Combined with CO 2 Underground coal gasification method in high geothermal anomaly areas combined with geological storage technology

Abstract

The present invention discloses a method for underground coal gasification in a high geothermal anomaly area combined with CO2 geological storage technology. It preferably selects coal seams that are deeply buried, have high geothermal temperatures, and have a closed caprock and are not easily developed and utilized. Supercritical CO2 is injected into the coal seams through injection wells. Affected by the formation temperature and pressure, coal and CO2 can slowly react to generate CO. During the long-term storage process, with the promotion of a catalyst, the generated CO and the displaced CH4 can reach an economically valuable reserve scale. The mixed gas in the coal seams is mined and separated and purified. The separated CO2 can be reinjected underground for reuse, and the purified CO and CH4 can be directly used industrially. This method can simultaneously achieve CO2 geological storage and the effective utilization of deep difficult-to-mine coal seams, and the process operation is simple without resource waste problems.

Description

Technical Field

[0001] The present invention relates to a method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological sequestration technology. Background Art

[0002] At present, the conventional method for underground coal gasification is to conduct controlled combustion of coal in situ. Through the pyrolysis of coal and a series of chemical reactions between coal and oxygen and water vapor, combustible gases such as H 2 , CO and CH 4 are produced. This process is also known as "coal gasification mining" or "chemical coal mining". This technology is an important supplement to traditional physical coal mining technology, realizing underground unmanned production, avoiding personal injuries and mine accidents. The gangue and ash residues after gasification remain underground, reducing the environmental impact caused by the accumulation of surface solid waste and preventing surface subsidence to a certain extent. The underground coal gasification technology is applicable to difficult-to-mine coal seams and low-grade coal seams. However, this gasification process is not easy to control, with high technical difficulty, presenting a technical barrier for small coal mines. At the same time, underground coal combustion also causes certain resource waste. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological sequestration technology, which effectively solves the problems of difficult control and serious resource waste in the process of underground coal gasification.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological sequestration technology, characterized in that:

[0006] Step 1: Optimize the target coal seam: The coal seam needs to meet the conditions that the top surface burial depth D ≥ 800m, the formation temperature T ≥ 60°C, there is a mudstone caprock above the coal seam, and the sealing property is good, that is, the permeability of the caprock is less than 0.1 millidarcy;

[0007] Step 2: Implement injection and production wells: The injection section / production section of the final hole of the well needs to be located within the target coal seam. The well completion pipe material is made of stainless steel resistant to CO 2 corrosion. The well completion technology of the well needs to meet the natural gas well completion standard. After well completion, a wellhead protection device needs to be installed at the wellhead; The distance between the injection well and the production well is preferably 200m to 2000m;

[0008] Step 3: Sealing property test: Inject supercritical CO 2, until the wellhead pressure reaches 4.5 MPa after stopping the injection, then close the wellhead protection device, and continuously monitor the wellhead pressure at a frequency higher than once every 6 hours. At the same time, monitor the CO concentration at the wellhead and spring points within 2 km of the wellhead and its surrounding area to judge the sealing property of the coal seam, that is, the CO concentration is close to the natural CO background value and there is no increasing trend; 2 Concentration, to judge the sealing property of the coal seam, that is, CO 2 Concentration is close to the natural CO 2 Background value and there is no increasing trend;

[0009] Step 4: Inject supercritical CO solution containing a catalyst; 2 Solution;

[0010] There is an obvious exothermic / endothermic process between CO2 and coal at low temperature (T≤200°C). The large enthalpy change of coal in the CO2 atmosphere indicates that CO2 can not only have a physical interaction with the coal pore interface, but may also have a chemical interaction with oxygen-containing groups. This reaction process can be explained by the following reaction formula.

[0011]

[0012] C(O)→CO (2)

[0013] When the reaction temperature is low or the CO2 pressure is low, the adsorption of CO2 on the carbon surface, that is, equation (1), is the main control reaction. When the reaction temperature is high or the CO2 pressure is high, the desorption of C(O), that is, equation (2), is the main control reaction;

[0014] The catalyst can effectively reduce the activation energy of the reaction. The oxidation-reduction reaction mechanism of the catalytic metal:

[0015]

[0016] K x O y+1 +C→K x O y +C(O) (4)

[0017] C(O)→CO (5)

[0018] In this reaction mechanism, the catalytic metal potassium cycles between the oxidation state K x O y+1 and the reduction state K x O y During the cycle, oxygen is transferred from CO 2 to carbon, thus promoting the progress of the reaction;

[0019] Compress CO 2 to the supercritical state, use the catalyst that plays a catalytic role as the solute, and prepare a supercritical CO 2 Solution, the solution concentration is about 2 - 10 g / kg; to accelerate the reaction between coal and CO2 Reaction; Evaluate the CO 2 sequestration potential according to the geological conditions of the target coal seam. Take 0.2% - 2% of the total sequestration potential as the target injection volume, and inject a supercritical CO 2 solution containing a catalyst into the coal seam. Continuously monitor the injection wellhead pressure and the CO 2 concentration at wellheads and spring points within a 2-km radius around the injection well during the injection process, that is, the CO 2 concentration shall not exceed 20 times the natural background value, the injection wellhead pressure shall not exceed 9 MPa, and the CO 2 concentration at surrounding wellheads and spring points shall not show a continuous increase. If the injection wellhead pressure exceeds 9 MPa during the injection process, immediately stop the injection and conduct continuous observation until the above indicators return to normal before continuing the injection or proceeding to the next step; if the CO 2 concentration at wellheads and spring points within a 2-km radius around the site during the injection process is greater than 20 times the natural background value, directly proceed to Step 8 (pressure relief and well sealing);

[0020] Step 5: CO 2 Geological storage: Take the evaluated CO 2 sequestration potential as the target injection volume, and inject pure supercritical CO 2 into the coal seam through the injection well. Continuously monitor the wellhead pressure and the CO 2 concentration at wellheads and spring points within a 2-km radius around the injection well during the injection process. The injection wellhead pressure shall not exceed 9 MPa, and the CO 2 concentration at surrounding wellheads and spring points shall not exceed 20 times the natural background value; if the injection wellhead pressure exceeds 9 MPa during the injection process, immediately stop the injection and conduct continuous observation until the above indicators return to normal before continuing the injection or proceeding to the next step; if the CO 2 concentration at wellheads and spring points within a 2-km radius around the site during the injection process increases significantly, directly proceed to Step 8 (pressure relief and well sealing);

[0021] Step 6: System continuous monitoring: Depressurize through the production well, and collect gas samples from the target coal seam at a frequency higher than 0.5 times / year. Proceed to the next step when the total volume ratio of CO and CH 4 gases exceeds 0.3; Continuously monitor the CO 2 concentration at the sequestration site and surrounding wellheads and spring points at a frequency that is first high and then low. If the CO 2 concentration increases significantly, that is, exceeds 20 times the natural background value, directly proceed to Step 8 (pressure relief and well sealing);

[0022] Step 7: Mixed gas production: Produce the mixed gas in the target coal seam through the production well in the form of pressure relief or negative pressure. After the mixed gas is separated and purified, the CO and CH 4 gases can be directly used industrially. The separated and purified CO 2The gas can be injected back into the ground through the injection well for reuse, and this process can achieve CO 2 Geological storage can also displace mixed gas in coal seams;

[0023] Carbon and CO in coal seams 2 Long-term reaction may cause the catalyst to deactivate. Before using this method for underground coal gasification again, step 4 should be repeated to supplement the catalyst to the target coal seam.

[0024] Step 8: Pressure relief and well sealing: If the site sealing test fails to meet the standards, or CO 2 CO generated during injection / monitoring 2 Leakage, resulting in underground coal gasification projects or CO 2 If the geological sealing project fails, the injection and production wells need to be depressurized and sealed to avoid long-term losses. After the pressure relief is completed, the pressure inside and outside the well must be equal and there must be no gas leakage from the well. Then, a cement plug is used to seal the wellhead.

[0025] Furthermore, in step 3, on the fifth day after the wellhead protection device is closed, if the wellhead pressure is >4.2MPa and the pressure drop rate is <0.015MPa / day, and within 30 days after the wellhead protection device is closed, the wellhead and spring point CO 2 If there is no increase in concentration, it means that the sealing test is good and proceed to the next step; if the monitoring results fail to meet the above conditions after closing the wellhead protection device, it means that the sealing test is poor and go directly to step 8 (pressure relief and well sealing).

[0026] The catalyst is a mixture of potassium oxide, aluminum oxide and nickel or tungsten sulfide.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention can simultaneously realize CO 2 Geological storage and effective utilization of deep and difficult-to-mine coal seams are the key to CO 2 New directions in the field of geological utilization and storage technology.

[0029] (2) The present invention targets coal seams that are difficult to develop and utilize because they are deeply buried underground, have high ground temperatures, and have good cap rock sealing properties, thereby achieving effective utilization of difficult-to-mine coal seams.

[0030] (3) In the present invention, under the conditions of high ground temperature and high formation pressure, coal and CO 2 The reaction to generate CO can proceed spontaneously without the need for complex human control processes.

[0031] (4) The mixed gas generated by the present invention contains no O 2 The method for separating and purifying CO and CH4 is simple, and there is no explosion hazard during combustion.

[0032] (5) The CO separated and purified from the mixed gas of the present invention 2 can be directly reinjected underground. During this process, while achieving the geological sequestration of CO 2 , it has the effect of displacing the mixed gas and promoting development.

[0033] (6) The underground coal gasification method provided by the present invention in combination with the CO2 geological sequestration technology, while achieving the geological storage of CO2, solves the problems of difficult control and serious resource waste in the underground coal gasification process described in the above background technology. The present invention takes the coal seam that is deeply buried underground, has a high geothermal temperature, and has good caprock sealing and is not easily exploited and utilized as the target coal seam, and injects supercritical CO2 into the coal seam through an injection well to achieve the purpose of CO2 geological sequestration. During this sequestration process, affected by the formation temperature and pressure, coal and CO2 can slowly react to generate CO. During the long-term sequestration process, with the promotion of a catalyst, the generated CO and the displaced CH4 can reach an economically valuable reserve scale. The mixed gas in the coal seam is mined and separated and purified. The separated CO2 can be reinjected underground for reuse, and the purified CO and CH4 can be directly used industrially. This underground coal gasification technology method is simple to operate and has no resource waste problem. While achieving the geological sequestration of CO2, it can effectively utilize deep and difficult-to-mine coal seams. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the flow chart of the underground coal gasification in combination with the CO2 geological sequestration technology in the present invention.

[0035] Figure 2 is the engineering structure schematic diagram of the underground coal gasification in combination with the CO2 geological sequestration technology in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following only uses examples to illustrate the possible implementation modes of the present invention, but is not intended to limit the scope of protection of the present invention, which is hereby stated first.

[0037] As Figure 1 and Figure 2 shown, it is a method for underground coal gasification in a high geothermal anomaly area in combination with the CO2 geological sequestration technology of the present invention:

[0038] The specific steps include:

[0039] Step 1: Optimize the target coal seam;

[0040] Step 2: Implement injection and production drilling;

[0041] Step 3: Conduct sealing test;

[0042] Step 4: Inject catalyst;

[0043] Step 5: CO2 geological storage;

[0044] Step 6: System continuous monitoring;

[0045] Step 7: Mixed gas extraction;

[0046] Step 8: Pressure relief and well sealing.

[0047] The following will be described in detail one by one.

[0048] First, collect the existing drilling, logging or geophysical exploration data of the coalfield, and select the coal seams that are not easily exploited and utilized with a top surface burial depth D≥800m, formation temperature T≥60°C, overlying mudstone caprock and good sealing.

[0049] Implement the injection well 1a, with a drilling depth >800m, and the final injection section of the well needs to be located in the coal seam. The drilling needs to be constructed in accordance with the well completion standard of natural gas drilling, and the well completion pipe is made of stainless steel pipe resistant to CO 2 corrosion. Install a wellhead protection device (1) at the wellhead, and connect a barometer (2) to the wellhead protection device. Install a CO 2 concentration monitoring station (8) within 10m around the injection wellhead. Install a CO 2 concentration monitoring station (9) at shallow wells and spring outlets within 2km around.

[0050] Implement the production well 1b, with a spacing of 200m - 2000m between the production well 1b and the injection well 1a. The well completion requirements for the production well are the same as those for the injection well, with a well depth >800m, and the final injection section of the well needs to be located in the coal seam. Install a protection device (3) at the drilling wellhead, install a gas composition analyzer (4) on the wellhead protection device, and close the wellhead valve switch (b).

[0051] Sealing test of the well site. Compress the CO 2 gas source (5) to the supercritical state through a high-pressure injection pump (7), inject it into the coal seam through the injection well 1a, monitor the barometer (2) until the wellhead pressure reaches 4.5MPa after stopping injection, then close the wellhead valve switch (a), and continuously monitor the pressure of the wellhead barometer (2) at a frequency higher than 6 hours each time. At the same time, monitor the CO 2 concentration of the CO 2 concentration monitoring station (8) at the wellhead and the CO 2 concentration of the concentration monitoring stations (9) at wellheads and spring points within 2km around. On the 5th day after closing the wellhead valve switch (a), if the pressure of the wellhead barometer (2) >4.2MPa and the pressure drop rate <0.015MPa / day, and within 30 days after closing the wellhead protection device, the CO 2 concentration of the CO 2 concentration monitoring station (8) at the wellhead and the CO 2 concentration of the concentration monitoring stations (9) at wellheads and spring points within 2km around does not increase, that is, the CO2 Background value (CO concentration in the atmosphere) 2 is close to that without an increasing trend, indicating that the sealing test is good and the next step can be carried out. If the monitoring results fail to meet the above conditions, it indicates that the sealing test is poor and the well should be directly depressurized and sealed.

[0052] CO2 and coal have an obvious exothermic / endothermic process at low temperature (T≤200°C). The large enthalpy change of coal in the CO2 atmosphere indicates that CO2 can not only have a physical interaction with the coal pore interface, but may also have a chemical interaction with oxygen-containing groups. This reaction process can be explained by the following reaction formula.

[0053]

[0054] C(O)→CO (2)

[0055] When the reaction temperature is low or the CO2 pressure is low, the adsorption of CO2 on the carbon surface, i.e., equation (1), is the main controlling reaction. When the reaction temperature is high or the CO2 pressure is high, the desorption of C(O), i.e., equation (2), is the main controlling reaction;

[0056] The catalyst can effectively reduce the activation energy of the reaction, and the oxidation-reduction reaction mechanism of the catalytic metal is as follows:

[0057]

[0058] K x O y+1 +C→K x O y +C(O) (4)

[0059] C(O)→CO (5)

[0060] In this reaction mechanism, the catalytic metal potassium cycles between the oxidation state K x O y+1 and the reduction state K x O y During the cycle, oxygen is transferred from CO 2 to carbon, thus promoting the reaction; the gasification reaction rate of carbon in this reaction process is proportional to the concentration of the surface oxide of the catalytic metal.

[0061] The CO 2 gas source (5) and the catalyst are made into a supercritical CO 2 solution through a high-pressure sealed solution stirrer (6), and the solution concentration is about 2 - 10 g / kg.

[0062] Evaluate CO 2Seal the potential, with the injection volume targeted at 0.2% - 2% of the total sealing potential, and inject the supercritical CO containing catalyst into the coal seam through the high-pressure injection pump (7) and the injection well 1a. 2 solution.

[0063] After completing the injection of the supercritical CO containing catalyst 2 solution, with the geological sealing potential of CO 2 as the target injection volume, inject pure supercritical CO into the coal seam through the high-pressure injection pump (7) and the injection well 1a. 2 .

[0064] During the injection process, continuously monitor the pressure of the barometer (2) at the injection wellhead, the CO2 concentration monitoring station (8) at the wellhead, and the CO 2 concentration of the concentration monitoring stations (9) at the wellheads and spring points within 2 km around. 2 The pressure of the barometer (2) at the injection wellhead shall not exceed 9 MPa, and the CO 2 concentration of the concentration monitoring station (8) at the wellhead and the CO 2 concentration of the concentration monitoring stations (9) at the wellheads and spring points within 2 km around 2 shall not show a significant increase, that is, the CO 2 concentration shall not exceed 20 times the natural background value. If the pressure of the barometer (2) at the injection wellhead exceeds 9 MPa during the injection process, immediately stop the injection and conduct continuous observation until the above indicators return to normal and then continue the injection or enter the system continuous monitoring stage.

[0065] During the injection process and after the CO 2 sealing is completed, if the CO 2 concentration of the concentration monitoring station (8) at the wellhead and the CO 2 concentration of the concentration monitoring stations (9) at the wellheads and spring points within 2 km around 2 significantly increases, that is, the CO 2 concentration is greater than 20 times the natural background value, directly relieve the pressure and seal the well.

[0066] After the CO 2 sealing is completed, collect the gas samples of the target coal seam at a frequency higher than 0.5 times / year, and analyze the gas sample composition through the gas component analyzer (4) on the wellhead protection device (3) of the production well or send it to the laboratory for testing. When the total volume ratio of CO and CH 4 gases exceeds 0.3, it indicates that the mixed gas in the coal seam has the value of development and utilization.

[0067] Open the valve switch (b), and the mixed gas with economic value is mined to the surface. After passing through the CO 2 separation and purification equipment (10) to separate and purify CO 2 , and the purified CO 2After being compressed to the supercritical state by the valve switch (d) and the high-pressure injection pump (7), it is directly reinjected underground; it can also pass through the valve switch (c) and the high-pressure closed solution stirrer (6) to make a supercritical CO 2 solution containing a catalyst, and the catalyst is replenished into the coal seam through the high-pressure injection pump (7) and the injection well. After the mixed gas is purified of CO 2 the remaining CO and CH 4 can be sealed in the CO and CH 4 gas storage reservoir (11), and the stored CO and CH 4 can be directly used industrially.

[0068] This process can be repeated. After the production of the mixed gas is completed, the purified CO 2 is reinjected underground again. After the catalyst is replenished, the system enters the continuous monitoring state again. In the mixed gas generated by the long-term reaction of coal and CO 2 in the coal seam, when the volume ratio of CO and CH 4 reaches 0.3, it can be mined and utilized again.

[0069] The present invention aims at a coal seam that is buried deep underground, has a high geothermal temperature, and has a good caprock sealing property and is not easily exploited. Supercritical CO is injected into the coal seam through an injection well 2 to achieve the purpose of geological sequestration of CO 2 During this sequestration process, affected by the formation temperature and pressure, coal and CO 2 can slowly react to generate CO. During the long-term sequestration process, and with the promotion of a catalyst, the generated CO and the displaced CH 4 can reach an economically valuable reserve scale. The mixed gas in the coal seam is mined and separated and purified. The separated CO 2 can be reinjected underground for reuse, and the purified CO and CH 4 can be directly used industrially. This underground coal gasification technology method is easy to operate and has no problem of resource waste. While realizing the geological sequestration of CO 2 it can effectively utilize deep and difficult-to-mine coal seams. The underground coal gasification method provided by the present invention combined with the CO 2 geological sequestration technology realizes the geological storage of CO 2 while solving the problems of difficult control and serious resource waste in the underground coal gasification process described in the above background technology.

Claims

1. A method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological sequestration technology It is characterized in that: Step 1: Optimize the target coal seam: The coal seam should meet the requirements that the top surface burial depth D≥800m, the formation temperature T≥60°C, there is a mudstone caprock overlying the coal seam, and the sealing property is good, that is, the permeability of the caprock is less than 0.1 millidarcy; Step 2: Implement injection and production wells drilling: The injection section / production section at the end of the well drilling should be located within the target coal seam, and a wellhead protection device should be installed at the wellhead after completion of the well; The distance between the injection well and the production well is preferably 200m - 2000m; Step 3: Sealing test: Inject supercritical CO₂ into the preferred target coal seam through the injection well at a rate of less than 20 kg / s 2 , until the wellhead pressure reaches 4.5 Mpa after stopping the injection, then close the wellhead protection device, and continuously monitor the wellhead pressure at a frequency higher than once every 6 hours. At the same time, monitor the CO₂ concentration at the wellhead and spring points within 2 km around the wellhead to judge the sealing of the coal seam, that is, the CO₂ concentration is close to the natural CO₂ background value and there is no increasing trend; 2 concentration to judge the sealing of the coal seam, that is, the CO₂ 2 concentration is close to the natural CO₂ 2 background value and there is no increasing trend; Step 4: Inject supercritical CO containing a catalyst 2 solution; Compress CO 2 to the supercritical state, use the catalyst that plays a catalytic role as the solute, and prepare a supercritical CO 2 solution with a solution concentration of about 2 - 10 g / kg; To accelerate the reaction between coal and CO 2 ; Evaluate the CO 2 sequestration potential according to the geological conditions of the target coal seam, and use 0.2% - 2% of the total sequestration potential as the target injection volume, and inject the supercritical CO containing a catalyst 2 solution into the coal seam. During the injection process, continuously monitor the injection wellhead pressure and the CO 2 concentration at the wellheads and spring points within 2 km around the perimeter. That is, the CO 2 concentration shall not exceed 20 times the natural background value, the injection wellhead pressure shall not exceed 9 MPa, and the CO 2 concentration at the wellheads and spring points around the perimeter shall not show a continuous increase; If the injection wellhead pressure exceeds 9 MPa during the injection process, immediately stop the injection and conduct continuous observation until the wellhead pressure returns to normal and then continue the injection or proceed to the next step; If the CO 2 concentration at the wellheads and spring points within 2 km around the site perimeter is greater than 20 times the natural background value, directly proceed to Step 8; Step 5: CO 2 Geological storage: Inject pure supercritical CO into the coal seam through the injection well with the evaluated CO 2 sequestration potential as the target injection volume. During the injection process, continuously monitor the wellhead pressure and the CO 2 concentrations at the wellheads and spring points within a 2-km radius around the injection well. The wellhead pressure at the injection well shall not exceed 9 MPa, and the CO 2 concentrations at the surrounding wellheads and spring points shall not exceed 20 times the natural background value; if the wellhead pressure at the injection well exceeds 9 MPa during the injection process, immediately stop the injection and conduct continuous observations until the wellhead pressure at the injection well returns to normal and then continue the injection or proceed to the next step; if the CO 2 concentrations at the wellheads and spring points within a 2-km radius around the site are greater than 20 times the natural background value and show an increasing trend during the injection process, directly proceed to Step 8; 2 ​ Step 6: System continuous monitoring: By relieving pressure through the production well, gas samples of the target coal seam are collected at a frequency higher than 0.5 times / year. When the total volume ratio of CO and CH 4 exceeds 0.3, proceed to the next step; Continuously monitor the CO 2 concentrations of the storage site and the surrounding wellheads and spring points at a frequency that is high first and then low. If the CO 2 concentration exceeds 20 times the natural background value and shows an increasing trend, directly proceed to Step 8; Step 7: Mixed gas production: The mixed gas in the target coal seam is produced through the production well in the form of pressure relief or negative pressure. After the mixed gas is separated and purified, CO and CH 4 gas is directly utilized industrially. The purified CO 2 gas is reinjected underground through the injection well for reuse. This process can not only achieve CO 2 geological sequestration, but also displace the mixed gas in the coal seam; Step 8: Pressure relief and well sealing: If the site closure test fails, or CO 2 leakage occurs during the CO injection / monitoring process, resulting in the failure of the underground coal gasification project or the CO 2 geological storage project. To avoid long-term losses, it is necessary to relieve the pressure of the injection-production well and seal it. After the pressure relief is completed, it is necessary to ensure that the pressure inside and outside the well is balanced and there is no gas overflow in the well. Subsequently, the wellhead is sealed with a cement plug. 2 ​ 2. The method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological storage technology as claimed in claim 1, It is characterized in that: In step 4: CO 2 and coal have an obvious exothermic / endothermic process at low temperature (T≤200°C). The coal in the CO 2 atmosphere with a large enthalpy change indicates that CO 2 not only has a physical interaction with the coal pore interface, but also has a chemical interaction with oxygen-containing groups. This chemical interaction can be explained by the following reaction formula: （1） （2） When the reaction temperature is low or the CO 2 pressure is low, the adsorption of CO 2 onto the carbon surface, i.e., equation (1), is the main rate-controlling reaction. While when the reaction temperature is high or the CO 2 pressure is high, the desorption of C(O), i.e., equation (2), is the main rate-controlling reaction; The catalyst can effectively reduce the activation energy of the reaction, and the oxidation-reduction reaction mechanism of the catalytic metal is as follows: （3） （4） （5） In this reaction mechanism, the catalytic metal potassium cycles between the oxidized state K x O y+1 and the reduced state K x O y During the cycle, oxygen is transferred from CO 2 to carbon, thus promoting the progress of the reaction.

3. The underground coal gasification method in high geothermal anomaly areas combined with CO 2 geological sequestration technology It is characterized in that: In Step 3, on the 5th day after closing the wellhead protection device, if the wellhead pressure > 4.2 MPa, the pressure drop rate < 0.015 MPa / day, and within 30 days after closing the wellhead protection device, the CO 2 concentration at the wellhead and spring points within the site and within a 2-km radius does not increase, it indicates that the sealing test is satisfactory and the next step can be entered; If the monitoring results do not meet the above conditions after closing the wellhead protection device, it indicates that the sealing test is poor, and directly enter Step 8.

4. The method for underground coal gasification in high geothermal anomaly areas combined with CO 2 geological storage technology as claimed in claim 1 It is characterized in that: The catalyst is a mixture of potassium oxide, aluminum oxide and nickel or tungsten sulfide.

5. The underground coal gasification method in high geothermal anomaly areas combined with CO 2 geological sequestration technology It is characterized in that: Coal and CO in coal seams 2 The long-term reaction can cause the catalyst to deactivate, and it is necessary to repeat the method of underground coal gasification in high geothermal anomaly areas combined with geological sequestration technology with CO 2 to step 4, and supplement the catalyst to the target coal seam.

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