Method and apparatus for characterizing near-surface seismic parameters in desert areas

Abstract

The present invention provides a method and device for characterizing near-surface seismic parameters in desert areas. The method includes: dividing the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table in the desert area; establishing a characteristic function for the upper part and a characteristic function for the lower part, wherein the upper part is a non-linear continuous medium structure and the lower part is a layered medium structure; establishing a Q-field characterization function for the desert area according to the characteristic function of the upper part and the characteristic function of the lower part. The present invention realizes the detection of the near-surface structure and the characterization of the characteristic function in the desert area in a way of step-by-step longitudinally and regionally and spatially horizontally, which is beneficial to the accurate characterization of the formation parameters of the near-surface structure in the desert area, effectively improves the accuracy of near-surface structure detection and characterization; and greatly improves the establishment accuracy of the surface Q-field in the desert area, laying a solid foundation for further broadening the frequency band width of seismic data in the desert area and effectively improving the success rate of fine interpretation of geological target bodies and oil and gas prediction.

Description

Technical Field

[0001] The present invention relates to the field of petroleum exploration, in particular to the field of near-surface formation parameter investigation methods, and in particular to a near-surface earthquake parameter characterization method and device in desert areas. Background Art

[0002] Understandably, seismic exploration near-surface stratum parameter surveys typically involve investigating characteristic parameters such as thickness, velocity, density, absorption attenuation coefficient, and Poisson's ratio. This involves studying the surface structural characteristics, longitudinal and lateral variations, and their impact on seismic waves, in order to mitigate, circumvent, overcome, or eliminate the adverse effects of near-surface strata on seismic exploration. Because near-surface structural characteristics often vary significantly across different surface regions, the results of near-surface structural stratum parameter surveys vary significantly, particularly in areas with complex near-surface structures, such as those with dramatic surface fluctuations, areas with drastic surface structural changes, and deserts.

[0003] Western my country is home to vast desert areas, such as those in the Tarim and Junggar oil and gas basins. These dunes are characterized by large undulations, diverse types, rapid changes in vertical and horizontal spatial structure, thick quicksand layers, and complex structures. These characteristics create world-class geophysical exploration methodological challenges, including severe scattering noise in seismic data, strong absorption and attenuation of high-frequency signals, and severe and drastically changing absorption and attenuation of near-surface structures. Therefore, characterizing the characteristic functions and parameters of near-surface structures in desert areas, as well as detecting and compensating for absorption and attenuation parameters, will directly impact the signal reception and recovery, fidelity processing, and precise imaging of seismic data, and are of great significance for improving the accuracy of seismic data inversion and the success rate of oil and gas prediction.

[0004] Furthermore, in the vast, undulating, and scattered desert landscape, facing the challenge (demand) of accurately depicting or characterizing the characteristic parameters of all points on each dune (sand ridge), a detailed analysis of the near-surface structure of each (type) of dune (sand ridge) is conducted based on a macroscopic analysis. The complexity of the method is presented in the following two aspects:

[0005] ① The complexity of the surface structural characteristics of sand dunes (sand ridges) in the desert area in the vertical direction.

[0006] According to recent research, the longitudinal structure of aeolian dunes in the desert area of the Tarim Basin shows different variation characteristics. Overall, from top to bottom, it presents the structural characteristics of a two-phase or multi-phase medium such as a non-linear continuous medium and a layered medium. Taking the water table as the interface, the dunes above it show the characteristics of a non-linear continuous medium, with fluidity on the plane along the regional monsoon direction, large undulations, being relatively loose, having a certain compaction change from top to bottom, severe absorption attenuation, and rapid and difficult-to-accurately obtain changes in characteristic parameters; below the water table is the structural characteristic of a layered medium with a relatively stable planar distribution, including water-bearing fine sand, weathered layer, clay layer or diagenetic strata, etc., with very small changes in intra-layer parameters and relatively small absorption attenuation compared to the low-velocity zone dunes overlying the water table;

[0007] ② Complexity of the spatial distribution of dunes in the transverse direction

[0008] There are significant differences in different parts of the same dune (such as the windward side and the leeward side, the main body part and the wing part), with large differences in the looseness and compaction of sand grains, etc.; the variation laws of honeycomb dunes and longitudinal dunes are different; there are large differences in lithology, thickness and compaction between the flat area and the dunes. In the transverse direction, different types and different sedimentary systems are combined with each other, with large changes in thickness, differential compaction, absorption parameters, etc., which brings great difficulties to the surface structure characterization, characteristic parameter detection and reliable extraction of various dunes in the desert area.

[0009] In existing methods, the near-surface structure investigation method in the desert area takes the layered medium theory as the theoretical basis for near-surface structure characterization, and uses the characteristic parameter detection and characterization methods of the layered medium surface structure to carry out research on the near-surface structure detection and parameter characterization methods in the desert area. There has not been a special study on the characteristic parameters of the near-surface two-phase or multi-phase medium structure in the desert area. The characteristic parameters of the near-surface structure with different characteristics and different sedimentary systems are all characterized by the method of uniform layered medium. The extraction methods of the near-surface structure absorption attenuation parameters in the desert area all use the structural characteristics of a single medium (uniform layered medium) to characterize. It not only does not consider the influence of the complex structure characteristics such as two-phase or multi-phase media in the desert area on the detection and characterization of near-surface structure characteristic functions and parameters, but also does not consider the influence of the overlying dunes on the accuracy of obtaining the Q value of the underlying layered medium below the water table. The Q value is directly extracted from the seismic record without eliminating the influence of the dunes, and then calibrated with the Q value calculated at the surface parameter survey points, and the accuracy of the established Q field is low. Due to many reasons such as the understanding of dune characteristics, the description of the spatial variation law of absorption attenuation parameters, and the establishment of a one-time Q field, the accuracy of establishing the near-surface absorption attenuation Q field in the desert area is low, and the absorption attenuation compensation effect is not ideal. There are specifically the following three problems:

[0010] 1) The single layered medium structure characterization method is difficult to accurately characterize the two-phase or multi-phase medium structure characteristics of the near-surface structure in the desert area in the longitudinal direction:

[0011] ①It is difficult for a single structural characterization method to accurately characterize the longitudinal structural characteristic parameters of desert dual-phase or multi-phase media

[0012] ②It is difficult to characterize the structural characteristic function of the non-linear continuous medium in the low velocity reduction layer above the water table

[0013] ③The characterization accuracy of the structural characteristic function of the high velocity layer below the water table is greatly affected by the overlying strata

[0014] For the huge differences in the structural characteristics above and below the water table, the previous method of characterizing homogeneous layered media is obviously not accurate enough, and large calculation errors will inevitably occur

[0015] 2) The single layered medium structural characterization method is difficult to accurately characterize the complex and variable lateral characteristics of the near-surface dual-phase or multi-phase media structure in the desert area:

[0016] ①It is difficult for a single structural characteristic method to accurately characterize the lateral structural characteristic parameters of desert dual-phase or multi-phase media

[0017] ②It is difficult to characterize the spatial characteristic function of the non-linear continuous medium in the low velocity reduction zone above the water table

[0018] ③The spatial characterization accuracy of the structural characteristic function of the high velocity layer below the water table is greatly affected by the overlying strata

[0019] The high velocity layer and the low velocity reduction layer show different regional variation characteristics in the lateral direction. The previous method of characterizing the high velocity layer characteristic function of single layered homogeneous media has large errors in space and shows complex and variable zoning characteristics. The constructed characteristic parameter field will inevitably produce large calculation errors, which is not conducive to eliminating the influence of the near-surface in the desert area on seismic data

[0020] 3) There are many influencing factors and low accuracy in constructing the near-surface absorption attenuation parameter field in the desert area by one-step method:

[0021] At present, the relatively common method for detecting and characterizing near-surface absorption attenuation parameters is to comprehensively construct the near-surface Q field through the first arrival wave analysis of large gun seismic records constrained by micro-logging, that is, the one-time surface Q field construction method; this method has formed a highly mature method and software system, which has been widely used and has outstanding effects in the eastern region of China, and is relatively widely used in the desert area of the western region of China. However, in the desert area with undulating and scattered spatial distribution, the one-time Q field construction method has the following five problems

[0022] ①It is difficult to accurately construct the Q field characterization of the near-surface dual-phase media structure in the desert area by one-step method

[0023] ②The high-frequency changes in the desert area in space are difficult to meet the assumption conditions of the one-step method for constructing the near-surface Q field

[0024] From the single-shot seismic records in the desert area (as shown in Figure 1 ), it can be seen that the influence of sand dunes is very serious, and there are very large differences in information such as the travel time, amplitude, frequency, and energy of seismic waves. This not only affects the picking of the first arrival waves in seismic records but also seriously affects the calculation accuracy of the near-surface Q value.

[0025] ③ The spatial high-frequency variation of the first arrival wave information in the desert area seismic records affects the accuracy of site construction.

[0026] ④ The Q-field construction error caused by the drastic spatial variation in the low-velocity layer in the desert area is superimposed on the high-velocity layer.

[0027] ⑤ Surface survey points such as micro-logging are difficult to effectively constrain the drastic spatial variation in the low-velocity layer in the desert area.

[0028] The one-step construction of the near-surface absorption attenuation parameter field in the desert area is affected by many factors such as the two-phase or multi-phase medium structure characteristics of the near-surface structure in the desert area, the low-velocity layer that presents zonal characteristics in space and is difficult to accurately characterize with high-frequency drastic changes, and the surface survey point results that are difficult to effectively achieve spatial constraints. It is difficult to accurately and precisely construct the near-surface structure absorption attenuation parameter field in the desert area, resulting in large spatial errors and affecting the correction processing effect. Summary of the Invention

[0029] Aiming at the problems in the existing methods, the near-surface seismic parameter characterization method and device provided by the present invention realize the detection of the near-surface structure and the characterization of the characteristic function in the desert area in a vertical step-by-step and horizontal sub-region and sub-space manner, which is conducive to accurately depicting the formation parameters of the near-surface structure in the desert area and effectively improving the accuracy of near-surface structure detection and characterization; and greatly improves the establishment accuracy of the surface Q field in the desert area, laying a solid foundation for further broadening the frequency band width of seismic data in the desert area and effectively improving the success rate of fine interpretation of geological target bodies and oil and gas prediction.

[0030] To solve the above method problems, the present invention provides the following method solutions:

[0031] In the first aspect, the present invention provides a near-surface seismic parameter characterization method for desert areas, including:

[0032] Dividing the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table in the desert area;

[0033] Establishing the characteristic function of the upper part and the characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure;

[0034] Establishing the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part.

[0035] In one embodiment, establishing the characteristic function of the upper part includes:

[0036] Classify the upper part to generate multiple dune type partitions;

[0037] Obtain the representation function of each partition in the multiple dune type partitions;

[0038] Establish the surface structure model of the control points of the upper part;

[0039] Taking point control as a constraint condition, establish the characteristic parameter field of each partition according to the representation function;

[0040] Generate the characteristic function of the upper part according to the model and the characteristic parameter field.

[0041] In one embodiment, establishing the characteristic function of the upper part further includes:

[0042] Perform characteristic parameter influence correction on the characteristic parameter field to generate a corrected seismic record.

[0043] In one embodiment, establishing the characteristic function of the lower part includes:

[0044] Generate the layered medium model of the lower part according to the seismic record and the layered medium structure;

[0045] Use the first arrival refraction tomography method and / or the first arrival refraction energy attenuation analysis method to obtain the characteristic parameter field of the layered medium model;

[0046] Establish the characteristic function of the lower part according to the characteristic parameter field.

[0047] In one embodiment, establishing the Q-field representation function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part includes:

[0048] Establish the Q-field of the upper part according to the characteristic function of the upper part;

[0049] Establish the Q-field of the lower part according to the characteristic function of the lower part;

[0050] Fuse the Q-field of the upper part and the Q-field of the lower part to generate the near-surface Q-field of the desert area.

[0051] In a second aspect, the present invention provides a near-surface seismic parameter characterization device for a desert area, and the device includes:

[0052] A longitudinal distribution unit for dividing the desert area into an upper part and a lower part from top to bottom according to the water table of the desert area determined in advance;

[0053] A feature function building unit for building the feature function of the upper part and the feature function of the lower part, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure;

[0054] A Q-field characterization unit for building the Q-field characterization function of the desert area according to the feature function of the upper part and the feature function of the lower part.

[0055] In one embodiment, the feature function building unit includes:

[0056] A dune classification module for classifying the upper part to generate multiple dune type partitions;

[0057] A characterization function calculation module for calculating the characterization function of each partition in the multiple dune type partitions;

[0058] A model building module for building the surface structure model of the control points of the upper part;

[0059] A partition parameter field building module for building the characteristic parameter field of each partition based on the characterization function with point control as the constraint condition;

[0060] An upper part feature function generation module for generating the feature function of the upper part according to the model and the characteristic parameter field.

[0061] In one embodiment, the feature function building unit further includes:

[0062] An earthquake record generation module for correcting the influence of characteristic parameters on the characteristic parameter field to generate a corrected earthquake record.

[0063] In one embodiment, the feature function building unit further includes:

[0064] A layered model generation module for generating the layered medium model of the lower part according to the earthquake record and the layered medium structure;

[0065] A layered parameter field calculation module for calculating the characteristic parameter field of the layered medium model by using the first arrival refraction tomography method and / or the first arrival refraction energy attenuation analysis method;

[0066] A lower part feature function building module for building the feature function of the lower part according to the characteristic parameter field.

[0067] In one embodiment, the Q-field characterization unit includes:

[0068] An upper part Q-field building module for building the Q-field of the upper part according to the feature function of the upper part;

[0069] Lower Q-field establishment module, configured to establish the Q-field of the lower part according to the characteristic function of the lower part;

[0070] Q-field characterization function generation module, configured to generate the near-surface Q-field of the desert area by fusing the Q-field of the upper part and the Q-field of the lower part.

[0071] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for characterizing near-surface seismic parameters in a desert area are implemented.

[0072] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for characterizing near-surface seismic parameters in a desert area are implemented.

[0073] As can be seen from the above description, the method and device for characterizing near-surface seismic parameters in a desert area provided by the embodiments of the present invention first divide the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table of the desert area; then, establish the characteristic function of the upper part and the characteristic function of the lower part, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure; finally, establish the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part. Based on in-depth research and analysis of the near-surface structure characteristics of the desert area, the present invention provides a step-by-step characterization method for the near-surface structure characteristics of the desert area, solves a series of problems such as the accurate characterization of the complex variation characteristics of the near-surface structure characteristic function and parameter space in the desert area and the construction of a high-precision near-surface structure parameter field in the desert area, realizes the fine characterization of the near-surface structure characteristics of the desert area, better eliminates the influence of the near-surface in the desert area on seismic data, reduces the data acquisition cost, effectively improves the resolution and accuracy of seismic data, so as to achieve the purpose of enhancing the service oil and gas exploration ability. Description of the Drawings

[0074] In order to more clearly illustrate the method solutions in the embodiments of the present invention or the existing methods, the following will briefly introduce the drawings required for the description of the embodiments or the existing methods. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0075] Figure 1 It is a schematic diagram of a single-shot seismic record in a certain desert area in the background method of the present invention;

[0076] Figure 2 It is a schematic flowchart of the method for characterizing near-surface seismic parameters in a desert area in the embodiments of the present invention;

[0077] Figure 3 Schematic flow of step 200 in the embodiment of the present invention Figure 1 ;

[0078] Figure 4 Schematic flow of step 200 in the embodiment of the present invention Figure 2 ;

[0079] Figure 5 Schematic flow of step 200 in the embodiment of the present invention Figure 3 ;

[0080] Figure 6 Schematic flow chart of step 300 in the embodiment of the present invention;

[0081] Figure 7 Schematic flow chart of the method for characterizing near-surface seismic parameters in desert areas in a specific application example of the present invention;

[0082] Figure 8 Method roadmap for establishing near-surface characteristic parameter field and impact correction in desert areas in a specific application example of the present invention;

[0083] Figure 9 Schematic diagram of near-surface stratigraphic structure in desert areas in a specific application example of the present invention;

[0084] Figure 10 Schematic diagram of time-depth relationship of a micro-logging point in desert areas in a specific application example of the present invention;

[0085] Figure 11 Flow chart of the method for characterizing and correcting near-surface characteristic parameters in desert areas in a specific application example of the present invention;

[0086] Figure 12 Relationship diagram between Q value and velocity of high-velocity layer in a specific application example of the present invention;

[0087] Figure 13 Relationship diagram between Q value of high-velocity layer and sand participation in a specific application example of the present invention;

[0088] Figure 14 Comparison schematic diagram of surface Q fields obtained by different characterization methods in a specific application example of the present invention;

[0089] Figure 15 Comparison schematic diagram of prestack time migration profiles with different Q field compensations applied in the study area in a specific application example of the present invention;

[0090] Figure 16 Schematic diagram of surface Q field established for the test line in Xiaotangnan working area in a specific application example of the present invention;

[0091] Figure 17Schematic diagram of comparison before and after surface absorption compensation of seismic records on the test line in the Xiaotang South Work Area in a specific application example of the present invention;

[0092] Figure 18 Schematic diagram of comparison of seismic profiles processed with new and old static correction amounts on the test line in the Xiaotang South Work Area in a specific application example of the present invention;

[0093] Figure 19 Schematic diagram of the structure of a near-surface seismic parameter characterization device in the desert area in an embodiment of the present invention;

[0094] Figure 20 Schematic diagram of the structure of the feature function establishment unit in the embodiment of the invention Figure 1 ;

[0095] Figure 21 Schematic diagram of the structure of the feature function establishment unit in the embodiment of the invention Figure 2 ;

[0096] Figure 22 Schematic diagram of the structure of the feature function establishment unit in the embodiment of the invention Figure 3 ;

[0097] Figure 23 Schematic diagram of the structure of the Q-field characterization unit in the embodiment of the invention;

[0098] Figure 24 Schematic diagram of the structure of an electronic device in the embodiment of the invention. Detailed implementation manners

[0099] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0100] The embodiments of the present invention provide a detailed implementation manner of a method for characterizing near-surface seismic parameters in a desert area. Refer to Figure 2 , and the method specifically includes the following contents:

[0101] Step 100: Divide the desert area into an upper part and a lower part from top to bottom according to the water table of the desert area determined in advance.

[0102] In this embodiment, a bottom layer that is relatively stable in the whole target work area and shows characteristics of low-frequency variation in the area is found as the water table, that is, the structural interface of the longitudinal two-phase or multi-phase structure characteristics in the desert area. The surface structure above the water table is characterized by the characteristics of a non-linear continuous medium structure, generally presenting two types of non-linear continuous medium characteristic parameters of aeolian dunes and stable dunes and it is difficult to determine a clear demarcation line. The surface structure below the water table is characterized by a layered medium structure, presenting a two-layer or multi-layer structure characteristic.

[0103] Step 200: Establish the characteristic function of the upper part and the characteristic function of the lower part, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure.

[0104] Realize the detection of the near-surface structure in the desert area and the characterization of the characteristic function step by step longitudinally and regionally horizontally. Specifically, taking the water table as the boundary, the problem of characterizing the near-surface structure in the desert area is simplified to the solution of the problem of the fusion of the characterization of the non-linear continuous medium structure characteristics overlying the water table and the planar regional characterization method, and the longitudinal step-by-step progressive characterization of the layered medium structure characteristics underlying the water table. That is, first take the water table as the bottom boundary of the non-uniform continuous medium (low-velocity zone) structure. According to the progressive fusion method of the longitudinal structure characteristics characterization and the planar regional structure characteristic function characterization of the non-linear continuous medium theory, a characteristic function that can more accurately characterize the non-linear continuous medium (low-velocity layer) structure overlying the water table can be constructed. Based on this characteristic function, the seismic data is corrected, and basically the influence of the sand dunes overlying the water table on the seismic data is eliminated; then the part that has not been completely corrected is used as a virtual uniform medium thin layer overlying the layered medium (high-velocity layer) structure, and a layered medium structure system is constructed together with the high-velocity layer for comprehensive research, and the characteristic parameter field of the layered medium structure is obtained by fine analysis; finally, the characteristic parameters of the two-phase or multi-phase structure near the surface in the desert area constructed step by step are fused to construct the characteristic parameter field of the near-surface structure in the desert area, and the influence correction of the near-surface structure characteristic parameters of the seismic data is carried out respectively, and basically the influence of the near-surface structure in the desert area on the seismic wave field is eliminated.

[0105] Step 300: Establish the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part.

[0106] Compared with the absorption attenuation effect of the deep bottom layer medium, the absorption attenuation of the near-surface medium to the high-frequency components of seismic waves is one of the important factors reducing the resolution of seismic data; the absorption of the surface medium to the high-frequency components of seismic waves accounts for about 80% of the total absorption of all strata. It can be seen that the absorption attenuation compensation processing of the near-surface medium has become the key to the success or failure of high-resolution seismic exploration, and its core is to accurately construct the near-surface Q-field characterization function.

[0107] When step 300 is implemented, specifically: the established low-deceleration zone Q field and the high-velocity layer Q field are integrated (multiplied by their respective travel-time accumulations) to obtain the integrated Q field of the near-surface absorption attenuation parameter relative to the datum plane. This Q field can be the accumulated total attenuation coefficient or the surface equivalent Q field (multiplying by the total travel-time of the surface layer is the total attenuation coefficient). Using this Q field for seismic wave absorption compensation processing, seismic data with the surface absorption effect eliminated is obtained.

[0108] As can be seen from the above description, the method for characterizing near-surface seismic parameters in desert areas provided by the embodiments of the present invention: First, it provides a method for characterizing the near-surface structure feature function and parameters step by step with complex spatial (longitudinal and transverse) feature variations, accurately depicting the spatial variation characteristics of the near-surface formation parameters in the desert area; Second, it provides a step-by-step method for obtaining the absorption attenuation parameters of the near-surface structure in the desert area, further improving the calculation accuracy of the Q value of the near-surface structure in the desert area and the accuracy and reliability of constructing the Q field with high precision; Third, relying on the constructed near-surface Q field in the desert area, it further improves the accuracy of the near-surface structure absorption compensation processing in the desert area, laying a foundation for improving the resolution ability of seismic data and better serving oil and gas exploration.

[0109] In one embodiment, referring to Figure 3 , the establishment of the characteristic function of the formation above the water table in step 200 includes:

[0110] Step 201: Classify the above part to generate multiple dune type partitions;

[0111] Specifically, based on the comprehensive investigation of dune types and analysis of plane distribution characteristics in the study area, the dune types and distribution characteristics in the study area are divided, and then various dune type partitions in the study area are further subdivided.

[0112] Step 202: Obtain the characterization function of each partition in the multiple dune type partitions;

[0113] Determine the main influencing factors of the surface structure characteristic parameters of various dune types in each type of partition in the area, and conduct "dune curve" characteristic parameter analysis and characterization function by comprehensive analysis of various methods such as micro-logging and large refraction for each type of dune;

[0114] Step 203: Establish the surface structure model of the control points of the above part;

[0115] Carry out surface surveys of near-surface control points in the study area (such as control point micro-logging), construct the surface structure model of control points, determine the two-phase medium boundary, and then construct the surface structure framework of control points in the study area;

[0116] Step 204: With point control as a constraint condition, establish the characteristic parameter field of each partition according to the characterization function;

[0117] Specifically, with the point control (control point) as the constraint, a dune structure characteristic parameter field (such as velocity, thickness, Q field, etc.) in the desert area of the study area is established according to the characterization functions of various dune types.

[0118] Step 205: Generate the characteristic function of the upper part according to the model and the characteristic parameter field.

[0119] In one embodiment, referring to Figure 4 , the establishment of the characteristic function of the strata above the water table in step 200 further includes:

[0120] Step 206: Perform correction on the characteristic parameter field for the influence of characteristic parameters to generate a corrected seismic record.

[0121] Specifically, based on the constructed dune structure characteristic parameter field in the study area, carry out correction for the influence of characteristic parameters to basically eliminate the influence of the dune part in the desert area on the seismic wave field.

[0122] In one embodiment, referring to Figure 5 , the establishment of the characteristic function of the strata below the water table in step 200 includes:

[0123] Step 20a: Generate the layered medium model of the lower part according to the seismic record and the layered medium structure.

[0124] It can be understood that there are inevitably errors (residual values of correction) after the characterization of the near-surface structure characteristic parameters of the dunes and the correction of the influence on the seismic wave field. This error and the layered medium structure underlying the water table together constitute a layered medium model that basically eliminates the influence of the dunes.

[0125] Step 20b: Use the first-arrival refraction tomography method and / or the first-arrival refraction energy attenuation analysis method to obtain the characteristic parameter field of the layered medium model.

[0126] Adopt the characterization function of the layered medium structure characteristic parameters (such as the first-arrival refraction tomography method, the first-arrival refraction energy attenuation analysis method, etc.) to finely analyze and obtain the characteristic parameter field of the layered medium structure.

[0127] Step 20c: Establish the characteristic function of the lower part according to the characteristic parameter field.

[0128] In one embodiment, referring to Figure 6 , step 300 further includes:

[0129] Step 301: Establish the Q field of the upper part according to the characteristic function of the upper part.

[0130] Step 302: Establish the Q field of the lower part according to the characteristic function of the lower part.

[0131] Step 303: Generate the near-surface Q field of the desert area by fusing the Q field of the upper part and the Q field of the lower part.

[0132] In steps 301 to 303, the established low-velocity layer Q field (upper part) and the high-velocity layer Q field (lower part) are synthesized (multiplied by their respective travel-time accumulations) to obtain the comprehensive Q field of the near-surface absorption attenuation parameter relative to the datum plane. This Q field can be the cumulative total attenuation coefficient or the surface equivalent Q field (multiplying by the total travel time of the surface layer gives the total attenuation coefficient). Using this Q field for seismic wave absorption compensation processing, seismic data with the surface absorption effect eliminated is obtained.

[0133] The method for characterizing and correcting the Q field of the surface layer structure in the desert area is to divide the travel time of each layer by its respective Q value and then accumulate, that is:

[0134] Q 综 = Q 低 + Q 基 (1)

[0135] Where: Q 低 = B 1-γ × A -γ × T 低 γ (2)

[0136] Q 基 = (H 基 - H 高 ) / V 高 / Q 高 (3)

[0137] γ = 1 - β / α (4)

[0138] T 低 (H) = B × H α (5)

[0139] Q 低 (H) = A × H β (6)

[0140] In the formula, T_low is the total travel time of the low-velocity layer, H_base is the elevation of the datum plane, H_high is the elevation of the top surface of the high-velocity layer, V_high is the velocity of the high-velocity layer, Q_low is the total attenuation coefficient of the low-velocity layer, and Q_base is the total attenuation coefficient of the part between the top surface of the high-velocity layer and the datum plane.

[0141] If an equivalent Q field of the near surface is to be established, then Q_comprehensive needs to be divided by the near-surface static correction amount T_static, that is:

[0142] Q 等 = Q 综 / T 静 (7)

[0143] Where: T 静 = T 低 +(H 基 - H 高 ) / V 高 (8)

[0144] In the formula, Q 等 is the near-surface equivalent Q field, and T 静 is the near-surface static correction amount.

[0145] Based on the fine analysis and research of the near-surface structure model and spatial distribution characteristics in the desert area, the present invention innovatively studies the theoretical method and application method for characterizing the structure characteristic function of the near-surface two-phase or multi-phase medium in the desert area, the method idea and method process for building and compensating the absorption attenuation space, etc.

[0146] To further illustrate the present solution, taking the desert area of the Tarim Basin as an example, the present invention provides a specific application example of the method for characterizing near-surface seismic parameters in the desert area. The specific application example specifically includes the following content. See Figure 7 .

[0147] In recent years, the step-by-step characterization method of the near-surface structure characteristic function in the desert area, which has been deeply studied, is an innovative method for solving the problem of investigating the near-surface structure formation parameters in complex surface areas such as the desert area. This method is based on the comprehensive analysis and research of the spatial distribution characteristics of the near-surface structure in the western desert area of China. Its overall idea is as follows:

[0148] See Figure 8 . Due to the complexity and particularity of the near-surface structure in the desert area, there are two key problems in the characterization of its characteristic function. One is that in the vertical direction, there is a two-phase or multi-phase structure characteristic of a non-linear continuous medium (low-velocity layer) overlying the water table and a layered medium (high-velocity layer) underlying it. It is difficult to accurately characterize the characteristic parameters of the two-phase or multi-phase structure with the same theory and method. The other is that in the plane (in the horizontal or spatial direction), the structure of the extremely thick non-uniform continuous medium (low-velocity zone) overlying the water table is irregular and has high-frequency variations, which are difficult to accurately characterize in detail and affect the accurate characterization of the characteristic parameters of the underlying layered medium (high-velocity layer). The root and core of the two key problems lie in the fact that the irregular high-frequency variations of the non-uniform continuous medium (low-velocity zone) overlying the water table are difficult to accurately characterize in detail (neither possible nor necessary). The method idea is as follows:

[0149] ① Taking the water table with little undulation and stable distribution and presenting low-frequency variation characteristics in the plane as the interface, the problem of characterizing the near-surface structure characteristic function in the desert area is divided into a two-phase or multi-phase structure system of a non-linear continuous medium (low-velocity layer) overlying and a layered medium (high-velocity layer) underlying, and the problem is solved step by step;

[0150] ②Rather than hoping to accurately characterize the structural characteristic function of the non-linear continuous medium (low velocity reduction layer) overlying the water table in the desert area (which is neither achievable nor necessary), it is hoped to obtain a relatively accurate characterization of the structural characteristic function of the overlying non-linear continuous medium (low velocity reduction layer). Using this characteristic function (characteristic parameter field) to correct seismic data can basically eliminate its impact on seismic data, solve the problem that the extremely thick low velocity reduction zone of sand dunes causes the method indicators of the existing layered medium theory and corresponding software systems to exceed the limit, and lay a foundation for the subsequent characterization and correction of the near-surface structural characteristic function in the desert area. There will inevitably be residual errors in the correction of the low velocity reduction layer characteristic function (characteristic parameter field), which can be regarded as a uniform medium thin layer overlying the layered medium (high velocity layer) structure under the water table and incorporated into the research of the layered medium structure system under the water table;

[0151] ③The structure of the non-linear continuous medium (low velocity reduction layer) overlying the near-surface water table in the desert area has zonal characteristics, including both regional zoning and classification characteristics, as well as the zoning and classification characteristics of each sand dune (sand ridge) body. By analyzing and studying its characteristics and laws, and according to the non-uniform continuous medium theory, it is expected to achieve a relatively accurate characterization of the characteristic function;

[0152] ④The inevitable residual errors after correcting the characteristic function (characteristic parameter field) of the non-uniform continuous medium structure (low velocity reduction layer) overlying the near-surface water table in the desert area are regarded as a virtual uniform medium thin layer overlying the layered medium (high velocity layer) structure under the water table, and a layered medium structure system is constructed for comprehensive research. Using functions such as the first arrival refraction tomography method and the first arrival refraction energy attenuation analysis method to finely analyze and obtain the characteristic parameter field of the layered medium structure;

[0153] ⑤Fuse the characteristic parameter field of the non-uniform continuous medium (low velocity reduction zone) structure overlying the water table and the characteristic parameter field of the layered medium structure system constructed by the remaining amount after correcting the characteristic function of the layered medium structure (high velocity layer) underlying the water table and the overlying formation of the water table to construct the near-surface structural characteristic parameter field in the desert area;

[0154] ⑥For the fused near-surface structural characteristic parameter field in the desert research area, conduct corrections on the influence of the near-surface structural characteristic parameters of seismic data respectively to basically eliminate the influence of the near-surface structure in the desert area on the seismic wave field.

[0155] S1: Determine the water table in the desert area of the Tarim Basin.

[0156] Specifically, in the Tarim Basin area, this interface is sought. This interface has the following characteristics: The sand dunes above the water table exhibit the characteristics of a non-linear continuous medium, with planar fluidity and significant undulations along the regional monsoon direction. They are relatively loose, with a certain degree of compaction change from top to bottom, severe absorption attenuation, and rapid and difficult-to-accurately obtain changes in characteristic parameters. Below the water table is a layered medium structure with relatively stable planar distribution, including water-bearing fine sand, weathered layer, clay layer, or diagenetic strata, etc. The parameters within the layer change very little, and the absorption attenuation is relatively small compared to the low-velocity zone sand dunes overlying the water table.

[0157] The water table in the desert area is usually the top surface of the high-velocity layer, and it is the boundary line of the two-phase or multi-phase structure characteristics between the overlying non-linear continuous medium (low-velocity layer) and the underlying layered medium (high-velocity layer), with relatively small undulations and stable distribution on the plane, presenting low-frequency change characteristics.

[0158] Based on the analysis of the water table survey data, micro-logging or small refraction data, combined with the regional water table data and results, as well as the understanding of the first-arrival refraction tomography analysis of the previous seismic data, further refine the spatial distribution of the desert water table in the study area, and then determine the interface of the two-phase medium structure of the non-uniform continuous medium and the layered medium in the desert of the study area, and provide basic data for the classification and zoning of the sand dune types in the study area.

[0159] S2: Divide the desert area into the upper part and the lower part from top to bottom according to the water table.

[0160] According to the on-site detection, field tests and in-depth research and analysis in recent years, combined with a large number of field survey data of the near-surface structure in the desert area such as micro-logging in the Tarim Basin (especially the eastern Tarim block) over the years, the following research results on the longitudinal characteristics of the near-surface structure in the desert area are formed. Specifically as follows:

[0161] 1) The near-surface structure in the desert area shows the two-phase or multi-phase structure characteristics of a non-linear continuous medium and a layered medium longitudinally.

[0162] The longitudinal structure of the aeolian sand dunes in the desert area of the Tarim Basin shows different change characteristics, and as a whole, it shows the two-phase or multi-phase structure characteristics such as a non-linear continuous medium and a layered medium from top to bottom. Among them, with the relatively stable water table that exists as a whole in the desert area of the Tarim Basin and shows low-frequency change characteristics as a structural plane, a two-phase or multi-phase structure characteristic of the non-linear continuous medium structure above it and the layered medium structure below it is constructed.

[0163] 2) The longitudinal sub-structure of the near-surface structure in the desert area.

[0164] The longitudinal structure of the aeolian sand dunes in the desert area of the Tarim Basin shows the two-phase or multi-phase structure characteristics of a non-linear continuous medium and a layered medium from top to bottom (as shown in Figure 9 ), and the specific subdivision is as follows.

[0165] ① Subdivision of the longitudinal structural characteristics of the non-linear continuous medium structure.

[0166] The surface structure above the water table exhibits the characteristics of a non-linear continuous medium structure, generally presenting two types of non-linear continuous medium characteristic parameters, namely aeolian sand dunes and stable sand dunes, and it is difficult to determine a clear demarcation line.

[0167] Ⅰ. Aeolian sand dunes. In the first few meters near the surface (generally less than ten meters), they have planar fluidity along the regional monsoon direction, with non-linear variation characteristics mainly in terms of compaction degree and supplemented by water content in the longitudinal direction. They are relatively loose, with the most severe absorption and attenuation, rapid parameter changes and difficult to accurately obtain (for example, the longitudinal wave velocity is often between 150 - 600 m / s and varies with depth), and the absorption and attenuation of seismic waves are intense.

[0168] Ⅱ. Stable sand dunes. From below the aeolian sand dunes in the first few meters near the surface to the water table, there are certain changes in compaction and water content; in the longitudinal direction, it has non-linear characteristics jointly affected by changes in water content and compaction degree. The longitudinal wave velocity often varies between 500 - 1400 m / s with depth, with relatively large absorption and attenuation of seismic waves and also relatively large parameter changes.

[0169] ② Subdivision of the longitudinal structural characteristics of the layered medium structure.

[0170] The surface structure below the water table exhibits the characteristics of a layered medium structure, presenting a two-layer or multi-layer structure: generally divided into two large layers, namely the unstable high-velocity layer and the stable high-velocity layer, and can be further sequenced and subdivided according to characteristics such as lithology.

[0171] Ⅰ. Unstable high-velocity layer. The part from below the water table to the top surface of the stable high-velocity layer consists of water-bearing fine sand, weathered layer or clay layer, etc. The parameters within the layer change very little and the absorption and attenuation are not serious.

[0172] Ⅱ. Stable high-velocity layer part. It is often hard clay or diagenetic strata, with basically unchanged parameters within the layer and relatively small absorption and attenuation.

[0173] 3) The water table, which is relatively stable in distribution and exhibits regional low-frequency variation characteristics, is the structural interface of the longitudinal two-phase or multi-phase structure characteristics in the desert area.

[0174] In the desert area of the Tarim Basin, there is a water table with relatively small undulations, relatively stable structural characteristics, and exhibiting regional low-frequency variation characteristics. Above it is a stable sand dune with non-linear characteristic changes mainly in terms of water content change and supplemented by compaction degree change, and the lithology is sand; below it is a layered medium with lithologies such as water-rich sand layers and clay layers; this relatively stable water table is the structural interface of the longitudinal two-phase or multi-phase structure characteristics such as the near-surface non-linear continuous medium and layered medium in the desert area.

[0175] S3: Establish the characteristic function of the upper part.

[0176] Specifically, with the phreatic surface as the interface, methods such as "dune curve" parameter investigation and characterization function analysis are used to construct a characterization function field for the near-surface structure of dunes, and correction of the influence of characteristic parameters is carried out respectively to eliminate the influence of the near-surface structure of dunes in the desert area on the seismic wave field.

[0177] Next, based on a comprehensive investigation of the dune types and an analysis of the planar distribution characteristics in the study area, the dune types and distribution characteristics in the study area are divided, and then various dune type sub-regions in the study area are further subdivided; the main influencing factors of the characteristic parameters of the surface layer structure of various dunes in each type of sub-region in the study area are studied, and "dune curve" characteristic parameter analysis and characterization functions are carried out for each type of dune by comprehensive analysis of various methods such as micro-logging and large refraction; with the control points of the regional dune surface layer structure investigation as the constraints, and the "dune characteristic curves" of various dunes obtained by on-site investigation and research analysis as the characterization functions, the characteristic parameter fields of the non-linear continuous medium surface layer structure of dunes are obtained and constructed respectively; according to the constructed characteristic parameter field of the near-surface structure of dunes in the study area, correction of the influence of characteristic parameters is carried out respectively to basically eliminate the influence of the near-surface structure of dunes in the desert area on the seismic wave field.

[0178] Furthermore, the methods for characterizing the longitudinal characteristic parameters of the near-surface structure in the desert area include: the near-surface parameters generally include velocity, thickness, density, absorption coefficient, etc. In layered media, the near-surface parameters are mainly represented by stratified constants, that is, the parameters are unchanged within the same layer and are constants; the surface layer parameters in different layers or different locations are the ones that change. In continuous media, its spatial distribution shows a power function characterization feature.

[0179] Through the analysis of actual data, the near-surface structure in the desert area presents a dual-phase medium structure combining non-uniform continuous medium characteristics and layered medium characteristics, and the parameters such as the velocity, density, and absorption coefficient of the dunes show a changing trend of the dual-phase medium structure. The analysis of a large number of micro-logging data in the desert area shows that the dunes present non-linear regular characteristics, regardless of whether the dunes are large dunes with a height of hundreds of meters or small dunes less than 10 meters.

[0180] Through the analysis of a large number of micro-logging data in the desert area, it is found that the near-surface structure in the desert area is bounded by the phreatic surface and generally presents the dual-phase medium structure characteristics of overlying non-uniform continuous medium and underlying layered medium ( Figure 10 as shown); among them, the overlying continuous medium presents different power function characteristics in segments (T(H) = B × H α), similar to the understanding of the sequence subdivision of the heterogeneous continuous medium overlying the water table in the desert area near the surface, that is, the heterogeneous continuous medium structure can be divided into two (or more) sub-layers for feature characterization. Therefore, the present invention respectively adopts the parameter characterization methods of continuous medium and homogeneous layered medium for different structural characteristics above and below the near surface to accurately depict the near-surface parameter characteristics, and studies the method for segmental fusion characterization of the characteristic curves of the micro-logging data of the near-surface structure in the desert area: First, the demarcation point of the water table is determined, and the characterization section of the overlying heterogeneous continuous medium structure and the linear characterization section of the layered medium structure are divided; Second, different power functions are respectively used to characterize the characteristics of different characterization sections of the continuous medium structure; Third, the fusion method of the power function characteristic functions of adjacent characterization sections is adopted to realize the fusion of the power function characteristic functions between adjacent characterization sections, and solve the problem that it is difficult to accurately determine and identify the subdivision sequence interface of the heterogeneous continuous medium structure overlying the water table. For example, the variation relationship of the near-surface time-depth data of a certain measurement point (see Figure 10 ) shows two characteristics. The low-velocity reduction layer shows a power function characteristic, while the high-velocity layer shows a linear characteristic; its time-depth curve can be divided into two large segments and three small segments: there are 2 inflection points (at 5m and 60m) on the curve. The second inflection point from shallow to deep is the demarcation point between the continuous medium structure and the layered medium, that is, the water table, which divides the curve into two large segments; the characterization function of the underlying layered medium structure is a constant with sequence characteristics (such as V = 1932m / s); above this second inflection point is the continuous medium, which is divided into two small segments for characterization. Above the first inflection point, power function 1 is used for characterization (such as V = 4.72H 0.7336 ), and above the second inflection point, power function 2 is used for characterization (such as V = 4.36H 0.7632 ).

[0181] The segmental characterization method is carried out on all surface investigation data such as micro-logging in the study area to realize the characterization of the characteristic function of the near-surface structure in the desert area, and then the characterization functions of the two-phase medium structure and the subdivision sequence in the desert area are constructed, and the overlying continuous medium structure model and the underlying layered medium structure model of the near-surface structure in the desert area are constructed.

[0182] In contrast, the method for the zonal classification of lateral characterization and correction of dune characteristic parameters includes: Dunes in the desert area, i.e., the low-velocity reduction layer, have different lateral characterizations from those of the high-velocity layer, and the lateral variation relationship of the characteristic parameters of the low-velocity reduction layer shows complex changes. Research shows that the near-surface structure in the desert area exhibits zonal classification characteristics in regional space, and it is necessary to adopt a combination of step-by-step characterization and spatially zonal characterization methods to achieve the characteristic function characterization and parameter extraction of the near-surface structure; at the same time, each dune (sand ridge) individual also has zonal characterization characteristics; the dune surface can generally be divided into the windward area, leeward area, and flat area, and different dune curves (or power functions) are used for parameter fitting calculations respectively, that is, the "lateral zonal method characterization" of the near-surface structure of the dune. Whether it is the micro-logging method or the large refraction method, the dune curves fitted at different positions such as the windward slope and leeward slope of the dune are different, which has a great relationship with the compaction effect and water content at different positions of the dune. Especially on both sides of a relatively large sand ridge, the difference between the windward slope and the leeward slope is relatively large, and separate fitting analysis is required. The seismic wave travel times of the leeward slope and the windward slope with the same sand thickness are significantly different. The seismic wave travel time of the leeward slope is significantly longer than that of the windward slope. Compared with the windward slope, the wave velocity of the leeward slope is lower and the absorption attenuation is greater, and it cannot be characterized by the same regular characteristics or characteristic functions, otherwise it will lead to relatively large errors. Therefore, the dunes (low-velocity reduction zones) of the near-surface structure in the desert area are divided into three categories: the windward area, leeward area, and flat area, and the lateral characteristic parameters are characterized separately to determine the change rules of their respective dune curves. By determining the lateral change rules of the dune zones, the "zonal method characterization" of the dunes in the desert area is scientific and effective, and the characteristics of the dunes in the desert area can be characterized more accurately.

[0183] S4: Establish the characteristic function of the lower part.

[0184] Specifically, the remaining error after the correction processing of the characteristic function of the non-linear continuous medium structure overlying the water table is used as a virtual homogeneous medium thin layer overlying the layered medium (high-velocity layer) structure under the water table, and a surface structure of the layered medium under the water table that basically eliminates the influence of the characteristic parameters of the non-linear continuous medium surface layer of the dune is constructed. Through the characteristic parameter characterization function of the layered medium structure (such as the first-arrival refraction tomography method, the first-arrival refraction energy attenuation analysis method, etc.), the characteristic parameter field of the layered medium structure is finely analyzed and its influence is eliminated.

[0185] Next, on the basis of basically eliminating the influence of the near-surface structure of sand dunes in the desert area on the seismic wave field, the incompletely corrected part is regarded as a thin layer of layered medium covering the water table, which together with the layered medium structure underlying the water table constitutes a layered medium model with basically eliminated sand dune influence; layer medium structure characteristic parameter characterization functions such as the first-arrival refraction tomography method and the first-arrival refraction energy attenuation analysis method are used to finely analyze and obtain the layer medium structure characteristic parameter field; according to the constructed near-surface layer medium structure characteristic parameter field of the study area, characteristic parameter influence correction is carried out respectively to basically eliminate the influence of the near-surface structure in the desert area on the seismic wave field.

[0186] Furthermore, the lateral characterization of near-surface high-velocity layer characteristic parameters such as velocity and density parameters is carried out by obtaining the parameter field through the plane interpolation method constrained by control points. The remaining error that inevitably exists after correcting the characteristic function (characteristic parameter field) of the non-uniform continuous medium structure (low-velocity reduction layer) overlying the water table in the desert area is regarded as a virtual uniform medium thin layer overlying the structure of the layered medium (high-velocity layer) underlying the water table, and a layered medium structure system is constructed for comprehensive research; layer medium structure characteristic parameter characterization functions such as the first-arrival refraction tomography method and the first-arrival refraction energy attenuation analysis method are used to finely analyze and obtain the layer medium structure characteristic parameter field.

[0187] See Figure 11 , it should be noted that the characteristic parameter influence correction generally completes the near-surface structure characteristic parameter influence correction processing by using one of the following two methods:

[0188] Ⅰ. Step-by-step field construction and one-step correction method. Based on the fused and constructed near-surface structure characteristic parameter field of the desert area, near-surface characteristic parameter influence correction is carried out based on the original seismic data to comprehensively eliminate the influence of the near-surface structure in the desert area on the seismic wave field;

[0189] Ⅱ. Step-by-step progressive field construction correction method. Relying on the corrected seismic data, based on the near-surface structure characteristic parameter field of the layered medium below the water table of the study area constructed in step 7, near-surface structure characteristic parameter influence correction of the layered medium is carried out to gradually and basically eliminate the influence of the near-surface structure in the desert area on the seismic wave field.

[0190] S5: Construct the surface structure Q field.

[0191] Specifically, the Q field of the sand dune part can be established first according to the surface survey data. After quickly compensating the seismic records, then the Q value is calculated on the single-shot records that basically meet the previous Q value calculation conditions, and then the near-surface Q field is established. Therefore, a new step-by-step Q field establishment method needs to be adopted to achieve the purpose of improving the quality of seismic data.

[0192] As described above, with the phreatic surface presenting low-frequency variation characteristics in a stable distribution with little undulation on the plane as the demarcation line, the longitudinal step-by-step progressive method and the plane partition fusion method are respectively used to characterize the characteristic parameters of the non-linear continuous medium structure of the dunes overlying the phreatic surface and the characteristic parameters of the layered medium structure underlying the phreatic surface, and the influence correction of the characteristic parameters of the two-phase or multi-phase medium structure is realized step by step.

[0193] The established low-velocity reduction zone Q field and the high-velocity layer Q field are integrated (multiplied by their respective travel time accumulations) to obtain the comprehensive Q field of the near-surface absorption attenuation parameter relative to the reference plane. This Q field can be the cumulative total attenuation coefficient or the surface equivalent Q field (multiplying by the total travel time of the surface layer is the total attenuation coefficient). Using this Q field for seismic wave absorption compensation processing, the seismic data with the influence of surface absorption eliminated is obtained.

[0194] Specifically, analyzing the lateral variation relationship of the high-velocity layer parameter Q in the desert area (see Figure 12 ), it shows a certain regularity with the velocity parameter. Generally speaking, the Q value increases with the increase of velocity, but the distribution of data points is relatively scattered, and it is still difficult to show its regularity. The data fitting error is large and it is difficult to meet the requirements; but in the past, only the fitting relationship could be used to establish the high-velocity layer Q field according to this regularity. Through analysis, it is found that the absorption attenuation parameter Q has a certain relationship with the dune parameters (which can be calculated based on surface survey data and measurement data), and has good regularity characteristics (see Figure 13 ). The high-velocity layer Q field can be converted and interpolated using the dune parameter field of the conventional near-surface structure survey, which is different from the method of converting and interpolating to establish the Q field using the velocity parameter in the past. Therefore, the lateral characterization of the near-surface structure characteristic function in the desert area of the present invention also needs to adopt a step-by-step characterization method. Different field establishment methods are used for the low-velocity reduction layer and the high-velocity layer respectively, that is, the spatial partition method for characterizing the characteristic parameters of the non-linear continuous medium structure of the dunes overlying the phreatic surface and the statistical interpolation method for characterizing the characteristic parameters of the layered medium structure underlying the phreatic surface.

[0195] Application effect: The near-surface characteristic parameters include velocity, thickness, density, Q, etc. Structural parameters such as velocity and thickness are the characterization basis of the parameter Q. The Q parameter is often a comprehensive reflection of the near-surface structure characteristic parameters, with more complex spatial changes and greater characterization difficulty; thus, the step-by-step characterization and field establishment correction of the near-surface structure Q characteristic parameters in the desert area can better reflect the difficulty of the research and the effect of research application.

[0196] A large number of micro-logging data in the desert area show that not only does the velocity of the sand dunes (low-velocity reduction zones) vary non-linearly with depth, but also the absorption parameter or attenuation factor Q of the sand dunes varies non-linearly with depth. It is not until the high-velocity layer rich in water and the layered medium structure below that the Q parameter shows relatively stable or slightly increasing characteristics. Characterizing the near-surface Q-depth relationship in the desert area step by step based on micro-logging data is still a relatively reliable method, and the method for obtaining the surface layer Q value based on dual-well micro-logging data is still effective in the desert area; the Q-depth relationship of the near-surface structure in the desert area presents the characteristics of coexistence of non-linearity and linearity. The Q-depth relationship of the surface low-velocity reduction zone (sand dunes) presents non-linear characteristics, and the Q-depth relationship of the high-velocity layer below it presents linear characteristics (Q is basically a constant).

[0197] 1) The accurate characterization of the time-depth relationship improves the calculation accuracy of the single-point Q value.

[0198] The lithology of the sand dunes (low-velocity reduction zones) is single, but the velocity is no longer a constant due to compaction, and the time-depth relationship is non-linear. The characterization method of the surface low-velocity reduction zone characteristic function is adjusted from the previous linear stratification fitting method of layered media to the non-linear characterization method of segmented power function characterization and inter-segment power function fusion of non-uniform continuous media sub-sequence, effectively improving the accuracy and precision of the time-depth relationship characterization and characteristic parameter characterization of single-point micro-logging data. Through forward and inverse modeling of the model and comparison of new and old methods, the high accuracy of single-point Q value calculation is verified. As shown in Table 1, the given total surface layer absorption amount of a single point is 79, and the result characterized by the new method is 78.6, with the Q value calculation accuracy improved by more than 20% compared with the old method.

[0199] Table 1 Comparison of the effects of new and old methods

[0200] Total absorption Absolute error Relative error Theory 79.0 0.0 0.0％ Old method 61.0 -18.0 -22.8％ New method 78.6 -0.4 -0.6％

[0201] 2) The characterization method of zoning and the step-by-step extraction method of Q value improve the establishment accuracy of the surface layer Q field.

[0202] The zoning method for characterizing the near-surface two-phase medium structure in deserts and the step-by-step extraction of Q values improve the accuracy of surface Q field construction. First, the Q field step-by-step zoning method is used to characterize the near-surface two-phase medium structure in the desert using a continuous medium representation of the low-deceleration zone, power function fitting, and zoning interpolation. The Q field step-by-step zoning method is used to characterize the high-speed layer above the floating datum using layered medium representation, linear fitting, and empirical formula conversion. The two Q fields from these step-by-step characterizations are then fused to construct a surface Q field, which is then rapidly compensated using the surface absorption attenuation linear compensation method. Then, based on the seismic records processed with rapid absorption attenuation compensation for the low-deceleration layer, seismic first-arrival waves are picked up and tomographic analysis is performed to construct the high-speed layer Q field. Finally, the Q field of the nonlinear continuous medium structure in the low-deceleration zone of the near-surface two-phase medium structure in the desert is fused with the Q field of the high-speed layered medium to construct a comprehensive Q field of the near-surface structure in the desert. Compared with the "old method" of Q field construction and fusion method that used a single medium (layered medium or continuous medium) structure to characterize the near-surface structural characteristic function of the desert area, the "old method" of using seismic record first-arrival tomography analysis based on the deep-Q value curve calibration constraints of surface absorption parameter survey data to characterize the Q parameter field construction has effectively improved the scientific nature of the method and the accuracy of characterization and the precision of field construction have been effectively improved. Figure 14 This is a plan view of the Q field constructed using different methods in the experimental area. Overall, the absorption and attenuation parameters of the near-surface structure in the desert region constructed using the two methods show good regularity and correlation with the elevation map data of the surface undulation, and also show good spatial correlation with the surface elevation of the desert study area. However, detailed analysis reveals two differences: ① The Q value constructed using a single medium is generally smaller, and the influence of the absorption and attenuation of the near-surface structure is insufficiently corrected, which affects the frequency spreading processing and resolution improvement of the seismic data. ② The step-by-step zoning characterization method accurately depicts the differences in the absorption and screening characteristics of the windward and leeward sides of the sand dunes. The absorption attenuation on the leeward side is greater than that on the windward side, which is consistent with the actual situation. However, the Q field constructed based on a single medium in the past was unable to characterize the spatial differences in the Q field in the sand dunes. The Q field constructed using the step-by-step zoning characterization method for the near-surface structure in the desert region is more accurate and reliable.

[0203] 3) The Q field established using the new invention method achieves better compensation effect.

[0204] Figure 15 These are offset seismic profiles from the experimental area using different Q-field compensation methods. It's clear that the new Q-field compensation method effectively compensates for the dominant frequency more fully, broadening the dominant frequency band by approximately 10 Hz. This improves profile resolution and geologic imaging, further sharpening the focus on the beaded structure of the karst fractures and caves in the Gucheng 6 well, and providing clearer breakpoints. This also provides more reliable interpretation of small faults in the Yingshan Formation's weak reflection information. This innovative method effectively enhances the quality and resolution of seismic processing results, laying the foundation for the detailed calibration, identification, and characterization of carbonate and dolomite reservoirs.

[0205] Figure 14 It is the plan view of the Q field constructed by different methods in the experimental research area. The middle figure is the near-surface Q field constructed by the "one-step method" using a single medium (such as layered medium or continuous medium) (in this example, layered medium is used), and the right figure is the near-surface Q field constructed by the "step-by-step method". Generally speaking, the absorption attenuation parameters of the near-surface structure in the desert area constructed by the two methods and the elevation map of the surface undulation (left figure) data have good regularity and correlation, and have good spatial correlation with the surface elevation of the desert research area. However, through detailed analysis, two differences can be found: ① The Q value constructed by a single medium is generally small, and the influence correction of the absorption attenuation of the near-surface structure is insufficient, which affects the frequency extension processing of seismic data and the improvement of resolution ability; ② The step-by-step and zone-by-zone characterization method finely depicts the differences in absorption screening characteristics between the windward side and the leeward side of the sand dunes. The absorption attenuation on the leeward side is larger than that on the windward side, which is consistent with the actual situation. However, the Q field constructed based on a single medium in the past cannot represent the spatial differences of the sand dune Q field. The Q field constructed by the step-by-step and zone-by-zone characterization method of the near-surface structure in the desert area has higher accuracy and reliability.

[0206] Figure 15 It is the migrated seismic profile processed by different compensation methods in the ancient city test area. It can be clearly seen from it that the two-step compensation method compensates the dominant frequency more effectively, the resolution is improved, the bead-shaped structure of the karst fissure-cave body passing through Well 6 in the ancient city is more focused, the fault points are clearer, and the interpretation of the small faults of the weak reflection information in the Ying Mountain Formation is more credible. The innovation of the method effectively improves the quality and resolution ability of the seismic processing results, and lays a foundation for the fine calibration, identification and characterization of carbonate rock and dolomite reservoirs.

[0207] Figure 16 It is the Q field (profile view) built on the test line in the southern Xiaotang work area. The required Q field is the surface layer Q field with a reference plane of elevation 1000m. The brown curve in the figure represents the relative lateral variation of the total absorption attenuation amount (∑Δt i / Q i , enlarged display), and the blue line is the lateral variation of the ground elevation. This Q field has a certain matching relationship with the sand dunes. The sand dunes correspond to high absorption coefficients, especially the leeward slopes of the sand dunes correspond to stronger absorption attenuation amounts, and the overall variation trend is credible.

[0208] Figure 17It is the comparison of seismic records before and after the surface Q-field compensation on the test line in the southern Xiaotang work area. The compensated single-shot seismic record is obtained by performing absorption compensation processing on the near-surface Q-field in the desert area established by the newly invented step-by-step characterization and step-by-step extraction method, and the recording quality has been improved relatively well. For surface compensation, the high-frequency component has more energy and a larger amplitude increase than the low-frequency component. When reaching a certain high frequency, the compensation intensity drops sharply and basically no longer increases the energy. Therefore, after compensation, the low-frequency strong surface wave energy is hardly improved, while the effective wave is greatly improved. Relatively speaking, the signal-to-noise ratio of the compensated record is increased, and essentially the dominant frequency band is highlighted. The drastic changes in the dune undulations have a greater impact on seismic waves. Through compensation processing, this impact is greatly weakened, and the continuity of the event axis is improved, which is very beneficial to the improvement of the final seismic section quality.

[0209] Figure 18 It is the seismic section processed by different methods for extracting static correction amounts in the southern Xiaotang work area. Figure 18 The upper part is the desert surface elevation line. Figure 18 The middle part is the section processed with the static correction amount of the old method. Figure 18 The lower part is the section processed with the static correction amount of the new method (dune classification non-linear interpolation method). It is not difficult to see from the section that the wave group characteristics of the static correction amount extracted by the dune classification non-linear interpolation method are obvious, and the resolution and signal-to-noise ratio of the section are relatively high, and the influence of the dunes is better eliminated. The most obvious is the middle area in the figure. The event axis of the lower figure is more continuous and the imaging quality is higher than that of the upper figure.

[0210] In 2018, the step-by-step characterization method for the near-surface in the desert area and the step-by-step extraction method for absorption attenuation parameters were applied in the southern Xiaotang 3D seismic block in the Taklimakan Desert. Single-point data interpretation of 9 surface absorption parameter survey points and 44 conventional surface survey points was completed, a surface absorption attenuation parameter field (i.e., surface Q-field) including 204 full-coverage 12-km test lines was established, surface static correction amounts were extracted for more than 10,000 shot seismic data (3D seismic block), static correction processing, surface absorption attenuation compensation processing and analysis were carried out on the test line, etc., verifying that the drastic impact of the dune surface on seismic waves has been effectively weakened or eliminated.

[0211] In terms of Q-field establishment, in the past, the surface Q-field was organically combined with the Q-field of the large-shot first arrival method to establish a unified Q-field. The present invention is a two-step method for field establishment, with rapid surface absorption compensation processing in the middle, including two major parts: surface Q-field establishment and rapid absorption compensation, and Q-field establishment of the large-shot first arrival method. The new method invented was used to construct the near-surface Q-field in a two-step manner in the southern Xiaotang 3D seismic block, and good results were obtained. Figure 9 It is the Q-field established for the test line in the southern Xiaotang work area. This Q-field has a certain matching relationship with the dunes. The dunes correspond to a high total absorption amount, and the overall change trend is credible.

[0212] In terms of surface absorption compensation, Figure 17 It is the comparison of seismic records before and after surface Q-field compensation on the test line in the southern Xiaotang work area. For surface compensation, the energy and amplitude of high frequencies are increased more than those of low frequencies. When reaching a certain high frequency, the compensation intensity drops sharply and basically no longer increases the energy. Therefore, after compensation, the low-frequency strong surface waves are hardly improved, while the effective waves are greatly improved. Relatively speaking, the signal-to-noise ratio of the recorded data after compensation is increased, and essentially the dominant frequency band is highlighted. The drastic changes in dune undulations have a great impact on seismic waves. Through compensation processing, this impact is greatly weakened, and the continuity of the event axis is improved, which is very beneficial to the improvement of the final seismic profile quality.

[0213] In terms of static correction processing, starting from the origin of dunes, the distribution pattern of dunes is further understood. By analyzing the application effects of dune curve templates in different parts of dunes, the dunes are divided into windward slopes, leeward slopes, and flat areas according to the idea of dune curve templates. After research and analysis through zoning, it is found that the application effect is significantly improved within a certain range of dune thickness. Figure 11 It is the seismic profiles processed by different methods of extracting static correction amounts. The upper figure is the desert surface elevation line, the middle figure is the profile processed by the old method of static correction amount, and the lower figure is the profile processed by the new method (dune classification non-linear interpolation method) of static correction amount. It is not difficult to see from the profiles that the wave group characteristics of the static correction amount extracted by the dune classification non-linear interpolation method are obvious, the resolution and signal-to-noise ratio of the profiles are relatively high, and the influence of dunes is well eliminated. The most obvious is the middle area in the figure. The event axis in the lower figure is more continuous and the imaging quality is higher than that in the upper figure.

[0214] From the above description, it can be seen that the method for characterizing near-surface seismic parameters in desert areas provided by the specific application example of the present invention first divides the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table in the desert area; then, characteristic functions of the upper part and the lower part are established, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure; finally, a Q-field characterization function of the desert area is established according to the characteristic functions of the upper part and the lower part. Specifically, the present invention has the following beneficial effects:

[0215] 1) It lays a research foundation for constructing the near-surface two-phase medium structure model and distribution characteristics in the desert area.

[0216] It constructs a longitudinal model and sub-layer sequence characteristics of the near-surface two-phase or multi-phase medium structure in the desert area, and a spatial zoning and classification distribution pattern, clarifies that the water table is its demarcation line, simplifies the problem of characterizing the near-surface structure in the desert area into the problem of fusing the characterization of the non-linear continuous medium structure characteristics and plane zoning above the water table with the longitudinal step-by-step characterization of the layered medium structure characteristics below the water table, and lays a structural model foundation for the problems of near-surface structure investigation and characterization in the desert area.

[0217] 2) Provided a method, method idea and technological process for step-by-step characterization of the near-surface structure in desert areas.

[0218] Provided an asymptotic characterization method, theoretical formula for longitudinal step-by-step and spatial partition fusion of the near-surface two-phase medium structure in desert areas, achieving a breakthrough in theory and method; meanwhile, research formed a method idea, implementation steps, technological process for step-by-step asymptotic characterization of the near-surface structure in desert areas and extraction and construction of the parameter field of the characteristic function, and formed physical research results such as a method roadmap and a technological process diagram, which can be comprehensively applied to the characterization, parameter calculation and parameter field construction of near-surface structure characteristic parameters (velocity, thickness, density, Q, static correction amount, etc.) in desert areas, achieving a breakthrough in scientific methods and laying a foundation for industrial implementation;

[0219] 3) Provided a method for characterizing the distribution of near-surface structure characteristic parameters in desert areas.

[0220] Provided a method for fusing the longitudinal step-by-step asymptotic characterization method and the transverse partition characterization method of the near-surface structure in desert areas to construct the characteristic function and characteristic parameter field of the near-surface two-phase medium structure, and for the first time realized the scientific and technological innovation of characterizing the near-surface structure characteristic parameters in desert areas and influencing correction by the "step-by-step calculation and field construction one-step correction method" and the "step-by-step asymptotic field construction correction method", effectively improving the scientific nature of the method for characterizing and correcting near-surface structure characteristic parameters in desert areas and the field construction accuracy. The main method innovations:

[0221] ① A method for segmental fusion characterization of the characteristic curve of micro-logging data of the near-surface structure in desert areas.

[0222] ② First, a method for power function segmental characterization of the characteristic curve and fusion method of the power function characteristic function of adjacent characterization segments of the non-uniform continuous medium structure (sand dune or low velocity reduction zone) overlying the water table in the micro-logging data of the near-surface structure in desert areas; second, a method for segmental characterization of the Q-depth relationship based on micro-logging data, using a power function (Q(H) = A × Hβ) and constant segmental characterization of the Q-value characteristics of the low velocity reduction layer and the high velocity layer.

[0223] ③ A method for transverse characteristic parameter partition, classification and step-by-step characterization of the near-surface structure in desert areas.

[0224] First, a method for transverse characterization and correction of the characteristic parameters (sand parameter) of sand dunes. Creatively proposed the "sand parameter" characteristics and partition, classification and characterization method of sand dunes (low velocity reduction zone), realizing the innovation of the method idea and method; second, a "statistical interpolation method" for transverse characterization of the characteristic parameters of the layered medium structure of the high velocity layer. Thus, a step-by-step characterization method is constructed by fusing the transverse "sand parameter" characteristic parameter partition, classification and characterization method and the "statistical interpolation method" for transverse characterization of the characteristic parameters of the layered medium structure in the near-surface structure of desert areas.

[0225] 4) Method for stepwise extraction and correction of absorption attenuation parameters of near-surface structure in desert area.

[0226] A non-linear characterization method for the low-velocity zone (sand dunes) of the near-surface structure in the desert area and a method for constructing a partitioned power function fitting Q-field, a method for quickly compensating for absorption attenuation in the low-velocity layer to basically eliminate the influence of sand dunes, a method for constructing a high-velocity layer statistical interpolation field, a method for constructing and correcting a comprehensive Q-field of near-surface absorption attenuation parameters, etc. are provided. These methods effectively solve the problems of characterizing, constructing, and correcting absorption attenuation parameters of the near-surface structure in the desert area, and provide method support for improving the frequency extension and imaging processing quality and resolution ability of seismic exploration in the desert area.

[0227] Based on the same inventive concept, the embodiments of the present application also provide a device for characterizing near-surface seismic parameters in the desert area, which can be used to implement the methods described in the above embodiments, such as the following embodiments. Since the principle of solving problems by the device for characterizing near-surface seismic parameters in the desert area is similar to that of the method for characterizing near-surface seismic parameters in the desert area, the implementation of the device for characterizing near-surface seismic parameters in the desert area can refer to the implementation of the method for characterizing near-surface seismic parameters in the desert area, and the repeated parts will not be described again. Hereinafter, the term "unit" or "module" may be a combination of software and / or hardware that can achieve a predetermined function. Although the systems described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0228] The embodiments of the present invention provide a specific implementation manner of a device for characterizing near-surface seismic parameters in the desert area that can implement the method for characterizing near-surface seismic parameters in the desert area. Refer to Figure 19 , the device for characterizing near-surface seismic parameters in the desert area specifically includes the following:

[0229] The longitudinal distribution unit 10 is configured to divide the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table in the desert area;

[0230] The characteristic function establishment unit 20 is configured to establish a characteristic function of the upper part and a characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure;

[0231] The Q-field characterization unit 30 is configured to establish a Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part.

[0232] In one embodiment, refer to Figure 20 , the characteristic function establishment unit 20 includes:

[0233] The sand dune classification module 201 is configured to classify the upper part to generate multiple sand dune type partitions;

[0234] The characterization function obtaining module 202 is used to obtain the characterization function of each partition in the multiple dune type partitions;

[0235] The model establishment module 203 is used to establish the surface structure model of the upper control points;

[0236] The partition parameter field establishment module 204 is used to establish the characteristic parameter field of each partition based on the characterization function with point control as the constraint condition;

[0237] The upper characteristic function generation module 205 is used to generate the upper characteristic function according to the model and the characteristic parameter field.

[0238] In one embodiment, refer to Figure 21 , the characteristic function establishment unit 20 further includes:

[0239] The seismic record generation module 206 is used to correct the influence of characteristic parameters on the characteristic parameter field to generate a corrected seismic record.

[0240] In one embodiment, refer to Figure 22 , the characteristic function establishment unit 20 further includes:

[0241] The layered model generation module 20a is used to generate the lower layered medium model according to the seismic record and the layered medium structure;

[0242] The layered parameter field obtaining module 20b is used to obtain the characteristic parameter field of the layered medium model by using the first arrival refraction tomography method and / or the first arrival refraction energy attenuation analysis method;

[0243] The lower characteristic function establishment module 20c is used to establish the lower characteristic function according to the characteristic parameter field.

[0244] In one embodiment, refer to Figure 23 , the Q field characterization unit 30 includes:

[0245] The upper Q field establishment module 301 is used to establish the upper Q field according to the upper characteristic function;

[0246] The lower Q field establishment module 302 is used to establish the lower Q field according to the lower characteristic function;

[0247] The Q field characterization function generation module 303 is used to generate the near-surface Q field of the desert area by fusing the upper Q field and the lower Q field.

[0248] As can be seen from the above description, the near-surface seismic parameter characterization device provided by the embodiments of the present invention first obtains seismic data of a target work area; then, preprocesses the seismic data; and finally distributes the preprocessed seismic data to multiple computing servers to perform corresponding calculations on the seismic data. The present invention utilizes a job-based data processing platform in a geophysical exploration software system to distribute the single-machine computing tasks in the original interactive software to multiple computing servers for execution, greatly improving the data processing efficiency in the interactive software, shortening the task cycle, and enhancing the user experience, achieving very good results.

[0249] Embodiments of the present application further provide a specific implementation manner of an electronic device that can implement all the steps in the near-surface seismic parameter characterization method in the desert area in the above embodiments. Refer to Figure 24 , the electronic device specifically includes the following contents:

[0250] A processor 1201, a memory 1202, a communication interface 1203, and a bus 1204;

[0251] Among them, the processor 1201, the memory 1202, and the communication interface 1203 communicate with each other through the bus 1204; the communication interface 1203 is used to implement information transmission between related devices such as a server-side device, a seismic data acquisition device, and a user-side device.

[0252] The processor 1201 is used to call a computer program in the memory 1202. When the processor executes the computer program, all the steps in the near-surface seismic parameter characterization method in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0253] Step 100: Divide the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table in the desert area;

[0254] Step 200: Establish a characteristic function of the upper part and a characteristic function of the lower part, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure;

[0255] Step 300: Establish a Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part.

[0256] Embodiments of the present application also provide a computer-readable storage medium capable of implementing all steps in the near-surface seismic parameter characterization method in the above embodiments. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, all steps in the near-surface seismic parameter characterization method in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0257] Step 100: Divide the desert area into an upper part and a lower part from top to bottom according to the water table of the desert area determined in advance;

[0258] Step 200: Establish a characteristic function of the upper part and a characteristic function of the lower part, where the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure;

[0259] Step 300: Establish a Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part.

[0260] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program type embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiments.

[0261] The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0262] Although the present application provides method operation steps as described in the embodiments or flowcharts, based on routine or non-creative labor, there may be more or fewer operation steps. The order of steps listed in the embodiments is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order shown in the embodiments or the figures or in parallel (for example, in an environment of parallel processors or multithreaded processing).

[0263] For the convenience of description, when describing the above device, various modules are described separately according to their functions. Of course, when implementing the embodiments of this specification, the functions of each module can be implemented in the same or multiple software and / or hardware, or the modules implementing the same function can be implemented by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0264] Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same function. Therefore, such a controller can be regarded as a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or the structures within the hardware component.

[0265] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate computer-implemented processing. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0266] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0267] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0268] Embodiments of this specification can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Embodiments of this specification can also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0269] The various embodiments in this specification are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For related parts, reference can be made to the partial description of the method embodiments. In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0270] The above is only the embodiments of the embodiments of this specification and is not used to limit the embodiments of this specification. For those skilled in the art, the embodiments of this specification can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. A method for characterizing near-surface seismic parameters in desert areas, characterized in that, Including: Dividing the desert area from top to bottom into an upper part and a lower part according to the pre-determined water table in the desert area; Establishing a characteristic function of the upper part and a characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure; Establishing a Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part; The steps for determining the water table include: finding a stratum that is stable throughout the target work area and exhibits regional low-frequency variation characteristics as the water table, that is, the structural interface of the longitudinal two-phase or multi-phase structure characteristics in the desert area; the surface structure above the water table is characterized by non-linear continuous medium structure characteristics, presenting two types of non-linear continuous medium characteristic parameters of aeolian dunes and stable dunes and it is difficult to determine a clear boundary; the surface structure below the water table is characterized by layered medium structure characteristics, presenting two-layer or multi-layer structure characteristics; The establishing the characteristic function of the upper part and the characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure, includes: Realizing the detection of the near-surface structure in the desert area and the characterization of the characteristic function step by step longitudinally and regionally horizontally. Specifically, taking the water table as the boundary, simplifying the problem of characterizing the near-surface structure in the desert area into the solution of the fusion method of characterizing the non-linear continuous medium structure characteristics overlying the water table and the planar regional characterization, and the longitudinal step-by-step progressive characterization problem of characterizing the layered medium structure characteristics underlying the water table; that is, first taking the water table as the bottom boundary of the non-uniform continuous medium structure, and according to the progressive fusion method of longitudinally characterizing the structural characteristics and horizontally characterizing the characteristic function of the planar partition of the non-linear continuous medium theory, constructing a characteristic function that can characterize the non-linear continuous medium structure overlying the water table, and correcting the seismic data according to this characteristic function to eliminate the influence of the dunes overlying the water table on the seismic data; then taking the part that has not been completely corrected as a virtual uniform medium thin layer overlying the layered medium structure, and constructing a layered medium structure system together with the high-velocity layer for research to obtain the characteristic parameter field of the layered medium structure; finally, fusing the characteristic parameters of the near-surface two-phase or multi-phase structure in the desert area constructed step by step to construct the characteristic parameter field of the near-surface structure in the desert area, and respectively carrying out the correction of the influence of the near-surface structure characteristic parameters of the seismic data to eliminate the influence of the near-surface structure in the desert area on the seismic wave field; The establishing the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part, includes: Multiplying the established Q-field of the low-velocity zone and the Q-field of the high-velocity layer by their respective travel time accumulations to obtain a comprehensive Q-field of the near-surface absorption attenuation parameter relative to the reference surface. This Q-field is the total attenuation coefficient of the accumulation or the equivalent Q-field of the surface layer. Using this Q-field for seismic wave absorption compensation processing to obtain seismic data excluding the influence of surface absorption.

2. The method for characterizing near-surface seismic parameters in desert areas according to claim 1, wherein The establishing the characteristic function of the upper part includes: Classifying the upper part to generate multiple dune type partitions; Obtaining the characterization function of each partition in the multiple dune type partitions; Establishing the control point surface structure model of the upper part; Taking point control as a constraint condition, establish the characteristic parameter field of each partition according to the said characterization function; Generate the characteristic function of the upper part according to the said model and the characteristic parameter field.

3. The method for characterizing near-surface seismic parameters in desert areas according to claim 2, wherein The establishment of the characteristic function of the upper part further includes: Perform characteristic parameter influence correction on the characteristic parameter field to generate a corrected seismic record.

4. The method for characterizing near-surface seismic parameters in desert areas according to claim 3, wherein The establishment of the characteristic function of the lower part includes: Generate the layered medium model of the lower part according to the seismic record and the layered medium structure; Use the first arrival refraction tomography method and / or the first arrival refraction energy attenuation analysis method to obtain the characteristic parameter field of the layered medium model; Establish the characteristic function of the lower part according to the characteristic parameter field.

5. The method for characterizing near-surface seismic parameters in desert areas according to claim 1, wherein The establishment of the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part includes: Establish the upper Q-field according to the characteristic function of the upper part; Establish the lower Q-field according to the characteristic function of the lower part; Fuse the upper Q-field and the lower Q-field to generate the near-surface Q-field of the desert area.

6. A near-surface seismic parameter characterization device for desert areas, characterized in that, Includes: A longitudinal distribution unit for dividing the desert area into an upper part and a lower part from top to bottom according to the pre-determined water table of the desert area; A characteristic function establishment unit for establishing the characteristic function of the upper part and the characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure; A Q-field characterization unit for establishing the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part; The steps of determining the water table include: finding a stratum that is stable throughout the target work area and exhibits regional low-frequency variation characteristics as the water table, that is, the structural interface of the longitudinal two-phase or multi-phase structure characteristics in the desert area; the surface structure above the water table is characterized by a non-linear continuous medium structure, presenting two types of non-linear continuous medium characteristic parameters of aeolian dunes and stable dunes and it is difficult to determine a clear demarcation line; the surface structure below the water table is characterized by a layered medium structure, presenting two-layer or multi-layer structure characteristics; The establishment of the characteristic function of the upper part and the characteristic function of the lower part, wherein the upper part is a non-linear continuous medium structure; the lower part is a layered medium structure, includes: Implement the detection of the near-surface structure and the characterization of the characteristic function in the desert area step by step longitudinally and regionally horizontally. Specifically, with the water table as the boundary, simplify the problem of characterizing the near-surface structure in the desert area into the solution of the progressive characterization problem of the fusion of the characterization of the nonlinear continuous medium structure overlying the water table and the planar regional characterization method, and the longitudinal step-by-step progressive characterization of the structure characteristics of the layered medium underlying the water table; that is, first take the water table as the bottom boundary of the non-uniform continuous medium structure, and based on the progressive fusion method of the longitudinal structure characterization and the planar regional structure characteristic function characterization of the nonlinear continuous medium theory, construct a characteristic function that can characterize the nonlinear continuous medium structure overlying the water table, and perform correction processing on the seismic data according to this characteristic function to eliminate the influence of the dunes overlying the water table on the seismic data; then regard the part that has not been completely corrected as a virtual homogeneous medium thin layer overlying the layered medium structure, and construct a layered medium structure system together with the high-velocity layer for research, and obtain the characteristic parameter field of the layered medium structure; finally, fuse the characteristic parameters of the near-surface two-phase or multi-phase structure in the desert area constructed step by step to construct the characteristic parameter field of the near-surface structure in the desert area, and separately carry out the correction of the influence of the near-surface structure characteristic parameters of the seismic data to eliminate the influence of the near-surface structure in the desert area on the seismic wave field; The establishment of the Q-field characterization function of the desert area according to the characteristic function of the upper part and the characteristic function of the lower part includes: Multiply the established low-velocity layer Q-field and the high-velocity layer Q-field by their respective travel time accumulations to obtain the comprehensive Q-field of the near-surface absorption attenuation parameters relative to the reference surface. This Q-field is the total attenuation coefficient of the accumulation or the equivalent Q-field of the surface layer. Use this Q-field to perform seismic wave absorption compensation processing to obtain seismic data without the influence of surface absorption.

7. The near-surface seismic parameter characterization device in the desert area according to claim 6, characterized in that, The characteristic function establishment unit includes: The dune classification module is used to classify the upper part to generate multiple dune type partitions; The characterization function calculation module is used to calculate the characterization function of each partition in the multiple dune type partitions; The model establishment module is used to establish the control point surface structure model of the upper part; The partition parameter field establishment module is used to establish the characteristic parameter field of each partition according to the characterization function with point control as the constraint condition; The upper part characteristic function generation module is used to generate the characteristic function of the upper part according to the model and the characteristic parameter field; 8. The near-surface seismic parameter characterization device in the desert area according to claim 7, characterized in that, The characteristic function establishment unit further includes: The seismic record generation module is used to perform correction of the influence of the characteristic parameters on the characteristic parameter field to generate the corrected seismic record; 9. The near-surface seismic parameter characterization device in the desert area according to claim 8, wherein The characteristic function establishment unit further includes: The layered model generation module is used to generate the layered medium model of the lower part according to the seismic record and the layered medium structure; The layered parameter field calculation module is used to calculate the characteristic parameter field of the layered medium model by using the first arrival refraction tomography method and / or the first arrival refraction energy attenuation analysis method; The lower part characteristic function establishment module is used to establish the characteristic function of the lower part according to the characteristic parameter field; 10. The near-surface seismic parameter characterization device in the desert area according to claim 6, wherein The Q-field characterization unit includes: The upper part Q-field establishment module is used to establish the upper part Q-field according to the characteristic function of the upper part; Lower Q - field establishment module, configured to establish the Q - field of the lower part according to the characteristic function of the lower part; Q - field characterization function generation module, configured to generate the near - surface Q - field of the desert area by fusing the Q - field of the upper part and the Q - field of the lower part.

11. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for characterizing near - surface seismic parameters in the desert area according to any one of claims 1 to 5.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for characterizing near - surface seismic parameters in the desert area according to any one of claims 1 to 5.

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