Method and apparatus for determining time and location of crack initiation based on das acoustic wave spectrum

Abstract

The application relates to the technical field of hydraulic fracturing of compact oil reservoirs, and provides a method and device for determining a cracking time and position based on a DAS acoustic wave spectrum, the method comprising the following steps: acquiring a DAS acoustic wave signal of a position where a distributed acoustic sensor is located; generating a three-dimensional spectrum diagram of the DAS acoustic wave signal; determining a time corresponding to a situation that a power spectrum density of a specific frequency band in the three-dimensional spectrum diagram meets a preset condition as a cracking time, and determining the position where the distributed acoustic sensor is located as a cracking position. The embodiment of the application can improve the identification accuracy of the cracking time and cracking position of a fracturing crack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic fracturing of tight oil reservoirs, in particular to a method and device for determining the time and position of crack initiation based on DAS acoustic wave spectrum. BACKGROUND

[0002] Hydraulic fracturing technology plays an irreplaceable important role in the development of tight oil reservoirs. It not only can improve the initial production of oil and gas, but also can improve the reservoir reconstruction effect and prolong the production life. With the continuous progress of technology, hydraulic fracturing will play an increasingly important role in the efficient development of unconventional oil and gas resources in China, and make greater contributions to the optimization of energy structure and sustainable development in China.

[0003] Tight oil reservoirs usually have low porosity and poor permeability, and traditional development methods cannot meet the requirements of large-scale and efficient exploitation. Hydraulic fracturing technology can create a complex fracture system in the reservoir by injecting high-pressure liquid into the reservoir, thereby improving the permeability of the reservoir and the flowability of oil and gas. Implementing multi-cluster perforation fracturing on tight oil reservoirs can create a complex fracture system in the reservoir, increasing the effective reconstruction volume of the reservoir. This reconstruction can not only greatly improve the initial production, but also significantly prolong the production cycle of oil and gas and reduce the cost of exploitation. Therefore, the application of hydraulic fracturing technology in the development of tight oil reservoirs is of great importance, and it is one of the core technologies to promote the efficient development and sustainable utilization of unconventional oil and gas resources.

[0004] Although the segmented multi-cluster hydraulic fracturing technology has been successfully promoted and applied, due to the uneven distribution of injected fluid and proppant among different fracturing clusters and the inter-fracture interference effect during the crack initiation process of multi-cluster fractures, there are large differences in crack initiation at different perforation cluster positions, and some perforation clusters may not crack at all. At the same time, due to the large scale of hydraulic fracturing stimulation operation at present, the cement ring along the wellbore direction is often damaged during the process of high-pressure pump injection of fracturing fluid into the formation, thereby forming a channel for the flow of fracturing fluid outside the casing, and even causing hydraulic fracture initiation and propagation at unperforated positions. In order to better evaluate the effect of multi-cluster perforation fracturing and optimize the fracturing design and completion parameters, various types of hydraulic fracturing monitoring technologies have emerged in recent years, including the most widely used distributed optical fiber sensing technology, including distributed temperature sensor (DTS), distributed acoustic sensor (DAS) and distributed strain sensor (DSS). By transmitting continuous laser pulse signals into the optical fiber and receiving and analyzing the Rayleigh scattering, Brillouin scattering and Raman scattering spectrum in the backscattered light, distributed real-time monitoring of vibration, strain and temperature and other physical quantities can be realized.

[0005] Currently, DAS technology has been applied to monitor acoustic signals during the fracturing process in hydraulic fracturing wells. By monitoring the acoustic signals within the wellbore during hydraulic fracturing production enhancement operations, the effectiveness of downhole processes such as bridge plug installation, perforation, ball dropping, and reversal can be monitored. In this type of application, the DAS optical fiber is installed on the outside of the casing and fixed by the cement sheath formed during cementing, creating a good coupling relationship between the casing, cement sheath, and formation. Numerous studies have confirmed that DAS acoustic signals can be used to analyze the fracturing fluid and proppant injection profiles during the fracturing process, thereby understanding the distribution of fracturing fluid and proppant at different perforation cluster locations. DAS acoustic signal analysis methods suggest a correlation between stronger acoustic signals and active fracturing stages or perforation clusters, using the sound pressure level of the DAS acoustic signal to determine the proportion of fracturing fluid and proppant entering the perforation cluster. However, the sound pressure level of the DAS acoustic signal is not directly related to the fracture initiation time and location, frequently leading to misjudgments and inability to evaluate initiation time and location in many field applications. Summary of the Invention

[0006] The purpose of this application is to provide a method and apparatus for determining the initiation time and location of fracturing cracks based on DAS acoustic spectrum, so as to improve the identification accuracy of the initiation time and location of fracturing cracks.

[0007] To achieve the above objectives, in one aspect, embodiments of this application provide a method for determining the crack initiation time and location based on the DAS acoustic spectrum, including:

[0008] Acquire DAS acoustic signals from the locations of distributed acoustic sensors;

[0009] Generate a three-dimensional spectrum of the DAS acoustic signal;

[0010] The moment when the power spectral density of a specific frequency band in the three-dimensional spectrum meets the preset conditions is determined as the crack initiation moment, and the location of the distributed acoustic sensor is determined as the crack initiation location.

[0011] The generation of the three-dimensional spectrum of the DAS acoustic signal includes:

[0012] The DAS acoustic signal is subjected to noise reduction processing;

[0013] The DAS acoustic signal obtained after noise reduction processing is downsampled;

[0014] The downsampled DAS acoustic signal is converted into a DAS acoustic frequency domain signal.

[0015] Calculate the power spectral density of the target time range in the DAS acoustic frequency domain signal, and generate the corresponding three-dimensional spectrum based on the power spectral density.

[0016] The target time range is determined according to a pressure initial rising stage of a pressure curve of the corresponding fracturing stage.

[0017] The specific frequency band includes a frequency band not less than 2000 Hz.

[0018] The preset condition includes:

[0019] The enhancement amplitude of the power spectrum density of the specific frequency band reaches an enhancement threshold.

[0020] The enhancement threshold includes a three-fold enhancement.

[0021] In another aspect, the embodiments of the present application also provide a device for determining a crack initiation time and a crack initiation position based on a DAS acoustic wave spectrum, comprising:

[0022] An acquisition module is configured to acquire a DAS acoustic wave signal of a position where a distributed acoustic sensor is located.

[0023] A generation module is configured to generate a three-dimensional spectrum graph of the DAS acoustic wave signal.

[0024] A determination module is configured to determine a crack initiation time as a time corresponding to a condition that a power spectrum density of a specific frequency band in the three-dimensional spectrum graph meets a preset condition, and determine a crack initiation position as the position where the distributed acoustic sensor is located.

[0025] In another aspect, the embodiments of the present application also provide a computer device, comprising a memory, a processor, and a computer program stored in the memory, wherein the computer program is executed by the processor to execute instructions of the above method.

[0026] In another aspect, the embodiments of the present application also provide a computer storage medium, wherein a computer program is stored in the computer storage medium, and the computer program is executed by a processor of a computer device to execute instructions of the above method.

[0027] In another aspect, the embodiments of the present application also provide a computer program product, wherein the computer program product comprises a computer program, and the computer program is executed by a processor of a computer device to execute instructions of the above method.

[0028] As can be seen from the technical solutions provided by the embodiments of the present application, different from the prior art which directly determines a crack initiation time and a crack initiation position according to a sound pressure level of a DAS acoustic wave signal, the embodiments of the present application can effectively identify rock fracturing sound and non-rock fracturing sound according to a spectrum feature (a power spectrum density of a specific frequency band) of the DAS acoustic wave signal, so as to effectively exclude interference of non-rock fracturing sound of high-frequency transients, thereby improving identification accuracy of the crack initiation time and the crack initiation position of a fracturing crack, and further providing more accurate information for adjusting a hydraulic fracturing site construction, which is beneficial to obtaining a more optimized fracturing reconstruction effect. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This application illustrates a schematic diagram of the application environment for determining the crack initiation time and location based on the DAS acoustic spectrum in some embodiments of this application.

[0031] Figure 2 The flowcharts of methods for determining the crack initiation time and location based on DAS acoustic spectrum in some embodiments of this application are shown.

[0032] Figure 3 It shows Figure 2 The flowchart shown illustrates the process of generating a three-dimensional spectrum of the DAS acoustic signal.

[0033] Figure 4 A schematic diagram showing the energy waterfall diagram of the DAS acoustic signal and the corresponding fracturing operation curve in an exemplary embodiment of this application is illustrated.

[0034] Figure 5a A schematic diagram of the crack initiation location in a three-dimensional spectrum diagram in an exemplary embodiment of this application is shown;

[0035] Figure 5b This illustration shows a schematic diagram of the non-cracked location in a three-dimensional spectrum diagram in an exemplary embodiment of this application;

[0036] Figure 6 The diagram shows a structural block diagram of an apparatus for determining the crack initiation time and location based on the DAS acoustic spectrum in some embodiments of this application.

[0037] Figure 7 A structural block diagram of a computer device in some embodiments of this application is shown.

[0038] [Explanation of Labels in the Attached Image]

[0039] 10. Distributed acoustic sensors;

[0040] 20. Host computer;

[0041] 61. Acquisition module;

[0042] 62. Generation module;

[0043] 63. Determine the module;

[0044] 702, computer device;

[0045] 704, processor;

[0046] 706, memory;

[0047] 708, driving mechanism;

[0048] 710, input / output interface;

[0049] 712, input device;

[0050] 714, output device;

[0051] 716, presentation device;

[0052] 718, graphical user interface;

[0053] 720, network interface;

[0054] 722, communication link;

[0055] 724, communication bus. DETAILED DESCRIPTION

[0056] In order to enable persons skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor should fall within the scope of protection of the present application.

[0057] It should be noted that in the embodiments of the present application, the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved are information and data authorized by the user and fully authorized by all parties, that is, the acquisition, transmission, storage, use, processing, etc. of data in the technical solutions of the present application all comply with the relevant provisions of national laws and regulations.

[0058] Figure 1The application environment schematic diagram for determining the crack initiation time and position based on the DAS acoustic wave spectrum in some embodiments of the present application is shown in FIG. 1. The application environment includes a distributed acoustic sensor 10 and a host computer 20. In some embodiments of the present application, the distributed acoustic sensor 10 is configured to collect the DAS acoustic wave signals at the position thereof and transmit the DAS acoustic wave signals to the host computer 20 in real time. The host computer 20 is configured to generate a three-dimensional spectrum diagram of the DAS acoustic wave signals, determine the crack initiation time as the time corresponding to the power spectrum density of a specific frequency band in the three-dimensional spectrum diagram satisfying a preset condition, and determine the crack initiation position as the position of the distributed acoustic sensor.

[0059] In some embodiments of the present application, the distributed acoustic sensor 10 is a sensor array converting an optical fiber into a distributed acoustic sensor. The high-sensitivity acoustic wave monitoring based on the Rayleigh scattering effect of the optical fiber can realize continuous spatial sensing of physical quantities such as vibration and acoustic wave. For example, the distributed acoustic sensor 10 uses a DAS optical fiber. After the casing is lowered in the well completion process of the fracturing well, the DAS optical fiber is arranged outside the casing and can be tightly connected with the casing using a buckle. Then, cementing is used to ensure that the DAS optical fiber is located between the casing and the cement sheath and is well coupled. Then, the ground related equipment of the DAS optical fiber is debugged to enable normal acoustic wave signal monitoring.

[0060] In some embodiments of the present application, the host computer 20 can be a computer device such as a desktop computer, a tablet computer, a notebook computer, etc. Of course, the host computer 20 is not limited to the above-mentioned computer devices with certain entities. The host computer 20 can also be software running in the above-mentioned computer devices.

[0061] The embodiments of the present application provide a method for determining the crack initiation time and position based on the DAS acoustic wave spectrum, which can be applied to the host computer side. Referring to FIG. 1, the method for determining the crack initiation time and position based on the DAS acoustic wave spectrum in some embodiments of the present application can include the following steps: Figure 2

[0062] Step 201: Obtain the DAS acoustic wave signals at the position of the distributed acoustic sensor.

[0063] Step 202: Generate a three-dimensional spectrum diagram of the DAS acoustic wave signals.

[0064] Step 203: Determine the crack initiation time as the time corresponding to the power spectrum density of a specific frequency band in the three-dimensional spectrum diagram satisfying a preset condition, and determine the crack initiation position as the position of the distributed acoustic sensor.

[0065] ​During the hydraulic fracturing operation, the downhole environment is extremely noisy. In addition to the rock rupture sound events under the action of water pressure, many other sound events (such as support agent particles impacting the casing, the operation vibration of the bridge plug, the friction vibration of the casing itself, etc.) will also generate high-frequency transient DAS acoustic wave signals. The prior art directly determines the fracturing time and the fracturing position according to the sound pressure level of the DAS acoustic wave signal, which is easy to cause misjudgment.

[0066] The inventors of the present application have found that the high-frequency vibration excited by the specific physical event of rock rupture has energy concentrated in a specific frequency band (for example, >2000Hz) that is completely different from noise. Therefore, unlike the prior art which directly determines the fracturing time and the fracturing position according to the sound pressure level of the DAS acoustic wave signal, the embodiments of the present application can effectively identify rock fracturing sound and non-rock fracturing sound according to the frequency spectrum characteristics (power spectrum density of specific frequency band) of the DAS acoustic wave signal, so as to effectively exclude the interference of high-frequency transient non-rock fracturing sound, thereby improving the identification accuracy of the fracturing time and the fracturing position of the fracturing crack, and further providing more accurate information for the adjustment of the hydraulic fracturing site operation, which is beneficial to obtain a more optimized fracturing reconstruction effect.

[0067] In some embodiments of the present application, DAS optical fiber monitoring can be started from the perforation process. The DAS optical fiber acoustic wave signal can be used to accurately locate the perforation or perforation cluster position through the perforation process. The DAS optical fiber can be used to monitor the whole process of the hydraulic fracturing process. Different types of fracturing processes can be monitored, such as ball bridge plug setting, soluble bridge plug isolation, etc. The acoustic wave data (i.e. DAS acoustic wave signal) monitored by the DAS optical fiber and the construction curve of the whole process of the hydraulic fracturing are recorded. The construction curve may, for example, include a pump pressure curve (a curve of pump pressure changing with time), a casing pressure curve (a curve of casing pressure changing with time, such as Figure 4 the first curve below), a displacement curve (a curve of fracturing fluid displacement changing with time, such as Figure 4 the second curve below), and a sand concentration curve (a curve of sand concentration changing with time, such as Figure 4 the third curve below), etc.

[0068] In some embodiments of the present application, the DAS acoustic wave signal at the position of the distributed acoustic sensor refers to receiving the DAS acoustic wave signal sent by the distributed acoustic sensor. The DAS acoustic wave signal is the original acoustic wave data (time domain signal) collected by the distributed acoustic sensor.

[0069] Referring to Figure 3 In some embodiments of the present application, generating the three-dimensional spectrum diagram of the DAS acoustic wave signal may, for example, include the following steps:

[0070] Step 301, performing noise reduction processing on the DAS acoustic wave signal.

[0071] In some embodiments of this application, noise reduction processing of the DAS acoustic signal can reduce or avoid interference signals and redundant signals from the ground and underground in the DAS acoustic signal to a certain extent.

[0072] Step 302: Downsample the DAS acoustic signal obtained by noise reduction processing.

[0073] In some embodiments of this application, downsampling (i.e., appropriately reducing the sampling frequency) of the DAS acoustic signal obtained by noise reduction processing can yield discrete DAS acoustic signals (time-domain discrete signals), which is beneficial to improving the real-time performance of identifying the crack initiation time and location.

[0074] Step 303: Convert the downsampled DAS acoustic signal into a DAS acoustic frequency domain signal.

[0075] In some embodiments of this application, the downsampled DAS acoustic signal (time-domain discrete signal) can be converted into a DAS acoustic frequency domain signal (frequency domain signal) by Fourier transform.

[0076] Step 304: Calculate the power spectral density of the target time range in the DAS acoustic frequency domain signal, and generate the corresponding three-dimensional spectrum based on the power spectral density.

[0077] In some embodiments of this application, the signal power of each frequency component can be calculated based on the DAS acoustic wave frequency domain signal, thereby obtaining the power spectrum (e.g. Figure 4 As shown in the energy waterfall diagram above, the power spectrum includes both amplitude and frequency dimensions, providing a more comprehensive reflection of the signal's energy distribution in the frequency domain. For example, in some embodiments of this application, the power spectrum can be calculated using the formula |X|². Here, X represents the DAS acoustic wave frequency domain signal. If X is represented by the complex number a+bj, then |X|² is the square of the modulus of X. Where a is the real part of X, b is the imaginary part of X, and j is the imaginary unit.

[0078] Based on the obtained power spectrum, the signal power of each frequency component is normalized to make the signal power independent of the frequency bandwidth, thus obtaining the power spectral density, which describes the distribution of signal power across frequencies.

[0079] For example, in some embodiments of this application, the power can be normalized using the formula |X|² / (sampling rate * window function energy) to obtain the power spectral density of each frequency component, and then the corresponding three-dimensional spectrum can be plotted; where * represents convolution operation.

[0080] In the three-dimensional spectrum diagram of the embodiments of the present application, the X axis is time, the Y axis is frequency, and the Z axis is power spectral density. Since the distributed acoustic sensor is an acoustic sensor array distributed at different positions, in some embodiments of the present application, the power spectral densities corresponding to all acoustic sensors in the distributed acoustic sensor can be plotted in the same three-dimensional spectrum diagram for ease of processing.

[0081] In some embodiments of the present application, the target time range is determined according to the pressure initial rise stage of the pressure curve of the corresponding fracturing stage. By setting the target time range, the starting point for effectively generating a three-dimensional spectrum diagram can be determined, and the overhead of drawing an invalid spectrum diagram can be avoided or reduced, thereby facilitating improvement of processing efficiency. The pressure initial rise stage of the pressure curve (such as the rising section on the left side of the casing pressure curve in FIG. 8) can reflect the initial pressurization change of the hydraulic fracturing process, and the pressure initial rise stage can include a typical fracture initiation pressure peak. Figure 4

[0082] In some embodiments of the present application, the preset condition can include that the enhancement amplitude of the power spectral density of a specific frequency band reaches an enhancement amplitude threshold. In this way, by setting the preset condition as that the enhancement amplitude of the power spectral density of a specific frequency band (for example, >2000 Hz) reaches an enhancement amplitude threshold, the fracture initiation time and the fracture initiation position of the fracturing fracture can be efficiently identified on the basis of effectively excluding rock fracturing sound. The enhancement amplitude is relative to the enhancement amplitude before pressurization.

[0083] In some embodiments of the present application, the enhancement amplitude threshold in the preset condition can be, for example, a three-fold enhancement amplitude (300%). The present inventors have further found that when the enhancement amplitude threshold is set to a three-fold enhancement amplitude, the effective fracture initiation time and fracture initiation position can be accurately identified, and the real-time or timeliness of identification can also be taken into account.

[0084] In an exemplary embodiment of the present application, taking the preset condition as an example that the enhancement amplitude of the power spectral density of a specific frequency band (for example, >2000 Hz) reaches a three-fold enhancement amplitude, in the three-dimensional spectrum diagram, if the enhancement amplitude of the power spectral density of a specific frequency band of the DAS acoustic wave signal at a certain position reaches a three-fold enhancement amplitude, it indicates that effective fracture initiation occurs at the position (as indicated in FIG. 8). Figure 5a If the enhancement amplitude of the power spectral density of a specific frequency band of the DAS acoustic wave signal at a certain position does not reach a three-fold enhancement amplitude, it indicates that effective fracture initiation does not occur at the position (as indicated in FIG. 8). Figure 5b

[0085] Although the process flow described above includes a plurality of operations appearing in a specific order, it should be clearly understood that the processes can include more or fewer operations, which can be executed sequentially or in parallel (for example, using a parallel processor or a multi-threaded environment). ​​

[0086] Corresponding to the aforementioned method for determining the crack initiation time and location based on DAS acoustic spectrum, this application also provides an apparatus for determining the crack initiation time and location based on DAS acoustic spectrum, which can be configured on the aforementioned host computer, for reference. Figure 6 As shown in some embodiments of this application, the apparatus for determining the crack initiation time and location based on the DAS acoustic spectrum may include:

[0087] Acquisition module 61 is used to acquire the DAS acoustic signal at the location of the distributed acoustic sensor;

[0088] The generation module 62 is used to generate a three-dimensional spectrum of the DAS acoustic signal;

[0089] The determination module 63 is used to determine the moment when the power spectral density of a specific frequency band in the three-dimensional spectrum meets the preset conditions as the crack initiation moment, and to determine the location of the distributed acoustic sensor as the crack initiation location.

[0090] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0091] Embodiments of this application also provide a computer device. For example... Figure 7 As shown, in some embodiments of this application, the computer device 702 may include one or more processors 704, such as one or more central processing units (CPUs) or graphics processing units (GPUs), each of which may implement one or more hardware threads. The computer device 702 may also include any memory 706 for storing any kind of information such as code, settings, data, etc. In one specific embodiment, a computer program is stored on the memory 706 and can run on the processor 704. When the computer program is run by the processor 704, it can execute instructions of the method for determining the initiation time and location of cracks based on the DAS acoustic spectrum described in any of the above embodiments. Non-limitingly, for example, the memory 706 may include any type of RAM, any type of ROM, flash memory, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Furthermore, any memory can provide volatile or non-volatile retention of information. Furthermore, any memory may represent a fixed or removable component of the computer device 702. In one scenario, when processor 704 executes associated instructions stored in any memory or combination of memories, computer device 702 can perform any operation of the associated instructions. Computer device 702 also includes one or more drive mechanisms 708 for interacting with any memory, such as hard disk drive mechanisms, optical disk drive mechanisms, etc.

[0092] The computer device 702 can also include an input / output interface 710 (I / O) that is used to receive various inputs (via input devices 712) and to provide various outputs (via output devices 714). One particular output mechanism can include a presentation device 716 and an associated graphical user interface 718 (GUI). In other embodiments, the input / output interface 710 (I / O), the input devices 712, and the output devices 714 can not be included, and the computer device 702 can be used merely as a networked computer device. The computer device 702 can also include one or more network interfaces 720 for exchanging data with other devices via one or more communication links 722. One or more communication buses 724 couple the above-described components so that each component can communicate with each other component.

[0093] The communication links 722 can be implemented in any manner, such as through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication links 722 can include any combination of hardwired links, wireless links, routers, gateway functionality, name servers, etc., governed by any protocol or combination of protocols.

[0094] The present application is described with reference to the drawings in which are shown flowcharts and / or block diagrams of methods, apparatus (systems), computer-readable storage media, and computer programs according to some embodiments of the present application. It will be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowcharts and / or block diagrams block or blocks. Figure 1 The flowcharts and / or block diagrams can also be implemented in hardware and / or a combination of hardware and software. Figure 1 The means can be implemented in one or more functional steps in a flow and / or block and / or one or more functional steps in a flow and / or block can be implemented in one or more means.

[0095] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowcharts and / or block diagrams block or blocks. Figure 1 The flowcharts and / or block diagrams can also be implemented in hardware and / or a combination of hardware and software. Figure 1 The means can be implemented in one or more functional steps in a flow and / or block and / or one or more functional steps in a flow and / or block can be implemented in one or more means.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowcharts and / or block diagrams block or blocks. Figure 1one or more processes and / or blocks Figure 1 the steps of a function specified in one or more processes and / or blocks.

[0097] In one typical arrangement, the computer device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0098] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, non-volatile memory, such as read-only memory (ROM), EPROM, and / or flash memory, etc. The memory is an example of computer readable media.

[0099] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic disks storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computer device. According to the definition in this application, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0100] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, system or computer program product. Therefore, the embodiments of the present application can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present application can take the form of a computer program product implemented on one or more computer usable storage media (including but not limited to magnetic disks, CD-ROMs, optical storage devices, etc.) containing computer usable program code.

[0101] The embodiments of the present application can be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The embodiments of the present application can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules can be located in both local and remote computer storage media including memory storage devices.

[0102] It should also be understood that, in the embodiments of the present application, the term "and / or" only means an association relationship of the associated objects, and indicates that there can be three relationships. For example, A and / or B can represent three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects.

[0103] The embodiments of the present application are described in a progressive manner, and the same or similar parts of each embodiment can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

[0104] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0105] The above only describes the embodiments of the present application and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A method for determining the time and location of crack initiation based on the frequency spectrum of DAS acoustic waves, characterized in that, The method comprises the following steps: acquiring a DAS acoustic wave signal at a position where a distributed acoustic sensor is located; generating a three-dimensional frequency spectrum diagram of the DAS acoustic wave signal; specifically, performing noise reduction processing on the DAS acoustic wave signal; performing down-sampling on the DAS acoustic wave signal obtained through the noise reduction processing; converting the DAS acoustic wave signal obtained through the down-sampling into a DAS acoustic wave frequency domain signal; calculating a power spectral density of a target time range in the DAS acoustic wave frequency domain signal, and generating a corresponding three-dimensional frequency spectrum diagram according to the power spectral density; determining a time instant when a power spectral density of a specific frequency band in the three-dimensional frequency spectrum diagram meets a preset condition as a crack initiation time, and determining the position where the distributed acoustic sensor is located as a crack initiation position; the preset condition comprises that an enhancement amplitude of the power spectral density of the specific frequency band reaches an enhancement amplitude threshold; the enhancement amplitude threshold comprises a three-fold enhancement amplitude.

2. The method of determining a time and location of a crack initiation based on a DAS acoustic wave spectrum according to claim 1, wherein, The target time range is determined according to a pressure initial rising stage of a pressure curve of a corresponding fracturing stage.

3. The method of claim 1, wherein the time and location of the crack initiation is determined based on a DAS acoustic wave spectrum. The specific frequency band comprises a frequency band not less than 2000 Hz.

4. An apparatus for determining the time and location of crack initiation based on the spectrum of DAS acoustic waves, characterized by, The method comprises the following steps: an acquisition module, configured to acquire a DAS acoustic wave signal at a position where a distributed acoustic sensor is located; a generation module, configured to generate a three-dimensional frequency spectrum diagram of the DAS acoustic wave signal; specifically, performing noise reduction processing on the DAS acoustic wave signal; performing down-sampling on the DAS acoustic wave signal obtained through the noise reduction processing; converting the DAS acoustic wave signal obtained through the down-sampling into a DAS acoustic wave frequency domain signal; calculating a power spectral density of a target time range in the DAS acoustic wave frequency domain signal, and generating a corresponding three-dimensional frequency spectrum diagram according to the power spectral density; a determination module, configured to determine a time instant when a power spectral density of a specific frequency band in the three-dimensional frequency spectrum diagram meets a preset condition as a crack initiation time, and determine the position where the distributed acoustic sensor is located as a crack initiation position; the preset condition comprises that an enhancement amplitude of the power spectral density of the specific frequency band reaches an enhancement amplitude threshold; the enhancement amplitude threshold comprises a three-fold enhancement amplitude.

5. A computer device comprising a memory, a processor, and a computer program stored on the memory, wherein, The computer program is run by the processor, and instructions of the method according to any one of claims 1-3 are executed.

6. A computer storage medium having stored thereon a computer program, characterized in that The computer program is run by the processor of the computer device, and instructions of the method according to any one of claims 1-3 are executed.

7. A computer program product, characterised in that, The computer program product comprises a computer program, and the computer program is run by the processor of the computer device, and instructions of the method according to any one of claims 1-3 are executed.

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