Optical fiber monitoring and early warning experimental device and method for stratum settlement in ultra-deep water environment

Abstract

The invention relates to an optical fiber monitoring and early warning experimental device and method for stratum settlement in an ultra-deep water environment, and the device comprises a stratum and oil gas collection environment simulation system which is used for reconstructing the ultra-deep water environment and oil / gas production conditions, inducing the settlement behavior of a deep water stratum, and providing repeatable and comparable test scenes and boundary conditions; the optical fiber monitoring system is used for realizing strong coupling of an optical fiber and a soil body, obtaining a strain / temperature field along the depth, completing temperature-strain decoupling and coupling quality self-diagnosis, and providing high signal-to-noise ratio data to the downstream; and the data processing and linkage control system is used for fusing and cleaning multi-source data, inverting the settlement rate in real time, evaluating the risk, performing linkage adjustment on the stratum and oil gas acquisition environment simulation system according to a predetermined risk grade division strategy, triggering alarm and protection, and generating a test record and a parameterized report at the same time. And a'loading-monitoring-processing-control 'closed-loop system is formed. The method can be widely applied to the technical field of ocean engineering and geotechnical engineering monitoring.

Description

Technical Field

[0001] This invention relates to the field of marine engineering and geotechnical engineering monitoring technology, and in particular to an experimental device and method for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments. Background Technology

[0002] With the continuous development of marine oil and gas resources, deep-sea minerals, and subsea infrastructure, engineering construction is gradually extending to deep-water and ultra-deep-water areas. In this process, geological disasters such as ground subsidence, soft soil consolidation, and submarine landslides frequently occur, which may lead to uneven settlement, instability, or even damage to key structures such as subsea pipelines, drilling risers, and offshore platform foundations, seriously threatening the safety and lifespan of deep-sea engineering projects.

[0003] Currently, monitoring of deep-water and ultra-deep-water ground subsidence mainly relies on traditional leveling, acoustic positioning, or limited mechanical sensing devices. These methods generally suffer from problems such as difficulty in deployment, limited applicable water depth, insufficient accuracy, and poor real-time performance, making it particularly difficult to achieve long-term, continuous, and large-scale monitoring in ultra-deep-water environments.

[0004] Recently, fiber optic sensing technology has been increasingly applied to soil displacement monitoring and structural health diagnosis due to its advantages such as resistance to electromagnetic interference, long-distance transmission capability, high sensitivity, and the ability to achieve distributed monitoring. However, existing fiber optic monitoring systems are mostly designed for land or shallow water environments, lacking complete solutions adapted to ultra-deep water, high pressure, high corrosion, and complex operating conditions. Furthermore, current research is still incomplete in integrating settlement monitoring with early warning systems, making it difficult to achieve a closed-loop process from data acquisition and real-time analysis to risk classification and early warning. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an experimental device and method for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments. This invention solves the problem of inaccurate monitoring and real-time early warning of ground subsidence in ultra-deep water environments in existing technologies, and realizes high-precision subsidence monitoring and risk classification early warning based on fiber optic sensing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments, comprising: Formation and oil and gas extraction environment simulation system, fiber optic monitoring system, and data processing and linkage control system; The formation and oil and gas extraction environment simulation system is used to reconstruct the ultra-deepwater environment and oil / gas extraction conditions, induce deepwater formation subsidence behavior, and provide repeatable and comparable test scenarios and boundary conditions. The fiber optic monitoring system is used to achieve strong coupling between the fiber optic cable and the soil and obtain the strain / temperature field along the depth, complete temperature-strain decoupling and coupling quality self-diagnosis, and provide high signal-to-noise ratio data to the downstream. The data processing and linkage control system is used to integrate and clean multi-source data, invert the settlement rate in real time and assess the risk, and adjust the formation and oil and gas acquisition environment simulation system according to the predetermined risk level classification strategy, trigger alarms and protection, and generate test records and parameterized reports to form a closed-loop system of "loading-monitoring-processing-control".

[0007] Furthermore, the formation and oil and gas extraction environment simulation system includes a high-temperature and high-pressure test chamber, a bottom injection and production zone, and a simulated formation medium. The high temperature and high pressure test chamber is used to provide controllable geological and temperature and pressure environmental conditions that conform to real working conditions, based on the control signals of the data processing and linkage control system. The simulated formation medium is set inside the high temperature and high pressure test chamber and includes several formations formed by layering media with different stiffness / permeability, used to reproduce differential settlement, interlayer slip and formation collapse; The bottom injection-production zone is located in the lowest layer of medium to simulate the reservoir in an ultra-deepwater environment, and injects / extracts fluid according to the control signals of the data processing and linkage control system to induce deepwater formation subsidence behavior.

[0008] Furthermore, the fiber optic monitoring system includes a sensing fiber assembly and an expansion anchoring unit; The sensing fiber optic assembly is used to sense temperature and strain changes in different geological strata. The expansion anchoring unit is used to tightly fix different segments of the sensing optical fiber assembly in the predetermined stratum, increasing the coupling with the stratum, while enhancing the bearing capacity of the stratum and reducing stratum deformation or cracks caused by settlement.

[0009] Furthermore, the sensing fiber assembly includes a strain sensing fiber, a temperature sensing fiber, and a polyethylene protective tube; The strain-sensing optical fiber is used to sense strain changes in the formation. The temperature sensing fiber is used to detect temperature changes in the strata and eliminate the influence of temperature changes on subsidence data. The polyethylene protective tube is disposed outside the strain sensing fiber and the temperature sensing fiber, and a buffer creeping layer is disposed outside the polyethylene protective tube to improve the coupling with the stratum and ensure that the strain sensing fiber and the temperature sensing fiber can work stably in the extreme deep-sea environment.

[0010] Furthermore, the data processing and linkage control system includes an optical fiber umbilical cable, an optical fiber demodulator, a data transmission line, a computer, and an injection and acquisition controller; The optical fiber umbilical cable is used to transmit the optical signals emitted by the strain sensing fiber and the temperature sensing fiber to the optical fiber demodulator. The fiber optic demodulator is used to demodulate the optical signal into a digital signal and transmit it to the computer through the data transmission line. The computer is used to process the received data, perform settlement / rate inversion and risk assessment, generate curves, reports and records, and link production restriction and pressure reduction control according to the real-time acquired settlement rate and the predetermined risk level classification strategy. It also sends adjustment commands to the injection and production controller through the data transmission line to simulate triggering alarms and protection. The injection and production controller is used to realize controllable injection and production in the bottom injection and production area, control the pump valves according to the set strategy, track the pressure / flow setting in a closed loop, and realize the release-back pressure procedure.

[0011] Furthermore, the computer is equipped with a data processing module, a risk level classification module, and a coordinated production restriction and pressure reduction control module; The data processing module is used to perform noise reduction, temperature-strain coupling, and formation subsidence inversion on the received digital signal to obtain the formation subsidence rate. The risk level classification module is used to assess and classify the current stratum subsidence rate according to a preset risk level classification strategy. The coordinated production restriction and pressure reduction control module is used to generate corresponding coordinated production restriction and pressure reduction control commands based on risk assessment and classification results.

[0012] Furthermore, the risk level classification module uses time and cumulative settlement depth as indicators, combined with the average daily settlement rate, to classify the risk level into three alarm levels: yellow, orange, and red. A yellow alert indicates that the settlement exceeds the forecast but is still controllable, corresponding to a daily average rate greater than 2 mm / day, or a cumulative settlement exceeding "2t+5mm", where t is time in days; An orange alert indicates that the settlement rate and cumulative amount deviate significantly from the normal settlement range, corresponding to a daily average rate greater than 5 mm / day, or a cumulative settlement exceeding "5t+10 mm"; A red alert indicates that ground subsidence has entered a danger zone, posing structural or functional risks, and requires immediate emergency response. This corresponds to a daily average subsidence rate greater than 10 mm / day, or a cumulative subsidence exceeding "10t+15mm".

[0013] Furthermore, the coordinated production restriction and pressure reduction control module generates corresponding coordinated production restriction and pressure reduction control commands based on risk assessment and classification results, including: When a yellow alarm is detected, a daily production limit is set for the injection-production controller, and the collection rate of the bottom injection-production zone is reduced according to the preset step size. At the same time, formation pressure maintenance measures are assessed / prepared. When an orange alarm is detected, production is limited or stopped for the injection-production controller, and the preset pressure drop slope limit and daily production slope limit are enforced. At the same time, formation pressure maintenance measures are initiated in the bottom injection-production area to control formation-scale pressure drop. When the computer determines that a red alarm has been triggered, the injection and production controller will be shut down, and short-term backpressure / water injection will be performed when conditions permit to mitigate the settling rate.

[0014] Furthermore, the experimental apparatus also includes a timer and a camera, the timer being used to record the loading time under the working condition; and the camera being used to observe the ground subsidence state.

[0015] Secondly, the present invention provides a method for an experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments, comprising: The simulation environment and operating conditions were determined according to the experimental requirements, and the formation and oil and gas extraction environment simulation system was filled with layered media. After the formation in the formation and oil and gas extraction environment simulation system is stabilized, the fiber optic monitoring system will be deployed. Connect the formation and oil and gas extraction environment simulation system, the fiber optic monitoring system, and the data processing and linkage control system, and check them to ensure that the experimental device can be used normally. The data processing and linkage control system controls the bottom layer and oil and gas extraction environment simulation system, enabling it to simulate the oil / gas extraction conditions in the required ultra-deep water environment, and continuously collects strain and temperature data streams through the fiber optic monitoring system. Based on the collected data, the formation subsidence rate is calculated to provide different risk warnings, and corresponding linkage production restriction and pressure reduction measures are taken. The actions and curves in the process are automatically recorded, parameterized reports are generated and data is backed up, and the entire process is analyzed and summarized after the experimental cycle ends. By changing the simulated environment and operating conditions, and repeating all the above steps, the impact of oil and gas extraction on formation subsidence under different environments and operating conditions was analyzed.

[0016] The present invention has the following advantages due to the adoption of the above technical solutions: 1. This invention integrates the fiber optic monitoring system, the formation and oil and gas acquisition environment simulation system, and the data processing and linkage control system into a closed-loop system of "loading-monitoring-processing-control", thus avoiding the problem of the separation between monitoring and operating conditions in the prior art.

[0017] 2. This invention, through the combination of a high-temperature and high-pressure test chamber, a bottom injection and production zone, and A / B / C layered media, can reconstruct an ultra-deepwater environment in the laboratory and superimpose different injection and production controller operations to simulate real-world constant pressure / constant flow / step release-back pressure and other working conditions, thereby achieving controllable reproduction and comparison of formation subsidence-induced deformation.

[0018] 3. This invention constructs a risk level classification strategy based on settlement rate and implements yellow / orange / red graded early warning, which corresponds one-to-one with injection and production actions, realizing a closed-loop system of "early warning - handling - verification" on the same platform. It provides a portable calibration and strategy optimization basis for field applications, and can directly support the setting of settlement threshold and the optimization of injection and production strategies, thereby improving the monitoring and risk management level of deepwater oil and gas development process.

[0019] Therefore, this invention can be widely applied in the field of marine engineering and geotechnical engineering monitoring technology. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of an experimental device for monitoring and early warning of ground subsidence in an ultra-deep water environment, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the optical fiber monitoring system provided in an embodiment of the present invention; Figure 3 This is a flowchart of the data processing and linkage control process provided in the embodiments of the present invention.

[0021] The labels for the attached figures are as follows: 1. Sensor fiber optic assembly; 101. Strain sensing fiber optic cable; 102. Temperature sensing fiber optic cable; 103. Polyethylene protective tube; 2. Expansion anchoring unit; 3. Fiber optic umbilical cable; 4. Fiber optic demodulator; 5. Data transmission line; 6. Computer; 7. Bottom injection-production zone; 8. Simulated formation medium (A / B / C stratification); 9. Injection-production pipeline; 10. Injection-production controller; 11. High temperature and high pressure test chamber; 12. Chamber inlet; 13. Chamber outlet; 14. Temperature controller; 15. Pressure controller. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Existing technologies for monitoring ground subsidence in ultra-deep water environments primarily rely on traditional measurement or limited sensing devices, which suffer from problems such as difficult deployment, limited applicable water depth, poor real-time performance, and difficulty in providing early warnings. This leads to difficulties in timely detection and accurate assessment of subsidence risks. In some embodiments of this invention, a fiber optic monitoring and early warning experimental device for ground subsidence in ultra-deep water environments is provided. This device integrates a ground and oil and gas extraction environment simulation system, a fiber optic monitoring system, and a data processing and linkage control system, constructing a closed-loop system of "loading-monitoring-processing-control." This system enables precise measurement and data processing of ground subsidence and provides graded early warnings based on risk levels. This invention can operate stably for extended periods in complex environments with high pressure and strong corrosion, achieving precise measurement and real-time early warning of ground subsidence, thus providing effective protection for the safe operation of deep-sea engineering projects.

[0025] Correspondingly, in other embodiments of the present invention, an experimental method for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments is provided.

[0026] Example 1 like Figure 1 As shown, this invention provides an experimental device for fiber optic monitoring and early warning of formation subsidence in ultra-deepwater environments. It includes a formation and oil / gas extraction environment simulation system, a fiber optic monitoring system, and a data processing and linkage control system. The formation and oil / gas extraction environment simulation system reconstructs the ultra-deepwater environment and oil / gas extraction conditions, induces deepwater formation subsidence behavior, and provides repeatable and comparable test scenarios and boundary conditions. The fiber optic monitoring system achieves strong coupling between the fiber and the soil and obtains the strain / temperature field along the depth, completes temperature-strain decoupling and coupling quality self-diagnosis, and provides high signal-to-noise ratio data downstream for the inversion of subsidence curves and subsidence rates / accelerations. The data processing and linkage control system fuses and cleans multi-source data, inverts subsidence rates in real time, assesses risks, and, according to a predetermined risk level classification strategy, adjusts the formation and oil / gas extraction environment simulation system, triggers alarms and protection mechanisms, and simultaneously generates test records and parameterized reports, forming a closed-loop system of "loading-monitoring-processing-control".

[0027] Furthermore, the formation and oil and gas extraction environment simulation system mainly includes a high-temperature and high-pressure test chamber 11, a bottom injection-production zone 7, and a simulated formation medium 8. The high-temperature and high-pressure test chamber 11 provides controllable formation and temperature / pressure environmental conditions that conform to real-world operating conditions, based on control signals from the data processing and linkage control system. The simulated formation medium 8 is located within the high-temperature and high-pressure test chamber 11 and includes formations A, B, and C, formed by layering media of different stiffness / permeability from top to bottom, used to reproduce differential settlement, interlayer slip, and formation collapse. The bottom injection-production zone 7 is located in the lowest layer of medium (i.e., formation C) and is used to simulate reservoirs in ultra-deepwater environments, injecting / extracting fluids according to control signals from the data processing and linkage control system to induce deepwater formation settlement behavior.

[0028] In this embodiment, the formation and oil and gas extraction environment simulation system can replace soil with different parameters as the simulated formation medium (A / B / C layering) according to the simulation purpose, so as to realize oil and gas extraction under different formation conditions.

[0029] Furthermore, the high-temperature and high-pressure test chamber 11 is provided with a chamber inlet 12 at the top for media supply and connection, allowing the injection and replenishment of test media (such as formation / liquid) into the high-temperature and high-pressure test chamber 11 before the test to establish different preset working conditions; the high-temperature and high-pressure test chamber 11 is provided with a chamber outlet 13 at the bottom for connection to the discharge / recovery pipeline, allowing the discharge or recovery of the test media in the high-temperature and high-pressure test chamber 11, and can be used for sampling and / or post-test processing; the high-temperature and high-pressure test chamber 11 is also provided with a temperature controller 14 and a pressure controller 15, which are used to collect and control the temperature and pressure in the high-temperature and high-pressure test chamber 11, respectively.

[0030] Furthermore, such as Figure 2 As shown, the fiber optic monitoring system mainly includes a sensing fiber assembly 1 and an expansion anchoring unit 2. The sensing fiber assembly 1 is the core sensing component of the fiber optic monitoring system, used to sense changes in soil temperature and strain. The expansion anchoring unit 2 is used to tightly fix different sections of the sensing fiber assembly 1 into the predetermined soil layer, increasing the coupling with the soil layer, enhancing the bearing capacity of the soil or soil layer, and reducing soil deformation or cracking caused by settlement.

[0031] Furthermore, the sensing fiber assembly 1 includes a strain sensing fiber 101, a temperature sensing fiber 102, and a polyethylene protective tube 103; the strain sensing fiber 101 is used to sense strain changes in the stratum (such as tension or compression), and can reflect physical changes such as stratum subsidence and displacement in real time; the temperature sensing fiber 102 is used to sense temperature changes in the stratum, eliminating the influence of temperature on subsidence data; the polyethylene protective tube 103 is disposed outside the strain sensing fiber 101 and the temperature sensing fiber 102, and a buffer crawling layer (spiral groove) is also disposed outside the polyethylene protective tube 103 to improve coupling with the stratum and ensure that the strain sensing fiber 101 and the temperature sensing fiber 102 can work stably in extreme deep-sea environments.

[0032] In this embodiment, the purpose of the temperature sensing fiber 102 is to combine the effect of thermal expansion or contraction of the strain sensing fiber 101 caused by temperature to correct the signal of the strain sensing fiber 101, thereby ensuring the accuracy of the optical signal. The polyethylene protective tube has excellent corrosion resistance, sealing properties, and strength, which can prevent the strain sensing fiber and the temperature sensing fiber from being damaged by external physical forces and corroded by seawater.

[0033] Furthermore, such as Figure 3 As shown, the data processing and linkage control system mainly includes an optical fiber umbilical cable 3, an optical fiber demodulator 4, a data transmission line 5, a computer 6, and an injection-production controller 10. The optical fiber umbilical cable 3 transmits the optical signals emitted by the strain sensing fiber 101 and temperature sensing fiber 102 in the sensing fiber assembly 1 to the optical fiber demodulator 4. The optical fiber demodulator 4 demodulates the optical signals into digital signals and transmits them to the computer 6 via the data transmission line 5. The computer 6 undertakes important tasks such as data storage, processing, analysis, and visualization; performs sedimentation / rate inversion and risk assessment; generates curves, reports, and records; and, based on the real-time acquired sedimentation rate and predetermined risk level classification strategy, implements linkage control such as production restriction and pressure reduction. It sends adjustment commands to the injection-production controller 10 via the data transmission line 5, simulating alarm and protection triggers. The injection-production controller 10 realizes controllable injection and production in the bottom injection-production zone 7, controls pumps and valves according to a set strategy, tracks pressure / flow settings in a closed loop, and implements a release-backpressure procedure.

[0034] Furthermore, the fiber optic umbilical cable 3 uses single-mode fiber, which has lower signal attenuation and higher transmission bandwidth.

[0035] Furthermore, the computer is equipped with a data processing module, a risk level classification module, and a coordinated production restriction and pressure reduction control module. The data processing module performs noise reduction, temperature-strain coupling, and formation subsidence inversion on the received digital signals to obtain the formation subsidence rate. The risk level classification module assesses and classifies the current formation subsidence rate according to a preset risk level classification strategy. The coordinated production restriction and pressure reduction control module generates corresponding coordinated production restriction and pressure reduction control commands based on the risk assessment and classification results.

[0036] Furthermore, the risk level classification module includes a three-level alarm system: yellow, orange, and red. The risk level classification rules use time t (day) and cumulative settlement depth h (mm) as indicators, combined with the average daily settlement rate, to make a judgment. The specific three-level alarm classification rules are as follows: A yellow alert indicates that settlement exceeds prediction but is still manageable. This corresponds to a daily average settlement rate greater than approximately 2 mm / day, or a cumulative settlement exceeding "2t + 5 mm".

[0037] An orange alert indicates that the settlement rate and cumulative amount deviate significantly from the normal settlement range. This corresponds to a rate greater than approximately 5 mm / day, or a cumulative settlement exceeding "5t + 10 mm".

[0038] A red alert indicates that ground subsidence has entered a danger zone, posing a structural or functional risk, and requires immediate emergency response. This corresponds to a subsidence rate greater than approximately 10 mm / day, or a cumulative subsidence exceeding "10t + 15 mm".

[0039] Furthermore, in the coordinated production restriction and voltage reduction control module, the coordinated production restriction and voltage reduction controls include: When a yellow alarm is detected, a daily production limit is set for the injection-production controller, and the collection rate in the bottom injection-production zone is reduced; and formation pressure maintenance measures such as water injection or back pressure are assessed / prepared. When an orange alarm is detected, production is limited or stopped for the injection and production controller, and stricter pressure drop slope and daily production slope limits are enforced. Water injection, backpressure, and gas cap reinjection are initiated in the bottom injection and production area to control formation-scale pressure drop. When the computer determines that a red alarm has been triggered, the injection and production controller will be shut down, and short-term backpressure / water injection will be performed when conditions permit to mitigate the settling rate.

[0040] Furthermore, the experimental apparatus of the present invention also includes a timer and a camera, wherein the timer is used to record the loading time of the working condition; and the camera is used to observe the settlement state of the strata to ensure the rationality of the working condition.

[0041] Example 2 Based on the experimental device for monitoring and early warning of ground subsidence in ultra-deep water environment provided in Embodiment 1, this embodiment provides an experimental method for monitoring and early warning of ground subsidence in ultra-deep water environment, including the following steps: Step 1: Determine the simulation environment and operating conditions according to the experimental requirements, and fill the formation and oil and gas extraction environment simulation system with layered media; Step 2: After the formation in the formation and oil and gas extraction environment simulation system has stabilized, the fiber optic monitoring system will be deployed. Step 3: Connect the formation and oil and gas extraction environment simulation system, the fiber optic monitoring system, and the data processing and linkage control system, and check them to ensure that the experimental device can be used normally. Step 4: Control the bottom layer and oil and gas extraction environment simulation system through the data processing and linkage control system, so that it can simulate the oil / gas extraction conditions in the required ultra-deep water environment, and continuously collect strain and temperature data streams through the fiber optic monitoring system. Step 5: Calculate the formation subsidence rate based on the collected data to issue different risk warnings, and take corresponding coordinated production restriction and pressure reduction measures. Automatically record the actions and curves during the process, generate parameterized reports and back up the data. After the experimental cycle is completed, analyze and summarize the entire process. Step Six: Change the simulated environment and operating conditions, and repeat steps one through five above to analyze the impact of oil and gas extraction on formation subsidence under different environments and operating conditions.

[0042] Furthermore, in step one above, the layered filling of the formation and oil and gas extraction environment simulation system mainly refers to filling different formation media into layers in the high temperature and high pressure test chamber 11, and setting up the bottom injection and production zone 7 in the bottom layer of the media.

[0043] Furthermore, in step two above, setting up the fiber optic monitoring system mainly refers to: placing the sensing fiber optic assembly 1 at a preset position in the preset stratum, and waiting for the expansion anchoring unit 2 to solidify at the set position for a specified time, so that the fiber optic monitoring system is fully coupled with the simulated stratum medium (A / B / C layers).

[0044] Furthermore, in step three above, the connection and inspection mainly refer to: connecting the sensing fiber optic assembly 1 to the fiber optic demodulator 4 via the fiber optic umbilical cable 3, and connecting the fiber optic demodulator 4 to the computer 6 via the data transmission line 5; connecting the temperature controller and pressure controller to the computer 6 via the data transmission line 5; and connecting the injection and extraction controller 10 to the computer 6 via the data transmission line 5. This enables the computer to receive the temperature and stress changes output by the sensing fiber optic assembly 1, and the injection and extraction controller to accurately control the internal pressure of the bottom injection and extraction zone 7.

[0045] Furthermore, in step four above, the control of the bottom layer and oil and gas extraction environment simulation system through the data processing and linkage control system mainly refers to: sealing the high temperature and high pressure test chamber 11, setting the temperature controller 14 and pressure controller 15 to the predetermined temperature and pressure through the computer 6, and starting the formal experiment after stabilization; setting and loading the injection and production controller 10 through the computer 6 to simulate the oil / gas production conditions in the ultra-deep water environment.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments, characterized in that, include: Formation and oil and gas extraction environment simulation system, fiber optic monitoring system, and data processing and linkage control system; The formation and oil and gas extraction environment simulation system is used to reconstruct the ultra-deepwater environment and oil / gas extraction conditions, induce deepwater formation subsidence behavior, and provide repeatable and comparable test scenarios and boundary conditions. The fiber optic monitoring system is used to achieve strong coupling between the fiber optic cable and the soil and obtain the strain / temperature field along the depth, complete temperature-strain decoupling and coupling quality self-diagnosis, and provide high signal-to-noise ratio data to the downstream. The data processing and linkage control system is used to integrate and clean multi-source data, invert the settlement rate in real time and assess the risk, and adjust the formation and oil and gas acquisition environment simulation system according to the predetermined risk level classification strategy, trigger alarms and protection, and generate test records and parameterized reports to form a closed-loop system of "loading-monitoring-processing-control".

2. The experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environment as described in claim 1, characterized in that, The formation and oil and gas extraction environment simulation system includes a high-temperature and high-pressure test chamber, a bottom injection and production zone, and a simulated formation medium. The high temperature and high pressure test chamber is used to provide controllable geological and temperature and pressure environmental conditions that conform to real working conditions, based on the control signals of the data processing and linkage control system. The simulated formation medium is set inside the high temperature and high pressure test chamber and includes several formations formed by layering media with different stiffness / permeability, used to reproduce differential settlement, interlayer slip and formation collapse; The bottom injection-production zone is located in the lowest layer of medium to simulate the reservoir in an ultra-deepwater environment, and injects / extracts fluid according to the control signals of the data processing and linkage control system to induce deepwater formation subsidence behavior.

3. The experimental device for fiber optic monitoring and early warning of ground subsidence in an ultra-deep water environment as described in claim 2, characterized in that, The fiber optic monitoring system includes a sensing fiber optic assembly and an expansion anchoring unit. The sensing fiber optic assembly is used to sense temperature and strain changes in different geological strata. The expansion anchoring unit is used to tightly fix different segments of the sensing optical fiber assembly in the predetermined stratum, increasing the coupling with the stratum, while enhancing the bearing capacity of the stratum and reducing stratum deformation or cracks caused by settlement.

4. The experimental device for fiber optic monitoring and early warning of ground subsidence in an ultra-deep water environment as described in claim 3, characterized in that, The sensing fiber assembly includes a strain sensing fiber, a temperature sensing fiber, and a polyethylene protective tube. The strain-sensing optical fiber is used to sense strain changes in the formation. The temperature sensing fiber is used to detect temperature changes in the strata and eliminate the influence of temperature changes on subsidence data. The polyethylene protective tube is disposed outside the strain sensing fiber and the temperature sensing fiber, and a buffer creeping layer is disposed outside the polyethylene protective tube to improve the coupling with the formation and ensure that the strain sensing fiber and the temperature sensing fiber can work stably in the extreme deep-sea environment.

5. The experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environment as described in claim 4, characterized in that, The data processing and linkage control system includes an optical fiber umbilical cable, an optical fiber demodulator, a data transmission line, a computer, and an injection and acquisition controller. The optical fiber umbilical cable is used to transmit the optical signals emitted by the strain sensing fiber and the temperature sensing fiber to the optical fiber demodulator. The fiber optic demodulator is used to demodulate the optical signal into a digital signal and transmit it to the computer through the data transmission line. The computer is used to process the received data, perform settlement / rate inversion and risk assessment, generate curves, reports and records, and link production restriction and pressure reduction control according to the real-time acquired settlement rate and the predetermined risk level classification strategy. It also sends adjustment commands to the injection and production controller through the data transmission line to simulate triggering alarms and protection. The injection and production controller is used to realize controllable injection and production in the bottom injection and production area, control the pump valves according to the set strategy, track the pressure / flow setting in a closed loop, and realize the release-back pressure procedure.

6. The experimental device for fiber optic monitoring and early warning of ground subsidence in an ultra-deep water environment as described in claim 5, characterized in that, The computer is equipped with a data processing module, a risk level classification module, and a coordinated production restriction and pressure reduction control module. The data processing module is used to perform noise reduction, temperature-strain coupling, and formation subsidence inversion on the received digital signal to obtain the formation subsidence rate. The risk level classification module is used to assess and classify the current stratum subsidence rate according to a preset risk level classification strategy. The coordinated production restriction and pressure reduction control module is used to generate corresponding coordinated production restriction and pressure reduction control commands based on risk assessment and classification results.

7. The experimental device for fiber optic monitoring and early warning of ground subsidence in an ultra-deep water environment as described in claim 6, characterized in that, The risk level classification module uses time and cumulative settlement depth as indicators, combined with the average daily settlement rate, to classify risk levels into three alarm levels: yellow, orange, and red. A yellow alert indicates that the settlement exceeds the forecast but is still controllable, corresponding to an average daily settlement rate greater than 2 mm / day, or a cumulative settlement exceeding "2t+5mm", where t is time in days; An orange alert indicates that the settlement rate and cumulative amount deviate significantly from the normal settlement range, corresponding to a daily average settlement rate greater than 5 mm / day, or a cumulative settlement exceeding "5t+10 mm"; A red alert indicates that ground subsidence has entered a danger zone, posing structural or functional risks, and requires immediate emergency response. This corresponds to a daily average subsidence rate greater than 10 mm / day, or a cumulative subsidence exceeding "10t+15mm".

8. The experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environment as described in claim 7, characterized in that, The coordinated production restriction and pressure reduction control module generates corresponding coordinated production restriction and pressure reduction control commands based on risk assessment and classification results, including: When a yellow alarm is detected, a daily production limit is set for the injection-production controller, and the collection rate of the bottom injection-production zone is reduced according to the preset step size. At the same time, formation pressure maintenance measures are assessed / prepared. When an orange alarm is detected, production is limited or stopped for the injection-production controller, and the preset pressure drop slope limit and daily production slope limit are enforced. At the same time, formation pressure maintenance measures are initiated in the bottom injection-production area to control formation-scale pressure drop. When the computer determines that a red alarm has been triggered, the injection and production controller will be shut down. If the preset conditions are met, a short-term backpressure / water injection will be performed to slow down the settling rate.

9. The experimental device for fiber optic monitoring and early warning of ground subsidence in an ultra-deep water environment as described in claim 6, characterized in that, The experimental setup also includes a timer and a camera. The timer is used to record the loading time under the working conditions, and the camera is used to observe the ground subsidence status.

10. A method for using the experimental device for fiber optic monitoring and early warning of ground subsidence in ultra-deep water environments as described in any one of claims 1 to 9, characterized in that, include: The simulation environment and operating conditions were determined according to the experimental requirements, and the formation and oil and gas extraction environment simulation system was filled with layered media. After the formation in the formation and oil and gas extraction environment simulation system is stabilized, the fiber optic monitoring system will be deployed. Connect the formation and oil and gas extraction environment simulation system, the fiber optic monitoring system, and the data processing and linkage control system, and check them to ensure that the experimental device can be used normally. The data processing and linkage control system controls the bottom layer and oil and gas extraction environment simulation system, enabling it to simulate the oil / gas extraction conditions in the required ultra-deep water environment, and continuously collects strain and temperature data streams through the fiber optic monitoring system. Based on the collected data, the formation subsidence rate is calculated to provide different risk warnings, and corresponding linkage production restriction and pressure reduction measures are taken. The actions and curves in the process are automatically recorded, parameterized reports are generated and data is backed up, and the entire process is analyzed and summarized after the experimental cycle ends. By changing the simulated environment and operating conditions, and repeating all the above steps, the impact of oil and gas extraction on formation subsidence under different environments and operating conditions was analyzed.

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