Method and device for establishing whole-area three-dimensional high-precision velocity field in oilfield development stage

Abstract

The invention is suitable for the technical field of petroleum geophysical prospecting, and discloses a method and device for establishing a whole-area three-dimensional high-precision velocity field in an oilfield development stage, and the method comprises the steps: collecting three-dimensional seismic data, stratigraphic layering data and well data of a research area in the oilfield development stage; based on the three-dimensional seismic data, the stratigraphic layering data and the well data, obtaining an average velocity curve of a single well in the research area in the oilfield development stage; establishing a time-domain three-dimensional grid system based on a time-domain seismic interpretation horizon in the three-dimensional seismic data; sampling the average velocity curve of the single well and the seismic average velocity body into a time domain three-dimensional grid system; based on the seismic average velocity body constraint, performing co-Kriging interpolation on the average velocity of the single well to obtain a time domain three-dimensional well seismic velocity body; and a high-precision three-dimensional velocity field is obtained based on a velocity model established by the time-domain three-dimensional well seismic velocity body. According to the technical scheme, the precision of the velocity field model is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of petroleum geophysical exploration technology, and in particular to a method, apparatus, equipment and medium for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development stage. Background Technology

[0002] The establishment of a three-dimensional velocity field is fundamental to oil and gas exploration and development, directly affecting the accuracy of single-well trajectory design and three-dimensional geological models. In the mid-stage of oilfield development, due to the numerous development layers, the requirements for the velocity field are even higher. Furthermore, mid-stage oilfields generally face numerous single wells with small well spacing (500-800 meters), resulting in three main problems in the practical application of velocity models: 1) It is difficult to uniformly characterize the velocities of all reservoirs within the study area using a single well or seismic velocity model; 2) Conventional velocity field structural accuracy is low, with significant differences in structural depth and stratification depth at single well locations; 3) Poor well-seismic coordination, with numerous bullseye phenomena at deep structural layers, severely affecting the construction of three-dimensional structural models. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a method, apparatus, equipment, and medium for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase. It fully utilizes three-dimensional seismic data within the oilfield, transforming the pre-stack depth migration velocity volume into a seismic average velocity volume, which is then used as a trend constraint. The three-dimensional velocity field constructed by combining the average velocity curves of all reservoir segments significantly improves the accuracy of the velocity field model.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase, comprising:

[0006] Collect 3D seismic data, stratigraphic data, and well data of the study area during the oilfield development phase;

[0007] Based on 3D seismic data, stratigraphic data, and well data, the average velocity curve of a single well in the study area during the oilfield development stage was obtained.

[0008] A time-domain three-dimensional grid system is established based on the temporal seismic interpretation horizon in three-dimensional seismic data.

[0009] The average velocity curves and seismic average velocity volumes of a single well are sampled into a time-domain three-dimensional grid system;

[0010] Based on the seismic mean velocity volume constraint, cokriging interpolation is performed on the single-well mean velocity to obtain the time-domain three-dimensional well seismic velocity volume.

[0011] A high-precision three-dimensional velocity field is obtained by establishing a velocity model based on the three-dimensional well seismic velocity volume in the time domain.

[0012] Furthermore, based on 3D seismic data, stratigraphic data, and well data, the average velocity curves of individual wells in the study area during the oilfield development stage were obtained, including:

[0013] Based on 3D seismic data, stratigraphic data, and well data, well seismic calibration was performed on individual wells in the study area;

[0014] Based on the results of well seismic calibration, the time-depth relationship curves of individual wells in the study area were obtained;

[0015] Based on the time-depth relationship curve, the average velocity curve of a single well in the study area is obtained.

[0016] Furthermore, the formula for calculating the time-depth relationship curve of a single well in the study area is as follows:

[0017]

[0018] In the formula, Vavg n Z is the average velocity from the reference surface to the nth stratum. n Z0 is the top depth of the nth stratum, Z0 is the depth of the reference surface, and T is the depth of the reference surface. n T0 is the acoustic travel time at the top of the nth stratum, and T0 is the acoustic travel time at the reference surface.

[0019] Furthermore, the average velocity curves and seismic average velocity volumes of individual wells are sampled into a time-domain three-dimensional grid system, including:

[0020] The average velocity curve of a single well is sampled into a three-dimensional grid system in the time domain using the arithmetic mean method;

[0021] The average velocity curves of individual wells are spliced ​​together to form an average velocity curve that covers all reservoir segments vertically.

[0022] The average velocity volume of earthquakes is obtained based on the pre-stack depth migration velocity volume of 3D seismic data.

[0023] The arithmetic mean method is used to sample the seismic average velocity volume into a time-domain three-dimensional grid system.

[0024] Furthermore, the calculation formula for the three-dimensional well seismic velocity volume in the time domain is obtained as follows:

[0025]

[0026] In the formula, For the Kriging method to predict velocity values ​​at unknown grid locations, n1 is the number of grids in the 3D grid system containing single-well average velocities, a1 is the grid count marker, ranging from 1 to n1, n2 is the number of grids in the 3D grid system containing seismic post-stack average velocities, a2 is the grid count marker, ranging from 1 to n2, Y(v a1 () represents the average velocity within the grid at a single well. The post-stack average velocity of earthquakes within the grid. and These are the interpolation weights.

[0027] Secondly, the present invention also provides a device for establishing a three-dimensional high-precision velocity field for the entire oilfield development stage, comprising:

[0028] The data collection module is used to collect 3D seismic data, stratigraphic data, and well data of the study area during the oilfield development phase.

[0029] The first module is used to obtain the average velocity curve of a single well in the study area during the oilfield development stage, based on three-dimensional seismic data, stratigraphic data, and well data.

[0030] The first module is used to establish a time-domain three-dimensional grid system based on the time-domain seismic interpretation horizon in the three-dimensional seismic data.

[0031] The sampling module is used to sample the average velocity curves and seismic average velocity volumes of a single well into a time-domain three-dimensional grid system.

[0032] The second module is used to perform cokriging interpolation on the average velocity of a single well based on the seismic average velocity volume constraint to obtain a three-dimensional well seismic velocity volume in the time domain.

[0033] The second module is used to establish a velocity model based on the three-dimensional well seismic velocity volume in the time domain, thereby obtaining a high-precision three-dimensional velocity field.

[0034] Furthermore, the first module is also used for:

[0035] Based on 3D seismic data, stratigraphic data, and well data, well seismic calibration was performed on individual wells in the study area;

[0036] Based on the results of well seismic calibration, the time-depth relationship curves of individual wells in the study area were obtained;

[0037] Based on the time-depth relationship curve, the average velocity curve of a single well in the study area is obtained.

[0038] Furthermore, the formula for calculating the time-depth relationship curve of a single well in the study area is as follows:

[0039]

[0040] In the formula, Vavg n Z is the average velocity from the reference surface to the nth stratum. n Z0 is the top depth of the nth stratum, Z0 is the depth of the reference surface, and T is the depth of the reference surface. n T0 is the acoustic travel time at the top of the nth stratum, and T0 is the acoustic travel time at the reference surface.

[0041] Furthermore, the sampling module is also used for:

[0042] The average velocity curve of a single well is sampled into a three-dimensional grid system in the time domain using the arithmetic mean method;

[0043] The average velocity curves of individual wells are spliced ​​together to form an average velocity curve that covers all reservoir segments vertically.

[0044] The average velocity volume of earthquakes is obtained based on the pre-stack depth migration velocity volume of 3D seismic data.

[0045] The arithmetic mean method is used to sample the seismic average velocity volume into a time-domain three-dimensional grid system.

[0046] Furthermore, the calculation formula for the three-dimensional well seismic velocity volume in the time domain is obtained as follows:

[0047]

[0048] In the formula, For the Kriging method to predict velocity values ​​at unknown grid locations, n1 is the number of grids in the 3D grid system containing single-well average velocities, a1 is the grid count marker, ranging from 1 to n1, n2 is the number of grids in the 3D grid system containing seismic post-stack average velocities, a2 is the grid count marker, ranging from 1 to n2, Y(v a1 () represents the average velocity within the grid at a single well. The post-stack average velocity of earthquakes within the grid. and These are the interpolation weights.

[0049] Thirdly, the present invention also provides an electronic device, comprising: a processor and a memory;

[0050] The processor is coupled with the memory;

[0051] The processor is used to read and execute programs or instructions stored in the memory, causing the device to perform the method as described in the first aspect.

[0052] Fourthly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method as described in the first aspect.

[0053] In summary, the technical solution provided by this invention has at least the following technical effects or advantages:

[0054] The technical solution of this invention involves collecting 3D seismic data, stratigraphic data, and well data from the study area during the oilfield development phase. Based on well-seismic calibration of individual wells within the study area, average velocity curves for shallow, intermediate, and deep layers corresponding to each well are obtained. These average velocity curves are then cut and spliced ​​according to the top and bottom depths of the formations to obtain average velocity curves covering all reservoir segments vertically. The average velocity curves of all reservoir segments are combined with seismic average velocity volume trend constraints to perform velocity modeling, resulting in a high-precision 3D velocity field. This technical solution fully utilizes the 3D seismic data, stratigraphic data, and well data within the oilfield. By converting the pre-stack seismic depth migration velocity volume into a seismic average velocity volume and using it as a trend constraint, the 3D velocity field constructed by combining the average velocity curves of all reservoir segments significantly improves the accuracy of the velocity field model and solves the bullseye problem caused by a large number of wells, providing technical conditions for subsequent geological modeling research.

[0055] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 This is a flowchart illustrating a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase, as described in an embodiment of the present invention.

[0058] Figure 2 This is a further flowchart illustrating a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase, as described in an embodiment of the present invention.

[0059] Figure 3 This is a schematic diagram comparing the structures obtained from conventional velocity fields and high-precision velocity fields in an embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of a device for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development stage, as described in an embodiment of the present invention.

[0061] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] Figure 1 This is a flowchart illustrating a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase, as described in an embodiment of the present invention. Figure 2 This is a further flowchart illustrating a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development phase, as described in an embodiment of the present invention; the following is in conjunction with... Figure 1 and Figure 2 Further illustrating the technical solution of the present invention, as shown in the figure, a method for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development stage includes:

[0064] S101. Collect 3D seismic data, stratigraphic data, and well data of the study area during the oilfield development phase;

[0065] The study area during the oilfield development phase refers to the area delineated according to the needs of the project research. In the oilfield development phase, the study area includes both horizontal and vertical dimensions. The horizontal dimension of the study area refers to the oilfield mining rights area; in terms of data, it also refers to the area covered by 3D seismic data. The vertical dimension of the study area refers to all reservoir segments covered, i.e., all stratigraphic layers. 3D seismic data for the study area is collected, including: 3D seismic SEGY data volumes, pre-stack depth-migration velocity volumes, and time-domain seismic interpretation horizons. 3D seismic data is used to construct a time-domain 3D grid and constrain subsequent velocity differences. Target stratigraphic and well data within the study area are collected, including: wellhead coordinates, well trajectory, sonic transit time curves, and density curves. Target stratigraphic layers refer to the top and bottom of the oil-bearing strata within the study area that are of key interest. Sonic transit time curves and density curves are used to calculate the time-depth relationship within the stratigraphic layers corresponding to individual wells within the study area, further obtaining the average velocity curve within the stratigraphic layers, also known as the average velocity curve of a single well. Wellhead coordinates and well trajectory are used to determine the grid location for sampling the average velocity curve in the 3D grid system. Formation stratification data and well data also include: logging data, well logging information, and formation thickness of individual wells; used to verify the accuracy of formation depth at individual well locations.

[0066] S102. Based on 3D seismic data, stratigraphic data, and well data, the average velocity curve of a single well in the study area during the oilfield development stage is obtained.

[0067] Based on different frequency ranges of seismic reflection waves (e.g., 45-50 Hz, 40-45 Hz, and 30-40 Hz), stratigraphic data, and well data from 3D seismic data, well-seismic calibration was performed on the shallow, intermediate, and deep layers corresponding to individual wells in the study area. Using the sonic transit time and density curves from the stratigraphic and well data, reflection coefficient curves for individual wells in the study area were generated. These curves were then convolved using seismic wavelets to obtain artificially synthesized seismic reflection curves for each well. Morphological comparison and correlation analysis were performed between these reflection curves and the reflection characteristics of time-domain seismic interpretation stratigraphic data to obtain time-depth relationship curves for individual wells in the study area. These time-depth curves ensure the correct location of each well in the time-domain seismic interpretation stratigraphic data for the two-way travel time of sonic waves at different depths. Strata with stable reflection characteristics (amplitude, frequency, and phase) and oil-bearing strata (i.e., marker layers) in 3D seismic data are selected. Seismic reflection characteristics are used for tracing to obtain the top and bottom layers representing the selected strata in the time domain. For oil-bearing strata, it is necessary to perform stratification at single well locations within that segment, well-seismic calibration, and quality control on the seismic reflection characteristic tracing results.

[0068] Seismic reflection characteristics include: surface thickness, lithological stability, and reflection characteristics during the earthquake (amplitude, frequency, and phase). Using these seismic reflection characteristics, the top and bottom layers representing the selected strata are obtained in the time domain. This includes: tracing the reflection characteristics on time-domain seismic interpretation stratigraphic data to form the top and bottom layers representing the strata. The consistency between the layer depth and the well layer location is checked by comparing the layer depth with the well layer location. The correctness of the layer depth at a single well is confirmed using well logging data and the thickness of strata in adjacent wells. The correlation coefficient or fitting coefficient of the synthesized seismic reflection curve at the obtained single well is calculated using the single well location in the 3D seismic data to check the accuracy and consistency of well-seismic calibration, ensuring that the top and bottom layers of the selected marker layer are correctly located in the time-domain seismic interpretation stratigraphic data. The tracking results of the marker layer are analyzed using methods such as the stability of reflection characteristics in earthquakes, the differences in tracking layers in different directions, and the thickness between layers to ensure the stability and reliability of the tracking layers.

[0069] During the oilfield development phase, the study area contains more than one reservoir. Therefore, it is necessary to calculate the average velocity curves for the shallow, intermediate, and deep layers corresponding to all individual wells within the study area, i.e., the average velocity curves for each well. The average velocity can be obtained using a layered medium model and the time-depth relationship curve of each well. The calculation formula is as follows:

[0070]

[0071] In the formula, Vavg n Z is the average velocity from the reference surface to the nth stratum. n Z0 is the top depth of the nth stratum, Z0 is the depth of the reference surface, and T is the depth of the reference surface. n Let T0 be the acoustic travel time at the top of the nth formation, and T0 be the acoustic travel time at the reference surface. The average velocity curve obtained by formula (1) can be regarded as a function of the formation average velocity and time at a single well.

[0072] S103. Based on the temporal seismic interpretation horizon in 3D seismic data, establish a temporal 3D grid system;

[0073] The time-domain seismic interpretation horizons in the 3D seismic data of the study area contain information on stratigraphic plane coordinates and longitudinal acoustic reflection travel times. Based on the time-domain seismic interpretation horizons and the longitudinal reservoir distribution range of the wells in the study area, a time-domain 3D grid system is established by defining the planar and longitudinal grid sizes. Parameters such as the lateral size and orientation of the grids are set on the plane, and the grids are divided into rectangles or squares. The longitudinal thickness of the grids is set, and the vertical grids are divided using equal or proportional methods. The more grids generated, the higher the accuracy of the velocity model; the number of grids is determined according to actual needs. The size of each grid is determined by considering the seismic longitudinal resolution and the total number of grids in the study area, balancing the accuracy of the velocity model with computational speed. The input data for the time-domain 3D grid system is the time-domain seismic interpretation horizons, selected from horizons with obvious and stable seismic inverse-hand characteristics.

[0074] S104, the average velocity curve of a single well and the seismic average velocity volume are sampled into a time-domain three-dimensional grid system;

[0075] The average velocity curves of individual wells within the aforementioned study area were sampled into a time-domain 3D grid system using the arithmetic mean method. The average velocity curves of shallow, intermediate, and deep layers corresponding to each well were then stitched together to form an average velocity curve covering all reservoir segments vertically. The seismic average velocity volume can be calculated using the Dix formula from the pre-stack depth migration velocity volume in 3D seismic data, and then sampled into the time-domain 3D grid system using the arithmetic mean method. The calculation formula for sampling the average velocity curves of individual wells corresponding to each formation layer within the aforementioned study area into the time-domain 3D grid system using the arithmetic mean method is as follows:

[0076]

[0077] In the formula, V aV represents the average velocity at a single well and a single grid. i For each average velocity curve contained in the grid, N is the number of average velocity curve sampling points contained in the grid, and i is a counter, with a value from 1 to N.

[0078] S105. Based on the seismic mean velocity volume constraint, cokriging interpolation is performed on the single-well mean velocity to obtain the time-domain three-dimensional well seismic velocity volume.

[0079] Variation function analysis is performed on the average velocity of a single well. Specific analysis parameters include the primary range, secondary range, azimuth, nugget value, sill value, and variation function type, resulting in a suitable variation function model. This model is used to calculate two weights in the cokriging interpolation: a redundancy weight to characterize the relationship between known velocity grids, and an estimation weight to characterize the relationship between known velocity samples and unknown velocity grids. These two weights determine the accuracy of the velocity interpolation in the 3D mesh system. In the time-domain 3D mesh system, cokriging interpolation is performed on the average velocity of a single well using seismic mean velocity volume trend constraints to obtain the time-domain 3D well-seismic velocity volume.

[0080] The average velocity of a formation is typically influenced by geological conditions such as structure, lithology, and fluids, and its variations exhibit a relatively clear trend. Therefore, simply using the average velocity at a single well for kriging interpolation within a three-dimensional grid system cannot accurately characterize the complex variations in formation velocity. Thus, it is necessary to use the seismic average velocity volume as a second variable to constrain the effectiveness of kriging interpolation of the average velocity at a single well within a time-domain three-dimensional grid system. A time-domain three-dimensional well-seismic velocity volume is established, and the calculation formula is as follows:

[0081]

[0082] In the formula, For the Kriging method to predict velocity values ​​at unknown grid locations, n1 is the number of grids in the 3D grid system containing single-well average velocities, a1 is the grid count marker, ranging from 1 to n1, n2 is the number of grids in the 3D grid system containing seismic post-stack average velocities, a2 is the grid count marker, ranging from 1 to n2, Y(v a1 () represents the average velocity within the grid at a single well. The post-stack average velocity of earthquakes within the grid. and These are the interpolation weights.

[0083] S106. A high-precision three-dimensional velocity field is obtained by establishing a velocity model based on the three-dimensional well seismic velocity volume in the time domain.

[0084] Based on the aforementioned three-dimensional well-seismic velocity volume in the time domain, a velocity model is established by interpreting the time of the strata and their corresponding average velocities in the time domain seismic interpretation. Then, well-level correction is performed on the velocities corresponding to geological strata at individual wells in the velocity model to obtain a high-precision three-dimensional velocity field.

[0085] The time-depth transformation of the aforementioned high-precision three-dimensional velocity field is calculated using the following formula:

[0086] Z = Z0 + V avg (t-t0) (4)

[0087] In the formula, V avg The field is a three-dimensional average velocity field, where t is the sound wave reflection time at a specific stratum, and t0 is the sound wave reflection time at sea level. Z0 is the sea level depth, and Z is the depth of the specific stratum after time-depth conversion.

[0088] The accuracy of the velocity field time-depth conversion is mainly based on the comparison between the layer that has been converted from the velocity field to the depth domain and the layer depth of a single well.

[0089] To meet the accuracy requirements of geological models and subsequent reservoir development, the stratigraphic levels converted to the depth domain must satisfy the following three requirements:

[0090] 1. The depth of the depth domain layer does not differ significantly from the depth of well stratification in a single well (the error is generally 3-5‰);

[0091] 2. The data of depth domain layer and well layer residuals are randomly distributed, with no obvious distribution trend;

[0092] 3. There is no sudden thinning or thickening of the thickness between layers in the depth domain.

[0093] In summary, the technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0094] The technical solution of this invention involves collecting 3D seismic data, stratigraphic data, and well data from the study area during the oilfield development phase. Based on well-seismic calibration of individual wells within the study area, average velocity curves for the shallow, intermediate, and deep layers corresponding to each well are obtained. According to the top and bottom depths of the formations, the average velocity curves are cut and spliced ​​to obtain average velocity curves covering all reservoir segments vertically. These average velocity curves are then combined with seismic average velocity volume trend constraints to perform velocity modeling, resulting in a high-precision 3D velocity field. This invention fully utilizes the 3D seismic data, stratigraphic data, and well data within the oilfield, converting the pre-stack seismic depth migration velocity volume into a seismic average velocity volume as a trend constraint. The resulting 3D velocity field, constructed by combining the average velocity curves of all reservoir segments, significantly improves the accuracy of the velocity field model.

[0095] The above-mentioned technical solution was used to establish a three-dimensional velocity model for a large carbonate oilfield, accurately converting the time-domain three-dimensional seismic interpretation results into depth-domain results, improving the accuracy of structural interpretation to 3‰, and solving the bullseye problem caused by the large number of wells, thus providing technical conditions for subsequent geological modeling research.

[0096] For example, in a large carbonate oilfield with multiple reservoirs developed vertically, a three-dimensional velocity model of the entire area is established, including the following steps:

[0097] (1) Establish a three-dimensional mesh in the time domain

[0098] Using time-domain 3D interpretation of stratigraphy, and based on the project's technical requirement that the difference between depth-domain stratigraphy and single-well stratigraphy be less than 5‰, stratigraphy with stable seismic reflection characteristics and thickness was selected as the framework for the 3D mesh. A time-domain 3D mesh system was constructed. In this mesh system, the mesh size takes into account both the seismic vertical resolution and the total number of meshes in the study area. The vertical dimension of the mesh is close to the seismic vertical resolution. This mesh is a time-domain mesh.

[0099] (2) Average velocity calculation and sampling

[0100] The average velocity of a single well was calculated using the time-depth curves obtained from well-seismic calibration, and then sampled into a three-dimensional grid using the arithmetic mean method. Since well-seismic calibration is performed separately for different formations, after sampling the average velocity of a single well into the three-dimensional grid, the average velocity of a single well was segmented, cut, and spliced ​​for different reservoirs to establish a sample point of average velocity of a single well across the entire area in the three-dimensional grid.

[0101] (3) Seismic velocity conversion and sampling

[0102] The pre-stack depth migration velocity volume (time domain) of the earthquake is converted into average velocity using the Dix formula and then sampled into a three-dimensional time domain mesh.

[0103] (4) Establish a three-dimensional velocity model

[0104] Using single-well average velocity samples as input, and under the trend constraint of the seismic average velocity volume, reasonable variation function parameters are set, and a cokriging interpolation algorithm is employed to establish a well-seismic combined three-dimensional velocity volume. Based on this, well-level correction is performed to establish a three-dimensional velocity field for the entire region.

[0105] (5) Error Analysis

[0106] Quality control included error analysis at individual wells and stratigraphic thickness checks. Histograms of depth-domain and individual well stratigraphic residuals showed that at a depth of approximately 2800m, the residual values ​​at 258 individual wells were approximately 5-10 meters (accuracy ≤ 3‰), and exhibited a random distribution (average residual value approximately 0). No significant bullseye or thickness anomalies were observed between stratigraphic layers. Figure 3As shown, the structure obtained from the conventional velocity field on the left has bullseyes, while the structure obtained from the high-precision velocity field on the right does not. Therefore, the accuracy of this velocity model can meet the needs of subsequent geological modeling and reservoir development.

[0107] Figure 4 This is a schematic diagram of a device for establishing a three-dimensional high-precision velocity field across an entire oilfield during the development stage, as provided in an embodiment of the present invention. The device includes:

[0108] The data collection module is used to collect 3D seismic data, stratigraphic data, and well data of the study area during the oilfield development phase.

[0109] The module is used to obtain the average velocity curve of a single well in the study area during the oilfield development stage, based on 3D seismic data, stratigraphic data, and well data.

[0110] A module is established to create a time-domain 3D grid system based on the time-domain seismic interpretation horizon in 3D seismic data.

[0111] The sampling module is used to sample the average velocity curves and seismic average velocity volumes of a single well into a time-domain three-dimensional grid system.

[0112] The module is also used to perform cokriging interpolation on the average velocity of a single well based on the seismic mean velocity volume constraint, to obtain a three-dimensional well seismic velocity volume in the time domain.

[0113] The module is also used to establish a velocity model based on a three-dimensional well seismic velocity volume in the time domain, thereby obtaining a high-precision three-dimensional velocity field.

[0114] It should be noted that, for ease of explanation, Figure 4 This example only illustrates the main modules of a three-dimensional high-precision velocity field establishment device for the entire oilfield development stage. In practical applications, the system may also include modules or components not shown in the figure; the system is not limited to the above-described module structure, but may also be other module structures that implement the above method embodiments.

[0115] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0116] like Figure 5 As shown, the electronic device includes: a processor and a memory;

[0117] The processor is used to read and execute programs and instructions stored in the memory, causing the electronic device to perform the above-described method embodiments.

[0118] It should be noted that, for ease of explanation, Figure 5 Only the main components of the electronic device are shown. In actual applications, the electronic device may also include components or assemblies not shown in the figure.

[0119] The present invention also provides a computer-readable storage medium storing a program or instructions, which, when read and executed by a computer, causes the computer to perform the above-described method embodiments.

[0120] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for establishing a full-area three-dimensional high-precision velocity field in an oilfield development stage, characterized in that, The method comprises the following steps: collecting three-dimensional seismic data, stratum layering data and well data of a research area in an oilfield development stage; obtaining average velocity curves of single wells in the research area in the oilfield development stage based on the three-dimensional seismic data, the stratum layering data and the well data; establishing a time-domain three-dimensional grid system based on time-domain seismic interpretation horizons in the three-dimensional seismic data; sampling the average velocity curves of the single wells and a seismic average velocity body into the time-domain three-dimensional grid system; performing co-Kriging interpolation on the average velocity of the single wells based on the seismic average velocity body constraint to obtain a time-domain three-dimensional well-seismic velocity body; obtaining a high-precision three-dimensional velocity field based on a velocity model established based on the time-domain three-dimensional well-seismic velocity body.

2. The method according to claim 1, wherein, The method for obtaining the average velocity curves of the single wells in the research area in the oilfield development stage based on the three-dimensional seismic data, the stratum layering data and the well data comprises the following steps: performing well-seismic calibration on the single wells in the research area according to the three-dimensional seismic data, the stratum layering data and the well data; obtaining time-depth relationship curves of the single wells in the research area according to the results of the well-seismic calibration; obtaining the average velocity curves of the single wells in the research area according to the time-depth relationship curves.

3. The method according to claim 1, wherein, The calculation formula for obtaining the time-depth relationship curves of the single wells in the research area is: where Vavg n is the average velocity of the n-th layer of strata from the datum, Z n is the depth of the top of the n-th layer of strata, Z0is the depth of the datum, T n is the acoustic travel time of the top of the n-th layer of strata, and T0is the acoustic travel time of the datum.

4. The method according to claim 1, wherein, The method for sampling the average velocity curves of the single wells and the seismic average velocity body into the time-domain three-dimensional grid system comprises the following steps: sampling the average velocity curves of the single wells into the time-domain three-dimensional grid system by using an arithmetic mean method; splicing the average velocity curves of the single wells to form average velocity curves covering all reservoir intervals in the vertical direction; obtaining a seismic average velocity body based on a seismic pre-stack depth migration velocity body in the three-dimensional seismic data; sampling the seismic average velocity body into the time-domain three-dimensional grid system by using the arithmetic mean method.

5. The method for establishing a full-field 3D high-precision velocity field in the oilfield development stage according to any one of claims 1-4, characterized in that, The calculation formula for obtaining the time-domain three-dimensional well-seismic velocity body is: wherein, is the predicted velocity value by Kriging method at unknown grid, n1 is the number of grids containing single well average velocity in three-dimensional grid system, a1 is the grid count marker, taking value from 1 to n1, n2 is the number of grids containing seismic post-stack average velocity in three-dimensional grid system, a2 is the grid count marker, taking value from 1 to n2, Y(v a1 ) is the average velocity in the grid at single well, is the average velocity in the grid at seismic post-stack, and are interpolation weights, respectively.

6. An apparatus for establishing a full-area three-dimensional high-precision velocity field in an oilfield development stage, characterized in that, The method comprises the following steps: a collecting module, configured to collect three-dimensional seismic data, stratum layering data and well data of a research area in an oilfield development stage; a first obtaining module, configured to obtain average velocity curves of single wells in the research area in the oilfield development stage based on the three-dimensional seismic data, the stratum layering data and the well data; a first establishing module, configured to establish a time-domain three-dimensional grid system based on time-domain seismic interpretation horizons in the three-dimensional seismic data; a sampling module, configured to sample the average velocity curves of the single wells and a seismic average velocity body into the time-domain three-dimensional grid system; a second obtaining module, configured to perform co-Kriging interpolation on the average velocity of the single wells based on the seismic average velocity body constraint to obtain a time-domain three-dimensional well-seismic velocity body; a second establishing module, configured to obtain a high-precision three-dimensional velocity field based on a velocity model established based on the time-domain three-dimensional well-seismic velocity body.

7. The device for establishing a full-zone 3D high-precision velocity field in the oilfield development stage according to claim 6, characterized in that, The first obtaining module is further configured to: perform well-seismic calibration on the single wells in the research area according to the three-dimensional seismic data, the stratum layering data and the well data; obtain time-depth relationship curves of the single wells in the research area according to the results of the well-seismic calibration; obtain the average velocity curves of the single wells in the research area according to the time-depth relationship curves.

8. The device for establishing a full-zone 3D high-precision velocity field in an oilfield development stage according to claim 6, characterized in that, The calculation formula for obtaining the time-depth relationship curves of the single wells in the research area is: where Vavg n is the average velocity of the n-th layer of strata from the datum, Z n is the depth of the top of the n-th layer of strata, Z0is the depth of the datum, T n is the acoustic travel time of the top of the n-th layer of strata, T0is the acoustic travel time of the datum.

9. The device for establishing a full-zone 3D high-precision velocity field in an oilfield development stage according to claim 6, characterized in that, The sampling module is further configured to: The average velocity curve of the single well is sampled into a time domain three-dimensional grid system by using an arithmetic average method; The average velocity curves of the single wells are spliced to form an average velocity curve covering all reservoir intervals in the vertical direction; A seismic average velocity body is obtained based on a pre-stack depth migration velocity body in three-dimensional seismic data; The seismic average velocity body is sampled into a time domain three-dimensional grid system by using an arithmetic average method.

10. The apparatus for establishing a full-field 3D high-precision velocity field of an oilfield development stage according to any one of claims 6-9, characterized in that, The calculation formula for obtaining the time domain three-dimensional well-seismic velocity body is: wherein, is the predicted velocity value by the kriging method at the unknown grid, n1 is the number of grids in the three-dimensional grid system containing the average velocity of single wells, a1 is the grid count marker, taking values from 1 to n1, n2 is the number of grids in the three-dimensional grid system containing the average velocity of seismic post-stack, a2 is the grid count marker, taking values from 1 to n2, Y(v a1 ) is the average velocity in the grid at the single well, is the average velocity in the grid of seismic post-stack, and are interpolation weights, respectively.

11. An electronic device, comprising: The device comprises: a processor and a memory; the processor is coupled with the memory; wherein the processor is configured to read and execute programs or instructions stored in the memory, so that the device executes the method according to any one of claims 1-5.

12. A computer-readable storage medium, characterized in that, The computer program is stored in the memory and is executed by the processor to implement the method according to any one of claims 1-5.

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