A method for finely depicting a shallow discontinuous channel based on seismic attributes

Abstract

The application discloses a method for finely depicting a shallow discontinuous channel based on seismic attributes, and relates to the technical field of oil and natural gas exploration and development. The method is based on amplitude attribute means and combined with a seismic section technology to open a time window in the time domain or the depth domain of a research object. On the basis of seismic horizon interpretation, the method controls two horizons of top and bottom surfaces, splits in the vertical direction along the horizon direction, splits a certain number of sections according to a certain proportion between the two horizons, and sequentially superimposes channel features recognized by amplitude attributes on a single section on a plane graph in sequence. Thus, the method achieves the technical method for identifying a delta front underwater channel with a mud-sand interbedding and mud-bundled sandstone combination in a shallow layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploration and development, more particularly to a method for fine description of shallow discontinuous channel based on seismic attributes. BACKGROUND

[0002] The application of seismic attribute technology runs through all aspects of seismic interpretation (including structural interpretation, lithological interpretation and oil and gas reservoir interpretation). In the mid-1990s, various geostatistical methods were widely used in attribute extraction, such as covariance, linear regression, wavelet transform, simulated annealing method, etc. At present, amplitude, spectral decomposition, waveform clustering and other seismic attribute technologies play an important role in identifying and qualitatively describing faults, channel sand bodies, etc. In view of the characteristics of channel sand bodies, a set of patterns for sedimentary facies analysis, reservoir prediction and lithological interpretation by comprehensively using multiple attributes is explored, taking single well facies analysis to obtain sedimentary patterns as a guide and taking fine synthetic seismic record calibration as a bridge, and good geological results have been achieved.

[0003] In the aspect of geophysical reservoir prediction technology, early technologies such as amplitude, frequency, phase, correlation, waveform clustering and three-dimensional visualization were mainly used for channel reservoir prediction and description, and obvious results were achieved in the areas with positive structural belts, large reservoir thickness and relatively easy-to-identify geophysical characteristics. With the expansion of exploration and development areas, the increasing complexity of predicted geological features and the demand for fine and quantitative geophysical prediction in development (such as the need to clearly understand the distribution of each single channel, the internal sedimentary structure of the channel, the thickness of thin reservoirs, and the heterogeneity of reservoir properties), the limitations of early technologies are becoming more and more obvious, and the prediction accuracy is difficult to meet the production needs.

[0004] In recent years, the integrated research idea of geology and geophysics has been established, and important progress has been made in geophysical prediction technology through scientific and technological research. Key methods and technologies such as channel sedimentary sequence identification, reservoir superimposed pattern identification, phase fine description and quantitative description have been successfully applied.

[0005] With the continuous development of geophysical technology, the current commonly used technologies for describing continuous thick channel high-quality sand bodies mainly include seismic inversion, seismic attribute analysis and seismic frequency division. These technologies have obvious effects in predicting thick channel sand bodies with good continuity (identification of multiple channels in the Shaximiao Formation of the Sichuan Basin) whose thickness meets the requirements of current seismic resolution. However, in the thick delta front underwater distributary channel sandstone to the Bin shallow lacustrine facies represented by the Xujiahe Formation in the Sichuan Basin, due to the frequent superimposition and diversion of the channel, the boundary of the underwater distributary channel is not clear, and the lithological combination is mainly complex combination of dark mudstone interbedded with thin layer of argillaceous siltstone and siltstone, mud-pack sand and sand-mud interbedding. It is difficult to clearly describe the underwater distributary channel of the delta front in the study area from such mud-sand interbedding and mud-pack sandstone lithological combination using conventional seismic technology. SUMMARY

[0006] In order to overcome the defects and deficiencies existing in the prior art, the present application provides a method for finely depicting a shallow discontinuous channel based on seismic attributes. On the basis of comprehensively using multiple sets of existing channel depicting technologies, combining the understanding of the response of the entire channel in the earthquake by the artificial, fusing the seismic slice technology, and with the help of commercial software, the channel boundary which cannot be clearly depicted by the conventional technology with poor continuity is identified. With the increasing difficulty of oil and gas exploration, how to identify and depict the discontinuous channel under the background of complex lithological combination is urgently needed to be solved by the present application. The present application is not obvious in depicting the channel characteristics by simply using the commonly used forward simulation technology, reflection feature analysis, seismic inversion technology, seismic attribute analysis technology and seismic frequency division technology. The method provided by the present application is simple and efficient, the channel characteristics are clear, and the discontinuous channel under the background of mud sand or thin mud sand interbedded deposition is more effective from the prediction result. The biggest difference between the present application and the existing technology is that the present application is based on the existing technology, and the entire target area channel is superimposed in the stratigraphic order with the help of commercial software and accurate stratigraphic slice, which to a great extent solves the identification of discontinuous channel under the background of complex lithological combination.

[0007] In order to solve the problems existing in the prior art, the present application is realized by the following technical scheme.

[0008] The present application provides a method for finely depicting a shallow discontinuous channel based on seismic attributes, which comprises the following steps:

[0009] S1, carrying out well-seismic fine calibration of channel sand body and studying the seismic response of channel sand body;

[0010] S2, selecting a root mean square amplitude attribute to predict the planar distribution of channel sand body;

[0011] S3, observing the characteristics of the root mean square amplitude attribute on a single slice by using the stratigraphic slice technology, and analyzing and screening along the slice according to the attribute information;

[0012] S4, superimposing the screened slices according to the original order of the slices;

[0013] S5, obtaining the planar distribution characteristics of the channel boundary of the entire research area on the same plane, and further predicting and analyzing the sediment source and the favorable reservoir distribution area.

[0014] Further preferably, in the step S2, the selection of the root mean square amplitude attribute to predict the planar distribution of channel sand body is specifically that, on the basis of the horizon interpretation, the top and bottom horizons of the target layer are controlled, the root mean square amplitude attribute is extracted along the layers, and the shallow channel is identified by using the root mean square amplitude attribute.

[0015] Further preferably, in the step S3, based on the extracted root mean square amplitude attribute, the top and bottom horizons of the target layer of the study area are selected, and a plurality of thin layers are interpolated along the two relatively stable horizons according to the idea of average division; the planar distribution characteristics are analyzed through the attribute information displayed by the plurality of slices of the three-dimensional seismic data.

[0016] Further preferably, in the step S3, based on the extracted root mean square amplitude attribute, the top and bottom horizons of the target layer of the study area are selected, and a plurality of thin layers are interpolated along the two relatively stable horizons according to the idea of average division; the planar distribution characteristics are analyzed through the attribute information displayed by the plurality of slices of the three-dimensional seismic data.

[0017] Further preferably, the number of stratigraphic slices of the entire target layer is set according to the time requirement of the target layer.

[0018] Further preferably, in the step S3, the analysis and screening are specifically that the attribute characteristics on each slice are browsed and analyzed, and the slice in which the local river channel boundary characteristic information is clear is screened out.

[0019] Further preferably, in the step S4, the stratigraphic slices of the target layer screened out are superimposed in the original division order by using the commercial software, and the root mean square amplitude attributes extracted from the stratigraphic slices of the entire target layer are displayed on the same plan.

[0020] Further preferably, in the step S4, the amplitude variation characteristics on the stratigraphic slices of the entire target layer are superimposed.

[0021] Further preferably, in the step S4, the commercial software is Petrel software.

[0022] Further preferably, in the step S1, the three-dimensional seismic data with good imaging, high main frequency and wide frequency band range in the study area are selected for horizon fine interpretation.

[0023] Compared with the prior art, the beneficial technical effects brought by the present application are as follows:

[0024] 1. The present application combines the amplitude attribute means with the seismic slicing technology to open a time window in the time domain or the depth domain of the research object on the basis of the amplitude attribute means. On the basis of the seismic horizon interpretation, the top surface and the bottom surface are controlled, the slicing is carried out in the longitudinal direction along the horizon, the horizon between the two horizons is divided into a certain number of slices according to a certain ratio, and the channel features identified by the amplitude attribute on the single slice are sequentially superimposed on a plane graph according to the order of the slices. Thus, the technical method for identifying the shallow delta front underwater channel with the mud-sand interbedding and the mud-bundled sand lithologic combination is achieved.

[0025] 2. The shallow channel appears as obvious bright point reflection features on the 3D seismic profile. If the conventional channel identification technology is used to describe along a certain time window, it is difficult to clearly describe the channel contour on the isochronous surface due to the influence of the complex lithologic combination of the sand-mud interbedding and the mud-bundled sand. The root mean square amplitude attribute is obtained by the constant vertical length (time interval) between the layers or the area defined by the two horizons. The root mean square amplitude attribute is very effective for identifying the shallow channel with the local sand-mud interbedding bright point reflection.

[0026] 3. Compared with the existing technology, the present application integrates various seismic prediction methods, uses the fusion seismic slicing technology, and uses the commercial software to identify the hidden channel boundary which cannot be clearly described by the conventional technology. The present application has the characteristics of high accuracy, simple method, easy operation, and strong comprehensiveness, and has advancement.

[0027] 4. The present application fuses the stratum slicing technology. On the one hand, the overall appearance of the sedimentary body is observed, and the development characteristics of the sedimentary body are grasped from the macroscopic aspect. This macroscopic grasp can reduce the multiple solutions in the pure seismic technology interpretation, and make the description result more in line with the geological law. In addition, the present application uses the stratum slicing to obviously improve the continuity of the lateral information. In the case of insufficient seismic data resolution, the geological interpretation accuracy of the seismic data is improved, and the geological body is clearly described on the plane.

[0028] 5. The channel description of the present application is relatively clear, and the lateral geological regularity is strong. The present application provides a high-efficiency means for helping the technical personnel to solve the prediction of the hidden channel sand body reservoir in the current complex lithologic background. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The flow chart of the method for finely describing the shallow discontinuous channel based on the seismic attribute of the present application;

[0030] Figure 2 The schematic diagram of the mathematical principle of the root mean square amplitude attribute;

[0031] Figure 3The figure shows the relationship between the amplitude of the simple harmonic vibration function and the numerical value in a small window;

[0032] Figure 4 Seismic reflection characteristics of the Xujiahe Formation profile Figure 1 ;

[0033] Figure 5 Seismic reflection characteristics of the Xujiahe Formation profile Figure 2 ;

[0034] Figure 6 Local root mean square amplitude attribute map of the Xujiahe Formation;

[0035] Figure 7 Root mean square amplitude attribute map of the Xujiahe 2 Member in the central Sichuan Basin;

[0036] Figure 8 Root mean square amplitude attribute map of the Xujiahe 4 Member in the central Sichuan Basin;

[0037] Figure 9 Root mean square amplitude attribute map of the Xujiahe 3 Member in the central Sichuan Basin;

[0038] Figure 10 Root mean square amplitude attribute map of the Xujiahe 6 Member in the central Sichuan Basin;

[0039] Figure 11 Stratigraphic slice superimposition map of the Xujiahe 2 Member in the central Sichuan Basin;

[0040] Figure 12 Stratigraphic slice superimposition map of the Xujiahe 4 Member in the central Sichuan Basin;

[0041] Figure 13 Stratigraphic slice superimposition map of the Xujiahe 3 Member in the central Sichuan Basin;

[0042] Figure 14 Stratigraphic slice superimposition map of the Xujiahe 6 Member in the central Sichuan Basin;

[0043] Figure 15 Stratigraphic profile display of the lower Xujiahe 3 Member in the study area;

[0044] Figure 16 Root mean square amplitude attribute and maximum peak amplitude attribute map of the Xujiahe 3 Member;

[0045] Figure 17 Stratigraphic slice attribute superimposition map of the Xujiahe 3 Member. DETAILED DESCRIPTION

[0046] The following detailed description illustrates by way of example, not by way of limitation, specific embodiments and examples that can be implemented as part of the present application. These implementations and examples do not necessarily represent all or the only ways in which the application can be implemented. Equivalent alterations and modifications to embodiments can be practiced as would be apparent to one of ordinary skill in the art having the benefit of this description. Thus, the scope of the application is not to be limited to the specific examples and implementations disclosed and can include practices or implementations that fall within the scope of the appended claims and their equivalents.

[0047] The ancient river channel is used as an oil and gas reservoir, and controls the migration and flow of oil and gas, has the advantages of high yield and good physical property, so the river channel identification is one of the important tasks of oil and gas exploration, but the effect of the river channel identification is closely related to the sedimentary geological characteristics and the seismic method. At present, the methods commonly used to identify the river channel mainly include seismic inversion, seismic attribute analysis, seismic frequency division and the like. These methods are all used to identify the river channel by using a single means, and the method is often limited by the seismic resolution. Meanwhile, aiming at the sand body of the target layer, the sand body is developed continuously, the lithology is pure and single, and the profile of the ancient river channel is clearly described, and the effect is good. However, with the increasing difficulty of the present reservoir prediction, the concealment of the river channel and the complexity of the sedimentary environment, the single method is difficult to clearly describe the profile of the river channel with poor continuity.

[0048] Compared with the prior art, the present application integrates multiple seismic prediction methods, uses the fusion seismic slice technology, and uses the commercial software to identify the concealed river channel boundary which cannot be clearly described by the conventional technology with poor continuity. The present application has the characteristics of high accuracy, simple method, easy operation and strong comprehensiveness as a whole, and has advancement.

[0049] The resolution of the seismic technology finally limits how much the technical personnel can obtain the stratum detail information from the seismic data, and also limits the ability of the seismic data to distinguish the sedimentary unit. The present application integrates the stratum slice technology, which can observe the whole appearance of the sedimentary body and macroscopically grasp the development characteristics of the sedimentary body. The macroscopic grasp can reduce the multiple solutions in the pure seismic technology interpretation, and is convenient for understanding the geological law. In addition, the present application uses the stratum slice to obviously improve the continuity of the lateral information, and can improve the geological interpretation accuracy of the seismic data in the case of insufficient seismic data resolution. The geological body can be clearly described in the plane.

[0050] Embodiment 1

[0051] As a preferred embodiment of the present application, referring to the drawings in the description Figure 1 The present embodiment discloses a method for finely describing a shallow discontinuous river channel based on seismic attributes, and the method comprises the following steps:

[0052] S1. Conduct fine-grained well-seismic calibration of channel sand bodies and study their seismic response; select three-dimensional seismic data with good imaging, high dominant frequency and wide frequency band in the study area for fine-grained layer interpretation.

[0053] S2. Select the root mean square amplitude attribute to predict the planar distribution of channel sand bodies;

[0054] S3. Use stratigraphic slicing technology to observe the characteristics of root mean square amplitude attributes on individual slices, and analyze and screen along the layer slices based on attribute information.

[0055] S4. Stack the selected slices in their original order;

[0056] S5. Obtain the planar distribution characteristics of the river boundary of the entire study area on the same plane, and further predict and analyze the sediment source and favorable reservoir distribution areas.

[0057] Example 2

[0058] As another preferred embodiment of the present invention, this embodiment further elaborates and supplements the technical solution of the present invention on the basis of the above embodiment 1. In this embodiment, in step S2, selecting the root mean square amplitude attribute to predict the planar distribution of the channel sand body specifically means, based on the stratigraphic interpretation, using the top and bottom layers of the target segment as control, extracting the root mean square amplitude attribute along the interlayer, and using the root mean square amplitude attribute to identify shallow channels.

[0059] In this embodiment, for complex lithological combinations of mud-encased sand or interbedded sand and mud, a suitable seismic attribute for characterizing the river channel is selected. (Refer to the appendix of the specification.) Figure 2 As shown, the conventional root-mean-square amplitude property takes the square root of the average of the squared amplitudes and then squares it before taking the average. This makes larger amplitude values ​​more prominent and therefore more sensitive to larger amplitude values. The formula is: ; This property is highly sensitive to amplitude changes and can reflect lithological variations well.

[0060] The sample values ​​in earthquake records are not amplitude values. However, in data interpretation, amplitude values ​​are often calculated using sample values ​​within a time window much smaller than the earthquake wavelength, or even using a single sample value as the amplitude value. For example... Figure 3 As shown, Figure 3 This is a schematic diagram showing the relationship between the amplitude value and the numerical value within a small window of a simple harmonic oscillation function. If the simple harmonic oscillation function is represented by A = A0cos(t), then A is the function value and A0 is the amplitude. Only at the maximum value of the function are the function value A and the amplitude value A0 equal.

[0061] Figure 3The function value in the time window can be studied by using four hours window a, b, c, d. It can be seen that the time window a and c are taken at the wave peak and wave trough, and the root mean square value or the average value of the absolute value in such time window can approximately represent the amplitude value. Strictly speaking, only the absolute value of the wave peak or wave trough is the amplitude value. In Figure 3 The value calculated in the time window b and d is obviously unable to represent the amplitude value, and is not equal to the value calculated in the time window a or c no matter how to calculate. However Figure 3 The amplitude value of the simple harmonic vibration function is invariable, so the value calculated by using the short time window cannot represent the amplitude value, and the change of the value cannot be used to study the change of the lithology.

[0062] As Figure 4 shown, the shallow channel is shown as obvious bright point reflection characteristics on the three-dimensional seismic profile, and the channel contour is difficult to be clearly depicted on the isochronous surface due to the influence of the complex lithology combination of the sand and mud interbed and mud wrapped sand by using the conventional channel identification technology along a certain time window. For the local bright point reflection of the sand and mud interbed, the root mean square amplitude attribute is selected by using the constant vertical length (time interval) between the layers or the region defined by two horizons, and the root mean square amplitude attribute is used to identify the shallow channel.

[0063] Embodiment 3

[0064] As another preferable embodiment of the present application, the embodiment is further supplemented and described in detail on the basis of the technical scheme of the present application in the above-mentioned embodiment 1 or embodiment 2. In the embodiment, the S3 step is specifically that, on the basis of the extracted root mean square amplitude attribute, the top and bottom horizons of the three-dimensional target layer of the study area are selected, that is, two isochronous interpretation horizons, and a plurality of thin layers are interpolated along the two relatively stable horizons by using the average division idea; the planar distribution characteristics are analyzed by using the attribute information displayed by a plurality of slices of the three-dimensional seismic data.

[0065] For the discontinuous channel characteristics of the complex lithology combination characteristics, the preferred root mean square amplitude attribute is used to depict the distribution of the local channel, but it is very difficult to depict the planar distribution characteristics of the channel of the target layer in the whole three-dimensional study area. Therefore, the method of combining the seismic attribute with the stratum slicing technology is used to depict the planar distribution characteristics of the channel of the study area.

[0066] The sliced data has been widely used in the interpretation of the three-dimensional seismic data, and the sliced data is the sample value of the seismic record, not the amplitude value, whether it is the horizontal slice or the along-layer slice and the stratum slice. According to the above discussion, the value calculated in the short time window is also difficult to represent the amplitude value, and only when the point is fully understood, the sliced data can be correctly interpreted.

[0067] Generally along layer slicing technique is an important technical means for studying seismic sedimentology. On the basis of extracting root mean square amplitude attribute, two isochronous interpretation horizons of a three-dimensional seismic work area are selected, and a number of thin layers are interpolated along the two relatively stable horizons in the thought of average division. The key is to analyze the planar distribution characteristics through attribute information displayed by a number of slices of a data volume.

[0068] This embodiment is to depict the local distribution of discontinuous channels based on the root mean square amplitude attribute in the amplitude attribute of a seismic data volume at a specific frequency. Only the star point or scattered distribution characteristics of the channels in the whole three-dimensional seismic work area can be clearly seen. On the basis of extracting the amplitude attribute, the top and bottom boundary horizons of the target layer are controlled for the scattered channel characteristics. According to the results of the spectral analysis of the seismic data of the target horizon, the amplitude slice of the seismic single volume corresponding to the main frequency of the seismic amplitude of the layer is selected. The amplitude slice of the best seismic single volume can better reflect the distribution characteristics of the sand body of the stratum. The stratum slices are divided in the longitudinal direction of the seismic single volume. The number of stratum slices is set according to the time requirement of the target layer in the division scheme. Through the browsing analysis of all the slices, the attribute characteristics of all the slices of the target layer are superimposed by using the Petrel software. Finally, the root mean square amplitude attribute extracted from the whole target layer is displayed on the same plan view to achieve the purpose of depicting the channels.

[0069] Further preferably, the attribute characteristics on each slice are browsed and analyzed, and the slices with clear local channel boundary characteristic information are selected. Then, the selected stratum slices of the target layer are superimposed in the original division order by using the Petrel software. The root mean square amplitude attribute extracted from the selected stratum slices of the whole target layer is displayed on the same plan view.

[0070] Embodiment 4

[0071] In this embodiment, the Xujiahe 3 lower, Xujiahe 4 and Xujiahe 6 members in the study area are thick sandstone deposits with multiple channel superimpositions. The well-to-seismic calibration results show that the high-quality sandstone (POR>6%) in the thick sandstone is a seismic response characteristic of a relatively top-valley bottom-high-peak on a low-frequency weak-amplitude seismic reflection background. Therefore, the maximum peak amplitude attribute is preferably selected to qualitatively predict the distribution of high-quality reservoir sand bodies in each stratum.

[0072] The Xujiahe 3 lower member in the study area has a large thickness of about 160-300m, and is mainly developed with sandstone with low GR value. According to the Xujiahe regional research, when the Xujiahe 3 lower member develops thick sand bodies, the seismic reflection characteristics are weak reflection (such as the seismic reflection characteristics shown in the description accompanying drawings). Figure 15When the sand and mud interbeds, the strong and weak amplitude phases are shown alternately. According to the curve characteristics, the lower segment of the third segment of Xujiahe Formation is divided into two segments, the lower segment is named as the lower segment of the third segment of Xujiahe Formation, and the upper segment is named as the upper segment of the third segment of Xujiahe Formation. The maximum peak amplitude attributes of the two segments are extracted respectively to depict the distribution of high-quality reservoir sand bodies.

[0073] The stratum slicing technology is limited by geological conditions, and therefore has certain limitations in actual application. Not every stratum slice can truly reflect the geological conditions, and therefore the selection of the slice should be optimized according to the geological understanding of the whole research area to reflect the changes of different geological bodies. The implementation method of the present application is described by taking the third segment of Xujiahe Formation as an example. As shown in the slice profile, four maximum peak amplitude attributes and root mean square amplitude attributes are equally divided along the top and bottom surfaces, and the stratum thickness should not be too large to avoid the time penetration phenomenon.

[0074] As shown in the description accompanying drawings, Figure 16 Fig. 1 is a slice profile, wherein ①, ②, ③ and ④ are the amplitude attributes corresponding to the slices from bottom to top, and the slice attributes are superimposed according to the order of the slices (as shown in Fig. 2) to depict the discontinuous channel under the background of mud-bund sand or thin mud and sand interbeds. Figure 17

[0075] Embodiment 5

[0076] As another embodiment of the present application, the method and the root mean square amplitude attribute algorithm principle of the commercial software in the above-mentioned embodiments 1-3 are used to process and compare the seismic data of the three-dimensional work area of the third segment of Xujiahe Formation in the Dongzhong area of Sichuan Basin.

[0077] Figure 4 and Figure 5 The three-dimensional seismic data of the target layer of Xujiahe Formation and the seismic reflection characteristics are good, the main frequency of the seismic data is high, the frequency band range is wide (the main frequency is about 35 Hz, and the frequency band is 10-70 Hz), the main reflection is medium and weak amplitude, and the channel reservoir sand body has a local bright spot reflection of strong amplitude.

[0078] As shown in the description accompanying drawings, Figure 6 For the mud and sand interbeds and the channel sand body of mud-bund sand of Xujiahe Formation, the local bright spot reflection characteristics corresponding to the wave trough and the wave peak are shown on the seismic data, and the boundaries of the channel are depicted by optimizing the root mean square amplitude attribute.

[0079] The three-dimensional seismic data of the target layer of Xujiahe Formation and the seismic reflection characteristics are good, the main frequency of the seismic data is high, the frequency band range is wide (the main frequency is about 35 Hz, and the frequency band is 10-70 Hz), the main reflection is medium and weak amplitude, and the channel reservoir sand body has a local bright spot reflection of strong amplitude. Figures 7-10 ​It is shown that the bright point feature of the channel sand body of Xujiahe Formation is extracted by the root mean square amplitude attribute in the whole three-dimensional area of Dongdaying in Zhongjiang. The channel feature of the whole three-dimensional area is in a scattered or star point shape, and the channel boundary is not significant. On the basis of the three-dimensional seismic horizon interpretation of Dongdaying in Zhongjiang, the root mean square amplitude attribute extraction method and the stratum slice technology are combined to control the internal top and bottom horizons of Xujiahe in the whole three-dimensional area, and 10 slices are cut. The channel features of the integrated three-dimensional area are described on the plane by the mutual superposition of the attribute slices (as shown in Figures 11-14 The yellow-red is the bright point reflection boundary, that is, the distribution feature of the channel, and is relatively clear.

[0080] Although 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 can be made therein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A method for fine description of shallow discontinuous channel based on seismic attributes, characterized in that: The shallow discontinuous channel refers to a delta front underwater discontinuous channel with mud-sand interbedding and mud-bundled sandstone lithologic combination; the method for finely depicting the shallow discontinuous channel based on seismic attributes comprises the following steps: S1, carry out well-seismic fine calibration of channel sand body and seismic response research of channel sand body; S2, select root mean square amplitude attribute to predict the planar distribution of channel sand body, and based on horizon interpretation, control the top and bottom horizons of the target layer, extract root mean square amplitude attribute along the layers, and identify the shallow channel by using the root mean square amplitude attribute; S3, observe the characteristics of root mean square amplitude attribute on a single slice by using strata slicing technology, and analyze and screen the slices according to attribute information; based on the extraction of root mean square amplitude attribute, select the top and bottom horizons of the target layer of the study area, that is, two isochronous interpretation layers, and interpolate several thin layers according to the idea of average division; analyze the planar distribution characteristics by attribute information displayed by several slices of three-dimensional seismic data; based on the extraction of root mean square amplitude attribute, control the top and bottom horizons of the target layer by using three-dimensional seismic data, select the seismic single frequency body corresponding to the main frequency of the seismic amplitude of the layer and having boundary characteristics in the planar distribution of amplitude according to the results of frequency spectrum analysis of the target layer of the study area, and divide the slices in the longitudinal direction of the seismic single frequency body; S4, superimpose the screened slices according to the original order of the slices, display the root mean square amplitude attribute extracted from the strata slices screened from the entire target layer on the same planar graph, and superimpose the amplitude variation characteristics on the strata slices screened from the entire target layer; S5, obtain the planar distribution characteristics of the channel boundary of the entire study area on the same planar graph, and further predict and analyze the sediment source and favorable reservoir distribution area.

2. The method for finely depicting the shallow discontinuous channel based on the seismic attribute according to claim 1, characterized in that: The division scheme of the entire target layer sets the number of strata slices according to the time requirement of the target layer.

3. The method for fine description of shallow discontinuous channel based on seismic attribute according to claim 2, characterized in that: The analysis and screening in the step S3 specifically refers to screening the slices with clear local channel boundary characteristic information by browsing and analyzing the attribute characteristics on each slice.

4. The method for finely depicting the shallow discontinuous channel based on the seismic attribute according to any one of claims 1-3, characterized in that: In the step S4, the commercial software is used to superimpose the strata slices screened from the target layer according to the original division order.

5. The method for fine description of shallow discontinuous channel based on seismic attribute according to claim 4, characterized in that: The commercial software is Petrel software.

6. The method for finely depicting the shallow discontinuous channel based on the seismic attribute according to any one of claims 1-3, characterized in that: In the step S1, select three-dimensional seismic data with good imaging, high main frequency and wide frequency band range in the study area for fine horizon interpretation.

7. The method for fine description of shallow discontinuous channel based on seismic attribute according to claim 6, characterized in that: The high main frequency and wide frequency band range refer to a main frequency of 35 Hz and a frequency band of 10-70 Hz.

8. The method for finely depicting the shallow discontinuous channel based on the seismic attribute according to any one of claims 1-3, characterized in that: The root mean square amplitude attribute is extracted through layers with constant vertical length or the region defined between two horizons for the local mud-sand interbedded channel highlight reflection.

9. The method for finely depicting the shallow discontinuous channel based on the seismic attribute according to any one of claims 1-3, characterized in that: The main frequency of the seismic single frequency body is higher than the main frequency of the seismic amplitude of the target layer.

10. The method for finely depicting a shallow discontinuous channel based on seismic attributes according to any one of claims 1-3, characterized in that: The superimposed planar graph identifies the channel distribution characteristics by the boundary of yellow-red highlight reflection.

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