A high sensitivity borehole fiber optic monitoring system and method

Abstract

The application discloses a high-sensitivity well optical fiber monitoring system and method, relates to the technical field of optical fiber logging, and comprises an excitation source module, an optical fiber acoustic sensor array and a signal demodulation processing module; the excitation source module is used for emitting an excitation acoustic signal so that the excitation acoustic signal propagates along a formation to the optical fiber acoustic sensor array arranged at a target position in a well; and the signal demodulation processing module is used for controlling the optical fiber acoustic sensor array to collect acoustic signals when the excitation acoustic signal propagates along the formation to the optical fiber acoustic sensor array, demodulating and analyzing the collected actual acoustic signals, and obtaining geological information on a propagation path of the excitation acoustic signal. The application can greatly improve the detection sensitivity of acoustic signals, and has the characteristics of simple structure, high reliability, high sensitivity and long detection distance due to the passive design in the well.

Description

Technical Field

[0001] This invention relates to the field of fiber optic logging technology, and in particular to a highly sensitive fiber optic monitoring system and method for wells. Background Technology

[0002] Old oilfields, developed for over ten years, have entered a "dual-high" development stage. The heterogeneity of the plane, inter-layer, intra-layer, and fluid processes has intensified, resulting in highly dispersed remaining oil, extremely complex oil-water relationships, and prominent issues of inefficient and ineffective water circulation, casing damage, and casing deformation. However, the remaining recoverable reserves remain considerable, with enormous potential. Old oilfields are the ballast of recoverable reserves and represent the highest quality reserve resources. By improving recovery rates, the full potential of old oilfields can be realized, leading to significant reserve increases.

[0003] Given the complex oil-water relationship in old oilfields and the dispersed nature of remaining and concealed oil and gas reservoirs, effectively identifying remaining oil and gas reservoirs and characterizing oil-water distribution has become a key aspect of the "ballast stone project" for old oilfields and one of the core elements for increasing oil and gas reserves and production.

[0004] In recent years, acoustic remote sensing, as a logging method, has not only been able to identify fractures and geological anomalies, compensating for the shallow detection limitations of imaging logging instruments, but has also played a role in identifying concealed oil and gas reservoirs and the distribution of remaining oil and gas reservoirs, achieving a detailed characterization of oil and gas reservoirs. As oil and gas reservoir exploration and development move towards deeper and ultra-deeper reservoirs, the operating environment for acoustic remote sensing instruments has become more demanding, requiring higher temperature resistance and pressure resistance. Simultaneously, smaller wellbore sizes necessitate further miniaturization of the instruments, increasing the complexity of acoustic remote sensing instruments based on traditional piezoelectric sensors (e.g., invention patents with publication number "CN118855449A" entitled "An Acoustic Logging Acoustic Remote Sensing Imaging Method, Equipment, Medium, and Product" and "CN102292518A" entitled "Well Monitoring Method Using Distributed Sensing Devices"), and reducing reliability. Therefore, traditional piezoelectric sensing acoustic wave remote detection instruments face the problems of "not being able to go down, inaccurate measurement, and discontinuous data", which can hardly meet the needs of remote detection. There is an urgent need for a monitoring technology that can withstand high temperature and high pressure, has a simple structure, high reliability, supports miniaturization and continuous data transmission to meet the detection needs of geological anomalies and cracks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology, and specifically provides a highly sensitive fiber optic monitoring system and method for underground wells, as detailed below:

[0006] 1) In a first aspect, the present invention provides a highly sensitive fiber optic monitoring system for underground wells, the specific technical solution of which is as follows:

[0007] It includes an excitation source module, an optical fiber acoustic sensor array, and a signal demodulation processing module.

[0008] The excitation source module is used to emit an excitation acoustic signal so that the excitation acoustic signal propagates along the formation to the fiber optic acoustic sensor array located at the target position downhole.

[0009] The signal demodulation and processing module is used to: control the fiber optic acoustic sensor array to collect acoustic signals when the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, demodulate and analyze the collected actual acoustic signals, and obtain geological information along the propagation path of the excitation acoustic signal.

[0010] The beneficial effects of the high-sensitivity fiber optic monitoring system for underground wells provided by this invention are as follows:

[0011] The fiber optic acoustic sensor array, after undergoing structural enhancement design, can greatly improve the detection sensitivity of acoustic signals. Moreover, the passive design adopted downhole features simple structure, high reliability, high sensitivity, and long detection distance.

[0012] Based on the above scheme, the high-sensitivity fiber optic monitoring system for wells of the present invention can be further improved as follows.

[0013] Furthermore, it also includes a synchronization control module, which is used to send the time of each excitation sound wave signal emitted by the excitation source module to the signal demodulation processing module whenever the excitation source module emits an excitation sound wave signal.

[0014] Furthermore, it also includes an optical fiber transmission system, through which the optical fiber acoustic wave sensor array transmits the collected actual acoustic wave signals to the signal demodulation and processing module.

[0015] Furthermore, the fiber optic acoustic wave sensor array transmits the collected actual acoustic wave signals to the fiber optic transmission system via a fiber optic auger.

[0016] Furthermore, the fiber optic acoustic sensor array is positioned at the target location downhole using a winch.

[0017] 2) Secondly, the present invention also provides a highly sensitive fiber optic monitoring method for underground wells, the specific technical solution of which is as follows:

[0018] The excitation source module emits an excitation acoustic signal, which propagates along the formation to the fiber optic acoustic sensor array located at the target position downhole.

[0019] When the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, the signal demodulation processing module controls the fiber optic acoustic sensor array to collect the acoustic signal. The collected actual acoustic signal is demodulated and analyzed to obtain geological information along the propagation path of the excitation acoustic signal.

[0020] Based on the above scheme, the high-sensitivity fiber optic monitoring method for wells of the present invention can be further improved as follows.

[0021] Furthermore, it also includes:

[0022] Whenever the excitation source module emits an excitation acoustic wave signal, the timing of each emission of the excitation acoustic wave signal is sent to the signal demodulation processing module via the synchronization control module.

[0023] Furthermore, the acquired actual acoustic wave signal is transmitted to the signal demodulation processing module, including:

[0024] The acquired actual acoustic wave signal is transmitted to the signal demodulation and processing module through an optical fiber transmission system.

[0025] Furthermore, it also includes:

[0026] The collected acoustic signals are transmitted to the fiber optic transmission system via a fiber optic motor head.

[0027] Furthermore, it also includes:

[0028] The fiber optic acoustic sensor array is positioned at the target location downhole using a winch.

[0029] It should be noted that the beneficial effects of the technical solution of the second aspect of the present invention and the corresponding possible implementation can be found in the above description of the technical effects of the first aspect and its corresponding possible implementation, and will not be repeated here. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below:

[0031] Figure 1 This is a schematic diagram of the structure of a high-sensitivity fiber optic monitoring system for underground wells according to an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the spectrum of the actual collected acoustic signal;

[0033] Figure 3 This is one of the flowcharts of a highly sensitive fiber optic monitoring method for underground wells according to an embodiment of the present invention;

[0034] Figure 4This is a second schematic flowchart of a highly sensitive fiber optic monitoring method for wells according to an embodiment of the present invention. Detailed Implementation

[0035] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0036] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0037] like Figure 1 As shown in the figure, a high-sensitivity well fiber optic monitoring system according to an embodiment of the present invention includes an excitation source module, a fiber optic acoustic sensor array, and a signal demodulation processing module.

[0038] The excitation source module is used to emit an excitation acoustic signal so that the excitation acoustic signal propagates along the formation to the fiber optic acoustic sensor array located at the target position downhole.

[0039] The excitation source module is a high-energy controllable high-repetition-frequency vibration source, but other excitation sources can also be selected according to actual conditions.

[0040] The signal demodulation and processing module is used to: control the fiber optic acoustic sensor array to collect acoustic signals when the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, demodulate and analyze the collected actual acoustic signals, and obtain geological information along the propagation path of the excitation acoustic signal.

[0041] On the ground, an electric spark source is used as the excitation source. Information such as voltage, frequency and interval are set. Through synchronous control, the excitation signal is released. At the same time, the signal demodulation and processing module obtains the information that the excitation source has started to release the excitation signal, triggering the acquisition system to collect the acoustic signal that has traveled through the strata and reached the fiber optic acoustic sensor array. Through further processing and analysis, the geological information along the propagation path of the acoustic signal can be obtained.

[0042] This involves removing noise and interference from the acquired acoustic signals to improve signal quality. This typically involves digital filtering techniques, which retain useful acoustic signals while removing unwanted background noise. By analyzing the time and speed of sound wave propagation, the depth and distance of the strata can be inferred. Sound waves encounter different stratum interfaces during underground propagation, resulting in reflection and refraction. By measuring the sound wave propagation time and combining it with the known sound wave speed, the depth of the stratum can be calculated. Different types of rocks and strata exhibit different propagation speeds and attenuation rates for sound waves. Therefore, by analyzing the waveform characteristics of the acquired acoustic signals, the properties and types of underground rocks can be understood. For example, waveform analysis can distinguish between different types of rocks such as sandstone and mudstone by comparing the extracted waveform features with known waveform features of different rock types. By comparing the differences in waveform features, the type of underground rock can be preliminarily determined. Furthermore, a large number of acoustic signals from known rock types can be collected, and their waveform features extracted to establish a waveform feature library. This library can serve as a reference for subsequent waveform analysis, using machine learning algorithms (such as support vector machines and neural networks) to classify and identify the waveform features. The algorithm is trained to accurately identify the waveform characteristics of different types of rocks. The identification results are compared with actual conditions to verify the algorithm's accuracy. If the identification results are inaccurate, the algorithm can be optimized and adjusted to improve the identification accuracy.

[0043] When performing waveform analysis, it is necessary to consider the impact of environmental factors on sound wave propagation, such as groundwater level and formation pressure. These factors may affect the propagation speed and attenuation of sound waves, thereby affecting the extraction and identification of waveform features. Specifically, their impact can be mitigated through the following methods:

[0044] 1) The first method: In acoustic signal analysis, it is first necessary to understand the propagation speed of sound waves in different media. This is done through experimental measurement or by consulting relevant literature to obtain the accurate propagation speed of sound waves in the target medium. Before waveform feature extraction, the acoustic signal is velocity-corrected to eliminate the influence of propagation speed on waveform characteristics.

[0045] 2) The second method: Utilize the relationship between the speed of sound propagation and propagation time to convert the sound wave signal from the time domain to the depth domain. This allows direct observation of the reflection of sound waves at different depths in the strata, thus enabling more accurate extraction of waveform features.

[0046] 3) The third method: Sound waves gradually attenuate during propagation due to absorption and scattering by the medium. By measuring the degree of attenuation at different distances, an attenuation compensation model can be established. Before waveform feature extraction, attenuation compensation is applied to the sound wave signal to restore the strength of the original signal.

[0047] 4) The fourth method: The frequency components of sound waves are also affected by attenuation during propagation. Spectral analysis can be used to observe the attenuation of different frequency components. Based on the spectral analysis results, different frequency components can be weighted to reduce the impact of attenuation on waveform characteristics.

[0048] Optionally, the signal demodulation processing module or other computer equipment can perform spectral analysis on the acquired actual acoustic signal to obtain its frequency distribution. Sound waves of different frequencies exhibit different attenuation characteristics when propagating underground. Therefore, spectral analysis can further reveal the structure and properties of underground strata. Based on the propagation path and reflection characteristics of the acquired actual acoustic signal, a structural map of the underground strata can be drawn. This helps in understanding the distribution, thickness, and morphology of the strata. By analyzing the waveform and spectral characteristics of the acquired actual acoustic signal, the properties of underground rocks, such as porosity and permeability, can be assessed.

[0049] The fiber optic acoustic wave sensor array is assembled from several fiber optic acoustic wave sensors, which can improve the sensitivity of acoustic wave acquisition. The spacing between the fiber optic acoustic wave sensors can be optimized according to actual detection needs to meet high-resolution well-to-surface detection. The fiber optic acoustic wave sensors are connected in series with optical fibers. The fiber optic acoustic wave sensors adopt a high-temperature resistant packaging design to meet the high-temperature environment downhole.

[0050] For example, ordinary single-mode optical fiber is wound with constant tension onto the outer surface of a 50mm diameter sensitizing structure, with 60 close-packed turns, and then encapsulated using high-temperature resistant materials to create an independent fiber optic acoustic wave sensor. The fiber optic acoustic wave sensor is then encapsulated into a fiber optic acoustic wave sensing array with a spacing of 20cm.

[0051] Optionally, the above technical solution also includes a synchronization control module, which is used to send the time of each excitation sound wave signal emitted by the excitation source module to the signal demodulation processing module whenever the excitation source module emits an excitation sound wave signal.

[0052] Optionally, the above technical solution also includes an optical fiber transmission system, through which the optical fiber acoustic wave sensor array transmits the collected actual acoustic wave signal to the signal demodulation processing module.

[0053] The fiber optic transmission system is made of optical-electric composite cable or optical cable, and can be designed to withstand high temperatures.

[0054] Each fiber optic acoustic sensor can also transmit the collected optical signal to the signal demodulation and processing module through the same transmission optical fiber. Each fiber optic acoustic sensor is connected to the communication optical fiber by fusion splicing or by patch cord plugging and unplugging.

[0055] Optionally, multiple fiber optic fusion splicing areas are determined, and a target laser of preset intensity is applied to the fiber optic fusion splicing areas using a laser. The preset intensity and the frequency of the target laser can be set according to the actual situation. The returned optical signal from the fiber optic fusion splicing area is collected, and the spectrum of the optical signal is converted into a spectral image. Multiple peaks, including the maximum peak, are marked at equal intervals in the spectral image. The equal interval can be understood as sampling points with equal intervals. Thus, multiple marked spectral images are obtained. A preset neural network model is trained using the multiple marked spectral images to obtain a trained preset neural network model. The trained preset neural network model is used to identify the maximum peak and multiple equally spaced peaks, including the maximum peak.

[0056] When different levels of fiber optic sensing units are connected by fiber optic fusion splicing, a target laser of preset intensity is applied to any actual fiber optic fusion splice area (the actual fiber optic fusion splice area refers to the fiber optic fusion splice area obtained when each fiber optic acoustic sensor and communication fiber is connected by fiber optic fusion splicing in this invention; the number of actual fiber optic fusion splice areas can be multiple) by a laser. The optical signal returned from the actual fiber optic fusion splice area is collected, and the spectrum of the optical signal is converted into a spectrum diagram. A pre-trained preset neural network model is used to identify the maximum peak value corresponding to the actual fiber optic fusion splice area and multiple equally spaced peak values, including the maximum peak value. The deviation between the maximum peak value corresponding to the actual fiber optic fusion splice area and the standard maximum peak value is calculated, as well as the deviation between the corresponding peak value corresponding to the actual fiber optic fusion splice area and the standard peak value. It is determined whether the proportion exceeding the preset deviation threshold exceeds the preset proportion threshold. If so, the fiber optic fusion splice is deemed unqualified; otherwise, it is deemed qualified.

[0057] Optionally, in the above technical solution, the fiber optic acoustic wave sensor array transmits the collected actual acoustic wave signal to the fiber optic transmission system through the fiber optic auger.

[0058] The headstock uses a high-temperature resistant optical fiber headstock, which has the ability to withstand high temperatures and pressure.

[0059] Optionally, in the above technical solution, the fiber optic acoustic sensor array is placed at the target location downhole using a winch.

[0060] Optionally, it also includes an adaptive push-fit system, which is used to achieve effective coupling between the optical signal collected by the fiber acoustic wave sensor array and the optical fiber receiving system. The adaptive push-fit system adopts a high temperature resistant adaptive design to meet the construction requirements of sleeves of different diameters.

[0061] The adaptive pushing system can preferably be an I-shaped spring plate, and the tension of the I-shaped spring plate can be set according to the actual situation.

[0062] The following embodiments illustrate a highly sensitive fiber optic monitoring system for underground wells according to the present invention:

[0063] like Figure 1 As shown, this example of a high-sensitivity well fiber optic monitoring system includes: an excitation source module, a fiber optic acoustic wave sensor array, a signal demodulation and processing module, a synchronization control module, a fiber optic transmission system, a fiber optic auger, and an adaptive push-and-hold system. The excitation source module emits an excitation acoustic wave signal that propagates along the formation. The excitation source signal propagating along the formation is captured by the downhole fiber optic sensor array. When the excitation acoustic wave signal propagates along the formation to the fiber optic acoustic wave sensor array, the signal demodulation and processing module controls the fiber optic acoustic wave sensor array to collect the acoustic wave signal. The collected actual acoustic wave signal and the excitation acoustic wave signal are demodulated and analyzed to obtain geological information along the propagation path of the excitation acoustic wave signal. The collected actual acoustic wave signal is shown in the figure below. Figure 2 As shown.

[0064] This invention achieves high-sensitivity signal detection by enhancing the sensitivity of fiber optic acoustic wave sensors (by increasing the change in the length of the acoustically induced fiber; the greater the change, the higher the sensitivity). It achieves high-resolution data acquisition through short-range arraying of the fiber optic acoustic wave sensors. An adaptive push-and-pull system effectively couples weak excitation signals propagating long distances through the formation with the fiber optic acoustic wave sensors. The integration of fiber optic signal transmission and sensing enables high-speed, high-capacity transmission of the system's sensing signals. This invention features simple structure, high reliability, high sensitivity, high resolution, large-scale array multiplexing, and support for real-time high-speed data transmission. It can be used for the refined identification of geological anomalies and fractures in the "ballast stone project" of old oilfields. Figure 3 As shown in the figure, a highly sensitive fiber optic monitoring method for underground wells according to an embodiment of the present invention includes the following steps:

[0065] S1. An excitation acoustic signal is emitted through the excitation source module, so that the excitation acoustic signal propagates along the formation to the fiber optic acoustic sensor array set at the target location downhole.

[0066] S2. When the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, the signal demodulation processing module controls the fiber optic acoustic sensor array to collect the acoustic signal. The collected actual acoustic signal is demodulated and analyzed to obtain the geological information along the propagation path of the excitation acoustic signal.

[0067] Optionally, the above technical solution also includes:

[0068] Whenever the excitation source module emits an excitation acoustic wave signal, the timing of each emission of the excitation acoustic wave signal is sent to the signal demodulation processing module via the synchronization control module.

[0069] Optionally, in the above technical solution, the acquired actual acoustic wave signal is transmitted to the signal demodulation processing module, including:

[0070] The acquired actual acoustic wave signal is transmitted to the signal demodulation and processing module through an optical fiber transmission system.

[0071] Optionally, the above technical solution also includes:

[0072] The collected acoustic signals are transmitted to the fiber optic transmission system via a fiber optic motor head.

[0073] Optionally, the above technical solution also includes:

[0074] The fiber optic acoustic sensor array is positioned at the target location downhole using a winch.

[0075] In another embodiment, such as Figure 4 As shown, a highly sensitive fiber optic monitoring method for underground wells according to the present invention includes the following steps:

[0076] S11. Connect the fiber optic acoustic wave sensor array on the ground to form a downhole acquisition system;

[0077] S12. The top of the fiber optic sensor array is connected to the fiber optic motor head, and the other end of the fiber optic motor head is connected to the fiber optic transmission system.

[0078] S13, The other end of the fiber optic transmission system is connected to the ground signal demodulation and processing module;

[0079] S14. Use a winch to lower the fiber optic acoustic wave sensor array to the target position in the well.

[0080] S15. Turn on the excitation source module and set parameters such as excitation voltage and frequency;

[0081] S16. Open the signal demodulation processing module and set parameters such as laser current, power, and frequency;

[0082] S17. Open the synchronization control module and control the excitation source module to release the excitation signal;

[0083] S18. The downhole fiber optic acoustic array sensor receives the excitation signal propagating through the formation and transmits it to the surface signal demodulation and processing module via the fiber optic transmission system.

[0084] S19, the ground signal demodulation and processing module demodulates and analyzes the acquired actual acoustic signals to identify underground geological anomalies and obtain geological information along the propagation path of the excitation acoustic signals.

[0085] In the above embodiments, although the steps are numbered S1, S2, etc., they are only specific embodiments given by the present invention. Those skilled in the art can adjust the execution order of S1, S2, etc. according to the actual situation, which is also within the protection scope of the present invention. It can be understood that in some embodiments, some or all of the above embodiments may be included.

[0086] It should be noted that the beneficial effects of the high-sensitivity well fiber optic monitoring method provided in the above embodiments are the same as those of the high-sensitivity well fiber optic monitoring system described above, and will not be repeated here. Furthermore, the method and system embodiments provided in the above embodiments belong to the same concept, and their specific implementation processes are detailed in the method embodiments, and will not be repeated here.

[0087] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0088] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0089] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A highly sensitive fiber optic monitoring system for underground wells, characterized in that, It includes an excitation source module, an optical fiber acoustic sensor array, and a signal demodulation processing module; The excitation source module is used to: emit an excitation acoustic signal so that the excitation acoustic signal propagates along the formation to the fiber optic acoustic sensor array set at the target location downhole; The signal demodulation processing module is used to: control the fiber optic acoustic sensor array to collect acoustic signals when the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, demodulate and analyze the collected actual acoustic signals, and obtain geological information along the propagation path of the excitation acoustic signal.

2. The high-sensitivity fiber optic monitoring system for underground wells according to claim 1, characterized in that, It also includes a synchronization control module, which is used to send the time of each excitation sound wave signal emitted by the excitation source module to the signal demodulation processing module whenever the excitation source module emits an excitation sound wave signal.

3. A high-sensitivity fiber optic monitoring system for underground wells according to claim 1 or 2, characterized in that, It also includes an optical fiber transmission system, through which the optical fiber acoustic wave sensor array transmits the collected actual acoustic wave signals to the signal demodulation processing module.

4. The high-sensitivity fiber optic monitoring system for underground wells according to claim 3, characterized in that, The fiber optic acoustic sensor array transmits the collected acoustic signals to the fiber optic transmission system via a fiber optic auger.

5. A high-sensitivity fiber optic monitoring system for underground wells according to claim 1 or 2, characterized in that, The fiber optic acoustic sensor array is positioned at the target location downhole using a winch.

6. A highly sensitive fiber optic monitoring method for underground wells, characterized in that, include: The excitation source module emits an excitation acoustic signal, which propagates along the formation to the fiber optic acoustic sensor array located at the target position downhole. When the excitation acoustic signal propagates along the strata to the fiber optic acoustic sensor array, the signal demodulation processing module controls the fiber optic acoustic sensor array to collect the acoustic signal, demodulates and analyzes the collected actual acoustic signal, and obtains the geological information along the propagation path of the excitation acoustic signal.

7. The highly sensitive fiber optic monitoring method for underground wells according to claim 6, characterized in that, Also includes: Whenever the excitation source module emits an excitation acoustic wave signal, the timing of each emission of the excitation acoustic wave signal is sent to the signal demodulation processing module via the synchronization control module.

8. A highly sensitive fiber optic monitoring method for underground wells according to claim 6 or 7, characterized in that, The acquired actual acoustic wave signal is transmitted to the signal demodulation processing module, including: The acquired actual acoustic wave signal is transmitted to the signal demodulation and processing module through an optical fiber transmission system.

9. The highly sensitive fiber optic monitoring method for underground wells according to claim 8, characterized in that, Also includes: The collected acoustic signals are transmitted to the optical fiber transmission system via an optical fiber optic motor head.

10. A highly sensitive fiber optic monitoring method for underground wells according to claim 6 or 7, characterized in that, Also includes: The fiber optic acoustic sensor array is positioned at the target location downhole using a winch.

Images