Acoustic logging curve environment correction method and device and storage medium

Abstract

The invention belongs to the technical field of logging curve environment correction, and particularly relates to an acoustic logging curve environment correction method and device and a storage medium, and the method comprises the steps that a well with VSP data and acoustic logging data in a work area is obtained, and the acoustic logging data is an interval transit time curve; the expanding amount of the whole well section is obtained, and a to-be-corrected well section is determined; performing unit conversion to form a sound wave velocity curve; the resolution ratio of the VSP speed in the VSP data is increased to be consistent with that of the acoustic logging data, and a corrected VSP speed curve is formed; replacing the sound wave velocity value of the well section to be corrected with the corrected VP velocity value on the same depth point to obtain a corrected sound wave velocity curve; and making and calibrating a synthetic seismic record. According to the method, the precision of the acoustic logging curve in the mudstone expanding section can be improved, the seismic calibration precision is improved, and the understanding of the seismic mode is deepened.

Description

Technical Field

[0001] The invention belongs to the technical field of well logging curve environment correction, and in particular relates to an acoustic well logging curve environment correction method, equipment and storage medium. Background Art

[0002] As a porosity logging method, acoustic logging uses the sliding wave of the wellbore to propagate when measuring the acoustic time difference of the formation. When the wellbore expands, it will interfere with the collected acoustic waves, causing deviations in the measured acoustic time difference, resulting in distortion of the calculated porosity, which in turn affects the evaluation of the reservoir performance of the reservoir near the well. The vertical seismic profile is different from the sliding wave of acoustic logging because it receives reflected waves and direct waves from the underground interface and will not be affected by the wellbore environment. However, the VSP measurement point spacing is too large, and the response to some thin layers is not sensitive enough. Therefore, the combination of acoustic logging and VSP logging methods can improve the accuracy of logging data.

[0003] The prior art CN112987098B discloses a method for optimizing a microseismic velocity model based on VSP, which includes the following steps: 1) data preparation, preparing non-zero bias time domain vertical seismic data and acoustic logging data; 2) acoustic velocity model inverted according to perforation data; 3) picking up the first arrival of VSP and calculating the time-depth relationship; 4) calculating the acoustic time-depth relationship; 5) calculating the time difference between the acoustic time-depth relationship and the VSP time-depth relationship; 6) interpolating and resampling the time difference into acoustic point distances and correcting the acoustic waves; 7) locating microseismic events according to the velocity model corrected in step 6). The method provides a method for optimizing a microseismic velocity model based on VSP, which can correct the acoustic logging velocity and further optimize the microseismic velocity model. However, the resolution problem of logging data is not involved.

[0004] Therefore, there is an urgent need to provide a method, equipment and storage medium for environmental correction of acoustic logging curves, to correct the acoustic logging curves in combination with VSP logging curves, and to establish a VSP-AC quantitative relationship, so as to reconstruct VSP curves for wells without VSP data, laying the foundation for subsequent well trajectory optimization and implementation of sidetracking plans. Summary of the invention

[0005] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a method, device and storage medium for environmental correction of acoustic logging curves, which uses VSP technology to correct the acoustic time difference curve of the mudstone expansion section of acoustic logging, so that the corrected acoustic time difference curve meets the effect of seismic calibration.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for environmental correction of an acoustic logging curve, comprising:

[0008] S1. Acquire wells in the work area that have both VSP data and acoustic logging data, where the acoustic logging data is an acoustic time difference curve;

[0009] S2, obtaining the diameter expansion of the entire well section and determining the well section to be corrected;

[0010] S3, converting the units of the acoustic time difference data in the acoustic logging data to be consistent with the units of the VSP velocity in the VSP data, thereby forming an acoustic velocity curve;

[0011] S4, improving the resolution of the VSP velocity in the VSP data to be consistent with the sonic logging data, and forming a modified VSP velocity curve;

[0012] S5, replacing the acoustic wave velocity value of the well section to be corrected with the modified VP velocity value at the same depth point, and then performing smoothing to obtain a corrected acoustic wave velocity curve;

[0013] S6. Use the corrected acoustic wave velocity curve to produce and calibrate synthetic seismic records.

[0014] Furthermore, a threshold value of the diameter expansion amount is set, and a well section with a diameter expansion amount greater than the threshold value is determined as a well section to be corrected, and a well section with a diameter expansion amount less than the threshold value is determined as a normal well section.

[0015] Furthermore, the threshold is 3 inches.

[0016] Furthermore, the specific method for unit conversion in step S3 is: setting the sound wave time difference value to T, then

[0017]

[0018] Where V is the speed of sound waves.

[0019] Furthermore, in step S4, the resolution of the VSP velocity is improved by using a cubic spline interpolation algorithm.

[0020] Furthermore, the specific steps of the cubic spline interpolation algorithm include:

[0021] S401, dividing the VSP velocity curve into several intervals, and fitting a cubic polynomial in each interval;

[0022] S402, setting boundary conditions, thereby obtaining a set of equations for each interval;

[0023] S403, solving the equation system to find the coefficient of each interval;

[0024] S404: Given an interpolation point, use the coefficient to find the function value corresponding to the interpolation point.

[0025] Furthermore, the smoothing process in step S5 refers to smoothing process of a 2 m window length in the entire well section.

[0026] Furthermore, step S6 specifically includes:

[0027] S61, obtaining density curves, post-stack seismic data near the well, geological stratification information, and seismic interpretation horizons, extracting seismic wavelets from seismic traces near the well, and calculating wave impedance at the same time;

[0028] S62, obtaining a synthetic seismic record according to the wave impedance and the seismic wavelet;

[0029] S63. By comparing the geological stratification on the well logging of the synthetic seismic record with the seismic interpretation layer of the actual seismic record, the synthetic seismic record and the actual seismic record are aligned with the same phase axis of amplitude, thus completing the calibration of the synthetic seismic record.

[0030] Furthermore, the synthetic seismic record = wave impedance × seismic wavelet.

[0031] Furthermore, the acoustic logging curve environment correction method also includes:

[0032] S7, calculating the relationship formula between the corrected sonic velocity curve and the VSP velocity curve;

[0033] S8. Using the relationship formula in step S7, calculate the corrected acoustic velocity curve for the well section without VSP data.

[0034] Furthermore, the relationship between the acoustic wave velocity curve and the VSP velocity curve is as follows:

[0035] VSP=a×AC+b

[0036] Wherein, VSP represents VSP velocity data, AC represents acoustic wave velocity data, and a and b are constants.

[0037] The present invention also provides an acoustic logging curve environment correction device, comprising a processor and a memory, wherein the memory stores a computer-readable program executable by the processor; when the processor executes the computer-readable program, the steps in the above-mentioned acoustic logging curve environment correction method are implemented.

[0038] The present invention also provides a computer-readable storage medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the steps in the above-mentioned acoustic logging curve environment correction method.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The method for environmental correction of sonic logging curves provided by the present invention performs unit conversion on sonic logging data and performs resolution processing on VSP data, thereby making the resolution of VSP data consistent with that of sonic logging curves, and then correcting the sonic logging curves, thereby improving the accuracy of sonic logging curves in mudstone expansion sections, improving the accuracy of seismic calibration, and deepening the understanding of seismic modes.

[0041] The method for environmental correction of acoustic logging curves provided by the present invention calculates the relationship between the corrected acoustic velocity curve and the VSP velocity curve, and can correct the acoustic logging curve even without VSP data, thereby greatly improving the correction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a flowchart of the method for environmental correction of acoustic logging curves.

[0043] Figure 2 Schematic diagram of the corrected sound wave velocity curve in an embodiment of the present invention.

[0044] Figure 3 It is a schematic diagram of using the original sound wave curve for calibration in an embodiment of the present invention.

[0045] Figure 4 It is a schematic diagram of calibration using the corrected sound wave velocity curve in an embodiment of the present invention.

[0046] Figure 5 Graph showing the correlation coefficient between the VSP curve and the corrected acoustic wave velocity curve in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the protection scope of the present invention.

[0048] It should be noted that, unless otherwise specifically stated, the relative arrangements of components and steps, and numerical expressions set forth in these embodiments should not be construed as limiting the scope of the present invention.

[0049] The following description of the exemplary embodiments is merely illustrative and is not intended to limit the present invention and its application or use in any sense. Techniques, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail here, but where applicable, these techniques, methods and devices should be considered as part of this specification.

[0050] Embodiment 1

[0051] The present invention provides a method for correcting the environment of acoustic logging curves, including:

[0052] S1. Prepare data. Select two types of well data in the work area (wells with both VSP data and acoustic logging data, and wells with only acoustic logging data). The VSP data is mainly based on the measured VSP velocity, and the acoustic logging data is mainly based on the measured acoustic travel time. In the wells with both VSP data and acoustic logging data, correct the acoustic travel time curve through the VSP velocity and establish a correlation; in the wells without VSP, use this correlation to correct the acoustic travel time curve;

[0053] S2. Determine the well section to be corrected. First, calculate the hole enlargement amount of the entire well section through the bit size - hole enlargement. It is known from experience that the well section with a hole enlargement amount greater than 3 inches is determined as the well section to be corrected, and the well section with a hole enlargement amount less than 3 inches is the normal well section;

[0054] S3. Perform unit conversion on the acoustic travel time data in the acoustic logging data, and convert the unit of the acoustic travel time data to be consistent with the unit of the VSP velocity in the VSP data to form an acoustic velocity curve; The physical quantities represented by the VSP data and the acoustic logging data are different. VSP is velocity with the unit of m / s, while the acoustic travel time in the acoustic logging data is the reciprocal of velocity with the unit of μs / ft. Therefore, to combine these two types of data, unit conversion is required to convert the unit of the acoustic travel time to that of VSP. The specific method of unit conversion is: Set the acoustic travel time value as T, then

[0055]

[0056] where V represents the acoustic velocity; all subsequent acoustic travel time curves are replaced by the acoustic velocity curve;

[0057] S4. Increase the resolution of the VSP velocity in the VSP data to be consistent with that of the acoustic logging data to form a corrected VSP velocity curve;

[0058] The point spacing of the VSP data and the acoustic logging data is different. The point spacing of the VSP data is larger, and its resolution needs to be increased to be consistent with that of the acoustic logging data. Use the cubic spline interpolation algorithm to increase the resolution of the VSP data; The cubic spline interpolation method is a commonly used numerical analysis method that can fit a smooth continuous function curve through a given set of scattered data points. Its basic idea is to approximate the data within a small interval with a low-degree polynomial and use the connection conditions at the joints of these polynomials to ensure the smoothness of the entire curve.

[0059] For the known n data points (xi, yi), where x1 < x2 <... < xn, the cubic spline interpolation method can find a set of functions S(x) and satisfy the following conditions:

[0060] 1. S(x) is a cubic polynomial in each small interval;

[0061] 2. S(x) has the same first-order and second-order derivatives at the connection between two adjacent cells, that is, S'(xi) = S'(xi+1), S"(xi) = S"(xi+1);

[0062] 3. S(x) passes through all given data points, that is, S(xi) = yi.

[0063] The specific steps of the cubic spline interpolation algorithm include:

[0064] S401, dividing the VSP velocity curve into several intervals, and fitting a cubic polynomial in each interval;

[0065] S402, setting boundary conditions, thereby obtaining a set of equations for each interval;

[0066] S403, solving the equation system to find the coefficient of each interval;

[0067] S404: Given an interpolation point, use the coefficient to find the function value corresponding to the interpolation point.

[0068] S5, the acoustic velocity value of the well section to be corrected is replaced by the modified VP velocity value at the same depth point, and then smoothed to obtain a corrected acoustic velocity curve; the VSP curve after cubic spline interpolation is consistent with the acoustic velocity curve to be corrected in resolution, and according to the well section to be corrected calculated in the previous step 2, the acoustic velocity curve value of the well section to be corrected is replaced by the VSP velocity value at the same depth point by direct replacement, and then smoothed with a window length of 2m for the entire well section;

[0069] S6. Using the corrected acoustic wave velocity curve to produce and calibrate synthetic seismic records. Specifically including:

[0070] S61, obtaining density curves, post-stack seismic data near the well, geological stratification information, and seismic interpretation horizons, extracting seismic wavelets from seismic traces near the well, and calculating wave impedance at the same time;

[0071] S62, obtaining a synthetic seismic record according to the wave impedance and the seismic wavelet;

[0072] S63. By comparing the geological stratification on the well logging of the synthetic seismic record with the seismic interpretation layer of the actual seismic record, the synthetic seismic record and the actual seismic record are aligned with the same phase axis of amplitude, thus completing the calibration of the synthetic seismic record.

[0073] Wherein, the synthetic seismic record = wave impedance × seismic wavelet.

[0074] S7, calculating the relationship formula between the corrected acoustic wave velocity curve and the VSP velocity curve; wherein firstly, dimensionless transformation is achieved by a normalization method, and then a corrected velocity curve combining the VSP curve and the acoustic wave time difference curve is fitted by the following formula. Figure 5 Schematic diagram of the correlation between the acoustic wave time difference and the VSP established according to the embodiment of the present disclosure. The relationship between the acoustic wave velocity curve and the VSP velocity curve is:

[0075] VSP=a×AC+b

[0076] Wherein, VSP represents VSP velocity data, AC represents acoustic wave velocity data, and a and b are constants.

[0077] S8. Using the relationship formula in step S7, calculate the corrected acoustic velocity curve for the well section without VSP data. Figure 2 Shown is a schematic diagram of the corrected sound wave velocity curve.

[0078] The reason why the calibration effect of the corrected sound wave velocity curve is better than that of the original sound wave velocity curve is:

[0079] The original acoustic velocity curve cannot measure the true mudstone velocity in the mudstone section due to the influence of diameter expansion, while VSP logging is not affected by the diameter expansion of the mudstone section and can measure the true mudstone velocity. Therefore, the acoustic velocity curve corrected by VSP is better than the original acoustic velocity curve in layer calibration. Figure 3 Schematic diagram of the calibration of the original sound wave curve in this embodiment. Figure 3 As shown in Figure 2, there is a depth shift between seismic events, and the correction effect is general. Figure 4 FIG. 1 is a schematic diagram of calibration of the sound wave curve after correction according to this embodiment. Figure 4 As shown, the corrected acoustic wave curve correlation coefficient ( Figure 4 Medium to dark area ratio Figure 3 The dark area should be larger (the darker the area, the higher the correlation coefficient) than Figure 3 The correlation coefficient shows that the calibration effect of the corrected acoustic wave curve is better than that of the original acoustic wave curve.

[0080] Embodiment 2

[0081] The present invention also provides an acoustic logging curve environment correction device, comprising a processor and a memory, wherein the memory stores a computer-readable program that can be executed by the processor; when the processor executes the computer-readable program, the steps in the acoustic logging curve environment correction method provided in Example 1 are implemented.

[0082] Embodiment 3

[0083] The present invention also provides a computer-readable storage medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the steps in the acoustic logging curve environment correction method provided in Example 1.

[0084] The above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, a person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for environmental correction of acoustic logging curves, It is characterized in that include: S1. Acquire wells in the work area that have both VSP data and acoustic logging data, where the acoustic logging data is an acoustic time difference curve; S2, obtaining the diameter expansion of the entire well section and determining the well section to be corrected; S3, converting the units of the acoustic time difference data in the acoustic logging data to be consistent with the units of the VSP velocity in the VSP data, thereby forming an acoustic velocity curve; S4, improving the resolution of the VSP velocity in the VSP data to be consistent with the sonic logging data, and forming a modified VSP velocity curve; S5, replacing the acoustic wave velocity value of the well section to be corrected with the modified VP velocity value at the same depth point, and then performing smoothing to obtain a corrected acoustic wave velocity curve; S6. Use the corrected acoustic wave velocity curve to produce and calibrate synthetic seismic records.

2. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that A threshold value of the diameter expansion amount is set, and a well section with a diameter expansion amount greater than the threshold value is determined as a well section to be corrected, and a well section with a diameter expansion amount less than the threshold value is determined as a normal well section.

3. The method for environmental correction of acoustic logging curves according to claim 2, It is characterized in that The threshold is 3 inches.

4. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that The specific method for unit conversion in step S3 is: set the sound wave time difference value to T, then Where V is the speed of sound waves.

5. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that In step S4, the resolution of the VSP velocity is improved by using a cubic spline interpolation algorithm.

6. The method for environmental correction of acoustic logging curves according to claim 5, It is characterized in that The specific steps of the cubic spline interpolation algorithm include: S401, dividing the VSP velocity curve into several intervals, and fitting a cubic polynomial in each interval; S402, setting boundary conditions, thereby obtaining a set of equations for each interval; S403, solving the equation system to find the coefficient of each interval; S404: Given an interpolation point, use the coefficient to find the function value corresponding to the interpolation point.

7. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that The smoothing process in step S5 refers to smoothing the entire well section with a window length of 2 m.

8. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that Step S6 specifically includes: S61, obtaining density curves, post-stack seismic data near the well, geological stratification information, and seismic interpretation horizons, extracting seismic wavelets from seismic traces near the well, and calculating wave impedance at the same time; S62, obtaining a synthetic seismic record according to the wave impedance and the seismic wavelet; S63. By comparing the geological stratification on the well logging of the synthetic seismic record with the seismic interpretation layer of the actual seismic record, the synthetic seismic record and the actual seismic record are aligned with the same phase axis of amplitude, thus completing the calibration of the synthetic seismic record.

9. The method for environmental correction of acoustic logging curves according to claim 8, It is characterized in that The synthetic seismic record = wave impedance × seismic wavelet.

10. The method for environmental correction of acoustic logging curves according to claim 1, It is characterized in that The acoustic logging curve environment correction method also includes: S7, calculating the relationship formula between the corrected sonic velocity curve and the VSP velocity curve; S8. Using the relationship formula in step S7, calculate the corrected acoustic velocity curve for the well section without VSP data.

11. The method for environmental correction of acoustic logging curves according to claim 10, It is characterized in that The relationship between the acoustic wave velocity curve and the VSP velocity curve is as follows: VSP=a×AC+b Wherein, VSP represents VSP velocity data, AC represents acoustic wave velocity data, and a and b are constants.

12. An acoustic logging curve environmental correction device, comprising a processor and a memory, wherein the memory stores a computer-readable program executable by the processor; when the processor executes the computer-readable program, the steps in the acoustic logging curve environmental correction method described in any one of claims 1 to 11 are implemented.

13. A computer-readable storage medium storing one or more programs, wherein the one or more programs can be executed by one or more processors to implement the steps in the method for environmental correction of acoustic logging curves according to any one of claims 1 to 11.

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