Cross-fracture multilayer Rn in-situ observation system

Abstract

The invention relates to the field of seismic gas geochemical observation, in particular to a cross-fracture multi-layer Rn in-situ observation system, which comprises a plurality of Rn in-situ observation sensors respectively arranged at positions with different depths from the earth surface; a first through hole is formed in the well wall of the cross-fracture observation well, and the Rn in-situ observation sensor observes data of Rn gas entering the cross-fracture observation well through the first through hole. In-situ online sampling of the Rn gas is achieved through the multiple Rn in-situ observation sensors vertically distributed in the cross-fracture observation well, the Rn gas from different layers is actively diffused into the Rn in-situ observation sensors under driving of the activity of the Rn gas, and therefore in-situ observation of the Rn gas of the rocks at the different layers is achieved; therefore, the accuracy of judging the abnormal information of the underground Rn gas before the earthquake is improved, and the efficiency of Rn gas monitoring in earthquake short-term and temporary prediction is practically improved.

Description

Technical Field

[0001] The invention relates to the field of seismic gas geochemical observation, and in particular to a cross-fault multi-layer Rn in-situ observation system. Background Art

[0002] Earthquakes are the process of crustal medium destruction under the action of ground stress. Previous simulation experiments on gas release during rock destruction under stress have proved the objective fact of gas geochemical anomalies before earthquakes. Fault zones are both weak areas where earthquakes occur and the main channels for deep degassing in the earth. The few existing earthquake monitoring and prediction practices have detected relatively obvious gas geochemical precursor anomalies before earthquakes. Radon-222 ( 222 Rn, referred to as Rn, is an inert gas with a single source in the lithosphere (formed by the decay of radioactive elements in rock-forming minerals). It is a relatively common indicator of gas geochemical anomalies. It has also been one of the measurement items with relatively mature observation technology and higher earthquake prediction efficiency in the short-term earthquake prediction work.

[0003] Rn has a very short life span, with a half-life of 3.82 days, and a relatively large molecular diameter of 0.134 nanometers, which results in a short underground migration distance. Simulation experiments have found that in the absence of a preferred channel, the migration distance of Rn in intact rocks may be only at the meter level. However, my country's existing underground fluid observation stations are still mainly based on near-surface observations. For deep well observation sites, since the instruments are all arranged above the ground, the volume activity of Rn gas dissolved in water is still measured by sensors after the well water is diverted to the ground, degassing, gas collection, drying and filtering procedures; for freely dissipated fault soil gas and hot spring escape gas, a certain volume of gas is still collected by surface gas collection, and the volume activity of Rn gas is measured by surface sensors, which makes it difficult to accurately predict earthquake activity. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The object of the present invention is to provide a cross-fracture multi-layer Rn in-situ observation system that can improve the accuracy of the observed Rn gas data.

[0006] (II) Technical solution

[0007] In order to solve the above problems, the present invention provides a cross-fracture multi-layer Rn in-situ observation system, comprising: a cross-fracture observation well, a plurality of Rn in-situ observation sensors and a control host;

[0008] The cross-fault observation well is arranged in the underground soil layer;

[0009] The control host is arranged on the surface, and the Rn in-situ observation sensor is connected to the control host;

[0010] A plurality of the Rn in-situ observation sensors are respectively arranged at positions of different depths from the ground surface;

[0011] A plurality of groups of first through holes are arranged on the wall of the cross-fracture observation well, and the Rn in-situ observation sensor is arranged inside the cross-fracture observation well, and each of the Rn in-situ observation sensors corresponds to the position of a group of the first through holes;

[0012] The Rn in-situ observation sensor is used to observe data of the Rn gas that enters the cross-fracture observation well through the first through hole.

[0013] In another aspect of the present invention, preferably, the well wall of the cross-fracture observation well is provided with a groove penetrating to the bottom, the inner wall of the cross-fracture observation well is provided with a sleeve, and the sleeve wall is provided with multiple groups of second through holes, the spacing between two groups of first through holes is a first spacing, the spacing between two groups of second through holes is a second spacing, and the first spacing is different from the second spacing;

[0014] The outer wall of the sleeve is provided with a sleeve moving mechanism, and the control host includes a moving control module. The sleeve moving mechanism drives the sleeve to move along the length direction of the slot according to the instruction of the moving control module.

[0015] Another aspect of the present invention preferably further comprises a cable, and each of the Rn in-situ observation sensors is connected to the control host via the cable.

[0016] Another aspect of the present invention preferably further comprises a base, wherein the base is arranged at the wellhead of the cross-fracture observation well;

[0017] The base is provided with a positioning hole, and the cable is connected to the control host through the positioning hole.

[0018] In another aspect of the present invention, preferably,

[0019] An insulating filler is provided on the top of the cross-fault observation well;

[0020] The insulating filler is used to reduce the exchange of gas between surface air and the gas in the cross-fracture observation well.

[0021] In another aspect of the present invention, preferably, the outer wall of the cross-fault observation well is wrapped with at least one layer of sand-proof net, and the bottom of the cross-fault observation well is provided with multiple layers of sand-proof net.

[0022] In another aspect of the present invention, preferably, the buried depth of the cross-fault observation well is greater than the fracture depth at the drilling location.

[0023] In another aspect of the present invention, preferably, a plurality of the Rn in-situ observation sensors are respectively placed in different structural parts of the fault zone, and the structural parts include bedrock layers of the fault footwall, the fracture zone and the fault hanging wall.

[0024] In another aspect of the present invention, preferably, the spacing between two of the Rn in-situ observation sensors is greater than or equal to 10 meters.

[0025] In another aspect of the present invention, preferably, the control host includes a battery module, a solar power supply module, a sensor host module and a GPRS signal transmission module;

[0026] The solar power supply module, battery module, sensor host module and GPRS signal transmission module are connected in sequence;

[0027] The solar power supply module charges the battery module;

[0028] The battery module is connected to the Rn in-situ observation sensor to supply power to the Rn in-situ observation sensor;

[0029] The sensor host module is connected to the Rn in-situ observation sensor to collect observation data of the Rn in-situ observation sensor;

[0030] The GPRS signal transmission module is communicatively connected with a host computer, and the GPRS signal transmission module transmits the observation data to the host computer.

[0031] In another aspect of the present invention, preferably, the data of the Rn gas includes the volume activity of the Rn gas, and the Rn gas includes 222 Rn gas and 220 Rn gas;

[0032] The Rn in-situ observation sensor adopts diffusion type whole-point sampling;

[0033] The Rn in-situ observation sensor uses electrostatic spectroscopy to distinguish 222 Rn gas and 220 Volume activity of Rn gas.

[0034] (III) Beneficial effects

[0035] The above technical solution of the present invention has the following beneficial technical effects:

[0036] The present invention realizes in-situ online sampling of Rn gas through multiple Rn in-situ observation sensors vertically distributed in cross-fault observation wells. Driven by its own activity, Rn gas from different layers actively diffuses into the Rn in-situ observation sensors, thereby realizing in-situ observation of Rn gas in rocks of different layers, thereby improving the accuracy of identifying abnormal information of underground Rn gas before an earthquake, and effectively improving the effectiveness of Rn gas monitoring in short-term earthquake prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0038] Figure 2 is observation data of an embodiment of the present invention;

[0039] Reference numerals:

[0040] 1: Cross-fault observation well, 1-1: First through hole, 1-2: Sand prevention net,

[0041] 2: Rn in-situ observation sensor, 3: control host, 4: host computer, 5: cable, 6: base, 7: insulation filler. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0043] The accompanying drawings show schematic diagrams of structures according to embodiments of the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clarity. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0044] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0047] Embodiment 1

[0048] A cross-fracture multi-layer Rn in-situ observation system. Figure 1 FIG. 1 shows a schematic diagram of the overall structure of an embodiment of the present invention. Figure 1 As shown, including:

[0049] Cross-fracture observation well 1, multiple Rn in-situ observation sensors 2, control host 3 and host computer 4;

[0050] The cross-fault observation well 1 is set in the underground soil layer; the cross-fault observation well 1 is located on or near the geological fault zone to directly monitor the impact of the fault zone on the underground Rn gas data. In this embodiment, the depth and diameter of the cross-fault observation well 1 are not limited, and the depth and diameter of the cross-fault observation well 1 can be set according to the characteristics of the underground structure. The wall of the cross-fault observation well 1 is built with strong and corrosion-resistant materials to withstand the pressure of groundwater and the needs of long-term observation. In this embodiment, the wall of the cross-fault observation well 1 is made of PTFE polytetrafluoroethylene.

[0051] The buried depth of the cross-fault observation well 1 is not limited here. In this embodiment, the buried depth of the cross-fault observation well 1 is greater than the fracture depth at the drilling site. The buried depth of the cross-fault observation well 1 is greater than the depth of the fault zone, ensuring that the Rn in-situ observation sensor 2 in the well can capture the Rn gas data inside and around the fault zone.

[0052] The control host 3 is arranged on the surface of the earth, and the control host 3 is connected to the host computer 4 in communication; the host computer 4 receives the data from the control host 3 and performs in-depth analysis, including time series analysis, spatial distribution analysis, correlation analysis, etc., to obtain the relationship between the Rn gas data and the geological structure, groundwater activity, earthquake activity, etc. According to the preset threshold, the early warning mechanism can be automatically triggered to promptly notify relevant personnel to pay attention to possible abnormal situations, such as the abnormal increase of Rn gas data, which may be related to earthquake precursors.

[0053] A plurality of the Rn in-situ observation sensors 2 are respectively arranged at different depths from the surface; vertical layered monitoring is realized, and the arrangement depth of the Rn in-situ observation sensor 2 is based on the geological structure. The distribution of strata and lithology at different depths can be determined according to the geological exploration data, and a plurality of the Rn in-situ observation sensors 2 are arranged to ensure that the Rn gas data from different strata and different lithologies can be captured. In this embodiment, a plurality of the Rn in-situ observation sensors 2 are respectively arranged at different structural parts of the fault zone, and the structural parts include the bedrock layers of the fault footwall, the broken zone and the fault hanging plate. In the fault zone, the bedrock layers of the fault footwall, the broken zone and the fault hanging plate are the areas with the most intense geological activities and the most complex Rn gas data, so as to realize the accurate monitoring of Rn gas activities. Further, by comparing the sensor data of different structural parts such as the fault footwall, the broken zone and the fault hanging plate, the distribution differences and migration trends of Rn gas between different structural parts can be analyzed, which provides important basis for earthquake early warning, geological disaster assessment, etc. The number and position of the Rn in-situ observation sensors 2 can be flexibly adjusted. The number of Rn in-situ observation sensors 2 can be increased or decreased, or the layout of the Rn in-situ observation sensors 2 can be adjusted according to changes in research objectives and geological conditions to improve the accuracy and effectiveness of monitoring.

[0054] The well wall of the cross-fracture observation well 1 is provided with a plurality of groups of first through holes 1-1, and the specific number of each group of first through holes 1-1 is not limited here. The Rn in-situ observation sensor 2 is provided inside the cross-fracture observation well 1, and each of the Rn in-situ observation sensors 2 corresponds to the position of a group of the first through holes 1-1. Several first through holes 1-1 are provided in each group circumferentially of the well wall of the cross-fracture observation well 1, and each Rn in-situ observation sensor 2 includes a plurality of evenly distributed first through holes 1-1 near the well wall. The evenly distributed arrangement helps to reduce the problem of uneven distribution of Rn gas caused by the local effect of the well wall. At the same time, the circumferentially distributed first through holes can also enhance the mixing uniformity of the Rn gas in the well, so that the sensor can capture more representative Rn gas data. Each Rn in-situ observation sensor 2 includes a plurality of evenly distributed first through holes 1-1 near the sensor, and the Rn in-situ observation sensor 2 observes the data of the Rn gas entering the cross-fracture observation well 1 through the first through holes 1-1; the evenly distributed first through holes 1-1 ensure that the Rn in-situ observation sensor can fully contact the radon gas from different directions. The number and position of the first through holes can be adjusted according to the size, sensitivity and required monitoring range of the Rn in-situ observation sensor to achieve the best monitoring effect. In order to enhance the monitoring capability of a specific area, the number of first through holes can also be locally increased near the Rn in-situ observation sensor. Through the position and number of the first through holes 1-1, the Rn gas can flow more smoothly to the Rn in-situ observation sensor, thereby improving the data stability of the Rn in-situ observation sensor and reducing the monitoring error caused by poor airflow.

[0055] Furthermore, in this embodiment, the well wall of the cross-fracture observation well 1 is provided with a groove penetrating to the bottom, the inner wall of the cross-fracture observation well 1 is provided with a sleeve, and the wall of the sleeve is provided with multiple groups of second through holes, the spacing between two groups of first through holes 1-1 is the first spacing, the spacing between two groups of second through holes is the second spacing, and the first spacing is different from the second spacing; when a group of first through holes 1-1 and a group of second through holes are aligned, the Rn in-situ observation sensor 2 also corresponds to the positions of the two after alignment, and the Rn in-situ observation sensor 2 can collect data. The remaining groups of first through holes 1-1 and second through holes are in a sealed state because of the difference between the first spacing and the second spacing.

[0056] The outer wall of the sleeve is provided with a sleeve moving mechanism, and the control host 3 includes a moving control module. The sleeve moving mechanism drives the sleeve to move along the length direction of the slot according to the instruction of the moving control module. Furthermore, in the present embodiment, the slot is provided on the inner wall of the cross-fault observation well 1, and a stainless steel composite structure is adopted and filled with wear-resistant guide groove material. The slot depth is 20 mm and the width is 80 mm. A high-precision rack track is embedded. The sleeve moving mechanism is a servo-driven gear set that is provided on the outer wall of the sleeve and meshes with the rack. By providing a slot that penetrates to the bottom on the inner wall of the cross-fault observation well, and providing multiple groups of second through holes on the sleeve, combined with the sleeve moving mechanism, dynamic adjustment of the sensor observation position is realized. It breaks through the limitations of the traditional fixed observation mode, so that the Rn in-situ observation sensor can be flexibly moved according to actual needs to capture the changes in Rn concentration in different layers.

[0057] Furthermore, the sleeve is configured as a segmented closed structure, each segment of the closed structure has at least one group of second through holes, and the second through holes are provided with an aperture adjustment mechanism. In this embodiment, the aperture adjustment mechanism is configured as a petal-type opening and closing device, which is driven by a micro stepping motor and can dynamically adjust the diameter of the second through hole according to observation requirements, within a range of 0.5-5mm, thereby further optimizing the observation effect.

[0058] In this embodiment, the movement control method of the sleeve includes:

[0059] Construct a multi-source data fusion analysis model based on deep neural network to process the Rn concentration of each layer in real time;

[0060] When it is detected that the coefficient of variation of Rn concentration in a certain layer exceeds the threshold, the dynamic optimization algorithm is started;

[0061] Dynamic optimization algorithms include:

[0062] The optimal observation posture combination is calculated through the particle swarm algorithm to generate the sleeve residence time allocation matrix; then fuzzy PID control is used to achieve precise positioning of the sleeve, and high-density sampling is implemented in abnormal layers (the sampling frequency is increased to 10 Hz).

[0063] Furthermore, the system is equipped with a self-learning mechanism, which trains the LSTM prediction model through the historical earthquake precursor database to achieve predictive adjustment of the sleeve movement path, forming a three-level linkage control strategy of "abnormal triggering-dynamic focusing-predictive deployment".

[0064] The distance between the multiple Rn in-situ observation sensors 2 is not limited here. In this embodiment, the distance between each of the multiple Rn in-situ observation sensors 2 is greater than or equal to 10 meters.

[0065] The Rn in-situ observation sensor 2 is connected to the control host 3;

[0066] The control host 3 supplies power to the Rn in-situ observation sensor 2 and transmits the observation data of the Rn in-situ observation sensor 2 to the host computer 4. As the hub of the entire system, the control host 3 is responsible for providing a stable power supply for multiple Rn in-situ observation sensors 2. This ensures that the sensors can work continuously and stably without being affected by power fluctuations. Further, in this embodiment, the control host 3 includes a battery module, a solar power supply module, a sensor host module and a GPRS signal transmission module;

[0067] The solar power supply module, battery module, sensor host module and GPRS signal transmission module are connected in sequence;

[0068] The solar power supply module charges the battery module; the battery module is connected to the Rn in-situ observation sensor 2 to supply power to the Rn in-situ observation sensor 2; the battery module, as an energy storage unit of the control host 3, is responsible for storing the electric energy from the solar power supply module and providing a stable power supply for the Rn in-situ observation sensor 2. The solar power supply module uses the solar photovoltaic effect to convert light energy into electrical energy to charge the battery module. The green and sustainable energy utilization method not only reduces the operating cost of the system, but also conforms to the concept of environmental protection.

[0069] The sensor host module is connected to the Rn in-situ observation sensor 2 to collect the observation data of the Rn in-situ observation sensor; the sensor host module is responsible for communicating with the Rn in-situ observation sensor 2 to collect observation data in real time; the GPRS signal transmission module is connected to the host computer 4 for communication, and the GPRS signal transmission module transmits the observation data to the host computer 4. The GPRS signal transmission module uses the mobile communication network to realize wireless transmission of data. This transmission method has the advantages of wide coverage, fast transmission speed, high stability, etc., which ensures that the observation data can be transmitted to the host computer 4 in a timely and accurate manner for analysis and processing.

[0070] Furthermore, in this embodiment, a cable 5 is also included, and each of the Rn in-situ observation sensors 2 is connected to the control host 3 via the cable 5. Each Rn in-situ observation sensor 2 is physically connected to the control host 3 via the cable 5, ensuring that the data collected by the sensor can be stably and efficiently transmitted to the control host 3 for processing and storage. The cable 5 not only undertakes the task of data transmission, but also provides the necessary power support for the sensor. Taking into account the complex geological environment and climatic conditions that the cross-fault observation well 1 may face, the cable 5 is made of highly durable materials and has undergone corresponding corrosion-resistant treatment to ensure that it can operate stably and for a long time in harsh environments.

[0071] Furthermore, in this embodiment, a base 6 is further included, and the base 6 is arranged at the wellhead of the cross-fracture observation well 1; the base 6 is equivalent to a well cover, protecting the components in the well, and the base 6 is provided with a positioning hole, and the cable 5 is connected to the control host 3 through the positioning hole. The positioning hole provided on the base 6 not only provides a clear installation path for the cable 5, but also protects the cable 5 from external interference and damage.

[0072] Furthermore, in this embodiment, an insulating filler 7 is provided at the top of the cross-fracture observation well 1;

[0073] The insulating filler 7 is used to reduce the exchange of surface air with the gas in the cross-fault observation well 1, thereby reducing the influence of surface air mixing on the measurement effect of Rn gas in the cross-fault observation well 1.

[0074] Furthermore, in this embodiment, the outer wall of the cross-fault observation well 1 is wrapped with at least one layer of anti-sand net 1-2 to prevent bedrock sediment from entering the cross-fault observation well 1 through the well wall, and the bottom of the cross-fault observation well 1 is provided with multiple layers of anti-sand net 1-2 to prevent bedrock sediment from entering the cross-fault observation well 1 through the well bottom.

[0075] Further, in this embodiment, the data of the Rn gas includes the volume activity of the Rn gas, and the Rn gas includes 222 Rn gas and 220Rn gas; the Rn in-situ observation sensor 2 adopts diffusion-type whole-point sampling; the Rn in-situ observation sensor 2 uses electrostatic energy spectrum method to distinguish 222 Rn gas and 220 The volume activity of Rn gas can also meet the observation needs of Rn isotope ratios, so as to realize long-term continuous monitoring of Rn and its isotopes in different structural parts of the fault zone before and after the earthquake.

[0076] This embodiment realizes in-situ online sampling of Rn gas through multiple Rn in-situ observation sensors vertically distributed in cross-fault observation wells. Driven by its own activity, Rn gas from different layers actively diffuses into the Rn in-situ observation sensors, thereby realizing in-situ observation of Rn gas in rocks of different layers, thereby improving the accuracy of identifying abnormal underground Rn gas information before an earthquake, and effectively improving the effectiveness of Rn gas monitoring in short-term earthquake prediction.

[0077] In order to verify the stability of this embodiment, the Xianshuihe Fault Zone in Ganzi Tibetan Autonomous Prefecture, Sichuan Province, within the China Earthquake Science Experimental Field was selected as the experimental area through field surveys. Three cross-fault deep well Rn in-situ observation systems were built in different sections of the fault zone. Two Rn in-situ observation sensors were buried at different depths at each site. Figure 2 Observation data of an embodiment of the present invention is shown, such as Figure 2 As shown, it is the observation data of the Rn in-situ observation system of three deep wells across faults. After the construction of the Rn in-situ observation system of this embodiment is completed, the observation value is stable, and the trend change of the observation data of the two Rn in-situ observation sensors at different depths of the same observation station is basically consistent, and both are stable within a certain Rn volume activity range. Compared with the four Rn in-situ observation sensors at the other two test points, the Rn volume activity background value of the two Rn in-situ observation sensors at test point 3 is significantly higher; during the period when the observation data change trends of the two Rn in-situ observation sensors at the same test point are consistent, the Rn volume activity measured by the sensors with large burial depths at test points 1 and 2 is relatively high, indicating the practicality of the Rn in-situ observation system of this embodiment.

[0078] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

[0079] In the above description, the technical details of patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various means in the prior art can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above.

[0080] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, a person skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

[0081] Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

[0082] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A cross-fracture multi-layer Rn in-situ observation system, characterized in that: include: A cross-fracture observation well (1), a plurality of Rn in-situ observation sensors (2) and a control host (3); The cross-fault observation well (1) is arranged in an underground soil layer; The control host (3) is arranged on the ground surface, and the Rn in-situ observation sensor (2) is connected to the control host (3); The plurality of Rn in-situ observation sensors (2) are respectively arranged at positions of different depths from the ground surface; A plurality of groups of first through holes (1-1) are arranged on the well wall of the cross-fracture observation well (1), the Rn in-situ observation sensor (2) is arranged inside the cross-fracture observation well (1), and each of the Rn in-situ observation sensors (2) corresponds to the position of a group of the first through holes (1-1); The Rn in-situ observation sensor (2) is used to observe data of the Rn gas that enters the cross-fracture observation well (1) through the first through hole (1-1).

2. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The wall of the cross-fracture observation well (1) is provided with a groove penetrating to the bottom, the inner wall of the cross-fracture observation well (1) is provided with a sleeve, and the wall of the sleeve is provided with a plurality of groups of second through holes, the spacing between two groups of first through holes (1-1) is a first spacing, the spacing between two groups of second through holes is a second spacing, and the first spacing is different from the second spacing; The outer wall of the sleeve is provided with a sleeve moving mechanism, and the control host (3) comprises a moving control module. The sleeve moving mechanism drives the sleeve to move along the length direction of the slot according to the instruction of the moving control module.

3. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: It also includes a cable (5) and a base (6), and each of the Rn in-situ observation sensors (2) is connected to the control host (3) via the cable (5); The base (6) is arranged at the wellhead of the cross-fracture observation well (1); The base (6) is provided with a positioning hole, and the cable (5) is connected to the control host (3) through the positioning hole.

4. The cross-fracture multi-layer Rn in-situ observation system according to claim 3 is characterized in that: An insulating filler (7) is provided at the top of the cross-fracture observation well (1); The insulating filler (7) is used to reduce the exchange of gas between surface air and the gas in the cross-fracture observation well (1).

5. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The outer wall of the cross-fault observation well (1) is wrapped with at least one layer of sand-proof net (1-2), and the bottom of the cross-fault observation well (1) is provided with multiple layers of sand-proof net (1-2).

6. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The buried depth of the cross-fault observation well (1) is greater than the fault depth at the drilling location.

7. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: A plurality of the Rn in-situ observation sensors (2) are respectively arranged at different structural locations of the fault zone, wherein the structural locations include the bedrock layer of the fault footwall, the fracture zone and the fault hanging wall.

8. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The distance between any two of the Rn in-situ observation sensors (2) is greater than or equal to 10 meters.

9. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The control host (3) comprises a battery module, a solar power supply module, a sensor host module and a GPRS signal transmission module; The solar power supply module, battery module, sensor host module and GPRS signal transmission module are connected in sequence; The solar power supply module charges the battery module; The battery module is connected to the Rn in-situ observation sensor (2) to supply power to the Rn in-situ observation sensor (2); The sensor host module is connected to the Rn in-situ observation sensor (2) to collect observation data of the Rn in-situ observation sensor; The GPRS signal transmission module is in communication connection with a host computer (4), and the GPRS signal transmission module transmits the observation data to the host computer (4).

10. The cross-fracture multi-layer Rn in-situ observation system according to claim 1 is characterized in that: The data of the Rn gas includes the volume activity of the Rn gas, and the Rn gas includes 222 Rn gas and 220 Rn gas; The Rn in-situ observation sensor (2) adopts diffusion type whole-point sampling; The Rn in-situ observation sensor (2) uses electrostatic energy spectrum method to distinguish 222 Rn gas and 220 Volume activity of Rn gas.

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