A method and device for determining anisotropy parameters

Abstract

The present invention discloses a method and device for determining anisotropic parameters. The method includes obtaining a thickness error threshold, a velocity error threshold, and the well calibration thickness, isotropic thickness, logging velocity, and isotropic velocity of each layer; for each layer, determining a thickness error enumeration value based on the thickness error threshold, and determining an anisotropic parameter enumeration value based on the thickness error enumeration value, the well calibration thickness, and isotropic thickness of the layer; determining a velocity error based on the anisotropic parameter enumeration value, the logging velocity, and the isotropic velocity, and screening valid anisotropic parameter enumeration values ​​whose velocity errors meet the velocity error threshold; determining a total score of valid enumeration values ​​based on a velocity weight value, a thickness weight value, and the velocity error and thickness error enumeration values ​​corresponding to the valid enumeration values; and screening the optimal anisotropic parameter value based on the total score. The method can use the thickness error threshold and the velocity error threshold as constraints to determine more reasonable anisotropic parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas geological exploration seismic data processing and interpretation, and in particular to a method and device for determining anisotropy parameters. Background Art

[0002] The geological horizons obtained from isotropic pre-stack depth migration often have large depth errors compared to actual logging and drilling results, making them difficult to use directly for subsequent interpretation and structural mapping. As the accuracy requirements and application level of pre-stack depth migration technology increase, anisotropic depth migration has replaced isotropic depth migration and gradually become the mainstream depth migration application in the industry. The reason why isotropic depth migration produces large depth errors is that it does not take into account the velocity anisotropy of the underground medium. Velocity anisotropy refers to the different instantaneous velocities of seismic waves at each location in the medium when propagating along different paths in different directions. Seismic data collected in the field generally collect seismic waves along different paths at a certain location underground. If pre-stack depth migration based on the isotropic assumption is used, large depth errors will be generated.

[0003] Thomsen (1986) proposed parameters to characterize the elastic properties of anisotropic media. Delta (δ) is the coefficient of variation of the P-wave, which physically represents the second-order derivative of the P-wave phase velocity with respect to the phase angle near zero. It indicates the degree of anisotropic variation of the P-wave in the vertical direction. As a key parameter in anisotropic migration, its calculation accuracy directly affects the error of prestack depth migration. In anisotropic prestack depth migration of VTI and TTI media, Delta is not only a key parameter in anisotropic migration but also a key parameter for determining anisotropic velocity. The accuracy of Delta calculation directly affects the wellbore seismic depth error of actual seismic data and drilling and logging data. The more accurately the anisotropic Delta parameter is calculated, the higher the fidelity of the anisotropic migration results.

[0004] Typically, the anisotropy parameter Delta can be calculated using the following three methods. The first method involves measuring rock samples in the laboratory, which allows for accurate calculation of the anisotropy parameter. This method is straightforward, reliable, and highly accurate. However, its disadvantages are the difficulty in collecting rock samples and simulating the high-temperature, high-pressure underground environment, making it difficult to apply. The second method uses variable-offset Walk-away VSP data, picking initial waves from common-shot and common-receiver gathers and estimating the anisotropy parameter through curve fitting. However, this method is relatively expensive and requires a limited number of wells, making it difficult to apply. The third method involves indirect calculation using seismic, logging, and drilling data through well-seismic formation thickness comparison.

[0005] The third method for obtaining the Delta field is currently widely used in the industry. However, this algorithm is a single-parameter constraint algorithm. It uses the thickness of the formation as input without considering the velocity of the wellbore seismic data, and only uses the difference in wellbore seismic velocity as a means of quality control. This single-parameter constraint method has significant limitations. It requires high accuracy in well logging and drilling stratification. In practice, statistical errors in wellbore seismic thickness are often unavoidable. In practical applications, fine-tuning is usually performed based on experience to further reduce the wellbore seismic errors. The resulting Delta field often introduces large errors, seriously affecting the accuracy of anisotropic prestack depth migration. Summary of the Invention

[0006] The commonly used method for obtaining the Delta field in existing technologies is to indirectly calculate the formation thickness by comparing seismic, well logging, and drilling data. This method is a single-parameter constraint method that uses the formation thickness calibrated by well logging as a constraint condition. The implementation process and quality control method of this algorithm are as follows:

[0007] For the main geological strata of each well in the study area, the Delta (δ) value of each well point position is first calculated based on the well-seismic thickness relationship of the stratum. The calculation formula using the well-seismic thickness single parameter constraint (maximum thickness error constraint) is:

[0008]

[0009] In formula (1), H1 is the thickness of the isotropic depth migration section in the layer, that is, the isotropic thickness; H0 is the thickness of the layer recorded by the actual well logging and drilling log calibration, that is, the well calibration thickness, which can be regarded as the true layer thickness considering the anisotropy effect; δ is the anisotropy parameter Delta.

[0010] In practical applications, it is necessary to strengthen the quality control of the Delta calculated by single parameter constraint. Generally, the corresponding anisotropic velocity and logging velocity are compared. If the difference is not large, the Delta is considered reasonable; if the difference is large, the Delta is considered unreliable and the basic data needs to be reviewed or modified with the interpretation personnel. The principle of the quality control method is as follows:

[0011] The δ value calculated by the above formula is used as the average velocity or reference velocity of the isotropic depth migration profile in the layer system, that is, the isotropic velocity is used as input to calculate the corresponding anisotropic velocity. The calculation formula is:

[0012]

[0013] In formula (2), V I is the isotropic velocity within the layer; V A is the calculated anisotropic velocity.

[0014] Ideally, the calculated anisotropic velocity is equal to the corresponding logging velocity (average velocity or reference velocity) in the layer. The velocity error calculated by subtracting the calculated anisotropic velocity from the corresponding logging velocity in the layer is conceptually the anisotropic velocity error, which is expressed as follows:

[0015] ΔV=V A -V0 (3)

[0016] In formula (3), V0 is the logging velocity within the layer; ΔV is the anisotropic velocity error.

[0017] The above algorithm takes the thickness of the wellbore seismic data as input, without considering the velocity of the wellbore seismic data. It only uses the difference in wellbore seismic velocity as a means of quality control. In order to distinguish it from the method introduced in this invention, the above method is called a single parameter constraint method.

[0018] However, the single-parameter constraint method has significant limitations. It requires high precision in both well logging and seismic layering. In practice, errors in well-seismic thickness statistics primarily arise from three sources: ① incorrect well logging or drilling layer calibration; ② incorrect seismic profile calibration; and ③ acceptable systematic errors, such as resolution issues in the calibration comparison between VSP layers and seismic profiles. For issue ①, the solution is to avoid using the calibration data from this well. Using erroneous information from this well can sometimes produce spurious geological structures during prestack depth migration. For issue ②, the solution is to strengthen the integration of processing and interpretation personnel, recalibrating seismic profiles using methods such as well-seismic synthetic record calibration. For issue ③, there is currently no reliable solution in the industry. Single-parameter constraint algorithms are typically used, and in practice, fine-tuning is performed based on experience to further reduce well-seismic errors. The resulting δ field often results in significant errors, seriously impacting the accuracy of anisotropic prestack depth migration.

[0019] Currently, most exploration targets are thin reservoirs, and the exploration accuracy requirements are getting higher and higher. Based on the δ field calculated based on single-parameter constraints, a small error will also lead to a large anisotropic velocity error, affecting the accuracy of anisotropic prestack depth migration.

[0020] In view of the above problems, the present invention is proposed to provide a method and device for determining anisotropic parameters that overcome the above problems or at least partially solve the above problems. The method and device can use the thickness error threshold and the velocity error threshold as constraints to determine more reasonable anisotropic parameters.

[0021] In a first aspect, an embodiment of the present invention provides a method for determining anisotropy parameters, comprising:

[0022] Data acquisition step, obtaining thickness error threshold, velocity error threshold and well calibration thickness, isotropic thickness, logging velocity and isotropic velocity of each layer;

[0023] The following steps for determining anisotropy parameters are performed for each layer system:

[0024] Determining a plurality of thickness error enumeration values ​​according to the thickness error threshold, and determining a corresponding anisotropic parameter enumeration value according to each thickness error enumeration value, the well calibration thickness and the isotropic thickness of the layer system;

[0025] Determine the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity and the isotropic velocity of the layer system, and select the anisotropic parameter enumeration value whose velocity error meets the velocity error threshold as the valid anisotropic parameter enumeration value;

[0026] Determine the total score of the effective enumeration value of the anisotropic parameter according to the set velocity weight value, the set thickness weight value, and the velocity error and thickness error enumeration values ​​corresponding to the effective enumeration value of the anisotropic parameter;

[0027] The valid enumeration value of the anisotropy parameter with the highest total score is determined as the optimal value of the anisotropy parameter of the layer system.

[0028] In a second aspect, an embodiment of the present invention provides an anisotropy parameter determination device, comprising:

[0029] Data acquisition module, used to obtain thickness error threshold, velocity error threshold and well calibration thickness, isotropic thickness, logging velocity and isotropic velocity of each layer;

[0030] The anisotropic parameter determination module is used to perform the following anisotropic parameter determination steps for each layer system: determining multiple thickness error enumeration values ​​according to the thickness error threshold value, determining the corresponding anisotropic parameter enumeration value according to each thickness error enumeration value, the well calibration thickness and isotropic thickness of the layer system; determining the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity and isotropic velocity of the layer system, screening the anisotropic parameter enumeration values ​​whose velocity errors meet the velocity error threshold value as the effective anisotropic parameter enumeration values; determining the total score of the effective anisotropic parameter enumeration values ​​according to the set velocity weight value, the set thickness weight value, and the velocity error and thickness error enumeration values ​​corresponding to the effective anisotropic parameter enumeration values; and determining the effective anisotropic parameter enumeration value with the highest total score as the optimal anisotropic parameter value of the layer system.

[0031] In a third aspect, an embodiment of the present invention provides a computer program product having an anisotropy parameter calculation function, including a computer program / instruction, wherein the computer program / instruction implements the above-mentioned anisotropy parameter determination method when executed by a processor.

[0032] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0033] (1) The anisotropic parameter determination method provided in an embodiment of the present invention determines, for each layer, multiple thickness error enumeration values ​​based on a thickness error threshold, and determines the corresponding anisotropic parameter enumeration value based on each thickness error enumeration value, the well calibration thickness of the layer, and the isotropic thickness; determines the corresponding velocity error based on the anisotropic parameter enumeration value, the well logging velocity, and the isotropic velocity of the layer, and selects the anisotropic parameter enumeration values ​​whose velocity errors meet the velocity error threshold as valid anisotropic parameter enumeration values. This method uses well stratification and actual seismic stratification information to obtain the thickness error threshold constraint Delta value of the layer; and uses well logging velocity and seismic velocity information to obtain the velocity error threshold constraint Delta value of the layer. An innovative method for obtaining anisotropic Delta parameters was developed through the dual-parameter constraints of thickness error threshold and velocity error threshold. This effectively avoids the defects of the industry's commonly used method of obtaining layer thickness through well stratification calibration and single-parameter Delta calculation, such as anisotropic Delta errors caused by well stratification errors or incorrect well stratification. The selected valid enumeration values ​​of the anisotropic parameters meet both the thickness error threshold and the velocity error threshold. Then, based on the set velocity weight value, the set thickness weight value, and the velocity error and thickness error enumeration values ​​corresponding to the valid enumeration values ​​of the anisotropic parameters, the total score of the valid enumeration values ​​of the anisotropic parameters is determined. The valid enumeration value with the highest total score is determined as the optimal value of the anisotropic parameter for the layer system, further ensuring the rationality of the Delta value.

[0034] (2) In the actual seismic exploration area, the double-parameter constrained anisotropic Delta parameter calculation is performed for all well points in the work area. At the same time, the errors in the calculation of the anisotropic parameter Delta caused by the wrong well stratification can be identified. The Delta values ​​with large errors or errors obtained by the single-parameter constraint can be corrected or deleted to obtain more accurate and reasonable Delta parameters, which can better avoid the occurrence of underground false geological structures and reduce the risks of well deployment and drilling.

[0035] (3) The optimal value of anisotropic parameters is determined by calculation through well-seismic layering data, logging velocity, and isotropic seismic velocity, which is highly efficient, low-cost, and has a wide range of applications.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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:

[0038] Figure 1 is a flow chart of a method for determining anisotropy parameters in an embodiment of the present invention;

[0039] Figure 2 for Figure 1 Specific implementation flow chart of step S14;

[0040] Figure 3 Schematic diagram of the structure of an anisotropy parameter determination device in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In order to solve the problems in the prior art of the anisotropic parameter Delta calculation method having limited applicability and low accuracy of the determined Delta, an embodiment of the present invention provides a method and device for determining anisotropic parameters, which can use the dual parameters of thickness error threshold and velocity error threshold as constraints to determine more reasonable anisotropic parameters.

[0046] Example

[0047] The embodiment of the present invention provides a method for determining anisotropy parameters, the process of which is as follows: Figure 1 As shown, the process includes a data acquisition step, specifically step S11, and an anisotropic parameter determination step performed for each layer system, specifically steps S12 to S15.

[0048] Step S11: Obtain thickness error threshold, velocity error threshold, and well calibration thickness, isotropic thickness, logging velocity, and isotropic velocity of each layer.

[0049] Specifically, the determination of the stratum system may include determining the stratum between the base surface and the adjacent control horizon as one stratum system, and determining the stratum between two adjacent control horizons as one stratum system.

[0050] The datum level is usually selected from a stably developed lake flooding surface or sea flooding surface within the work area, and different study areas or different interpreters within the work area generally choose the same datum level, which can ensure the uniformity of the interpretation results standards.

[0051] The depths of the top and bottom interfaces (here, the top and bottom interfaces are the control horizons or datums) of each layer in the isotropic prestack depth migration profile are read, and their thicknesses are calculated as the isotropic thickness for solving the layer. The drilling or logging layer calibration values ​​of the top and bottom interfaces of each layer are read, and their thicknesses are calculated as the well-calibrated thickness for solving the layer. For each layer, the well logging velocity and the average velocity within the layer in the isotropic depth migration profile are read (if the well seismic velocity patterns within the layer are highly similar, the reference velocity of a point within the layer can also be read) as the well logging velocity and isotropic velocity for solving the layer. Table 1 shows an example of the well-calibrated depths, isotropic depths, and well-calibrated thicknesses, isotropic thicknesses, logging velocities, and isotropic velocities of the layers that constitute it for each control horizon and datum passing through Well A.

[0052] Table 1 Statistics of depth, thickness, velocity and single parameter anisotropy parameter Delta of Well A

[0053]

[0054] For each layer, the maximum allowable thickness error, i.e., the thickness error threshold, and the maximum allowable velocity error, i.e., the velocity error threshold, are determined based on the well-seismic error assessment indicators for the study area and the actual formation conditions. Furthermore, the thickness error threshold and velocity error threshold for each layer can be the same or different. This embodiment uses the example of a constant thickness error threshold and constant velocity error threshold for each layer.

[0055] The above step 1 is the data acquisition step, and the subsequent step is the step of obtaining the anisotropy parameter Delta (δ). The following steps S12 to S15 are performed for each layer system. They can also be performed simultaneously for each layer system during the execution of each step, and finally a reasonable Delta (δ) value is determined for each layer system.

[0056] Step S12: determining a plurality of thickness error enumeration values ​​according to the thickness error threshold, and determining a corresponding anisotropic parameter enumeration value according to each thickness error enumeration value, the well calibration thickness of the layer system, and the isotropic thickness.

[0057] Multiple thickness error enumeration values ​​are determined according to the thickness error threshold and the set step size. For example, if the thickness error threshold MaxDH=10 and the set step size is 2, the thickness error enumeration values ​​can be determined to be ±10, ±8, ±6, ±4, ±2 and 0 respectively.

[0058] First, calculate the expected thickness for anisotropic prestack depth migration as follows:

[0059]

[0060] In formula (4), H I is the isotropic thickness of the layer system; H A is the calculated anisotropic thickness.

[0061] According to formula (1), we can get:

[0062]

[0063] In formula (5), Calibrate the thickness of the calculated well.

[0064] The calculated values ​​of anisotropic thickness and well calibration thickness can be obtained from formula (4) and formula (5) respectively.

[0065] Subtract the calculated anisotropic thickness from the well calibration thickness within the layer system, and the calculated difference is the anisotropic thickness error within the layer system. The formula is as follows:

[0066] ΔH=|H A -H0| (6)

[0067] In formula (6), H0 is the well calibration thickness of the layer; ΔH is the anisotropic thickness error within the layer.

[0068] It can be seen from the above formulas (4) to (6) that when both well calibration and seismic calibration are accurate, the calculated ΔH = 0. In an ideal state, if the basic data are very accurate, the calculated anisotropic velocity is equal to the corresponding logging velocity (average velocity or reference velocity) in the layer system, that is, the anisotropic velocity error ΔV = 0; at the same time, the calculated anisotropic thickness error is 0, that is, ΔH = 0. However, in actual situations, there are generally certain errors in well calibration and logging velocity; there are also corresponding errors in seismic layer picking and calculation, and there are also layering errors in seismic layering due to the influence of seismic data resolution. Therefore, in actual applications, due to the existence of various errors, even when ΔH = 0, ΔV ≠ 0 often occurs, and ΔV may even be abnormally greater than the maximum value we give. This velocity error is often caused by problems in well-seismic calibration. When a certain thickness error range is allowed, the optimal solution that meets the velocity error condition can be found.

[0069] Within the thickness error threshold MaxDH, the enumeration method can be used to find all values ​​that satisfy |ΔH|≤MaxDH and |ΔV|≤MaxDV (MaxDV is the velocity error threshold). The solutions that meet the conditions are scored according to certain scoring criteria. The solution with the largest total score is the optimal solution for the two-parameter constraint.

[0070] For a given thickness error threshold MaxDH, let the integer variable ΔH be the thickness error. Using formula (1), we can get the corresponding Delta value when ΔH = 0. Borrowing formula (1), we can use the enumeration method to find all Delta values ​​that meet the condition |ΔH|≤MaxDH. Substituting H0 in formula (1) with H0+ΔH, we can get the calculation formula of the anisotropic parameter Delta containing the error ΔH:

[0071]

[0072] According to the thickness error enumeration value ΔH, the well calibration thickness H0 of the layer system and the isotropic thickness H1, the above formula (7) is used to determine the anisotropic parameter enumeration value δ(ΔH) corresponding to the thickness error enumeration value ΔH.

[0073] Assuming MaxDH=10, the anisotropic parameter Delta values ​​corresponding to different thickness errors ΔH of different layers are calculated using formula (7), as shown in Table 2:

[0074] Table 2 Statistics of Delta values ​​calculated for different thickness errors of various layers passing through Well A

[0075]

[0076] Step S13: determining the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity of the layer and the isotropic velocity, and screening the anisotropic parameter enumeration value whose velocity error meets the velocity error threshold as the valid anisotropic parameter enumeration value.

[0077] Specifically, according to the anisotropic parameter enumeration value δ(ΔH) and the isotropic velocity V of the layer system I , use the following formula (8) to determine the anisotropic velocity calculation value V corresponding to the thickness error enumeration value ΔH A (ΔH):

[0078]

[0079] Calculate the value V based on the anisotropic velocity A (ΔH) and the logging velocity V0 of the layer, and use the following formula (9) to determine the corresponding velocity error ΔV(ΔH):

[0080] ΔV(ΔH)=V A (ΔH)-V0 (9).

[0081] For each ΔV(ΔH), when |ΔV(ΔH)|>MaxDV, the corresponding δ(ΔH) is an invalid value and should be screened out; when |ΔV(ΔH)|≤MaxDV, the corresponding δ(ΔH) is a valid value and should be screened as a valid enumeration value of the anisotropic parameter.

[0082] If there is no anisotropic parameter enumeration value whose velocity error satisfies the velocity error threshold, it is considered that the velocity information of the well data does not match the calibration information, and a notification of abnormal data of the layer is sent. The interpreter rechecks and adjusts the basic data according to the notification, inputs it, and re-executes the above data acquisition step, i.e., step S11, to avoid local anomalies in the delta field and the anisotropic velocity field.

[0083] Assuming MaxDV = 260 m / s, the velocity error ΔV (ΔH) corresponding to different thickness error enumeration values ​​ΔH is shown in Table 3:

[0084] Table 3 Statistics of velocity errors corresponding to different thickness errors in Well A

[0085]

[0086] In Table 3, the values ​​with absolute velocity errors greater than 260 for layers 4 and 5 are invalid. If the basic data cannot be modified, these data are screened out and do not participate in the subsequent scoring and weighted calculations.

[0087] Step S14: determining the total score of the effective anisotropic parameter enumeration values ​​according to the set velocity weight value, the set thickness weight value, the velocity error and the thickness error enumeration values ​​corresponding to the effective anisotropic parameter enumeration values.

[0088] For details, see Figure 2 As shown, the following steps may be included:

[0089] Step S141: determining a speed item score of the valid anisotropic parameter enumeration value according to the speed error threshold and the speed error corresponding to the valid anisotropic parameter enumeration value.

[0090] For the valid enumeration value of the anisotropic parameter that meets the dual constraints, the speed error threshold MaxDV and the speed error ΔV (ΔH) corresponding to the valid enumeration value of the anisotropic parameter are used to determine the speed item score MarkV (ΔH) of the valid enumeration value of the anisotropic parameter using the following formula (10):

[0091]

[0092] The speed item score statistics corresponding to different thickness error enumeration values ​​ΔH are shown in Table 4:

[0093] Table 4 Velocity score table corresponding to different thickness errors in Well A

[0094]

[0095] Step S142: determining the thickness item score of the valid enumeration value of the anisotropy parameter according to the thickness error enumeration value corresponding to the valid enumeration value of the anisotropy parameter.

[0096] The maximum value of the thickness item score influencing parameter is determined according to the thickness error enumeration value corresponding to the valid enumeration value of the anisotropy parameter and the corresponding relationship between the thickness error and the maximum value of the thickness item score influencing parameter.

[0097] For example, when the absolute value of the thickness error |ΔH|=2, the maximum value of the thickness item score influence parameter m is n=1; when |ΔH|=4, n=2; when |ΔH|=6, n=3; when |ΔH|=8, n=4; when |ΔH|=10, n=5.

[0098] According to the maximum value n of the thickness item score affecting the parameter m, the thickness item score MarkH(ΔH) of the effective enumeration value of the anisotropy parameter is determined using the following formula (11):

[0099]

[0100] Table 5 Statistics of thickness scores of Well A

[0101]

[0102]

[0103] Step S143: determining the total score of the valid enumeration values ​​of the anisotropic parameter according to the set velocity weight value, the set thickness weight value, the velocity item score, and the thickness item score.

[0104] Due to the limitations of the single parameter method, the above two single parameter scores are weighted and the velocity weight value and thickness weight value are set to be W respectively. V and W H , and satisfy W H +W V = 1. For each ΔH and its corresponding δ(ΔH), the final total score FinalMark(ΔH) is:

[0105] FinalMark(ΔH)=W H ×MarkH(ΔH)+W V ×MarkV(ΔH) (12).

[0106] Step S15: Determine the valid enumerated value of the anisotropy parameter with the highest total score as the optimal value of the anisotropy parameter of the layer system.

[0107] All δ that satisfy the double constraints * The solution with the highest total score in (ΔH) is the global optimal solution and is determined as the optimal value of the anisotropy parameter of the layer system.

[0108] When W H = 1, the solution with the smallest thickness error among the selected values ​​is taken as the solution of the double parameter constraint, which is the thickness error priority method; when W V =1, the solution with the smallest speed error among the selected values ​​is taken as the solution of the double parameter constraint, which is the speed error priority method; design weighting factor: W V =0.666 and W H =0.334, the total scores are shown in Table 6, and the solution with the highest total score is selected as the optimal solution.

[0109] Table 6 Total score of double parameter constraint for different thickness errors in Well A

[0110]

[0111] The double-parameter constraint delta calculation takes into account both depth error and velocity error, resulting in a more reasonable and reliable solution. Table 7 shows the Delta values ​​and corresponding thickness and velocity errors obtained using the traditional single-parameter constraint method, thickness-priority method, velocity-priority method, and the double-parameter constraint method of the present invention. The single-parameter constraint method minimizes the thickness error, but the velocity error is uncontrollable. The velocity error corresponding to the calculation result of layer 4 is too large, exceeding 300 m / s. The Delta value obtained by prioritizing the thickness term has a smaller thickness error and a controllable velocity error. For example, the velocity error corresponding to the calculation result of layer 4 is less than MaxDV = 260 m / s. The Delta value obtained by prioritizing the velocity term has the smallest velocity error and a controllable thickness error, less than MaxDH = 10. The Delta value obtained by the double-parameter weighted method used in this embodiment meets the requirements for both thickness and velocity errors, thus achieving the optimal solution.

[0112] Table 7 Anisotropic parameter delta table for single parameter constraint and double parameter constraint

[0113]

[0114] The anisotropy parameter determination method provided by the present invention determines multiple thickness error enumeration values ​​for each layer based on a thickness error threshold. The corresponding anisotropy parameter enumeration value is determined based on each thickness error enumeration value, the well calibration thickness, and isotropic thickness of the layer. The corresponding velocity error is determined based on the anisotropy parameter enumeration value, the well logging velocity, and the isotropic velocity of the layer. Anisotropy parameter enumeration values ​​whose velocity errors meet the velocity error threshold are selected as valid anisotropy parameter enumeration values. This method utilizes well stratification and actual seismic stratification information to determine the Delta value constrained by the thickness error threshold for the layer. Furthermore, it utilizes well logging velocity and seismic velocity information to determine the Delta value constrained by the velocity error threshold for the layer. An innovative method for obtaining anisotropic Delta parameters was developed through the dual-parameter constraints of thickness error threshold and velocity error threshold. This effectively avoids the defects of the industry's commonly used method of obtaining layer thickness through well stratification calibration and single-parameter Delta calculation, such as anisotropic Delta errors caused by well stratification errors or incorrect well stratification. The selected valid enumeration values ​​of the anisotropic parameters meet both the thickness error threshold and the velocity error threshold. Then, based on the set velocity weight value, the set thickness weight value, and the velocity error and thickness error enumeration values ​​corresponding to the valid enumeration values ​​of the anisotropic parameters, the total score of the valid enumeration values ​​of the anisotropic parameters is determined. The valid enumeration value with the highest total score is determined as the optimal value of the anisotropic parameter for the layer system, further ensuring the rationality of the Delta value.

[0115] In actual seismic exploration areas, dual-parameter constrained anisotropic Delta parameter calculations are performed on all well points within the area. This method can also identify errors in the calculation of anisotropic Delta parameters caused by incorrect well stratification. Delta values ​​with large errors or errors obtained with single-parameter constraints can be corrected or deleted to obtain more accurate and reasonable Delta parameters, effectively avoiding the occurrence of false underground geological structures and reducing well deployment and drilling risks.

[0116] The optimal value of anisotropic parameters is determined by calculation through well-seismic layering data, logging velocity, and isotropic seismic velocity, which is highly efficient, low-cost and has a wide range of applications.

[0117] Based on the inventive concept of the present invention, an embodiment of the present invention further provides an anisotropic parameter determination device, the structure of which is as follows: Figure 3 Shown, including:

[0118] The data acquisition module 31 is used to obtain the thickness error threshold, velocity error threshold, and the well calibration thickness, isotropic thickness, logging velocity, and isotropic velocity of each layer;

[0119] The anisotropic parameter determination module 32 is used to perform the following anisotropic parameter determination steps for each layer system: determine multiple thickness error enumeration values ​​according to the thickness error threshold value, determine the corresponding anisotropic parameter enumeration value according to each thickness error enumeration value, the well calibration thickness and isotropic thickness of the layer system; determine the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity and isotropic velocity of the layer system, and screen the anisotropic parameter enumeration values ​​whose velocity errors meet the velocity error threshold value as the effective anisotropic parameter enumeration values; determine the total score of the effective anisotropic parameter enumeration values ​​according to the set velocity weight value, the set thickness weight value and the effective anisotropic parameter enumeration values, and the corresponding velocity error and thickness error enumeration values; and determine the effective anisotropic parameter enumeration value with the highest total score as the optimal anisotropic parameter value of the layer system.

[0120] 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.

[0121] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a computer program product with an anisotropy parameter calculation function, including a computer program / instruction, wherein the computer program / instruction implements the above-mentioned anisotropy parameter determination method when executed by a processor.

[0122] 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.

[0123] 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.

[0124] 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 method for determining anisotropy parameters, characterized in that: include: Data acquisition step, obtaining thickness error threshold, velocity error threshold and well calibration thickness, isotropic thickness, logging velocity and isotropic velocity of each layer; The following steps for determining anisotropy parameters are performed for each layer system: According to the thickness error threshold, multiple thickness error enumeration values ​​are determined. According to the thickness error enumeration value ΔH, the well calibration thickness H0 of the layer system, and the isotropic thickness H1, the anisotropic parameter enumeration value δ(ΔH) corresponding to the thickness error enumeration value ΔH is determined using the following formula (1): Determine the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity and the isotropic velocity of the layer system, and select the anisotropic parameter enumeration value whose velocity error meets the velocity error threshold as the valid anisotropic parameter enumeration value; According to the speed error threshold MaxDV and the speed error ΔV (ΔH) corresponding to the valid enumeration value of the anisotropy parameter, the speed item score MarkV (ΔH) of the valid enumeration value of the anisotropy parameter is determined using the following formula (2): Determine the maximum value of the thickness item score influencing parameter according to the thickness error enumeration value corresponding to the valid enumeration value of the anisotropy parameter and the corresponding relationship between the thickness error and the maximum value of the thickness item score influencing parameter; According to the maximum value n of the thickness item score affecting the parameter m, the thickness item score MarkH (ΔH) of the effective enumeration value of the anisotropy parameter is determined using the following formula (3): Determining a total score of valid enumeration values ​​of the anisotropy parameter according to a set velocity weight value, a set thickness weight value, the velocity item score, and the thickness item score; The valid enumeration value of the anisotropy parameter with the highest total score is determined as the optimal value of the anisotropy parameter of the layer system.

2. The method according to claim 1, wherein The method of determining the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity of the layer and the isotropic velocity specifically includes: According to the anisotropic parameter enumeration value δ(ΔH) and the isotropic velocity V of the layer system I , use the following formula (4) to determine the anisotropic velocity calculation value V corresponding to the thickness error enumeration value ΔH A (ΔH): The value V is calculated based on the anisotropic velocity A (ΔH) and the logging velocity V0 of the layer, and use the following formula (5) to determine the corresponding velocity error ΔV(ΔH): ΔV(ΔH)=V A (ΔH)-V0(5)。 3. The method according to claim 1, wherein The determining of the total score of the valid enumeration values ​​of the anisotropy parameter according to the set velocity weight value, the set thickness weight value, the velocity item score, and the thickness item score specifically includes: According to the set speed weight value W V , set the thickness weight value W H , velocity item score MarkV(ΔH) and thickness item score MarkH(ΔH), and use the following formula (6) to determine the total score FinalMark(ΔH) of the valid enumeration value of the anisotropic parameter: FinalMark(ΔH)=W H ×MarkH(ΔH)+W V ×MarkV(ΔH)(6)。 4. The method according to any one of claims 1 to 3, wherein: Also includes: The strata between the base level and the adjacent control horizon are determined as one stratum system, and the strata between two adjacent control horizons are determined as one stratum system.

5. The method according to any one of claims 1 to 3, wherein: Also includes: If there is no anisotropy parameter enumeration value whose velocity error satisfies the velocity error threshold, a notification of abnormal data of the layer system is sent, and the data acquisition step is executed again.

6. A device for determining anisotropy parameters, characterized in that: include: Data acquisition module, used to obtain thickness error threshold, velocity error threshold and well calibration thickness, isotropic thickness, logging velocity and isotropic velocity of each layer; The anisotropy parameter determination module is used to perform the following anisotropy parameter determination steps for each layer system: According to the thickness error threshold, multiple thickness error enumeration values ​​are determined. According to the thickness error enumeration value ΔH, the well calibration thickness H0 of the layer system, and the isotropic thickness H1, the anisotropic parameter enumeration value δ(ΔH) corresponding to the thickness error enumeration value ΔH is determined using the following formula (1): Determine the corresponding velocity error according to the anisotropic parameter enumeration value, the logging velocity and the isotropic velocity of the layer system, and select the anisotropic parameter enumeration value whose velocity error meets the velocity error threshold as the valid anisotropic parameter enumeration value; According to the speed error threshold MaxDV and the speed error ΔV (ΔH) corresponding to the valid enumeration value of the anisotropy parameter, the speed item score MarkV (ΔH) of the valid enumeration value of the anisotropy parameter is determined using the following formula (2): Determine the maximum value of the thickness item score influencing parameter according to the thickness error enumeration value corresponding to the valid enumeration value of the anisotropy parameter and the corresponding relationship between the thickness error and the maximum value of the thickness item score influencing parameter; According to the maximum value n of the thickness item score affecting the parameter m, the thickness item score MarkH (ΔH) of the effective enumeration value of the anisotropy parameter is determined using the following formula (3): Determining a total score of valid enumeration values ​​of the anisotropy parameter according to a set velocity weight value, a set thickness weight value, the velocity item score, and the thickness item score; The valid enumeration value of the anisotropy parameter with the highest total score is determined as the optimal value of the anisotropy parameter of the layer system.

7. A computer program product having anisotropic parameter calculation function, comprising a computer program / instructions, wherein: When the computer program / instruction is executed by a processor, the method for determining anisotropy parameters according to any one of claims 1 to 5 is implemented.

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