WO2021026961A1

WO2021026961A1 - Self-adaptive gas release rod and shallow gas controlled gas release recovery system and method

Info

Publication number: WO2021026961A1
Application number: PCT/CN2019/102106
Authority: WO
Inventors: 王立忠; 赵爽; 洪义; 朱连根; 王强; 茅奇辉
Original assignee: 浙江大学
Priority date: 2019-08-12
Filing date: 2019-08-23
Publication date: 2021-02-18
Also published as: CN110578498B; CN110578498A

Abstract

Disclosed are a self-adaptive gas release rod (4) and a shallow gas controlled gas release recovery system and method. The self-adaptive gas release rod (4) comprises a second hollow feeler lever (39) and a first hollow feeler lever (40); the second hollow feeler lever (39) is connected to the lower portion of the first hollow feeler lever (40), and the diameter thereof is larger than that of the first hollow feeler lever (40); a circumferential groove is formed in the middle of the second hollow feeler lever (39), a sliding sleeve (23) is arranged in the groove, and the lower end of the sliding sleeve (23) is wedge-shaped; a gas release hole (38) is formed in the upper portion of the groove, the sum of the length of the sliding sleeve (23) and the length of the gas release hole (38) is smaller than the length of the groove, and the length of the sliding sleeve (23) is larger than the length of the gas release hole (38); in an insertion process of the self-adaptive gas release rod (4), the sliding sleeve (23) slides to the upper portion of the groove to cover the gas release hole (38); and in an upward pulling process, the sliding sleeve (23) slides to the lower portion of the groove, the gas release hole (38) is exposed, and gas is discharged by means of the gas release hole (38). The recovery system and method based on the self-adaptive gas release rod (4) are used to solve the problem of a rod being blocked by sludge in traditional shallow gas release technology; and a probe can be recovered by means of the integrated design, the shallow gas release cost is reduced, and same is suitable for industrial application.

Description

Adaptive deflation rod and shallow gas controlled deflation recovery system and method

Technical field

The invention relates to an adaptive deflation rod and a shallow gas controlled deflation recovery system and method, which can realize the controlled deflation and recycling of shallow gas, and simultaneously obtain the in-situ mechanical parameters and in-situ mechanical parameters of the soil Measurement of methane concentration.

Background technique

A large amount of organic matter is contained in coastal soft soil. Under long-term closed conditions, microorganisms convert organic matter in coastal soft soil into methane gas, which accumulates and seals underground for a long time to form shallow gas.

Shallow gas is widely distributed in coastal soft soils on five continents in the world. Shallow gas is easy to cause disasters and seriously threatens the underground construction of coastal cities. Due to the "sea advancing and retreating" since the Quaternary, a large number of shallow gas geological disasters have occurred in coastal soft soils along the coastline of my country's southeast coast. For example, in the construction of the Hangzhou Bay Bridge, shallow gas eruptions were encountered many times; shallow gas eruptions were frequently encountered during the construction of Hangzhou Metro Line 1.

At present, the most effective way to deal with shallow gas is to release the shallow gas in advance during the preliminary survey. At present, the release of shallow gas in Hangzhou is uncontrolled deflation. This deflation technology will cause a greater impact on the formation. Disturbance, judging from the results of previous surface displacement monitoring, uncontrolled deflation often causes excessive surface settlement and endangers the "health" of surrounding buildings. The controlled deflation can effectively solve the problem of excessive disturbance.

Prediction of the location of shallow gas reservoirs is the key to early gas release. The presence of shallow gas often changes the mechanical parameters of the surrounding formations. The in-situ mechanical parameters of the soil can be judged by measuring the cone tip resistance, sidewall friction resistance, and pore water pressure when the probe is pressed into the formation. The location of the gas reservoir. At the same time, the methane concentration of shallow gas is an index for evaluating shallow gas, but at present, the methane concentration is obtained through indoor tests after collecting the gas on site, and there are few direct detection of methane concentration on site. In shallow gas formations, the deflation process of shallow gas and the in-situ survey process are separated, which will greatly increase the workload of shallow gas deflation and survey. The integrated equipment of controlled degassing and in-situ survey of shallow gas needs to be developed.

Summary of the invention

The purpose of the present invention is to provide an adaptive deflation rod and a controlled deflation recovery system and method for shallow gas in view of the deficiencies of the prior art.

The present invention adopts the following technical solutions: an adaptive deflation rod, comprising a second hollow probe rod and a first hollow probe rod; the second hollow probe rod is connected to the lower part of the first hollow probe rod and has a diameter larger than that of the first hollow rod The probe rod; the second hollow probe rod is provided with a groove along the circumferential direction in the middle, the groove is provided with a sliding sleeve, and the lower end of the sliding sleeve is wedge-shaped; and the upper part of the groove is opened with a vent hole, a sliding sleeve and a vent hole The sum of the lengths is less than the length of the groove, and the length of the sliding sleeve is greater than the length of the vent hole; in the process of inserting the adaptive deflation rod, the sliding sleeve slides to the upper part of the groove to cover the vent hole; when pulling up, the sliding sleeve slides to the concave In the lower part of the tank, the vent hole is exposed, and the gas is released through the vent hole.

Further, the vent holes are waist holes arranged vertically. On the one hand, the waist hole can increase the deflation area, and on the other hand, it can reduce the excessive reduction of the rigidity of the hollow probe.

The present invention also provides a shallow gas controlled deflation recovery method based on the measurement of soil mechanical parameters. The method is implemented based on the above-mentioned adaptive deflation rod and includes the following steps:

(1) Insert the self-adaptive deflation rod into the shallow gas-containing soil layer, and at the same time collect the penetrating cone tip resistance, side wall friction resistance and pore water pressure of the inserted soil layer;

(2) According to the penetrating cone tip resistance, side wall friction resistance and pore water pressure collected in step (1), the gas-bearing sand lens is identified.

(3) Further insert the self-adaptive deflation rod, and identify the aerated sandy lens in real time until the depth of the soil layer without the aerated sandy lens or the depth of the building foundation.

(4) Pull up the adaptive deflation lever to release shallow gas.

Further, the method also controls the deflation speed through a gas mass flow controller, which communicates with the second hollow probe and the central hole of the first hollow probe through a pipeline.

Further, the gas-cement mixture discharged from the central hole of the second hollow probe rod and the first hollow probe rod is first passed through the separating device to separate the muddy water, and then the gas is input to the gas mass flow controller.

Further, the method also includes gas recovery, specifically: the gas flowing out of the gas mass flow controller is pressurized by a supercharger and then input to the gas storage tank.

The present invention also provides a shallow gas controlled deflation recovery system based on the measurement of soil mechanics parameters, including the above-mentioned adaptive deflation rod, which is used for inserting the hydraulic loading system of the adaptive deflation rod, and is used to collect adaptive The in-situ survey system of cone tip resistance, side wall friction resistance, and pore water pressure is inserted into the deflation rod insertion point. It is used to separate the gas-cement separation system of the self-adaptive deflation rod’s gas-cement mixture. A gas flow servo system for controlling the rod gas release rate, and a gas recovery system for gas recovery.

The above-mentioned hydraulic loading system may include reaction anchors, hydraulic loading heads, fixed holes, reaction frames, etc. The reaction anchors are buried in the ground to provide reaction force for the device, and the fixed holes are used to ensure the vertical penetration of the hollow probe. The reaction frame is used to apply vertical pressure to the probe to press the probe into the formation, and the whole is used to ensure the vertical penetration of the probe.

Further, the in-situ survey system may include a circular cone tip, a deformed column, a friction barrel, a pressure sensor, a pore pressure sensor, a permeable stone, a circuit tube, a battery tube, a hollow probe, etc. The circular cone tip and The auxiliary pressure sensor is arranged at the connection of the pore probe to realize the measurement of the resistance of the cone tip when the probe is pressed into the soil. The main pressure sensor is installed above the friction barrel. During the process of pressing down, the difference between the main pressure sensor and the auxiliary pressure sensor is The side wall friction resistance during the downward pressure of the probe can be obtained. A permeable stone and a pore pressure sensor are installed at the cone shoulder. The permeable stone is used to prevent mud and water from blocking the pore pressure sensor. The pore pressure sensor is used to measure the pressure during the downward pressure process. The pore water pressure can be obtained through the in-situ indentation test to obtain the cone shoulder resistance, the side wall friction resistance, and the pore water pressure. The in-situ soil mechanical parameters can be inversely calculated through three parameters, and the upper part is connected to the in-situ storage system , To realize the wireless collection of the in-situ parameters of the soil, and the battery tube is connected to it to supply power to the lower sensor and the original storage.

The gas flow servo system may include a gas mass flow controller, a mobile power supply, a transformer, a notebook computer, etc. The gas mass flow meter is connected to the top gas outlet of the sedimentation tank, and the mobile power supply and a transformer provide power for the gas mass flow meter , The gas mass flow meter is connected to a laptop computer, which is used to set the maximum allowable deflation rate and collect the shallow gas deflation rate in real time.

The gas, water, and mud separation system includes a sedimentation tank, a barometer, a bottom air inlet, a top air outlet, a silt discharge port, a methane concentration detection probe, etc. The probe is fed through the air pipe and the bottom of the sedimentation tank. Valve connection, the top air outlet and the gas servo system are connected by a gas pipe, the top of the sedimentation tank is connected with a barometer, and the barometer is connected with a data acquisition instrument, which is used to read and store the pressure of the shallow gas reservoir in real time. The methane concentration is installed inside the sedimentation tank. Detection probe for real-time monitoring and collection of methane concentration in shallow gas.

The gas recovery system includes a booster and a gas storage tank. The inlet section of the booster is connected to the outlet end of the gas mass flow controller. The booster is used to increase the pressure of the gas, and the boosted gas enters In the gas storage tank, the recovery and utilization of methane gas is realized.

The beneficial effects of the present invention are:

1. The adaptive deflation rod is used to solve the problem of silt plugging in the traditional shallow gas release technology. On the other hand, the integrated design solves the problem of the traditional deflation method (probe separation type) that the probe cannot be recovered It reduces the cost of shallow gas release and is suitable for industrial applications.

2. The excessively fast release rate of shallow gas will lead to surface subsidence, and the use of controlled venting can effectively control surface subsidence. On the one hand, the recovery of shallow gas prevents methane from polluting the air, and on the other hand, it is effectively recycled as a resource.

Description of the drawings

Figure 1 is a schematic diagram (front view) of the shallow gas controlled deflation recovery system based on the measurement of soil mechanical parameters of the present invention;

Figure 2 is a schematic diagram of the structure of the in-situ survey system (front view);

Figure 3 is a schematic diagram of the structure of an in-situ controlled deflation system (front view);

Figure 4 is a schematic diagram of the structure of the cement separation system (front view);

Figure 5 is a schematic diagram of the structure of the sedimentation tank (cross-sectional view);

Among them, 1. In-situ survey system, 2. Circuit tube, 3. Battery tube, 4. Adaptive deflation rod, 5. Reaction anchor, 6. Sleeper, 7. Fixing hole, 8. Reaction frame, 9. Control system, 10. Three-way valve, 11. Valve, 12. Sedimentation tank, 13. Bottom air inlet, 14. Battery, 15. Transformer, 16. Top air outlet, 17. Laptop, 18. Gas mass flow Controller, 19. Flow meter outlet, 20. Silt discharge port, 21. Booster, 22. Gas tank, 23. Sliding sleeve, 24. Reducer joint, 25. Barometer, 26. Methane concentration sensor, 27. Round cone tip, 28. Permeable stone, 29. Pore pressure sensor, 30. Friction tube, 31. Deformation column, 32. Pressure sensor, 33. Waterproof rubber pad, 34. Hot-swappable joint one, 35. Hot Plug connector two, 36. Outer tube, 37. Wire, 38. Vent hole, 39. Second hollow probe rod, 40. First hollow probe rod, 41. Data acquisition instrument, 42. Internal thread interface.

detailed description

The present invention provides an adaptive deflation rod, as shown in FIG. 3, comprising a second hollow probe rod 39 and a first hollow probe rod 40; the second hollow probe rod 39 is connected to the lower part of the first hollow probe rod 40, And the diameter is larger than the first hollow probe 40; the middle of the second hollow probe 39 is provided with a groove along the circumferential direction, the groove is provided with a sliding sleeve 23, and the lower end of the sliding sleeve 23 is wedge-shaped; and the upper part of the groove There is a vent hole 38, the sum of the length of the sliding sleeve 23 and the vent hole 38 is less than the length of the groove, and the length of the sliding sleeve 23 is greater than the length of the vent hole 38; during the insertion of the adaptive deflation rod, due to the side wall friction, the sliding The sleeve 23 slides to the upper part of the groove to cover the air release hole 38; during the pulling up process, the sliding sleeve 23 slides to the lower part of the groove, the air release hole 38 is exposed, and the air is released through the air release hole. On the one hand, this self-adaptive deflation rod prevents sludge from blocking the rod. On the other hand, it adopts an integrated design, which perfectly solves the problem that the probe of the traditional separate probe cannot be recovered, and reduces the cost of shallow gas release. The deflation rod can be widely used in the field of surveying (in-situ collection of groundwater) and the field of oil exploitation.

Preferably, the vent hole 38 is a waist hole arranged vertically.

Based on the above-mentioned adaptive deflation rod, the present invention provides a device that can simultaneously realize soil mechanical parameter measurement and methane concentration prediction and shallow gas controlled deflation recovery device. Referring to Figure 1, including the above-mentioned adaptive deflation rod, The hydraulic loading system for inserting the adaptive deflation rod is used to collect the penetration cone resistance, sidewall friction resistance and pore water pressure at the insertion point of the adaptive deflation rod. It is used to separate the adaptive deflation rod. A gas-cement separation system that releases gas-cement mixtures, a gas flow servo system that controls the gas release rate of an adaptive gas release rod, and a gas recovery system for gas recovery.

The in-situ survey system is shown in Figure 2. It includes a circular cone tip 27, a permeable stone 28, a pore pressure sensor 29, a friction cylinder 30, a deformation column 31, a pressure sensor 32, a rubber pad 33, a hot plug connector 34, and a thermal Plug-in connector two 35, circuit tube 2, battery tube 3, outer sleeve 36, etc. The pore pressure sensor 29 is installed on the inner side of the permeable stone 28, which is installed on the top of the circular cone tip 27, the deformation column 31 is installed inside the friction cylinder 30, the rubber pad 33 is installed on the top of the friction cylinder 32, and the pressure sensor 33 is installed on the Inside the rubber pad 33, the circuit tube 2 and the in-situ survey probe 1 are connected by a hot-plug connector 34, the circuit tube 2 and the battery tube 3 are connected by a hot-plug connector 35, and the top of the battery tube 3 is welded with a threaded borrow The interface is used to connect to the shallow gas in-situ deflation system.

The self-adaptive deflation rod is connected to the in-situ survey system through the reducing joint 24 at the bottom;

The servo loading system consists of a reaction anchor 5, a sleeper 6, a fixing hole 7, a reaction frame 8, a control system 9, a three-way valve 10 and a valve 11. As shown in Figures 4 and 5, the gas-cement separation system includes a sedimentation tank 12 and a data acquisition instrument 41; the sedimentation tank includes a bottom air inlet 13, a silt drain 20, and a top air outlet 16. The reaction anchor 5 is buried in the ground to provide a reaction force for the servo system. The adaptive deflation rod 4 is fixed at a predetermined position through a fixing hole 7, and the sleeper 6 is installed at the bottom of the reaction frame to provide support for the servo system, and the control system 9 is used to control the servo pressure. The three-way valve 10 is installed on the top of the first hollow probe 40, the upper end is connected to the valve 11, the right end is connected to the air pipe, and the other end of the air connection pipe is connected to the bottom air inlet 13 on the sedimentation tank 12. A methane concentration sensor 29 is installed in the sedimentation tank 12, and a barometer 25 is installed at the top. The methane concentration sensor 26 is used to monitor the methane concentration. The barometer 25 is connected to the data acquisition instrument 41 to monitor and store the shallow gas pressure. When the shallow gas is controlled to release the sprayed gas, water, and mud through the adaptive gas release rod and is introduced into the sedimentation tank 12 of the gas cement separation system through the three-way valve 11, the gas will enter the air flow servo from the top outlet 16 In the system, when the water and sludge accumulate to a certain amount, the sedimentation tank 12 is discharged through the silt discharge port 20. When the first hollow probe rod 40 is blocked by silt, an air compressor can be used to blow high pressure air into it through the upper end of the three-way valve 10 to dredge the first hollow probe rod 40 so that the adaptive deflation rod can resume normal operation.

The gas flow servo system includes a gas mass flow controller 18, a battery 14, a transformer 15, a notebook computer 17, and so on. The gas outlet 16 at the top of the sedimentation tank 12 is connected to a gas mass flow meter 18 through a pipeline, and the gas mass flow meter 18 controls the gas release speed to realize the controlled gas release of the entire device. The storage battery 14 and the transformer 15 jointly supply power to the gas mass flow controller 18, and the notebook computer 17 controls the allowable flow rate. In order to observe the flow characteristics, the gas quality controller can be replaced with a gas mass flow meter, and the computer is used to collect air flow data in real time.

When the released gas is relatively pure, there is no need to connect the gas-cement separation system, and the gas mass flow controller 18 is directly connected to the central holes of the second hollow probe 39 and the first hollow probe 40 through a pipeline to achieve gas mass flow The controller 18 controls the deflation speed.

In addition, the gas recovery system is composed of a supercharger 21 and a gas storage tank 22. The gas inlet of the supercharger 21 is connected to the gas outlet of the gas mass flow meter 18, and the gas outlet is connected to the gas storage tank 22. The gas released by the holes increases the airflow pressure to a certain level by the booster 21 and then is pressed into the gas storage tank 22 for storage.

The following briefly describes the test process using the device of the present invention:

①The adaptive deflation rod 4 is connected to the in-situ survey system through the reducing joint 24 at the bottom, and the in-situ survey system is connected to the computer. After sending the command, the in-situ survey system starts to perform penetration cone tip resistance, sidewall friction resistance, Pore water pressure data collection, identification of gas-bearing sand lens; self-adaptive deflation rod hydraulic loading system fixed hole 7 fixed position.

②Adapt the pressure of the deflation rod 4 through the hydraulic loading system, and recognize the air-bearing sandy lens in real time until the depth of the soil layer without the air-bearing sandy lens or the depth of the building foundation. In this embodiment, since each probe rod is 1 meter long, it is pressed down 1 meter each time until it is pressed into a depth of 35 meters.

③Start to pull out the probe rod and observe whether there is gas, water or mud eruption at the end of the rod. When the eruption occurs, connect the three-way valve 11 and valve 10 to the sedimentation tank 12 of the gas flow servo system. The gas pressure value and the methane concentration value are detected by the barometer 25 and the methane concentration sensor 29, the gas flow is controlled by the gas mass flow meter 18, and the gas is recovered by the gas recovery system.

④When the airflow decreases to 0, disconnect the three-way valve and continue to pull up the probe. When shallow gas appears again, repeat steps ② and ③ until the probe is completely pulled up.

⑤ Disassemble the equipment and prepare for the controlled deflation of the next hole.

After the test, separate the systems and prepare the next set of tests.

Claims

An adaptive deflation rod, comprising a second hollow probe (39) and a first hollow probe (40); the second hollow probe (39) is connected to the lower part of the first hollow probe (40), and The diameter is larger than the first hollow probe (40); the second hollow probe (39) is provided with a circumferential groove in the middle, the groove is provided with a sliding sleeve (23), and the lower end of the sliding sleeve (23) It is wedge-shaped; and the upper part of the groove has a vent hole (38), the sum of the length of the sliding sleeve (23) and the vent hole (38) is less than the length of the groove, and the length of the sliding sleeve (23) is greater than the length of the vent hole (38); In the process of inserting the adaptive air release rod, the sliding sleeve (23) slides to the upper part of the groove to cover the air release hole (38); when the sliding sleeve (23) slides to the lower part of the groove, the air release hole (38) is exposed , And deflate through the vent hole.
The deflation rod according to claim 1, wherein the deflation hole 38 is a waist hole arranged vertically.
A controlled deflation recovery method for shallow gas based on measurement of soil mechanical parameters, characterized in that the method is implemented based on the adaptive deflation rod of claim 1, and comprises the following steps:

(1) Insert the self-adaptive deflation rod into the shallow gas-containing soil layer, and at the same time collect the penetrating cone tip resistance, side wall friction resistance and pore water pressure of the inserted soil layer;

(2) According to the penetrating cone tip resistance, sidewall friction resistance and pore water pressure collected in step (1), identify the gas-containing sand lens;

(3) Further insert the adaptive deflation rod, and identify the air-containing sandy lens in real time until the depth of the soil layer without air-containing sandy lens or the depth of the building foundation;

(4) Pull up the adaptive deflation lever to release shallow gas.
The method according to claim 3, characterized in that the method further controls the degassing speed through a gas mass flow controller 18, and the gas mass flow controller (18) is connected to the second hollow probe (39) through the pipeline. ), the central hole of the first hollow probe (40) is connected.
The method according to claim 4, characterized in that the gas-cement mixture released from the central hole of the second hollow probe (39) and the first hollow probe (40) is first passed through a separation device to separate the muddy water, and then the gas is input To the gas mass flow controller (18).
The method according to claim 4, characterized in that the method further comprises gas recovery, specifically: the gas flowing out of the gas mass flow controller (18) is pressurized by a supercharger and then input to the gas storage tank.
A controlled deflation recovery system for shallow gas based on the measurement of soil mechanical parameters, which is characterized in that it comprises the adaptive deflation rod according to claim 1, which is used to insert the hydraulic loading system of the adaptive deflation rod. An in-situ survey system for collecting cone tip resistance, sidewall friction resistance, and pore water pressure at the insertion point of the self-adaptive deflation rod to separate the gas-cement separation system of the self-adaptive deflation rod for gas-cement mixture. A gas flow servo system that controls the rate of self-adaptive deflation rod gas release, and a gas recovery system for gas recovery.