Frequency division partition identification method for complex stratum

Abstract

The invention discloses a frequency division partition identification method for a complex stratum. The method comprises the steps of S10, stratum distribution prediction; s20, well-to-seismic synthesis record calibration; s30, forward modeling analysis; S40, seismic data frequency division body reconstruction; and S50, performing partition frequency division automatic tracking interpretation: applying different frequency data volumes to realize horizon automatic tracking identification according to a formation distribution prediction result and a well seismic calibration result and a forward modeling analysis result. The method can reduce the recognition error, and can cope with the precise recognition of a complex stratum.

Description

Technical Field

[0001] The invention belongs to the technical field of stratum detection, and in particular relates to a frequency division and partitioning identification method for complex strata. Background Art

[0002] Regarding the stratigraphic contact type of the unconformity, due to the variable lithology of the underlying strata on the unconformity, the diverse lithology combinations above and below the unconformity, and the complex impedance interface, the stratigraphic interface is not obvious in the seismic response, the reflection interface is not clear, and it is difficult to ensure the accuracy of seismic interpretation.

[0003] Taking the Qixia Formation in the GST area as an example, the Liangshan Formation (P1l) and Qixia Formation (P1q) of the Lower Permian in the GST area directly cover the strata of different ages such as the Cambrian (ε), Ordovician (O), and Silurian (S), and from the southeast to the northwest, the strata appear in order from the new to the old distribution characteristics. Under this paleo-geomorphic background, the Permian large-scale transgression was ushered in, and the Liangshan Formation and Qixia Formation sedimentation began. Due to the complex distribution of the underlying strata of the Qixia Formation in the study area and the variable lithology, the interface of the small layer inside Qixia is not obvious in the seismic response, the reflection interface is not clear, and it is difficult to interpret the bottom and the bottom of the bottom in detail. The calibration results show that the calibration position of the bottom varies greatly, which can change from the trough to - / + zero, and some are peaks. The calibration position is controlled by the changes in the underlying contact strata. At present, the seismic interpretation of this area is completely based on the reflection phase axis tracking method of seismic data, so the well-seismic error is ignored. Since the reflection interface is quite different from the actual formation interface, there are obvious errors in the later paleo-geomorphological research, which in turn affects the reliability of the later well location target optimization. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a frequency division and zoning identification method for complex strata, which can reduce the identification error and cope with the accurate identification of complex strata.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a frequency division and partition identification method for complex strata, comprising the steps of:

[0006] S10, Formation distribution prediction: According to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of formations in connected wells, the formations and lithology combination types in different well areas are determined to obtain the formation distribution prediction results;

[0007] S20, calibration of well-seismic synthetic records: according to the formation distribution prediction results, the impedance interface is determined for different formations and lithology contact relationships; according to different impedance interfaces, the variable wavelet synthetic record calibration is carried out for each well to determine the different formation contact relationships and their corresponding lithology combinations and impedance interface conditions. The sensitive frequency and corresponding seismic reflection characteristics are determined to obtain the well-seismic calibration results;

[0008] S30, forward analysis: According to the formation distribution prediction results and well-seismic calibration results, the formation and lithology contact geological model is established. According to different lithology velocity and density parameters, the contact relationship of different formations and their corresponding lithology combinations and the sensitive frequency and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling to obtain the forward analysis results;

[0009] S40, reconstruction of seismic data frequency division volume: including spectrum decomposition to form multiple frequency division volumes by performing wavelet frequency division on seismic data, and frequency division reconstruction to form seismic data with bandwidth and main frequency by performing feature reconstruction analysis on multiple frequency division volumes, thereby obtaining data volumes with different frequencies;

[0010] S50, automatic tracking and interpretation of different frequencies: Based on the predicted results of stratum distribution, according to the well-seismic calibration results and forward analysis results, different frequency data bodies are applied to realize automatic tracking and identification of strata.

[0011] Furthermore, according to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of the formations of connected wells, the formations and lithology combination types of different well areas are determined, including the following steps:

[0012] Based on the identified wells, the strata are divided into different sequence units according to the sedimentary characteristics and geological records, and the identification marks of the interfaces of different strata are clearly defined;

[0013] Single well sequence division: Based on the lithologic combination, stratigraphic marks, core observation and logging interpretation analysis of the formation, starting from the downhole data, through several factors such as electrical properties, lithology and lithofacies changes, and based on the sequence stratigraphic analysis of the natural gamma curve and resistivity curve in the single well logging curve, the sequence stratigraphic division scheme is established to clarify the characteristics of the formation and lithologic changes and the reservoir development interval;

[0014] Well-connected stratigraphic comparison: Based on the single-well sequence division, the characteristics of the sequence interface curves of all wells are sorted out, and the comparability of the natural gamma curves and resistivity curves of the sequence interface in the entire area are summarized. Based on this, a sequence stratigraphic framework is established to determine the lateral comparison characteristics of each stratum. At the same time, according to the results of the sequence well-connected comparison analysis, adjustments are made to the wells with unreasonable single-well sequence divisions.

[0015] Furthermore, according to the formation distribution prediction result, the impedance interface is determined for different formations and lithology contact relationships, including the following steps:

[0016] Analysis of lithologic contact relationship of sequence interface: Based on the results of single well sequence division and well-connected sequence comparison, the lithologic characteristics of the overlying and underlying strata of the Permian stratigraphic interface of different wells are sorted out to obtain the lithologic contact relationship type of the Permian stratigraphic interface in the identified area, as well as the plane distribution range of single wells with different lithologic combination types;

[0017] Sequence interface impedance analysis: Based on the analysis of lithology differences at sequence interfaces in different well areas, the impedance values ​​of different lithologies are statistically analyzed according to logging data, so as to further classify the sequence interfaces from the perspective of impedance changes.

[0018] Furthermore, according to different impedance interfaces, variable sub-wave synthesis record calibration is carried out for each well to determine the sensitive frequency and corresponding seismic reflection characteristics under different stratum contact relationships and corresponding lithology combinations and impedance interface conditions, including the following steps:

[0019] According to the results of lithology and impedance classification of sequence interface, calibration of well-seismic synthetic records was carried out in different zones and frequencies to clarify the sensitive frequencies and corresponding seismic reflection characteristics under the impedance interface conditions corresponding to different lithology combinations.

[0020] Furthermore, according to the formation distribution prediction results and the well-seismic calibration results, a formation and lithology contact geological model is established, including the following steps:

[0021] Based on the stratigraphic contact types revealed by all wells in the study area, including lithology, thickness, contact relationship, P-wave velocity, S-wave velocity and density, a geological model was established based on actual drilling.

[0022] Furthermore, according to different lithology velocities and density parameters, different stratum contact relationships and their corresponding lithology combinations and sensitive frequencies and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling, including the steps of: establishing a geological model based on actual drilling, and according to the sensitive frequency analysis results of different lithology contact types and their corresponding impedance interfaces, using the frequency to carry out forward analysis on the corresponding geological model, so as to further clarify the seismic reflection characteristics of the stratum interface under different model conditions.

[0023] Furthermore, the spectrum decomposition includes the steps of: converting the seismic data from the time domain to the frequency domain by wavelet transform, decomposing the seismic data into tuned bodies of different frequency domains, the amplitude spectrum generated after the conversion can identify the temporal thickness change of the stratum, and the phase spectrum can detect the geological discontinuity in the lateral direction of the geological body; using the slices of the tuned frequency amplitude data body to determine the temporal and spatial distribution of the abnormal body; using the slices of the tuned frequency instantaneous phase data body to determine the boundary of the abnormal body;

[0024] Frequency reconstruction analyzes seismic data, selects frequency data bodies that can reflect different geological targets, and then reconstructs the frequency data bodies in the frequency domain to ultimately form seismic data with bandwidth and main frequency.

[0025] Furthermore, the automatic tracking and interpretation of the zone and frequency division: according to the prediction results of the formation distribution, according to the well seismic calibration results and the forward analysis results, different frequency data bodies are applied to realize the automatic tracking and identification of the layer, including the following steps:

[0026] Comprehensively determine the sensitive frequencies corresponding to different lithology combinations and their impedance interfaces as well as the seismic reflection characteristics of the formation interface, optimize the frequency division reconstruction data, calibrate and determine the formation tracking plan;

[0027] According to the well areas with different lithology combinations and impedance interface distribution, the corresponding sensitive frequency division reconstruction data is selected to carry out seed point interpretation;

[0028] Based on the seed points, the automatic tracking algorithm is applied to track the interfaces of each stratum with the distribution range of the stratum as the boundary;

[0029] Stratum stitching: for the interpretation results of different well areas and different data bodies, according to the distribution range of the strata, the interpretation results of each stratum interface are stitched together to form the interpretation results of the entire area.

[0030] The beneficial effects of adopting this technical solution are:

[0031] The present invention proposes a frequency-division and zoning interpretation scheme for complex strata, complex lithologies, and complex impedance contact stratum interfaces, which effectively improves the accuracy of stratum interpretation, thereby further improving the accuracy of later paleogeomorphology characterization and reservoir prediction results, effectively improving the success rate of well deployment, and reducing production costs.

[0032] The present invention is based on the causal method. Well data analysis clarifies the reasons for the complexity of the seismic reflection characteristics of the formation. Based on this, comprehensive calibration and forward modeling clarify the stable and traceable seismic response characteristics of the formation interface. Automatic tracking technology is used to effectively reduce the uncertainty of the interpretation results caused by human intervention, and the interpretation results are more objective. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic flow chart of a frequency division and partition identification method for complex strata according to the present invention;

[0034] Figure 2 Schematic diagram of the sequence stratigraphic division of Well X in an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of sequence stratigraphic division of Well Y in an embodiment of the present invention;

[0036] Figure 4 Schematic diagram of parameters and formation structure types of Model 1 in an embodiment of the present invention;

[0037] Figure 5 Schematic diagram of parameters and formation structure types of Model 2 in an embodiment of the present invention;

[0038] Figure 6 Schematic diagram of parameters and formation structure types of Model 3 in an embodiment of the present invention;

[0039] Figure 7A schematic diagram of the process flow of frequency division and reconstruction in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below with reference to the accompanying drawings.

[0041] In this embodiment, see Figure 1 As shown, the present invention proposes a frequency division and partition identification method for complex formations, comprising the steps of:

[0042] S10, Formation distribution prediction: According to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of formations in connected wells, the formations and lithology combination types in different well areas are determined to obtain the formation distribution prediction results;

[0043] S20, calibration of well-seismic synthetic records: according to the formation distribution prediction results, the impedance interface is determined for different formations and lithology contact relationships; according to different impedance interfaces, the variable wavelet synthetic record calibration is carried out for each well to determine the different formation contact relationships and their corresponding lithology combinations and impedance interface conditions. The sensitive frequency and corresponding seismic reflection characteristics are determined to obtain the well-seismic calibration results;

[0044] S30, forward analysis: According to the formation distribution prediction results and well-seismic calibration results, the formation and lithology contact geological model is established. According to different lithology velocity and density parameters, the contact relationship of different formations and their corresponding lithology combinations and the sensitive frequency and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling to obtain the forward analysis results;

[0045] S40, reconstruction of seismic data frequency division volume: including spectrum decomposition to form multiple frequency division volumes by performing wavelet frequency division on seismic data, and frequency division reconstruction to form seismic data with bandwidth and main frequency by performing feature reconstruction analysis on multiple frequency division volumes, thereby obtaining data volumes with different frequencies;

[0046] S50, automatic tracking and interpretation of different frequencies: Based on the predicted results of stratum distribution, according to the well-seismic calibration results and forward analysis results, different frequency data bodies are applied to realize automatic tracking and identification of strata.

[0047] As an optimization scheme of the above embodiment, according to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of the formations of connected wells, the formations and lithology combination types of different well areas are determined, including the following steps:

[0048] Based on the confirmed drilled wells, sedimentary characteristics and geological records, the strata are divided into different stratigraphic units, and the identification marks of the interfaces of different strata are clearly defined.

[0049] Take the Lower Permian in the GST region as an example:

[0050] The top and bottom interfaces of the Lower Permian Liangshan Formation (P1l) are based on the regional weathering crust caused by the Yunnan Movement. As the seawater invaded from the northwest and southeast directions of the basin, the Liangshan Formation strata, which are mainly composed of coal-bearing clastic rock deposits, were formed. Within the working area, they are covered by the Lower Silurian Longmaxi Formation (S1l), the Middle Ordovician Pagoda Formation (Q2b), the Shizipu Formation (Q2s), the Lower Ordovician Meitan Formation (Q1m), the Honghuayuan Formation (Q1h) and the Tongzi Formation (Q1t), or older Cambrian (∈) strata, and are the product of the conversion from land to sea in the early stage of the transgression.

[0051] The angular unconformity between the Liangshan Formation of the Lower Permian and the underlying strata is a typical I-order sequence interface. This interface is a stratigraphic diachronous surface, covering multiple strata including the Silurian, Ordovician, and Cambrian. As the sea level rises, the scope of seawater inundation expands, and the sedimentary environment changes to the vast carbonate platform deposits of the Qixia Formation. The clastic sedimentary mudstone limestone and gray shale of the Liangshan Formation gradually transition upward to the platform carbonate deposits of the Qixia Formation, which is the product of continuous marine transgression. Therefore, the interface between the Liangshan Formation and the Qixia Formation is not a III-order sequence interface.

[0052] The interface between the interior of the Lower Permian Qixia Formation and the first member of the Maokou Formation:

[0053] The key to dividing and comparing sequence stratigraphy in the Lower Permian Qixia Formation is to accurately identify the lithology-lithofacies transition surface in strata where the unconformity surface is not developed or difficult to identify. Comprehensive comparison of multiple types of logging curves shows that the use of logging response sequences based on natural gamma (GR) curves, resistivity (RT) curves and wash zone resistivity (RXO) curves can accurately divide and compare the sequence stratigraphy inside the Qixia Formation in the work area. The Qixia Formation transforms from the bottom of the mud-rich micrite and granular limestone to the upper dolomite and granular limestone, forming a lithology-lithofacies transition surface inside the Qixia Formation. This transition surface is marked by the appearance of dolomite in most wells. Between the Qixia Formation and the Maokou Formation is the second lithology-lithofacies transition surface, which is manifested as the light gray granular limestone of the Qixia Formation to the regionally developed "oolites" limestone with a high mud content in the first section of the Maokou Formation, and the two are in parallel unconformable contact.

[0054] Single well sequence division: Using the lithological combination of the strata, stratigraphic marks, core observations and logging interpretation and analysis, starting from the downhole data, through several factors such as electrical properties, lithology and lithofacies changes, based on the sequence stratigraphic analysis of the natural gamma curve and resistivity curve in the single well logging curve, a sequence stratigraphic division scheme is established to clarify the characteristics of the strata, lithological changes and reservoir development intervals.

[0055] Take Well X and Well Y as an example ( Figure 2 , Figure 3), the GR of the first section of the Liangshan Formation + the Qixia Formation shows a continuous decreasing trend, and the RT / RXO curve is bell-shaped; the GR curve of the second section of the Qixia Formation changes to a smooth tooth-like low value, and the RT / RXO curve shows a finger-like high value. The overall electrical characteristics show that the GR curve decreases from the first section to the second section of the Qixia Formation; the lithology of the high GR and low resistivity section at the bottom is dark gray mud-crystal limestone, which is a deep-water low-energy sedimentary environment. Petrological signs: The lithology of each cycle gradually changes from mud-crystal bioclastic limestone to bright crystal granular limestone from bottom to top, and the lithology changes at the cycle interface are clear. Logging signs: The GR of each cycle shows a box-like feature of relatively high values ​​changing from fingers to low values, and the resistivity gradually decreases from bottom to top. Geochemical signs: Both carbon isotopes and trace elements near the interface have mutation characteristics.

[0056] Well-connected stratigraphic comparison: Based on the single-well sequence division, the characteristics of the sequence interface curves of all wells are sorted out, and the comparability of the natural gamma curves and resistivity curves of the sequence interface in the entire area are summarized. Based on this, a sequence stratigraphic framework is established to determine the lateral comparison characteristics of each stratum. At the same time, according to the results of the sequence well-connected comparison analysis, adjustments are made to the wells with unreasonable single-well sequence divisions.

[0057] As an optimization scheme of the above embodiment, according to the formation distribution prediction result, the impedance interface is determined for different formations and lithology contact relationships, including the following steps:

[0058] Analysis of lithologic contact relationship of sequence interface: Based on the results of single well sequence division and well-connected sequence comparison, the lithologic characteristics of the overlying and underlying strata of the Permian stratigraphic interface of different wells are sorted out to obtain the lithologic contact relationship type of the Permian stratigraphic interface in the identified area, as well as the plane distribution range of single wells with different lithologic combination types;

[0059] Taking the GST area as an example, the types are divided into five categories according to the different underlying contact strata of the Permian, namely, contact Longmaxi Formation mudstone, Pagoda Formation-Shizipu Formation limestone, Meitan Formation mudstone, limestone contact, Tongzi Formation-Honghuayuan Formation limestone and Cambrian dolomite.

[0060] Sequence interface impedance analysis: Based on the analysis of lithology differences at sequence interfaces in different well areas, the impedance values ​​of different lithologies are statistically analyzed according to logging data, so as to further classify the sequence interfaces from the perspective of impedance changes.

[0061] According to the impedance relationship of different lithological interfaces, they are combined into two categories: the first category is that the Qixia Formation limestone contacts the Liangshan Formation thin mudstone and the Silurian mudstone, and the impedance interface is high impedance contact and low impedance, and the impedance difference is large; the second category is that the Qixia Formation limestone contacts the Liangshan Formation thin mudstone and the Ordovician Meitan Formation limestone, showing the characteristics of high impedance contact and medium-low impedance, and the impedance interface is relatively large; the third category is that the Qixia Formation limestone contacts the Ordovician or Cambrian thick limestone, showing high impedance contact and high impedance, and the impedance difference is small.

[0062] As an optimization scheme of the above embodiment, according to different impedance interfaces, variable sub-wave synthesis record calibration is carried out for each well to determine the sensitive frequency and corresponding seismic reflection characteristics under different stratum contact relationships and corresponding lithology combinations and impedance interface conditions, including the following steps:

[0063] According to the results of lithology and impedance classification of sequence interface, calibration of well-seismic synthetic records was carried out in different zones and frequencies to clarify the sensitive frequencies and corresponding seismic reflection characteristics under the impedance interface conditions corresponding to different lithology combinations.

[0064] (1) High impedance / low impedance interface characteristics analysis:

[0065] Taking the underlying contact stratum of the Permian as the Silurian Longmaxi Formation mudstone as an example, a total of 8 wells of this type were drilled. For each well, the acoustic wave curve and density curve were used to make synthetic records. The main frequency of the synthetic record wavelet was the Ricker wavelet type, which gradually changed from 20Hz to 45Hz. The characteristics of the stratum interface under different frequency conditions were analyzed and summarized, so as to select the most sensitive frequency. Under this frequency condition, the bottom and bottom interfaces are the most stable and traceable. The analysis results show that the sensitive frequency of the bottom is 45Hz, with trough reflection; the sensitive frequency of the bottom is 45Hz, which is manifested as zero phase reflection under the peak.

[0066] (2) High impedance / medium and low impedance interface characteristics analysis:

[0067] For the underlying contact strata of the Permian System, which are mudstone or marlstone of the Meitan Formation, a total of 35 wells of this type have been drilled. For these 35 wells, the calibration and comparison of variable wavelet synthesis records were carried out based on the acoustic curve and density curve, and the most sensitive frequencies of the bottom and the second bottom of the ...

[0068] (3) High impedance / high impedance interface characteristics analysis:

[0069] When the underlying contact strata of the Permian are limestones of the Pagoda Formation, the Shizipu Formation, the Tongzi Formation, and the Honghuayuan Formation or Cambrian dolomite, the impedance interface type is a high impedance and high impedance docking mode. The same method was used to calibrate the variable wavelet synthetic records for 36 wells of this type; the results showed that when the main frequency of the seismic wavelet was 15Hz-20Hz, the bottom of Qixia showed zero phase on the wave crest, and as the main frequency of the seismic wavelet increased, the bottom of Qixia gradually shifted to the trough; when the main frequency of the seismic wavelet was 40Hz-55Hz, the bottom of the second section of Qixia showed zero phase below the wave crest and was relatively stable. This shows that when the underlying contact strata of the Permian is limestone and the impedance interface is high impedance / high impedance, the sensitive frequency of the bottom of Qixia is 20Hz, while the sensitive frequency of the bottom of Qixia II is 40Hz-45Hz.

[0070] As an optimization scheme of the above embodiment, a formation and lithology contact geological model is established according to the formation distribution prediction results and the well-seismic calibration results, including the following steps:

[0071] Based on the stratigraphic contact types revealed by all wells in the study area, including lithology, thickness, contact relationship, P-wave velocity, S-wave velocity and density, a geological model was established based on actual drilling.

[0072] Taking the GST region as an example, the following three geological models are recommended:

[0073] Model 1: The underlying strata are in contact with P1l thin mudstone and S1l mudstone or directly in contact with S1l mudstone. The strata of Maoer, Maosan, Maoyi, Qier and Qiyi are all in conformable contact. Qiyi and Liangshan Formation, Qiyi and Longmaxi, Liangshan and Longmaxi are all in unconformable contact. The relevant thickness, velocity and density parameters are shown in Figure 4 .

[0074] Model 2: The underlying strata are in contact with the thin P1l mudstone and the O1m marlstone or directly in contact with the O1m mudstone. The contact mode and related velocity and density parameters are shown in Figure 5 .

[0075] Model 3: The underlying strata contact the P1l thin mudstone and O1t / O1h / O3b / O2s limestone and Cambrian dolomite. The contact mode and related velocity and density parameters are shown in Figure 6 .

[0076] As an optimization scheme for the above-mentioned embodiment, according to different lithology velocities and density parameters, different stratum contact relationships and their corresponding lithology combinations and sensitive frequencies and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling, including the steps of: establishing a geological model based on actual drilling, and according to the sensitive frequency analysis results of different lithology contact types and their corresponding impedance interfaces, using the frequency to carry out forward analysis on the corresponding geological model, so as to further clarify the seismic reflection characteristics of the stratum interface under different model conditions.

[0077] The stratigraphic forward model based on the above two categories and five subcategories once again shows that when the underlying stratum is a high-impedance limestone area, the bottom can be better identified when the main seismic frequency is 20Hz, showing zero phase above the wave crest; the second bottom can be better identified in the 45Hz seismic data, showing zero phase below the wave crest. When the underlying stratum is a low-impedance mudstone area, the bottom and second bottom can be better identified when the main seismic frequency is 45Hz, showing trough reflection and zero phase reflection below the wave crest, respectively.

[0078] As an optimization solution of the above embodiment, Figure 7As shown, the spectrum decomposition includes the following steps: converting seismic data from the time domain to the frequency domain by wavelet transform, decomposing the seismic data into tuned bodies of different frequency domains, the amplitude spectrum generated after the conversion can identify the temporal thickness change of the stratum, and the phase spectrum can detect the geological discontinuity in the lateral direction of the geological body; using the slices of the tuned frequency amplitude data body to determine the temporal and spatial distribution of the abnormal body; using the slices of the tuned frequency instantaneous phase data body to determine the boundary of the abnormal body;

[0079] Frequency reconstruction analyzes seismic data, selects frequency data bodies that can reflect different geological targets, and then reconstructs the frequency data bodies in the frequency domain to ultimately form seismic data with bandwidth and main frequency.

[0080] As an optimization scheme of the above embodiment, automatic tracking and interpretation of zone-by-zone frequency division: for the formation distribution prediction results, according to the well seismic calibration results and the forward analysis results, different frequency data bodies are applied to realize automatic layer tracking and identification, including the following steps:

[0081] Comprehensively determine the sensitive frequencies corresponding to different lithology combinations and their impedance interfaces as well as the seismic reflection characteristics of the formation interface, optimize the frequency division reconstruction data, calibrate and determine the formation tracking plan;

[0082] According to the well areas with different lithology combinations and impedance interface distribution, the corresponding sensitive frequency division reconstruction data is selected to carry out seed point interpretation;

[0083] Based on the seed points, the automatic tracking algorithm is applied to track the interfaces of each stratum with the distribution range of the stratum as the boundary;

[0084] Stratum stitching: for the interpretation results of different well areas and different data bodies, according to the distribution range of the strata, the interpretation results of each stratum interface are stitched together to form the interpretation results of the entire area.

[0085] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A frequency division and partition identification method for complex strata, characterized in that: Includes steps: S10, Formation distribution prediction: According to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of formations in connected wells, the formations and lithology combination types in different well areas are determined to obtain the formation distribution prediction results; S20, calibration of well-seismic synthetic records: according to the formation distribution prediction results, the impedance interface is determined for different formations and lithology contact relationships; according to different impedance interfaces, the variable wavelet synthetic record calibration is carried out for each well to determine the different formation contact relationships and their corresponding lithology combinations and impedance interface conditions. The sensitive frequency and corresponding seismic reflection characteristics are determined to obtain the well-seismic calibration results; S30, forward analysis: According to the formation distribution prediction results and well-seismic calibration results, the formation and lithology contact geological model is established. According to different lithology velocity and density parameters, the contact relationship of different formations and their corresponding lithology combinations and the sensitive frequency and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling to obtain the forward analysis results; S40, reconstruction of seismic data frequency division volume: including spectrum decomposition to form multiple frequency division volumes by performing wavelet frequency division on seismic data, and frequency division reconstruction to form seismic data with bandwidth and main frequency by performing feature reconstruction analysis on multiple frequency division volumes, thereby obtaining data volumes with different frequencies; S50, automatic tracking and interpretation of different frequencies: Based on the predicted results of stratum distribution, according to the well-seismic calibration results and forward analysis results, different frequency data bodies are applied to realize automatic tracking and identification of strata.

2. A frequency division and partition identification method for complex strata according to claim 1, characterized in that: According to the wells that have been drilled, the sequence division of single wells and the comparative interpretation of the formations of connected wells, the formations and lithology combination types of different well areas are determined, including the following steps: Based on the identified wells, the strata are divided into different sequence units according to the sedimentary characteristics and geological records, and the identification marks of the interfaces of different strata are clearly defined; Single well sequence division: Based on the lithologic combination, stratigraphic marks, core observation and logging interpretation analysis of the formation, starting from the downhole data, through several factors such as electrical properties, lithology and lithofacies changes, and based on the sequence stratigraphic analysis of the natural gamma curve and resistivity curve in the single well logging curve, the sequence stratigraphic division scheme is established to clarify the characteristics of the formation and lithologic changes and the reservoir development interval; Well-connected stratigraphic comparison: Based on the single-well sequence division, the characteristics of the sequence interface curves of all wells are sorted out, and the comparability of the natural gamma curves and resistivity curves of the sequence interface in the entire area are summarized. Based on this, a sequence stratigraphic framework is established to determine the lateral comparison characteristics of each stratum. At the same time, according to the results of the sequence well-connected comparison analysis, adjustments are made to the wells with unreasonable single-well sequence divisions.

3. A frequency division and partition identification method for complex strata according to claim 2, characterized in that: According to the formation distribution prediction results, the impedance interface is determined for different formations and lithology contact relationships, including the following steps: Analysis of lithologic contact relationship of sequence interface: Based on the results of single well sequence division and well-connected sequence comparison, the lithologic characteristics of the overlying and underlying strata of the Permian stratigraphic interface of different wells are sorted out to obtain the lithologic contact relationship type of the Permian stratigraphic interface in the identified area, as well as the plane distribution range of single wells with different lithologic combination types; Sequence interface impedance analysis: Based on the analysis of lithology differences at sequence interfaces in different well areas, the impedance values ​​of different lithologies are statistically analyzed according to logging data, so as to further classify the sequence interfaces from the perspective of impedance changes.

4. A frequency division and partition identification method for complex strata according to claim 3, characterized in that: According to different impedance interfaces, variable sub-wave synthesis record calibration is carried out for each well to determine the contact relationship of different formations and their corresponding lithology combinations and sensitive frequencies and corresponding seismic reflection characteristics under impedance interface conditions, including the following steps: According to the results of lithology and impedance classification of sequence interface, calibration of well-seismic synthetic records was carried out in different zones and frequencies to clarify the sensitive frequencies and corresponding seismic reflection characteristics under the impedance interface conditions corresponding to different lithology combinations.

5. A frequency division and partition identification method for complex strata according to claim 4, characterized in that: According to the formation distribution prediction results and well-seismic calibration results, the formation and lithology contact geological model is established, including the following steps: Based on the stratigraphic contact types revealed by all wells in the study area, including lithology, thickness, contact relationship, P-wave velocity, S-wave velocity and density, a geological model was established based on actual drilling.

6. A frequency division and partition identification method for complex strata according to claim 5, characterized in that: According to different lithology velocity and density parameters, different stratum contact relationships and their corresponding lithology combinations and sensitive frequencies and corresponding seismic reflection characteristics under impedance interface conditions are further confirmed through forward modeling, including the following steps: establishing a geological model based on actual drilling, and according to the sensitive frequency analysis results of different lithology contact types and their corresponding impedance interfaces, using the frequency to carry out forward analysis for the corresponding geological model, so as to further clarify the seismic reflection characteristics of the stratum interface under different model conditions.

7. A frequency division and partition identification method for complex strata according to claim 1, characterized in that: The spectrum decomposition includes the following steps: converting seismic data from the time domain to the frequency domain through wavelet transform, decomposing the seismic data into tuned bodies of different frequency domains, the amplitude spectrum generated after the conversion can identify the temporal thickness change of the stratum, and the phase spectrum can detect the geological discontinuity in the lateral direction of the geological body; using the slices of the tuned frequency amplitude data body to determine the temporal and spatial distribution of the abnormal body; using the slices of the tuned frequency instantaneous phase data body to determine the boundary of the abnormal body; Frequency reconstruction analyzes seismic data to select frequency data volumes that can reflect different geological targets, and then reconstructs the frequency data volumes in the frequency domain to ultimately form seismic data with bandwidth and main frequency.

8. The frequency division and partition identification method for complex strata according to claim 1 is characterized in that: Automatic tracking and interpretation of zoning and frequency division: Based on the predicted results of stratum distribution, according to the well-seismic calibration results and forward analysis results, different frequency data bodies are applied to realize automatic stratum tracking and identification, including the following steps: Comprehensively determine the sensitive frequencies corresponding to different lithology combinations and their impedance interfaces as well as the seismic reflection characteristics of the formation interface, optimize the frequency division reconstruction data, calibrate and determine the formation tracking plan; According to the well areas with different lithology combinations and impedance interface distribution, the corresponding sensitive frequency division reconstruction data is selected to carry out seed point interpretation; Based on the seed points, the automatic tracking algorithm is applied to track the interfaces of each stratum with the distribution range of the stratum as the boundary; Stratum stitching: for the interpretation results of different well areas and different data bodies, according to the distribution range of the strata, the interpretation results of each stratum interface are stitched together to form the interpretation results of the entire area.

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