Underground distributed optical fiber air bag coupling recovery method and system and application of underground distributed optical fiber air bag coupling recovery method and system

Abstract

The invention discloses an underground distributed optical fiber air bag coupling recovery system which comprises an air bag and an inflation control system connected with the air bag. The inflation control system comprises an electromagnetic valve, a high-pressure nitrogen cylinder and a pressurizing inflation pump, the output end of the high-pressure nitrogen cylinder is connected with one end of a main air pipe, the surface of the main air pipe is provided with a plurality of mounting holes and connected with one ends of a plurality of inflation pipes, and the other ends of the inflation pipes are used for being connected with air inlets and air outlets of the air bags; an electromagnetic valve is mounted on each gas filling pipe; the other end of the main air pipe is connected with the input end of the vacuum pump through another corresponding electromagnetic valve. Coupling of the optical cable and the well wall is achieved through inflation and deflation of the air bag, and higher efficiency is achieved; the method adapts to the environment, can resist the high pressure of 10 MPa and the temperature of-30 DEG C to 120 DEG C, and is suitable for the complex underground environment; the device is convenient to operate and supports independent control of a single air bag, and the recovery efficiency is improved by 80% or above.

Description

Technical Field

[0001] The present application belongs to the field of earthquake detection and relates to a downhole distributed optical fiber airbag coupling recovery technology, specifically a downhole distributed optical fiber airbag coupling recovery method, system and application thereof. Background Art

[0002] In fields such as oil and gas field monitoring and geological exploration, downhole fiber optic sensing technology requires stable fixing of optical fibers to the wellbore wall for signal coupling. Traditionally, sand-filled coupling is used, but this easily loses its properties in wet environments, resulting in unstable coupling and making cable recovery difficult.

[0003] In existing technologies, some devices use mechanical stabilizers or fixed brackets, but they cannot adapt to irregular well walls. Although airbag technology is used in ground fiber optic connections (such as CN217521400U), it lacks distributed control and recyclable design for high-pressure and wet environments underground, and cannot meet the needs of complex working conditions. Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art; to this end, the present application proposes a downhole distributed optical fiber airbag coupling recovery method, device and application thereof, which are used to solve the technical problem that downhole optical fiber is difficult to recover. The present application solves the above-mentioned problem through the technology of optical cable combined with airbag expansion coupling and airbag contraction recovery.

[0005] To achieve the above objectives, the first aspect of the present application provides a downhole distributed optical fiber airbag coupling recovery method, the method being applied to a coupling recovery system, the coupling recovery system comprising a distributed optical fiber, the distributed optical fiber being an optical cable for vibration detection, the optical cable being sequentially connected in series to a plurality of test wells, and the optical cable forming a U-shape in the test well; a plurality of airbags for coupling with the inner wall of the test well being provided at intervals on the optical cable in the test well; a main air pipe being arranged along the optical cable in the test well, the airbags being connected to the main air pipe via an inflation pipe, the main air pipe extending outside the test well and connected to an inflation and deflation unit, the optical cables being respectively connected to a detection unit, the detection unit comprising an optical signal transmitter and a detector; The downhole distributed optical fiber airbag coupling recovery method includes the following steps: Step 1: Assemble the equipment. Select an appropriate length of optical cable according to the depth of the test well. Fold the middle of the optical cable in half so that a portion of the cable forms a U-shaped double-strand state, i.e., a double-strand structure, for lowering into the test well. Airbag installation: Based on the depth of the test well, multiple airbags are then fixed to the surface of the double-strand optical cable through a carbon fiber "C"-shaped bracket; Step 2: Insert the device. Lowering stage: The assembled airbag, inflation tube, and optical cable are lowered into the test well. The RFID tag is read by an RFID reader to locate the airbag in real time. The two ends of the optical cable are then connected to the output of the optical signal transmitter and the input of the detector respectively. Step 3: Inflation coupling. When each airbag reaches the specified depth, the valve of the high-pressure nitrogen cylinder is manually opened and the airbag is inflated through the pipeline, allowing the airbag to expand in the well, thereby coupling the optical cable with the well wall. The valve of the high-pressure nitrogen cylinder is then closed, allowing the vibration to be transmitted through the well wall to the airbag, causing the optical cable to deform and obtain data. Step 4: Recycling After the test is completed, the airbag is quickly depressurized manually and the air is pumped out by a vacuum pump to make the airbag shrink rapidly. Then, the double-strand structure is synchronously pulled out to the bottom of the well by a double winch and a strap.

[0006] A downhole distributed fiber optic airbag coupling recovery system includes an airbag and an inflation control system connected thereto; the inflation control system includes a solenoid valve, a high-pressure nitrogen cylinder, and a pressurized inflation pump; the output end of the high-pressure nitrogen cylinder is connected to one end of a main air pipe; the surface of the main air pipe has multiple mounting holes and is connected to one end of multiple inflation tubes; the other end of the inflation tube is used to connect to the air inlet and outlet of the airbag; each of the inflation tubes is installed with a solenoid valve; the other end of the main air pipe is connected to the input end of a vacuum pump through another corresponding solenoid valve.

[0007] A downhole distributed optical fiber airbag coupling recovery method and device are used in the field of earthquake detection.

[0008] Compared with the prior art, the present invention has the following advantages: The present application realizes the coupling between the optical cable and the well wall by inflating and deflating the air bag, which is more efficient and does not have the problems of difficult recovery and easy loss of the filler when using sand filling; Environmental adaptability of this application: resistant to 10MPa high pressure, -30-120℃ temperature, suitable for complex underground environment; This application is easy to operate: it supports independent control of a single airbag and improves recovery efficiency by more than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0010] Figure 1 This is a flowchart for the application.

[0011] Figure 2 This is a control diagram of the PLC control system of this application.

[0012] Figure 3 This is a schematic diagram of the optical cable in the well in this application.

[0013] Figure 4 This is a schematic cross-sectional view of the airbag in this application.

[0014] Figure 5 This is a schematic diagram of the airbag inflation system of this application.

[0015] Figure 6 Schematic diagram of the layout of optical cables in multiple wells. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions of this application in conjunction with the embodiments. Obviously, the embodiments described are only a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application. Example 1, please refer to Figure 1-5 FIG. 1 , an embodiment of the first aspect of the present application provides a downhole distributed optical fiber airbag coupling recovery method, the steps of which are as follows: Step 1: Assemble the equipment. Select an optical cable 5 of appropriate length according to the depth of the test well. Fold the middle of the optical cable 5 in half so that a portion of the cable forms a U-shaped double-strand state, i.e., a double-strand structure, for lowering into the test well. Airbag installation: According to the depth of the test well, multiple airbags are then fixed to the surface of the double-stranded optical cable 5 through a carbon fiber "C"-shaped bracket 13, with adjacent airbags 6 spaced 0.5-2 meters apart; The air inlet of the airbag 6 is connected to the output end of the inflation tube 10 ; the input end of the inflation tube 10 is communicated with the main air pipe 2 .

[0017] Step 2: Insert the device. Lowering stage: The assembled airbag 6, inflation tube 10 and optical cable 5 are lowered into the test well at a speed of 1 m / s, and the airbag position is located in real time by reading the RFID tag with an RFID card reader; The U-shaped end of the double-stranded optical cable 5 is connected to the counterweight 7 through a carabiner 12, and the optical cable is lowered by the gravity of the counterweight 7, so that the optical cable is lowered smoothly and remains vertical; Then, both ends of the optical cable 5 are connected to the output end of the optical signal transmitter and the input end of the detector respectively.

[0018] Specifically: The method for locating the position of the airbag 6 by using an RFID card reader to read the RFID tag is as follows: The RFID tags fixed thereon are numbered in sequence according to the order of the multiple airbags 6 installed on the double-strand structure (e.g., airbag 1...airbag N); during the lowering of the airbags, an RFID reader is placed at the wellhead or a handheld RFID reader is manually held to read and record each RFID tag passing through the RFID reader position; Furthermore, when testing multiple wells, the above method can be used to number each well, such as (Bag A1, Bag A2, Bag AN), (Bag B1, Bag B2, Bag BN), etc. Because RFID tags are used for location recording, large amounts of data can be quickly recorded and stored in a computer, improving data collection and recording efficiency.

[0019] At the same time, according to the preset spacing m between the airbags 6 and the number N of airbags in each well, the lowering depth Nm can be obtained, making data acquisition more convenient.

[0020] In order to know the lowering depth in each well more accurately, the wellhead of each well can be manually controlled to be flush with the air bag 6 located at the top.

[0021] Step 3: Inflation coupling: One end of the main gas pipe 2 is connected to a high-pressure nitrogen cylinder. When each airbag 6 reaches the specified depth, the valve switch of the high-pressure nitrogen cylinder 4 is manually opened to inflate the airbag, allowing the airbag 6 to expand in the well, thereby generating coupling between the optical cable 5 and the well wall. That is, vibration can be transmitted to the airbag through the well wall, causing the optical cable to deform and obtain data; The inflation control system includes a high-pressure nitrogen cylinder, a solenoid valve and a PLC controller, which controls the switching of the corresponding solenoid valves to achieve the synchronous inflation of the airbags 6 and the targeted inflation of a single airbag 6; The ground PLC controller controls the solenoid valve 3 to open, and nitrogen is filled to 0.8 MPa within 0.5 seconds. A hole is opened on the surface of the airbag 6 and the hole is connected to the input end of the barometer (the barometer can be a wireless barometer, or the barometer can be connected to the ground through a cable to the PLC controller). The barometer feeds back a signal to the console to ensure uniform coupling pressure.

[0022] Step 4: Recycling After the test is completed, the ground system first quickly depressurizes the airbag 6 to 0.1MPa, then uses a vacuum pump to pump air to quickly shrink the airbag, and then uses the double winches on the mobile carrier and the binding belts to synchronously pull out the double-strand structure of the optical cable 5 lowered to the bottom of the well at a speed of 2m / s. Example 2, please refer to Figure 1-5FIG, another embodiment of the present application provides a downhole distributed fiber optic airbag coupling recovery system, including an optical cable 5, a main air pipe 2 and an inflation tube 10. This embodiment takes two main air pipes 2 and ten inflation tubes 10 as an example.

[0023] Specifically, the optical cable is an 8mm diameter cable with an extruded PE wear-resistant sheath, the diameter of the main air pipe is 10mm, and the diameter of the inflation tube can be 6mm. The main air pipe 2 is a Kevlar fiber reinforced PVC tube with a pressure resistance of 2MPa.

[0024] The airbag 6 is composed of an outer layer of aramid fiber-reinforced rubber and an inner layer of fluororubber coating. It is cylindrical with a through-hole formed in the middle along its axial direction. The airbag is 10 cm long in the axial direction and has an outer diameter of 12 mm when not inflated. The aramid fiber-reinforced rubber has a tensile strength of ≥15 MPa, and the inner fluororubber coating prevents deformation of the outer layer. The inner wall of the inner ring of the airbag 6 is vulcanized to connect the two ends of the "C"-shaped bracket 11 (the "C"-shaped bracket can also be made of carbon fiber material). There are multiple "C"-shaped brackets 11, and an area for fixing the optical cable is formed between the "C"-shaped bracket 11 and the inner ring wall of the airbag 6.

[0025] The inner circle wall of the airbag 6 is integrally connected with a number of evenly distributed protrusions (not shown in the figure). The protrusions are used to strengthen the positioning of the optical cable 5 to improve the coupling effect between the optical cable 5 and the well wall. The thickness of the protrusion can be 0.5 mm, and the distance between two adjacent protrusions is 2 mm.

[0026] In actual use, according to the number of test wells 1 dug (such as Figure 6 , Well A, Well B, Well C... etc.), the optical cable 5 can be bent from its middle into multiple double-strand structures, and the length of the double-strand structure can be manually adjusted according to the depth of the test well (the optical cable here can be of a length that meets the use requirements. If one optical cable is not enough, it can be manually lengthened by fusion splicing); The double-strand structure of the optical cable 5 is fixedly connected to a plurality of airbags 6 . Specifically, the double-strand structure is clamped between the “C”-shaped bracket 11 and the inner circle wall of the airbag 6 .

[0027] The outer side of the "C"-shaped bracket is sprayed with a polytetrafluoroethylene lubricating coating.

[0028] One end of the double-strand structure used for lowering to the bottom of the well can be connected to the counterweight 7 through a carabiner 12 to facilitate rapid and straight lowering.

[0029] The airbag 6 is connected to an inflation control system.

[0030] The inflation control system includes a solenoid valve 3, a high-pressure nitrogen cylinder 4 and a booster inflation pump 7. The output end of the high-pressure nitrogen cylinder 4 is connected to one end of the main air pipe 2. A plurality of mounting holes are provided on the surface of the main air pipe 2 and connected to one end of a plurality of inflation tubes 10. The other end of the inflation tube 10 is used to connect to the air inlet and outlet of the airbag 6. A solenoid valve 3 is installed on each of the inflation tubes 10 to facilitate the control of the on and off of each inflation tube 10.

[0031] The other end of the main air pipe 2 is connected to the input end of the vacuum pump 8 through another corresponding solenoid valve 3. The vacuum pump 8 cooperates with the exhaust to ensure that the air bag shrinks to the minimum, making it convenient to lift out the optical cable.

[0032] A boosting mechanism is provided between the high-pressure nitrogen cylinder 4 and the main gas pipe 2. The boosting mechanism includes a boosting pump 7 and a three-way solenoid valve 9. One input end of the three-way solenoid valve 9 and the input end of the boosting pump 7 are connected to the gas output port of the high-pressure nitrogen cylinder 4 through a three-way pipe. The other input end of the three-way solenoid valve 9 is connected to the output end of the boosting pump 7. The output end of the three-way solenoid valve 9 is connected to one end of the main gas pipe. According to the downhole pressure situation, the three-way solenoid valve 9 is selected to conduct the boosting pump 7, and then the boosting pump 7 is started to input high-pressure gas into the airbag to ensure that the pressure of each airbag meets the requirements.

[0033] The three-way solenoid valve 9 can be controlled manually or by connecting it to a PLC controller and controlling it through an input device connected to the PLC controller, wherein the input device includes a keyboard and a display. Example 3, as Figure 2 A pressure sensor is provided in the airbag 6. The installation position of the pressure sensor is located on the inner ring wall of the airbag 6. The pressure sensor is connected to the PLC controller through a signal transmission line to realize the control of the air pressure of the airbag 6. The PLC controller is also connected to the solenoid valve 3. The solenoid valve 3 is opened according to the inflation needs. At the same time, the pressure sensor transmits the airbag pressure data to the PLC controller, and the pressure data is displayed on the display unit connected to the output interface of the PLC controller.

[0034] Specifically, the solenoid valve 3 and the air pressure sensor corresponding to each airbag 6 are numbered in the PLC controller to facilitate accurate data collection and control.

[0035] The PLC controller is also connected to an RFID reader; the RFID reader is used to collect the position information of the RFID tag, and the RFID tag is fixedly connected to the end of the airbag 6 or the inner wall of the inner ring, so that the length of the double-strand structure of the optical cable 5 can be conveniently recorded by numbering the RFID tag.

[0036] The above embodiments are only used to illustrate the technical method of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present application.

Claims

1. A downhole distributed optical fiber airbag coupling recovery method, characterized in that: The method is applied to a coupling recovery system, which includes a distributed optical fiber, which is an optical cable for vibration detection. The optical cable is sequentially connected to several test wells, and the optical cable is U-shaped in the test well. A plurality of air bags for coupling with the inner wall of the test well are arranged at intervals on the optical cable in the test well. A main air pipe is arranged along the optical cable in the test well. The air bags are connected to the main air pipe through an inflation pipe. The main air pipe extends outside the test well and is connected to an inflation and deflation unit. The optical cables are respectively connected to a detection unit. The detection unit includes an optical signal transmitter and a detector. The downhole distributed optical fiber airbag coupling recovery method includes the following steps: Step 1: Assemble the equipment. Select an appropriate length of optical cable according to the depth of the test well. Fold the middle of the optical cable in half so that a portion of the cable forms a U-shaped double-strand state, i.e., a double-strand structure, for lowering into the test well. Airbag installation: Based on the depth of the test well, multiple airbags are fixed to the surface of the double-strand optical cable through carbon fiber "C"-shaped brackets; Step 2: Insert the device. Lowering phase: The assembled airbag, inflation tube, and optical cable are lowered into the test well. The airbag's position is located in real time by reading the RFID tag with an RFID reader. The two ends of the optical cable are then connected to the output of the optical signal transmitter and the input of the detector, respectively. A counterweight is attached to the U-shaped end of the double-strand optical cable via a carabiner, and the cable is lowered using the gravity of the counterweight, ensuring smooth lowering and maintaining a vertical position. Step 3: Inflation coupling. When each airbag reaches the specified depth, the valve of the high-pressure nitrogen cylinder is manually opened and the airbag is inflated through the pipeline, allowing the airbag to expand in the well, thereby coupling the optical cable with the well wall. The valve of the high-pressure nitrogen cylinder is then closed, allowing the vibration to be transmitted through the well wall to the airbag, causing the optical cable to deform and obtain data. Step 4: Recycling After the test is completed, the airbag is quickly depressurized manually and the air is pumped out by a vacuum pump to make the airbag shrink rapidly. Then, the double-strand structure is synchronously pulled out to the bottom of the well by a double winch and a strap.

2. A downhole distributed optical fiber airbag coupling recovery method according to claim 1, characterized in that: The method for locating the airbag position by using an RFID card reader to read the RFID tag is as follows: The RFID tags fixed on the airbags are numbered in sequence according to the order of the multiple airbags installed on the double-strand structure. During the lowering process of the airbags, an RFID reader is used at the wellhead to read and record the information of each RFID tag. At the same time, the lowering depth Nm can be obtained based on the preset spacing m between the airbags and the number N of airbags in each well.

3. The downhole distributed optical fiber airbag coupling recovery method according to claim 1, characterized in that: The airbag surface is provided with a hole connected to the input end of a barometer, the barometer is connected to a PLC controller on the ground for communication, and the barometer is used to feed back signals to the console to ensure uniform coupling pressure of the airbag.

4. The downhole distributed optical fiber airbag coupling recovery method according to claim 1, characterized in that: The air inlet and outlet of each airbag are connected to the pipeline through a solenoid valve, and the switch of the corresponding solenoid valve is controlled to achieve the synchronous inflation of the airbags and the inflation of a single airbag in a targeted manner.

5. The downhole distributed optical fiber airbag coupling recovery method according to claim 1, characterized in that: The interval between adjacent air bags is 0.5-2 meters.

6. A downhole distributed fiber optic airbag coupling recovery system, comprising an airbag and an inflation control system connected thereto; The inflation control system includes a solenoid valve, a high-pressure nitrogen cylinder and a booster inflation pump. The output end of the high-pressure nitrogen cylinder is connected to one end of the main air pipe. Multiple mounting holes are provided on the surface of the main air pipe and connected to one end of multiple inflation tubes. The other end of the inflation tube is used to connect to the air inlet and outlet of the airbag; each of the inflation tubes is installed with a solenoid valve; the other end of the above-mentioned main air pipe is connected to the input end of the vacuum pump through another corresponding solenoid valve.

7. The downhole distributed optical fiber airbag coupling recovery system according to claim 6, characterized in that: A boosting mechanism is provided between the high-pressure nitrogen cylinder and the main gas pipe. The boosting mechanism includes a boosting pump and a three-way solenoid valve. One input end of the three-way solenoid valve and the input end of the boosting pump are connected to the gas output port of the high-pressure nitrogen cylinder through a three-way pipe. The other input end of the three-way solenoid valve is connected to the output end of the boosting pump. The output end of the three-way solenoid valve is connected to one end of the main gas pipe.

8. The downhole distributed optical fiber airbag coupling recovery system according to claim 6, characterized in that: A plurality of evenly distributed protrusions are integrally formed and connected on the inner circle wall of the airbag.

9. The downhole distributed optical fiber airbag coupling recovery system according to claim 6, characterized in that: The two ends of the "C"-shaped bracket are fixed to the inner circle wall of the airbag by vulcanization, and the optical cable is clamped between the "C"-shaped bracket and the inner circle wall of the airbag and bent to form a double-strand structure.

10. Application of a downhole distributed optical fiber airbag coupling recovery method and device in the field of earthquake detection.

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