阅读说明：本技术 一种深部地热开发地温场及位移场综合测试模型试验系统 (Deep geothermal development geothermal field and displacement field comprehensive test model test system ) 是由 贾超 丁朋朋 王辉 狄胜同 马宏源 卫如春 于 2021-06-16 设计创作，主要内容包括：本发明公开了一种深部地热开发地温场及位移场综合测试模型试验系统,包括伺服系统和箱体,所述箱体上设有滑轨,所述伺服系统安装在滑轨上；所述箱体内设有热水储水夹层,所述热水储水夹层内层壁上设有小孔,所述热水储水夹层与填土之间设有过滤筛网,所述箱体内的填土中设有回灌井、开采井、压力传感器和温度传感器。其优点在于,可以同时模拟地热开采过程中水热传递及土层变形特性。(The invention discloses a comprehensive test model test system for a geothermal development geothermal field and a displacement field in a deep part, which comprises a servo system and a box body, wherein the box body is provided with a slide rail, and the servo system is arranged on the slide rail; the hot water recovery device is characterized in that a hot water storage interlayer is arranged in the box body, small holes are formed in the inner wall of the hot water storage interlayer, a filter screen is arranged between the hot water storage interlayer and the filling soil, and a recharge well, a production well, a pressure sensor and a temperature sensor are arranged in the filling soil in the box body. The method has the advantages that the method can simultaneously simulate the water heat transfer and soil layer deformation characteristics in the geothermal exploitation process.)

1. A comprehensive test model test system for a geothermal development geothermal field and a displacement field is characterized by comprising a servo system and a box body, wherein the box body is provided with a slide rail, and the servo system is arranged on the slide rail; the hot water recovery device is characterized in that a hot water storage interlayer is arranged in the box body, small holes are formed in the inner wall of the hot water storage interlayer, a filter screen is arranged between the hot water storage interlayer and the filling soil, and a recharge well, a production well, a pressure sensor, a pore water pressure sensor and a temperature sensor are arranged in the filling soil in the box body.

2. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 1, wherein the box body is provided with a reaction frame, the bottom of the servo system passes through the reaction frame and is fixedly connected with a loading plate, and the loading plate is positioned above the filling soil; the top of the servo system is fixed on the reaction frame through the upright post.

3. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 1, wherein the hot water storage interlayer is provided with a heating pipe and a temperature sensor; the box body is provided with an air outlet and a water outlet which are respectively positioned above and below the hot water storage interlayer, the side surface of the box body is provided with an observation window, and one side corresponding to the hot water storage interlayer is provided with a water filling port.

4. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 1, wherein the recharge well and the production well are made of acrylic glass tubes, water inlets are formed in the middle lower parts of the recharge well and the production well, and partial wrapping gauze screens with the water inlets are arranged on the recharge well and the production well.

5. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 1, wherein the top of each of the production well and the recharge well is provided with a shrinkage cavity joint, the recharge well is connected with a water supply pipe through the shrinkage cavity joint, and the production well is connected with a peristaltic pump through the shrinkage cavity joint.

6. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 1, wherein the filter screen comprises n layers, holes on two adjacent filter screens are alternately distributed, and the diameter D of each layer of holes_nThe following constraints are satisfied:

the filtering screen close to one side of the filling is a first layer of filtering screen.

7. The deep geothermal development geothermal field and displacement field comprehensive test model test system of claim 6, wherein the number P of holes of each layer of filter screen is fitted by software,

P＝2ⁿ-2(n-1)

the filtering screen close to one side of the filling is a first layer of filtering screen.

8. The deep geothermal development geothermal field and displacement field comprehensive test model test system according to claim 1, characterized in that a thermal insulation layer is wrapped outside the box body, and a pressure sensor, a temperature sensor, a pore water pressure sensor and a layered settlement mark in the box body are all connected with a strain data acquisition instrument.

9. The deep geothermal development geothermal field and displacement field comprehensive test model test system according to any one of claims 1 to 8, characterized in that the concrete implementation steps are as follows:

the method comprises the following steps that firstly, a geothermal exploitation well and a recharge well are arranged in a box body, sandy soil is laid in a model test box to serve as a heat storage aquifer medium, a temperature sensor and a pore water pressure sensor are buried, and the height of the laid sandy soil is the same as that of a water storage interlayer; then putting saturated clay on the sandy soil layer to serve as a cover layer of the heat storage water-bearing layer, laying clay in layers, and burying a soil pressure sensor and a temperature sensor; embedding the layered settlement mark for displacement observation into the soil layer to monitor the soil layer settlement condition at any time;

adjusting the position of the reaction frame to ensure that the loading plate is just above the filled soil, and screwing bolts on two sides of the reaction frame;

opening a servo system, slowly descending the loading plate until the loading plate is contacted with the surface of the clay layer, and then stopping descending, and continuously maintaining the pressure at the moment to uniformly apply the pressure on the upper surface of the model soil layer;

opening two exhaust holes on the upper side of the hot water storage interlayer, and slowly injecting hot water into the hot water storage interlayer from the left side and the right side of the box body and a pipeline on the rear side until a preset water level is reached; in the process of injecting hot water, the auxiliary heating equipment is started at the same time, so that the heating pipe of the hot water storage interlayer starts to work;

connecting the production well with a peristaltic pump, starting the peristaltic pump, pumping hot water in the box body through the peristaltic pump, and simultaneously injecting cold water into the box body through a recharging well at a certain pressure; in the process of geothermal exploitation and recharge, the deformation condition of a soil layer is monitored through a settlement mark, the change conditions of soil pressure and pore water pressure in the soil layer are analyzed through a strain acquisition instrument connected with a pressure sensor and a pore water pressure sensor, and the internal heat transfer mechanism in the process of geothermal water exploitation and recharge is known through the strain acquisition instrument connected with a temperature sensor.

Technical Field

The invention belongs to the technical field of environmental geotechnical engineering, and particularly relates to a comprehensive test model test system for a deep geothermal development geothermal field and a displacement field.

Background

The water level of the sandstone heat storage underground water is continuously reduced due to large-scale development and utilization of the geothermal water. The geothermal fluid is weak in supply and low in regeneration capacity, and belongs to a consumption type geothermal resource. The dynamic characteristics of underground hot water are greatly influenced by artificial mining, and the water level of the geothermal water is in a continuous descending trend for years. With the further development and utilization of geothermal resources, the geothermal water level will continuously drop. Therefore, the method has important significance in carrying out the physical model test of the influence of geothermal exploitation recharge on ground subsidence. Meanwhile, due to the fact that the burial depth of the thermal reservoir is large, the understanding of the heat transfer mechanism in the process of geothermal well exploitation and recharge is particularly important through model tests. The test device can effectively simulate the influence of deep geothermal development on the surrounding geological environment, and can provide technical support for the formulation of a geothermal exploitation scheme and the prevention and control of ground subsidence disasters.

In recent years, although a lot of researches are carried out in the fields of geothermal exploitation methods, exploitation simulation efficiency optimization methods and exploitation well structure optimization, a test device and a test method which accurately consider the ground stress on the upper part of a thermal reservoir and can simultaneously simulate the water heat transfer and soil deformation characteristics in the geothermal exploitation process are not available.

Disclosure of Invention

Based on the above problems, the present application provides a comprehensive test model test system for deep geothermal development geothermal field and displacement field, which comprises,

a geothermal development geothermal field and displacement field comprehensive research model test device comprises a servo system and a box body, wherein the box body is provided with a slide rail, and the servo system is arranged on the slide rail; the hot water recovery device is characterized in that a hot water storage interlayer is arranged in the box body, small holes are formed in the inner wall of the hot water storage interlayer, a filter screen is arranged between the hot water storage interlayer and the filling soil, and a recharge well, a production well, a pressure sensor, a pore water pressure sensor and a temperature sensor are arranged in the filling soil in the box body.

Preferably, the box body is provided with a reaction frame, the bottom of the servo system penetrates through the reaction frame to be fixedly connected with a loading plate, and the loading plate is positioned above the filling soil; the top of the servo system is fixed on the reaction frame through the upright post.

Preferably, the hot water storage interlayer is provided with a heating pipe and a temperature sensor; the box body is provided with an air outlet and a water outlet which are respectively positioned above and below the hot water storage interlayer, the side surface of the box body is provided with an observation window, and one side corresponding to the hot water storage interlayer is provided with a water filling port.

Preferably, the recharge well and the production well are made of acrylic glass tubes, water inlet holes are formed in the middle lower parts of the recharge well and the production well, and the recharge well and the production well are partially wrapped with gauze screens provided with the water inlet holes.

Preferably, the top parts of the production well and the recharge well are respectively provided with a shrinkage cavity joint, the recharge well is connected with a water supply pipe through the shrinkage cavity joint, and the production well is connected with a peristaltic pump through the shrinkage cavity joint.

Preferably, the filter screen comprises n layers, the holes on two adjacent filter screens are alternately distributed, and the diameter D of each layer of holes_nThe following constraints are satisfied:

the filtering screen close to one side of the filling is a first layer of filtering screen.

Preferably, the number P of holes of each layer of the filter screen is fitted by software,

P＝2ⁿ-2(n-1)

the filtering screen close to one side of the filling is a first layer of filtering screen.

Preferably, the outer side of the box body is wrapped with a heat insulation layer, and a pressure sensor, a temperature sensor, a pore water pressure sensor and a layered settlement mark in the box body are all connected with a strain data acquisition instrument.

A test system for comprehensive test models of a deep geothermal development geothermal field and a displacement field comprises the following concrete implementation steps:

the method comprises the following steps that firstly, a geothermal exploitation well and a recharge well are arranged in a box body, sandy soil is laid in a model test box to serve as a heat storage aquifer medium, a temperature sensor and a pore water pressure sensor are buried, and the height of the laid sandy soil is the same as that of a water storage interlayer; then putting saturated clay on the sandy soil layer to serve as a cover layer of the heat storage water-bearing layer, laying clay in layers, and burying a soil pressure sensor and a temperature sensor; embedding the layered settlement mark for displacement observation into the soil layer to monitor the soil layer settlement condition at any time;

adjusting the position of the reaction frame to ensure that the loading plate is just above the filled soil, and screwing bolts on two sides of the reaction frame;

opening a servo system, slowly descending the loading plate until the loading plate is contacted with the surface of the clay layer, and then stopping descending, and continuously maintaining the pressure at the moment to uniformly apply the pressure on the upper surface of the model soil layer;

opening two exhaust holes on the upper side of the hot water storage interlayer, and slowly injecting hot water into the hot water storage interlayer from the left side and the right side of the box body and a pipeline on the rear side until a preset water level is reached; in the process of injecting hot water, the auxiliary heating equipment is started at the same time, so that the heating pipe of the hot water storage interlayer starts to work;

connecting the production well with a peristaltic pump, starting the peristaltic pump, pumping hot water in the box body through the peristaltic pump, and simultaneously injecting cold water into the box body through a recharging well at a certain pressure; in the process of geothermal exploitation and recharge, the deformation condition of a soil layer is monitored through a settlement mark, the change conditions of soil pressure and pore water pressure in the soil layer are analyzed through a strain acquisition instrument connected with a pressure sensor and a pore water pressure sensor, and the internal heat transfer mechanism in the process of geothermal water exploitation and recharge is known through the strain acquisition instrument connected with a temperature sensor.

Advantageous effects

1. The characteristics of water heat transfer and soil layer deformation in the geothermal exploitation process can be simulated simultaneously;

2. the test can be repeated to discuss the heat mass transport mechanism under different overlying ground stress, different water temperature, different time and different mining and recharging conditions;

drawings

FIG. 1 is a cross-sectional view of a case;

FIG. 2 is a front view of the case;

FIG. 3 is a schematic structural diagram of the present application;

FIG. 4 is a left side view of the case;

FIG. 5 is a top view of the case.

FIG. 6 is a schematic illustration of a production well configuration;

FIG. 7 is a schematic view of a filter screen structure;

the system comprises a box body, a 2-reaction frame, a 3-hydraulic oil cylinder, a 4-loading plate, a 5-supporting leg, a 6-temperature sensor, a 7-sliding rail, 8-digital display equipment, a 9-servo loading controller, a 10-exhaust hole, an 11-observation window, a 12-exploitation well, a 13-recharge well, a 14-heating pipe, a 15-strain acquisition instrument, a 16-peristaltic pump, a 17-pore water pressure sensor, an 18-hot water storage interlayer, a 20-heat preservation and heat insulation layer, a 21-sand layer, a 22-clay layer, a 23-layered settlement mark, a 24-filter screen, a 25-pressure sensor, a 26-upright post and a 27-water injection port.

Detailed Description

The following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application.

A comprehensive test model test system for a deep geothermal development geothermal field and displacement field comprises a servo system and a box body 1, wherein filling soil is arranged in the box body 1, the filling soil at the bottom is a sand layer 21, and the filling soil at the upper layer is a clay layer 22; the servo system comprises a hydraulic oil cylinder 3 and a servo loading controller 9, a slide rail 7 is arranged on the box body 1, the slide rail 7 extends out of the box body 1 and is fixed on the supporting leg 5, and the hydraulic oil cylinder 3 is arranged on the slide rail 7; a hot water storage interlayer 18 is arranged in the box body 1, small holes of 10mm are formed in the inner wall of the hot water storage interlayer 18, five layers of filtering screens 24 are arranged between the hot water storage interlayer 18 and the sand layer 21, and a recharge well 13, a production well 12, a pressure sensor 25, a pore water pressure sensor 17 and a temperature sensor 6 are arranged in the filled soil in the box body 1.

The servo loading controller 9 realizes servo automatic loading, the precision meets 0.1kPa, the actuator acts on the counter-force beam during loading, and the maximum stroke of the actuator is 400 mm.

The box body 1 is provided with a reaction frame 2, the bottom of the hydraulic oil cylinder 3 penetrates through the reaction frame 2 and is fixedly connected with a loading plate 4, and the loading plate 4 is positioned above the sandy soil layer 21; the top of the hydraulic oil cylinder 3 is fixed on the reaction frame 2 through an upright post 26.

The hot water storage interlayer 18 is provided with a heating pipe 14 and a temperature sensor 6; the box body 1 is provided with an air outlet 10 and a water outlet 1801 which are respectively positioned above and below the hot water storage interlayer 18, the side surface of the box body 1 is provided with an observation window 11, one side corresponding to the hot water storage interlayer 18 is provided with a water injection port 27, and in order to slow down water pressure, the cross-sectional area of the water injection port 27 needs to be larger and occupies 1/8 of the cross-sectional area of the hot water storage interlayer 18.

The geothermal exploitation well and the recharge well pipe are made of acrylic glass pipes, water inlet holes are uniformly drilled in the bottoms of the glass pipes, then sand nets are wrapped on the peripheries of pipe bodies to prevent aquifer sand particles from entering the well pipes to block small holes and damage exploitation pumps, the exploitation well and the recharge well are connected with the tops of the exploitation well and the recharge well through shrinkage joints, the shrinkage joints are connected with water supply pipes of the recharge well, a peristaltic pump is connected with the exploitation well through the shrinkage joints, and recharge equipment used by the recharge well can always inject geothermal tail water with constant pressure into a heat storage confined aquifer in the test process, wherein the pressure water head range is 1.0-4.1 m.

The outer side of the box body 1 is wrapped with a heat insulation layer 20, so that the heat insulation effect is achieved. The pressure sensor 25, the temperature sensor 6, the pore water pressure sensor 17 and the layered settlement mark 23 in the box body 1 are all connected with the strain data acquisition instrument 15.

The water taking section of the geothermal exploitation well in the sandstone thermal storage exploitation region in North and Shandong province is 1321m-1464m, 1200-1464m is taken as a model test research stratum by combining the stratum profile data of the region, wherein 1200-1319m is a thermal storage cover layer, and 1319-1464m is a thermal storage aquifer. The thickness of the heat storage water layer is 145m, the thickness of the upper clay cover layer is 119m, and the crustal stress of more than 1200m is applied to the surface of the heat storage cover layer through a counterforce device after similar theoretical calculation. According to the permeability coefficient of the heat storage aquifer and the average water level depth data of the past year, the influence radius of the geothermal exploitation well is determined to be 160m, the plane size of the model is properly enlarged according to a similar scale, and meanwhile, in order to reduce the influence of the boundary effect on the experimental result, the size of the box body 1 is 1.2m multiplied by 0.8m multiplied by 0.88 m.

Setting upThe geometric similarity scale is 300. According to a similar scale, the thicknesses of the heat-storing aquifer and the cover layer thereof were taken to be 0.48m and 0.40m, respectively. The average gravity of the overburden was taken to be 20kN/m³. In a similar theoretical stress ratio conversion, a compensation load of 20 × 1200 ÷ 300 ÷ 80kPa is required, and this partial load is realized by the ground stress loading device. The annual average water temperature in the heating period of the heat storage aquifer is 52.33-55.08 ℃, and the average value is 54.04 ℃. Keeping the initial temperature of the model and the prototype unchanged, the similarity coefficient of the temperature is 1, and therefore the water temperature in the model heat storage aquifer is determined to be 54 ℃.

The filter screen comprises five layers, the experimental effect is best, as shown in figure 7, the holes on two adjacent layers of filter screens are alternately distributed, and the diameter D of each layer of holes_nThe following constraints are satisfied:

the filtering screen close to one side of the filling is a first layer of filtering screen. The diameter of the mesh of the first layer of filtering screen is 1mm, the diameter of the mesh of the second layer of filtering screen is 4mm, the diameter of the mesh of the third layer of filtering screen is 8mm, the diameter of the mesh of the fourth layer of filtering screen is 16mm, and the diameter of the mesh of the third layer of filtering screen is 32 mm.

Fitting the number P of the holes of each layer of the filter screen by utilizing matlab software,

P＝2ⁿ-2(n-1)

the filtering screen close to one side of the filling is a first layer of filtering screen. The number of the first layer filtering screen holes is 2, the number of the second layer filtering screen holes is 2, the number of the third layer filtering screen holes is 4mm, the number of the fourth layer filtering screen holes is 10, and the number of the fifth layer filtering screen holes is 24.

A geothermal development geothermal field and displacement field comprehensive research model test device comprises the following concrete implementation steps:

step one, firmly arranging a protective wall of a geothermal exploitation well 12 and a recharge well in a model test box body 1, paving a sand layer 21 in the box body 1 as a medium of a hot water storage layer, embedding a temperature sensor 6 and a pressure sensor 25 according to the figure 1 in the soil release process, wherein the height of the sand layer 21 and the height of a hot water storage interlayer 18 are 0.48 m; then, a saturated clay layer 22 is put on the sandy soil layer 21 to be used as a cover layer of the heat storage water-bearing layer, clay is laid in layers until the thickness reaches 0.40m, and the soil pore water pressure sensor 27 and the temperature sensor 6 are buried according to the figure 1. Meanwhile, the layered settlement mark 23 for displacement observation is buried in the soil layer to monitor the soil layer settlement condition at any time.

And step two, adjusting the position of the reaction frame 2 to ensure that the loading plate 4 is just positioned right above the soil body, and screwing the bolts at two sides of the reaction frame 2.

And step three, opening the servo loading controller 9, setting the descending speed of the hydraulic oil cylinder 3 on the digital display device 8, and opening a descending button of the servo loading controller to slowly descend the loading plate 4 until the servo loading controller contacts with the surface of the clay layer 22. And clicking an automatic pressure maintaining function button on the digital display device 8, setting the ground stress of 80kPa, and uniformly applying the ground stress on the upper surface of the model soil layer according to the set pressure of the overburden layer.

And step four, in order to prevent the soil layer structure from being damaged in the hot water injection process of the hot reservoir, opening two exhaust holes 10 on the upper side of the hot water storage interlayer 18, and slowly injecting hot water at 75 ℃ into the box body 1 from the left side and the right side of the model box and the rear side pipeline until the preset water level is reached. In the process of injecting hot water, the auxiliary heating device is started at the same time, so that the heating pipe 14 of the hot water storage interlayer 18 starts to work, the internal temperature of the hot water storage interlayer 18 is maintained at about 54 ℃, and observation is carried out through the observation window 11.

And step five, respectively placing the geothermal exploitation well 12 and the recharge well 13 into the protective walls of the geothermal exploitation well, connecting the exploitation well with a peristaltic pump 16, starting the peristaltic pump 16, pumping hot water in the box body 1 out through the peristaltic pump 16, and simultaneously injecting cold water in a tap water pipeline into the box body 1 through the recharge well at a certain pressure. In the process of geothermal exploitation and recharge, the deformation condition of a soil layer is monitored through a settlement mark, observation is carried out through an observation window 11, the change conditions of soil pressure and pore water pressure in the soil layer are acquired through a strain acquisition instrument 15 connected with a pressure sensor 25 and a pore water pressure sensor 17, and the internal heat transfer mechanism in the process of geothermal water exploitation and recharge is known through the strain acquisition instrument 15 connected with a temperature sensor 6.

And step six, after data acquisition is completed, the hydraulic oil cylinder 3 is lifted when the controller 9 is loaded in a servo mode, the hydraulic oil cylinder 3 moves to the supporting leg position along the sliding rail, and the filled soil is cleaned to carry out the next experiment.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.