Method and device for determining crack initiation time and position based on DAS sound wave spectrum

Abstract

The invention relates to the technical field of tight oil reservoir hydraulic fracturing, and provides a method and device for determining the crack initiation moment and position based on a DAS sound wave spectrum, and the method comprises the steps that a DAS sound wave signal of the position where a distributed acoustic sensor is located is obtained; generating a three-dimensional spectrogram of the DAS sound wave signal; and determining a corresponding moment when the power spectral density of a specific frequency band in the three-dimensional spectrogram meets a preset condition as a crack initiation moment, and determining the position of the distributed acoustic sensor as a crack initiation position. According to the embodiment of the invention, the identification precision of the crack initiation moment and the crack initiation position of the fracturing crack can be improved.

Description

Technical Field

[0001] This application relates to the field of hydraulic fracturing technology for tight oil reservoirs, and in particular to a method and apparatus for determining the initiation time and location of fracturing based on DAS acoustic spectrum. Background Technology

[0002] Hydraulic fracturing technology plays an irreplaceable role in the development of tight oil reservoirs. It not only increases initial oil and gas production but also enhances reservoir stimulation and extends production life. With continuous technological advancements, hydraulic fracturing will play an increasingly important role in the efficient development of unconventional oil and gas resources in my country, making a greater contribution to the optimization of my country's energy structure and sustainable development.

[0003] Tight oil reservoirs typically exhibit low porosity and poor permeability, making traditional development methods inadequate for large-scale, efficient extraction. Hydraulic fracturing, by injecting high-pressure fluid into the reservoir, causes rock fractures, creating a fracture network that enhances reservoir permeability and oil and gas flow. Multi-cluster perforation fracturing in tight oil reservoirs can create complex fracture systems, increasing the effective stimulation volume. This stimulation not only significantly increases initial production but also substantially extends the oil and gas production cycle and reduces extraction costs. Therefore, hydraulic fracturing technology plays a crucial role in tight oil reservoir development and is one of the core technologies driving the efficient development and sustainable utilization of unconventional oil and gas resources.

[0004] Although segmented multi-cluster hydraulic fracturing technology has been successfully promoted and applied, the uneven distribution of injected fluid and proppant among the fracturing clusters and the inter-cluster interference during the fracturing initiation process result in significant differences in the fracturing initiation situation at different perforation cluster locations. In some perforation clusters, the fracturing initiation is not even initiated at all. At the same time, due to the large scale of hydraulic fracturing operations, the cement sheath along the wellbore direction is often damaged during the injection of fracturing fluid into the formation at high flow rates and pressures. This creates fracturing fluid flow channels outside the casing, and can even cause hydraulic fracture initiation and propagation at unperforated locations. To better evaluate the effectiveness of multi-cluster perforation fracturing and optimize fracturing design and completion parameters, various types of hydraulic fracturing monitoring technologies have emerged in recent years. Among them, the most widely used distributed fiber optic sensing technology includes distributed temperature sensors (DTS), distributed acoustic sensors (DAS), and distributed strain sensors (DSS). By transmitting continuous laser pulse signals into optical fibers and receiving and analyzing the Rayleigh scattering, Brillouin scattering, and Raman scattering spectra in the backscattered light, distributed real-time monitoring of various physical quantities such as vibration, strain, and temperature can be achieved.

[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 based on the initial pressure rise phase of the pressure curve of the corresponding fracturing stage.

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

[0018] The preset conditions include:

[0019] The increase in power spectral density in a specific frequency band reaches the amplification threshold.

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

[0021] On the other hand, embodiments of this application also provide an apparatus for determining the crack initiation time and location based on the DAS acoustic spectrum, comprising:

[0022] The acquisition module is used to acquire the DAS acoustic signal at the location of the distributed acoustic sensor;

[0023] A generation module is used to generate a three-dimensional spectrum of the DAS acoustic signal;

[0024] The determination module 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.

[0025] On the other hand, embodiments of this application also provide a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the computer program, when run by the processor, executes instructions of the above-described method.

[0026] On the other hand, embodiments of this application also provide a computer storage medium storing a computer program thereon, wherein the computer program, when run by the processor of a computer device, executes instructions for the above-described method.

[0027] On the other hand, this application also provides a computer program product, which includes a computer program that, when run by the processor of a computer device, executes instructions for the above-described method.

[0028] As can be seen from the technical solutions provided by the embodiments of this application above, unlike the prior art which directly determines the fracture time and fracture initiation location based on the sound pressure level of the DAS acoustic signal, the embodiments of this application can effectively identify rock fracturing sound and non-rock fracturing sound based on the spectral characteristics (power spectral density of a specific frequency band) of the DAS acoustic signal. This can effectively eliminate the interference of high-frequency transient non-rock fracturing sound, thereby improving the accuracy of identifying the fracture initiation time and fracture initiation location. This can provide more accurate information for adjusting the on-site construction of hydraulic fracturing, which is conducive to obtaining a more optimized fracturing transformation 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 equipment;

[0045] 704, Processor;

[0046] 706. Memory;

[0047] 708. Drive mechanism;

[0048] 710. Input / output interfaces;

[0049] 712. Input devices;

[0050] 714. Output devices;

[0051] 716. Presentation equipment;

[0052] 718. Graphical User Interface;

[0053] 720. Network interface;

[0054] 722. Communication link;

[0055] 724. Communication bus. Detailed Implementation

[0056] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

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

[0058] Figure 1The diagram illustrates an application environment for determining the crack initiation time and location based on DAS acoustic wave spectrum in some embodiments of this application. This application environment includes a distributed acoustic sensor 10 and a host computer 20. In some embodiments of this application, the distributed acoustic sensor 10 is used to collect DAS acoustic wave signals at its location and transmit the DAS acoustic wave signals to the host computer 20 in real time. The host computer 20 is used to generate a three-dimensional spectrum diagram of the DAS acoustic wave signals. The moment when the power spectral density of a specific frequency band in the three-dimensional spectrum diagram meets preset conditions is determined as the crack initiation time, and the location of the distributed acoustic sensor is determined as the crack initiation location. The three-dimensional spectrum analysis method based on DAS acoustic wave data in the embodiments of this application can more accurately evaluate the crack initiation time and location.

[0059] In some embodiments of this application, the distributed acoustic sensor 10 is a sensor array that converts optical fiber into a distributed acoustic sensor. It can monitor acoustic waves with high sensitivity based on the Rayleigh scattering effect of optical fiber, enabling continuous spatial sensing of physical quantities such as vibration and sound waves. For example, taking the distributed acoustic sensor 10 using DAS optical fiber as an example, after the casing is run in during the completion process of a fractured well, DAS optical fiber is laid on the outside of the casing and can be tightly connected to the casing using clips. Then, cementing is used to ensure that the DAS optical fiber is located between the casing and the cement sheath and that good coupling is maintained. Finally, the surface-related equipment for the DAS optical fiber is debugged to enable it to monitor acoustic signals normally.

[0060] In some embodiments of this application, the host computer 20 can be a desktop computer, tablet computer, laptop computer, or other computer device. Of course, the host computer 20 is not limited to the aforementioned physical computer device; it can also be software running on the aforementioned computer device.

[0061] This application provides a method for determining the crack initiation time and location based on DAS acoustic spectrum, which can be applied to the aforementioned host computer side. (Refer to...) Figure 2 As shown in some embodiments of this application, the method for determining the crack initiation time and location based on the DAS acoustic spectrum may include the following steps:

[0062] Step 201: Obtain the DAS acoustic signal at the location of the distributed acoustic sensor.

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

[0064] Step 203: 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 determine the location of the distributed acoustic sensor as the crack initiation location.

[0065] During hydraulic fracturing operations, the downhole environment is extremely noisy. In addition to the rock fracturing sound events caused by hydraulic action, many other sound events (such as proppant particles impacting the casing, bridge plug operation vibration, and casing friction vibration) also generate high-frequency transient DAS acoustic wave signals. However, existing technologies that directly determine the fracturing time and fracturing initiation location based on the sound pressure level of the DAS acoustic wave signal are prone to misjudgment.

[0066] The inventors of this application have discovered that the high-frequency vibrations excited by the specific physical event of rock fracturing concentrate their energy in a specific frequency band (e.g., >2000Hz) that is distinctly different from noise. Therefore, unlike existing technologies that directly determine the fracturing time and location based on the sound pressure level of DAS acoustic signals, the embodiments of this application can effectively distinguish between rock fracturing sounds and non-rock fracturing sounds based on the spectral characteristics (power spectral density of a specific frequency band) of DAS acoustic signals. This effectively eliminates interference from high-frequency transient non-rock fracturing sounds, thereby improving the accuracy of identifying the fracturing time and location. Consequently, it provides more accurate information for adjusting the on-site hydraulic fracturing operations, which is beneficial for achieving a more optimized fracturing transformation effect.

[0067] In some embodiments of this application, DAS fiber optic monitoring can be performed from the perforation process. The location of the perforation or perforation cluster can be accurately located using DAS fiber optic acoustic signals during the perforation process. The entire hydraulic fracturing process can be monitored using DAS fiber optics, allowing for monitoring of different types of fracturing processes, such as ball-drop bridge plug setting and soluble bridge plug sealing. The entire hydraulic fracturing process construction curve and the acoustic data (i.e., DAS acoustic signals) monitored by the DAS fiber optics are recorded. The construction curve may include, for example, a pump pressure curve (a curve showing pump pressure changing over time) and a casing pressure curve (a curve showing casing pressure changing over time, such as...). Figure 4 The first curve below), the displacement curve (the curve showing the change in fracturing fluid displacement over time, such as...) Figure 4 The second curve below) and the sand concentration curve (the curve showing the change in sand concentration over time, such as...) Figure 4 (The third curve below), etc.

[0068] In some embodiments of this application, obtaining the DAS acoustic signal at the location of the distributed acoustic sensor means receiving the DAS acoustic signal sent by the distributed acoustic sensor. The DAS acoustic signal is the raw acoustic data (time domain signal) collected by the distributed acoustic sensor.

[0069] refer to Figure 3 As shown in some embodiments of this application, generating a three-dimensional spectrum of the DAS acoustic signal may include the following steps:

[0070] Step 301: Perform noise reduction processing on the DAS acoustic 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 this application embodiment, the X-axis represents time, the Y-axis represents frequency, and the Z-axis represents power spectral density. Since the distributed acoustic sensor is an array of acoustic sensors distributed in different locations, in some embodiments of this application, the power spectral density corresponding to all acoustic sensors in the distributed acoustic sensor can be plotted on the same three-dimensional spectrum diagram for easier processing.

[0081] In some embodiments of this application, the target time range is determined based on the initial pressure rise phase of the pressure curve corresponding to the fracturing stage. By setting the target time range, the starting point for effectively generating a three-dimensional spectrum diagram can be determined, avoiding or reducing the overhead of drawing invalid spectrum diagrams, thereby improving processing efficiency. The initial pressure rise phase of the pressure curve (e.g., Figure 4 The rising segment on the left side of the casing pressure curve can reflect the initial pressurization changes in the hydraulic fracturing process. The initial pressure rise stage may include the typical fracture initiation pressure peak.

[0082] In some embodiments of this application, the aforementioned preset condition may include: the enhancement amplitude of the power spectral density in a specific frequency band reaches an amplification threshold. Thus, by setting the preset condition to the enhancement amplitude of the power spectral density in a specific frequency band (e.g., >2000 Hz) reaching an amplification threshold, it is possible to efficiently identify the initiation time and location of hydraulic fracturing cracks while effectively excluding rock fracturing noise. Here, the enhancement amplitude is relative to the steady-state enhancement amplitude before pressurization.

[0083] In some embodiments of this application, the amplification threshold in the above-mentioned preset conditions can be, for example, a three-fold amplification (300%). The inventors of this application have further discovered that when the amplification threshold is set to a three-fold amplification, it can accurately identify the effective crack initiation time and crack initiation location, while also taking into account the real-time or timeliness of the identification.

[0084] In an exemplary embodiment of this application, taking the preset condition that the power spectral density of a specific frequency band (e.g., >2000 Hz) increases by a factor of three as an example, in a three-dimensional spectrum diagram, if the power spectral density of the DAS acoustic signal at a certain location increases by a factor of three in a specific frequency band, it indicates that an effective initiation of cracking has occurred at that location (e.g., Figure 5a (As shown in the figure); if the power spectral density of a specific frequency band of the DAS acoustic signal at a certain location does not increase by a factor of three, it indicates that no effective crack initiation has occurred at that location (e.g. Figure 5b (As shown).

[0085] Although the process described above includes multiple operations that occur in a specific order, it should be clearly understood that these processes may include more or fewer operations that can be executed sequentially or in parallel (e.g., using parallel processors or a multithreaded 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] Computer device 702 may also include an input / output interface 710 (I / O) for receiving various inputs (via input device 712) and providing various outputs (via output device 714). A specific output mechanism may include a presentation device 716 and an associated graphical user interface 718 (GUI). In other embodiments, the input / output interface 710 (I / O), input device 712, and output device 714 may be omitted, and the device may function solely as a computer device within a network. Computer device 702 may 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 components described above together.

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

[0094] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), computer-readable storage media, and computer program products according to some embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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 processor to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processor, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0095] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processor to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions may also be loaded onto a computer or other programmable data processor, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable device for implementing the process. Figure 1a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0097] In a typical configuration, a computer device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0098] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0099] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by computer equipment. As defined in this application, computer-readable media does not include transient media, such as modulated data signals and carrier waves.

[0100] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0101] The embodiments of this application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The embodiments of this application can also be practiced in distributed computing environments where tasks are performed by remote processors connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0102] It should also be understood that, in the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0103] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0104] In the description of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this application, as well as the features of different embodiments or examples.

[0105] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for determining the crack initiation time and location based on DAS acoustic spectrum, characterized in that, include: Acquire DAS acoustic signals from the locations of distributed acoustic sensors; Generate a three-dimensional spectrum of the DAS acoustic signal; 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.

2. The method for determining the crack initiation time and location based on DAS acoustic spectrum as described in claim 1, characterized in that, The generation of the three-dimensional spectrum of the DAS acoustic signal includes: The DAS acoustic signal is subjected to noise reduction processing; The DAS acoustic signal obtained after noise reduction processing is downsampled; The downsampled DAS acoustic signal is converted into a DAS acoustic frequency domain signal. 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.

3. The method for determining the crack initiation time and location based on DAS acoustic spectrum as described in claim 2, characterized in that, The target time range is determined based on the initial pressure rise phase of the pressure curve for the corresponding fracturing stage.

4. The method for determining the crack initiation time and location based on DAS acoustic spectrum as described in claim 1, characterized in that, The specific frequency band includes frequency bands of not less than 2000Hz.

5. The method for determining the crack initiation time and location based on DAS acoustic spectrum as described in claim 1 or 4, characterized in that, The preset conditions include: The increase in power spectral density in a specific frequency band reaches the amplification threshold.

6. The method for determining the crack initiation time and location based on DAS acoustic spectrum as described in claim 5, characterized in that, The increase threshold includes a three-fold increase.

7. A device for determining the crack initiation time and location based on DAS acoustic spectrum, characterized in that, include: The acquisition module is used to acquire the DAS acoustic signal at the location of the distributed acoustic sensor; A generation module is used to generate a three-dimensional spectrum of the DAS acoustic signal; The determination module 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.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the computer program is run by the processor, it executes the instructions of the method according to any one of claims 1-6.

9. A computer storage medium having a computer program stored thereon, characterized in that, When the computer program is run by the processor of the computer device, it executes the instructions of the method according to any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when run by the processor of a computer device, executes instructions according to any one of claims 1-6.

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