Method, device, equipment and storage medium for determining seismic depth domain velocity model

Abstract

The present application provides a method, device, equipment and storage medium for determining a seismic depth domain velocity model, including: obtaining first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point; determining a velocity mutation layer segment based on the first well logging velocity data; determining third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first well logging velocity data and the second seismic depth domain velocity data; and determining a seismic depth domain velocity model based on the third seismic depth domain velocity data and the first seismic depth domain velocity data.

Description

Technical Field

[0001] The present application relates to the technical field of seismic data testing, and in particular to a method, device, equipment and storage medium for determining a seismic depth domain velocity model. Background Art

[0002] The seismic wave velocity field is the link between seismic and geological data. An accurate velocity field is the guarantee of the accuracy of pre-stack depth migration imaging. Establishing an accurate velocity field is an important research topic in geophysics, which directly affects the benefits and results of oil and gas exploration and development. Especially in areas with complex structures and large lateral velocity changes, the time domain velocity cannot meet the imaging requirements, and depth domain velocity modeling is required. At present, the conventional seismic depth domain velocity modeling methods can be divided into two categories: tomographic velocity analysis and travel time inversion. Among them, the former tomographic velocity analysis method based on the residual velocity analysis of the migration imaging gather is the most widely used method in the industry. With the stacking of the latter, the corresponding confocal velocity analysis method, angular gather velocity analysis method and current research hotspots, full waveform inversion, etc., are still not widely used in actual production due to the limitations of computational cost and data applicability. Therefore, the improvement of tomographic technology is more timely for actual production.

[0003] Conventional tomography methods use the residual time difference (RMO) on the imaging gather to reflect the disturbance difference corresponding to the residual velocity. Through migration and velocity iteration, the similarity between the depth domain velocity model and the actual underground true velocity is improved based on the improvement of the flattening degree of the gather after iteration. For the depth domain velocity model based on the tomography method, the establishment of the initial velocity model is particularly important. In general, the time-depth conversion of the time domain layer velocity model obtains the conventional depth domain initial velocity model. However, since the time domain velocity model is generally very flat and cannot adapt to the sudden change of the horizontal and vertical velocity, especially the lateral velocity, and the tomography method requires the initial depth domain velocity model to be smooth (otherwise the later velocity iteration process of the tomography method will fall into the local extreme value), the initial depth model in general is quite different from the actual formation true velocity, and basically does not have the characteristics of velocity mutation. In the Ordovician system, which is the main target layer, there are velocity mutations of more than 500m / s or even nearly 1000m / s above and below the T74 layer of its top interface due to changes in formation lithology and pressure. However, due to the limitation of the tomographic inversion algorithm, it is impossible to update the velocity through the iteration of the seismic data itself to reflect the velocity mutation above and below this layer. The limitations of the tomographic iteration theory are as follows: The basic principle of the traditional seismic velocity modeling method based on tomography is to input the residual time difference of the entire seismic track set as a constraint, and adjust the velocity model through the mathematical inversion optimization process to minimize the residual velocity, and then find the best velocity model that matches the actual velocity of the actual underground medium in a certain mathematical sense. It is well known that, similar to most inversion problems, seismic tomography inversion is usually underdetermined and ill-conditioned, and this ill-conditioned problem is particularly serious in the case of inverting anisotropic media. The larger the anisotropy of the medium, the larger the mutation gradient in each direction, and the more serious the inversion ill-conditioned problem, that is, the lower the accuracy of velocity iteration. In addition, due to the limitations of seismic data acquisition technology, environment, and cost, actual seismic data are often only surface data within a limited spatial acquisition range, which also causes a certain uncertainty between different model parameters of tomographic inversion, and between model parameters and stratum depth, that is, there are multiple model parameter combinations that can make different seismic velocities have equivalent imaging results within different error ranges with the actual underground true velocity. Due to these theoretical and practical limitations, it is often found in actual seismic data processing that although tomographic inversion does reduce the residual time difference or residual velocity of the gather, the velocity model obtained by inversion is inconsistent with other geological and geophysical data, such as acoustic logging velocity curves, and sometimes there is a big gap. The logging velocity is obtained by measuring the actual underground medium, and the seismic velocity is completely based on the original seismic data through various mathematical approximation theories, making the existing seismic velocity model inaccurate. Summary of the invention

[0004] In response to the above problems, the present application provides a method, device, equipment and storage medium for determining a seismic depth domain velocity model.

[0005] The present application provides a method for determining a seismic depth domain velocity model, comprising:

[0006] Acquire first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point;

[0007] Determine a velocity mutation interval based on the first logging velocity data;

[0008] Determine third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first well logging velocity data and the second seismic depth domain velocity data;

[0009] A seismic depth-domain velocity model is determined based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0010] In some embodiments, determining the third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first well logging velocity data and the second seismic depth-domain velocity data comprises:

[0011] Determine the second well logging velocity data corresponding to the velocity mutation layer section and the third well logging velocity data corresponding to the non-velocity mutation layer section in the first well logging velocity data;

[0012] Determine fourth seismic depth-domain velocity data corresponding to the non-velocity mutation segment in the second seismic depth-domain velocity data;

[0013] Based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data, the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation section is determined.

[0014] In some embodiments, determining the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation segment based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data comprises:

[0015] Determine fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data;

[0016] Determine sixth seismic depth domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth domain velocity data;

[0017] The third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment is determined based on the fifth seismic depth-domain velocity data and the sixth seismic depth-domain velocity data.

[0018] In some embodiments, determining the sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth-domain velocity data includes:

[0019] Interpolation processing is performed based on the fifth seismic depth-domain velocity data to determine sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point.

[0020] In some embodiments, determining sixth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data comprises:

[0021] Determine the depth position of a in the velocity mutation layer;

[0022] Determine a ratio of a fourth seismic depth domain velocity corresponding to the depth position a to a third well logging velocity data corresponding to the depth position a;

[0023] Determine a product value of the second logging velocity data corresponding to the depth position a and the ratio;

[0024] The product value is determined as the logging velocity corresponding to the depth position a.

[0025] In some embodiments, determining a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data comprises:

[0026] Determine seventh seismic depth-domain velocity data corresponding to each depth point in the first seismic depth-domain velocity data, wherein the seventh seismic depth-domain velocity data is the same as each position point corresponding to the third seismic depth-domain velocity data;

[0027] Replacing the seventh seismic depth-domain seismic velocity data with the third seismic depth-domain velocity data to obtain target seismic velocity data;

[0028] A seismic velocity model is determined based on the target seismic velocity data.

[0029] In some embodiments, determining the velocity mutation section based on the first logging velocity data comprises:

[0030] Determine a logging velocity smooth curve based on the first logging velocity data;

[0031] Determining the curvature change of each section based on the logging velocity smooth curve;

[0032] In the case where there is a curvature change greater than a preset threshold, the depth segment corresponding to the logging velocity smooth curve segment corresponding to the curvature change greater than the preset threshold is determined as a velocity mutation segment.

[0033] The embodiment of the present application provides a device for determining a seismic depth domain velocity model, comprising:

[0034] An acquisition module, used for acquiring first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point;

[0035] A first determination module, configured to determine a velocity mutation layer interval based on the first logging velocity data;

[0036] A second determination module is used to determine third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second seismic depth domain velocity data;

[0037] The third determination module is used to determine a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0038] An embodiment of the present application provides a device for determining a seismic depth domain velocity model, comprising a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, any one of the above-mentioned methods for determining a seismic depth domain velocity model is executed.

[0039] An embodiment of the present application provides a storage medium, and a computer program stored in the storage medium can be executed by one or more processors and can be used to implement any of the above-mentioned methods for determining a seismic depth domain velocity model.

[0040] The present application provides a method, device, equipment and storage medium for determining a seismic depth domain velocity model. The method determines a velocity mutation layer segment through first logging velocity data. After the velocity mutation layer segment is determined, the first logging velocity data is used to constrain the second address depth domain velocity data at the well point to determine the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment, and the seismic depth domain velocity model is determined based on the third seismic depth domain velocity data. Due to the constraint by the first logging velocity, the velocity near the velocity mutation layer is closer to the actual underground medium velocity, and the velocity model is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Hereinafter, the present application will be described in more detail based on embodiments and with reference to the accompanying drawings.

[0042] Figure 1 A schematic diagram of an implementation flow of a method for determining a seismic depth domain velocity model provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of an implementation flow of another method for determining a seismic depth domain velocity model provided in an embodiment of the present application;

[0044] Figure 3 A schematic diagram of an implementation flow of another method for determining a seismic depth domain velocity model provided in an embodiment of the present application;

[0045] Figure 4 A schematic diagram of an implementation flow of a method for determining a seismic depth domain velocity model provided in an embodiment of the present application;

[0046] Figure 5 A schematic diagram of a comparison between an unoptimized seismic velocity and a well velocity provided in an embodiment of the present application;

[0047] Figure 6 A schematic diagram of imaging based on non-optimized seismic velocity provided in an embodiment of the present application;

[0048] Figure 7 A comparison chart of imaging effects before and after optimization provided in the embodiment of the present application;

[0049] Figure 8 A schematic diagram of the structure of a device for determining a seismic depth-domain velocity model provided in an embodiment of the present application;

[0050] Fig. 9 A schematic diagram of the composition structure of a device for determining a seismic depth domain velocity model provided in an embodiment of the present application.

[0051] In the drawings, the same reference numerals are used for the same components, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0053] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0054] If similar descriptions of "first\second\third" appear in the application documents, the following instructions will be added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0056] Based on the problems existing in the related art, an embodiment of the present application provides a method for determining a seismic depth domain velocity model, and the method is applied to a device for determining a seismic depth domain velocity model. The function implemented by the method for determining a seismic depth domain velocity model provided in the embodiment of the present application can be implemented by calling a program code by a processor of an electronic device, wherein the program code can be stored in a computer storage medium.

[0057] Embodiment 1

[0058] The present application provides a method for determining a seismic depth domain velocity model. Figure 1 A schematic diagram of the implementation flow of a method for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, including:

[0059] Step S101, obtaining first seismic depth domain velocity data and first well logging velocity data of a well point.

[0060] In an embodiment of the present application, the first seismic depth domain velocity data includes: the second seismic depth domain velocity data at the well point, and also includes seismic depth domain velocity data at non-well points. The determination device of the seismic depth domain velocity model can obtain the first seismic depth domain velocity data and the first well logging velocity data at the well point from the server through the network. In some embodiments, the determination device of the seismic depth domain velocity model can be connected to each test device, and directly obtain the first seismic depth domain velocity data and the first well logging velocity data of the well point from each test device. In an embodiment of the present application, the resolution of the first seismic depth domain velocity data is less than the resolution of the first well logging velocity data. The first well logging velocity data usually measures the velocity of each depth point in cm, while the first seismic depth domain velocity data usually measures the velocity of the depth point in meters. For example, the first well logging velocity data has been measured in units of 12 cm, and the first seismic depth domain velocity data has been measured in units of 50 meters. In an embodiment of the present application, the well point may include multiple. Each well point corresponds to the first well logging velocity data.

[0061] Step S102: determining a velocity mutation interval based on the first logging velocity data.

[0062] In an embodiment of the present application, smoothing processing can be performed based on the first logging velocity data to obtain a logging velocity smooth curve; the curvature change of each segment is determined based on the logging velocity smooth curve; when there is a curvature change greater than a preset threshold, the depth layer segment corresponding to the logging velocity smooth curve segment corresponding to the curvature change greater than the preset threshold is determined as a velocity mutation layer segment.

[0063] Step S103: determining third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second seismic depth-domain velocity data.

[0064] In the embodiment of the present application, each depth point in the mutation layer segment may include each depth point at the well point and the depth point at the non-well point. In the embodiment of the present application, determining the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second seismic depth domain velocity data may be achieved by the following steps: determining the second logging velocity data corresponding to the velocity mutation layer segment and the third logging velocity data corresponding to the non-velocity mutation layer segment in the first logging velocity data; determining the fourth seismic depth domain velocity data corresponding to the non-velocity mutation segment in the second seismic depth domain velocity data; determining the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation segment based on the second logging velocity data, the third logging velocity data and the fourth seismic depth domain velocity data. In an embodiment of the present application, determining the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation segment based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data can be achieved by the following steps: determining the fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation segment at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; determining the sixth seismic depth domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth domain velocity data; determining the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the fifth seismic depth domain velocity data and the sixth seismic depth domain velocity data.

[0065] In an embodiment of the present application, determining the fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation segment at the well point based on the second logging velocity data, the third logging velocity data and the fourth seismic depth domain velocity data can be achieved by the following steps: determining a depth position a in the velocity mutation layer segment; determining the ratio of the fourth seismic depth domain velocity corresponding to the a depth position to the third logging velocity data corresponding to the a depth position; determining the product value of the second logging velocity data corresponding to the a depth position and the ratio; and determining the product value as the logging velocity corresponding to the a depth position.

[0066] Step S104: determining a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0067] In an embodiment of the present application, determining a seismic depth domain velocity model based on the third seismic depth domain velocity data and the first seismic depth domain velocity data can be achieved by the following steps: determining seventh seismic depth domain velocity data corresponding to each depth point in the first seismic depth domain velocity data, wherein the seventh seismic depth domain velocity data is the same as each position point corresponding to the third seismic depth domain velocity data; replacing the seventh seismic depth domain seismic velocity data with the third seismic depth domain velocity data to obtain target seismic velocity data; and determining a seismic velocity model based on the target seismic velocity data.

[0068] The present application provides a method for determining a seismic depth domain velocity model. The method determines a velocity mutation layer segment by using first logging velocity data. After the velocity mutation layer segment is determined, the first logging velocity data is used to constrain the second address depth domain velocity data at the well point, and the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment is determined. The seismic depth domain velocity model is determined based on the third seismic depth domain velocity data. Due to the constraint by the first logging velocity, the velocity near the velocity mutation layer is closer to the actual underground medium velocity, and the seismic velocity model is more accurate.

[0069] Embodiment 2

[0070] Based on the above-mentioned embodiments, the present application further provides a method for determining a seismic depth domain velocity model. Figure 2 A schematic diagram of the implementation flow of another method for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, including:

[0071] Step S201, obtaining first seismic depth domain velocity data and first logging velocity data of a well point.

[0072] In the embodiment of the present application, the first logging velocity data is obtained by an acoustic test signal. The first seismic depth domain velocity data includes seismic depth domain velocity data at a well point and seismic depth domain velocity data at a non-well point. In the embodiment of the present application, the first seismic depth domain velocity data is represented by Vel-1.

[0073] Step S202: determining a velocity mutation interval based on the first logging velocity data.

[0074] In an embodiment of the present application, a logging velocity smooth curve can be determined based on the first logging velocity data; the curvature change of each segment can be determined based on the logging velocity smooth curve; in the case where there is a curvature change greater than a preset threshold, the depth segment corresponding to the logging velocity smooth curve segment corresponding to the curvature change greater than the preset threshold is determined as a velocity mutation segment. In some embodiments, the velocity mutation segment can also be determined directly according to the data analysis method. In an embodiment of the present application, the top boundary layer and the bottom boundary layer of the velocity mutation segment can be determined based on the velocity mutation segment. The top boundary layer is represented by hor1, and the bottom boundary layer is represented by hor2.

[0075] Step S203, determining the second logging velocity data corresponding to the velocity mutation layer section and the third logging velocity data corresponding to the non-velocity mutation layer section in the first logging velocity data.

[0076] In an embodiment of the present application, after the velocity mutation layer section is determined, the second well logging velocity data and the third well logging velocity data in the first well logging data can be determined, the second well logging velocity data corresponds to the velocity mutation layer section, and the third well logging velocity data corresponds to the non-velocity mutation layer section. Exemplarily, after the first well logging data is smoothed, a well logging velocity smoothing curve is obtained, and the well logging velocity smoothing curve is assumed to be Vwell-ai, where a represents a depth point, and i represents a well point at different positions. In an embodiment of the present application, the well velocity of each depth point between hor1 and hor2 can be determined from Vwell-ai as Vwell-ai-h1. Vwell-ai-h1 is the second well logging velocity data, and the well velocity of each depth point other than hor1 and hor2 can be determined from Vwell-ai as Vwell-ai-h2, and Vwell-ai-h2 is the third well logging velocity data.

[0077] Step S204, determining fourth seismic depth-domain velocity data corresponding to the non-velocity mutation segment in the second seismic depth-domain velocity data.

[0078] In the embodiment of the present application, after the velocity mutation layer segment is determined, the second seismic depth domain velocity data at the well point can be extracted from the first seismic depth domain velocity data, and the eighth seismic depth domain velocity data corresponding to the velocity mutation layer segment and the fourth depth domain velocity data corresponding to the non-velocity mutation segment can be determined from the second address depth domain velocity data. Exemplarily, assuming that the second seismic depth domain velocity data is Vseis-ai, the seismic velocity data between hor1 and hor2 can be determined from Vseis-ai as Vseis-ai-h1, and Vseis-ai-h1 is the eighth seismic depth domain velocity data, and the seismic velocity data outside hor1 and hor2 can be determined from Vseis-ai as Vseis-ai-h2, and Vseis-ai-h2 is the fourth seismic depth domain velocity data.

[0079] Step S205, determining fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data.

[0080] Continuing with the above example, the fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point is represented by Vs-i. When calculating Vs-i, the depth position a in the velocity mutation layer section can be determined; the ratio of the fourth seismic depth domain velocity corresponding to the depth position a to the third logging velocity data corresponding to the depth position a can be determined; the product value of the second logging velocity data corresponding to the depth position a and the ratio can be determined; the product value is determined as the logging velocity corresponding to the depth position a. Thus, the fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point can be calculated. The calculation formula of the seismic velocity at the depth position a in the velocity mutation section at the well point is shown in formula (1):

[0081] Vs-i = Vwell-ai-h1 * ( Vseis-ai-h2 / Vwell-ai-h2 ) (1);

[0082] Step S206, determining sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth-domain velocity data.

[0083] In the embodiment of the present application, interpolation processing can be performed based on the fifth seismic depth-domain velocity data to determine the sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point.

[0084] Step S207, determining third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the fifth seismic depth-domain velocity data and the sixth seismic depth-domain velocity data.

[0085] In an embodiment of the present application, the fifth seismic depth domain velocity data and the sixth seismic depth domain velocity data can be merged to obtain the third seismic depth domain velocity data, and the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment is represented by Vel-2-a1.

[0086] Step S208: determining a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0087] In an embodiment of the present application, seventh seismic depth domain velocity data corresponding to each depth point in the first seismic depth domain velocity data is determined, wherein the seventh seismic depth domain velocity data is the same as each position point corresponding to the third seismic depth domain velocity data; the seventh seismic depth domain seismic velocity data is replaced by the third seismic depth domain velocity data to obtain target seismic velocity data; and a seismic velocity model is determined based on the target seismic velocity data.

[0088] Following the above example, Vel-1 corresponds to the seismic velocity between hor1 and hor2, which is the seventh seismic depth domain velocity data. The seventh seismic depth domain velocity data is replaced with Vel-2-a1 to obtain Vel-2-a2, which is the target seismic velocity data, and then the seismic velocity model is determined based on the target address velocity data.

[0089] The method for determining the third depth domain velocity model provided in the embodiment of the present application utilizes well data for constraints, improves the depth domain seismic velocity near the velocity mutation layer, and thereby improves the depth domain seismic velocity accuracy.

[0090] Embodiment 3

[0091] Based on the above embodiments, the present application further provides a method for determining a seismic depth domain velocity model. Figure 3 A schematic diagram of the implementation flow of another method for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, including:

[0092] Step S301, obtaining first seismic depth domain velocity data and first logging velocity data of a well point.

[0093] In the embodiment of the present application, the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point;

[0094] Step S302: determining a logging velocity smooth curve based on the first logging velocity data.

[0095] In the embodiment of the present application, the first logging data may be smoothed to obtain a logging velocity smooth curve, the resolution of which is greater than the resolution of the first seismic depth domain velocity data.

[0096] Step S303: determining the curvature change of each segment based on the logging velocity smoothing curve.

[0097] In the embodiment of the present application, the curvature change of the logging velocity smooth curve can be determined.

[0098] Step S304: when there is a curvature change greater than a preset threshold, the depth segment corresponding to the logging velocity smooth curve segment corresponding to the curvature change greater than the preset threshold is determined as a velocity mutation segment.

[0099] The preset threshold may be pre-set, and a depth segment corresponding to a curvature change greater than the preset threshold is a velocity mutation segment.

[0100] Step S305: determining third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first well logging velocity data and the second seismic depth-domain velocity data.

[0101] In an embodiment of the present application, the fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point can be determined based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; the sixth seismic depth domain velocity data corresponding to each depth point at the non-well point can be determined based on the fifth seismic depth domain velocity data; and the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer section can be determined based on the fifth seismic depth domain velocity data and the sixth seismic depth domain velocity data.

[0102] Step S306: determining a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0103] The method for determining the seismic depth domain velocity model provided in the embodiment of the present application obtains a smooth logging velocity curve by smoothing the first logging velocity data, and then determines the velocity mutation layer segment based on the logging velocity smooth curve, thereby determining the third depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second address depth domain velocity data, and replacing the data corresponding to each depth point in the first seismic depth domain velocity with the third depth domain velocity data, thereby determining the third seismic depth domain velocity model.

[0104] Embodiment 4

[0105] Based on the aforementioned embodiments, the embodiments of the present application further provide a method for determining a seismic depth domain velocity model, which can reduce the situation in which the tomography method is inaccurate in obtaining the velocity when the formation velocity suddenly changes during the seismic depth domain velocity modeling process, and use the logging data to constrain and correct the seismic velocity model. Through well data constraints, combined with tomography iterations based on seismic data, a more realistic depth domain velocity model that reflects the velocity of the underground medium is ultimately obtained, and the imaging effect is more accurate. It provides a more reliable data basis for well location deployment in oil and gas exploration and development. Figure 4 A schematic diagram of the implementation flow of a method for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the method includes:

[0106] Step S401, smooth the logging velocity in the depth domain to obtain a logging velocity smoothing curve Vwell-ai (same as the first logging velocity data in the above embodiment) with a resolution slightly greater than the seismic depth domain velocity resolution. i = 1, 2, 3.... i represents well points at different locations (i represents the same meaning in the following text).

[0107] Step S402, let the seismic depth domain velocity at this time be Vel-1 (same as the first seismic depth domain velocity data in the above embodiment), and determine the top layer position of the corresponding seismic data layer segment for the well layer with velocity mutation (same as the velocity mutation layer segment in the above embodiment). Let the corresponding layer segment top boundary layer position be hor1, and the bottom boundary layer position be hor2. Extract the depth domain seismic velocity curve Vseis-ai at each well point (same as the second seismic depth domain velocity data in the above embodiment).

[0108] Step S403, recalculate the velocity between hor1 and hor2 using Vseis-ai and Vwell-ai, and splice it with the velocity outside the hor1 and hor2 segments of the original Vel-1 to obtain Vel-2 (the same as the target seismic velocity data in the above embodiment).

[0109] Step S403 can be implemented by the following steps:

[0110] Step S4031, determine that the current seismic velocity between hor1 and hor2 is Vel-1-h1.

[0111] Step S4032, determine the seismic velocity other than the current hor1 and hor2 as Vel-1-h2.

[0112] Step S4033, determine the seismic velocity between hor1 and hor2 at the corresponding well point as Vseis-ai-h1 (the same as the eighth seismic depth domain velocity data in the above embodiment).

[0113] Step S4034, determining the seismic velocity other than hor1 and hor2 at the corresponding well point as Vseis-ai-h2 (the same as the fourth seismic depth domain velocity data in the above embodiment).

[0114] Step S4035, determining that the well velocity between hor1 and hor2 corresponding to the current logging velocity smooth curve Vwell-ai is Vwell-ai-h1 (the same as the second logging velocity data in the above embodiment).

[0115] Step S4036, determining that the well velocity other than hor1 and hor2 corresponding to the current logging velocity smooth curve Vwell-ai is Vwell-ai-h2 (the same as the third logging velocity data in the above embodiment).

[0116] Step S4037, the calculated seismic velocity at the well point used for replacement between hor1 and hor2 is Vs-i,

[0117] Vs-i=Vwell-ai-h1*(Vseis-ai-h2 / Vwell-ai-h2)

[0118] Step S4038, fill Vs-i between hor1 and hor2 at different well point locations, interpolate the seismic velocity at non-well points between hor1 and hor2 using Vs-i, and obtain the seismic layer velocity body Vel-2-a1 between hor1 and hor2 after difference.

[0119] Step S4039, replace the seismic velocity Vel-1 between hor1 and hor2 with Vel-2-a1 to obtain the overall seismic velocity Vel-2-a2.

[0120] Step S4040: perform volume smoothing of the longitudinal velocity value at the junction of hor1 and hor2 layers, and obtain Vel-2 after smoothing. Then, Vel-2 is the seismic velocity volume obtained after the well constraint calculation.

[0121] The method for determining the seismic depth domain velocity model provided in the embodiment of the present application determines that the velocity of the seismic depth domain velocity model near the velocity mutation layer is closer to the actual underground medium velocity, the seismic depth domain velocity model is more reliable, the corresponding imaging energy is more convergent, and the depth value of the imaging data body is closer to the actual underground depth.

[0122] A method for determining a seismic depth domain velocity model provided in an embodiment of the present application is applied to the Sinopec Xinjiang Tahe exploration area, where the main target layer is the Ordovician. The Ordovician is a marine stratum with a carbonate lithology. Above its top interface t74 is a continental stratum with a clastic lithology. The well velocities above and below the t74 interface change dramatically, and the general velocity difference is between 300m / s and 1000m / s. The logging velocity basically reflects the true velocity of the underground medium. Conventional tomographic velocity inversion driven by seismic data cannot obtain seismic velocity values ​​close to the well velocity near t74. Moreover, the target bead imaging below t74 is very non-convergent, and there is often an imaging tailing phenomenon. This inaccurate imaging stems from the inaccuracy of the velocity model.

[0123] Figure 5 A schematic diagram of a comparison between an unoptimized seismic velocity and a well velocity is provided in an embodiment of the present application, such as Figure 5 As shown in the figure, the well velocities of multiple well points are compared with the seismic velocities. Figure 5 In the figure, the seismic velocity changes relatively slowly. The relatively slow curve is the seismic velocity curve. Near the t74 layer, the seismic velocity is quite different from the well velocity. From the Y1 well point diagram, it can be seen that there is an obvious mutation in the well velocity curve under the t74 layer. The well velocity on t74 is basically 5000m / s, and the well velocity under t74 suddenly changes to about 5600m / s, with a velocity mutation of about 600m / s. After multiple rounds of tomographic iterations based on seismic data, the seismic velocity here still has no obvious improvement, that is, it is still in a state of continuous slow change.

[0124] Imaging by non-optimized seismic velocities, Figure 6 A schematic diagram of imaging based on unoptimized seismic velocity provided in an embodiment of the present application, such as Figure 6 As shown, in the current seismic velocity imaging effect, the target beads at the arrows and other places still have imaging tails, that is, the imaging energy convergence is poor and the imaging accuracy is insufficient.

[0125] Through seismic velocity modeling constrained by well velocity, the velocity between layers t74 and t80 is replaced to obtain new depth domain seismic velocity. The new seismic velocity is used for migration imaging. Figure 7 The following is a comparison chart of the imaging effects before and after the optimization provided in the embodiment of the present application, as shown in FIG. Figure 7 As shown, in Figure 7 In the figure, the left image is a schematic diagram of the effect before optimization, and the right image is a schematic diagram of the effect after optimization. The target bead tailing phenomenon at the arrow in the left image is more serious, while the tailing phenomenon of most beads in the right image is effectively corrected, the bead imaging is more focused, and some fault fractures are more prominent. That is, the new velocity model after optimization is more accurate and the imaging effect is better.

[0126] It should be noted that the embodiment of the present application provides an intermediate process of establishing a seismic velocity model using a determined seismic depth domain velocity model. After determining the seismic depth domain velocity model, conventional iterations need to be continued to obtain the final velocity model. In this example, based on the previous step, conventional tomography based on seismic data constraints is continued based on its offset imaging and offset gathers, and after multiple tomography iterations, the final offset velocity and imaging data volume are obtained.

[0127] Embodiment 5

[0128] Based on the foregoing embodiments, an embodiment of the present application provides a device for determining a seismic depth domain velocity model. The modules included in the device and the units included in each module can be implemented by a processor in a computer device; of course, they can also be implemented by a specific logic circuit; in the implementation process, the processor can be a central processing unit (CPU, Central Processing Unit), a microprocessor (MPU, Microprocessor Unit), a digital signal processor (DSP, Digital Signal Processing) or a field programmable gate array (FPGA, Field Programmable Gate Array), etc.

[0129] The present application embodiment provides a device for determining a seismic depth domain velocity model. Figure 8 A schematic diagram of a structure of a device for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Figure 8 As shown, the device 800 for determining the seismic depth domain velocity model includes:

[0130] An acquisition module 801 is used to acquire first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point;

[0131] A first determination module 802 is used to determine a velocity mutation layer section based on the first logging velocity data;

[0132] A second determination module 803 is used to determine third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second seismic depth domain velocity data;

[0133] The third determination module 804 is used to determine a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data.

[0134] In some embodiments, the second determining module 803 includes:

[0135] A first determining unit is used to determine second logging velocity data corresponding to the velocity mutation layer section in the first logging velocity data and third logging velocity data corresponding to the non-velocity mutation layer section;

[0136] A second determining unit is used to determine fourth seismic depth-domain velocity data corresponding to a non-velocity mutation segment in the second seismic depth-domain velocity data;

[0137] The third determining unit is used to determine the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation section based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data.

[0138] In some embodiments, the third determining unit includes:

[0139] A first determining subunit is used to determine fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data;

[0140] A second determination subunit is used to determine sixth seismic depth domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth domain velocity data;

[0141] The third determination subunit is used to determine the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the fifth seismic depth domain velocity data and the sixth seismic depth domain velocity data.

[0142] In some embodiments, the second determining subunit is used to perform interpolation processing based on the fifth seismic depth-domain velocity data to determine sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point.

[0143] In some embodiments, the first determination subunit is used to: determine a depth position a in the velocity mutation layer segment; determine the ratio of the fourth seismic depth domain velocity corresponding to the a depth position to the third logging velocity data corresponding to the a depth position; determine the product value of the second logging velocity data corresponding to the a depth position and the ratio; and determine the product value as the logging velocity corresponding to the a depth position.

[0144] In some embodiments, the third determination module 804 includes:

[0145] a fourth determining unit, configured to determine seventh seismic depth-domain velocity data corresponding to each depth point in the first seismic depth-domain velocity data, wherein the seventh seismic depth-domain velocity data is the same as each position point corresponding to the third seismic depth-domain velocity data;

[0146] a replacement unit, configured to replace the seventh seismic depth-domain seismic velocity data with the third seismic depth-domain velocity data to obtain target seismic velocity data;

[0147] A fifth determining unit is configured to determine a seismic velocity model based on the target seismic velocity data.

[0148] In some embodiments, the first determining module 802 includes:

[0149] a sixth determining unit, configured to determine a logging velocity smooth curve based on the first logging velocity data;

[0150] a seventh determination unit, configured to determine a curvature change of each segment based on the logging velocity smooth curve;

[0151] The eighth determination unit is used to determine, when there is a curvature change greater than a preset threshold, a depth segment corresponding to a logging velocity smooth curve segment corresponding to a curvature change greater than the preset threshold as a velocity mutation segment.

[0152] It should be noted that, in the embodiment of the present application, if the determination method of the above-mentioned seismic depth domain velocity model is implemented in the form of a software function module, and when it is sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM, Read Only Memory), a disk or an optical disk. In this way, the embodiment of the present application is not limited to any specific combination of hardware and software.

[0153] Accordingly, an embodiment of the present application provides a storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps in the method for determining a seismic depth domain velocity model provided in the above embodiment are implemented.

[0154] Embodiment 6

[0155] The embodiment of the present application provides a device for determining a seismic depth domain velocity model; Fig. 9 A schematic diagram of the structure of a device for determining a seismic depth domain velocity model provided in an embodiment of the present application is shown in FIG. Fig. 9As shown, the electronic device 900 includes: a processor 901, at least one communication bus 902, a user interface 903, at least one external communication interface 904, and a memory 905. The communication bus 902 is configured to realize the connection and communication between these components. The user interface 903 may include a display screen, and the external communication interface 904 may include a standard wired interface and a wireless interface. The processor 901 is configured to execute the program of the method for determining the seismic depth domain velocity model stored in the memory to implement the steps in the method for determining the seismic depth domain velocity model provided in the above embodiment.

[0156] The description of the above display device and storage medium embodiments is similar to the description of the above method embodiments, and has similar beneficial effects as the method embodiments. For technical details not disclosed in the computer device and storage medium embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0157] It should be noted here that the description of the above storage medium and device embodiments is similar to the description of the above method embodiments, and has similar beneficial effects as the method embodiments. For technical details not disclosed in the storage medium and device embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0158] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned sequence numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments.

[0159] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0160] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0161] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0162] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0163] A person of ordinary skill in the art can understand that: all or part of the steps of implementing the above-mentioned method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above-mentioned method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM, Read Only Memory), disks or optical disks, etc. Various media that can store program codes.

[0164] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can essentially or in other words, the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a controller to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0165] The above is only an implementation method of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for determining a seismic depth domain velocity model, characterized in that: include: Acquire first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point; Determine a velocity mutation interval based on the first logging velocity data; Determine third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first well logging velocity data and the second seismic depth domain velocity data; Determine a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data; The determining, based on the first well logging velocity data and the second seismic depth domain velocity data, third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer section comprises: Determine the second well logging velocity data corresponding to the velocity mutation layer section and the third well logging velocity data corresponding to the non-velocity mutation layer section in the first well logging velocity data; Determine fourth seismic depth-domain velocity data corresponding to the non-velocity mutation segment in the second seismic depth-domain velocity data; Determine the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation section based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; The determining, based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data, the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation section comprises: Determine fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; Determine sixth seismic depth domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth domain velocity data; The third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment is determined based on the fifth seismic depth-domain velocity data and the sixth seismic depth-domain velocity data.

2. The method according to claim 1, characterized in that The method of determining the sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth-domain velocity data comprises: Interpolation processing is performed based on the fifth seismic depth-domain velocity data to determine sixth seismic depth-domain velocity data corresponding to each depth point at the non-well point.

3. The method according to claim 1, characterized in that The determining, based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data, fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point comprises: Determine the depth position of a in the velocity mutation layer; Determine a ratio of a fourth seismic depth domain velocity corresponding to the depth position a to a third well logging velocity data corresponding to the depth position a; Determine a product value of the second logging velocity data corresponding to the depth position a and the ratio; The product value is determined as the logging velocity corresponding to the depth position a.

4. The method according to claim 1, characterized in that The determining of the seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data comprises: Determine seventh seismic depth-domain velocity data corresponding to each depth point in the first seismic depth-domain velocity data, wherein the seventh seismic depth-domain velocity data is the same as each position point corresponding to the third seismic depth-domain velocity data; Replacing the seventh seismic depth-domain velocity data with the third seismic depth-domain velocity data to obtain target seismic velocity data; A seismic velocity model is determined based on the target seismic velocity data.

5. The method according to claim 1, characterized in that The determining of the velocity mutation section based on the first logging velocity data comprises: Determine a logging velocity smooth curve based on the first logging velocity data; Determining the curvature change of each section based on the logging velocity smooth curve; In the case where there is a curvature change greater than a preset threshold, the depth segment corresponding to the logging velocity smooth curve segment corresponding to the curvature change greater than the preset threshold is determined as a velocity mutation segment.

6. A device for determining a seismic depth domain velocity model, characterized in that: include: An acquisition module, used for acquiring first seismic depth domain velocity data and first well logging velocity data of a well point, wherein the first seismic depth domain velocity data includes: second seismic depth domain velocity data at the well point; A first determination module, configured to determine a velocity mutation layer interval based on the first logging velocity data; A second determination module is used to determine third seismic depth domain velocity data corresponding to each depth point in the velocity mutation layer segment based on the first logging velocity data and the second seismic depth domain velocity data; A third determination module, configured to determine a seismic depth-domain velocity model based on the third seismic depth-domain velocity data and the first seismic depth-domain velocity data; The second determination module is further used to determine the second logging velocity data corresponding to the velocity mutation layer section in the first logging velocity data and the third logging velocity data corresponding to the non-velocity mutation layer section; Determine fourth seismic depth-domain velocity data corresponding to the non-velocity mutation segment in the second seismic depth-domain velocity data; Determine the third seismic depth domain velocity data corresponding to each depth point in the velocity mutation section based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; The second determination module is further used to determine fifth seismic depth domain velocity data corresponding to each depth point in the velocity mutation section at the well point based on the second well logging velocity data, the third well logging velocity data and the fourth seismic depth domain velocity data; Determine sixth seismic depth domain velocity data corresponding to each depth point at the non-well point based on the fifth seismic depth domain velocity data; The third seismic depth-domain velocity data corresponding to each depth point in the velocity mutation layer segment is determined based on the fifth seismic depth-domain velocity data and the sixth seismic depth-domain velocity data.

7. A device for determining a seismic depth domain velocity model, characterized in that: The method comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for determining a seismic depth domain velocity model according to any one of claims 1 to 5 is executed.

8. A storage medium, characterized in that: The computer program stored in the storage medium can be executed by one or more processors and can be used to implement the method for determining a seismic depth domain velocity model as claimed in any one of claims 1 to 5.

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