Automatic horizon tracking method and apparatus and readable storage medium

Abstract

An automatic horizon tracking method, comprising: acquiring seismic data and depths of the same horizon in different input wells; determining a stratigraphic profile dip angle of each seismic trace on the basis of the seismic data; determining an initial horizon depth of each seismic trace on the basis of the depths of the same horizon in different input wells; on the basis of the stratigraphic profile dip angle of each seismic trace and the initial horizon depth of each seismic trace, constructing a target function by taking the depths of the same horizon in different input wells as constraint conditions; and carrying out iterative calculation on the target function, iteratively updating the horizon depth of each seismic trace until the target function converges, and outputting the updated horizon depth of each seismic trace. Both the continuity of seismic horizons in the range of the whole work area and the consistency with well calibration horizon information can be achieved, the tracking result is stable, and fitness to the real horizon trend is achieved. Also provided are an automatic horizon tracking apparatus and a readable storage medium.

Description

Automatic layer tracking method, device and readable storage medium Technical Field

[0001] The present invention relates to the technical field of petroleum geophysical exploration, and in particular to a layer automatic tracking method, a layer automatic tracking device and a readable storage medium. Background Art

[0002] Identifying and tracking horizons in seismic data is a crucial step in seismic exploration. Structural interpretation is fundamental to seismic interpretation and also provides a crucial data basis for seismic data processing. Take, for example, depth-domain modeling of seismic data. Depth-domain modeling often employs a layer-by-layer approach, modeling from shallow to deep layers. Horizon interpretation is the first and most important step in depth-domain modeling. High-precision horizon interpretation significantly improves the accuracy and efficiency of velocity modeling.

[0003] Currently, two common horizon interpretation methods are manual picking and automatic tracking. Manual picking involves manually analyzing the continuity of events along the seismic profile and then manually picking horizons along the peaks (or troughs, or zero-amplitude lines) of the seismic wavelets. Its advantages are that the interpretation results meet user expectations and are relatively intuitive. However, to achieve high-precision picking results, the user must perform relatively precise picking, which results in a significant workload for manual interpretation and horizon adjustment. Furthermore, the interpretation results rely heavily on the interpreter's geological experience. As seismic exploration areas expand, the volume of seismic data also increases. Relying solely on manual picking is not only labor-intensive but also inefficient in producing high-precision interpretation results. Automatic tracking interpretation involves tracking horizons based on the similarity of adjacent seismic traces after a seed point is given. Specifically, a seed point is manually assigned. At the sampling location of the seed point, the horizon waveform is extracted within a specified time window. Starting from the seed point, a search is conducted outward toward adjacent seismic traces for a waveform segment similar to the seed point waveform. The midpoint of this waveform segment is the depth of the horizon to be tracked in the adjacent traces. This point can be used as a new seed point to search for the waveform of the next adjacent channel. This method is convenient and easy to use, but the tracking results are easily affected by the seed point and the signal-to-noise ratio of the data. Tracking results using different seed points at the same location can vary. Cross-correlation and false faults can occur far from the initial artificial seed point, resulting in an incomplete layer plane. The tracking range is uncontrolled, and manual correction is impossible during the tracking process.

[0004] Although a grid-based horizon tracking method has been proposed, it involves gridding seismic data and automatically tracking within the grid. The gridded tracking results are then quality-controlled and modified, and reverse grid-corrected tracking is performed before continuing forward. However, this tracking method is not only complex but also fails to ensure the continuity of seismic horizons across the entire work area and their consistency with well calibration horizon information. Furthermore, the tracking results are often unstable and often lack accuracy that matches the true horizon direction.

[0005] Summary of the Invention

[0006] The purpose of the embodiments of the present invention is to provide a method, device and readable storage medium for automatic layer tracking, so as to at least solve the problem that the above-mentioned existing layer tracking method is not only complicated in operation steps, but also cannot take into account the continuity of the seismic layer in the entire work area and the consistency with the well calibration layer information, and the tracking results are often not stable enough, and the overall accuracy problem of not being consistent with the actual layer trend often occurs.

[0007] In order to achieve the above object, the present invention provides a first aspect of a layer automatic tracking method, the method comprising:

[0008] Obtain seismic data and the depth of the same layer in different input wells;

[0009] Determining the dip angle of the stratigraphic section of each seismic trace based on the seismic data;

[0010] Determine the initial depth of each seismic trace based on the depth of the same horizon in different input wells;

[0011] Based on the dip angle of the stratigraphic section of each seismic trace and the initial layer depth of each seismic trace, the objective function is constructed with the depth of the same layer in different input wells as the constraint condition;

[0012] The objective function is iteratively calculated, and the layer depth of each seismic trace is iteratively updated until the objective function converges, and the updated layer depth of each seismic trace is output.

[0013] Optionally, determining the formation dip based on the seismic data includes:

[0014] Based on the seismic data, obtaining seismic profile data;

[0015] The seismic profile data is scanned for seismic dip angles to determine the stratum profile dip angle of each seismic trace in the seismic profile.

[0016] Optionally, the method further includes:

[0017] The seismic profile data is subjected to noise removal and amplitude equalization processing.

[0018] Optionally, the input well includes a first input well and a second input well;

[0019] Based on the depth of the same layer of the input well, determine the initial layer depth of each seismic trace, including:

[0020] Among them, Z i is the initial layer depth of the i-th seismic trace; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well; N is the number of seismic traces between the first input well and the second input well.

[0021] Optionally, the objective function is expressed as: F = F1 + F3

[0022] Where F is the objective function; F1 is the formation dip information matching function; N is the number of seismic traces between the first input well and the second input well; ω1 is the weight factor of the formation dip information matching function; Z i is the initial layer depth of the i-th seismic trace; Z i-1 is the initial layer depth of the i-1th seismic trace; Δx is the lateral distance between the i-1th seismic trace and the i-1th seismic trace; d i is the dip angle of the stratigraphic profile of the i-th seismic trace in the seismic profile; F3 is the damping function; ω3 is the weight factor of the damping function; Z i+1 is the initial horizon depth of the i+1th seismic trace.

[0023] Optionally, the constraint condition of the objective function is: Z0=Z A Z N-1 =Z B

[0024] Among them, Z0 is the initial layer depth of the 0th seismic trace; Z N-1 is the initial layer depth of the N-1th seismic trace; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well.

[0025] Optionally, iteratively calculating the objective function and iteratively updating the layer depth of each seismic trace until the objective function converges, and outputting the updated layer depth of each seismic trace, including:

[0026] The objective function is solved by using the least square method, and the layer depth of each seismic trace is updated in each iteration;

[0027] When the objective function converges, the layer depth of each seismic trace updated in this iteration is output.

[0028] Optionally, update the horizon depth of each seismic trace using the following formula:

[0029] in, is the horizon depth of the i-th seismic trace after the m+1-th iteration; is the horizon depth of the i-th seismic trace after the m-th iteration; is the layer depth correction value after the mth iteration; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well.

[0030] A second aspect of the present invention provides a layer automatic tracking device, the device comprising:

[0031] Data acquisition module, used to obtain seismic data and the depth of the same layer in different input wells;

[0032] a stratigraphic section dip determination module, configured to determine the stratigraphic section dip of each seismic trace based on the seismic data;

[0033] An initial horizon depth determination module is used to determine the initial horizon depth of each seismic trace based on the depths of the same horizon in different input wells;

[0034] An objective function construction module is used to construct an objective function based on the stratigraphic profile dip of each seismic trace and the initial layer depth of each seismic trace, with the depth of the same layer in different input wells as a constraint condition;

[0035] The layer depth output module is used to iteratively calculate the objective function and iteratively update the layer depth of each seismic trace until the objective function converges, and output the updated layer depth of each seismic trace.

[0036] On the other hand, the present invention further provides a readable storage medium having stored thereon instructions for causing a machine to execute the above-mentioned automatic layer tracking method.

[0037] This technical solution has simple operating steps and can take into account the continuity of seismic layers throughout the entire work area and the consistency with the well calibration layer information. The tracking results are stable and fit the actual layer trend, achieving efficient and high-precision automatic layer tracking.

[0038] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0040] FIG1 is a flow chart of a method for automatically tracking a layer provided by the present invention;

[0041] FIG2 is a schematic diagram of a seismic profile provided by the present invention;

[0042] FIG3 is a schematic diagram of the dip angle of the stratum section provided by the present invention;

[0043] FIG4 is a schematic diagram of the initial layer depth provided by the present invention;

[0044] FIG5 is a schematic diagram of the updated layer depth provided by the present invention;

[0045] FIG6 is a schematic diagram of the convergence of the objective function provided by the present invention;

[0046] FIG7 is a schematic structural diagram of the automatic layer tracking device provided by the present invention.

[0047] Explanation of reference numerals 10 - data acquisition module; 20 - stratigraphic profile dip determination module; 30 - initial layer depth determination module; 40 - objective function construction module; 50 - layer depth output module. DETAILED DESCRIPTION

[0048] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0049] Figure 1 is a flow chart of the automatic layer tracking method provided by the present invention; Figure 2 is a schematic diagram of the seismic profile provided by the present invention; Figure 3 is a schematic diagram of the inclination of the stratigraphic profile provided by the present invention; Figure 4 is a schematic diagram of the initial layer depth provided by the present invention; Figure 5 is a schematic diagram of the updated layer depth provided by the present invention; Figure 6 is a schematic diagram of the convergence of the objective function provided by the present invention; and Figure 7 is a structural schematic diagram of the automatic layer tracking device provided by the present invention.

[0050] As shown in FIG1 , an embodiment of the present invention provides a method for automatic layer tracking, the method comprising:

[0051] Step 1: Obtain seismic data and the depth of the same layer in different input wells;

[0052] In this example, seismic waves are excited to the surface and recorded, and the seismic data collected in the field are processed according to a conventional seismic data processing procedure to obtain seismic data.

[0053] Step 2: determining the dip angle of the stratigraphic profile of each seismic trace based on the seismic data;

[0054] Specifically, in this embodiment, determining the formation dip based on the seismic data includes:

[0055] Step 201: obtaining seismic profile data based on the seismic data;

[0056] Step 202: Scan the seismic profile data for seismic dip angles to determine the dip angle of each seismic trace in the seismic profile and record it as d i .

[0057] In another embodiment, after obtaining the seismic profile data in step 201, the method further includes:

[0058] The seismic profile data is subjected to noise removal and amplitude equalization processing.

[0059] By adopting the above method, the interference of noise signals can be eliminated, the accuracy of data can be guaranteed, and the stratigraphic profile dip of each seismic trace obtained after seismic dip scanning can be more accurate, thereby improving the accuracy of layer tracking.

[0060] Step 3: Determine the initial depth of each seismic trace based on the depths of the same layer in different input wells;

[0061] In this embodiment, the depth information of the same layer at different input well locations is obtained based on the calibrated layer information of the input well. Taking two wells (the first input well and the second input well) as an example, assuming that the depth of a certain layer at the first input well is Z A , the depths at the first input well are Z B , based on Z A and Z B The initial value of the seismic horizon depth is constructed using linear interpolation. Specifically, the following calculation formula is used to calculate the initial horizon depth of each seismic trace:

[0062] Among them, Z i is the initial layer depth of the i-th seismic trace; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well; N is the number of seismic traces between the first input well and the second input well; i is the index of the seismic trace.

[0063] Step 4: Based on the dip angle of the stratigraphic profile of each seismic trace and the initial layer depth of each seismic trace, the objective function is constructed with the depth of the same layer in different input wells as a constraint condition;

[0064] In this embodiment, the depth of the same layer in different input wells is the well information matching information, and an objective function based on the well information matching information and least squares optimization can be constructed. The expression of the objective function is: F = F1 + F3

[0065] Where F is the objective function; F1 is the formation dip information matching function; N is the number of seismic traces between the first input well and the second input well; ω1 is the weight factor of the formation dip information matching function; Z i is the initial layer depth of the i-th seismic trace; Z i-1 is the initial layer depth of the i-1th seismic trace; Δx is the lateral distance between the i-1th seismic trace and the i-1th seismic trace; d i is the dip angle of the stratigraphic profile of the i-th seismic trace in the seismic profile; F3 is the damping function; ω3 is the weight factor of the damping function; Z i+1 is the initial horizon depth of the i+1th seismic trace.

[0066] More specifically, It can be expressed as Its meaning is based on the layer depth Z of the i-th seismic trace i and the horizon depth Z of the i-1th seismic trace i-1 The calculated dip angle value of the i-th channel is iteratively compared with the dip angle of the stratum section of the i-th seismic channel in the seismic section; similarly, It can be expressed as Its meaning is based on the layer depth Z of the i+1th seismic trace i+1 and the horizon depth Z of the i-th seismic trace i The calculated dip angle value of the i+1th trace is iteratively compared with the dip angle of the stratigraphic profile of the i-th seismic trace in the seismic profile.

[0067] The constraint condition of the objective function is: Z0=Z A Z N-1 =Z B

[0068] Among them, Z0 is the initial layer depth of the 0th seismic trace; Z N-1 is the initial layer depth of the N-1th seismic trace; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well.

[0069] In this embodiment, the set constraint conditions can ensure that the depth of the same layer at the well position of the first input well and the depth at the well position of the second input well remain unchanged after the update.

[0070] Step 5: Iteratively calculate the objective function and iteratively update the layer depth of each seismic trace until the objective function converges, and then output the updated layer depth of each seismic trace.

[0071] Specifically, the method includes: solving the objective function by using the least square method, and updating the layer depth of each seismic trace in each iteration;

[0072] When the objective function converges, the layer depth of each seismic trace updated during this iteration is output, and the updated layer depth of each seismic trace is obtained. Then, based on the layer depth of each seismic trace, the layer in the entire stratum can be obtained.

[0073] In this embodiment, the least squares iterative optimization of the constructed initial layer depth is performed using the objective function F. The first-order derivative of the objective function F with respect to the layer depth is calculated to construct the equation:

[0074] Among them, Z i is the initial layer depth of the i-th seismic trace; i is 0, 1, ..., N-1;

[0075] The equation constructed by the first-order derivative is a nonlinear equation and can be solved by the Newton iteration method. First, use the initial value of the layer depth obtained above as Then, in each iteration m, the layer depth correction amount Accumulated to the current layer depth Get the updated layer depth:

[0076] in, is the horizon depth of the i-th seismic trace after the m+1-th iteration; is the horizon depth of the i-th seismic trace after the m-th iteration; is the layer depth correction value after the mth iteration; Z A is the depth of the layer at the well location of the first input well; Z B is the depth of the layer at the well location of the second input well.

[0077] Specifically, This can be obtained by solving the following five diagonal equations:

[0078] in, is the second-order derivative of the objective function F with respect to the layer depth, and j is the index of the seismic trace. Moreover, the value of j is: max(0,i-2)≤j≤min(N-1,i+2), so, through Δz j able to obtain value.

[0079] More specifically, in this embodiment, in order to reflect the technical advantages of the present invention, complex seismic data was used to conduct an effect test. Figure 2 shows a seismic profile after noise removal and amplitude equalization processing. The horizontal coordinate axis is the number of the seismic trace, and the vertical coordinate axis is the imaging depth. It can be seen that the data structure is complex and has layers with steep dips, which is very challenging. Figure 3 is the stratigraphic dip information obtained by scanning the seismic profile shown in Figure 2, that is, the stratigraphic profile dip of each seismic trace, where the horizontal and vertical coordinate axes have the same meanings as Figure 2, and the figure shows the tangent value of the dip of the seismic profile. Figure 4 is the initial value of the seismic layer depth constructed after the layer depth of the two wells is given. It is obtained by linear interpolation based on the layer depth of the two wells, and the horizontal and vertical coordinate axes have the same meanings as Figure 2. The layer depth tracked using the automatic tracking algorithm of the present invention is shown as the black solid line in Figure 5. It can be seen that the layer tracking accuracy is very high. The black solid line almost completely coincides with the wave crest of the seismic phase axis. Even in steep structures, the tracked horizons closely match the events, verifying the algorithm's effectiveness and high accuracy. Figure 6 shows the convergence of the least squares iteration objective function. The horizontal axis represents the number of iterations, and the vertical axis represents the objective function value. As can be seen, after seven iterations, the objective function value met the requirements. The run time was approximately 0.5 seconds, meeting the requirements for real-time interactive horizon picking. This method achieves efficient and high-precision automatic horizon tracking, overcoming the challenges of poor stability and low accuracy associated with traditional methods.

[0080] As shown in FIG7 , an embodiment of the present invention further provides a layer automatic tracking device, the device comprising:

[0081] The data acquisition module 10 is used to obtain seismic data and the depth of the same layer in different input wells;

[0082] a stratigraphic section dip determination module 20 for determining the stratigraphic section dip of each seismic trace based on the seismic data;

[0083] An initial horizon depth determination module 30 is used to determine the initial horizon depth of each seismic trace based on the depths of the same horizon in different input wells;

[0084] An objective function construction module 40 is used to construct an objective function based on the stratigraphic profile dip of each seismic trace and the initial layer depth of each seismic trace, with the depth of the same layer in different input wells as a constraint condition;

[0085] The horizon depth output module 50 is used to iteratively calculate the objective function and iteratively update the horizon depth of each seismic trace until the objective function converges, and then output the updated horizon depth of each seismic trace.

[0086] An embodiment of the present invention further provides a readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the above-mentioned automatic layer tracking method.

[0087] Those skilled in the art will appreciate that all or part of the steps in the methods of the aforementioned embodiments can be accomplished by instructing the relevant hardware through a program, which is stored in a storage medium and includes a number of instructions for causing a single-chip microcomputer, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0088] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other and are not used to limit the scope of protection of the present invention.

[0089] The above describes in detail the optional embodiments of the present invention in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, a variety of simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the scope of protection of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the embodiments of the present invention will no longer describe the various possible combinations separately.

[0090] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A layer automatic tracking method, characterized in that: The method comprises: Obtain seismic data and the depth of the same layer in different input wells; Based on the seismic data, determining the inclination angle of the stratigraphic section of each seismic trace; Determine the initial depth of each seismic trace based on the depth of the same layer in different input wells; Based on the dip angle of the stratigraphic profile of each seismic trace and the initial layer depth of each seismic trace, the objective function is constructed with the depth of the same layer in different input wells as the constraint condition; The objective function is iteratively calculated, and the layer depth of each seismic trace is iteratively updated until the objective function converges, and the updated layer depth of each seismic trace is output.

2. The automatic layer tracking method according to claim 1, characterized in that: Determining the formation dip based on the seismic data includes: Based on the seismic data, obtaining seismic profile data; The seismic profile data is scanned for seismic dip angles to determine the dip angle of the stratum profile of each seismic trace in the seismic profile.

3. The automatic layer tracking method according to claim 2, characterized in that: The method further comprises: The seismic profile data is subjected to noise removal and amplitude equalization processing.

4. The automatic layer tracking method according to claim 1, characterized in that: The input wells include a first input well and a second input well; Based on the depth of the same layer of the input well, determine the initial layer depth of each seismic trace, including: Among them, Z i is the initial layer depth of the ith seismic trace; Z A is the depth of the layer at the well position of the first input well; Z B is the depth of the layer at the well position of the second input well; N is the number of seismic traces between the first input well and the second input well.

5. The automatic layer tracking method according to claim 4, characterized in that: The objective function is expressed as: F = F1 + F3 Where F is the objective function; F1 is the formation dip information matching function; N is the number of seismic traces between the first input well and the second input well; ω1 is the weight factor of the formation dip information matching function; Z i is the initial layer depth of the ith seismic trace; Z i-1 is the initial layer depth of the i-1th seismic trace; Δx is the lateral distance between the i-1th seismic trace and the i-1th seismic trace; d i is the inclination angle of the stratigraphic profile of the i-th seismic trace in the seismic profile; F3 is the damping function; ω3 is the weight factor of the damping function; Z i+1 is the initial layer depth of the i+1th seismic trace.

6. The automatic layer tracking method according to claim 4, characterized in that: The constraint condition of the objective function is: Z0=Z A Z N-1 =Z B Where Z0 is the initial layer depth of the 0th seismic trace; Z N-1 is the initial layer depth of the N-1th seismic trace; Z A is the depth of the layer at the well position of the first input well; Z B is the depth of the layer at the well location of the second input well.

7. The automatic layer tracking method according to claim 1, characterized in that: Iteratively calculating the objective function and iteratively updating the layer depth of each seismic trace until the objective function converges, and outputting the updated layer depth of each seismic trace, including: The objective function is solved by using the least square method, and the layer depth of each seismic trace is updated in each iteration; When the objective function converges, the layer depth of each seismic trace updated in this iteration is output.

8. The automatic layer tracking method according to claim 1, characterized in that: The layer depth of each seismic trace is updated using the following formula: in, is the layer depth of the ith seismic trace after the m+1th iteration; is the layer depth of the ith seismic trace after the mth iteration; is the layer depth correction after the mth iteration; Z A is the depth of the layer at the well position of the first input well; Z B is the depth of the layer at the well location of the second input well.

9. A layer automatic tracking device, characterized in that: The device comprises: Data acquisition module, used to obtain seismic data and the depth of the same layer in different input wells; A stratigraphic section dip angle determination module, used to determine the stratigraphic section dip angle of each seismic trace based on the seismic data; An initial layer depth determination module is used to determine the initial layer depth of each seismic trace based on the depth of the same layer in different input wells; An objective function construction module is used to construct an objective function based on the stratigraphic profile dip angle of each seismic trace and the initial layer depth of each seismic trace, taking the depth of the same layer in different input wells as a constraint condition; The layer depth output module is used to iteratively calculate the objective function and iteratively update the layer depth of each seismic trace until the objective function converges, and then output the updated layer depth of each seismic trace.

10. A readable storage medium having instructions stored thereon, wherein the instructions are used to enable a machine to execute the automatic layer tracking method described in any one of claims 1 to 8.

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