River channel sand group high-resolution seismic sequence division method

Abstract

The invention discloses a high-resolution seismic sequence division method for a river channel sand group, and relates to the technical field of petroleum and natural gas exploration and development. According to the method, a high-resolution sequence stratigraphy theory is taken as guidance, a flooding mudstone interface is taken as a marker bed, a high-density isochronous slice highly matched with seismic data is obtained, and an isochronous stratigraphic interface identification mark is constructed according to sand body development characteristics, so that the multiplicity of solution division of fluvial facies sand group seismic sequences is effectively reduced. According to the method, on the basis of isochronous stratigraphic division, the division scheme is adjusted according to the actual seismic homonymous axis form and the characteristics of the sand body on the well, the unit division result is more objective and fine, and therefore the method can be widely applied to seismic stratigraphic division of the fluvial facies sand group.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration and development, and more specifically to a method for high-resolution seismic sequence division of a river channel sand group. Background Art

[0002] The first step in dividing seismic sequences is to identify the interface that defines the seismic sequence. According to the definition of the sequence, the boundary of the seismic sequence can be understood as the response of an unconformity surface or a comparable conformity surface on the seismic profile. According to the response of geological events on the seismic profile, the relationship between reflection wave groups is divided into two types: coordinated (integrated) relationship and uncoordinated (unified) relationship. The coordinated relationship is equivalent to the conformity contact relationship in geology, and the uncoordinated relationship is equivalent to the unconformity contact relationship in geology.

[0003] Seismic sequence boundaries are identified by analyzing the reflection termination types that characterize inharmonious relationships on seismic sections. The reflection termination types that indicate the bottom interface of a sequence are onlap and downlap, and the reflection types that indicate the top boundary of a sequence are truncation and toplap. Although these signs are well known, they have been given richer connotations in sequence stratigraphy.

[0004] At present, the commonly used fluvial facies stratigraphic division methods are generally based on elevation differences, through the selection of isochronous reference sections, setting vertical sampling intervals, compiling sand body development frequency curves and isochronous stratigraphic interface identification curves from the isochronous reference interface downward, determining isochronous stratigraphic interfaces, and dividing isochronous stratigraphic units. The specific implementation process can be summarized into the following main steps: Step 1: The special reflection wave termination patterns on the seismic section, i.e., top-onlap, truncation, onlap and partial downlap, are used as the main basis for dividing the sequence, taking into account the overall internal reflection characteristics; Step 2: Identify various unconformities and their defined sequences as detailed as possible on the seismic section, and then combine them into higher-level sequences or sequence groups; Step 3: Focusing on the horizontal stacking profile of the backbone network, make full use of the nearby offset profiles and fine processing profiles, and study the wave group characteristics from multiple perspectives, so as to integrate the typical phenomena of different survey lines into the backbone profile as much as possible; Step 4: Use seismic wave groups with prominent features and wide-area traceability to control and improve the reliability of vertical seismic sequence division and horizontal comparison; Step 5: Make full use of the existing VSP data, use VSP as an intermediate medium, establish the connection between seismic profiles and drilling profiles, and analyze and determine the geological attributes of each seismic sequence.

[0005] However, the above method has problems such as poor isochronism of sequence division and mismatch between interface and sand body morphology due to the difference in thickness of sand bodies in a single period of river channel and the accuracy of geophysical exploration. Summary of the invention

[0006] In order to overcome the defects and deficiencies in the above-mentioned prior art, the present invention provides a method for high-resolution seismic sequence division of river channel sand groups. The purpose of the present invention is to accurately identify the spatial distribution law of river channel sand bodies. The present invention is guided by the theory of high-resolution sequence stratigraphy, takes the flood mudstone interface as the marker layer, obtains high-density isochronous slices that are highly matched with seismic data, and constructs isochronous stratigraphic interface identification marks according to the development characteristics of sand bodies, thereby effectively reducing the ambiguity of seismic sequence division of river phase sand groups. On the basis of isochronous stratigraphic division, the present invention adjusts the division scheme according to the actual seismic co-axial morphology and the characteristics of the sand bodies on the well, and the unit division results are more objective and precise. Therefore, the present invention can be widely used in the seismic sequence division of river phase sand groups.

[0007] In order to solve the above problems existing in the prior art, the present invention is implemented through the following technical solutions.

[0008] The present invention provides a method for dividing a channel sandstone group into high-resolution seismic sequences, the method comprising the following steps: S1, Seismic sequence fine calibration step, obtain drilling data, logging data and seismic data in the study area, and perform synthetic record calibration and seismic sequence fine calibration; S2, well-seismic combined sequence division and comparison steps, using standard wells to divide the well logging sequence, based on the theoretical basis of sequence stratigraphy research, on the basis of synthetic record calibration and identification of various formation interfaces, carry out identification and comparison of seismic reflection layers in the sequence formations of connected wells, determine the seismic reflection characteristics and single well sequence division plan; S3, high-resolution sequence stratigraphic modeling step, fault interpretation and stratigraphic interpretation of 3D seismic data, to establish a high-resolution sequence stratigraphic framework model, i.e., isochronous stratigraphic model; on the basis of the isochronous stratigraphic model, according to research needs and interpretation results, the layers of the target layer are extracted to establish high-density isochronous slices of the target layer; S4, high-resolution frequency division sand body identification step under matching pursuit algorithm, select high, medium and low frequencies according to the target layer frequency, use matching pursuit algorithm to obtain high-resolution single-frequency body; perform RGB three-color fusion on the single-frequency body to obtain a set of data bodies sensitive to sand body reflection and frequency division fusion slices based on isochronous stratigraphic model; S5. The step of extracting the interface of the sand layer group under the control of high-density isochronous slices is to comprehensively consider the marker layers with relatively accurate isochronous properties, set the top and bottom windows of the target layer on the basis of the global sequence framework, and make a high-density stratigraphic stack; on the high-density isochronous stratigraphic slices, use the single-frequency body of the matching pursuit method and other data bodies representing the plane distribution of the sand body as input to extract various attribute planes, and determine the top and bottom isochronous surfaces of the channel according to the seismic response characteristics of the channel sand body and the order of appearance of the channel shape shown by the channel on the attribute slice plane, and extract a series of high-density isochronous sequence interpretation horizons to form the stratigraphic interface of the sand layer group.

[0009] Further preferably, in step S1, when performing synthetic record calibration, acoustic wave synthetic record calibration is adopted, and the acoustic wave synthetic record calibration is performed according to set principles, wherein the set principles include extracting seismic traces along the trajectory, estimating wavelets from well side traces, giving priority to strong phases, and jointly comparing and calibrating the main survey line and the tie line.

[0010] More preferably, when calibrating the synthetic records, attention is paid to the marker features of the sequence interface and the reflection features of the sand layer group, so that the wave group features of the synthetic seismic record are close to the seismic wave group reflection of the well bypass, ensuring the correct association between the logging data and the seismic data.

[0011] Further preferably, in step S1, before the synthetic record calibration is performed, the well logging curve is evaluated, quality controlled, edited, corrected and reconstructed.

[0012] More preferably, the correction method of the logging curve includes manual editing, filtering processing or correction processing, wherein the manual editing refers to correcting the abnormal values ​​in the curve point by point, adding a constant value to the amplitude of a certain depth section or the entire well section of the curve, and multiplying the amplitude of a given depth section by the constant value; The filtering process refers to eliminating singular points in the curve by using median filtering and bandpass filtering to achieve the purpose of smoothing the curve; The correction process refers to calculating the error using the seismic logging data and the overall sonic logging data, and then obtaining the error curve, and then correcting the original sonic logging curve with the error curve.

[0013] Further preferably, in step S1, during the fine calibration of the seismic sequence, the frequency of the seismic wavelet is determined by the frequency and bandwidth of the near-well seismic record, and the phase of the seismic wavelet is related to the source and the resolution of the earthquake.

[0014] More preferably, the dominant frequency of the seismic trace data around the well is analyzed to determine the frequency of the seismic wavelet, and then the zero-phase seismic wavelet is selected, and finally the synthetic record is optimally matched with the seismic trace by adjusting the dominant frequency and phase of the seismic wavelet.

[0015] Further preferably, in step S2, global model-controlled structural modeling technology is used to interpret the seismic reflection interface, finely interpret the faults, and identify and carve the sand bodies in the study area.

[0016] More preferably, in step S2, based on the theoretical foundation of sequence stratigraphy research, on the basis of synthetic record calibration and identification of each formation interface, identification and comparison of seismic reflection layers of connected well sequence strata are carried out to determine the seismic reflection characteristics and the single well sequence division scheme, specifically, firstly, a skeleton connected well stratigraphic comparison profile is established on the basis of standard well sequence division; secondly, the seismic reflection interface that can be continuously compared and traced is determined, and a connected well seismic framework profile is established.

[0017] Further preferably, in step S3, a high-resolution sequence stratigraphic framework model is established, which specifically means that on the basis of the interpretation of faults and skeleton profile stratigraphic levels, based on the cost function of seismic data similarity and geological consistency, the seismic data body is spatially deconstructed based on the global optimal method, the optimal structure is selected from a large number of possible sequence stratigraphic frameworks, and the seismic sequence stratigraphic framework model is established directly from the seismic data for stratigraphic tracing and interpretation.

[0018] Further preferably, a model facet grid is first established, and the facets formed by the local trace data within the step definition are regarded as the most basic object units; the interconnection of facet points is based on a cost function of seismic data similarity and geological consistency, and the seismic data body is spatially deconstructed based on a global optimal method, and the optimal structure is selected from a large number of possible stratigraphic frameworks. On the basis of considering seismic reflection characteristics, global consistency of stratigraphic deposition, sedimentary thickness, seismic and geological comprehensive factors of stratigraphic inheritance, a global thinking mode is adopted to consider the entire three-dimensional seismic data body as a whole, and the interpretation scheme and interpretation mode are based on the seismic and geological information contained in the entire three-dimensional data body, accurately establish a relative isochronous framework model, and automatically complete the stratigraphic tracking interpretation; the same geological age values ​​are connected to obtain an isochronous layer, and countless isochronous layers are stacked to form an isochronous stratigraphic model.

[0019] Further preferably, in step S5, on the high-density isochronous stratigraphic slices, the single-frequency body and other result data bodies obtained by spectral decomposition using the matching pursuit method are used as input to extract various attribute planes, and the top and bottom isochronous surfaces of the channel are determined according to the seismic response characteristics of the "top valley and bottom peak" of the channel sand body shown by the channel on the attribute slice plane and the order of appearance of the channel shape, and the attribute body of the single-period channel in the time window is extracted, thereby characterizing the lateral distribution and longitudinal superposition relationship of the river channels of each period.

[0020] Compared with the prior art, the beneficial technical effects brought by the present invention are as follows: 1. The present invention is guided by the theory of high-resolution sequence stratigraphy, takes the flood mudstone interface as the marker layer, obtains high-density isochronous slices that are highly matched with seismic data, and constructs isochronous stratigraphic interface identification marks according to the sand body development characteristics, thereby effectively reducing the ambiguity of seismic stratigraphic sequence division of fluvial facies sand groups. On the basis of isochronous stratigraphic division, the present invention adjusts the division scheme according to the actual seismic symmetric axis morphology and the sand body characteristics on the well, and the unit division result is more objective and precise, so the present invention can be widely used in the seismic stratigraphic sequence division of fluvial facies sand groups.

[0021] 2. The high-resolution seismic sequence division method of the river channel sand group of the present invention can accurately reflect the continuous, stable and locally thickened sedimentary characteristics of the Shaximiao Formation strata. The arbitrary subdivision layer positions extracted from the seismic sequence stratigraphic framework model match well with the seismic reflection characteristics. The attributes extracted along the isochronous stratigraphic slices are combined with the RGB attribute fusion to identify 23 phases of sand layer groups in the Shaximiao Formation, realizing the comparability of the sand layer groups and rivers of the Shaximiao Formation in the whole region in Sichuan, filling the technical gap in this field. This method is applicable to most areas of the Sichuan Basin, and can double the work efficiency, reducing the research cycle to at least 1 / 8.

[0022] 3. The advantage of the present invention is that high-density isochronous slices that match the seismic height are established through automatic tracking technology on the basis of conventional methods to perform high-resolution seismic sequence division of sand groups. The isochronism, accuracy and work efficiency of the division scheme are all higher than those of conventional methods.

[0023] 4. To complete the fine calibration of regional layers and reservoirs, the present invention first completes the processing flow of evaluation, quality control, editing, correction and reconstruction of the logging curve. The curve correction method of the present invention makes the corrected logging curve closer to the actual curve, providing reliable basic data for accurate calibration.

[0024] 5. In the process of fine calibration of seismic sequences of the present invention, the frequency of the seismic wavelet is determined by the frequency and bandwidth of the wellside seismic record, and the phase of the seismic wavelet is related to the source and the resolution of the earthquake. This can achieve reliable fine calibration of the horizon and accurately obtain the frequency and phase of the seismic wavelet. From the fine well-seismic calibration of 164 wells, the present invention shows that the synthetic record trace calculated by the corrected acoustic wave density curve is almost consistent with the seismic reflection characteristics of each marker layer, and the wave group characteristics of the synthetic seismic record are similar to the seismic wave group reflection of the wellside trace, which proves the accuracy of the synthetic record production process.

[0025] 6. The present invention adopts global model-controlled structural modeling technology to complete the interpretation of reflection interfaces, detailed interpretation of faults, and identification and carving of sand bodies in the research area. It has good applicability in the identification and carving of sand bodies in the Shaximiao Formation. The applicant also used global model-controlled structural modeling technology to complete the detailed interpretation of the main seismic reflection interfaces and faults of the Shaximiao and Xujiahe Formations in the Jinhua-Xichong area.

[0026] 7. The seismic sequence stratigraphic framework model constructed by the present invention accurately reflects the continuous, stable and locally thickened sedimentary characteristics of the Shaximiao Formation. The arbitrary subdivided layers extracted from the seismic sequence stratigraphic framework model match well with the seismic reflection characteristics, providing a solid foundation for the subsequent extraction of along-layer and inter-layer attributes.

[0027] 8. Based on the interpretation of fault and skeleton profile layers, the present invention uses a cost function based on seismic data similarity and geological consistency, and uses the idea of ​​global optimization methods to spatially deconstruct the seismic data body, select the optimal structure from a large number of possible stratigraphic frameworks, and directly establish a seismic stratigraphic framework model from the seismic data to automatically complete the layer tracking interpretation. This seismic interpretation method completely subverts the traditional seismic interpretation method of first picking up a limited number of layers and then establishing a seismic stratigraphic framework model. Instead, it is completely the other way around, first establishing a seismic stratigraphic framework model, and then extracting the layers of the target layers as needed. The layers extracted based on the seismic stratigraphic framework model are more accurate than those obtained by traditional interpretation. At the same time, the cross-axis, jump point, and non-closure phenomena that exist in the traditional layer interpretation results are basically non-existent in the extraction results of the new method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of the high-resolution seismic sequence division method for the channel sand group; Figure 2 To calibrate the synthetic record of the river sand formation in the study area; Figure 3 It is the sequence division and comparison diagram of well-seismic combination; Figure 4 It is a three-dimensional structural diagram of the seismic sequence stratigraphic framework model; Figure 5 This is a schematic diagram of seismic wavelet decomposition; Figure 6 This is a comparison chart of the results of conventional frequency division and MPD frequency division; Figure 7 This is a single well sand body logging response characteristic analysis diagram; Figure 8 This is the characteristic diagram of the sand body joint response to well-seismic; Fig. 9 This is a statistical result diagram of the unified division of sand layer sequences in the contiguous work area. DETAILED DESCRIPTION

[0029] The following is an exemplary embodiment of the present invention that helps to fully understand the claims and their equivalents in conjunction with the accompanying drawings, wherein the specific details will be considered as exemplary only, and do not limit the scope of the present invention. Therefore, those of ordinary skill in the art can make various changes and modifications to the embodiments without departing from the scope and spirit of the present invention.

[0030] Example 1 As a preferred embodiment of the present invention, this embodiment takes Shaximiao gas reservoir as an example to further elaborate the technical solution of the present invention.

[0031] The Shaximiao gas reservoir is a shallow fluvial dense sandstone gas reservoir, which is a typical clastic rock low-porosity and low-permeability gas reservoir. The sand reservoir is unevenly distributed, with multiple productive layers in the vertical direction and poor continuity in the horizontal direction. It is obviously controlled by local and regional structures. The strong heterogeneity has brought great difficulties to the exploration and development of the gas reservoir, which is also a thorny problem faced by the development of the gas reservoir so far. Due to the frequent changes in the river channel of the Shaximiao Formation in central Sichuan, the river channel sand has the characteristics of small single-layer thickness, small single sand body volume and rapid lateral changes. In order to accurately identify the spatial distribution law of the river channel sand body, a high-resolution seismic sequence division method for the river channel sand formation was established. Step 1: Make a fine calibration of the seismic sequence. When calibrating the Shaximiao Formation, attention should be paid to both the marking characteristics of the sequence interface and the reflection characteristics of the sand layer group, so that the wave group characteristics of the synthetic seismic record are close to the seismic wave group reflection of the well bypass, and the logging data and seismic data are correctly associated (see the attached manual). Figure 2 as shown).

[0032] Step 2: Carry out well-seismic sequence division and comparison work, use standard wells to divide the logging sequence, based on the theoretical basis of sequence stratigraphy research, on the basis of synthetic record calibration and identification of various formation interfaces, carry out identification and comparison of seismic reflection layers in the sequence strata of connected wells, determine the seismic reflection characteristics and the single well sequence division plan (as shown in the attached manual Figure 3 shown.

[0033] Step 3: Establish a high-resolution sequence stratigraphic model. Use PaleoScan software to interpret the faults and stratigraphic interpretation of the 3D seismic data and establish a high-resolution sequence stratigraphic framework model, i.e., an isochronous stratigraphic model. On this basis, combined with the interpretation results, establish a high-density isochronous slice of the target layer (see the attached manual). Figure 4 as shown).

[0034] Step 4: Select appropriate high, medium and low frequencies for the target layer frequency, and use the matching pursuit algorithm to obtain a high-resolution single-frequency body. Perform RGB three-color fusion on the single-frequency body to obtain a set of data bodies sensitive to sand body reflection and frequency-divided fusion slices based on the isochronous stratigraphic model (see the attached manual). Figure 5 and attached Figure 6 as shown).

[0035] Step 5: Comprehensively consider the marker layers with relatively accurate isochronism, set the top and bottom windows of the target layers on the basis of the global sequence framework, and make high-density stratigraphic stacks. On the high-density isochronous stratigraphic slices, use the single-frequency body of the matching pursuit method and other data bodies representing the plane distribution of the sand body as input to extract various attribute planes. According to the seismic response characteristics of the river channel sand body and the order of appearance of the river channel shape shown by the river channel on the attribute slice plane, the top and bottom isochronous surfaces of the river channel are determined, and a series of high-density isochronous sequence interpretation horizons are extracted to form the stratigraphic interface of the sand layer group (as shown in the attached manual). Figure 7 and attached Figure 8 as shown).

[0036] This high-resolution seismic sequence division method for channel sandstone formations can accurately reflect the continuous, stable, and locally thickened sedimentary characteristics of the Shaximiao Formation. The arbitrary subdivision layers extracted from the seismic sequence stratigraphic framework model match well with the seismic reflection characteristics. The attributes extracted along the isochronous stratigraphic slices were combined with the RGB attribute fusion to identify 23 sandstone formations in the Shaximiao Formation, achieving the comparability of sandstone formations and river channels of the Shaximiao Formation in central Sichuan throughout the region, filling the technical gap in this field. This method is applicable to most areas of the Sichuan Basin, and can double the work efficiency, reducing the research cycle to at least 1 / 8 (as shown in the attached manual). Fig. 9 as shown).

[0037] Example 2 As another preferred embodiment of the present invention, refer to the attached specification Figure 1 As shown, this embodiment discloses a method for high-resolution seismic sequence division of a river channel sand group, the method comprising the following steps: S1, Seismic sequence fine calibration step, obtain drilling data, logging data and seismic data in the study area, and perform synthetic record calibration and seismic sequence fine calibration; S2, well-seismic combined sequence division and comparison steps, using standard wells to divide the well logging sequence, based on the theoretical basis of sequence stratigraphy research, on the basis of synthetic record calibration and identification of various formation interfaces, carry out identification and comparison of seismic reflection layers in the sequence formations of connected wells, determine the seismic reflection characteristics and single well sequence division plan; S3, high-resolution sequence stratigraphic modeling step, fault interpretation and stratigraphic interpretation of 3D seismic data, to establish a high-resolution sequence stratigraphic framework model, i.e., isochronous stratigraphic model; on this basis, combined with the interpretation results and according to the research needs, the layers of the target layer are extracted to establish high-density isochronous slices of the target layer; S4, high-resolution frequency division sand body identification step under matching pursuit algorithm, select high, medium and low frequencies according to the target layer frequency, use matching pursuit algorithm to obtain high-resolution single-frequency body; perform RGB three-color fusion on the single-frequency body to obtain a set of data bodies sensitive to sand body reflection and frequency division fusion slices based on isochronous model and isochronous stratigraphic model; S5. The step of extracting the interface of the sand layer group under the control of high-density isochronous slices is to comprehensively consider the marker layers with relatively accurate isochronous properties, set the top and bottom windows of the target layer on the basis of the global sequence framework, and make a high-density stratigraphic stack; on the high-density isochronous stratigraphic slices, use the single-frequency body of the matching pursuit method and other data bodies representing the plane distribution of the sand body as input to extract various attribute planes, and determine the top and bottom isochronous surfaces of the channel according to the seismic response characteristics of the channel sand body and the order of appearance of the channel shape shown by the channel on the attribute slice plane, and extract a series of high-density isochronous sequence interpretation horizons to form the stratigraphic interface of the sand layer group.

[0038] As an implementation method of this embodiment, in step S1, when performing synthetic record calibration, acoustic wave synthetic record calibration is adopted, and the acoustic wave synthetic record calibration is performed according to set principles, and the set principles include extracting seismic traces along the trajectory, estimating sub-waves of well side traces, strong phase priority, and joint comparison calibration of main survey lines and connecting lines.

[0039] Furthermore, when calibrating synthetic records, attention should be paid to the marker features of the sequence interface and the reflection features of the sand layer group, so that the wave group features of the synthetic seismic record are close to the seismic wave group reflection of the well bypass, ensuring the correct association of the logging data with the seismic data.

[0040] As another implementation of this embodiment, in step S1, before the synthetic record calibration is performed, the logging curve is evaluated, quality controlled, edited, corrected and reconstructed. The correction method of the logging curve includes manual editing, filtering processing or correction processing, wherein the manual editing refers to correcting the abnormal values ​​in the curve point by point, adding a constant value to the amplitude of a certain depth segment or the entire well segment of the curve, and multiplying the amplitude of a given depth segment by a constant value; The filtering process refers to eliminating singular points in the curve by using median filtering and bandpass filtering to achieve the purpose of smoothing the curve; The correction process refers to calculating the error using the seismic logging data and the overall sonic logging data, and then obtaining the error curve, and then correcting the original sonic logging curve with the error curve.

[0041] As another implementation of this embodiment, in step S1, during the fine calibration of the seismic sequence, the frequency of the seismic wavelet is determined by the frequency and bandwidth of the seismic record near the well, and the phase of the seismic wavelet is related to the resolution of the earthquake source and the earthquake. The main frequency of the seismic trace data around the well is analyzed to determine the frequency of the seismic wavelet, and then the zero-phase seismic wavelet is selected, and finally the main frequency and phase of the seismic wavelet are adjusted to achieve the best match between the synthetic record and the seismic trace.

[0042] Example 3 As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and elaboration of the technical solution of the present invention based on the above-mentioned embodiment 1 or embodiment 2. In this embodiment, in step S2, the global model-controlled structural modeling technology is used to interpret the seismic reflection interface of the research area, fine interpretation of faults, and identification and carving of sand bodies.

[0043] Furthermore, in step S2, based on the theoretical foundation of sequence stratigraphy research, on the basis of synthetic record calibration and identification of each formation interface, identification and comparison of seismic reflection layers in connected well sequence strata are carried out to determine the seismic reflection characteristics and the single well sequence division scheme. Specifically, first, a skeleton connected well stratigraphic comparison profile is established on the basis of standard well sequence division; secondly, the seismic reflection interface that can be continuously compared and traced is determined to establish a connected well seismic framework profile.

[0044] Example 4 As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and elaboration of the technical solution of the present invention based on the above-mentioned embodiment 1, embodiment 2 or embodiment 3. In this embodiment, in step S3, a high-resolution sequence stratigraphic framework model is established, which specifically refers to that on the basis of the interpretation of the fault and skeleton profile horizon, based on the cost function of seismic data similarity and geological consistency, the seismic data body is spatially deconstructed based on the global optimal method, the optimal structure is selected from a large number of possible sequence stratigraphic frameworks, and the seismic sequence stratigraphic framework model is directly established from the seismic data to perform horizon tracking interpretation.

[0045] First, a model facet grid is established, and the facets formed by the local trace data within the step definition are regarded as the most basic object units; the interconnection of facet points is based on the cost function of seismic data similarity and geological consistency, and the seismic data body is spatially deconstructed based on the global optimal method, and the optimal structure is selected from a large number of possible stratigraphic frameworks. On the basis of considering seismic reflection characteristics, global consistency of stratigraphic deposition, sedimentary thickness, seismic and geological comprehensive factors of stratigraphic inheritance, a global thinking mode is adopted to consider the entire three-dimensional seismic data body as a whole. The interpretation scheme and interpretation mode are based on the seismic and geological information contained in the entire three-dimensional data body, and a relative isochronous framework model is accurately established to automatically complete the stratigraphic tracking interpretation; the same geological age values ​​are connected to obtain an isochronous layer, and countless isochronous layers are stacked to form an isochronous stratigraphic model.

[0046] In step S5, on the high-density isochronous stratigraphic slices, the single-frequency body and other result data bodies obtained by spectral decomposition using the matching pursuit method are used as input to extract various attribute planes. According to the seismic response characteristics of the "top valley bottom peak" of the channel sand body shown in the channel on the attribute slice plane and the order of appearance of the channel shape, the top and bottom isochronous surfaces of the channel are determined, and the attribute body of the single-period channel in the time window is extracted, thereby characterizing the lateral distribution and longitudinal superposition relationship of the river channels of each period.

[0047] Example 5 As another preferred embodiment of the present invention, this embodiment takes the stratigraphic division of river channel sand layers in a certain area of ​​Sichuan Basin as an example to illustrate the specific scheme of the present invention.

[0048] Step 1: Fine calibration of seismic sequences (synthetic records) Synthetic record calibration is the basic work of seismic interpretation. It is to organically combine drilling data, logging data and seismic data to establish a bridge for the corresponding relationship between lithology, electrical properties, physical properties and wellside seismic traces. The main methods of layer calibration are VSP calibration, acoustic synthetic seismic record calibration and comprehensive velocity calibration. Among them, acoustic synthetic seismic record calibration is one of the most commonly used means of layer calibration in the process of seismic interpretation. In the calibration process, make full use of the full-well logging curve to calibrate the main marker layer of the whole well section. If there is a density curve in the drilling, use the density curve. Follow the following principles of acoustic synthetic record calibration: extract seismic traces along the trajectory as much as possible; estimate sub-waves of wellside traces; give priority to strong phases; and calibrate the main survey line and the connecting line by joint comparison.

[0049] In order to complete the fine calibration of regional formations and reservoirs, we first completed the processing procedures of evaluation, quality control, editing and reconstruction of the logging curves.

[0050] There are many factors that affect the logging curve, such as drilling mud type, well inclination, caliper logging instrument, lifting speed, immersion time, etc. Of course, the current acoustic logging mostly uses long source distance and compensated acoustic logging methods, plus the post-environmental correction and compensation processing, the data accuracy should be guaranteed. However, before loading the data into the computer, other logging curves and well logging diagrams should still be referred to, and the acoustic and density logging curves should be analyzed and studied.

[0051] Common logging curve correction methods include manual editing, filtering, and correction. ① Manual editing, that is, correcting the abnormal values ​​in the curve point by point, adding a constant value to the amplitude of a certain depth section or the entire well section of the curve, multiplying the amplitude value of a given depth section by a constant value, etc.; ② Filtering, that is, using median filtering and bandpass filtering methods to eliminate singular points in the curve to achieve the purpose of smoothing the curve; ③ Correction, that is, using seismic logging data and overall acoustic logging data to calculate errors, and after obtaining the error curve, the original acoustic logging curve is corrected by this error curve. The above curve correction methods make the corrected logging curve closer to the actual curve, providing reliable basic data for accurate calibration.

[0052] In order to achieve reliable and precise calibration of the horizon, the frequency and phase of the seismic wavelet must be accurately obtained. The frequency of the seismic wavelet is determined by the frequency and bandwidth of the seismic record near the well. The phase of the seismic wavelet is related to the source and the resolution of the earthquake. The process is as follows: First, the main frequency of the seismic trace data around the well is analyzed to determine the frequency of the wavelet; then the zero-phase wavelet is selected; finally, the main frequency and phase of the wavelet are adjusted to achieve the best match between the synthetic record and the seismic trace.

[0053] From the fine well-seismic calibration of 164 wells, it can be seen that the synthetic record traces calculated using the corrected acoustic wave density curves are almost consistent with the seismic reflection characteristics of each marker layer, and the wave group characteristics of the synthetic seismic record are similar to the seismic wave group reflections of the wellside traces, which proves the accuracy of the synthetic record production process.

[0054] Step 2: Sequence division and comparison based on well-seismic combination In order to build an accurate geological model, seismic interpreters must have a clear understanding of the structural information in the seismic data, especially the fault information. Traditionally, this is achieved by manually picking faults on the seismic data, which is a tedious and time-consuming task. Therefore, great efforts have been made in the past two decades to improve the efficiency of fault interpretation and realize automatic fault detection. At present, seismic attributes such as coherence, variance and chaos have been used to capture the fault location, but the results are limited due to the influence of the inhomogeneity of the seismic signal near the fault on the attribute value. The seismic data in this area are of good quality and have strong lateral comparability. Therefore, the global model-controlled structural modeling technology is used to complete the interpretation of the seismic reflection interface of the Shaximiao Formation, the fine interpretation of faults, and the identification and carving of sand bodies.

[0055] The global controlled structural modeling technology is very applicable to the identification and carving of sand bodies in the Shaximiao Formation. This time, the global controlled structural modeling technology was used to complete the detailed interpretation of the main seismic reflection interfaces and faults of the Shaximiao and Xujiahe Formations in the Jinhua-Xichong area.

[0056] The logging sequence was divided using standard wells, and the first section of the Shah was divided into a complete four-level cycle. The bottom of the first section of the Shah is a set of gray and gray-green mudstones, which transform upward into purple-red mudstones, representing the transition of the sedimentary environment from a reducing environment to an oxidizing environment. At the same time, the mud content gradually decreases and the sand content increases upward. The overall performance is a descending cycle with shallower water bodies. The AC value of the entire Shah II 1 decreases from bottom to top, the RT value increases, and the GR decreases. The overall performance is a decline in the water body, which is a descending half-cycle four-level sequence. The AC value at the top of Shah II 1 is the smallest. After the GR value is the smallest, the water body rises upward, the overall accommodative space increases, and the mud deposition increases. Until the GR value at the top of the third sublayer of the second section of the Shaximiao Formation reaches the maximum, the maximum flooding surface is reached and the accommodative space reaches the maximum. The second section of the Shaximiao Formation, the fourth sublayer, is a descending half-cycle as a whole, with a decrease in accommodative space and a gradual increase in sand content.

[0057] Based on the theoretical foundation of sequence stratigraphy research, on the basis of synthetic record calibration and identification of each stratigraphic interface, the seismic reflection layer identification and comparison of well-connected sequence stratigraphy were carried out, and the seismic reflection characteristics and single well sequence division scheme were integrated. First, the skeleton well-connected stratigraphic comparison section was established on the basis of the standard well sequence division, and the well-seismic combination was used to divide the four sub-sections of the second section of the Shaxi Miao Formation and the first section of the Shaxi Miao Formation into well logging sequences and seismic sequences. Secondly, the continuous and traceable seismic reflection interface was determined for model establishment. There are 4 seismic reflection interfaces with clear characteristics in the Shaxi Miao Formation, namely the bottom of the Shaxi Miao Formation (J2s1), the bottom of the first section of the second section of the Shaxi Miao Formation (J2s21), the bottom of the second section of the second section of the Shaxi Miao Formation (J2s22), and the top of the Shaxi Miao Formation (J3s). The seismic phases above and below the interface are obviously different. In different sequences, the seismic reflection strength on the section changes laterally, reflecting the development of the river channel.

[0058] Through the three-dimensional seismic interpretation profile of Jinhua 6-Jinhua 5-Nanchong 2-Jiao 95 Jiao 38-Zhongtai 2 wells from Jinhua to Xichong and the well-to-well stratigraphic comparison map, the seismic reflection layers of the main reflection layer interfaces in the whole area were identified by combining well-seismic comparison, and the calibration results of the main stratigraphic interfaces are as follows: bottom of Suining Formation - crest, upper bottom of the second submember of Shaximiao Formation - trough, bottom of the second submember of Shaximiao Formation - trough, sand bottom - strong trough, bottom of the fifth section of Xuzhou - strong peak, bottom of the fourth section of Xuzhou - trough, bottom of the third section of Xuzhou - weak peak, upper bottom of the second section of Xuzhou - weak peak, bottom of the second section of Xuzhou - trough, bottom boundary of the first submember of Xujiahe - strong peak.

[0059] Overall, the energy changes of the reflection layers at the bottom of the sand bottom and the first sublayer of the second subsection of the Shaximiao Formation are relatively small, which can be compared, tracked and interpreted; however, the energy changes of the reflection layers at the bottom of the second subsection of the Shaximiao Formation are large, and the continuity of the event axis is relatively poor, which makes it difficult to accurately interpret.

[0060] In view of this, before carrying out the global model-controlled automatic interpretation, combined with the Qiulin 3D and Shehong 3D studies in the previous period, a comprehensive interpretation of multiple skeleton profiles was carried out to ensure the spatial consistency of each seismic reflection layer and lay the foundation for the subsequent full 3D tracking interpretation.

[0061] From the seismic interpretation skeleton profile of Jinhua 6-Jinhua 5-Jinhua 11-Jinhua 31-Jinhua 27-Jinhua 2-Jinhua 3 wells in the Jinhua-Shehong Dalian area, it can be seen that the stratum distribution is relatively stable. From Jinhua to Shehong, the stratum thickness trend of the second subsegment of the Shaximiao Formation remains unchanged. Combined with stratigraphic comparison, the GR-AC curve comparison diagram of the connected wells was established. The change of stratum thickness is consistent with the thickness law of seismic interpretation, and the wells and seismic are unified.

[0062] From the overall seismic interpretation skeleton profile of the Fushun 1-Qiu 3-Qiu Lin 2-Qiu Lin 3-Qiu Lin 6-Nanchong 2 wells in the Qiulin-Bajiaochang Dalian area, it can be seen that the strata are relatively stable. From Qiulin to Zhongtaishan, the strata of the second sub-member of the Shaximiao Formation gradually thicken slightly. Combined with stratigraphic comparison, the establishment of a seismic framework profile of connected wells was carried out. The changes in strata thickness are consistent with the thickness law of seismic interpretation, and the wells and seismic are unified.

[0063] Through the comparison map of the Da'anzhai and Shaximiao stratigraphy of Yanting North-Bajiaochang-Xichong, Jiao 31-Jiao 34-Jiao 98-Jiao 60-Jiao 95-Jiao 96-Jiao 38 wells, it can be seen that the stratigraphic distribution is relatively stable as a whole. Combined with the stratigraphic comparison, the establishment of a well-connected seismic framework profile was carried out. The changes in stratigraphic thickness are consistent with the thickness law of seismic interpretation, and the wells and seismic are unified.

[0064] The seismic sequence stratigraphic framework model accurately reflects the continuous, stable, and locally thickened sedimentary characteristics of the Shaximiao Formation. The arbitrary subdivided layers extracted from the seismic sequence stratigraphic framework model match well with the seismic reflection characteristics, providing a solid foundation for the subsequent extraction of along-layer and inter-layer attributes.

[0065] Step 3: High-resolution sequence stratigraphic modeling Based on the interpretation of fault and skeleton profile stratigraphic layers, this study uses the cost function of seismic data similarity and geological consistency, and uses the idea of ​​global optimization methods to spatially deconstruct the seismic data body, select the optimal structure from a large number of possible stratigraphic frameworks, and directly establish a seismic stratigraphic framework model from the seismic data to automatically complete the stratigraphic tracking interpretation. This seismic interpretation method completely subverts the traditional seismic interpretation method of first picking up a limited number of layers and then establishing a seismic stratigraphic framework model. Instead, it is completely the other way around, first establishing a seismic stratigraphic framework model, and then extracting the target layer layers as needed. The layers extracted based on the seismic stratigraphic framework model are more accurate than those obtained by traditional interpretation. At the same time, the cross-axis, jump point, and non-closure phenomena that exist in the traditional stratigraphic interpretation results are basically non-existent in the results extracted by the new method.

[0066] The specific implementation process first requires the establishment of a seismic-based stratigraphic model, and first establishes the model surface element grid. The patch (surface element) formed by the local trace data within the step definition is regarded as the most basic object unit. This approach elevates our way of thinking from section to section in three-dimensional space, and becomes a real explanation from a three-dimensional perspective.

[0067] Secondly, we usually make a connection judgment based on the "similar" characteristics of the waveform reflections of the two phase axis data. And this "similarity" is not a simple correlation, but a comprehensive judgment based on the reflection characteristics of adjacent wave groups, the reflection trend of the stratum, and other information.

[0068] In the sequence stratigraphic model, the interconnection of facet points is based on the cost function of seismic data similarity and geological consistency. The seismic data body is spatially deconstructed based on the idea of ​​global optimization method, and the optimal structure is selected from a large number of possible sequence stratigraphic frameworks. While considering seismic reflection characteristics, global consistency of stratigraphic deposition, sedimentary thickness, stratigraphic inheritance and other seismic and geological comprehensive factors, the "global thinking" mode is adopted to consider the entire three-dimensional seismic data body as a whole. The interpretation plan and interpretation mode are based on the seismic and geological information contained in the entire three-dimensional data body, accurately establish a relative isochronous framework model, and automatically complete the stratigraphic tracking interpretation.

[0069] The establishment of a three-dimensional stratigraphic model is actually to connect patches with the same relative geological age into layers. After having a stratigraphic framework based on the reflection of the same phase axis, the three-dimensional stratigraphic model (stacked body of stratigraphic layers) is refined and interpolated according to the inheritance of stratigraphic deposition.

[0070] By connecting the same geological age values, we get an isochronous (equal relative geological age) layer. Therefore, the isochronous stratigraphic model is actually a stack of countless isochronous layers.

[0071] This seismic interpretation method completely subverts the traditional seismic interpretation method of first picking up a limited number of layers and then establishing a seismic sequence stratigraphic framework model. Instead, it is completely the other way around, first establishing a seismic sequence stratigraphic framework model and then extracting the layers of the target strata as needed.

[0072] Of course, this simulation is not very complete. For complex seismic data, the human brain can refer to information such as sedimentation patterns in neighboring areas, work experience, etc. when making judgments, and this information is information that cannot be considered by the value function of the current software, so this type of algorithm still has a lot of room for improvement. In practical applications, this method is a very convenient and easy-to-use solution. It can quickly add our geological knowledge to the modeling process for guidance and constraints, and integrate human geological knowledge and software efficient calculations, thereby greatly improving the efficiency of seismic interpretation.

[0073] The horizons extracted based on the seismic sequence stratigraphic framework model are more accurate than those obtained by traditional interpretation. At the same time, the cross-axis, jump point and non-closure phenomena existing in the traditional horizon interpretation results are basically non-existent in the results extracted by the new method. Adjustment, establishment and improvement of the seismic sequence stratigraphic framework model for the whole area. The seismic sequence stratigraphic framework model accurately reflects the continuous, stable and locally thickened sedimentary characteristics of the Shaximiao Formation.

[0074] Step 4: High-resolution frequency division sand body identification based on matching pursuit algorithm This time, combined with various logging curves reflecting physical properties of drilling in the study area, an intersection analysis was conducted on the logging response characteristics of each sand body in the vertical direction. The drilling results of each well show that each well has multiple sets of sand bodies developed vertically, with thickness ranging from 5 meters to 17 meters. Each sand body has a large velocity difference. The red sand bodies are relatively high-velocity sand bodies. The sand bodies are relatively dense, and the sand body velocity is significantly higher than that of the surrounding rock. They are developed in a single period or in multiple periods in the vertical direction. The gray marked sand bodies are low-velocity sand bodies with a velocity slightly lower than that of the surrounding rock. They are developed in a single period or superimposed with high-velocity sand bodies.

[0075] On the basis of the analysis of sand body logging response characteristics, the seismic response characteristics of sand bodies were further analyzed in combination with seismic data. The seismic reflection characteristics of sand bodies were confirmed through fine well-seismic calibration. Sand bodies with different physical and electrical properties have different seismic response mode characteristics. The calibration of the seismic synthetic record of Jinhua Well 1 shows that the Shaximiao sand body obviously has three different seismic response modes: Mode 1: low impedance sandstone, with an upper trough and a lower crest in the earthquake, and high porosity; Mode 2: medium impedance sandstone, weak seismic reflection, medium porosity; Mode 3: High impedance sandstone, seismic reflection is upper crest and lower trough, and the porosity is low.

[0076] Sand bodies generally show seismic reflection characteristics of "low frequency, strong amplitude, low impedance, short extension range, and pull-down phenomenon" on seismic profiles. However, it is difficult to determine the specific location of sand bodies with different velocities and impedances. In order to clarify the specific location and reflection characteristics of the box body on the seismic profile, it is necessary to establish the seismic response model of each impedance sand body.

[0077] This time, by conducting 2D seismic forward modeling analysis on sand bodies of different thicknesses, the seismic response mode of the sand bodies in this area was further demonstrated. By analyzing the frequency spectrum distribution law of the second segment of the Shaximiao Formation and combining the velocity of the target layer, the ability of existing seismic data to identify single sand layers and sand layer combinations of different thicknesses was clarified.

[0078] The spectrum analysis of seismic data determined that the main frequency of the target layer of the seismic data was about 36Hz, the layer velocity was 4100m / s, and the seismic tuning thickness of the area was calculated to be about 17-28m. Reservoir models of different thicknesses in the region were established, and regional reservoir forward modeling was performed to determine the specific locations of different reservoir thicknesses in seismic response.

[0079] The results show that when the thickness is less than the tuning thickness, the sand body is between the trough and the crest; when the thickness of the sand body is close to the tuning thickness, the sand body is in the middle of the trough and the crest; when the thickness of the sandstone exceeds the tuning thickness, the sand body is at the outer edge of the trough and the crest. This feature has a good correspondence with the theoretical wedge model.

[0080] Due to the wavelet superposition effect and ringing effect generated by multiple wave impedance interfaces, seismic traces cannot directly reflect the characteristics of interface positions and stratum combinations, and different geological targets have different sensitivities to different frequency components of seismic data. Therefore, using the specific frequency and frequency band information of seismic signals to highlight the imaging effect of seismic targets has always been an important part of geophysical exploration research.

[0081] Spectral decomposition is to decompose a seismic trace into a collection of sub-waves of different shapes (main frequencies) and amplitudes. It is an effective technology to understand geological bodies by using the different response characteristics of different frequencies to geological bodies of different scales, thereby performing seismic interpretation.

[0082] The multi-attribute fusion display technology is to mix and display the energy attributes of the low frequency band (32Hz), medium frequency band (62Hz), and high frequency band (92Hz) in RGB mode to form a color data body. RGB is the most commonly used color mode in the industry, where R represents red, G represents green, and B represents blue. Red, green, and blue are the three most basic colors. The rich and colorful colors in nature are all obtained by superimposing and mixing these three primary colors.

[0083] RGB images use only three colors, and can mix them in different proportions to reproduce up to 160,000 colors on the screen. In RGB mode, each RGB component can use a value from 0 (black) to 255 (white). When all three component values ​​are equal, a shade of gray is produced. When the value of all components is 255, the result is pure white; when the value is 0, the result is pure black.

[0084] In the three primary colors, when Red and Green are mixed, the R value is 255, the G value is 255, and the B value is 0, and the mixed color is Yellow. When Blue and Red are mixed, the R value is 0, the G value is 255, and the B value is 255, and the mixed color is Magenta. When all three are at their maximum values, that is, when R=G=B=255, the result is white.

[0085] Similarly, the RGB mixed mode is introduced into the seismic frequency division attribute analysis, and the energy attribute bodies of the three non-overlapping frequency bands are mixed and displayed in RGB mode to form an RGB mixed frequency data body with frequency information. In practical applications, the low-frequency band energy attribute is selected as red (R), the mid-frequency band energy attribute is selected as green (G), and the high-frequency band energy attribute is selected as blue (B).

[0086] First, the energy of each attribute body is normalized so that the energy of each body has a completely consistent dynamic range, that is, it is standardized to a color intensity value within the range of 0~255. Among them, 0 is the smallest attribute value, which is black; 255 is the largest attribute value, which is a pure color, such as red. Then these three attribute bodies are mixed with RGB colors. At this time, each sampling point obtains a composite color, and the composite color is related to the proportion of each body at this point. If all three are pure colors at this point (that is, the energy attribute values ​​are all maximum), the point will appear white after mixing; if the low-frequency band R and the mid-frequency band G are all pure colors (that is, the energy attribute values ​​are all maximum), and the high-frequency band is black (the energy attribute value is the minimum), the point will appear yellow after mixing.

[0087] This RGB mixed display method has a good effect on highlighting the energy-approximate characteristic areas in each frequency division attribute, which can highlight the commonality and weaken the difference. For geological body identification, if the different frequency band attribute bodies show strong energy characteristics after frequency division, the geological body will be clearly presented as a near-white feature on the color data body after RGB mode mixing, which is obviously different from the surrounding rock; if the geological body also shows weak characteristics on the energy attribute body after frequency division, it is difficult to distinguish its distribution characteristics with a single frequency energy attribute body, but after using multiple frequency division energy attribute RGB modes for mixing, this type of reservoir will show obvious differences from the surrounding rock on the mixed body, which highlights the reservoir instead.

[0088] Step 5: Sand layer interface extraction under high-density isochronal slice control High-density isochronous slices refer to a series of high-density isochronous sequence interpretation horizons extracted by setting the top and bottom windows of the target layer on the basis of the global sequence framework.

[0089] The main marker layer of the Shaximiao Formation is the interlaminar shale, which represents the largest lake flooding surface and can be used as a marker layer with relatively accurate isochronism. Seismic interpretation was completed based on isochronous sequence stratigraphy, and a high-density isochronous sequence stratigraphic model was established. On the basis of the global sequence framework, the top and bottom windows of the target layer were set to make a high-density stratigraphic stack. According to the calibration of the well, after determining the specific position of the stratigraphic layer on the seismic, the slices corresponding to the position of each marker layer in the seismic body under the high-density isochronous model body were extracted to obtain stratigraphic slices of different geological periods. The determined sequence framework was expanded from points to surfaces.

[0090] On high-density isochronous stratigraphic slices, the single-frequency volume and other result data volumes obtained by spectral decomposition using the matching pursuit method (MPD) can be used as input to extract various attribute planes. According to the seismic response characteristics of the "top valley bottom peak" of the channel sand body shown in the channel on the attribute slice plane and the order of appearance of the channel shape, the top and bottom isochronous surfaces of the channel are determined, and the attribute volume of the single-period channel within the time window is extracted, thereby characterizing the lateral distribution and vertical superposition relationship of the river channels of each period.

[0091] The sand layer group sequence thickness control technology based on the high-density sequence stratigraphic model makes up for the limitation of seismic resolution in identifying thin sand layers; the prediction results are quality controlled by making full use of well data, and the isochronous surfaces of the top and bottom of a single-period river channel are determined by multiple wells; the sand bodies are cut vertically by isochronous surfaces, which follows the occurrence of the sequence where the river channel is located and avoids time penetration; at the same time, when the sand body thickness is less than one-eighth of the wavelength and the top and bottom of the sand body cannot be accurately determined by the seismic waveform, the determination of the top and bottom of the sand body based on the combination of well and seismic under the high-density sequence model is also a further supplement to the seismic prediction limit of thin sand layers.

[0092] Conventional technical means are difficult to effectively solve the problems of thick strata, multiple river channel stages, easy penetration of single sand group interpretation, and difficulty in comparing and dividing sand layer groups with wells. This time, targeted amplitude-preserving seismic processing technology was used to change the imaging of the edge of the work area. Based on the global isochronous sequence technology and high-density isochronous sequence slice linkage technology, the Shaximiao Formation in the Qiulin-Shehong-Zhongtaishan area was preliminarily divided into 23 river channel sand groups.

[0093] It is distributed in both the first and second sections of the Shahejie Formation. Five channel stages have been identified in the first section of the Shahejie Formation, four channel stages have been identified in the first section of the Shahejie Formation, six channel stages have been identified in the second section of the Shahejie Formation, five channel stages have been identified in the third section of the Shahejie Formation, and three channel stages have been identified in the fourth section of the Shahejie Formation. The channels within the sandstone group are mainly oriented to the northeast, and several channels with a width of more than 1,000 meters have been developed. On this basis, the channel types are divided according to the impedance relationship between the sand body and the surrounding rock.

[0094] Based on the above understanding of the division of sand layers, the contiguous sand bodies in the region were uniformly numbered. For example, the No. 7 sand layer group is located in the 1st sub-member of the Sha 2, corresponding to the No. 21 sand layer group in Bajiaochang. For example, the No. 8 sand layer group is located in the 1st sub-member of the Sha 2, corresponding to the No. 5 sand layer group in Qiulin, the No. 7 sand layer group in Zhongtaishan, and the No. 6 sand layer group in Jinhua.

[0095] While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the claims.

Claims

1. A high-resolution seismic sequence division method for river channel sand groups, characterized by: The method comprises the following steps, S1, Seismic sequence fine calibration step, obtain drilling data, logging data and seismic data in the study area, and perform synthetic record calibration and seismic sequence fine calibration; S2, well-seismic combined sequence division and comparison steps, using standard wells to divide the well logging sequence, based on the theoretical basis of sequence stratigraphy research, on the basis of synthetic record calibration and identification of various formation interfaces, carry out identification and comparison of seismic reflection layers in the sequence formations of connected wells, determine the seismic reflection characteristics and single well sequence division plan; S3, high-resolution sequence stratigraphic modeling step, performing fault interpretation and stratigraphic interpretation on 3D seismic data, and establishing a high-resolution sequence stratigraphic framework model, i.e., an isochronous stratigraphic model; On the basis of the isochronous stratigraphic model, the target layer is extracted according to the research needs and interpretation results, and the high-density isochronous slices of the target layer are established; S4, high-resolution frequency division sand body identification step under matching pursuit algorithm, select high, medium and low frequencies according to the target layer frequency, use matching pursuit algorithm to obtain high-resolution single-frequency body; perform RGB three-color fusion on the single-frequency body to obtain a set of data bodies sensitive to sand body reflection and frequency division fusion slices based on isochronous stratigraphic model; S5. The step of extracting the interface of the sand layer group under the control of high-density isochronous slices is to comprehensively consider the marker layers with relatively accurate isochronous properties, set the top and bottom windows of the target layer on the basis of the global sequence framework, and make a high-density stratigraphic stack; on the high-density isochronous stratigraphic slices, use the single-frequency body of the matching pursuit method and other data bodies representing the plane distribution of the sand body as input to extract various attribute planes, and determine the top and bottom isochronous surfaces of the channel according to the seismic response characteristics of the channel sand body and the order of appearance of the channel shape shown by the channel on the attribute slice plane, and extract a series of high-density isochronous sequence interpretation horizons to form the stratigraphic interface of the sand layer group.

2. A method for high-resolution seismic sequence division of river channel sand groups according to claim 1, characterized in that: In step S1, when performing synthetic record calibration, acoustic wave synthetic record calibration is adopted, and the acoustic wave synthetic record calibration is performed according to the set principles, wherein the set principles include extracting seismic traces along the trajectory, estimating wavelets from well side traces, giving priority to strong phases, and jointly comparing and calibrating the main survey line and the tie line.

3. A method for high-resolution seismic sequence division of river channel sand groups according to claim 2, characterized in that: When calibrating synthetic records, pay attention to the marker features of the sequence interface and the reflection features of the sand layer group, so that the wave group characteristics of the synthetic seismic record are close to the seismic wave group reflection of the well bypass, ensuring the correct association between the logging data and the seismic data.

4. A method for high-resolution seismic sequence division of a channel sandstone group according to any one of claims 1 to 3, characterized in that: In step S1, the process of evaluating, quality controlling, editing, correcting and reconstructing the well logging curves is carried out before the synthetic log calibration is performed.

5. A method for high-resolution seismic sequence division of river channel sand groups as claimed in claim 4, characterized in that: The correction method of the logging curve includes manual editing, filtering processing or correction processing, wherein the manual editing refers to correcting the abnormal values ​​in the curve point by point, adding a constant value to the amplitude of a certain depth section or the entire well section of the curve, and multiplying the amplitude of a given depth section by the constant value; The filtering process refers to eliminating singular points in the curve by using median filtering and bandpass filtering to achieve the purpose of smoothing the curve; The correction process refers to calculating the error using the seismic logging data and the overall sonic logging data, and then obtaining the error curve, and then correcting the original sonic logging curve with the error curve.

6. A method for high-resolution seismic sequence division of a channel sandstone group according to any one of claims 1 to 3, characterized in that: In step S1, during the fine calibration of the seismic sequence, the frequency of the seismic wavelet is determined by the frequency and bandwidth of the seismic records near the well, and the phase of the seismic wavelet is related to the source and the resolution of the earthquake.

7. A method for high-resolution seismic sequence division of channel sand groups according to claim 6, characterized in that: The dominant frequency of the seismic trace data around the well is analyzed to determine the frequency of the seismic wavelet, and then the zero-phase seismic wavelet is selected. Finally, the dominant frequency and phase of the seismic wavelet are adjusted to achieve the best match between the synthetic record and the seismic trace.

8. A method for high-resolution seismic sequence division of river channel sand groups according to claim 1, characterized in that: In step S2, global model-controlled structural modeling technology is used to interpret the seismic reflection interface, finely interpret faults, and identify and carve sand bodies in the study area.

9. A method for high-resolution seismic sequence division of channel sand groups according to claim 8, characterized in that: In step S2, based on the theoretical foundation of sequence stratigraphy research, on the basis of synthetic record calibration and identification of each formation interface, identification and comparison of seismic reflection layers in connected well sequence strata are carried out to determine the seismic reflection characteristics and the single well sequence division scheme. Specifically, first, a skeleton connected well stratigraphic comparison profile is established based on the standard well sequence division; secondly, the seismic reflection interface that can be continuously compared and traced is determined, and a connected well seismic framework profile is established.

10. A method for high-resolution seismic sequence division of a channel sandstone formation according to any one of claims 1 to 3 or 8 or 9, characterized in that: In step S3, a high-resolution sequence stratigraphic framework model is established. Specifically, based on the interpretation of faults and skeleton profile stratigraphic positions, and based on the cost function of seismic data similarity and geological consistency, a global optimal method is used to spatially deconstruct the seismic data body, and the optimal structure is selected from a large number of possible sequence stratigraphic frameworks. The seismic sequence stratigraphic framework model is established directly from the seismic data for stratigraphic tracing and interpretation.

11. A method for high-resolution seismic sequence division of channel sand groups according to claim 10, characterized in that: First, a model facet grid is established, and the facets formed by the local trace data within the step definition are regarded as the most basic object units; the interconnection of facet points is based on the cost function of seismic data similarity and geological consistency, and the seismic data body is spatially deconstructed based on the global optimal method, and the optimal structure is selected from a large number of possible stratigraphic frameworks. On the basis of considering seismic reflection characteristics, global consistency of stratigraphic deposition, sedimentary thickness, seismic and geological comprehensive factors of stratigraphic inheritance, a global thinking mode is adopted to consider the entire three-dimensional seismic data body as a whole. The interpretation scheme and interpretation mode are based on the seismic and geological information contained in the entire three-dimensional data body, and a relative isochronous framework model is accurately established to automatically complete the stratigraphic tracking interpretation; the same geological age values ​​are connected to obtain an isochronous layer, and countless isochronous layers are stacked to form an isochronous stratigraphic model.

12. A method for high-resolution seismic sequence division of a channel sandstone formation according to any one of claims 1 to 3 or 8 or 9, characterized in that: In step S5, on the high-density isochronous stratigraphic slices, the single-frequency volume and other result data volumes obtained by spectral decomposition using the matching pursuit method are used as input to extract various attribute planes. According to the seismic response characteristics of the "top valley bottom peak" of the channel sand body shown by the channel on the attribute slice plane and the order of appearance of the channel shape, the top and bottom isochronous surfaces of the channel are determined, and the attribute volume of the single-period channel in the time window is extracted, thereby characterizing the lateral distribution and longitudinal superposition relationship of the channels of each period.

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