Method for extracting velocity spectrum from DAS data, readable storage medium and electronic equipment

Abstract

The invention provides a method for extracting a velocity spectrum from DAS data, and the method comprises the following steps: dividing the DAS data of a whole well section into a plurality of data blocks according to a set depth interval, and obtaining a frequency-wave number diagram corresponding to each data block; performing grid division on each frequency-wave number diagram; obtaining a power spectrum of each grid; setting a plurality of slope lines with different slope values through the original point of the frequency-wave number diagram, wherein each slope value is within a preset slope value range; aiming at each frequency-wave number diagram, an integral value of each set slope line is calculated, and the integral value is a weighted average value of a length value of the slope line in each grid penetrated by the slope line and a power spectrum in the grid; the slope value of the slope line corresponding to the maximum integral value is used as a static speed value corresponding to the data block where the slope line is located; splicing the static velocity values corresponding to the data blocks to obtain a static velocity spectrum corresponding to the DAS data of the whole well section; and according to the static velocity spectrum and the fluid velocity in the wellbore, velocity spectrums of upgoing waves and downgoing waves in the wellbore are obtained.

Description

Technical Field

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

[0002] DAS technology, or distributed acoustic sensing technology, is a technology that uses the Rayleigh backscattered light information of optical fibers to detect acoustic waves along optical fibers. DAS technology is mainly composed of two parts: a demodulator and an optical fiber. In the field of oil and gas engineering, DAS technology can be used to obtain acoustic wave data of oil wells. When applied, the optical fiber is coupled to 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 disturbed by the fluid in the wellbore and generates strain, the refractive index of the optical fiber at that position will change, causing the phase of the backscattered light to change. Since the phase change of Rayleigh backscattered light is linearly related to 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 DAS technology is distributed acoustic sensing data, or DAS data.

[0003] The sound velocity data can be extracted from the DAS data. In the prior art, the DAS data of the entire well section of the oil well is first divided into data blocks, and then each data block is subjected to frequency-wave number transformation to calculate each frequency-wave number graph. In the frequency-wave number graph, there will be a sound velocity strip that is roughly linearly distributed. The staff manually draws a slope line along the approximate inclination direction of the sound velocity strip. The slope of the slope line represents the sound velocity data corresponding to the data block. For all the divided data blocks, the above manual operation is required. According to the sound velocity data of each data block, the static velocity spectrum of the entire well section is spliced, and the up-going wave velocity spectrum and the down-going wave velocity spectrum of the sound wave are further obtained from the static velocity spectrum. In the existing method, the process of obtaining the sound velocity data is repetitive and cumbersome, and the acquisition efficiency is low. In addition, the staff visually observes the sound velocity strip in the frequency-wave number graph and roughly draws the slope line. The sound velocity data obtained from the slope value of the slope line is not objective and accurate enough, and cannot truly and accurately reflect the sound velocity data in the oil well. Summary of the invention

[0004] In view of this, the present invention provides a method for extracting 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 velocity spectrum from DAS data provided by the present invention comprises the following steps:

[0006] Divide the DAS data of the entire well section into multiple data blocks according to the set depth intervals.

[0007] Obtaining a frequency-wave number diagram corresponding to each of the data blocks;

[0008] Gridding each of the frequency-wave number diagrams;

[0009] Get the power spectrum in each grid;

[0010] 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;

[0011] For each of the frequency-wave number diagrams, calculating the integral value of each of the set slope lines, the integral value being a weighted average of the length of the slope line in each of the grids it passes through and the power spectrum in the grid;

[0012] 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;

[0013] 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;

[0014] 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.

[0015] Optionally, the step of gridding each of the frequency-wave number diagrams specifically includes:

[0016] Obtaining pixel points of the frequency-wave number graph;

[0017] Taking the origin of the frequency-wave number diagram as the starting point, frequency separation lines of the frequency coordinate axis are made every m pixels along the first direction, and wave number separation lines of the wave number coordinate axis are made every n pixels along the second direction perpendicular to the first direction. Every two adjacent frequency separation lines and every two adjacent wave number separation lines enclose a grid.

[0018] Optionally, the power spectrum in each of the grids is an average value of the power spectra at all the pixels in the grid.

[0019] Optionally, the preset slope value range is defined according to the propagation speed of the sound wave in different fluids in the wellbore.

[0020] Optionally, 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:

[0021] The static speed value corresponding to each data block is normalized.

[0022] Optionally, for each of the frequency-wave number diagrams, calculating the integral value of each of the set slope lines comprises the following steps:

[0023] (1) determining the coordinates (x0, y0) of the entry point of the slope line into any of the grids, and the coordinates (x1, y1) of the exit point of the slope line from the grid;

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

[0025]

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

[0027]

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

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

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

[0031] F ij is the power spectrum of the i-th grid in the direction of the wave number coordinate axis and the j-th grid in the direction of the frequency coordinate axis.

[0032] Optionally, according to the static velocity spectrum v and the fluid velocity c in the wellbore, the upgoing wave velocity spectrum v in the wellbore is obtained. + and the downgoing wave velocity spectrum v - In the step, the calculation is performed according to the following formula:

[0033] v + =v+c;

[0034] v - =vc.

[0035] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores instruction information readable by a computer, and after the computer reads the instruction information, the computer can execute any of the above-mentioned methods for extracting velocity spectrum from DAS data.

[0036] The present invention also provides an electronic device, comprising at least one processor and at least one memory, wherein at least one of the memories stores instruction information, and after reading the instruction information, at least one of the processors can execute any of the above methods for extracting velocity spectrum from DAS data.

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

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

[0039] By adopting the present invention, the acoustic wave velocity spectrum can be automatically extracted from DAS (distributed acoustic wave sensing) data by software algorithm. The automation process greatly reduces manual intervention and improves data processing efficiency. A series of slope lines with different slope values ​​are set within a certain acoustic wave velocity range (i.e., a series of different acoustic wave velocity values ​​are set), and the velocity value corresponding to the slope line with the largest integral value is selected as the final static velocity value of the well section, which is closer to the true velocity and improves the accuracy of the acoustic wave velocity data. In addition, the use of different slope lines increases directional flexibility, which means that when calculating the integral value, the integral is performed according to the direction of the slope line, rather than the integral within the entire range of the entire frequency-wave number diagram, thereby improving the calculation efficiency and reducing the memory consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of a method for extracting velocity spectrum from DAS data according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the layout of distributed optical fiber sensors;

[0042] Figure 3 A frequency-wave number diagram according to an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of grid division of a frequency-wave number diagram according to an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of an upgoing wave velocity spectrum according to an embodiment of the present invention;

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

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

[0047] Reference numerals:

[0048] 11: oil pipe; 12: casing; 13: optical fiber; 14: demodulator; 21: processor; 22: memory; 23: input device; 24: output device;. DETAILED DESCRIPTION

[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 orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only simplified descriptions for the convenience of describing 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 understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

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

[0051] S101: Divide the DAS data of the entire well section into multiple data blocks according to the set depth intervals, and obtain the frequency-wave number diagram corresponding to each of the data blocks.

[0052] Use distributed fiber optic sensors to obtain DAS data of the entire well section of the oil well. Figure 2 The schematic diagram of the layout of distributed optical fiber sensors is shown in Figure 2. Figure 2 As shown, a casing 12 is arranged outside the oil pipe 11, and a single-mode optical fiber 13 is coupled to the casing 12 and arranged outside the casing 12 along the extension direction of the casing 12. The single-mode optical fiber 13 is connected to a demodulator 14 at one end of the wellhead. The demodulator 14 not only emits laser pulses to the optical fiber 13, but also receives the optical phase change data sent back by the optical fiber 13, and further converts the optical phase change data into acoustic wave data, i.e., the DAS data of the whole well section. The DAS data of the whole well section is too large, and the depth interval is set according to experience, and the DAS data of the whole well section is divided 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 in the time-space domain (TX) and after Fourier transformation, each data block is transformed into the frequency-wavenumber domain (FK). Figure 3 A frequency-wave number diagram according to an embodiment of the present invention is shown in FIG. Figure 3As shown, the horizontal axis is the wave number, the vertical axis is the frequency, and the background is the power spectrum, which is the square value of the Fourier transform amplitude. The bright spots in the frequency-wave number diagram indicate that the energy is stronger under a specific frequency and wave number combination. According to the functional relationship between wave number, frequency and sound wave speed, draw any straight line through the origin on the frequency-wave number diagram, and the slope value of the straight line represents a sound speed value. Because a conjugate result is produced during the Fourier transform process, the presence of negative values ​​on the wave number axis does not affect subsequent data processing.

[0054] S102: Gridding each of the frequency-wave number diagrams.

[0055] On the wave number coordinate axis and the frequency coordinate axis, the frequency-wave number graph is divided into grids set in sequence at certain intervals. The grid division interval can be artificially set in combination with the frequency-wave number specifications and experience, and has no decisive influence on the final velocity spectrum data obtained.

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

[0057] When each data block is converted to the frequency-wave number domain through Fourier transform, each grid range corresponds to a power spectrum, which is the square value of the Fourier transform amplitude.

[0058] S104: setting a plurality of slope lines with different slope values ​​through the origin of the frequency-wave number graph, wherein each slope value is within a preset slope value range.

[0059] The slope value is the propagation speed of the sound wave in the static fluid in the wellbore. The preset slope value range is limited according to the propagation speed of the sound wave in different fluids in the wellbore. There is also water and gas in the oil well. The propagation speed of the sound wave in the gas is 340m / s, the propagation speed in the pure oil is 1050m / s, the propagation speed in the pure water is 1525m / s, and the speed in the gas-water-oil mixed fluid is between 340-1525m / s. Therefore, 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 frequency-wave number diagrams, calculating the integral value of each of the set slope lines, wherein the integral value is a weighted average value of the length of the slope line in each of the grids it passes through and the power spectrum in the grid.

[0061] Slope lines with different slope values ​​pass through multiple grids at different positions in the frequency-wavenumber diagram. Each grid that a slope line passes through corresponds to a slope line of a specific length and has a corresponding power spectrum. The length value of each grid that a slope line passes through is multiplied by the corresponding power spectrum, the product value corresponding to each grid is added, and then the quotient is calculated by the total length of the slope line, which is the integral value corresponding to the slope line.

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

[0063] The larger the integral value, the closer the slope value of the corresponding slope line is to the real sound wave velocity of the depth segment. Compare the integral values ​​corresponding to each slope line, and select the maximum integral value. The slope value of the slope line corresponding to the maximum integral value is the static velocity value corresponding to the data block.

[0064] S107: splicing the static velocity values ​​corresponding to each of the data blocks to obtain a 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 the set depth interval. After obtaining the static velocity value corresponding to each data block, the static velocity values ​​of all different depth sections are spliced ​​together to obtain the static velocity spectrum within the depth range of the entire well section of the oil well.

[0066] S108: Obtain an upgoing wave velocity spectrum and a downgoing wave velocity spectrum in the wellbore according to the static velocity spectrum and the fluid velocity in the wellbore.

[0067] The static velocity spectrum is the velocity of the sound wave when the fluid medium is in a static state. In an oil well, the oil-water mixed fluid is transported toward the ground. Based on the relationship between the upward and downward waves and the fluid flow direction, combined with the static velocity spectrum, the upward and downward wave velocity spectra in the wellbore can be calculated.

[0068] By adopting the method of extracting velocity spectrum from DAS data of the present invention, the acoustic wave velocity spectrum can be automatically extracted from DAS (distributed acoustic sensing) data by software algorithm. The automation process greatly reduces manual intervention and improves data processing efficiency. A series of slope lines with different slope values ​​are set within a certain acoustic wave velocity range (i.e., a series of different acoustic wave velocity values ​​are set), and the velocity value corresponding to the slope line with the largest integral value is selected as the final static velocity value of the well section, which is closer to the actual velocity and improves the accuracy of the acoustic velocity data. In addition, the use of different slope lines increases directional flexibility, which means that when calculating the integral value, the integral is performed according to the direction of the slope line, rather than the integral within the entire frequency-wave number diagram, thereby improving the calculation efficiency and reducing the memory consumption.

[0069] Before performing Fourier transform on each data block to obtain the corresponding frequency-wave number diagram, the following steps may also be included:

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

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

[0072] Optionally, the step of gridding each of the frequency-wave number diagrams specifically includes:

[0073] S301: Obtaining pixel points of the frequency-wave number graph;

[0074] S302: 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.

[0075] There are many pixels distributed at intervals in the frequency-wavenumber diagram. When dividing the grid, the frequency direction and the wavenumber direction can use the same number of pixels as the grid side length, or different numbers of pixels as the grid side length. For example, the frequency and wavenumber directions can use every 5 pixels as the side length of a grid. The first direction is the direction along the frequency coordinate axis, and the second direction is the direction along the wavenumber coordinate axis. The frequency separation line is parallel to the wavenumber coordinate axis, and the wavenumber separation line is parallel to the frequency coordinate axis, so that each grid appears as a rectangle.

[0076] Optionally, the power spectrum in each of the grids is an average value of the power spectra at all the pixels in the grid.

[0077] In a grid, there are multiple pixels, and each pixel has a corresponding power spectrum value. Averaging the power spectra of all the pixels in each grid can reduce the singular value, and then using the power spectrum average value to calculate the integral value of the slope line passing through the grid can improve the accuracy of the integral value result.

[0078] Optionally, 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:

[0079] S401: normalizing the static speed value corresponding to each data block.

[0080] Data normalization maps the data to the same scale range, making the relationship and changes between different features easier to observe and interpret, and helping to better understand the distribution and trend of the data. After normalizing the velocity values ​​corresponding to all databases, the normalized velocity values ​​are obtained. After splicing all the normalized velocity values, the static velocity spectrum within the entire well section is obtained, which can more accurately reflect the relative size of the velocity values ​​of the sound waves between different depth sections of the oil well.

[0081] Optionally, for each of the frequency-wave number diagrams, calculating the integral value of each of the set slope lines comprises the following steps:

[0082] S501: Determine the coordinates (x0, y0) of the entry point of the slope line into any of the grids, and the coordinates (x1, y1) of the exit point of the slope line passing through the grid.

[0083] In the frequency-wavenumber diagram, the horizontal axis is the wavenumber and the vertical axis is the frequency;

[0084] If the slope line passes through the side boundary of the grid, the coordinates of the point where the slope line passes through the side boundary of the grid (x side ,y side )for:

[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 through which the slope line passes in the direction of the wave number coordinate axis, and its value is a positive integer starting from 1;

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

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

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

[0092] If the slope line passes through the upper boundary of the grid, the coordinates of the point where the slope line passes through the upper boundary of the grid (x top ,y top )for:

[0093] y top =jΔy;

[0094]

[0095] Δx top =x top -x0;

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

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

[0098] Δx top is the increment on the wave number coordinate 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 point where the slope line passes 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 direction of the wave number coordinate axis is increased 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 point where the slope line passes 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 coordinate axis direction is increased by 1.

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

[0109] If the slope line passes through the side boundary of the grid, the coordinates of the point of passage (x side ,y side )for:

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

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

[0112] Δx side =x side -x0=Δx;

[0113] If the slope line passes through the upper boundary of the grid, the coordinates of the point where it passes (x top ,y top )for:

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

[0115]

[0116] For a certain slope value m a , correspond Figure 4 The length value Δx1 in , Δx1>Δx, so Δx side <Δx top , the slope line a passes through the side boundary of the grid with index (1,1), and the coordinates of the passing point are (x1, y1) = (Δx, m a At the same time, because the slope line a passes through the side boundary of the grid, the index i in the wave number coordinate axis direction of the position corresponding to the next grid that the slope line a is to pass through must be increased by 1, while j remains unchanged, that is, the index of the second grid that the slope line a passes through 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 the entry point of the slope line a into the second grid. Therefore, for the second grid (i, j) = (2, 1) that the slope line a passes through, the coordinates of its entry point are (x0′, y0′) = (x1, y1) = (Δx, ma Δx).

[0118] If the slope line passes through the side boundary of the grid, the coordinates of the point of passage (x side ,y side )for:

[0119] x side =iΔx=2Δx, 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 passes through the upper boundary of the grid, the coordinates of the point where it passes (x top ,y top )for:

[0123] y top =jΔy=Δy, at this time j=1;

[0124]

[0125] Depend on Figure 4 It can be seen that Therefore, Δx side >Δx top , the slope line a passes through the upper boundary of the grid with index (2, 1), and the coordinates of the point where it passes through are At the same time, because the slope line a passes through the upper boundary of the grid, the index j in the frequency coordinate axis direction of the position corresponding to the next grid that the slope line a is to pass through must be increased by 1, while i remains unchanged, that is, the index of the third grid that the slope line a passes through is (i, j) = (2, 2).

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

[0127] In addition, other methods may be used to determine whether the slope line passes through the side boundary or the upper boundary of the grid. For example, after the grid division is determined, the length and width of the grid are determined, and the coordinates of the four vertices of each grid can be determined. In each grid, the slope value n of the line between the entry point of the slope line into the grid and the vertex in the upper right corner of the grid is calculated. If the slope value n of the line is greater than the slope value m of the slope line, the slope line passes through the side boundary of the grid; if the slope value n of the line is less than or equal to the slope value m of the slope line, the slope line passes through the upper boundary of the grid.

[0128] S 502: Calculate the length l of the slope line in each of the grids it passes through.

[0129]

[0130] In the above steps, the coordinates of the entry point and the exit point of each grid through which the slope line passes have been obtained. According to the Pythagorean theorem, the length l of each grid through which the slope line passes 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, the length l of each grid passed by the slope line is added to obtain the total length L of the slope line, the length of each grid passed by the slope line is multiplied by the power spectrum corresponding to the grid to obtain the product value, the product values ​​corresponding to all the grids passed by the slope line are added, and then divided 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 value of each slope line in the same data block can be calculated, and then the integral values ​​of all slope lines are compared. The slope line corresponding to the largest integral value represents the static velocity value of the sound wave of the data block.

[0135] The same process is applied to all data blocks at different well section depths to obtain the static velocity values ​​of the acoustic waves at all well section depths. The static velocity values ​​of the acoustic waves at all well section depths are spliced ​​together to obtain the static velocity spectrum corresponding to the DAS data of the entire well section.

[0136] Optionally, according to the static velocity spectrum v and the fluid velocity c in the wellbore, the upgoing wave velocity spectrum v in the wellbore is obtained. + and the downgoing wave velocity spectrum v - In the step, the calculation is performed according to the following formula:

[0137] v + =v+c;

[0138] v - =vc;

[0139] The static velocity spectrum obtained from the DAS data is the velocity of the sound wave when the fluid velocity in the wellbore is zero. In reality, the fluid in the wellbore flows upward toward the ground. The upward propagating sound waves are in the same direction as the fluid flow, and the downward propagating sound waves are in the opposite direction of the fluid flow. Therefore, the upward wave velocity spectrum v can be calculated according to the above formula. +and the downgoing wave velocity spectrum v - . Figure 5 A schematic diagram of an upgoing wave velocity spectrum according to an embodiment of the present invention; Figure 6 Schematic diagram of the downgoing wave velocity spectrum according to an embodiment of the present invention, wherein the hollow circles in the figure represent the upgoing / downgoing wave velocity values ​​calculated from the slope values ​​corresponding to the slope line of the integral maximum value within the depth range, the solid dots represent the confidence intervals, and the sound speed range represents the upgoing / downgoing wave velocity range calculated based on each slope line.

[0140] Furthermore, according to the upgoing wave velocity spectrum v + and the downgoing wave velocity spectrum v - , can also be used to calculate the ratio of two-phase flow, which is a direct application of the algorithm results and can help 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, the method for extracting velocity spectrum from DAS data described in any of the above embodiments can be executed.

[0142] Figure 7 FIG. 1 is a schematic diagram of the hardware connection relationship of an electronic device for executing a method for extracting velocity spectrum from DAS data according to an embodiment of the present invention. Figure 7 As shown, the present invention also provides an electronic device, comprising at least one processor and at least one memory, at least one of the memories storing instruction information, and at least one of the processors can execute the method for extracting velocity spectrum from DAS data described in any of the above embodiments after reading the instruction information.

[0143] like 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, may 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, the method for extracting velocity spectrum from DAS data provided in any of the above embodiments is implemented. The memory 22 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the method for extracting velocity spectrum from DAS data, etc. In addition, the memory 22 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 22 may optionally include a memory remotely arranged relative to the processor 21, and these remote memories may be connected to the device for executing the method for extracting velocity spectrum from DAS data through a network. Examples of the above network include, but are not limited to, the Internet, an 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 velocity spectrum from DAS data. The output device 24 can include display devices such as display screens. When the one or more modules are stored in the memory 22 and are executed by the one or more processors 21, the method for extracting velocity spectrum from DAS data in any of the above method embodiments is executed.

[0144] The present invention also provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, implements the method for extracting 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, 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; Gridding each of the frequency-wave number diagrams; 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 diagrams, calculating the integral value of each of the set slope lines, the integral value being a weighted average of the length of the slope line in each of the grids it passes through and the power spectrum in the grid; 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 step of gridding each of the frequency-wave number graphs specifically includes: Obtaining pixel points of the frequency-wave number graph; Taking the origin of the frequency-wave number diagram as the starting point, frequency separation lines of the frequency coordinate axis are made every m pixels along the first direction, and wave number separation lines of the wave number coordinate axis are made every n pixels along the second direction perpendicular to the first direction. Every two adjacent frequency separation lines and every two adjacent wave number separation lines enclose a grid.

3. The method for extracting velocity spectrum from DAS data according to claim 2, 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.

4. The method for extracting velocity spectrum from DAS data according to any one of claims 1 to 3, 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.

5. The method for extracting velocity spectrum from DAS data according to any one of claims 1 to 3, 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.

6. The method for extracting velocity spectrum from DAS data according to any one of claims 1 to 3, characterized in that: The step of calculating the integral value of each slope line for each frequency-wave number diagram comprises the following steps: (1) determining the coordinates (x0, y0) of the entry point of the slope line into any of the grids, and the coordinates (x1, y1) of the exit point of the slope line from the grid; (2) Calculate the length l of the slope line in each of the grids it passes through, (3) Calculate the integral value I of the slope line, Wherein, L 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; F ij is the power spectrum of the i-th grid in the direction of the wave number coordinate axis and the j-th grid in the direction of the frequency coordinate axis.

7. The method for extracting velocity spectrum from DAS data according to any one of claims 1 to 3, characterized in that: According to the static velocity spectrum v and the fluid velocity c in the wellbore, the upward wave velocity spectrum v in the wellbore is obtained. + and the downgoing wave velocity spectrum v - In the step, the calculation is performed according to the following formula: in + =v+c; in - =vc。 8. 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 computer can execute the method for extracting velocity spectrum from DAS data according to any one of claims 1 to 7.

9. 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 7 after reading the instruction information.

10. 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 7 is implemented.

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