Well seismic information fusion velocity modeling, while-drilling seismic velocity modeling method and device

Abstract

The present invention discloses a method and apparatus for fusion velocity modeling and seismic velocity modeling while drilling (SWD) using well-seismic information. The method includes a wellpoint location velocity fusion step, wherein for each drilled well, a velocity difference curve between a VSP logging velocity curve and a surface seismic velocity volume is determined; a control node corresponding to each layer is determined based on the well's layered data; the average velocity between two adjacent control nodes is determined based on the well-seismic calibration results and the well's layered data; the velocity difference curve is smoothed using a cubic spline function curve simulation with the average velocity as a constraint; a fused velocity curve is obtained from the smoothed velocity difference curve and the seismic velocity volume; and a seismic velocity modeling step, wherein a velocity model is established using a co-kriging interpolation method with the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity volume. This method can improve the efficiency and accuracy of seismic velocity modeling.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method and device for well-seismic information fusion velocity modeling and while-drilling seismic velocity modeling. Background Art

[0002] Oil drilling is a high-investment, high-risk, concealed underground project. The underground conditions are characterized by significant ambiguity and uncertainty, posing significant risks to drilling operations. Therefore, during the drilling process, it is crucial to understand the various parameters of undrilled formations, as well as information on reservoir and fracture locations. When designing a well site, the processing and interpretation of seismic data, combined with drilling results from adjacent wells, provide a preliminary understanding of the current well's geology. As the well progresses, information about the drilled formations may differ significantly from previous geological understanding. If the geological understanding of the drilled formations differs significantly from previous understanding, the target designed based on previous understanding may differ significantly from the actual reservoir location. Therefore, it is necessary to re-predict the target location and adjust the drilling trajectory to improve the drilling success rate.

[0003] While drilling (VSP) technology allows real-time vertical seismic profiling (VSP) measurements during drilling, enabling real-time prediction of the stratigraphic structure around the wellbore and ahead of the drill bit. This technology offers the advantages of real-time measurement without sacrificing drilling time. However, instrument stability is significantly affected by well conditions, the drill bit requires high-quality engineering, and the cost is high, making it difficult to scale up. Currently, a simplified VSP seismic guidance while drilling (VSP) technology is widely used in China. This technology implements VSP logging just before drilling reaches the target layer. The acquired velocity information and time-depth relationship are used to modify the surface seismic velocity field and anisotropy parameters to obtain more accurate subsurface information, thereby determining the target location and optimizing the target trajectory. The core of this method is to rapidly update the structural model by obtaining accurate geological stratification through drilling and logging, obtain more refined formation velocities and Q values ​​through VSP measurements, implement surface seismic anisotropy depth migration processing, obtain high-quality seismic data, determine the target location through detailed reservoir prediction, and ultimately implement trajectory optimization and adjustment.

[0004] VSP seismic guidance processing while drilling (VSP) requires real-time drilling guidance, making accuracy and timeliness paramount. Currently, surface seismic anisotropic prestack depth migration processing typically takes over a month. Moreover, in the absence of nearby drilled wells, the accuracy is far from sufficient for precise target prediction. Velocity modeling is the most time-consuming step in VSP seismic guidance processing and has the greatest impact on accuracy. Therefore, developing an efficient and accurate velocity modeling method is essential for VSP seismic guidance processing while drilling. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a method and device for well-seismic information fusion velocity modeling and while-drilling seismic velocity modeling that overcomes the above problems or at least partially solves the above problems, which can improve the efficiency and accuracy of seismic velocity modeling.

[0006] In a first aspect, an embodiment of the present invention provides a method for velocity modeling by fusing well and seismic information, comprising:

[0007] The well point location velocity fusion step includes determining, for each drilled well, a velocity difference curve between a VSP logging velocity curve and a surface seismic velocity volume; determining a control node corresponding to each layer based on the well's layered data; determining an average velocity between two adjacent control nodes based on the well-seismic calibration results and the well's layered data; using the average velocity as a constraint, smoothing the velocity difference curve using a cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtaining a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume.

[0008] The seismic velocity modeling step is to establish a velocity model by using the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity volume.

[0009] In a second aspect, an embodiment of the present invention provides a method for seismic velocity modeling while drilling, comprising:

[0010] A work area establishment step, establishing a work area according to a while-drilling processing range of the well being drilled, determining the drilled wells within the work area, and extracting a surface seismic velocity volume within the work area;

[0011] The well point location velocity fusion step includes determining a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume for the well being drilled and each drilled well; determining the control node corresponding to each layer based on the well layer data; determining the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data; using the average velocity as a constraint, smoothing the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtaining a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume.

[0012] The seismic velocity modeling step is to establish a velocity model by using the surface seismic velocity body and the fused velocity curves of the well being drilled and each drilled well as constraints, thereby obtaining a fused surface seismic velocity body.

[0013] In a third aspect, an embodiment of the present invention provides a well-seismic information fusion velocity modeling device, comprising:

[0014] The well point location velocity fusion module is used to determine, for each drilled well, a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume; determine the control node corresponding to each layer based on the well's layered data; determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well's layered data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtain a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume;

[0015] The seismic velocity modeling module is used to establish a velocity model by using the surface seismic velocity body and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity body.

[0016] In a fourth aspect, an embodiment of the present invention provides a while-drilling seismic velocity modeling device, comprising:

[0017] A work area establishment module is used to establish a work area according to the drilling while drilling processing range of the well being drilled, determine the drilled wells in the work area, and extract the surface seismic velocity volume in the work area;

[0018] The well point location velocity fusion module is used to determine the velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume for each well being drilled and each drilled well; determine the control node corresponding to each layer based on the well layer data; determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtain a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume;

[0019] The seismic velocity modeling module is used to establish a velocity model by using the surface seismic velocity body and the fused velocity curves of the drilling well and each drilled well as constraints to obtain a fused surface seismic velocity body through the co-kriging interpolation method.

[0020] In a fifth aspect, an embodiment of the present invention provides a computer program product with seismic velocity modeling function, including a computer program / instruction, wherein when the computer program / instruction is executed by a processor, the above-mentioned well-seismic information fusion velocity modeling method is implemented, or the above-mentioned while-drilling seismic velocity modeling is implemented.

[0021] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0022] (1) The embodiment of the present invention provides a velocity modeling method for fusing well-seismic information. The well point location velocity fusion step is to determine the velocity difference curve between the VSP well logging velocity curve and the surface seismic velocity body for each drilled well; determine the control node corresponding to each layer according to the well stratification data; determine the average velocity between two adjacent control nodes according to the well seismic calibration results and the well stratification data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation; obtain a fused velocity curve from the smoothed velocity difference curve and the seismic velocity body; the seismic velocity modeling step is to establish a velocity model through the co-kriging interpolation method with the surface seismic velocity body and the fused velocity curve of at least one drilled well as constraints to obtain a fused surface seismic velocity body. Through mathematical algorithms such as cubic spline function simulation and co-kriging interpolation, the drilling information, VSP well logging information, and the existing surface seismic velocity body information are efficiently and accurately fused, so that the determined fused velocity vertical trend is consistent with the well information and the horizontal variation trend is consistent with the surface seismic velocity body, thereby improving the accuracy of velocity modeling. At the same time, using mathematical calculations instead of velocity iterations reduces the time consumed in velocity iterations and can improve the efficiency of velocity modeling.

[0023] (2) The method for while-drilling seismic velocity modeling provided by the embodiment of the present invention establishes a work area according to the while-drilling processing range of the well being drilled, determines the wells drilled within the work area, and extracts the ground seismic velocity body within the work area; the well being drilled is also regarded as a well being drilled, and the above steps are used to establish a fused ground seismic velocity body within the work area. It is possible to quickly and accurately establish a fused ground seismic velocity body within the while-drilling processing range of the well being drilled, thereby providing a data basis for predicting underground information of the well being drilled and the surrounding area, making it possible to more accurately locate the target point of the well being drilled and optimize its target trajectory. At the same time, the improvement in the efficiency of velocity modeling greatly shortens the time for while-drilling processing, thereby saving the time and cost of waiting for drilling during the drilling process.

[0024] (3) The while-drilling seismic velocity modeling method provided by the embodiment of the present invention can adopt simplified while-drilling VSP seismic guidance while drilling, while meeting the requirements of timeliness and accuracy. Compared with the technology of real-time VSP acquisition while drilling, the VSP data acquisition cost is reduced.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 This is a flow chart of the velocity modeling method for fusing well-seismic information in Example 1 of the present invention;

[0028] Figure 2 A schematic diagram of seismic velocity modeling while drilling in the second embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the time-depth calibration and various curves of the well layer in the second embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the structure of the well-seismic information fusion velocity modeling device in an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the structure of the while-drilling seismic velocity modeling device in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0035] In the description of the present invention, it should be noted that the terms "including," "comprising," "having," and "containing" are open-ended terms, meaning inclusion but not limitation. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

[0036] To address the issues of time-consuming and low-precision seismic velocity modeling in VSP seismic steering while drilling (VSP) in the prior art, embodiments of the present invention provide well-seismic information fusion velocity modeling and a method and apparatus for while-drilling seismic velocity modeling, which can improve the efficiency and accuracy of seismic velocity modeling.

[0037] Example 1

[0038] The first embodiment of the present invention provides a method for velocity modeling by fusing well-seismic information, the process of which is as follows: Figure 1 As shown, the process includes the following steps S11 to S16.

[0039] There are generally three types of information that can be obtained at the well point that is directional to seismic velocity:

[0040] (1) The depth information of the layer, combined with the seismic imaging position in the time domain, can determine the average velocity within the layer;

[0041] (2) VSP logging velocity information can provide seismic velocity information propagating along the wellbore (generally vertically);

[0042] (3) Ground seismic information, which can provide ground seismic velocity information propagating along the incident angle.

[0043] This embodiment fuses the three types of velocity information using VSP logging information (VSP logging velocity curves) as a primary source, surface seismic information (surface seismic velocity volumes) as a supplement, and stratigraphic information (well layer data) as a constraint. The specific implementation process includes a wellpoint location velocity fusion step for each drilled well, as shown in steps S11 to S15; and a seismic velocity modeling step, which fuses the velocities in the three-dimensional space surrounding the well (generally within a radius of 3 kilometers), as shown in step S16.

[0044] Step S11: for each drilled well, determine a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume.

[0045] Specifically, the method may include resampling the VSP logging velocity curve according to the sampling rules of the surface seismic velocity body; and calculating, for each sampling point in the resampled VSP logging velocity curve, the difference between the VSP logging velocity and the surface seismic velocity at the sampling point, to obtain a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity body.

[0046] It can be calculated using formula (1):

[0047] ΔV i =Vw i -Vs i (1)

[0048] In formula (1), i represents the number of the sampling point in the VSP logging velocity curve, Vw i Indicates the VSP logging velocity value at the i-th sampling point, Vs i represents the ground seismic velocity value at the i-th sampling point, ΔV i It represents the difference between the VSP logging velocity value and the surface seismic velocity value at the i-th sampling point.

[0049] The calculation range is from the surface to the bottom of the well. For the sections where VSP logging data are missing, the velocity difference is assigned to zero.

[0050] Furthermore, the VSP logging velocity curve refers to a seismic wave propagation velocity curve obtained by VSP logging. In this embodiment, the description is simplified in some places, and the seismic wave propagation velocity is simplified to velocity or seismic velocity.

[0051] Step S12: Determine the control node corresponding to each layer according to the layer data of the well.

[0052] Specifically, it may include determining the point closest to each layer and whose seismic layer boundary meets the set conditions based on the well layer data, and determining the sampling point closest to the point in the VSP logging velocity curve as the control node corresponding to the layer.

[0053] The stratification standards of well logging and seismic are often inconsistent. In addition, there are errors in the depth and time domains between well logging and seismic data. Therefore, the control node is generally not directly determined based on the depth value of the layer in the stratification data and the time-depth correction results. Instead, the point closest to the layer and with a clear seismic stratification boundary is first determined. Then, based on the distribution of sampling points in the VSP logging velocity curve, the sampling point that best matches the layer is determined as the control node.

[0054] Step S13: Determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data.

[0055] Specifically, it may include obtaining the two-way travel time of the seismic wave of each control node according to the well-seismic calibration result, and determining the average velocity between two adjacent control nodes according to formula (2):

[0056]

[0057] In formula (2), V ave (k) represents the average speed of the sampling points between the kth control node and the k-1th control node, x k Indicates the depth value of the kth control node, x k-1 Indicates the depth value of the k-1th control node, t k represents the two-way travel time of the seismic wave at the kth control node, t k-1 represents the two-way travel time of the seismic wave at the k-1th control node.

[0058] Step S14: Taking the average speed as a constraint, the speed difference curve is smoothed by cubic spline function curve simulation to obtain a smooth speed difference curve.

[0059] The velocity difference curve is simulated by cubic spline function to eliminate outliers and meet the smoothness requirement of prestack depth migration. The average velocity within the layer is used as a constraint during the simulation process.

[0060] Here, the velocity error is regarded as a function that varies with depth, and a cubic spline function S(x) is constructed to satisfy:

[0061] (1) At the control node x corresponding to the layer k At S(x k )=ΔV(x k );

[0062] (2) In each stratigraphic interval [x k-1 ,x k ], S(x) is a cubic polynomial;

[0063] (3) S(x) has a continuous second-order derivative;

[0064] (IV) In each stratigraphic interval [x k-1 ,x k ], with the average velocity within the layer as the constraint, specifically satisfying the following formula (3):

[0065]

[0066] In formula (3), S(x J ) indicates that the depth value of the velocity difference curve between the kth and k-1th control nodes is x J The smoothed speed difference of sampling point J, J = 1, 2, ... N, N represents the number of sampling points of the speed difference curve between the kth and k-1th control nodes; Vs (x J ) indicates that the depth value of the velocity difference curve between the kth and k-1th control nodes is x J Planar seismic velocity of sampling point J.

[0067] According to the properties of the cubic spline function, the expression of S(x) is derived as the following formula (4). The speed difference curve between two adjacent control nodes is simulated by the cubic spline function curve using formula (4) to obtain a smooth speed difference curve:

[0068]

[0069] In formula (4), x represents the depth value of the sampling point between the kth and k-1th control nodes of the velocity difference curve; S(x) represents the smoothed velocity difference of the sampling point with a depth value of x, and S(x) is a cubic polynomial; M k represents the value of the second-order derivative of S(x) at the kth control node; M k-1 represents the value of the second-order derivative of S(x) at the k-1th control node; ΔV k represents the difference between the VSP logging velocity and the surface seismic velocity at the kth control node; ΔV k-1 It represents the difference between the VSP logging velocity and the surface seismic velocity at the k-1th control node.

[0070] According to the natural boundary conditions, that is, the natural conditions for smooth transition between layers and the constraints of formula (3), the appropriate M can be obtained. k The velocity error at each sampling point is obtained by calculating the value. At this time, the velocity error is a smooth curve from the surface to the bottom of the well.

[0071] Step S15: Obtain a fused velocity curve from the smoothed velocity difference curve and the ground seismic velocity volume.

[0072] By adding the obtained smoothed velocity error curve to the surface seismic velocity from the surface to the bottom of the well, a more accurate single-point velocity curve at the well point can be obtained, which integrates drilling information, mud logging information, VSP logging information and surface seismic information, namely the fused velocity curve.

[0073] For all the drilled wells in the space around the well, the above method can be used to obtain the precise well point position velocity from the surface to the bottom of the well after information fusion, that is, the fused velocity curve.

[0074] Step S16: Using the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints, a velocity model is established by using the co-kriging interpolation method to obtain a fused surface seismic velocity volume.

[0075] In the three-dimensional space surrounding the well, the fused surface seismic velocities are correlated with the original surface seismic velocities. Combining the fused wellpoint velocities with the surface seismic velocities and re-integrating them using co-kriging interpolation technology yields a 3D velocity volume around the well. This is typically calculated layer by layer, with the two velocity models processed at depth within the same formation to enhance spatial velocity correlation.

[0076] Specifically, it may include, for each transverse sampling plane in the ground seismic velocity volume, using formula (5) to obtain the fused ground seismic velocity of the sampling points in the plane:

[0077]

[0078] In formula (5), V * (x) represents the fused ground seismic velocity at the sampling point with depth x in the plane; V1(x i ) represents the fusion velocity (main variable) of sampling point i at depth x in the fusion velocity curve of the drilled well, i = 1, 2, ... n, n represents the number of drilled wells; A 1i V1(x i ) weighting coefficient; V2(x j ) is the ground plane seismic velocity (covariate) of sampling point j in the plane that does not correspond to the drilled well, j = 1, 2, ... m, m represents the number of sampling points in the plane except the sampling points corresponding to the drilled well; B 2j V2(x j ) weighting coefficient.

[0079] Introduce two Lagrange multipliers u1 and u2, establish a Kriging matrix based on the unbiasedness and least squares method of the Kriging method, and obtain A through the Kriging matrix 1i 、B 2j , u1 and u2; the obtained A 1i 、B 2j Substitute into the formula (5) to calculate V * (x), the fused ground seismic velocity volume is obtained, and the Kriging matrix is ​​the following formula (6):

[0080]

[0081] In formula (6), V1(x k1 ) represents the fusion velocity of the sampling point k1 at depth x in the fusion velocity curve of the drilled well; V2(x k1 ) represents the ground seismic velocity at sampling point k1; V2(x k2 ) represents the surface seismic velocity of the sampling point k2 corresponding to the non-drilled well in the plane.

[0082] The first embodiment of the present invention provides a velocity modeling method for fusing well-seismic information. The wellpoint location velocity fusion step includes determining a velocity difference curve between the VSP well logging velocity curve and the surface seismic velocity volume for each drilled well; determining the control node corresponding to each layer based on the well's stratified data; determining the average velocity between two adjacent control nodes based on the well-seismic calibration results and the well's stratified data; smoothing the velocity difference curve using a cubic spline function curve simulation with the average velocity as a constraint; and obtaining a fused velocity curve from the smoothed velocity difference curve and the seismic velocity volume. The seismic velocity modeling step includes establishing a velocity model using a co-kriging interpolation method with the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints to obtain a fused surface seismic velocity volume. Using mathematical algorithms such as cubic spline function simulation and co-kriging interpolation, the drilling information, VSP well logging information, and existing surface seismic velocity volume information are efficiently and accurately fused, so that the determined fused velocity vertical trend is consistent with the well information and the lateral variation trend is consistent with the surface seismic velocity volume, thereby improving the accuracy of the velocity modeling. At the same time, using mathematical calculations instead of velocity iterations reduces the time consumed in velocity iterations and can improve the efficiency of velocity modeling.

[0083] Example 2

[0084] The second embodiment of the present invention provides a method for seismic velocity modeling while drilling, which is an efficient velocity modeling method that uses mathematical algorithms to fuse multiple information such as ground seismic information, drilling information, and logging information. It belongs to the field of oil and gas exploration and is a method for processing and interpreting seismic data in real time during the drilling process. It is suitable for the seismic guidance processing stage of oil geophysical exploration while drilling. The process is as follows: Figure 2 As shown, the following steps are included:

[0085] Step S21: establishing a work area according to the while-drilling processing range of the well being drilled, determining the drilled wells in the work area, and extracting the surface seismic velocity volume in the work area.

[0086] Determine the scope of the LWD processing based on the geological structure changes around the well and establish the work area. Load drilling information, mud logging information, VSP logging information, and information on adjacent wells within the scope. Determine geological layers and logging velocities based on the well information. Load prestack depth migration velocity information within the LWD processing scope.

[0087] The information of the drilling well or the drilled well obtained after loading includes: VSP logging velocity curve, well layer data and well-seismic calibration results; seismic data includes pre-stack depth migration surface seismic velocity volume in the work area.

[0088] Step S22: for the well being drilled and each drilled well, determine a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume.

[0089] Step S23: Determine the control node corresponding to each layer according to the layer data of the well.

[0090] Step S24: Determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data.

[0091] Step S25: Taking the average speed as a constraint, the speed difference curve is smoothed by cubic spline function curve simulation to obtain a smooth speed difference curve.

[0092] Step S26: Obtain a fused velocity curve from the smoothed velocity difference curve and the ground seismic velocity volume.

[0093] Step S27: Using the surface seismic velocity volume and the fused velocity curves of the well being drilled and each drilled well as constraints, a velocity model is established by using the co-kriging interpolation method to obtain a fused surface seismic velocity volume.

[0094] For details of the above steps that are the same or similar to those in Example 1, please refer to Example 1 and will not be repeated here.

[0095] The method for while-drilling seismic velocity modeling provided in the second embodiment of the present invention establishes a work area based on the while-drilling processing range of the well being drilled, determines the wells already drilled within the work area, and extracts the ground seismic velocity volume within the work area. The well being drilled is also considered as a drilled well, and the above steps are used to establish a fused ground seismic velocity volume within the work area. It is possible to quickly and accurately establish a fused ground seismic velocity volume within the while-drilling processing range of the well being drilled, thereby providing a data basis for predicting underground information in the well being drilled and the surrounding area, making it possible to more accurately locate the target point of the well being drilled and optimize its target trajectory. At the same time, the improvement in velocity modeling efficiency greatly shortens the time for while-drilling processing, thereby saving the time and cost of waiting for drilling during the drilling process.

[0096] The method for seismic velocity modeling while drilling provided in the second embodiment of the present invention can adopt simplified VSP seismic guidance while drilling while meeting the requirements of timeliness and accuracy. VSP data are collected during each cementing stage. Compared with the technology of real-time VSP data collection while drilling, the cost of VSP data collection is reduced.

[0097] In order to make the technical solution of the present invention clearer, the technical solution in the embodiment of the present invention will be described clearly and in detail in combination with specific application examples. The seismic data in the example comes from an oil field block A in western China. According to the interpretation results of the ground seismic processing results completed in 2019, a risk well M1 was drilled in this area in 2020. During the drilling process, it was found that the actual layer position differed from the predicted layer position by 120 meters. It was difficult to drill into the established target reservoir based on the original drilling trajectory. Therefore, when the fourth well was completed, VSP logging was performed on the well, and the drilling was stopped on site to wait for new seismic processing and interpretation results, and a new drilling trajectory adjustment plan was formulated. According to the existing processing technology, even if the processing is expedited, the reprocessing of the seismic data is estimated to be more than ten days, and the drilling stop time is estimated to be more than half a month, which will bring huge economic losses. However, the application of the downhole seismic velocity modeling method of the present invention can compress the processing time to 68 hours and the drilling stop time to 5 days, saving a lot of time, manpower and material costs. In the end, the well was successfully drilled into the reservoir and the oil test was high-yielding.

[0098] This example is implemented in the following steps:

[0099] 1. This work area is located in a desert area, where the shallow strata have little lateral variation and the velocity has a strong correlation. A new work area of ​​36 square kilometers around the M1 well was selected from the original work area.

[0100] 2. Well M1 is a risk exploration well. The distance between the adjacent wells and this well is about 7 kilometers, so its reference value is not great. Only the VSP logging velocity curve, geological stratification and corridor overlay data of Well M1 are loaded.

[0101] 3. Load the ground seismic velocity volume within 36 square kilometers. Since no well-seismic calibration was done in advance, the pre-stack depth migration results in the time domain and depth domain were also loaded.

[0102] 4. Perform well-seismic calibration on geological layers to obtain the control nodes corresponding to each layer and the average velocity within each layer.

[0103] 5. Extract the well point seismic velocity, resample the VSP logging velocity to be consistent with the surface seismic velocity, and calculate the velocity error between the surface seismic velocity and the VSP logging velocity.

[0104] 6. Calculate the average value of the sampling points near each layer, and select the error value point closest to the average value as the simulation node of the spline function curve.

[0105] 7. For the velocity error obtained in step 5, perform a cubic sample function curve simulation according to the nodes in step 6 to obtain a cubic spline velocity error curve. During the simulation process, the average velocity in step 4 is used as a constraint.

[0106] 8. Add the velocity error curve obtained in step 7 to the surface seismic velocity to obtain the fused velocity curve at the well point.

[0107] Specifically, the VSP logging velocity curve, the surface seismic velocity curve at the well trajectory, the geological layering, the well-seismic error curve (the velocity error curve between the surface seismic velocity and the VSP logging velocity) and the spline function (the cubic spline velocity error curve) in the above steps, as well as the control nodes are shown in FIG. Figure 3 shown.

[0108] 10. Pick up the seismic layers according to the seismic profile event axis corresponding to the geological layers and establish a spatial structural model.

[0109] 11. Use the obtained fusion velocity curve at the well point and the surface seismic velocity to establish the co-kriging variance matrix.

[0110] 12. Using the model correlation as a constraint, solve the covariance matrix obtained in step 11, calculate the grid points of each formation layer by layer, obtain the velocity of each grid point, and form a three-dimensional spatial velocity field around the well.

[0111] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a well-seismic information fusion velocity modeling device, the structure of which is as follows: Figure 4 Shown, including:

[0112] The well point location velocity fusion module 41 is used to determine, for each drilled well, a velocity difference curve between a VSP logging velocity curve and a surface seismic velocity volume; determine a control node corresponding to each layer based on the well's layered data; determine an average velocity between two adjacent control nodes based on the well-seismic calibration results and the well's layered data; smooth the velocity difference curve using a cubic spline function curve simulation with the average velocity as a constraint to obtain a smoothed velocity difference curve; and obtain a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume.

[0113] The seismic velocity modeling module 42 is configured to establish a velocity model by using the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity volume.

[0114] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a while drilling seismic velocity modeling device, the structure of which is as follows: Figure 5 Shown, including:

[0115] A work area establishment module 51 is used to establish a work area according to the drilling while drilling processing range of the well being drilled, determine the drilled wells in the work area, and extract the surface seismic velocity volume in the work area;

[0116] The well point location velocity fusion module 52 is used to determine, for each well being drilled and each drilled well, a velocity difference curve between a VSP logging velocity curve and a surface seismic velocity volume; determine a control node corresponding to each layer based on the well's layered data; determine an average velocity between two adjacent control nodes based on the well seismic calibration results and the well's layered data; smooth the velocity difference curve using a cubic spline function curve simulation with the average velocity as a constraint to obtain a smoothed velocity difference curve; and obtain a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume.

[0117] The seismic velocity modeling module 53 is configured to establish a velocity model by using the surface seismic velocity volume and the fused velocity curves of the well being drilled and each drilled well as constraints to obtain a fused surface seismic velocity volume.

[0118] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0119] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a computer program product with seismic velocity modeling function, including a computer program / instruction, wherein when the computer program / instruction is executed by a processor, the above-mentioned well-seismic information fusion velocity modeling method or the above-mentioned while-drilling seismic velocity modeling method is implemented.

[0120] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0121] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are therefore hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0122] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purposes of describing the above embodiments, but one of ordinary skill in the art will recognize that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to encompass all such changes, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent the term "comprising" is used in the specification or claims, the term is intended to be encompassed in a manner similar to the term "including," as explained in terms of "including," used as a transitional word in the claims. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or."

Claims

1. A velocity modeling method based on well-seismic information fusion, characterized in that: include: Well point location velocity fusion step: for each drilled well, determine the velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume; Determine the point closest to each layer and whose seismic layer boundary meets the set conditions based on the well layer data, and determine the sampling point closest to the point in the VSP logging velocity curve as the control node corresponding to the layer; determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtain a fused velocity curve by combining the smoothed velocity difference curve with the surface seismic velocity volume; The seismic velocity modeling step is to establish a velocity model by using the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity volume.

2. The method according to claim 1, wherein Determining the velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume specifically includes: The VSP logging velocity curve is resampled according to the sampling rules of the surface seismic velocity body; For each sampling point in the resampled VSP logging velocity curve, the difference between the VSP logging velocity and the surface seismic velocity at the sampling point is calculated to obtain a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume.

3. The method according to claim 1, wherein Determining the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data specifically includes: The two-way travel time of seismic waves at each control node is obtained based on the well-seismic calibration results, and the average velocity between two adjacent control nodes is determined according to formula (1): In formula (1), V ave (k) represents the average speed of the sampling points between the kth control node and the k-1th control node, x k Indicates the depth value of the kth control node, x k-1 Indicates the depth value of the k-1th control node, t k represents the two-way travel time of the seismic wave at the kth control node, t k-1 represents the two-way travel time of the seismic wave at the k-1th control node.

4. The method according to claim 3, wherein The smoothing process of the speed difference curve by simulating a cubic spline function curve to obtain a smooth speed difference curve specifically includes: The speed difference curve between two adjacent control nodes is simulated by cubic spline function curve using formula (2) to obtain a smooth speed difference curve: In formula (2), x represents the depth value of a sampling point between the kth and k-1th control nodes of the speed difference curve; S(x) represents the smoothed speed difference of the sampling point with a depth value of x, and S(x) is a cubic polynomial; M k represents the value of the second-order derivative of S(x) at the kth control node; M k-1 represents the value of the second-order derivative of S(x) at the k-1th control node; ΔV k represents the difference between the VSP logging velocity and the surface seismic velocity at the kth control node; ΔV k-1 It represents the difference between the VSP logging velocity and the surface seismic velocity at the k-1th control node.

5. The method according to claim 4, wherein The average speed is used as a constraint, specifically including formula (3) as a constraint condition: In formula (3), S(x J ) indicates that the depth value of the velocity difference curve between the kth and k-1th control nodes is x J The smoothed speed difference of sampling point J, J = 1, 2, ... N, N represents the number of sampling points of the speed difference curve between the kth and k-1th control nodes; Vs (x J ) represents the plane seismic velocity of sampling point J.

6. The method according to claim 1, wherein The method of establishing a velocity model by using the surface seismic velocity volume and the fused velocity curve of at least one drilled well as constraints to obtain a fused surface seismic velocity volume by using a co-kriging interpolation method specifically includes: For each transverse sampling plane in the surface seismic velocity volume, the fused surface seismic velocity of the sampling points in the plane is obtained using formula (4): In formula (4), V * (x) represents the fused ground seismic velocity at the sampling point with depth x in the plane; V1(x i ) represents the fusion velocity of sampling point i at depth x in the fusion velocity curve of the drilled well, i = 1, 2, ... n, n represents the number of drilled wells; A 1i V1(x i ) weighting coefficient; V2(x j ) is the ground plane seismic velocity of the sampling point j in the plane that does not correspond to the drilled well, j = 1, 2, ... m, m represents the number of sampling points in the plane except the sampling points corresponding to the drilled well; B 2j V2(x j ) weighting coefficient; Introduce two Lagrange multipliers u1 and u2, establish a Kriging matrix based on the unbiasedness and least squares method of the Kriging method, and obtain A through the Kriging matrix 1i 、B 2j , u1 and u2; the obtained A 1i 、B 2j Substitute into the formula (4) to calculate V * (x), and the fused ground seismic velocity volume is obtained. The Kriging matrix is ​​the following formula (5): In formula (5), V1(x k1 ) represents the fusion velocity of the sampling point k1 at depth x in the fusion velocity curve of the drilled well, k1=1,2……,n; V2(x k1 ) represents the ground seismic velocity at sampling point k1; V2(x k2 ) represents the surface seismic velocity of the sampling point k2 corresponding to the non-drilled well in the plane, k2 = 1, 2..., m.

7. A method for seismic velocity modeling while drilling, characterized in that: include: A work area establishment step, establishing a work area according to a while-drilling processing range of the well being drilled, determining the drilled wells within the work area, and extracting a surface seismic velocity volume within the work area; The well point location velocity fusion step includes determining a velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume for each well being drilled and each well already drilled; determining the point closest to each layer and having a seismic layer boundary that meets set conditions based on the well's layered data, and determining the sampling point closest to the point in the VSP logging velocity curve as the control node corresponding to the layer; determining the average velocity between two adjacent control nodes based on the well-seismic calibration results and the well's layered data; using the average velocity as a constraint, smoothing the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtaining a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume; The seismic velocity modeling step is to establish a velocity model by using the surface seismic velocity body and the fused velocity curves of the well being drilled and each drilled well as constraints, thereby obtaining a fused surface seismic velocity body.

8. A velocity modeling device for fusion of well and seismic information, characterized in that: include: Well point location velocity fusion module, used to determine the velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume for each drilled well; Determine the point closest to each layer and whose seismic layer boundary meets the set conditions based on the well layer data, and determine the sampling point closest to the point in the VSP logging velocity curve as the control node corresponding to the layer; determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtain a fused velocity curve by combining the smoothed velocity difference curve with the surface seismic velocity volume; The seismic velocity modeling module is used to establish a velocity model by using the surface seismic velocity body and the fused velocity curve of at least one drilled well as constraints, thereby obtaining a fused surface seismic velocity body.

9. A while-drilling seismic velocity modeling device, characterized in that: include: A work area establishment module is used to establish a work area according to the drilling while drilling processing range of the well being drilled, determine the drilled wells in the work area, and extract the surface seismic velocity volume in the work area; The well point location velocity fusion module is used to determine the velocity difference curve between the VSP logging velocity curve and the surface seismic velocity volume for each well being drilled and each drilled well; determine the point closest to each layer and whose seismic layer boundary meets the set conditions based on the well layer data, and determine the sampling point closest to the point in the VSP logging velocity curve as the control node corresponding to the layer; determine the average velocity between two adjacent control nodes based on the well seismic calibration results and the well layer data; use the average velocity as a constraint to smooth the velocity difference curve through cubic spline function curve simulation to obtain a smoothed velocity difference curve; and obtain a fused velocity curve from the smoothed velocity difference curve and the surface seismic velocity volume; The seismic velocity modeling module is used to establish a velocity model by using the surface seismic velocity body and the fused velocity curves of the drilling well and each drilled well as constraints to obtain a fused surface seismic velocity body through the co-kriging interpolation method.

10. A computer program product having seismic velocity modeling functionality, comprising a computer program / instructions, wherein: When the computer program / instruction is executed by a processor, the well-seismic information fusion velocity modeling method according to any one of claims 1 to 6 is implemented, or the while-drilling seismic velocity modeling method according to claim 7 is implemented.

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