Method for Extracting Velocity Spectrum from DAS Data, Readable Storage Medium, and Electronic Device

Abstract

The present invention provides a method for extracting a velocity spectrum from DAS data, comprising the following steps: dividing the full-well-section DAS data into a plurality of data blocks according to a set depth interval, and obtaining a frequency-wavenumber diagram corresponding to each data block; performing grid division on each frequency-wavenumber diagram; obtaining the power spectrum of each grid; setting a plurality of slope lines with different slope values passing through the origin of the frequency-wavenumber diagram, and each slope value is within a preset range of slope values; for each frequency-wavenumber diagram, calculating the integral value of each set slope line, where the integral value is the weighted average of the length value of the slope line within each grid it passes through and the power spectrum within that grid; using the slope value of the slope line corresponding to the maximum integral value as the static velocity value corresponding to the data block where it is located; splicing the static velocity values corresponding to each data block to obtain the static velocity spectrum corresponding to the full-well-section DAS data; and obtaining the up-travel wave and down-travel wave velocity spectra in the wellbore according to the static velocity spectrum and the fluid velocity in the wellbore.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas engineering, and particularly relates to a method for extracting a velocity spectrum from DAS data, a readable storage medium, and an electronic device. Background Art

[0002] The DAS technology, i.e., the distributed acoustic sensing technology, is a technology that uses the information of Rayleigh backscattered light of an optical fiber to detect acoustic waves along the optical fiber. The DAS technology mainly consists of a demodulator and an optical fiber. In the field of oil and gas engineering, the DAS technology can be used to obtain the acoustic wave data of an oil well. During application, the optical fiber is coupled with the casing of the oil well, and the demodulator continuously emits laser pulses to the connected optical fiber. When a certain position of the optical fiber is strained due to the disturbance of the fluid in the wellbore, the refractive index of the optical fiber at this position will change, resulting in a change in the phase of the backscattered light. Since the phase change of the Rayleigh backscattered light has a linear relationship with the acoustic wave acting on the optical fiber, the acoustic wave data can be linearly obtained by demodulating the phase change of the light. The acoustic wave data obtained by the DAS technology is the distributed acoustic sensing data, i.e., the DAS data.

[0003] The acoustic velocity data can be extracted from the DAS data. In the prior art, first, the DAS data of the entire well section of the oil well is divided into data blocks, and then a frequency-wavenumber transform is performed on each data block to calculate the corresponding frequency-wavenumber diagrams. In the frequency-wavenumber diagrams, there will be acoustic velocity bands that are roughly linearly distributed. The staff manually draws a slope line along the approximate inclination direction within the acoustic velocity band, and the slope of this slope line represents the acoustic velocity data corresponding to this data block. For all the divided data blocks, the above manual operations need to be performed. According to the acoustic velocity data of each data block, a static velocity spectrum of the entire well section is spliced, and the upward wave velocity spectrum and the downward wave velocity spectrum of the acoustic wave are further obtained from the static velocity spectrum. In the existing method, the process of obtaining the acoustic velocity data is repetitive and cumbersome, the obtaining efficiency is low, and the staff visually observes the acoustic velocity bands in the frequency-wavenumber diagrams and roughly draws the slope lines. The acoustic velocity data obtained from the slope values of the slope lines is not objective and accurate enough, and cannot truly and accurately reflect the acoustic velocity data in the oil well. Summary of the Invention

[0004] In view of this, the present invention provides a method for extracting a velocity spectrum from DAS data, a computer-readable storage medium, an electronic device, and a computer program product to solve the above technical problems.

[0005] The method for extracting a velocity spectrum from DAS data provided by the present invention includes the following steps:

[0006] Dividing the DAS data of the entire well section into a plurality of data blocks according to a set depth interval,

[0007] Obtaining the frequency-wavenumber diagram corresponding to each of the data blocks;

[0008] Perform meshing on each of the said frequency - wavenumber diagrams;

[0009] Obtain the power spectrum within each grid;

[0010] Set multiple slope lines with different slope values passing through the origin of the frequency - wavenumber diagram, and each of the said slope values is within a preset range of slope values;

[0011] For each of the said frequency - wavenumber diagrams, calculate the integral value of each of the set slope lines, where the integral value is the weighted average of the length value of the slope line within each grid it passes through and the power spectrum within that grid;

[0012] Take the slope value of the slope line corresponding to the maximum integral value as the static velocity value corresponding to the data block where it is located;

[0013] Stitch together the static velocity values corresponding to each of the said data blocks to obtain the static velocity spectrum corresponding to the full - well - section DAS data;

[0014] Based on the static velocity spectrum and the fluid velocity in the wellbore, obtain the up - going wave velocity spectrum and the down - going wave velocity spectrum in the wellbore.

[0015] Optionally, in the step of performing meshing on each of the said frequency - wavenumber diagrams, it specifically includes:

[0016] Obtain the pixel points of the frequency - wavenumber diagram;

[0017] Starting from the origin of the frequency - wavenumber diagram, along the first direction, make frequency separation lines on the frequency axis every m pixel points, and along the second direction perpendicular to the first direction, make wavenumber separation lines on the wavenumber axis every n pixel points. Each adjacent pair of frequency separation lines and adjacent pair of wavenumber separation lines enclose a grid.

[0018] Optionally, for the power spectrum within each grid, use the average value of the power spectra at all the pixel points within that grid.

[0019] Optionally, the preset range of slope values is defined according to the propagation speeds of sound waves in different fluids in the wellbore.

[0020] Optionally, before the step of stitching together the static velocity values corresponding to each of the said data blocks to obtain the static velocity spectrum corresponding to the full - well - section DAS data, the following steps are further included:

[0021] Perform normalization processing on the static velocity values corresponding to each of the said data blocks.

[0022] Optionally, for each of the frequency - wavenumber diagrams, calculating the integral value of each set slope line includes the following steps:

[0023] (1) Determine the coordinates (x0, y0) of the entry point where the slope line enters any one of the grids, and the coordinates (x1, y1) of the exit point where it exits the grid;

[0024] (2) Calculate the length l of the slope line within each grid it passes through,

[0025]

[0026] (3) Calculate the integral value I of the slope line,

[0027]

[0028] where L is the total length of the slope line;

[0029] M is the maximum value of the grid in the wavenumber axis direction in the frequency - wavenumber diagram;

[0030] N is the maximum value of the grid in the frequency axis direction in the frequency - wavenumber diagram;

[0031] F ij is the power spectrum located in the i - th grid in the wavenumber axis direction and the j - th grid in the frequency axis direction.

[0032] Optionally, in the step of obtaining the up - going wave velocity spectrum v + and the down - going wave velocity spectrum v - in the wellbore according to the static velocity spectrum v and the fluid velocity c in the wellbore, the calculation is performed according to the following formula:

[0033] v + = v + c;

[0034] v - = v - c.

[0035] The present invention also provides a computer - readable storage medium, in which instruction information readable by a computer is stored. After the computer reads the instruction information, it can execute the method for extracting the velocity spectrum from DAS data described in any one of the above.

[0036] The present invention also provides an electronic device, including at least one processor and at least one memory. Instruction information is stored in at least one of the memories. After at least one of the processors reads the instruction information, it can execute the method for extracting the velocity spectrum from DAS data described in any one of the above.

[0037] The present invention also provides a computer program product, comprising a computer program / instructions, characterized in that when the computer program / instructions are executed by a processor, the method for extracting a velocity spectrum from DAS data described in any one of the above is implemented.

[0038] The above technical solution provided by the present invention has at least the following beneficial effects compared with the prior art:

[0039] By using the present invention, a software algorithm can be used to automatically extract the acoustic wave velocity spectrum from DAS (Distributed Acoustic Sensing) data. The automated process greatly reduces manual intervention, improves data processing efficiency, and sets a series of slope lines with different slope values (i.e., sets a series of different acoustic wave velocity values) within a certain acoustic wave velocity range, and selects the velocity value corresponding to the slope line with the largest integral value as the final static velocity value of this well section, which is closer to the true velocity and improves the accuracy of the acoustic velocity data. In addition, the method of using different slope lines increases the direction flexibility. The direction flexibility means that when calculating the integral value, the integration is carried out according to the direction of the slope line, rather than integrating over the entire range of the whole frequency-wavenumber diagram, thereby improving the calculation efficiency and reducing the memory consumption. Description of the Drawings

[0040] Figure 1 It is a flowchart of the method for extracting a velocity spectrum from DAS data according to an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of the layout of a distributed fiber optic sensor;

[0042] Figure 3 It is a frequency-wavenumber diagram according to an embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of the grid division of the frequency-wavenumber diagram according to an embodiment of the present invention;

[0044] Figure 5 It is a schematic diagram of the upward wave velocity spectrum according to an embodiment of the present invention;

[0045] Figure 6 It is a schematic diagram of the downward wave velocity spectrum according to an embodiment of the present invention;

[0046] Figure 7 It is a schematic diagram of the hardware connection relationship of an electronic device for executing the method for extracting a velocity spectrum from DAS data according to an embodiment of the present invention.

[0047] Reference Signs:

[0048] 11: tubing; 12: casing; 13: optical fiber; 14: demodulator; 21: processor; 22: memory; 23: input device; 24: output device;. Detailed Implementation Manner

[0049] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of simplifying the description of the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0050] Figure 1 This is a flowchart of the method for extracting the velocity spectrum from DAS data according to an embodiment of the present invention. As Figure 1 shown, the method for extracting the velocity spectrum from DAS data includes the following steps:

[0051] S101: Divide the full-well-section DAS data into multiple data blocks according to a set depth interval, and obtain the frequency-wavenumber diagram corresponding to each data block.

[0052] Use a distributed fiber optic sensor to obtain the full-well-section DAS data of the oil well. Figure 2 This is a schematic layout diagram of the distributed fiber optic sensor. As Figure 2 shown, a casing 12 is sleeved outside the tubing 11. A single-mode optical fiber 13 is coupled with the casing 12 and laid outside the casing 12 along the extending direction of the casing 12. One end of the single-mode optical fiber 13 at the wellhead is connected to a demodulator 14. The demodulator 14 not only emits laser pulses to the optical fiber 13, but also receives the optical phase change data returned by the optical fiber 13, and further converts the optical phase change data into acoustic wave data, that is, the full-well-section DAS data. The full-well-section DAS data is too large. According to experience, set the depth interval, and divide the full-well-section DAS data into multiple data blocks according to the depth interval. For example, the depth interval can be set to 200m.

[0053] The original DAS data is time-space domain (T-X) data. After Fourier transform, each data block is respectively transformed into the frequency-wavenumber domain (F-K). Figure 3 This is the frequency-wavenumber diagram according to an embodiment of the present invention. As Figure 3As shown, the abscissa is the wave number, the ordinate is the frequency, the background is the power spectrum, that is, the square value of the Fourier transform amplitude. The bright spots in the frequency-wave number diagram indicate stronger energy at specific combinations of frequency and wave number. According to the functional relationship between the wave number, frequency, and acoustic wave velocity, draw an arbitrary straight line through the origin in the frequency-wave number diagram, and the slope value of this straight line represents an acoustic velocity value. During the Fourier transform process, conjugate results will be generated. Therefore, there are negative values on the wave number axis, which does not affect subsequent data processing.

[0054] S102: Perform grid division on each of the said frequency-wave number diagrams.

[0055] On the wave number coordinate axis and the frequency coordinate axis, the frequency-wave number diagram is divided into grids arranged in sequence at certain intervals. The division interval of the grids can be set artificially in combination with the specifications and experience of the frequency-wave number, and it does not have a decisive impact on the finally obtained velocity spectrum data.

[0056] S103: Obtain the power spectrum within each grid.

[0057] When each data block is transformed by Fourier transform to the frequency-wave number domain, there is a corresponding power spectrum within the range of each grid. The power spectrum is the square value of the Fourier transform amplitude.

[0058] S104: Set multiple slope lines with different slope values through the origin of the said frequency-wave number diagram, and each of the said slope values is within a preset range of slope values.

[0059] The slope value is the propagation velocity of the acoustic wave in the static fluid in the wellbore. The preset range of slope values is limited according to the propagation velocities of the acoustic wave in different fluids in the wellbore. There is also water and gas in the oil well. The propagation velocity of the acoustic wave in the gas is 340 m / s, in pure oil is 1050 m / s, in pure water is 1525 m / s, and the velocity in the gas-water-oil mixed fluid is between 340 - 1525 m / s. Thus, in the frequency-wave number diagram, a series of slope lines are set through the origin so that the slope values of all slope lines are within the above range.

[0060] S105: For each of the said frequency-wave number diagrams, calculate the integral value of each set slope line, and the integral value is the weighted average of the length value of the slope line within each grid it passes through and the power spectrum within that grid.

[0061] Slope lines with different slope values pass through multiple grids at different positions in the frequency-wave number diagram. Each grid passed through has a specific length of the slope line and a corresponding power spectrum. Multiply the length value of each grid passed through by a slope line with the corresponding power spectrum, add up the product values corresponding to each grid, and then divide by the total length of the slope line, which is the integral value corresponding to that slope line.

[0062] S106: Use the slope value of the slope line corresponding to the maximum integral value as the static velocity value corresponding to the data block where it is located.

[0063] The larger the integral value, the closer the slope value of the corresponding slope line is to the true acoustic velocity of the depth segment where it is located. Compare the integral values corresponding to each slope line, and select the maximum integral value from them. Then, for the slope line corresponding to the maximum integral value, its slope value is the static velocity value corresponding to the data block.

[0064] S107: Concatenate the static velocity values corresponding to each data block to obtain the static velocity spectrum corresponding to the DAS data of the entire well section.

[0065] The original DAS data is divided into multiple data blocks according to a set depth interval. After obtaining the static velocity value corresponding to each data block, concatenate the static velocity values of all different depth segments to obtain the static velocity spectrum within the depth range of the entire well section of the oil well.

[0066] S108: According to the static velocity spectrum and the fluid velocity in the wellbore, obtain the upward wave velocity spectrum and the downward wave velocity spectrum in the wellbore.

[0067] The static velocity spectrum is the acoustic velocity when the fluid medium in the wellbore is in a static state. In the oil well, the oil-water mixed fluid is transported towards the ground. Then, according to the relationship between the upward wave and the downward wave and the fluid flow direction, combined with the static velocity spectrum, the upward wave velocity spectrum and the downward wave velocity spectrum in the wellbore can be calculated.

[0068] Using the method for extracting the velocity spectrum from DAS data of the present invention, the acoustic velocity spectrum can be automatically extracted from DAS (Distributed Acoustic Sensing) data by a software algorithm. The automated process greatly reduces manual intervention, improves data processing efficiency, and sets a series of slope lines with different slope values (i.e., sets a series of different acoustic velocity values) within a certain acoustic velocity range, and selects the velocity value corresponding to the slope line with the largest integral value as the final static velocity value of the well section, which is closer to the true velocity and improves the accuracy of the acoustic velocity data. In addition, using the method of different slope lines increases the direction flexibility. The direction flexibility means that the integration is performed according to the direction of the slope line when calculating the integral value, rather than integrating over the entire range of the frequency - wavenumber diagram, thereby improving the calculation efficiency and reducing the memory consumption.

[0069] Before the step of performing Fourier transform on each data block respectively to obtain the corresponding frequency - wavenumber diagram, the following steps may further be included:

[0070] S201: Perform data preprocessing on each data block.

[0071] In the original DAS data, there may be outliers. Data preprocessing is performed on each data block, including but not limited to filtering, noise reduction, etc., to eliminate noise and interference, ensure the validity of the data, and ensure the reliability of the final result.

[0072] Optionally, in the step of partitioning each of the frequency-wavenumber diagrams into grids, it specifically includes:

[0073] S301: Obtain the pixel points of the frequency-wavenumber diagram;

[0074] S302: Starting from the origin of the frequency-wavenumber diagram, along the first direction, at intervals of m pixel points, draw frequency dividing lines on the frequency axis. Along the second direction perpendicular to the first direction, at intervals of n pixel points, draw wavenumber dividing lines on the wavenumber axis. Each adjacent pair of the frequency dividing lines and each adjacent pair of the wavenumber dividing lines enclose a grid.

[0075] There are many pixel points distributed at intervals in the frequency-wavenumber diagram. When partitioning the grid, the same number of pixel points can be selected as the side length of the grid in the frequency direction and the wavenumber direction, or different numbers of pixel points can be selected as the side length of the grid. For example, in the frequency and wavenumber directions, every 5 pixel points can be used as the side length of a grid respectively. The first direction is along the direction of the frequency axis, the second direction is along the direction of the wavenumber axis, the frequency dividing lines are parallel to the wavenumber axis, and the wavenumber dividing lines are parallel to the frequency axis, so that each grid presents as a rectangle.

[0076] Optionally, for the power spectrum within each grid, the average value of the power spectra at all the pixel points within the grid is selected.

[0077] Within a grid, there are multiple pixel points, and each pixel point has a corresponding power spectrum value. Averaging the power spectra at all the pixel points within each grid can reduce the singular values. Thus, when using the average value of the power spectrum to calculate the integral value of the slope line passing through the grid, the accuracy of the integral value result can be improved.

[0078] Optionally, before the step of splicing the static velocity values corresponding to each data block to obtain the static velocity spectrum corresponding to the full well section DAS data, the following steps are further included:

[0079] S401: Normalize the static velocity values corresponding to each data block.

[0080] Data normalization maps data to the same scale range, making the relationships and variations between different features easier to observe and interpret, and can help better understand the data distribution and trends. After normalizing the velocity values corresponding to all databases, the normalized velocity values are obtained. The static velocity spectrum within the full well section obtained by splicing all the obtained normalized velocity values can more accurately reflect the relative magnitudes of the velocity values between different depth segments of the acoustic wave in the oil well.

[0081] Optionally, calculating the integral value of each set slope line for each of the frequency - wavenumber diagrams includes the following steps:

[0082] S501: Determine the coordinates (x0, y0) of the entry point where the slope line enters any one of the grids, and the coordinates (x1, y1) of the exit point where the slope line exits this grid.

[0083] In the frequency - wavenumber diagram, the abscissa is the wavenumber and the ordinate is the frequency;

[0084] If the slope line exits from the side boundary of the grid, the coordinates (x side , y side ) of the exit point where the slope line exits the side boundary of the grid are:

[0085] x side = iΔx;

[0086] y side = y0 + m(x side - x0);

[0087] Δx side = x side - x0;

[0088] Wherein, i is the index of the grid passed through by the slope line in the wavenumber coordinate axis direction, and the value is a positive integer starting from 1;

[0089] Δx is the lateral width of the grid in the wavenumber coordinate axis direction;

[0090] m is the slope value of the slope line;

[0091] Δx side is the increment on the wavenumber coordinate axis when the slope line passes through the side boundary of the grid;

[0092] If the slope line exits from the upper boundary of the grid, the coordinates (x top , y top ) of the exit point where the slope line exits the upper boundary of the grid are:

[0093] y top = jΔy;

[0094]

[0095] Δx top = x top - x0;

[0096] where j is the index of the grid through which the slope line passes in the frequency axis direction, and the value is a positive integer starting from 1;

[0097] Δy is the longitudinal width of the grid in the frequency axis direction;

[0098] Δx top is the increment on the wave number axis when the slope line passes through the upper boundary of the grid;

[0099] Compare Δx side and Δx top ,

[0100] If Δx side ≤ Δx top , then the slope line passes through the side boundary of the grid, and the coordinates of the passing point of the slope line through the grid are:

[0101] x1 = iΔx;

[0102] y1 = y0 + m(x1 - x0);

[0103] At the same time, the index i of the grid through which the slope line passes in the wave number axis direction is incremented by 1;

[0104] If Δx side > Δx top , then the slope line passes through the upper boundary of the grid, and the coordinates of the passing point of the slope line through the grid are:

[0105] y1 = jΔy;

[0106]

[0107] At the same time, the index j of the grid through which the slope line passes in the frequency axis direction is incremented by 1.

[0108] Figure 4 is a schematic diagram of the grid division of the frequency - wave number diagram according to an embodiment of the present invention. The numbers in the brackets in the figure represent the indices (i, j) of the grid. As Figure 4 shown, taking the slope line a in the figure as an example, its slope value is m a, all the slope lines pass through the origin O of the frequency - wave number diagram. Therefore, the first grid passed through by all the slope lines corresponds to the first grid in the direction of the wave number axis and is also the first grid in the direction of the frequency axis. The grid index (i, j) = (1, 1), and the coordinates (x0, y0) of the entry point of the slope line into the grid with index (1, 1) are the coordinates of the origin O, which are (0, 0).

[0109] If the slope line exits from the side boundary of this grid, the coordinates (x side , y side ) are:

[0110] x side = iΔx = Δx, where i = 1 at this time;

[0111] y side = y0 + m a (x side - x0) = m a Δx;

[0112] Δx side = x side - x0 = Δx;

[0113] If the slope line exits from the upper boundary of the grid, the coordinates (x top , y top ) are:

[0114] y top = jΔy = Δy, where j = 1 at this time;

[0115]

[0116] For a determined slope value m a , corresponding Figure 4 to the length value Δx1 in side , surely, Δx1 > Δx. Therefore, Δx top < Δx a , and the slope line a exits from the side boundary of the grid with index (1, 1), and the coordinates of the exit point (x1, y1) = (Δx, m

[0117] Δx). At the same time, because the slope line a exits from the side boundary of the grid, the index i in the direction of the wave number axis of the position corresponding to the next grid that the slope line a is to pass through must increase by 1, while j remains unchanged. That is, the index of the second grid passed through by the slope line a is (i, j) = (2, 1).

[0117] The coordinates of the exit point of the slope line a from the first grid are the coordinates of its entry point into the second grid. Therefore, for the second grid (i, j) = (2, 1) passed through by the slope line a, its entry point coordinates (x0′, y0′) = (x1, y1) = (Δx, ma Δx).

[0118] If the slope line exits from the side boundary of the grid, the coordinates (x side , y side ) of the exit point are:

[0119] x side = iΔx = 2Δx, where i = 2;

[0120] y side = y0 + m a (x side - x0) = 2m a Δx;

[0121] Δx side = x side - x0 = Δx;

[0122] If the slope line exits from the upper boundary of the grid, the coordinates (x top , y top ) of the exit point are:

[0123] y top = jΔy = Δy, where j = 1;

[0124]

[0125] From Figure 4 it can be seen that Therefore, Δx side > Δx top , the slope line a exits from the upper boundary of the grid with index (2, 1), and the coordinates of the exit point At the same time, since the slope line a exits from the upper boundary of the grid, therefore, for the position of the next grid that the slope line a has to pass through, the index j in the frequency axis direction must increase by 1, while i remains unchanged, that is, the index of the third grid passed through by the slope line a is (i, j) = (2, 2).

[0126] According to the above steps and by analogy, the entry point coordinates and exit point coordinates of each grid passed through by the slope line a are obtained.

[0127] In addition, other methods can also be used to determine whether the slope line exits from the side boundary or the upper boundary of the grid. For example, after the grid division is determined and the length and width of the grid are determined, the coordinates of the four vertices of each grid can be determined. In each grid, calculate the slope value n of the line connecting the entry point where the slope line enters the grid and the upper right vertex of the grid. If the slope value n of the connection line is greater than the slope value m of the slope line, then the slope line exits from the side boundary of the grid; if the slope value n of the connection line is less than or equal to the slope value m of the slope line, then the slope line exits from the upper boundary of the grid.

[0128] S502: Calculate the length l of the slope line within each of the grids it passes through.

[0129]

[0130] In the above steps, the entry point coordinates and exit point coordinates of each grid through which the slope line passes have been obtained. According to the Pythagorean theorem, the length l of the slope line within each grid it passes through can be calculated.

[0131] S503: Calculate the integral value I of the slope line.

[0132]

[0133] Within the grid range of the frequency - wavenumber diagram corresponding to each data block, for each slope line, add up the lengths l of the slope line within each grid it passes through to obtain the total length L of the slope line. Multiply the length of each grid through which the slope line passes by the power spectrum corresponding to that grid to obtain a product value. Add up the product values corresponding to all the grids through which the slope line passes, and then divide by the total length L of the slope line to obtain the integral value of the slope line.

[0134] According to the above process, the integral values of each slope line in the same data block can be calculated and obtained. Then, compare the integral values of all slope lines. The slope value of the slope line corresponding to the maximum integral value represents the static velocity value of the acoustic wave of this data block.

[0135] Apply the same process to all data blocks at different well - section depths, and the static velocity values of the acoustic waves at all well - section depths can be obtained. Concatenate the static velocity values of the acoustic waves at all well - section depths to obtain the static velocity spectrum corresponding to the full - well - section DAS data.

[0136] Optionally, according to the static velocity spectrum v and the fluid velocity c in the wellbore, obtain the up - going wave velocity spectrum v + and the down - going wave velocity spectrum v - in the following steps, calculate according to the following formula:

[0137] v + = v + c;

[0138] v - = v - c;

[0139] The static velocity spectrum obtained from the DAS data is the velocity of the acoustic wave when the fluid velocity in the wellbore is zero. However, in actual situations, the fluid in the wellbore flows upward towards the ground. The up - going acoustic wave has the same direction as the fluid flow, and the down - going acoustic wave has the opposite direction to the fluid flow. Therefore, according to the above formula, the up - going wave velocity spectrum v +With the down - going wave velocity spectrum v - . Figure 5 It is a schematic diagram of the up - going wave velocity spectrum according to an embodiment of the present invention; Figure 6 It is a schematic diagram of the down - going wave velocity spectrum according to an embodiment of the present invention. In the figure, the hollow circles represent the up - going / down - going wave velocity values calculated from the slope values corresponding to the slope lines of the integral maximum within this depth range, the solid dots represent the confidence intervals, and the sound velocity range represents the up - going / down - going wave velocity range calculated from each slope line.

[0140] Furthermore, based on the up - going wave velocity spectrum v + and the down - going wave velocity spectrum v - , it can also be used for the calculation of the two - phase flow ratio, which is a direct application of the algorithm result and can help to more accurately monitor and analyze the fluid composition in pipelines or oil wells.

[0141] The present invention also provides a computer - readable storage medium, in which instruction information readable by a computer is stored. After the computer reads the instruction information, it can execute the method of extracting the velocity spectrum from DAS data described in any of the above embodiments.

[0142] Figure 7 It is a schematic diagram of the hardware connection relationship of an electronic device for executing the method of extracting the velocity spectrum from DAS data according to an embodiment of the present invention. As Figure 7 shown, the present invention also provides an electronic device, including at least one processor and at least one memory. Instruction information is stored in at least one of the memories. After at least one of the processors reads the instruction information, it can execute the method of extracting the velocity spectrum from DAS data described in any of the above embodiments.

[0143] As Figure 7As shown, the electronic device may further include: an input device 23 and an output device 24. The processor 21, the memory 22, the input device 23, and the output device 24 may be communicatively connected. The memory 22, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. The processor 21 executes various functional applications and data processing by running the non-volatile software programs, instructions, and modules stored in the memory 22, that is, implements the method for extracting the velocity spectrum from DAS data provided in any of the above embodiments. The memory 22 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the method for extracting the velocity spectrum from DAS data, etc. In addition, the memory 22 may include high-speed random access memory and may also include non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 22 may optionally include a memory remotely set relative to the processor 21, and these remote memories can be connected to the device for executing the method for extracting the velocity spectrum from DAS data through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof. The input device 23 can receive input user clicks and generate signal inputs related to user settings and function controls of the method for extracting the velocity spectrum from DAS data. The output device 24 may include a display device such as a display screen. When the one or more modules are stored in the memory 22 and run by the one or more processors 21, the method for extracting the velocity spectrum from DAS data in any of the above method embodiments is executed.

[0144] The present invention also provides a computer program product, including a computer program / instructions, which when executed by a processor, implements the method for extracting the velocity spectrum from DAS data described in any of the above embodiments.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting velocity spectrum from DAS data, characterized in that: The steps include: Divide the DAS data of the entire well section into multiple data blocks according to the set depth interval, and obtain the frequency-wave number diagram corresponding to each of the data blocks; Grid division is performed on each of the frequency-wave number diagrams, specifically comprising: Obtaining pixel points of the frequency-wave number graph; Taking the origin of the frequency-wave number diagram as the starting point, along a first direction, at intervals of m pixels, a frequency separation line of the frequency coordinate axis is made; along a second direction perpendicular to the first direction, at intervals of n pixels, a wave number separation line of the wave number coordinate axis is made; and every two adjacent frequency separation lines and every two adjacent wave number separation lines enclose a grid; Get the power spectrum in each grid; Setting a plurality of slope lines with different slope values ​​through the origin of the frequency-wave number graph, each of the slope values ​​being within a preset slope value range; For each of the frequency-wave number graphs, the integral value of each of the set slope lines is calculated. When calculating the integral value, the integral is performed in the direction of the slope line, rather than in the entire range of the entire frequency-wave number graph. The integral value is a weighted average of the length of the slope line in each of the grids passed through and the power spectrum in the grid, specifically comprising the following steps: (1) Determine the coordinates of the entry point of the slope line into any of the grids , and the coordinates of the exit point of the grid ; (2) Calculate the length of the slope line in each of the grids it passes through , ； (3) Calculate the integral value of the slope line , ； in, is the total length of the slope line; M is the maximum value of the grid in the frequency-wave number diagram in the direction of the wave number coordinate axis; N is the maximum value of the grid in the frequency-wave number diagram in the direction of the frequency coordinate axis; is located in the direction of the wave number coordinate axis and located at the same time in the direction of the frequency coordinate axis. The length value of the slope line in each of the grids; is located in the direction of the wave number coordinate axis and located at the same time in the direction of the frequency coordinate axis. A power spectrum within each of the grids; The slope value of the slope line corresponding to the maximum integral value is used as the static speed value corresponding to the data block where the slope line is located; The static velocity values ​​corresponding to each of the data blocks are spliced ​​to obtain a static velocity spectrum corresponding to the DAS data of the entire well section; An upgoing wave velocity spectrum and a downgoing wave velocity spectrum in the wellbore are obtained according to the static velocity spectrum and the fluid velocity in the wellbore.

2. The method for extracting velocity spectrum from DAS data according to claim 1, characterized in that: The power spectrum in each of the grids is the average value of the power spectra at all the pixels in the grid.

3. The method for extracting velocity spectrum from DAS data according to claim 1 or 2, characterized in that: The preset slope value range is defined according to the propagation speed of the sound wave in different fluids in the wellbore.

4. The method for extracting velocity spectrum from DAS data according to claim 1 or 2, characterized in that: Before the step of splicing the static velocity values ​​corresponding to each of the data blocks to obtain the static velocity spectrum corresponding to the full-well section DAS data, the following steps are also included: The static speed value corresponding to each data block is normalized.

5. The method for extracting velocity spectrum from DAS data according to claim 1 or 2, characterized in that: According to the static velocity spectrum and the fluid velocity in the wellbore , obtain the upgoing wave velocity spectrum in the wellbore Downward wave velocity spectrum In the step, the calculation is performed according to the following formula: ； 。 6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instruction information that can be read by a computer. After the computer reads the instruction information, the method for extracting velocity spectrum from DAS data according to any one of claims 1 to 5 can be executed.

7. An electronic device, characterized in that: The method comprises at least one processor and at least one memory, wherein at least one of the memories stores instruction information, and at least one of the processors can execute the method for extracting velocity spectrum from DAS data according to any one of claims 1 to 5 after reading the instruction information.

8. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the method for extracting velocity spectrum from DAS data according to any one of claims 1 to 5 is implemented.

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