Method for identifying a foreset reflection structure

Abstract

The application discloses a method for identifying a progradation reflection structure, and belongs to the technical field of seismic exploration processing. The method comprises the following steps: performing fractional order differentiation on a seismic data volume according to a first preset order to obtain a fractional order differentiated seismic data volume; performing flattening processing on the fractional order differentiated seismic data volume to obtain a first seismic data volume; determining a first preset surface based on the first seismic data volume; performing extraction processing on the fractional order differentiated seismic data volume based on the first preset surface to obtain a first layer-following slice; and determining a progradation reflection structure based on the first seismic data volume and the first layer-following slice. The method can more accurately identify the progradation reflection structure.

Description

Technical Field

[0001] This application relates to the field of seismic exploration and processing technology, and in particular to a method for identifying anterior reflection structures. Background Technology

[0002] In seismic exploration, progradational reflection structures are an important feature on seismic profiles. These structures include overlapping, progradational, and basaltic layers. Progradational reflection structures can reflect the source direction and hydrodynamic magnitude, and determine sequence stratigraphy and systems tract boundaries.

[0003] In related technologies, seismic profiles are mainly obtained through seismic data volumes, and the morphological features reflected by the seismic profiles are used to identify the anterior reflection structures.

[0004] However, when identifying prograde reflection structures, current seismic profiles cannot present the dominant frequency bands of morphological characteristics and cannot intuitively reflect the orientation of prograde reflection structures, thus affecting the identification of prograde reflection structures. Summary of the Invention

[0005] In view of this, this application provides a method for identifying front-integral reflection structures, which can more accurately identify front-integral reflection structures.

[0006] Specifically, the following technical solutions are included:

[0007] This application provides a method for identifying an anterior reflection structure, the method comprising:

[0008] Based on the first preset order, the seismic data volume is subjected to fractional derivative to obtain fractional derivative seismic data volume.

[0009] The fractional-order differential seismic data volume is flattened to obtain the first seismic data volume;

[0010] Based on the first seismic data volume, a first preset surface is determined;

[0011] Based on the first preset surface, the fractional differential seismic data volume is extracted and processed to obtain the first slice along the layer;

[0012] Based on the first seismic data volume and the first layer slice, the pre-accretion reflection structure is determined.

[0013] In some embodiments, performing fractional-order differentiation on the seismic data volume according to a first preset order to obtain a fractional-order differential seismic data volume includes:

[0014] The seismic data volume is subjected to Fourier transform processing to obtain the seismic data volume in the frequency domain;

[0015] Based on the first preset order, the frequency domain seismic data volume is subjected to fractional-order differentiation to obtain the fractional-order differential seismic data volume.

[0016] In some embodiments, the frequency domain seismic data volume is subjected to fractional derivatives according to the following formula:

[0017]

[0018] In the formula: D α This represents the α-order differential, and f(t) represents the seismic data volume. rq F(f) represents the frequency of the seismic data volume, ω represents the angular frequency of the seismic data volume, and F(f) represents the frequency of the seismic data volume. rq ) represents the frequency of the seismic data volume in the frequency domain, t represents time, and k represents the rotation parameter; when k is 0, it means no phase rotation is performed; when k is 1, it means phase rotation is performed.

[0019] In some embodiments, the first seismic data volume has linear features of a lake basin bottom shape during the sedimentary period and pre-accretionary layer features of a pre-accretionary reflection structure. Determining a first preset surface based on the first seismic data volume includes:

[0020] Based on the linear features of the lake basin bottom shape during the depositional period or the pre-accretion layer features of the pre-accretion reflection structure, the first preset surface is determined, wherein the first preset surface is a surface parallel to the lake basin bottom shape during the depositional period or a surface that intersects with the pre-accretion layers of all pre-accretion reflection structures.

[0021] In some embodiments, the step of extracting and processing the fractional-order differential seismic data volume according to the first preset surface to obtain a first slice along the layer includes:

[0022] Based on the plane parallel to the lake basin bottom shape during the deposition period or the plane intersecting with the pre-accretion layers of all pre-accretion reflection structures, the fractional-order differential seismic data volume is extracted and processed to obtain the first layer slice.

[0023] In some embodiments, determining the pre-accretion reflection structure based on the first seismic data volume and the first layer slice includes:

[0024] Based on the first seismic data volume, the dominant frequency band of the pre-accretionary reflection structure is determined;

[0025] Based on the first rock stratum slice, the orientation of the pre-accretionary reflection structure is determined;

[0026] The front accretion reflection structure is determined based on its dominant frequency band and orientation.

[0027] In some embodiments, the method further includes:

[0028] According to the second preset order, the seismic data volume is integrated by fractional order to obtain the fractional integral seismic data volume, wherein the seismic data volume is integrated by fractional order according to the following calculation formula;

[0029]

[0030] In the formula: I α This represents the calculation of the α-order integral, where f(t) represents the volume of seismic data. rq F(f) represents the frequency of the seismic data volume, ω represents the angular frequency of the seismic data volume, and F(f) represents the frequency of the seismic data volume. rq The value ) represents the frequency of the seismic data volume in the frequency domain, t represents time, and k represents the rotation parameter; when k is 0, it means no phase rotation is performed; when k is 1, it means phase rotation is performed.

[0031] The fractional integral seismic data volume is flattened to obtain the second seismic data volume;

[0032] Based on the second seismic data volume, a second preset surface is determined;

[0033] Based on the second preset surface, the fractional integral seismic data volume is extracted and processed to obtain the second slice along the layer;

[0034] The anterior reflection structure is determined based on the first seismic data volume, the second seismic data volume, the first layer slice, and the second layer slice.

[0035] In some embodiments, after extracting the fractional-order differential seismic data volume according to the first preset surface to obtain a first slice along the layer, the method further includes:

[0036] Based on well logging data, drilling data, the first seismic data volume, and the first stratigraphic slice, the progradation dip angle, paleowater depth, progradation stage, stratigraphic accretion rate, stratigraphic progradation rate, and main depositional direction are determined.

[0037] In some embodiments, determining the progradation dip angle, paleowater depth, progradation stage, stratigraphic accretion rate, progradation rate, and main depositional direction based on well logging data, drilling data, the first seismic data volume, and the first stratigraphic slice includes:

[0038] Based on the well logging data, the drilling data, and the first seismic data volume, determine the progradation dip angle and the paleowater depth;

[0039] Based on the well logging data, the drilling data, the first seismic data volume, and the first stratigraphic slice, the development stage, the stratigraphic accretion rate, the stratigraphic progradation rate, and the main depositional direction are determined.

[0040] In some embodiments, determining the progradation dip angle and the paleowater depth based on the well logging data, the drilling data, and the first seismic data volume includes:

[0041] Based on the first seismic data volume, the forward inclination angle is calculated;

[0042] Determine the formation compaction coefficient based on drilling and logging data;

[0043] The depth of the paleowater body is calculated based on the compaction coefficient and the first seismic data volume.

[0044] The method for identifying anterior accretion reflection structures provided in this application involves fractionally differentiating a seismic data volume according to a first preset order to obtain a fractional-differential seismic data volume. This fractional-differential data volume is then flattened to obtain a first seismic data volume, which in turn determines a first preset surface. Based on this first preset surface, the fractional-differential seismic data volume is further extracted to obtain a first bedding slice. Finally, the anterior accretion reflection structure is determined using the first seismic data volume and the first bedding slice. Because the first seismic data volume reflects the dominant frequency band of the anterior accretion reflection structure, and the first bedding slice can more intuitively reflect the orientation of the anterior accretion reflection structure, the method for identifying anterior accretion reflection structures provided in this application can more accurately identify such structures. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A flowchart illustrating a method for identifying a front-integral reflection structure provided in this application embodiment;

[0047] Figure 2 A flowchart illustrating a method for identifying a pre-integral reflection structure provided in this application, which involves performing fractional-order differential on a seismic data volume according to a first preset order to obtain a fractional-order differential seismic data volume;

[0048] Figure 3A flowchart illustrating the method for flattening fractional differential seismic data volumes to obtain a first seismic data volume in a method for identifying pre-integral reflection structures provided in this application embodiment;

[0049] Figure 4(a) is a diagram showing the effect of a seismic profile obtained using a method in the related art according to an embodiment of this application;

[0050] Figure 4(b) is a rendering of the seismic profile of the fractional differential seismic data volume obtained by the identification method of the pre-integral reflection structure provided in the embodiment of this application;

[0051] Figure 5 An image showing the effect of a seismic profile of the first seismic data volume obtained by the identification method of the pre-integral reflection structure provided in an embodiment of this application.

[0052] Figure 6 An image showing the effect of the first slice obtained by the recognition method using the pre-integral reflection structure provided in the embodiments of this application;

[0053] Figure 7 A flowchart illustrating another method for identifying a pre-integral reflection structure provided in this application embodiment;

[0054] Figure 8 The flowchart illustrates another method for identifying pre-integral reflection structures provided in this application, which involves performing fractional-order differentiation and fractional-order integration on the seismic data volume according to a first preset order and a second preset order, respectively, to obtain fractional-order differential seismic data volume and fractional-order integral seismic data volume. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] In the margins of oceans and lakes, continental slopes, and carbonate platform margins, sediments undergo deposition and downdipping; this progressive process of deposition and downdipping is called progradation. In seismic exploration, exploration of these areas yields corresponding seismic data volumes. On seismic profiles determined based on these data volumes, progradational reflection structures corresponding to the progradation phenomenon can be observed. Progradational reflection structures include top-sedimentary, progradational, and bottom-sedimentary layers. These structures reflect the source direction and hydrodynamic magnitude, determine sequence stratigraphy and systems tract boundaries, and play an irreplaceable role in understanding the sedimentary filling processes of oceans and lacustrine basins, the coupled tectonic-climate-sedimentary response, basin sedimentary filling processes, and deep-water reservoir prediction. They are of great significance for the processing and analysis of seismic data.

[0057] In related technologies, the identification of anterior accretion reflection structures is mainly based on the linear morphological features in seismic profiles obtained from seismic data volumes. However, the seismic profiles obtained in these technologies cannot depict the anterior accretion reflection structures in sufficient detail, thus affecting the accurate identification of these structures.

[0058] Figure 1 This is a flowchart illustrating a method for identifying a front-integral reflection structure, as provided in an embodiment of this application.

[0059] See Figure 1 The method includes:

[0060] Step 101: Perform fractional-order differentiation on the seismic data volume according to the first preset order to obtain fractional-order differential seismic data volume.

[0061] This fractional-order differential seismic data volume includes both high-frequency data that can reflect the details of the prograde reflection structure and low-frequency data that can reflect the basic orientation and changes of the prograde reflection structure, thus providing a more comprehensive reflection of the morphological information of the prograde reflection structure.

[0062] In some embodiments, the value of the first preset order can be an integer or a fraction, which can be determined experimentally, and its value is not specifically limited in this application embodiment. For example, the value of the first preset order can be 1.6.

[0063] See Figure 2 This step may include the following sub-steps:

[0064] Step 1011: Perform Fourier transform on the seismic data volume to obtain the seismic data volume in the frequency domain.

[0065] The essence of fractional differentiation of seismic data volume is to perform fractional differentiation on the frequency of seismic data volume. Since seismic data volume itself is in the time domain, it is necessary to first perform Fourier transform on the original time domain seismic data volume to obtain the frequency domain seismic data volume.

[0066] In some embodiments, the seismic data volume in the frequency domain is obtained according to the following calculation formula:

[0067]

[0068] In the formula: F(f rq ) represents the seismic data volume in the frequency domain, f(t) represents the seismic data volume, ω represents the angular frequency of the seismic data volume, and t represents time.

[0069] Step 1012: Based on the first preset order, perform fractional derivative on the seismic data volume in the frequency domain to obtain the fractional derivative seismic data volume.

[0070] In some embodiments, the frequency domain seismic data volume is fractionally differentiated according to the following calculation formula.

[0071]

[0072] In the formula: D α This represents the α-order differential, where f(t) represents the seismic data volume. rq F(f) represents the frequency of the seismic data volume, ω represents the angular frequency of the seismic data volume, and F(f) represents the frequency of the seismic data volume. rq ) represents the frequency of the seismic data volume in the frequency domain, t represents time, and k represents the rotation parameter; when k is 0, it means no phase rotation is performed; when k is 1, it means phase rotation is performed.

[0073] It should be noted that the setting of k is to achieve the rotation of the phase. In practical applications, in order to keep the phase of the seismic data volume before and after the fractional derivative consistent, k is generally set to 0.

[0074] Step 102: Flatten the fractional-order differential seismic data volume to obtain the first seismic data volume.

[0075] By flattening the fractional-order differential seismic data volume, the first seismic data volume can be obtained. This first seismic data volume can restore the morphological characteristics of the lake basin bottom, and its seismic profile reflects the dominant frequency band of the progradational reflection structure.

[0076] In some embodiments, flattening of fractional-order differential seismic data volumes can be achieved using the flattening function of Geoeast, Landmark, or Geoview software.

[0077] See Figure 3 This step can specifically include the following sub-steps:

[0078] Step 1021: Obtain the extension line of the top-layer reflection structure.

[0079] Among them, the top-accretion layer reflection structure is the upper section of the pre-accretion reflection structure. Its direction is relatively gentle and its changes are small, which can better reflect the morphological characteristics of the lake basin bottom during the deposition period.

[0080] Step 1022: Based on the extension lines of the topsoil reflection structure, the fractional-order differential seismic data volume is flattened to obtain the first seismic data volume.

[0081] Among them, the first seismic data volume has linear features of a lake basin bottom shape during the sedimentary period and pre-accretionary layer features of a pre-accretionary reflection structure.

[0082] For example, Figure 4(a) is an image of a seismic profile obtained using a method in the related art according to an embodiment of this application, and Figure 4(b) is an image of a seismic profile of a first seismic data volume obtained using a method for identifying pre-accretion reflection structures according to an embodiment of this application, wherein the first preset order is 1.6. By comparing Figure 4(a) and Figure 4(b), it can be seen from the areas circled by the corresponding black solid circles in the two figures that the morphological information of the seismic profile of the first seismic data volume obtained using the method for identifying pre-accretion reflection structures is richer and more detailed.

[0083] Step 103: Determine the first preset surface based on the first seismic data volume.

[0084] Determining the first preset surface facilitates subsequent extraction and processing of fractional differential seismic data volumes.

[0085] This step can be achieved as follows: based on the linear features of the lake basin bottom shape during the depositional period or the pre-accretion layer features of the pre-accretion reflection structure, a first preset surface is determined, wherein the first preset surface is a surface parallel to the lake basin topography during the depositional period or a surface intersecting with the pre-accretion layers of all pre-accretion reflection structures.

[0086] Furthermore, based on the linear characteristics of the lake basin bottom shape during the depositional period, a surface parallel to the lake basin bottom shape during the depositional period can be determined; based on the characteristics of the pre-accretionary reflective layers, a surface intersecting with the pre-accretionary reflective layers of all pre-accretionary reflective structures can be determined.

[0087] For example, Figure 5 A rendering of the seismic profile of the first seismic data volume obtained using the identification method for pre-accretion reflection structures provided in an embodiment of this application. See also... Figure 5As can be seen, the dashed line at Tk indicates a clear linear feature, indicating high energy in the seismic data. It represents the trend of the lake basin bottom morphology during the depositional period. The dashed line at Tx represents the dashed line intersecting with the pre-accretionary layers of all pre-accretionary reflection structures. Figure 5 In the diagram, Tk, Tj9, Tj, and Tt7, marked with dashed lines, represent the Cretaceous basal reflection structure, the Jurassic Yan'an Formation Yan 9 basal reflection structure, the Jurassic basal reflection structure, and the Triassic Yanchang Formation Chang 7 mudstone top reflection structure, respectively. fs1-fs9, marked with dashed lines, represent the progradational reflection structures of the Yanchang Formation. Within the progradational reflection structures fs1-fs9, the upper section (apical layer) of each structure is nearly horizontal, the middle section (progradational layer) is a progradational slope, and the lower section (basal layer) coincides with or is parallel to the reflection from the lake basin floor (i.e., Tt7 marked with dashed lines). Taking fs3 marked with dashed lines as an example, fs3 is located near dashed line Tx, and its... Figure 5 The general direction of the structure is from the upper left to the lower right, forming a horizontally flipped "S" shape. The dashed line in the upper left part of the pre-accretionary reflection structure fs3 is the upper section of the pre-accretionary reflection structure fs3, that is, the relatively gentle top accretionary layer. The dashed line near the intersection of the pre-accretionary reflection structure fs3 and the dashed line Tx is the middle section of the pre-accretionary reflection structure fs3, that is, the relatively steep pre-accretionary layer. The dashed line in the lower right part of the pre-accretionary reflection structure fs3 is the lower section of the pre-accretionary reflection structure fs3, that is, the bottom accretionary layer, which is relatively gentle and coincides with the bottom of the lake basin (that is, Tt7 marked by the dashed line).

[0088] Step 104: Based on the first preset surface, extract and process the fractional differential seismic data volume to obtain the first slice along the layer.

[0089] Based on the first preset surface, the fractional differential seismic data volume is extracted and processed to obtain the first layer slice, which can more intuitively reflect the orientation of the pre-accretion reflection structure.

[0090] In some embodiments, the fractional differential seismic data volume can be extracted using the extraction functions of software such as Geoeast, Landmark, or Geoview.

[0091] In this embodiment of the application, the step specifically includes: extracting and processing the fractional-order differential seismic data volume based on a surface parallel to the lake basin bottom shape during the deposition period or a surface intersecting with the pre-accretion layers of all pre-accretion reflection structures to obtain a first layer slice.

[0092] When extracting fractional-order differential seismic data from a surface parallel to the lake basin bottom shape during the depositional period to obtain the first layer slice, the following steps can be followed:

[0093] The first step involves extracting the fractional-order differential seismic data volume based on a surface parallel to the lake basin bottom shape during the sedimentation period, resulting in the first extracted seismic data volume.

[0094] The second step is to extract and process the first extracted seismic data volume to obtain the first slice along the layer.

[0095] Extracting the first seismic data volume allows for the segmentation of the portion containing pre-accretionary reflection structures, which is represented as a first bedding slice. The size of this first bedding slice is determined by the area of ​​multiple pre-accretionary reflection structures; in other words, the first bedding slice can include multiple pre-accretionary reflection structures.

[0096] When extracting the fractional-order differential seismic data volume based on the surface that intersects with all pre-accretionary reflection structures to obtain the first layer slice, the following steps can be followed:

[0097] The first step involves extracting the fractional-order differential seismic data volume based on the surface that intersects with the pre-accretion layers of all pre-accretion reflection structures, resulting in the second extracted seismic data volume.

[0098] The second step is to extract and process the second seismic data volume to obtain the first slice along the layer.

[0099] Extracting the second seismic data volume allows for the segmentation of the portion containing pre-accretionary reflection structures, which is represented as a first bedding slice. The size of this second bedding slice is determined by the area of ​​multiple pre-accretionary reflection structures; in other words, the second bedding slice can include multiple pre-accretionary reflection structures.

[0100] In practical applications, in order to obtain as many precumbrance reflection structures as possible, the fractional differential seismic data volume is extracted and processed based on the surface that intersects with the precumbrance layers of all precumbrance reflection structures to obtain the first layer slice, so as to more completely reflect all precumbrance reflection structures.

[0101] For example, Figure 6 An image showing the effect of the first slice obtained by the recognition method using the pre-integral reflection structure provided in this embodiment of the application. See also... Figure 6 The linear features on the first slice are the orientation lines of the foreland surface, representing the orientation direction of the foreland surface. The dip direction of the foreland surface is vertical and points towards the direction of the lake basin, which is the direction of the source.

[0102] It should be noted that the forelandic surface is the surface where the forelandic reflection structure is located. The strike line of the forelandic surface refers to the linear feature representing the strike of the forelandic surface along the layer slice, which is also an approximate shoreline (or continental margin), and the shoreline is located on the landward side of the strike line of the forelandic surface. The dip direction of the forelandic surface refers to its vertical strike along the layer slice, pointing towards the lake basin, which is also the source direction.

[0103] Step 105: Based on the first seismic data volume and the first layer slice, determine the pre-accretion reflection structure.

[0104] The first seismic data volume reflects the dominant frequency band of the progradational reflection structure, and the first bedding slice can more intuitively reflect the orientation of the progradational reflection structure. Therefore, based on the first seismic data volume and the first bedding slice, the progradational reflection structure can be determined.

[0105] This step can be implemented as follows: Based on the first seismic data volume, determine the dominant frequency band of the progradational reflection structure; based on the first rock stratum slice, determine the orientation of the progradational reflection structure; based on the dominant frequency band and orientation of the progradational reflection structure, determine the progradational reflection structure.

[0106] In some embodiments, the pre-accretionary reflection structure can be identified and interpreted by combining the inline direction of the first seismic data volume and the Xline direction perpendicular to the survey line, provided that the orientation of the pre-accretionary reflection structure is determined.

[0107] Once the preaccretionary reflection structure is identified, it can be marked to facilitate subsequent earthquake interpretation.

[0108] For example, Figure 6 The dashed lines fs1-fs8 shown are the markers for the pre-integral reflection structure.

[0109] It should be noted that the types of front-accretion reflection structures can be divided into nine types: oblique type, tangential oblique type, tangential oblique random type, asymmetric top-thick type, asymmetric bottom-thick type, divergent S-type, symmetrical S-type, random S-type, and composite type.

[0110] For example, Figure 6 The type of the pre-integral reflection structure is symmetrical S-shaped.

[0111] To facilitate the identification and interpretation of anterior reflection structures by seismic interpreters, in some embodiments, the method for identifying anterior reflection structures provided in this application further includes:

[0112] Based on well logging data, drilling data, the first seismic data volume, and the first stratigraphic slice, the progradation dip angle, paleowater depth, progradation stage, stratigraphic accretion rate, stratigraphic progradation rate, and main depositional direction were determined.

[0113] By utilizing well logging data, drilling data, the first seismic data volume, and the first layer slice, quantitative information on the anterior accretion reflection structure is determined, thereby enabling better analysis of the anterior accretion reflection structure.

[0114] In some embodiments, the foregradation dip angle and paleowater depth are determined based on well logging data, drilling data, and a first seismic data volume. The specific implementation is as follows: the foregradation dip angle is calculated based on the first seismic data volume; the formation compaction coefficient is determined based on drilling data and well logging data; and the paleowater depth is calculated based on the compaction coefficient and the first seismic data volume.

[0115] The first seismic data volume includes the foreland curvature and morphological characteristics of the foreland reflection structure, while the well logging and drilling data include stratigraphic data, sandstone and mudstone content data, and P-wave velocity data.

[0116] In some embodiments, the forward product tilt angle is obtained according to the following formula:

[0117]

[0118] in, represents the pre-product inclination angle, x represents the difference in vertical depth between two points in the pre-product structure, s represents the horizontal distance between two points in the pre-product structure; atan() represents the arctangent function.

[0119] For example, Figure 5 The pre-integral tilt angle at the upper end (the most shaky segment) of the pre-integral layer of the pre-integral reflection structure fs4 in the middle is...

[0120] In some embodiments, the paleowater depth is obtained according to the following formula:

[0121] h=v(t1-t2) / (2(1+g))

[0122] Where h represents the paleowater depth, v represents the average velocity of the strata, t1 represents the time value of the basal layer of the pre-accretionary reflection in the first seismic data volume, t2 represents the time value of the apical layer of the pre-accretionary reflection in the first seismic data volume, and g represents the stratum compaction coefficient.

[0123] For example, the average formation velocity in well logging and drilling data is 3800 m / s. In the forelandic sedimentary body at the delta front, sandstone accounts for 30%–60% and mudstone for 40%–70%. The final compaction coefficient of pure sandstone is 0.2, and that of pure mudstone is 0.6–0.7. Therefore, the compaction coefficient g is taken as 0.3. Figure 5The paleowater depth at the upper end (the most turbulent segment) of the fs4 pre-stratum is h = v(t1-t2) / (2(1+g)) = 3800 × (1213-1119) / 2 × (1+0.3) = 244.4 m. The chosen t1 and t2 are the time values ​​corresponding to the two points where fs4 experiences the most turbulence.

[0124] In some embodiments, the development stage, formation accretion rate, formation progradation rate, and main depositional direction are determined based on well logging data, drilling data, a first seismic data volume, and a first stratigraphic slice.

[0125] Among them, the developmental stages of the progradational reflection structure, or simply progradational developmental stages, refer to the number of strong and continuous progradational reflections on the seismic profile and the number of strong and continuous progradational surface strike lines along the layer slices.

[0126] It should be noted that the stratigraphic accretion rate refers to the vertical increase in stratigraphic strata in the current phase relative to the previous phase on the progradational profile and along the bedding plane; the stratigraphic progradation rate refers to the horizontal increase in stratigraphic strata in the current phase relative to the previous phase on the progradational profile and along the bedding plane. The main depositional direction refers to the direction in which the maximum horizontal increase in stratigraphic strata occurs in the current phase relative to the previous phase on the plane.

[0127] For example, Figure 5 and Figure 6 The main developmental stages of the anterior accumulation reflection structure in the extended group are 8, namely fs1-fs8. Therefore, fs5 adds 40m to the previous stage fs4, and the anterior accumulation is 5205m.

[0128] Therefore, the method for identifying prograde reflection structures provided in this application embodiment obtains a fractional-order differential seismic data volume by performing fractional-order differentiation on the seismic data volume according to a first preset order. This fractional-order differential seismic data volume is then flattened to obtain a first seismic data volume, which in turn determines a first preset surface. Based on this first preset surface, the fractional-order differential seismic data volume is further extracted to obtain a first bedding slice. Finally, using the first seismic data volume and the first bedding slice, the prograde reflection structure can be determined. The first seismic data volume reflects the dominant frequency band of the prograde reflection structure, and the first bedding slice more intuitively reflects the orientation of the prograde reflection structure. Therefore, the method for identifying prograde reflection structures provided in this application embodiment can more accurately identify prograde reflection structures.

[0129] Figure 7 A flowchart illustrating another method for identifying a pre-integral reflection structure provided in an embodiment of this application. See also... Figure 7 The method includes:

[0130] Step 201: Based on the first preset order and the second preset order, perform fractional derivative and fractional integral operations on the seismic data volume to obtain fractional derivative seismic data volume and fractional integral seismic data volume, respectively.

[0131] By using the first and second preset orders to perform fractional differentiation and fractional integration on the seismic data volume, not only can a fractional differential seismic data volume be obtained, but also a fractional integral seismic data volume can be obtained to assist in the identification of pre-integral reflection structures from the fractional differential seismic data volume.

[0132] The fractional differential seismic data volume includes both high-frequency data that reflects the details of the precumbratory reflection structure and low-frequency data that reflects the basic orientation and changes of the precumbratory reflection structure. The fractional integral seismic data volume includes low-frequency data that reflects the basic orientation and changes of the precumbratory reflection structure. Therefore, by combining the fractional differential seismic data volume and the fractional integral seismic data volume, the morphological information of the precumbratory reflection structure can be reflected more comprehensively.

[0133] In some embodiments, the values ​​of the first preset order and the second preset order can both be integers or fractions, which can be determined by experiments. Their values ​​are not specifically limited in this embodiment of the application.

[0134] See Figure 8 This step may include the following sub-steps:

[0135] Step 2011: Perform Fourier transform on the seismic data volume to obtain the seismic data volume in the frequency domain.

[0136] Since performing fractional differentiation or fractional integration on seismic data volume essentially involves performing fractional differentiation or fractional integration on the frequency of the seismic data volume, and seismic data volume itself is in the time domain, it is necessary to first perform Fourier transform on the original time domain seismic data volume to obtain the frequency domain seismic data volume.

[0137] In some embodiments, the seismic data volume in the frequency domain is obtained according to the following calculation formula:

[0138]

[0139] In the formula: F(f rq ) represents the seismic data volume in the frequency domain, f(t) represents the seismic data volume, ω represents the angular frequency of the seismic data volume, and t represents time.

[0140] Step 2012: Based on the first preset order and the second preset order, perform fractional derivative and fractional integral operations on the seismic data volume in the frequency domain to obtain fractional derivative seismic data volume and fractional integral seismic data volume.

[0141] In some embodiments, the frequency domain seismic data volume is fractionally differentiated according to the following calculation formula.

[0142]

[0143] In the formula: D α This represents the α-order differential, where f(t) represents the seismic data volume. rq F(f) represents the frequency of the seismic data volume, ω represents the angular frequency of the seismic data volume, and F(f) represents the frequency of the seismic data volume. rq ) represents the frequency of the seismic data volume in the frequency domain, t represents time, and k represents the rotation parameter; when k is 0, it means no phase rotation is performed; when k is 1, it means phase rotation is performed.

[0144] In some embodiments, the seismic data volume in the frequency domain is integraled according to the following formula.

[0145]

[0146] In the formula: I α This represents the α-order integral, where f(t) represents the seismic data volume. rq F(f) represents the frequency of the seismic data volume, ω represents the angular frequency of the seismic data volume, and F(f) represents the frequency of the seismic data volume. rq ) represents the frequency of the seismic data volume in the frequency domain, t represents time, and k represents the rotation parameter; when k is 0, it means no phase rotation is performed; when k is 1, it means phase rotation is performed.

[0147] Prior to this step, three-dimensional seismic data can be acquired in the study area, and a seismic data volume can be constructed based on the three-dimensional seismic data.

[0148] It is understandable that the seismic data volume is a three-dimensional seismic data volume.

[0149] Step 202: Flatten the fractional differential seismic data volume and the fractional integral seismic data volume respectively to obtain the first seismic data volume and the second seismic data volume.

[0150] Both the first and second seismic data volumes can reconstruct the morphological characteristics of the lake basin bottom and reflect the dominant frequency bands of the anterior accretion reflection structure.

[0151] In some embodiments, the flattening of fractional differential seismic data volumes and fractional integral seismic data volumes can be achieved using the flattening function of Geoeast, Landmark, or Geoview software.

[0152] Step 203: Based on the first seismic data volume and the second seismic data volume, determine the first preset surface and the second preset surface respectively.

[0153] By determining the first and second preset surfaces, it is easier to extract and process the fractional differential seismic data volume and the fractional integral data volume in the subsequent process.

[0154] This step can be achieved as follows: based on the linear features of the lake basin bottom shape during the depositional period or the pre-accretion layer features of the pre-accretion reflection structure, determine the first preset surface and the second preset surface, wherein both the first preset surface and the second preset surface are surfaces parallel to the lake basin topography during the depositional period or surfaces intersecting with the pre-accretion layers of all pre-accretion reflection structures.

[0155] Furthermore, based on the linear characteristics of the lake basin bottom shape during the depositional period, a surface parallel to the lake basin bottom shape during the depositional period can be determined; based on the characteristics of the pre-accretionary reflective layers, a surface intersecting with the pre-accretionary reflective layers of all pre-accretionary reflective structures can be determined.

[0156] Step 204: Based on the first preset surface and the second preset surface, extract the fractional differential seismic data volume and the fractional integral seismic data volume respectively to obtain the first layer slice and the second layer slice.

[0157] The first layer slice comprehensively reflects the progradational reflection structure, including both high-frequency data reflecting detailed information about the structure and low-frequency data reflecting its basic orientation and changes. The second layer slice clearly and simply reflects the low-frequency data of the basic orientation and changes of the progradational reflection structure, but does not reflect high-frequency data. Combining the two allows seismic interpreters to intuitively determine the location, basic orientation, and approximate changes of the progradational reflection structure based on the second layer slice, and to further determine the detailed information of the progradational reflection structure from the first layer slice, and to quantitatively determine the progradational reflection structure based on the detailed information.

[0158] In some embodiments, the extraction processing of fractional differential seismic data volumes and fractional integral seismic data volumes can be achieved using the extraction functions of Geoeast, Landmark, or Geoview software.

[0159] Step 205: Based on the first seismic data volume, the second seismic data volume, the first layer slice, and the second layer slice, determine the pre-accretion reflection structure.

[0160] Since both the first and second seismic data volumes can reflect the dominant frequency bands of the progradational reflection structure, and the first and second bedding slices can more intuitively reflect the orientation of the progradational reflection structure, the progradational reflection structure can be determined more accurately based on the first and second seismic data volumes, the first and second bedding slices.

[0161] Therefore, the method for identifying anterior accretion reflection structures provided in this application involves performing fractional-order differentiation and fractional-order integration on the seismic data volume according to a first preset order and a second preset order, respectively, to obtain fractional-order differential seismic data volume and fractional-order integral seismic data volume. Then, by flattening these fractional-order differential and fractional-order integral seismic data volumes, a first seismic data volume and a second seismic data volume can be obtained, thereby determining a first preset surface and a second preset surface. Based on these first and second preset surfaces, the fractional-order differential and fractional-order integral seismic data volumes are further extracted to obtain a first layer slice and a second layer slice. Finally, the anterior accretion reflection structure is determined using the first seismic data volume, the second seismic data volume, the first layer slice, and the second layer slice. Since both the first and second seismic data volumes can reflect the dominant frequency band of the anterior accretion reflection structure, and both the first and second layer slices can more intuitively reflect the orientation of the anterior accretion reflection structure, the method for identifying anterior accretion reflection structures provided in this application can more accurately identify anterior accretion reflection structures.

[0162] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0163] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0164] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for identifying a front-integral reflection structure, characterized in that, The method includes: According to the first preset order, the seismic data volume is subjected to fractional derivative to obtain fractional derivative seismic data volume, wherein the seismic data volume is subjected to fractional derivative according to the following calculation formula; In the formula: It means to ask First-order differential, This refers to the earthquake data volume. This represents the frequency of the seismic data volume. This represents the angular frequency of the seismic data volume. This represents the frequency of the seismic data volume in the frequency domain. t It indicates time. k This represents the rotation parameters; where when k A value of 0 indicates that no phase rotation is performed; when... k A value of 1 indicates that a phase rotation is performed; According to the second preset order, the seismic data volume is integrated by fractional order to obtain the fractional integral seismic data volume, wherein the seismic data volume is integrated by fractional order according to the following calculation formula; ； In the formula: It means to ask Order integral, This refers to the earthquake data volume. This represents the frequency of the seismic data volume. This represents the angular frequency of the seismic data volume. This represents the frequency of the seismic data volume in the frequency domain. t It indicates time. k This represents the rotation parameters; where when k A value of 0 indicates that no phase rotation is performed; when... k A value of 1 indicates that a phase rotation is performed; The fractional differential seismic data volume and the fractional integral seismic data volume are flattened respectively to obtain the first seismic data volume and the second seismic data volume. Based on the first seismic data volume and the second seismic data volume, a first preset surface and a second preset surface are determined respectively; Based on the first preset surface and the second preset profile, the fractional differential seismic data volume is extracted and processed to obtain the first layer slice and the second layer slice. Based on the first seismic data volume, the second seismic data volume, the first layer slice, and the second layer slice, the pre-accretion reflection structure is determined.

2. The method for identifying the front reflection structure according to claim 1, characterized in that, The step of performing fractional-order differentiation on the seismic data volume according to a first preset order to obtain a fractional-order differential seismic data volume includes: The seismic data volume is subjected to Fourier transform processing to obtain the seismic data volume in the frequency domain; Based on the first preset order, the frequency domain seismic data volume is subjected to fractional derivative to obtain the fractional derivative seismic data volume.

3. The method for identifying pre-accretionary reflection structures according to claim 1, wherein the first seismic data volume possesses linear features of a lake basin bottom shape during the depositional period and pre-accretionary layer features of a pre-accretionary reflection structure, characterized in that, The step of determining a first preset surface and a second preset surface based on the first seismic data volume and the second seismic data volume respectively includes: Based on the linear features of the lake basin bottom shape during the depositional period or the pre-accretion layer features of the pre-accretion reflection structure, the first preset surface is determined, wherein the first preset surface is a surface parallel to the lake basin bottom shape during the depositional period or a surface that intersects with the pre-accretion layers of all pre-accretion reflection structures.

4. The method for identifying the front reflection structure according to claim 3, characterized in that, The step of extracting and processing the fractional-order differential seismic data volume based on the first preset surface and the second preset profile to obtain a first and a second bedding slice includes: Based on the plane parallel to the lake basin bottom shape during the deposition period or the plane intersecting with the pre-accretion layers of all pre-accretion reflection structures, the fractional-order differential seismic data volume is extracted and processed to obtain the first layer slice.

5. The method for identifying the front reflection structure according to claim 1, characterized in that, The determination of the pre-accretion reflection structure based on the first seismic data volume, the second seismic data volume, the first along-layer slice, and the second along-layer slice includes: Based on the first seismic data volume, the dominant frequency band of the pre-accretionary reflection structure is determined; Based on the first slice along the layer, the orientation of the pre-integral reflection structure is determined; The front accretion reflection structure is determined based on its dominant frequency band and orientation.

6. The method for identifying the front reflection structure according to claim 1, characterized in that, After extracting and processing the fractional-order differential seismic data volume according to the first preset surface and the second preset profile to obtain the first and second bedding slices, the method further includes: Based on well logging data, drilling data, the first seismic data volume, and the first stratigraphic slice, the progradation dip angle, paleowater depth, progradation stage, stratigraphic accretion rate, stratigraphic progradation rate, and main depositional direction are determined.

7. The method for identifying the front reflection structure according to claim 6, characterized in that, The determination of progradation dip angle, paleowater depth, progradation stage, stratigraphic accretion rate, progradation rate, and main depositional direction based on well logging data, drilling data, the first seismic data volume, and the first stratigraphic slice includes: Based on the well logging data, the drilling data, and the first seismic data volume, determine the progradation dip angle and the paleowater depth; Based on the well logging data, the drilling data, the first seismic data volume, and the first stratigraphic slice, the development stage, the stratigraphic accretion rate, the stratigraphic progradation rate, and the main depositional direction are determined.

8. The method for identifying the front-integral reflection structure according to claim 7, characterized in that, The step of determining the progradation dip angle and the paleowater depth based on the well logging data, the drilling data, and the first seismic data volume includes: Based on the first seismic data volume, the forward inclination angle is calculated; Determine the formation compaction coefficient based on drilling and logging data; The depth of the paleowater body is calculated based on the compaction coefficient and the first seismic data volume.

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