WO2022000833A1

WO2022000833A1 - Permafrost formation thawing and subsidence test simulation device and method

Info

Publication number: WO2022000833A1
Application number: PCT/CN2020/118258
Authority: WO
Inventors: 杨进; 王欢欢; 李莅临; 张东昱甫; 汪文星; 赵新; 洪佳瑶
Original assignee: 中国石油大学(北京)
Priority date: 2020-07-03
Filing date: 2020-09-28
Publication date: 2022-01-06
Also published as: CN111679061B; CN111679061A

Abstract

A permafrost formation thawing and subsidence test simulation device and a method. The device comprises: a reaction container (1) provided with a reaction cavity (101); a pressurization assembly (2) and a temperature control assembly (3) connected to the reaction container (1); a confining pressure assembly (4) surrounding a sidewall of the reaction container (1); a simulation conduit system (5) comprising a conduit (501) provided within the reaction cavity (101), and a drilling rod (502) passing through the conduit (501), wherein an annular space (503) is formed between the drilling rod (502) and the conduit (501); a drilling fluid circulation system (6) comprising a drilling fluid storage tank (601), a fluid inlet pipeline (602) communicated with the conduit (501), a fluid return pipeline (603) communicated with the annular space (503), a heating device (604) provided on the fluid inlet pipeline (602), a pressurization pump (605), a switch valve (606), and a filter device (608) provided on the fluid return pipeline (603); a measurement acquisition device (7) communicated with the reaction cavity (101); and a control module connected to the pressurization assembly (2), the temperature control assembly (3), the switch valve (606), and the measurement acquisition device (7). The device can obtain a change pattern of thawing water discharge amounts and formation subsidence amounts in different heating ranges and different heating temperature conditions.

Description

Frozen ground thawing settlement test simulation device and method

Cross-reference related references

This application claims the priority of the Chinese Patent Application No. 202010630011.3 filed on July 3, 2020, and the invention is titled "Simulation Device and Method for Thawing and Settlement Test of Frozen Ground", the entire contents of which are incorporated into this application by reference.

technical field

The invention relates to research equipment for strata thawing and settlement in the exploration and development of permafrost strata, in particular to a device for strata thawing and settlement simulation tests in the process of drilling into permafrost layers, and using the device to conduct permafrost strata thawing and settlement experiments simulated method.

Background technique

Large areas of permafrost are widely developed in the Arctic, sub-Arctic, Qinghai-Tibet Plateau, and Xinjiang in my country. In addition to conventional oil and gas resources, these areas also host a large number of natural gas hydrates, which have great development value. However, permafrost drilling faces enormous technical challenges. Specifically, due to the heat exchange between the drilling fluid and the formation, the frozen soil layer heats up and thaws, and the bearing capacity of the frozen soil drops significantly. The wellhead and surface conduits are prone to instability and sinking under the action of the wellhead load, resulting in interruption of operations. Seriously affect work safety.

At present, some scholars have carried out the numerical simulation of finite element analysis of stratum settlement in the process of drilling into permafrost, but there are only a few studies on the simulation experiments of permafrost strata thawing and settlement. At the same time, there is a lack of research on the correlation between heating range, heating temperature, permafrost thawing water discharge and formation subsidence. Attention should be paid to the prediction of formation subsidence, and there is no simulation of permafrost-containing strata that controls heating temperature and heating range. The subsidence test device is not very accurate in predicting the subsidence of the stratum under different conditions.

SUMMARY OF THE INVENTION

Based on the aforementioned defects of the prior art, the embodiments of the present invention provide a permafrost stratum thawing and settlement test simulation device and method, which can better solve the above problems.

In order to achieve the above objects, the present invention provides the following technical solutions.

A permafrost layer thawing and settlement test simulation device, comprising:

The reaction vessel has a reaction chamber for generating a frozen soil layer and simulating the subsidence of the frozen soil layer, and is provided with a visualization window for a user to observe the internal situation of the reaction chamber; the reaction vessel comprises: a container body with an upper end open, a detachable an upper cover closed on the upper end of the container body; the bottom of the reaction chamber is provided with a filter screen;

a pressurizing assembly, connected with the reaction vessel, for adjusting the pressure inside the reaction chamber;

a temperature control assembly, connected with the reaction vessel, for adjusting the temperature inside the reaction chamber;

a confining pressure component, surrounding the side wall of the reaction vessel, for adjusting the confining pressure inside the reaction chamber;

The simulated conduit system includes: a plurality of conduits arranged in the reaction chamber and inserted into the frozen soil layer, and a plurality of drill pipes correspondingly penetrated in the plurality of conduits; the side walls of the conduits are provided with openings. a hole, an annulus is formed between the corresponding drill pipe and the guide pipe; the bottom of the guide pipe is spaced from the filter screen;

A drilling fluid circulation system, comprising: a drilling fluid storage tank, a liquid inlet pipeline connecting the drilling fluid storage tank and the upper ends of a plurality of the drill pipes, and a liquid return pipeline connecting the drilling fluid storage tank and a plurality of the annuluses , a heating device, a booster pump, an on-off valve and an injection flowmeter arranged on the liquid inlet pipeline, a filter device and an outflow flowmeter arranged on the liquid return pipeline;

a collection and measurement device, communicated with the bottom of the reaction chamber, and used to collect and measure the amount of liquid after the permafrost layer is thawed;

a control module, connected with the pressurizing component, the temperature control component, the on-off valve, the injection flowmeter, the outflow flowmeter and the acquisition and measurement device, for controlling the opening and closing of the pressurizing component, the temperature control component and the on-off valve, and Acquire the flow of the injection flowmeter, the outflow flowmeter, and the acquisition and measurement device.

A method for utilizing the permafrost strata thawing and settlement test simulation device described in the above embodiment, comprising:

Step S1: Remove the upper cover from the upper end of the container body, lay the simulated sand layer evenly on the bottom of the reaction vessel, insert the conduit into the simulated sand layer, and then place the conduit around the conduit. Lay the water-containing sand layer, and then connect the upper cover to the upper end of the container body;

Step S2: controlling the operation of the pressurizing component and the temperature control component, adjusting the pressure and temperature in the reaction vessel, and generating the frozen soil layer;

Step S3: after the completion of the formation of the permafrost layer is observed through the visualization window, the upper cover is opened, the soil layer cover layer is laid on the upper part of the permafrost layer, the compaction is repeated until it is still until it is compacted, and it is left for a predetermined time;

Step S4: Control all on-off valves, booster pumps and heating devices to turn on, inject heated drilling fluid into all conduits, simulate the formation being heated during drilling into the frozen soil layer, collect the liquid produced by the thawing of the frozen soil layer in real time, observe and Record formation subsidence and subsidence amount;

Step S5: After the amount of melted water in the permafrost layer is gradually reduced to the point where no melted water is produced, open the upper cover, repeat the above steps S1 to S3, and change the opening number of the on-off valve and/or the heating temperature of the heating device , simulate the heating of the frozen soil layer under different heating ranges and/or different heating temperature conditions, collect the liquid volume generated by the decomposition of the frozen soil layer in real time, and observe and record the stratum settlement and settlement.

The permafrost strata thawing and settlement test simulation device according to the embodiment of the present invention can obtain the variation law of the permafrost thawing water output and the stratum settlement under different heating ranges and heating temperature conditions, so as to obtain the thermal settlement characteristics of the permafrost-containing stratum, and also It is helpful to study the relationship between heating range, heating temperature, melt water volume and stratum subsidence, and lay a foundation for the next step to establish a prediction model for the subsidence of permafrost-bearing strata and to further improve the prediction accuracy of strata subsidence.

In addition, the embodiments of the present application can change the number of simulated conduit drilling fluid on-off valves and the temperature of the drilling fluid heating device, so as to study the formation subsidence characteristics of permafrost-bearing strata under different heating ranges and heating temperature conditions. The device can collect, process and measure permafrost thaw by setting a collection and measurement device, so as to study the relationship between stratum subsidence and meltwater.

Description of drawings

1 is a schematic structural diagram of a permafrost strata thawing and settlement test simulation device according to an embodiment of the present invention;

Figure 2 is a schematic structural diagram of the assembly of the simulated conduit system and the drilling fluid circulation system.

detailed description

As shown in FIG. 1 and FIG. 2 , the embodiment of the present invention provides a permafrost ground thawing and settlement test simulation device, including: a reaction vessel 1, a pressurizing component 2, a temperature control component 3, a confining pressure component 4, a simulated conduit system 5, Drilling fluid circulation system 6, acquisition and measurement device 7 and control module (not shown).

The reaction vessel 1 is made of materials resistant to high pressure and low temperature, including a container body with an open upper end and an upper cover detachably closed on the upper end of the container body, and the upper cover can be detachably connected to the upper end of the container body through a flange structure. The reaction vessel 1 is equipped with a reaction chamber 101 for generating a frozen soil layer and simulating subsidence of the formation, and the reaction chamber 101 is composed of a container body and an upper cover. The reaction vessel 1 is also provided with a visualization window 102 for a user to observe the internal conditions of the reaction chamber 101 . Specifically, the visualization window 102 is made of high-strength glass and is provided on the side wall of the container body. The bottom of the reaction vessel 1 is provided with a filter screen 104 for filtering soil particles, so that the water melted by the frozen soil layer flows into the collecting and measuring device 7 .

The pressurizing assembly 2 is connected to the reaction vessel 1 for regulating the pressure inside the reaction chamber 101 . Specifically, the pressurizing assembly 2 may include a gas cylinder, an air inlet pipeline connecting the gas cylinder and the reaction vessel 1, and a pressure regulating device provided on the air inlet pipeline. The pressure regulating device includes a booster pump and a pressure regulating valve which are sequentially arranged on the intake pipeline from upstream to downstream along the flow direction of the gas in the intake pipeline. Wherein, the upper cover of the reaction container 1 is reserved with a gas injection port 103, and the two ends of the air inlet pipeline are respectively connected with the gas outlet of the gas cylinder and the gas injection port 103 of the upper cover, so as to realize the communication between the gas cylinder and the reaction container 1, and through The gas cylinder fills the reaction vessel 1 with gas to realize pressure regulation in the reaction chamber 101 .

The reaction vessel 1 is provided with a pressure sensor connected to the control module, and the control module can control the operation of the pressure regulating device based on the pressure detected by the pressure sensor in the reaction vessel 1 . Specifically, according to the magnitude of the actual formation pressure, the actual formation pressure is simulated by filling the reaction chamber 101 with gas. Therefore, a reference pressure value for simulating the actual formation pressure can be set in advance, and by filling the gas, the pressure in the reaction chamber 101 can gradually approach the reference pressure value. When the pressure approaches the reference pressure value, the control module can control the pressure regulating device to slow down the pressure increase speed until the pressure reaches the set reference pressure value, and control the pressure regulating device to stop gas injection into the reaction chamber 101 .

More specifically, at the beginning of gas charging, the control module controls the pressure regulating valve to open, and controls the motor or motor that drives the booster pump to run at a faster speed. In this way, at the beginning of the experiment, the pressure in the reaction chamber 101 increases at a faster rate. When the pressure is close to the target value (reference pressure value), for example, the current pressure is 95% of the reference pressure value, in order to avoid pressure overshoot, the pressure increase speed can be reduced. At this time, the control module can control the motor or motor driving the booster pump to reduce the running speed, and/or control the opening of the pressure regulating valve to reduce, so as to slow down the gas charging flow and reduce the pressure increase speed. Until the actual pressure value in the reaction chamber 101 reaches the target pressure value, the control module controls the motor or motor driving the booster pump to stop, and controls the pressure regulating valve to close, so that the pressure value in the reaction chamber 101 maintains the current pressure value.

The temperature control assembly 3 is connected to the reaction vessel 1 for adjusting the temperature inside the reaction chamber 101 . The temperature control assembly 3 is mainly used to create a low temperature environment in the reaction chamber 101 to generate a frozen soil layer. Specifically, the temperature control assembly 3 includes a refrigeration unit, a water bath jacket surrounding the side wall of the reaction vessel 1, a circulation pipeline connecting the refrigeration unit and the water bath jacket, and a first control valve provided on the circulation pipeline.

Further, the reaction vessel 1 is provided with a temperature sensor connected to the control module, and the control module can control the operation of the refrigeration unit and/or the first control valve based on the temperature detected by the temperature sensor in the reaction vessel 1 . As described above, specifically, according to the actual temperature conditions of the formation of the frozen soil layer, the temperature of the reaction chamber 101 is realized by pumping the refrigerant in the circulation pipeline by the refrigeration unit. Therefore, a reference temperature value (eg -20°C) required for simulating the actual formation of the frozen soil layer can be set in advance, and the temperature in the reaction chamber 101 can be gradually approached to the reference temperature value by controlling the operation of the refrigeration unit. When the temperature approaches the reference temperature value, the control module controls the refrigeration unit and/or the first control valve, slows down the cooling speed, and controls the refrigeration unit to stop working until the temperature reaches the set reference temperature value.

More specifically, at the beginning of refrigeration, the control module controls the opening of the first control valve, and controls the refrigeration unit to operate with a higher power. In this way, at the beginning of the experiment, the temperature in the reaction chamber 101 is rapidly decreased at a faster rate. When the temperature is close to the target value (reference temperature value), for example, the current temperature is 95% of the reference temperature value, in order to avoid temperature overshoot, the cooling speed is reduced. At this time, the control module may control the refrigeration unit to reduce the refrigeration power, and/or control the opening degree of the first control valve to decrease, so as to slow down the refrigerant flow and reduce the cooling speed. Until the actual temperature value in the reaction chamber 101 reaches the target temperature value, the control module controls the refrigeration unit to continue to operate according to the current power, and controls the first control valve to maintain the current opening to maintain the current low temperature in the reaction chamber 101, so that the The resulting permafrost is stable.

The confining pressure component 4 surrounds the side wall of the reaction vessel 1 and is used to adjust the confining pressure inside the reaction chamber 101 to simulate the actual formation confining pressure of the frozen soil layer. Specifically, the confining pressure component 4 includes a hydraulic pump, a motor for driving the hydraulic pump, a deformable rubber sleeve laid in the reaction vessel 1, a hydraulic pipeline connecting the hydraulic pump and the deformable rubber sleeve, a second control valve. The motor and the second control valve are connected with the control module, and the control module controls the operation of the motor and the second control valve. The inlet end of the hydraulic pump is connected to the hydraulic tank for storing hydraulic oil. By pumping hydraulic oil into the deformable rubber sleeve, the deformable rubber sleeve is deformed and the frozen soil layer is squeezed to realize the application of confining pressure.

The upper part of the simulated conduit system 5 is connected to the drilling fluid circulation system 6 through pipelines, and is used to simulate the process of the formation being heated and then melted during the production process. As shown in FIG. 2 , the simulated conduit system 5 includes: a plurality of conduits 501 arranged in the reaction chamber 101 and inserted into the frozen soil layer, and a plurality of drill pipes 502 correspondingly penetrated in the plurality of conduits. The side wall of the conduit 501 is provided with openings, an annulus 503 is formed between the corresponding drill pipe 502 and the conduit 501, and the bottom of the conduit 501 is spaced from the filter screen. That is, the bottom of the conduit 501 is not in contact with the bottom of the reactor 1, but is spaced apart. In this way, the melted water heated by the permafrost layer around the conduit 501 penetrates downward and is discharged through the filter screen 104 . The drill rod 502 is suspended in the conduit 501 , and the specific manner may be that the upper end of the drill rod 502 is fixed on the upper end of the reaction vessel 1 .

The side wall of the conduit 501 is provided with an opening to communicate the conduit 501 and the external space, and the lower end of the drill pipe 502 is opened. In this way, after the drilling fluid subsequently injected into the drill pipe 502 enters the annulus 503 through the lower end opening, it exchanges heat with the permafrost layer outside the conduit 501, so that the permafrost layer is heated and thawed. Part of the water that is heated and melted by the frozen soil layer infiltrates downward and is discharged to the acquisition and measurement device 7, and the other part enters the annular space 503 through the opening, and finally returns upward.

The drilling fluid circulation system 6 includes a drilling fluid storage tank 601, a liquid inlet pipeline 602 connecting the drilling fluid storage tank 601 and the upper ends of the multiple drill pipes 502, a liquid return pipeline 603 connecting the drilling fluid storage tank 601 and the multiple annuluses 503, and a device. Heating device 604 , booster pump 605 , on-off valve 606 and injection flowmeter 607 on the liquid inlet line 602 , filter device 608 and outflow flowmeter 609 on the liquid return line 603 . The heating device 604 is located between the drilling fluid storage tank 601 and the booster pump 605 , the injection flowmeter 607 is located between the booster pump 605 and the switch valve 606 , and the outflow flowmeter 609 is located between the annulus 503 and the filter device 608 . That is, the heating device 604, the booster pump 605, and the injection flowmeter 607 are arranged in sequence along the inflow direction of the drilling fluid, while the outflow flowmeter 609 and the filter device 608 are arranged in sequence along the return direction of the drilling fluid.

In this embodiment, the heating device 604 and the filtering device 608 may adopt any suitable existing structures, which are not limited in this embodiment. For example, the heating device 604 can be a water bath or oil bath heater, an electric heater, etc. set outside the liquid inlet line 602, and the filtering device 608 is a cyclone filter. In actual operation, the drilling fluid stored in the drilling fluid storage tank 601 is pumped into the liquid inlet pipeline 602 under the pumping action of the booster pump 605, heated and heated up when flowing through the heating device 604, and then enters the drill pipe. 502, and is discharged from the lower end of the drill pipe 502 into the annulus 503 to exchange heat with the frozen soil layer, thereby heating the frozen soil layer. The permafrost layer is heated and melted, and part of the water formed penetrates downward and enters and exits to the acquisition and measurement device 7;

Further, the heating device 604 can be controlled by the control module to adjust the temperature. Specifically, for example, the heating device 604 is an electric heater, and the control module controls the output heating temperature by controlling the driving voltage of the heating device 604, thereby adjusting the temperature of the drilling fluid, so as to study the formation under different heating drilling fluid temperatures subsidence.

In this embodiment, the conduits 501 and the drill pipes 502 correspond to each other and the number is multiple. The drilling fluid storage tank 601 is connected to the upper end of each drill pipe 502 through the liquid inlet line 602, and is connected through the on-off valve 606 on each liquid inlet line 602. to control whether the corresponding drill rod 502 operates.

Further, the control module can selectively control one or several of the plurality of on-off valves 606 to close, so that one or several of the plurality of drill rods 502 can perform drilling fluid circulation operation. This is used to simulate the heating and thawing of frozen soil layers under different heating ranges. That is, by changing whether a plurality of drill pipes 502 are filled with liquid, the heating and thawing of the permafrost layer around the corresponding conduit 501 is controlled, so as to study the decomposition of the permafrost layer and the subsidence of the permafrost under different heating conditions.

The collecting and measuring device 7 communicates with the bottom of the reaction chamber 101 and is used for collecting and measuring the amount of liquid after the frozen soil layer is thawed. Specifically, the acquisition and measurement device 7 includes a gas-liquid-solid separator 701 and a storage tank 702 connected to the outlet end of the gas-liquid-solid separator 701 . The inlet end of the gas-liquid-solid separator 701 is communicated with the bottom of the reaction chamber 101 through a collection pipeline, and a collection flowmeter 703 (eg, a flowmeter) is provided on the collection pipeline, and the collection flowmeter 703 is connected to the control module. In this way, the frozen soil layer is heated and melted through the heat exchange with the circulating drilling fluid, and the liquid formed is discharged to the gas-liquid-solid separator 701 through the collection pipeline, and the separated liquid is stored in the storage tank 702 . During the collection process, the collection flow meter 703 measures the liquid formed by the thawing of the permafrost. That is, the collection pipeline collects the melted liquid in the lower part of the filter screen 104, passes through the lower channel of the reaction vessel 1 and the collection flow meter 703, and the melted liquid finally flows into the storage tank 702 for measuring and collecting the melted liquid.

The control module is connected with the pressurizing component 2, the temperature control component 3, the on-off valve 606, the injection flowmeter 607, the outflow flowmeter 609 and the acquisition and measurement device 7, and is used to control the pressure components 2, the temperature control component 3 and the on-off valve 606. Open and close, and obtain the flow of the injection flowmeter 607, the outflow flowmeter 609 and the acquisition and measurement device 7. The control module controls the opening and closing of the pressure component 2 , the temperature control component 3 , and the on-off valve 606 as described above, and will not be repeated here.

By acquiring the flow rates of the injection flowmeter 607 , the outflow flowmeter 609 and the collection and measurement device 7 , the amount of melted water after the permafrost layer is heated and thawed can be acquired. The amount of melt water is calculated as follows:

V _total = (V _{outflow drilling fluid} - V _{inflow drilling fluid} ) + V _{bottom collection}

In the formula: V is the _total amount of melt water in the simulation experiment, V _{outflow drilling fluid} is the upward return volume of circulating drilling fluid measured by the outflow flowmeter 609, V _{inflow drilling fluid} is the circulating drilling fluid injection amount measured by the inflow flowmeter 607 , V _{bottom collection} is the amount of melt water flowing into the bottom of the reaction vessel 1 due to the action of gravity measured by the collection flow meter 703 .

The control module may take the form of, for example, a microprocessor or processor and a computer readable medium storing computer readable program code (eg software or firmware) executable by the microprocessor or processor, logic gates, switches, application specific integrated circuits (Application Specific Integrated Circuit (ASIC), Programmable Logic Controller (PLC) and embedded Microcontroller Unit (MCU), examples of the above modules include but are not limited to the following microcontroller units: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. Those skilled in the art should also know that, in addition to realizing the functions of the control module in the form of purely computer-readable program codes, the control unit can be programmed with logic gates, switches, application-specific integrated circuits, programmable logic gates, switches, special-purpose integrated circuits, programmable logic The same function can be realized in the form of logic controller and embedded microcontroller unit.

In a specific application scenario, when using the permafrost strata thawing settlement test simulation device according to the embodiment of the present invention to conduct a stratum settlement test, the following steps are performed:

Step S1: remove the upper cover from the upper end of the container body, lay the simulated sand layer evenly on the bottom of the reaction vessel 1, insert the conduit 501 into the simulated sand layer, insert the drill pipe 502 into the conduit 501 and fix it, and then place the conduit A water-containing sand layer is laid around the 501, and then the upper cover is connected to the upper end of the container body;

Step S2: control the operation of the pressurizing component 2 and the temperature control component 3, adjust the pressure and temperature in the reaction vessel 1, and generate the frozen soil layer;

Step S3: after it is observed through the visualization window 102 that the formation of the permafrost layer is completed, the upper cover is opened, the soil layer cover layer is laid on the upper part of the permafrost layer, the compaction is repeated until it is still until it is compacted, and it is left to stand for a predetermined time;

Step S4: Control all on-off valves 606, booster pump 605 and heating device 604 to open, inject heated drilling fluid into all conduits 501, simulate the formation being heated in the process of drilling into permafrost layers, and collect in real-time the results of thawing permafrost layers. liquid, observe and record the subsidence of the formation and the amount of subsidence;

Step S5: After the amount of melted water in the permafrost layer is gradually reduced to the point where no melted water is produced, open the upper cover, repeat the above steps S1 to S3, change the opening number of the on-off valve 606 and the temperature of the drilling fluid, and simulate different heating ranges and different heating Under the condition of temperature, the frozen soil layer is heated, and the liquid volume generated by the decomposition of the frozen soil layer is collected in real time, and the subsidence and settlement of the stratum are observed and recorded.

In addition, the embodiment of the present application can change the number of simulated conduit drilling fluid on-off valves 606 and the temperature of the drilling fluid heating device 604, so as to study the formation subsidence characteristics of permafrost-bearing strata under different heating ranges and heating temperature conditions. The device can collect, process and measure permafrost thaw by setting a collection and measurement device, so as to study the relationship between stratum subsidence and meltwater.

The permafrost stratum thawing and settlement test simulation device according to the embodiment of the present invention can be widely used in various fields of permafrost-containing stratum resource exploration and development.

The above are only a few embodiments of the present invention, and those skilled in the art can make various changes or modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention according to the contents disclosed in the application documents.

Claims

A permafrost layer thawing and settlement test simulation device, characterized in that it includes:

The reaction vessel has a reaction chamber for generating a frozen soil layer and simulating the subsidence of the frozen soil layer, and is provided with a visualization window for a user to observe the internal situation of the reaction chamber; the reaction vessel comprises: a container body with an upper end open, a detachable an upper cover closed on the upper end of the container body; the bottom of the reaction chamber is provided with a filter screen;

a pressurizing assembly, connected with the reaction vessel, for adjusting the pressure inside the reaction chamber;

a temperature control assembly, connected with the reaction vessel, for adjusting the temperature inside the reaction chamber;

a confining pressure component, surrounding the side wall of the reaction vessel, for adjusting the confining pressure inside the reaction chamber;

The simulated conduit system includes: a plurality of conduits arranged in the reaction chamber and inserted into the frozen soil layer, and a plurality of drill pipes correspondingly penetrated in the plurality of conduits; the side walls of the conduits are provided with openings. a hole, an annulus is formed between the corresponding drill pipe and the guide pipe; the bottom of the guide pipe is spaced from the filter screen;

A drilling fluid circulation system, comprising: a drilling fluid storage tank, a liquid inlet pipeline connecting the drilling fluid storage tank and the upper ends of a plurality of the drill pipes, and a liquid return pipeline connecting the drilling fluid storage tank and a plurality of the annuluses , a heating device, a booster pump, an on-off valve and an injection flowmeter arranged on the liquid inlet pipeline, a filter device and an outflow flowmeter arranged on the liquid return pipeline;

a collection and measurement device, communicated with the bottom of the reaction chamber, and used to collect and measure the amount of liquid after the permafrost layer is thawed;

a control module, connected with the pressurizing component, the temperature control component, the on-off valve, the injection flowmeter, the outflow flowmeter and the acquisition and measurement device, for controlling the opening and closing of the pressurizing component, the temperature control component and the on-off valve, and Acquire the flow of the injection flowmeter, the outflow flowmeter, and the acquisition and measurement device.
The permafrost ground thawing and settlement test simulation device according to claim 1, wherein the pressurizing assembly comprises: a gas cylinder, an air inlet pipeline connecting the gas cylinder and the reaction vessel, a A pressure regulating device on the gas pipeline; the pressure regulating device includes a booster pump and a pressure regulating valve sequentially arranged on the intake pipeline from upstream to downstream along the flow direction of the gas in the intake pipeline;

The reaction vessel is provided with a pressure sensor connected to the control module, and the control module controls the operation of the pressure regulating device based on the pressure detected by the pressure sensor in the reaction vessel.
The thawing and settlement test simulation device of frozen ground according to claim 1, wherein the temperature control assembly comprises: a refrigeration unit, a water bath jacket surrounding the side wall of the reaction vessel, connecting the refrigeration unit and the water bath a circulating pipeline of the jacket, and a first control valve arranged on the circulating pipeline;

The reaction vessel is provided with a temperature sensor connected to the control module, and the control module controls the operation of the refrigeration unit and/or the first control valve based on the temperature detected by the temperature sensor in the reaction vessel.
The thawing and settlement test simulation device for frozen ground according to claim 1, wherein the confining pressure component comprises: a hydraulic pump, a motor for driving the hydraulic pump, and a deformable rubber sleeve laid in the reaction vessel , a hydraulic pipeline connecting the hydraulic pump and the deformable rubber sleeve, and a second control valve arranged on the hydraulic pipeline;

The motor and the second control valve are connected to the control module, and the control module controls the operation of the motor and the second control valve.
The permafrost ground thawing and settlement test simulation device according to claim 1, wherein the heating device is located between the drilling fluid storage tank and the booster pump, and the injection flowmeter is located at the booster pump. Between the pump and the on-off valve, the outflow flow meter is located between the annulus and the filter device.
The permafrost ground thawing and settlement test simulation device according to claim 1, wherein the control module can selectively control one or several of the plurality of on-off valves to close, so as to make a plurality of the drill pipes One or several of the drilling fluid circulation operations.
The permafrost strata thawing and settlement test simulation device according to claim 1, wherein the acquisition and measurement device comprises: a gas-liquid-solid separator, a storage tank connected to the outlet end of the gas-liquid-solid separator; The inlet end of the gas-liquid-solid separator is communicated with the bottom of the reaction chamber through a collection pipeline, the collection pipeline is provided with a collection flowmeter, and the collection flowmeter is connected to the control module.
A method for utilizing the permafrost strata thawing and settlement test simulation device according to any one of claims 1 to 7, wherein the method comprises:

Step S1: Remove the upper cover from the upper end of the container body, lay the simulated sand layer evenly on the bottom of the reaction vessel, insert the conduit into the simulated sand layer, and then place the conduit around the conduit. Lay the water-containing sand layer, and then connect the upper cover to the upper end of the container body;

Step S2: controlling the operation of the pressurizing component and the temperature control component, adjusting the pressure and temperature in the reaction vessel, and generating the frozen soil layer;

Step S3: after the completion of the formation of the permafrost layer is observed through the visualization window, the upper cover is opened, the soil layer cover layer is laid on the upper part of the permafrost layer, the compaction is repeated until it is still until it is compacted, and it is left for a predetermined time;

Step S4: Control all on-off valves, booster pumps and heating devices to turn on, inject heated drilling fluid into all conduits, simulate the formation being heated during drilling into the frozen soil layer, collect the liquid produced by the thawing of the frozen soil layer in real time, observe and Record formation subsidence and subsidence amount;

Step S5: After the amount of melted water in the permafrost layer is gradually reduced to the point where no melted water is produced, open the upper cover, repeat the above steps S1 to S3, and change the opening number of the on-off valve and/or the heating temperature of the heating device , simulate the heating of the frozen soil layer under different heating ranges and/or different heating temperature conditions, collect the liquid volume generated by the decomposition of the frozen soil layer in real time, and observe and record the stratum settlement and settlement.