend is carried out to obtain the linear fitting gradient (i.e., the gather amplitude attenuation factor). It is judged whether the trends are similar. If so, the AVO standard layer is judged to be selected reasonably, and the arithmetic mean of the linear fitting gradients of all AVO standard wells is calculated to obtain the average attenuation factor. The average attenuation factor is used as the trend factor of the entire standard layer in the region (i.e., the arithmetic mean of the linear fitting gradients of all AVO standard wells is used as the comprehensive trend factor of the standard layer), i.e., the comprehensive trend factor of the standard layer. The comprehensive trend factor of the standard layer can be used for subsequent energy compensation and correction work. At this time, the comprehensive trend is obtained, and then the fifth step is entered; if not, the AVO standard layer is judged to be unreasonable, and then the third step is returned.

[0084] Specifically, a time window is selected near the AVO standard layer of the forward modeling gather, and the linear fitting of the root mean square amplitude change trend is carried out to obtain the linear fitting gradient. The operation includes: according to the standard layer interpretation layer, a time window of 10ms above and below the AVO standard layer is selected, the root mean square (RMS) of the amplitude is extracted to obtain the root mean square amplitude, and then the linear fitting of the root mean square amplitude with the incident angle is carried out. The linear fitting formula is: Amp (rms) =A*Angle+B, where Amp(rms) represents the root mean square amplitude, A represents the linear fitting gradient (the linear fitting gradients obtained by fitting each common incident angle gather are: A1, A2, A3 to An), and B represents the intercept, which is the average value of the root mean square amplitude of the standard well at 0° incidence angle.

[0085] Specifically, the operations to determine whether the trends are similar include:

[0086] Determine whether the linear fitting gradients of all AVO standard wells are positive and concentrated near a constant C (that is, all fitting curves have a decay trend and the decay factor is stable, that is, the trends are similar). If so, the trends are determined to be similar; if not, the trends are determined to be dissimilar.

[0087] Embodiment 5:

[0088] The fifth step is the amplitude correction based on the comprehensive trend, that is, the trend AVO correction. The operations of the fifth step include:

[0089] Taking the comprehensive trend factor of the standard layer as a constraint, under the control of the time window, the AVO correction of the standard layer gathers in the whole area is carried out, and the correction results are obtained as follows:

[0090] In the fifth step, the linear fitting gradient of each common incidence angle gather is set to the standard layer comprehensive trend factor, and then the linear fitting formula (Amp (rms) =A*Angle+B) to calculate the root mean square amplitude, i.e. the correction result. Thus, the AVO characteristics of the corrected gather are closer to the standard layer trend, and the gather correction is more refined. While the amplitude of the standard layer of the actual gather is corrected, the amplitude of the target reservoir section is also corrected accordingly. The root mean square amplitude corresponding to each angle will change, and the reservoir AVO characteristics will be restored to the real response.

[0091] Embodiment 6:

[0092] The sixth step is to carry out quality control on the calibration results to ensure the reliability of the calibration results.

[0093] The operations to determine whether the calibration results meet the requirements include:

[0094] Perform AVO forward modeling on the reservoir section of the standard well to obtain the AVO forward modeling gathers, and obtain the intercept and gradient of the AVO forward modeling gathers, and at the same time obtain the intercept and gradient of the corrected through-well gathers (the through-well gathers refer to the corrected gathers at the well location coordinates);

[0095] If the intercept of the AVO forward gather fitting and the intercept of the corrected through-well gather fitting are both positive or negative, and the gradient of the AVO forward gather fitting and the gradient of the corrected through-well gather fitting are both positive or negative, and the stacked profiles of the near, middle and far parts (the profiles are obtained by performing small-angle stacking, medium-angle stacking and large-angle stacking using the corrected gathers) show the characteristics of strong-medium-strong-weak, then it is judged that the correction result meets the requirements.

[0096] After targeted denoising and event layer flattening processing were carried out on prestack gathers in a certain study area in Sichuan, the gather quality was significantly improved, and the corresponding signal-to-noise ratio was improved. AVO analysis was carried out on multiple through-well gathers in the study area. The amplitude of the target layer Wufeng-Longmaxi Formation has an overall "weak-strong-weak" abnormal AVO response feature, such as Figure 2 As shown. After analysis, the overall AVO abnormal characteristics of the target layer are mainly caused by uneven offset coverage and complex structure. Through comprehensive analysis of stratigraphic geological characteristics, the Longtan Formation in the study area is selected as the AVO standard layer. The structure in the area is complex, and 6 wells such as NY1, which are far away from the fault, drill through the AVO standard layer Longtan Formation and the target layer Wufeng-Longmaxi Formation at the same time, and have complete P- and S-wave logging curves, are selected as AVO standard wells.

[0097] AVO forward modeling based on vertical and horizontal density curves was carried out on the selected 6 AVO standard wells, and the forward modeling gathers were used to analyze the Longtan Formation of the AVO standard layer. The analysis shows that the forward modeling gathers of the 6 AVO standard wells have a strong influence on the root mean square amplitude (e.g. Figure 3 As shown in Figure 2, the attenuation factor gradually decays with the increase of the incident angle, and the attenuation factor distribution is relatively stable, ranging from 0.019 to 0.022 (as shown in Figure 2). Figure 4 The results show that the selection of the AVO standard layer of the Longtan Formation is reasonable. Finally, based on the linear fitting relationship of the six standard wells, the comprehensive attenuation factor of the AVO standard layer in this area is calculated to be -0.021, and the comprehensive attenuation trend is Amp (RMS) =0.058-0.021*Angle. With the comprehensive trend as the constraint, background correction is performed. The proportional factors corresponding to each angle of each gather are different, as shown in Table 1, and the correction is more refined. Comparison of the target layer Wufeng-Longmaxi Formation before and after gather correction (such as Figure 5 As shown in Figure 2, the energy relationship of the near, middle and far sections was corrected from "weak-strong-weak" to a more reasonable "strong-middle-weak" (as shown in Figure 2). Figure 6 The quality control of AVO trend correction was verified to be rational and stable.

[0098]

[0099] Table 1

[0100] From the density inversion profile (such as Figure 7As shown in Figure 2, before correction, the AVO type of the gather was variable and the attenuation trend was unstable. The low-density value (warm color) of the shale changed rapidly and showed an unstable distribution, which obviously did not conform to the characteristics of stable shale deposition. After correction, the low-density value was stably distributed at the bottom of the Wufeng Formation, which better reflected the distribution law of shale. From a plane perspective, the low-density warm-colored area after correction showed a large-scale stable distribution (as shown in Figure 2). Figure 6 The results of pre-stack density inversion based on the AVO-corrected gathers are consistent with the depositional law of semi-deep-water to deep-water shelf facies of shale in this area. The prediction of the main geological sweet spots in the whole area is realized. Combined with the comprehensive evaluation of engineering sweet spots and burial depth, breakthroughs in the two wells SY5-1 and SY5-2 are achieved in the southern part of the study area, verifying the effectiveness of the present invention.

[0101] The present invention makes full use of the geological characteristics of the formation, achieves an effective combination of geology and geophysics, greatly improves the reliability of the amplitude correction in areas without well location constraints, and reduces the dependence on processing data such as near, medium and far deviation coverage times, full coverage times, etc., forming a fast, efficient and targeted pre-stack gather amplitude correction method, which greatly improves the accuracy of subsequent pre-stack reservoir prediction results.

[0102] The present invention adds an effective means of pre-stack gather amplitude correction. It is a fast, efficient and targeted pre-stack gather amplitude correction method, which greatly improves the fidelity of pre-stack gathers, lays a data foundation for subsequent pre-stack reservoir prediction and pre-stack oil and gas detection, and is meaningful for oil and gas reservoir exploration and development.

[0103] 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 pre-stack gather amplitude correction method, characterized by: The method performs pre-stack gather amplitude correction based on AVO forward modeling and standard layer AVA amplitude attenuation trend.

2. The pre-stack gather amplitude correction method according to claim 1, characterized in that: The method comprises: The first step is to analyze and process the original gathers; Step 2: AVO standard well selection; Step 3: AVO standard layer selection; Step 4: Single well AVO forward modeling and comprehensive trend extraction, and determine whether the trends are similar. If so, the AVO standard layer selection is determined to be reasonable, and the comprehensive trend factor of the standard layer is obtained, and then the fifth step is turned to. If not, the AVO standard layer selection is determined to be unreasonable, and then return to the third step; Step 5: Use the comprehensive trend factor of the standard layer to perform amplitude correction and obtain the correction result; Step 6: Determine whether the calibration result meets the requirements. If yes, proceed to step 7; if no, return to step 2; Step 7: Conduct pre-stack reservoir prediction.

3. The pre-stack gather amplitude correction method according to claim 2, characterized in that: The second step includes: Wells that meet the following conditions are selected as AVO standard wells: Condition 1: Located in a tectonic stable area; Condition 2: Stay away from fractures; Condition 3: The longitudinal and transverse wave curves are complete; Condition 4: Drill through the target layer and the AVO standard layer at the same time.

4. The pre-stack gather amplitude correction method according to claim 2, characterized in that: The third step includes: The strata with stable regional sedimentation and no reservoir development were selected as the AVO standard layers.

5. The pre-stack gather amplitude correction method according to claim 2, characterized in that: The fourth step includes: AVO forward modeling is carried out for each AVO standard well in turn. A time window is selected near the AVO standard layer of the forward modeling gather, and linear fitting of the root mean square amplitude change trend is carried out to obtain the linear fitting gradient. It is judged whether the trends are similar. If so, the AVO standard layer selection is judged to be reasonable, and the arithmetic mean of the linear fitting gradients of all AVO standard wells is taken as the comprehensive trend factor of the standard layer, and then the fifth step is entered; if not, the AVO standard layer selection is judged to be unreasonable, and then the third step is returned.

6. The pre-stack gather amplitude correction method according to claim 5, characterized in that: The operations of selecting a time window near the AVO standard layer of the forward modeling gather and performing linear fitting of the root mean square amplitude variation trend to obtain the linear fitting gradient include: A time window of 10 ms above and below the AVO standard layer is selected, the root mean square of the amplitude is extracted to obtain the root mean square amplitude, and then a linear fitting formula is used to perform linear fitting to obtain the linear fitting gradient.

7. The pre-stack gather amplitude correction method according to claim 5, characterized in that: The operations to determine whether the trends are similar include: It is determined whether the linear fitting gradients of all AVO standard wells are positive and concentrated near the constant C. If so, it is determined that the trends are similar; if not, it is determined that the trends are not similar.

8. The pre-stack gather amplitude correction method according to claim 2, characterized in that: The fifth step includes: The linear fitting gradient of each common-incident angle gather is set to the comprehensive trend factor of the standard layer, and then the root mean square amplitude, i.e. the correction result, is calculated using the linear fitting formula.

9. The pre-stack gather amplitude correction method according to claim 2, characterized in that: The operations in step 6 to determine whether the calibration results meet the requirements include: Perform AVO forward modeling on the reservoir section of the standard well to obtain the AVO forward modeling gathers, and obtain the intercept and gradient of the AVO forward modeling gather fitting, and also obtain the intercept and gradient of the corrected well-passing gather fitting; If the intercept of the AVO forward gather fitting and the intercept of the corrected through-well gather fitting are both positive or negative, and the gradient of the AVO forward gather fitting and the gradient of the corrected through-well gather fitting are both positive or negative, and the stacked sections of the near, middle and far parts show the characteristics of strong-medium-strong-weak, then it is judged that the correction result meets the requirements.

10. 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 in the pre-stack gather amplitude correction method according to any one of claims 1 to 9.

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