Hydraulic fracturing wellbore leak detection system and method

Abstract

The application discloses a hydraulic fracturing wellbore leakage detection system and a method thereof, and the method comprises the following steps: controlling an electro-hydraulic servo pressure regulating valve to inject hydraulic medium into a confining pressure cavity to simulate the pressure applied to the confining pressure cavity in a wellbore environment; controlling a high-pressure pump to inject high-pressure fluid into the wellbore environment to simulate a hydraulic fracturing working condition; obtaining pressure data in the confining pressure cavity and strain data of any measuring point in a cement sheath during simulation of an actual working condition; when it is monitored that the strain data exceeds a preset threshold value, triggering pressure interlock control; controlling the electro-hydraulic servo pressure regulating valve to perform graded pressure reduction on the pressure in the confining pressure cavity; and according to the monitored cement sheath temperature data and the pressure data after the pressure interlock control, adopting a least square method to fit a crack propagation path of the cement sheath. The application can improve the simulation accuracy of the dynamic crack propagation path of the cement sheath, realize qualitative speculation to quantitative reduction of the crack propagation path, and provide a reliable basis for wellbore sealing design.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and natural gas mining engineering, and in particular to a hydraulic fracturing wellbore leakage detection system and method thereof. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. No statement herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] In the oil and gas extraction sector, the integrity of the wellbore cement sheath during hydraulic fracturing operations directly impacts project safety and environmental risks. As a critical barrier layer in the wellbore, the cement sheath is susceptible to cracks under high-temperature and high-pressure conditions, which can trigger fluid channeling, leading to wellbore instability, formation fluid leakage, and even blowouts.

[0004] To address these issues, existing technologies primarily employ three approaches: geomechanical simulation methods: These methods use drilling data to establish a three-dimensional fracture model to evaluate fracture effectiveness, but rely on theoretical deduction rather than physical experiments; fiber optic monitoring technology: Distributed acoustic sensing (DAS) is used to monitor fracturing microseismic events, combining temperature and strain measurements to achieve multi-parameter acquisition; and fracturing process optimization: CN111827954A discloses a continuous pulse hydraulic fracturing system and method, proposing a continuous pulse hydraulic fracturing system; and CN115680630A proposes a leak detection method based on time-domain curve comparison.

[0005] Existing technologies have many limitations. First, the experimental environment is distorted: most devices are unable to reproduce the multi-field coupling environment downhole (such as formation pressure, temperature gradient, and fluid synergy), resulting in a large deviation between the experimental results and the actual working conditions. Second, the monitoring accuracy of existing technologies is insufficient: traditional resistance strain gauges are susceptible to electromagnetic interference and only support single-point measurement, while fiber optic sensing has the risk of signal drift under complex geological conditions and has low monitoring coverage. In addition, existing technologies lack synergy: existing research currently focuses on a single factor and lacks the coordinated monitoring of multiple parameters. It is impossible to accurately simulate the dynamic expansion path of cement sheath cracks and provide a reliable basis for wellbore sealing design. Summary of the Invention

[0006] The embodiment of the present invention provides a hydraulic fracturing wellbore leakage detection system for improving the simulation accuracy of the dynamic expansion path of cement sheath cracks and providing a reliable basis for wellbore sealing design. The system includes: a wellbore simulation subsystem, a fluid circulation subsystem, a confining pressure control module, an optical fiber detection module, and a wellbore leakage assessment module; wherein,

[0007] The wellbore simulation subsystem includes a confining pressure chamber, casing, cement sheath, insulation sleeve, and test bench. A cement sheath is installed around the casing, and the confining pressure chamber uses a metal hard seal structure to wrap the cement sheath and casing. The confining pressure chamber is used to simulate the radial pressure of the formation through hydraulic medium.

[0008] The fluid circulation subsystem includes a liquid storage tank, a high-pressure pump, a pressure-regulating valve and a return pipe. The high-pressure pump is used to pressurize the liquid in the liquid storage tank to a set pressure and then inject it into the wellbore simulation subsystem to simulate the action of high-pressure fluid. The return pipe is used to recover the reflux liquid and return the reflux liquid to the liquid storage tank to form a closed-loop circulation; the pressure-regulating valve is used to monitor the pressure; in addition, before the fluid circulation subsystem is operated, it is necessary to inject clean water into the liquid storage tank and start the pressure-stabilizing pump to perform a pipeline sealing test; then adjust the high-pressure pump to the target pressure condition, and use the electronic flowmeter to monitor the flow fluctuation characteristics in real time to verify the system's operating stability and flow control accuracy under the set pressure, completing the full-process functional verification.

[0009] The confining pressure control module includes a high-pressure pump, an electro-hydraulic servo pressure regulating valve and a pressure sensor. The high-pressure pump is used to regulate the pressure in the confining pressure chamber, the electro-hydraulic servo pressure regulating valve is used to inject hydraulic medium into the confining pressure chamber, and the pressure sensor is used to monitor the pressure value in the confining pressure chamber.

[0010] The fiber optic detection module includes an optical fiber and an optical fiber sensor inside the cement sheath. The optical fiber detection module is arranged inside the cement sheath. The optical fiber is axially spirally and circumferentially wound along the outer wall of the casing to form a three-dimensional distributed optical fiber network. The three-dimensional distributed optical fiber network is used to monitor the strain value of any measuring point in the cement sheath under stress through the optical fiber sensor. The three-dimensional distributed optical fiber network is also used to monitor the temperature value in the cement sheath through the temperature sensor.

[0011] The wellbore leakage assessment module is used to fit the crack propagation path of the cement sheath using the least squares method based on the pressure value in the confining pressure cavity, the strain value and temperature value of the cement sheath measuring point.

[0012] An embodiment of the present invention further provides a hydraulic fracturing wellbore leakage detection method for improving the simulation accuracy of the dynamic expansion path of cement sheath cracks and providing a reliable basis for wellbore sealing design. The method includes:

[0013] By controlling the electro-hydraulic servo pressure regulating valve to inject hydraulic medium into the confining pressure cavity, the pressure applied to the confining pressure cavity in the wellbore environment is simulated; by controlling the high-pressure pump to inject high-pressure fluid into the wellbore environment, the hydraulic fracturing working condition is simulated;

[0014] In the process of simulating actual working conditions, the pressure data in the confining pressure cavity and the strain data of any measuring point in the cement sheath are obtained. When the strain data exceeds the preset threshold, the pressure interlock control is triggered: the electro-hydraulic servo pressure regulating valve is controlled to perform a staged pressure reduction process on the pressure in the confining pressure cavity.

[0015] The least squares method was used to fit the crack propagation path of the cement sheath based on the monitored cement sheath temperature data and the pressure data after pressure interlock control.

[0016] An embodiment of the present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned hydraulic fracturing wellbore leakage detection method when executing the computer program.

[0017] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the above-mentioned hydraulic fracturing wellbore leakage detection method is implemented.

[0018] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned hydraulic fracture wellbore leakage detection method.

[0019] In an embodiment of the present invention, an electro-hydraulic servo pressure regulating valve is controlled to inject hydraulic medium into a confined pressure chamber to simulate the pressure applied to the confined pressure chamber in a wellbore environment; a high-pressure pump is controlled to inject high-pressure fluid into the wellbore environment to simulate hydraulic fracturing conditions; during the simulation of actual working conditions, pressure data within the confined pressure chamber and strain data at any measuring point in the cement sheath are obtained. When the strain data exceeds a preset threshold, a pressure interlock control is triggered: the electro-hydraulic servo pressure regulating valve is controlled to perform a step-by-step pressure reduction process on the pressure within the confined pressure chamber; and the least squares method is used to fit the fracture propagation path of the cement sheath based on the monitored cement sheath temperature data and the pressure data after the pressure interlock control. In the above process, the embodiment of the present invention, based on the coordinated control of the electro-hydraulic servo pressure regulating valve and the high-pressure pump, simulates the multi-field coupling environment downhole, reduces the distortion of the experimental environment, triggers the pressure interlock control by strain data, improves the response speed of the pressure reduction process, avoids the runaway of the fracture, and uses the least squares method to fit the fracture propagation path, thereby improving the simulation accuracy of the dynamic propagation path of the cement sheath crack, realizing the transition from qualitative inference to quantitative restoration of the fracture propagation path, and providing a reliable basis for wellbore sealing design. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 This is a structural diagram of a hydraulic fracturing wellbore leakage detection system according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of optical fiber layout in an embodiment of the present invention;

[0023] Figure 3 Flowchart of a hydraulic fracturing wellbore leakage detection method according to an embodiment of the present invention;

[0024] Figure 4 This is a flow chart of pressure interlock control in an embodiment of the present invention;

[0025] Figure 5 Schematic diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0027] Figure 1 The structure diagram of the hydraulic fracturing wellbore leakage detection system in an embodiment of the present invention includes: a wellbore simulation subsystem, a fluid circulation subsystem, a confining pressure control module, an optical fiber detection module and a wellbore leakage assessment module; wherein,

[0028] The wellbore simulation subsystem includes a confining pressure chamber, casing, cement sheath, insulation sleeve, and test bench. A cement sheath is installed around the casing, and the confining pressure chamber uses a metal hard seal structure to wrap the cement sheath and casing. The confining pressure chamber is used to simulate the radial pressure of the formation through hydraulic medium.

[0029] The fluid circulation subsystem includes a liquid storage tank, a high-pressure pump, a pressure regulating valve, and a return pipe. The high-pressure pump is used to pressurize the liquid in the liquid storage tank to a set pressure and then inject it into the wellbore simulation subsystem to simulate the high-pressure fluid effect. The return pipe is used to recover the return liquid and return it to the liquid storage tank to form a closed-loop circulation. The pressure regulating valve is used to monitor the pressure.

[0030] The confining pressure control module includes a high-pressure pump, an electro-hydraulic servo pressure regulating valve and a pressure sensor. The high-pressure pump is used to regulate the pressure in the confining pressure chamber, the electro-hydraulic servo pressure regulating valve is used to inject hydraulic medium into the confining pressure chamber, and the pressure sensor is used to monitor the pressure value in the confining pressure chamber.

[0031] The fiber optic detection module includes an optical fiber and an optical fiber sensor inside the cement sheath. The optical fiber detection module is arranged inside the cement sheath. The optical fiber is axially spirally and circumferentially wound along the outer wall of the casing to form a three-dimensional distributed optical fiber network. The three-dimensional distributed optical fiber network is used to monitor the strain value of any measuring point in the cement sheath under stress through the optical fiber sensor. The three-dimensional distributed optical fiber network is also used to monitor the temperature value in the cement sheath through the temperature sensor.

[0032] The wellbore leakage assessment module is used to fit the crack propagation path of the cement sheath using the least squares method based on the pressure value in the confining pressure cavity, the strain value and temperature value of the cement sheath measuring point.

[0033] like Figure 1 As shown, in a specific embodiment, the hydraulic fracturing wellbore leakage detection system includes:

[0034] Wellbore simulation subsystem: includes confining pressure chamber 7, cement sheath 8, casing 9, insulation sleeve 6, and experimental bench 10. The casing is full-scale and consistent with actual engineering conditions. The outer layer of the casing is a cement sheath to simulate the cement sheath and rock mass around the casing under actual engineering conditions. The outermost layer is an insulation layer to provide a sealed space for the experiment.

[0035] The fluid circulation subsystem includes piping connected to the wellbore simulation system and includes a fluid reservoir 1, a pressure-stabilizing pump 2, a high-pressure pump 3, a pressure sensor 4, a pressure-regulating valve 12, and a return line. During the test, the fluid circulation system initially pressurizes the fluid stored in the reservoir using the pressure-stabilizing pump. The high-pressure pump then raises the pressure to the set point. After monitoring by the pressure sensor, the fluid is injected into the perforation module of the wellbore simulation system to simulate the action of high-pressure fluid. After leaking through the wellbore and fractures, the fluid is recovered through the return line and ultimately flows back to the fluid reservoir, forming a closed-loop circulation system. The pressure-regulating valve precisely regulates the pressure of the injected fluid. The entire fluid circulation system is connected to a computer via a data acquisition and control system, enabling dynamic monitoring and automated control of fluid pressure, flow, and circulation.

[0036] Confining pressure control module: The high-pressure simulation unit 18 opens the safety valve 15, allowing the high-pressure pump 3 to inject high-pressure liquid, thereby applying confining pressure to the confining pressure cavity, and accurately controls the pressure in the confining pressure cavity through the electro-hydraulic servo pressure regulating valve 19. The confining pressure cavity completely wraps the cement ring 8 and the casing 9, simulating the squeezing environment of the formation on the wellbore. The pressure sensor in the confining pressure cavity is used to monitor the actual confining pressure and transmit the pressure data to the computer 11 to achieve real-time monitoring and recording of the pressure. The manual pressure relief valve ensures the safe release of the pressure in the confining pressure cavity after the experiment. Among them, in the process of injecting confining pressure into the confining pressure cavity, a graded pressure loading mode is adopted. In the initial stage, the pressure is increased to the target fracture pressure at a preset rate and then switched to pressure stabilization control. The dynamic equilibrium state of injection and backflow is tracked in real time through the flow monitoring system.

[0037] Cement sheath evaluation subsystem includes the following modules:

[0038] The strain detection module, located on the outer wall of the cement sheath sealing model, consists of a strain detector 21, a data acquisition system 25, and a computer 11. One end of the strain detector is connected to the cement sheath to sense strain changes caused by stress, and the other end is connected to the computer via a data transmission line. During the experiment, changes in wellbore pressure cause strain in the cement sheath. The strain detector converts the signal into an electrical signal and transmits it to the data acquisition system, which then displays the strain data in real time on the computer. Through the human-computer interface, users can observe the strain and stress distribution of the cement sheath, analyze the cement sheath sealing performance, and provide reliable data support for optimizing wellbore design and isolation technology.

[0039] The fiber optic detection module, located within the cement sheath, monitors crack formation and propagation in real time, capturing strain changes and crack path data under stress. The module includes an internal fiber optic cable 26, a pressure detector 20, a fiber optic detector 23, and a fiber optic demodulator 24, each with complementary functions. A fully integrated fiber optic layout utilizes a three-dimensional monitoring network. During the cement sheath pouring phase, a multi-layer fiber optic array (cross-layout, axial and circumferential) is pre-embedded, covering the entire cement sheath-stratum interface. Traditional methods involve only externally attaching a single layer of fiber. Flexible ceramic-coated fiber is used for the packaging, offering high temperature and pressure resistance to prevent fiber breakage or signal drift in high-pressure environments.

[0040] Before wrapping the optical fiber around the casing, the casing undergoes pretreatment: the surface is sandblasted to increase its roughness. A spiral groove (50mm pitch, 1mm depth) is then engraved on the outer wall of the casing to secure the optical fiber. During fiber routing, an axial monitoring layer is installed, continuously wound along the spiral groove in a single layer (50mm pitch) with an axial coverage density of 20 turns / meter. The ends of each layer are connected to the fiber optic terminal box at the wellhead. During the circumferential layout of the optical fiber, FBG temperature measurement chains are installed every 200mm from the casing end, with each chain spaced 10nm apart. Two FBG temperature measurement chains are placed at each end of the casing, spaced 180° apart, to compensate for axial temperature gradients. Encapsulation and protection are also essential: the optical fiber surface is coated with high-temperature-resistant silicone to prevent cement corrosion. Axial temperature gradient data is collected using the FBG temperature measurement chains. The temperature gradient data is then fused with strain data using a Kalman filter to eliminate strain measurement errors caused by thermal expansion.

[0041] The axial fiber layout helically winds along the outer wall of the casing, ensuring that each fiber loop covers a different radial depth of the cement sheath. The core function of the axial fiber: The helically wound structure (50mm pitch) forms a continuous monitoring band, directly capturing the trajectory of the fracture along the wellbore axis (Z direction). The continuous distribution of fiber strain jumps provides a visual indication of the longitudinal fracture extension length. In conjunction with the circumferential temperature measurement chain, it directly measures the longitudinal temperature gradient in the wellbore, offsetting strain measurement deviations caused by thermal expansion through physical layout. Four FBG temperature measurement chains (each containing 10 gratings, with an axial spacing of 200mm) are deployed 90° apart at the cement sheath-formation interface in the circumferential direction to monitor the temperature gradient. The core function of the circumferential fiber: Four fiber groups (0°, 90°, 180°, and 270°) are arranged at 90° intervals to form an azimuth monitoring network. Continuous strain jumps in a given fiber position directly determine the dominant fracture extension direction. The intersections of the axial and circumferential fibers form a spatial coordinate grid.

[0042] The fiber optic detector was used during the experimental preparation phase to verify the strength and transmission stability of the fiber optic signal, ensuring optimal performance of the fiber optic sensor. During the experiment, the fiber optic demodulator analyzed the fiber optic signal in real time, converting the crack propagation path and dynamic strain distribution into visual data. This data was then transmitted to a computer 11 for analysis via a data acquisition system 25. The design of the fiber optic module significantly improved the reliability and accuracy of the experimental data, providing key technical support for the dynamic evaluation of cement sheath sealing performance.

[0043] The temperature detection module, consisting of temperature detectors 22 placed within the cement sheath and at key locations within the experimental setup, monitors temperature changes within the cement sheath and the experimental environment in real time. The temperature sensors record the temperature distribution inside and outside the cement sheath, as well as temperature fluctuations in the experimental environment, to evaluate the mechanical properties and crack propagation characteristics of the cement sheath under different temperature conditions. Furthermore, the temperature measurement data can be used to calibrate the fiber optic and strain sensors, ensuring the accuracy of experimental measurements. Temperature data is combined with other sensor data and fused with temperature-strain data using a Kalman filter algorithm to eliminate interference from thermal expansion effects on crack monitoring, providing important support for comprehensive analysis of experimental results and reliability verification.

[0044] The wellbore leakage assessment module 5 is used to fit the crack propagation path of the cement sheath using the least square method according to the pressure value in the confining pressure cavity, the strain value and the temperature value of the cement sheath measuring point.

[0045] In one embodiment, the fiber optic sensor and the electro-hydraulic servo pressure regulating valve are directly connected via hardwiring. This direct hardwiring connection achieves millisecond-level response to crack propagation and pressure regulation. Compared to traditional manual intervention, this reduces incident response time from minutes to seconds and avoids the risk of crack data corruption caused by software system crashes.

[0046] In one embodiment, it further includes:

[0047] The controller is used to receive the strain value monitored by the optical fiber sensor; the controller is also used to control the electro-hydraulic servo pressure regulating valve to perform graded pressure reduction processing on the pressure in the confining pressure cavity when the strain value of any measuring point of the cement sheath in the monitoring result exceeds a preset threshold.

[0048] In a specific embodiment, when the optical fiber sensor detects that the strain value of any measuring point in the cement sheath exceeds the first preset threshold, a first-level interlock response is triggered, and the electro-hydraulic servo pressure regulating valve is controlled to linearly reduce the output pressure of the high-pressure pump at a rate of 1-2 MPa / s; when it is detected that three or more adjacent measuring points reach the second preset threshold at the same time, a second-level interlock response is triggered, and the electro-hydraulic servo pressure regulating valve is controlled to reduce the pressure to a safe threshold within 5 seconds.

[0049] In one embodiment, the outer layer of the optical fiber is wrapped with a silicone flexible sheath; and a flexible ceramic coating is wrapped at the intersection between the axially helically wound optical fiber and the circumferentially wound optical fiber.

[0050] Figure 2 FIG. 1 is a schematic diagram of optical fiber layout according to an embodiment of the present invention. Figure 2 As shown, green represents zero-degree fiber, and blue represents 90-degree fiber. A double-layer flexible ceramic coating is applied at the intersection 27. The axial fiber uses the 1550nm band, while the circumferential fiber uses the 1310nm band, achieving spectral separation and preventing interference. Furthermore, shear resistance is required. The fiber passes through a pre-installed silicone flexible sleeve (elastic modulus ≤ 1 MPa). A porous ceramic coating is applied to the fiber to ensure it can expand and contract freely as the cement solidifies and contracts. This prevents fiber breakage caused by cement solidification and shrinkage.

[0051] In one embodiment, the fluid circulation subsystem further comprises:

[0052] Filtration device for multi-stage particle removal and purification of reflux liquid;

[0053] Electronic flow meter, used to monitor the flow difference between the injected liquid and the return liquid as leakage.

[0054] like Figure 1 As shown, the fluid circulation subsystem also includes an electronic flowmeter 13 and a filter device 14. After leaking through the wellbore and fractures, the liquid is recovered through a return line. Opening valve 17, it enters the filter device for particulate removal and purification. Finally, opening valve 16, it flows back to the storage tank, forming a closed-loop circulation system. Simultaneously, a pressure-regulating valve precisely adjusts the pressure of the injected liquid, and an electronic flowmeter monitors the flow rates of the injected and recovered liquid in real time, thereby calculating the amount of liquid leakage and the system's pressure drop, ensuring the accuracy of experimental data.

[0055] In a specific embodiment, the leakage rate inverted by the optical fiber is compared with the leakage rate measured by the electronic flowmeter. When the error exceeds a preset error threshold, temperature compensation is initiated. A neural network model is trained based on pressure, temperature, and strain data to establish a mapping relationship between the crack propagation path and the leakage rate. A quantitative assessment report of the crack azimuth, extension length, and aperture distribution is output. This invention significantly improves the data reliability of downhole crack monitoring through dynamic leakage verification and temperature compensation mechanisms. Based on the neural network model, it accurately predicts the crack propagation path and leakage rate, ultimately generating a full-dimensional quantitative crack assessment report, providing high-precision data support for wellbore integrity decision-making.

[0056] The present invention also provides a method for detecting hydraulic fracture wellbore leakage, as described in the following embodiments. Because the principles of this device are similar to those of a hydraulic fracture wellbore leakage detection system, the implementation of this device can be referenced to the implementation of a hydraulic fracture wellbore leakage detection system, and any repetitions will not be repeated.

[0057] Figure 3 Flowchart of a hydraulic fracturing wellbore leakage detection method according to an embodiment of the present invention, the method comprising:

[0058] Step 301: injecting a hydraulic medium into the confining pressure cavity by controlling an electro-hydraulic servo pressure regulating valve to simulate the pressure applied to the confining pressure cavity in a wellbore environment; and injecting a high-pressure fluid into the wellbore environment by controlling a high-pressure pump to simulate a hydraulic fracturing condition.

[0059] Step 302: During the simulation of actual working conditions, pressure data within the confining pressure cavity and strain data at any measuring point in the cement sheath are acquired. When the strain data exceeds a preset threshold, a pressure interlock control is triggered: the electro-hydraulic servo pressure regulating valve is controlled to perform a stepwise pressure reduction process on the pressure within the confining pressure cavity.

[0060] Step 303 : fitting the crack propagation path of the cement sheath using the least square method based on the monitored cement sheath temperature data and the pressure data after pressure interlock control.

[0061] In a specific embodiment, the pressure data in the confining pressure cavity, the strain data and temperature data of the cement sheath measuring point are used to reproduce the downhole multi-field coupling environment (formation pressure, temperature gradient, and fluid synergy), thereby reducing the deviation between the experimental results and the actual working conditions.

[0062] Figure 4 This is a flow chart of the pressure interlock control in an embodiment of the present invention. In one embodiment, triggering the pressure interlock control: controlling the electro-hydraulic servo pressure regulating valve to perform a staged pressure reduction process on the pressure in the confining pressure chamber includes:

[0063] Step 401: When the strain data of any measuring point in the cement sheath exceeds a first preset threshold, a first-level interlock response is triggered: the electro-hydraulic servo pressure regulating valve is controlled to linearly reduce pressure at a preset rate;

[0064] Step 402 : When the strain data of three or more adjacent measuring points in the cement sheath simultaneously exceed the second preset threshold, a secondary interlock response is triggered: the electro-hydraulic servo pressure regulating valve is controlled to reduce the pressure to within a safe pressure threshold range within a preset time period.

[0065] An embodiment of the present invention further provides a computer device, Figure 5 This is a schematic diagram of a computer device in an embodiment of the present invention. The computer device 500 includes a memory 510, a processor 520, and a computer program 530 stored in the memory 510 and executable on the processor 520. When the processor 520 executes the computer program 530, the above-mentioned hydraulic fracturing wellbore leakage detection method is implemented.

[0066] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the above-mentioned hydraulic fracturing wellbore leakage detection method is implemented.

[0067] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned hydraulic fracture wellbore leakage detection method.

[0068] In an embodiment of the present invention, an electro-hydraulic servo pressure regulating valve is controlled to inject hydraulic medium into a confined pressure chamber to simulate the pressure applied to the confined pressure chamber in a wellbore environment; a high-pressure pump is controlled to inject high-pressure fluid into the wellbore environment to simulate hydraulic fracturing conditions; during the simulation of actual working conditions, pressure data within the confined pressure chamber and strain data at any measuring point in the cement sheath are obtained. When the strain data exceeds a preset threshold, a pressure interlock control is triggered: the electro-hydraulic servo pressure regulating valve is controlled to perform a step-by-step pressure reduction process on the pressure within the confined pressure chamber; and the least squares method is used to fit the fracture propagation path of the cement sheath based on the monitored cement sheath temperature data and the pressure data after the pressure interlock control. In the above process, the embodiment of the present invention, based on the coordinated control of the electro-hydraulic servo pressure regulating valve and the high-pressure pump, simulates the multi-field coupling environment downhole, reduces the distortion of the experimental environment, triggers the pressure interlock control by strain data, improves the response speed of the pressure reduction process, avoids the runaway of the fracture, and uses the least squares method to fit the fracture propagation path, thereby improving the simulation accuracy of the dynamic propagation path of the cement sheath crack, realizing the transition from qualitative inference to quantitative restoration of the fracture propagation path, and providing a reliable basis for wellbore sealing design.

[0069] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0070] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0071] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0072] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0073] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hydraulic fracturing wellbore leakage detection system, characterized in that: include: Wellbore simulation subsystem, fluid circulation subsystem, confining pressure control module, fiber optic detection module and wellbore leakage assessment module; among them, The wellbore simulation subsystem includes a confining pressure chamber, casing, cement sheath, insulation sleeve, and test bench. A cement sheath is installed around the casing, and the confining pressure chamber uses a metal hard seal structure to wrap the cement sheath and casing. The confining pressure chamber is used to simulate the radial pressure of the formation through hydraulic medium. The fluid circulation subsystem includes a liquid storage tank, a high-pressure pump, a pressure regulating valve, and a return pipe. The high-pressure pump is used to pressurize the liquid in the liquid storage tank to a set pressure and then inject it into the wellbore simulation subsystem to simulate the high-pressure fluid effect. The return pipe is used to recover the return liquid and return it to the liquid storage tank to form a closed-loop circulation. The pressure regulating valve is used to monitor the pressure. The confining pressure control module includes a high-pressure pump, an electro-hydraulic servo pressure regulating valve and a pressure sensor. The high-pressure pump is used to regulate the pressure in the confining pressure chamber, the electro-hydraulic servo pressure regulating valve is used to inject hydraulic medium into the confining pressure chamber, and the pressure sensor is used to monitor the pressure value in the confining pressure chamber. The fiber optic detection module includes an optical fiber and an optical fiber sensor inside the cement sheath. The optical fiber detection module is arranged inside the cement sheath. The optical fiber is axially spirally and circumferentially wound along the outer wall of the casing to form a three-dimensional distributed optical fiber network. The three-dimensional distributed optical fiber network is used to monitor the strain value of any measuring point in the cement sheath under stress through the optical fiber sensor. The three-dimensional distributed optical fiber network is also used to monitor the temperature value in the cement sheath through the temperature sensor. The wellbore leakage assessment module is used to fit the crack propagation path of the cement sheath using the least squares method based on the pressure value in the confining pressure cavity, the strain value and temperature value of the cement sheath measuring point.

2. The system according to claim 1, wherein The optical fiber sensor is directly connected to the electro-hydraulic servo pressure regulating valve through hard wiring.

3. The system according to claim 1, wherein: Also includes: The controller is used to receive the strain value monitored by the optical fiber sensor; the controller is also used to control the electro-hydraulic servo pressure regulating valve to perform graded pressure reduction processing on the pressure in the confining pressure cavity when the strain value of any measuring point of the cement sheath in the monitoring result exceeds a preset threshold.

4. The system according to claim 1, wherein: The outer layer of the optical fiber is wrapped with a silicone flexible sleeve; and a flexible ceramic coating is wrapped at the intersection between the axially spirally wound optical fiber and the circumferentially wound optical fiber.

5. The system according to claim 1, wherein: The fluid circulation subsystem also includes: Filtration device for multi-stage particle removal and purification of reflux liquid; Electronic flow meter, used to monitor the flow difference between the injected liquid and the return liquid as leakage.

6. A method for detecting leakage in a hydraulic fracturing wellbore, characterized in that: The method is applied to the hydraulic fracturing wellbore leakage detection system according to any one of claims 1 to 5, and the method comprises: By controlling the electro-hydraulic servo pressure regulating valve to inject hydraulic medium into the confining pressure cavity, the pressure applied to the confining pressure cavity in the wellbore environment is simulated; by controlling the high-pressure pump to inject high-pressure fluid into the wellbore environment, the hydraulic fracturing working condition is simulated; In the process of simulating actual working conditions, the pressure data in the confining pressure cavity and the strain data of any measuring point in the cement sheath are obtained. When the strain data exceeds the preset threshold, the pressure interlock control is triggered: the electro-hydraulic servo pressure regulating valve is controlled to perform a staged pressure reduction process on the pressure in the confining pressure cavity. The least squares method was used to fit the crack propagation path of the cement sheath based on the monitored cement sheath temperature data and the pressure data after pressure interlock control.

7. The method according to claim 6, wherein Triggering pressure interlock control: Controlling the electro-hydraulic servo pressure regulating valve to perform graded pressure reduction on the pressure in the confining pressure chamber, including: When the strain data of any measuring point in the cement sheath exceeds the first preset threshold, a first-level interlock response is triggered: the electro-hydraulic servo pressure regulating valve is controlled to linearly reduce the pressure at a preset rate; When the strain data of three or more adjacent measuring points in the cement sheath simultaneously exceeds the second preset threshold, a secondary interlock response is triggered: the electro-hydraulic servo pressure regulating valve is controlled to reduce the pressure to a safe pressure threshold range within a preset time.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 6 to 7 is implemented.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 6 to 7 is implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 6 to 7 is implemented.

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