UAV-based airborne or semi-airborne geophysical and geochemical CO2 monitoring systems and methods

Abstract

This invention discloses an airborne or semi-airborne geophysical and geochemical CO2 monitoring system and method based on unmanned aerial vehicles (UAVs). The UAV is equipped with a carbon dioxide gas sensor, an airborne three-component electromagnetic field sensor, and an airborne horizontally controllable electromagnetic field transmitting coil mounted at its lowest point. Inside the UAV are a fiber optic CO2 modulation and demodulation instrument, a controllable electromagnetic source transmitter, and a three-component electromagnetic field data acquisition instrument. It also includes an electromagnetic field transmitting coil or a rectangular current source transmitting antenna laid around the ground CO2 injection well, and a controllable current transmitting source. By processing the CO2 concentration in the air at different elevations and real-time or time-shifted airborne or semi-airborne three-dimensional controllable source electromagnetic data collected at different stages, long-term safety monitoring of the migration of supercritical CO2 underground is achieved. This prevents supercritical CO2 from leaking to the ground along the well walls of the injection or monitoring wells or through shallow surface faults or fissures activated by high-pressure supercritical CO2 injected underground, thus preventing geological disasters.

Description

Technical Field

[0001] This invention relates to the fields of underground geochemical and electromagnetic exploration technology, and more specifically, to an airborne or semi-airborne geochemical CO2 monitoring system and method based on unmanned aerial vehicles (UAVs). Background Technology

[0002] CCS, or Carbon Capture and Storage, is a technology used to mitigate climate change and reduce carbon dioxide emissions. Its origins lie in the technology of using carbon dioxide to enhance oil recovery, which emerged in the United States in the 1970s. The three key elements of CCS are the capture, transport, and geological storage of carbon dioxide. CCUS, or Carbon Capture, Utilization, and Storage, is a concept proposed by my country based on its own circumstances, adding the carbon dioxide utilization stage to CCS. The definition of CCS and CCUS: Carbon Capture and Storage (CCS) technology refers to the process of separating carbon dioxide from industrial or related emission sources, transporting it to storage sites, and isolating it from the atmosphere for a long period. This technology is considered the most economical and feasible way to reduce greenhouse gas emissions and mitigate global warming on a large scale in the future. CCUS stands for Carbon Capture, Utilization and Storage. It refers to carbon capture, storage and reuse technologies. Carbon dioxide (CO2) capture, utilization and storage (CCUS) refers to the process of separating CO2 from industrial processes, energy use or the atmosphere and using it directly or injecting it into the ground to achieve permanent CO2 emission reduction. As one of the key technologies to address global climate change, CCUS aims to capture CO2 at its source, purify it and then recycle it, or store it underground, thereby balancing the negative impact of CO2 on the climate.

[0003] Carbon capture, utilization, and storage (CCUS) technology represents a new trend in CCS technology. It involves capturing and purifying carbon dioxide emitted during production processes, then recycling or storing it in new production processes. This technology offers synergistic benefits for large-scale greenhouse gas emission reduction and low-carbon utilization of fossil fuels, making it a crucial technological option for addressing global warming. CCS technology primarily consists of four stages: capture, transport, geological storage and monitoring, and enhancement of oil recovery rate (EOR / EGR). The fourth stage is optional and has potential benefits.

[0004] Through numerous CCS and CCUS projects, millions, tens of millions, or even hundreds of millions of tons of high-pressure supercritical carbon dioxide have been injected underground. Because carbon dioxide has a higher oxygen content, if this injected carbon dioxide leaks to the surface through the walls of injection or monitoring wells, or through shallow faults or fractures activated by the high-pressure underground carbon dioxide, it will cause massive geological disasters and incalculable loss of life and property in the leaking areas. Therefore, we need to deploy real-time, long-term, and effective monitoring systems both on the surface and underground in CCS and CCUS projects to monitor the leakage of underground carbon dioxide to the surface in real time. Once a carbon dioxide leak occurs at the surface, we must promptly issue early warning information, activate emergency response mechanisms, take necessary engineering and technical measures to block the carbon dioxide leakage channels, evacuate people in and near the leakage area, and minimize the occurrence of major geological disasters.

[0005] Currently, carbon dioxide gas monitoring sensors are installed on the surface and at the wellhead in CCS and CCUS work areas for real-time monitoring and early warning. However, this method is only passive monitoring and cannot predict or monitor the migration status of high-pressure carbon dioxide underground when there is no carbon dioxide leakage on the surface or downhole. Another method uses surface three-dimensional time-lapse seismic (four-dimensional seismic) or time-lapse three-dimensional vertical seismic profile (4D-VSP) exploration technology to monitor the migration of carbon dioxide in deep underground reservoirs. Since the density of supercritical carbon dioxide reaches 0.7, the density difference with pore water in deep underground formations is not significant. Therefore, after supercritical carbon dioxide displaces pore water in underground reservoirs, the elastic parameters within the deep underground reservoirs change little, and the data collected by surface three-dimensional time-lapse seismic (four-dimensional seismic) or time-lapse three-dimensional vertical seismic profile (4D-VSP) also show little change. Considering the acquisition errors of surface or well time-lapse seismic data and errors in the data processing process, the reliability of time-lapse seismic data processing results decreases significantly. Therefore, surface or downhole time-lapse seismic data is difficult to accurately monitor the migration and occurrence status of carbon dioxide fronts in deep underground reservoirs. Summary of the Invention

[0006] The purpose of this invention is to provide a CO2 monitoring system and method based on UAV-based integrated airborne or semi-airborne geophysical and geochemical exploration. By processing the CO2 concentration data collected at different stages in real time or time-shifted at the same elevation in the air and the three-component electromagnetic field data of the airborne or semi-airborne controllable source, the efficiency of high-pressure supercritical CO2 injection into underground reservoirs can be evaluated in real time. The system also provides real-time and long-term safety monitoring of the migration of underground high-pressure supercritical CO2, preventing supercritical carbon dioxide from leaking to the surface along the well walls of the injection well or monitoring well, or through shallow surface faults or fractures activated by the injected high-pressure supercritical CO2.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0008] Firstly, the CO2 monitoring system based on UAV for airborne or semi-airborne integrated geophysical and geochemical exploration provided in this application includes a UAV, a carbon dioxide gas sensor mounted at the bottom of the UAV, an airborne three-component electromagnetic field sensor mounted above the carbon dioxide gas sensor, an airborne horizontally controllable electromagnetic field transmitting coil mounted above the airborne three-component electromagnetic field sensor, and an optical fiber CO2 modulation and demodulation instrument, a controllable electromagnetic source transmitter, and a three-component electromagnetic field data acquisition instrument installed inside the UAV. It also includes a large-diameter, high-power electromagnetic field transmitting coil or a long-length, high-power rectangular current source transmitting antenna laid around the ground high-pressure supercritical CO2 injection well, and a ground high-power controllable current transmitting source.

[0009] The carbon dioxide gas sensor can be a chemical CO2 sensor or a fiber optic CO2 sensor;

[0010] The airborne three-component electromagnetic field sensor is a three-component magnetic field and three-component electric field sensor composed of three mutually orthogonal magnetic field sensors and a six-sided cubic electrode plate.

[0011] The three mutually orthogonal magnetic field sensors can be fluxgate magnetic field sensors, induction coil magnetic field sensors, or fiber optic magnetic field sensors.

[0012] The three-component electric field sensor is composed of six-sided cubic electrode plates. Each pair of parallel electrode plates of the six-sided cubic electrode plates is a capacitive electric field sensor in this direction.

[0013] The aforementioned horizontally controllable electromagnetic field transmitting coil consists of three mutually orthogonal electromagnetic field transmitting coils mounted directly below the UAV, with diameters ranging from 1 to 5 meters.

[0014] The diameter of the large-diameter, high-power electromagnetic field transmitting coils laid around the CO2 injection wells on the ground is between 1 and 5 kilometers, and the transmitting coils are connected to a high-power, controllable current transmitting source on the ground.

[0015] The long, high-power rectangular current source transmitting antenna laid around the CO2 injection well on the ground has a side length between 1 km and 5 km. A ground-based high-power controllable current transmitting source is connected in the middle of each side, and there are grounded copper power supply electrode rods at both ends of each side.

[0016] The UAV is equipped with an operation control computer system. Before the construction operation, the coordinates of the UAV's flight survey line, the trajectory elevation, the trajectory spacing, the flight speed and other control information are input.

[0017] The UAV is equipped with a data acquisition and control computer system, which is connected to an optical fiber CO2 modulator / demodulator, a controllable electromagnetic source transmitter, a three-component electromagnetic field data acquisition instrument, and a remote sensing device.

[0018] The carbon dioxide gas sensor mounted at the bottom of the UAV is connected to the onboard fiber optic CO2 modulation and demodulation instrument via an optical fiber composite cable.

[0019] The airborne three-component electromagnetic field sensor mounted below the UAV is connected to the onboard data acquisition and control computer system via a cable.

[0020] The airborne horizontal controllable electromagnetic field transmitting coil mounted below the UAV is connected to the airborne controllable electromagnetic source transmitter via a cable.

[0021] The monitoring method of UAV-based aerial or semi-aerial geophysical and geochemical CO2 monitoring system includes the following specific steps:

[0022] (1) Before injecting high-pressure supercritical CO2 into the ground, conduct aerial or semi-aerial geophysical and geochemical baseline data measurements based on UAVs in the monitoring and construction operation area around the high-pressure supercritical CO2 injection well on the ground, and establish a baseline model of surface CO2 concentration distribution data and a baseline model of resistivity distribution in three-dimensional space in underground rock strata.

[0023] (2) Before construction operations, perform a self-check on all flight control functions of the UAV system itself;

[0024] (3) Then perform self-tests on all airborne data acquisition and control computer systems, fiber optic CO2 modulation and demodulation instruments, controllable electromagnetic source transmitters, and three-component electromagnetic field data acquisition instruments.

[0025] (4) Then, self-testing is performed on the carbon dioxide gas sensor, the airborne three-component electromagnetic field sensor and the airborne horizontal controllable electromagnetic field transmitting coil that are mounted on the UAV.

[0026] (5) Input the control information such as flight survey line coordinates, flight track elevation, flight track spacing, and flight speed required for monitoring the construction work area into the UAV;

[0027] (6) When the UAV flies to the pre-set survey line position in the monitoring construction work area, the airborne data acquisition and control computer system, fiber optic CO2 modulation and demodulation instrument, controllable electromagnetic source transmitter, three-component electromagnetic field data acquisition instrument, carbon dioxide gas sensor, airborne three-component electromagnetic field sensor and airborne horizontal controllable electromagnetic field transmitting coil are activated.

[0028] (7) Various sensors mounted under the UAV collect high-pressure supercritical CO2 concentration data along the survey line in the monitoring and construction work area around the ground high-pressure supercritical CO2 injection well according to the pre-designed parameters such as flight survey line coordinates, flight line elevation, flight line spacing, and flight speed. At the same time, they collect airborne three-component electromagnetic field data excited by the airborne horizontal controllable electromagnetic field transmitting coil.

[0029] (8) After the monitoring of the airborne high-pressure supercritical CO2 concentration data and the airborne three-component electromagnetic field data in the construction work area are completed, the airborne controllable electromagnetic source transmitter is turned off, and the ground high-power controllable current source is started to transmit alternating current to the ground large-diameter high-power electromagnetic field transmitting coil or long-length high-power rectangular current source transmitting antenna.

[0030] (9) The various sensors mounted on the UAV once again collect high-pressure supercritical CO2 concentration data along the survey line in the monitoring and construction work area around the ground high-pressure supercritical CO2 injection well according to the pre-designed parameters such as flight survey line coordinates, flight line elevation, flight line spacing, and flight speed. At the same time, they collect semi-airborne three-component electromagnetic field data excited underground by the ground large-diameter high-power electromagnetic field transmitting coil or long-length high-power rectangular current source transmitting antenna.

[0031] (10) Perform data preprocessing such as elevation correction and velocity correction of CO2 sensor on the CO2 concentration data collected in the monitoring and construction operation area around the ground high-pressure supercritical CO2 injection well for two consecutive times, and then perform linear or nonlinear two-dimensional interpolation processing to finally generate a CO2 concentration distribution map of the air at the same elevation from the ground within the monitoring and construction operation area around the ground high-pressure supercritical CO2 injection well.

[0032] (11) Perform data preprocessing such as elevation correction, velocity correction and noise reduction on the airborne three-component electromagnetic field data collected in step (7), and then perform inversion processing of the three-dimensional airborne three-component electromagnetic field data to obtain the distribution of resistivity anomalies in the shallow strata below the ground surface in three-dimensional space.

[0033] (12) Perform data preprocessing such as elevation correction, velocity correction and noise reduction on the semi-airborne three-component electromagnetic field data collected in step (9), and then perform inversion processing on the semi-airborne three-dimensional three-component electromagnetic field data to obtain the distribution of resistivity in the deeper strata below the ground surface in three-dimensional space.

[0034] (13) Perform data fusion processing on the resistivity data in the shallow and deep underground strata obtained in steps (11) and (12) to establish the accurate distribution of resistivity in the shallow and deep underground strata in three-dimensional space.

[0035] (14) After injecting high-pressure supercritical CO2 into the ground, repeat steps (2) to (13) periodically to obtain the CO2 concentration distribution map in the air at the same elevation above the ground within the monitoring construction area after injecting high-pressure supercritical CO2 into the ground and the resistivity distribution in the deeper strata below the ground surface in three-dimensional space.

[0036] (15) Perform differential processing on the CO2 concentration distribution data in the air at the same elevation above the ground obtained in step (14) after each injection of high-pressure supercritical CO2 into the ground and the CO2 concentration distribution data in the air at the same elevation above the ground measured in step (10) when no high-pressure supercritical CO2 was injected into the ground.

[0037] (16) The resistivity distribution data in three-dimensional space of the shallow and deeper strata below the ground surface obtained in step (13) after each injection of high-pressure supercritical CO2 into the ground is differentially processed with the resistivity distribution data in three-dimensional space of the shallow and deeper strata when no high-pressure supercritical CO2 is injected into the ground.

[0038] (17) Analyze and study the differential concentration data of high-pressure supercritical CO2 obtained in step (15). When the differential data of CO2 concentration distribution in the air at the ground elevation is abnormal, it indicates that the high-pressure supercritical CO2 injected into the well may have a risk of migration and leakage to the ground.

[0039] (18) Analyze and study the resistivity difference data in the shallow and deep underground strata obtained in step (16). When anomalies in the resistivity distribution difference data in the shallow and deep underground strata appear, it indicates that the high-pressure supercritical CO2 injected into the well may have a risk of migration and leakage to the surface.

[0040] (19) When the differential data anomaly areas appearing in steps (17) and (18) are basically coincident on the surface, it can be basically determined that the high-pressure supercritical CO2 injected into the well may have migrated and leaked to the surface. It is necessary to immediately send an early warning message to the high-pressure supercritical CO2 injector that the high-pressure supercritical CO2 may have migrated and leaked to the surface. It is necessary to pay attention to this immediately and take corresponding technical measures and safety precautions.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] In this invention, unmanned aerial vehicles (UAVs) are used to conduct rapid airborne or semi-airborne geophysical and geochemical surveys and controlled-source electromagnetic surveys in the monitoring area around wells where high-pressure supercritical CO2 is injected underground. This allows for real-time measurement or monitoring of the changes in airborne CO2 concentration distribution at ground level before and after the injection of high-pressure supercritical CO2 into the underground well, as well as the changes in resistivity distribution in the reservoir over time. The migration and storage status of the supercritical CO2 front in the underground reservoir are monitored and determined. Furthermore, the processing results of real-time or airborne or semi-airborne time-shifted controlled-source electromagnetic data collected at different stages are used to evaluate the efficiency of ultra-high-pressure supercritical CO2 injection into the underground reservoir in real time, and to conduct long-term safety monitoring of the migration of underground high-pressure supercritical CO2, preventing leakage of high-pressure supercritical CO2 to the surface along the well walls of the injection or monitoring well or through shallow surface faults or fractures activated by the injected high-pressure supercritical CO2. Attached Figure Description

[0043] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0044] Figure 1 This is a schematic diagram of the structure of an aerial or semi-aerial geophysical and geochemical CO2 monitoring system based on an unmanned aerial vehicle (UAV) in an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of the construction site layout of the UAV-based aerial or semi-aerial geophysical and geochemical CO2 monitoring system in an embodiment of the present invention.

[0046] The attached diagram shows the markings and corresponding component names:

[0047] 1. Unmanned Aerial Vehicle (UAV); 2. Carbon Dioxide Gas Sensor; 3. Aerial Three-Component Electromagnetic Field Sensor; 4. Aerial Horizontal Controllable Electromagnetic Field Transmitting Coil; 5. Fiber Optic CO2 Modulation and Demodulation Instrument; 6. Controllable Electromagnetic Source Transmitter; 7. Three-Component Electromagnetic Field Data Acquisition Instrument; 8. Large-Diameter High-Power Electromagnetic Field Transmitting Coil; 9. Long-Length High-Power Rectangular Current Source Transmitting Antenna; 10. Ground High-Power Controllable Current Transmitting Source; 11. Copper Power Supply Electrode Rod; 12. High-Current Power Supply Wire; 13. Data Acquisition and Control Computer System; 31. Magnetic Field Sensor; 32. Six-Sided Cubic Electrode Plate. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0051] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0052] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0053] In the description of the embodiments of the present invention, "multiple" means at least two.

[0054] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0055] Example 1:

[0056] like Figure 1 and Figure 2As shown, this embodiment provides an airborne or semi-airborne geophysical CO2 monitoring system based on an unmanned aerial vehicle (UAV), including a UAV 1, a carbon dioxide gas sensor 2 mounted at the bottom of the UAV 1, an airborne three-component electromagnetic field sensor 3 mounted above the carbon dioxide gas sensor 2, an airborne horizontally controllable electromagnetic field transmitting coil 4 mounted above the airborne three-component electromagnetic field sensor 3, an optical fiber CO2 modulation and demodulation instrument 5, a controllable electromagnetic source transmitter 6, and a three-component electromagnetic field data acquisition instrument 7 carried inside the UAV, and also includes a large-diameter, high-power electromagnetic field transmitting coil 8 or a long-length, high-power rectangular current source transmitting antenna 9 laid around the ground high-pressure supercritical CO2 injection well, and a ground-based high-power controllable current transmitting source 10 (…). Figure 2 );

[0057] The carbon dioxide gas sensor 2 can be a chemical CO2 sensor or a fiber optic CO2 sensor;

[0058] The airborne three-component electromagnetic field sensor 3 is a three-component magnetic field and three-component electric field sensor composed of three mutually orthogonal magnetic field sensors 31 and a hexagonal cubic electrode plate 32. Figure 1 );

[0059] The three mutually orthogonal magnetic field sensors 31 can be fluxgate magnetic field sensors, induction coil magnetic field sensors, or fiber optic magnetic field sensors.

[0060] The three-component electric field sensor is composed of a six-sided cubic electrode plate 32, and each pair of parallel electrode plates of the six-sided cubic electrode plate 32 is a capacitive electric field sensor in this direction. Figure 1 );

[0061] The airborne horizontally controllable electromagnetic field transmitting coil 4 consists of three mutually orthogonal electromagnetic field transmitting coils mounted directly below the UAV, with a diameter between 1 meter and 5 meters.

[0062] like Figure 2 As shown, the diameter of the large-diameter, high-power electromagnetic field transmitting coil 8 laid around the CO2 injection well on the ground is between 1 km and 5 km. The transmitting coil 8 is connected to the ground high-power controllable current transmitting source 10.

[0063] The long, high-power rectangular current source transmitting antenna 9, which is laid around the CO2 injection well on the ground, has a side length between 1 km and 5 km. A ground-based high-power controllable current transmitting source 10 is connected in the middle of each side, and there are grounded copper power supply electrode rods 11 at both ends of each side.

[0064] The UAV 1 is equipped with a data acquisition and control computer system 13. Before the construction operation, the flight survey line coordinates, flight path elevation, flight path spacing, flight speed and other control information of the UAV 1 are input.

[0065] The UAV 1 is equipped with a data acquisition and control computer system 13, which is connected to the fiber optic CO2 modulator / demodulator 5, the controllable electromagnetic source transmitter 6, and the three-component electromagnetic field data acquisition instrument 7.

[0066] The carbon dioxide gas sensor 2, mounted at the bottom of the UAV 1, is connected to the onboard fiber optic CO2 modulation and demodulation instrument 5 via an optoelectronic composite cable.

[0067] The airborne three-component electromagnetic field sensor 3, mounted below the UAV 1, is connected to the airborne data acquisition and control computer system 13 via a cable;

[0068] The airborne horizontal controllable electromagnetic field transmitting coil 4, mounted below the UAV 1, is connected to the airborne controllable electromagnetic source transmitter 6 via a cable.

[0069] The monitoring method of UAV-based aerial or semi-aerial geophysical and geochemical CO2 monitoring system includes the following specific steps:

[0070] (a) Before injecting high-pressure supercritical CO2 into the ground, conduct aerial or semi-aerial geophysical and geochemical baseline data measurements based on UAVs in the monitoring and construction operation area around the high-pressure supercritical CO2 injection well on the ground to establish a baseline model of surface CO2 concentration distribution data and a baseline model of resistivity distribution in underground rock strata in three-dimensional space.

[0071] (b) Before construction operations, perform a self-check on all flight control functions of the UAV 1 system itself;

[0072] (c) Then perform self-tests on all airborne data acquisition and control computer systems 13, fiber optic CO2 modulator / demodulator 5, controllable electromagnetic source transmitter 6, and three-component electromagnetic field data acquisition instrument 7.

[0073] (d) Then, self-tests were performed on the carbon dioxide gas sensor 2, the airborne three-component electromagnetic field sensor 3, and the airborne horizontal controllable electromagnetic field transmitting coil 4 mounted on the UAV 1.

[0074] (e) Input the control information required for monitoring the construction work area, such as flight line coordinates, flight line elevation, flight line spacing, and flight speed, into the UAV1;

[0075] (f) When the UAV 1 flies to the pre-set survey line position in the monitoring construction work area, the airborne data acquisition and control computer system 13, fiber optic CO2 modulation and demodulation instrument 5, controllable electromagnetic source transmitter 6, three-component electromagnetic field data acquisition instrument 7, carbon dioxide gas sensor 2, airborne three-component electromagnetic field sensor 3 and airborne horizontal controllable electromagnetic field transmitting coil 4 are activated.

[0076] (g) Various sensors mounted below the UAV 1 collect high-pressure supercritical CO2 concentration data along the survey line in the monitoring and construction work area around the ground high-pressure supercritical CO2 injection well according to the pre-designed parameters such as flight survey line coordinates, flight line elevation, flight line spacing, and flight speed. At the same time, they collect airborne three-component electromagnetic field data excited by the airborne horizontal controllable electromagnetic field transmitting coil 4.

[0077] (h) After the monitoring of the airborne high-pressure supercritical CO2 concentration data and airborne three-component electromagnetic field data in the construction work area is completed, the airborne controllable electromagnetic source transmitter 6 is turned off, and the ground high-power controllable current transmitter 10 is started to transmit alternating current to the ground large-diameter high-power electromagnetic field transmitting coil 8 or the long-length high-power rectangular current source transmitting antenna 9.

[0078] (i) Various sensors mounted below the UAV 1 collect high-pressure supercritical CO2 concentration data along the survey line in the monitoring and construction work area around the ground high-pressure supercritical CO2 injection well according to the pre-designed parameters such as flight survey line coordinates, flight line elevation, flight line spacing, and flight speed. Simultaneously, they collect semi-airborne three-component electromagnetic field data excited underground by the ground large-diameter high-power electromagnetic field transmitting coil 8 or the long-length high-power rectangular current source transmitting antenna 9.

[0079] (j) Perform data preprocessing such as elevation correction and velocity correction on the CO2 concentration data in the air collected in the monitoring and construction operation area around the ground high-pressure supercritical CO2 injection well for two consecutive times. Then perform linear or nonlinear two-dimensional interpolation processing to finally generate a CO2 concentration distribution map in the air at the same elevation as the ground within the monitoring and construction operation area around the ground high-pressure supercritical CO2 injection well.

[0080] (k) Perform data preprocessing such as elevation correction, velocity correction and noise reduction on the airborne three-component electromagnetic field data collected in step (g), and then perform inversion processing of the three-dimensional airborne three-component electromagnetic field data to obtain the distribution of resistivity anomalies in the shallow strata below the ground surface in three-dimensional space.

[0081] (l) Perform data preprocessing such as elevation correction, velocity correction and noise reduction on the semi-airborne three-component electromagnetic field data collected in step (i), and then perform inversion processing on the semi-airborne three-dimensional three-component electromagnetic field data to obtain the distribution of resistivity in the deeper strata below the ground surface in three-dimensional space.

[0082] (m) Perform data fusion processing on the resistivity data in the shallow and deep underground strata obtained in steps (k) and (l) to establish the accurate distribution of resistivity in the shallow and deep underground strata in three-dimensional space.

[0083] (n) After injecting high-pressure supercritical CO2 into the ground, repeat steps (b) to (m) periodically to obtain the CO2 concentration distribution map in the air at the same elevation above the ground within the monitoring construction area after injecting high-pressure supercritical CO2 into the ground, and the resistivity distribution in the deeper strata below the ground surface in three-dimensional space.

[0084] (o) Perform differential processing on the CO2 concentration distribution data in the air at the same elevation above the ground obtained in step (n) after each injection of high-pressure supercritical CO2 into the ground and the CO2 concentration distribution data in the air at the same elevation above the ground measured in step (j) when no high-pressure supercritical CO2 was injected into the ground.

[0085] (p) The resistivity distribution data in three-dimensional space of the shallow and deeper strata below the ground surface obtained in step (m) after each injection of high-pressure supercritical CO2 into the ground is differentially processed with the resistivity distribution data in three-dimensional space of the shallow and deeper strata when no high-pressure supercritical CO2 is injected into the ground.

[0086] (q) Analyze and study the differential concentration data of high-pressure supercritical CO2 obtained in steps (o) and (p). When there is an anomaly in the differential data of CO2 concentration distribution in the air at the same elevation as the ground, it indicates that the high-pressure supercritical CO2 injected into the well may have a risk of migration and leakage to the ground.

[0087] (r) The resistivity difference data in the shallow and deep underground strata obtained in steps (o) and (p) are analyzed and studied. When anomalies in the resistivity distribution difference data in the shallow and deep underground strata appear, it indicates that the high-pressure supercritical CO2 injected into the well may have a risk of migration and leakage to the surface.

[0088] (s) When the projections of the differential data anomalies appearing in steps (q) and (r) on the surface essentially overlap, the saturation state and frontal migration change state of the high-pressure supercritical CO2 injected into the well in the three-dimensional space of the underground reservoir can be judged separately, and the saturation state judgment results and frontal migration judgment results can be obtained respectively. This enables real-time monitoring of the high-pressure supercritical CO2 injected into the underground reservoir, preventing geological disasters caused by underground CO2 leakage to the surface. At this point, it can be basically determined that high-pressure supercritical CO2 has migrated and leaked to the surface. It is necessary to immediately issue an early warning message to the high-pressure supercritical CO2 injector, urging the construction party to conduct timely on-site investigation and surface CO2 concentration testing and monitoring, and to adopt corresponding technical countermeasures and safety precautions to prevent geological disasters caused by CO2 leakage to the surface.

[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A UAV-based airborne or semi-airborne geophysical CO2 monitoring system, characterized in that, The unmanned aerial vehicle (1) is provided with a carbon dioxide gas sensor (2) mounted at the lowermost part of the unmanned aerial vehicle (1), an air three-component electromagnetic field sensor (3) mounted above the carbon dioxide gas sensor (2), and an air horizontal controllable electromagnetic field transmitting coil (4) mounted above the air three-component electromagnetic field sensor (3), and the unmanned aerial vehicle (1) is internally provided with a fiber CO2 modulation and demodulation instrument (5), a controllable electromagnetic source transmitter (6), and a three-component electromagnetic field data acquisition instrument (7), and further comprises a large-diameter and high-power electromagnetic field transmitting coil (8) or a large-length and high-power rectangular current source transmitting antenna (9) laid around a ground high-pressure supercritical CO2 injection well, and a ground high-power controllable current transmitting source (10). The carbon dioxide gas sensor (2) is a fiber CO2 sensor or a chemical CO2 sensor. The air three-component electromagnetic field sensor (3) is a three-component magnetic field sensor composed of three mutually orthogonal magnetic field sensors (31) and a three-component electric field sensor composed of a six-surface cube electrode plate (32). The three mutually orthogonal magnetic field sensors (31) are magnetic flux gate magnetic field sensors, induction coil type induction magnetic field sensors, optical pump magnetic field sensors, superconducting magnetic field sensors, or fiber magnetic field sensors. The three-component electric field sensor is composed of a six-surface cube electrode plate (32), and every two parallel electrode plates of the six-surface cube electrode plate (32) are a capacitive electric field sensor in a direction. The air horizontal controllable electromagnetic field transmitting coil (4) is a horizontal controllable electromagnetic field transmitting coil mounted directly below the unmanned aerial vehicle, and the diameter is between 1 meter and 5 meters.

2. The UAV-based airborne or semi airborne geochemical CO2 monitoring system according to claim 1, wherein, The large-diameter and high-power electromagnetic field transmitting coil (8) laid on the ground has a diameter of between 1 kilometer and 5 kilometers, and is connected with the ground high-power controllable current transmitting source (10). 3.The UAV-based airborne or semi-airborne geochemical CO2 monitoring system according to claim 1, wherein, The large-length and high-power rectangular current source transmitting antenna (9) laid on the ground has a length of between 1 kilometer and 5 kilometers, and a ground high-power controllable current transmitting source (10) is connected in the middle of each length of large-current power supply wire (12), and each length of large-current power supply wire (12) has copper power supply electrode rods (11) grounded at both ends.

4. The UAV-based airborne or semi airborne geochemical CO2 monitoring system according to claim 1, wherein, The unmanned aerial vehicle (1) is internally provided with a data acquisition control computer system (13), and flight survey line track coordinates, track elevation, track spacing, and flight speed control information are input into the unmanned aerial vehicle (1) before construction operation.

5. The UAV-based airborne or semi airborne geochemical CO2 monitoring system according to claim 4, wherein, The data acquisition control computer system (13) is connected with the fiber CO2 modulation and demodulation instrument (5), the controllable electromagnetic source transmitter (6), and the three-component electromagnetic field data acquisition instrument (7).

6. The UAV-based airborne or semi airborne geochemical CO2 monitoring system according to claim 1, wherein, The fiber or chemical carbon dioxide gas sensor (2) mounted at the lowermost part of the unmanned aerial vehicle (1) is connected with the fiber CO2 modulation and demodulation instrument (5) on the unmanned aerial vehicle (1) through an optical-electric composite cable.

7. The UAV-based airborne or semi airborne geochemical CO2 monitoring system according to claim 1, wherein, The air three-component electromagnetic field sensor (3) mounted below the unmanned aerial vehicle (1) is connected with the data acquisition control computer system (13) through the photoelectric composite cable. 8.The UAV-based airborne or semi-airborne geochemical CO2 monitoring system according to claim 1, wherein, The air horizontal controllable electromagnetic field transmitting coil (4) mounted below the unmanned aerial vehicle (1) is connected with the controllable electromagnetic source transmitter (6) through the photoelectric composite cable.

9. The method for monitoring CO2 by aerial or semi-aerial geochemical exploration based on UAVs, applied to the system for monitoring CO2 by aerial or semi-aerial geochemical exploration based on UAVs according to any one of claims 1-8, characterized in that, The method comprises the following specific steps: (a) Before injecting high-pressure supercritical CO2 into the ground, first conduct unmanned aerial vehicle-based aerial or semi-aerial geophysical prospecting reference data measurement in the monitoring construction operation area around the high-pressure supercritical CO2 injection well, and establish a baseline model of the ground CO2 concentration distribution data and a baseline model of the distribution of the underground rock layer resistivity in three-dimensional space; (b) Before the construction operation, first conduct self-checking on each flight control function of the unmanned aerial vehicle (1) system itself; (c) Then conduct self-checking on all the airborne data acquisition control computer system (13), fiber CO2 modulation and demodulation instrument (5), controllable electromagnetic source transmitter (6), and three-component electromagnetic field data acquisition instrument (7); (d) Subsequently, conduct self-checking on the carbon dioxide gas sensor (2), air three-component electromagnetic field sensor (3), and air horizontal controllable electromagnetic field transmitting coil (4) mounted below the unmanned aerial vehicle (1); (e) Input the flight survey line track coordinates, track elevation, track spacing, and flight speed control information required by the monitoring construction operation area into the unmanned aerial vehicle (1); (f) When the unmanned aerial vehicle (1) flies to the pre-set survey line position in the monitoring construction operation area, start the airborne data acquisition control computer system (13), fiber CO2 modulation and demodulation instrument (5), controllable electromagnetic source transmitter (6), three-component electromagnetic field data acquisition instrument (7), carbon dioxide gas sensor (2), air three-component electromagnetic field sensor (3), and air horizontal controllable electromagnetic field transmitting coil (4); (g) The various sensors mounted below the unmanned aerial vehicle (1) collect CO2 concentration data in the air and simultaneously collect the aerial three-component electromagnetic field data excited by the air horizontal controllable electromagnetic field transmitting coil (4) in the monitoring construction operation area around the high-pressure supercritical CO2 injection well along the survey line according to the pre-designed flight survey line track coordinates, track elevation, track spacing, and flight speed parameters; (h) After the aerial CO2 concentration data and aerial three-component electromagnetic field data in the monitoring construction operation area are collected, turn off the airborne controllable electromagnetic source transmitter (6), and start the ground high-power controllable current source (10) to emit alternating current to the ground large-diameter high-power electromagnetic field transmitting coil (8) or large-length high-power rectangular current source transmitting antenna (9). (i) Various sensors mounted under the unmanned aerial vehicle (1) again collect CO2 concentration data in the air along the survey line in the monitoring construction work area around the high-pressure supercritical CO2 injection well according to the pre-designed flight survey line coordinates, flight elevation, flight line spacing, and flight speed parameters, and simultaneously collect half-airborne three-component electromagnetic field data excited by the ground large-diameter high-power electromagnetic field transmitting coil (8) or large-length high-power rectangular current source transmitting antenna (9) in the underground; (j) After the CO2 concentration data collected in the monitoring construction work area around the high-pressure supercritical CO2 injection well for two consecutive times are subjected to CO2 sensor elevation correction and unmanned aerial vehicle (1) flight speed correction data preprocessing, linear or nonlinear two-dimensional interpolation processing is performed, and finally the CO2 concentration distribution map in the air at the same elevation from the ground in the monitoring construction work area around the high-pressure supercritical CO2 injection well is generated; (k) The airborne three-component electromagnetic field data collected in step (g) are subjected to elevation correction, attitude correction, flight speed correction, dip angle and azimuth angle rotation, and denoising data preprocessing of the airborne three-component electromagnetic field sensor (3), and then three-dimensional airborne three-component electromagnetic field data inversion processing is performed to obtain the distribution of resistivity anomalies in the shallow subsurface below the ground surface in three-dimensional space; (l) The half-airborne three-component electromagnetic field data collected in step (i) are subjected to elevation correction, attitude correction, flight speed, dip angle and azimuth angle rotation correction, and denoising data preprocessing of the airborne three-component electromagnetic field sensor (3), and then half-airborne three-dimensional three-component electromagnetic field data inversion processing is performed to obtain the distribution of resistivity in the deeper subsurface below the ground surface in three-dimensional space; (m) The resistivity data obtained in steps (k) and (l) in the shallow and deeper subsurface below the ground are subjected to data fusion processing to establish the accurate distribution of resistivity in the shallow and deeper subsurface below the ground in three-dimensional space; (n) After injecting high-pressure supercritical CO2 into the underground, the work procedures and data processing of steps (b) to (m) are repeated periodically to obtain the CO2 concentration distribution map in the air at the same elevation from the ground in the monitoring construction work area and the distribution of resistivity in the deeper subsurface below the ground surface in three-dimensional space after injecting high-pressure supercritical CO2 into the underground; (o) The CO2 concentration distribution data at the same elevation from the ground obtained in step (n) after injecting high-pressure supercritical CO2 into the underground are subjected to difference processing with the CO2 concentration distribution data at the same elevation from the ground measured in step (j) without injecting high-pressure supercritical CO2 into the underground; (p) The distribution of resistivity in the shallow and deeper subsurface below the ground surface in three-dimensional space obtained in step (m) after injecting high-pressure supercritical CO2 into the underground is subjected to difference processing with the distribution of resistivity in the shallow and deeper subsurface in three-dimensional space measured without injecting high-pressure supercritical CO2 into the underground; (q) analyzing the differential data of the high-pressure supercritical CO2 concentration obtained in step (o) and step (p), when the differential data of the concentration distribution of CO2 in the air at the ground elevation appears abnormal, it indicates that the high-pressure supercritical CO2 injected into the well has the risk of migration and leakage to the ground; (r) analyzing the differential data of the resistivity in the shallow and deep formations obtained in step (o) and step (p), when the differential data of the resistivity distribution in the shallow and deep formations appears abnormal, it indicates that the high-pressure supercritical CO2 injected into the well has the risk of migration and leakage to the ground; (s) when the abnormal differential data areas appearing in step (q) and step (r) substantially coincide in the projection on the ground surface, it can be substantially judged that the high-pressure supercritical CO2 injected into the well has the risk of migration and leakage to the ground, the early warning information of the possible migration and leakage of the high-pressure supercritical CO2 to the ground should be immediately sent to the high-pressure supercritical CO2 injection operation party, and the corresponding technical countermeasures and safety precautions must be taken.

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