162 results about "Underground coal gasification" patented technology

The invention relates to the technical field of underground coal gasification, in particular to a coal underground gasification process stability monitoring and evaluating method which comprises the following steps: determining a space mapping relation between a gasifier temperature field and an acoustic emission event according to the temperature gradient and the acoustic emission event of a gasifier; carrying out three-dimensional inversion on a combustion cavity of the gasification furnace, and determining attenuation trends of the coal seam under different temperature gradients; according to the attenuation trend of the coal seam under different temperature gradients, the propelling direction of the boundary of the combustion cavity is determined by utilizing the spatial distribution density and the relative position of each acoustic emission event; according to the propelling direction of the fuel cavity boundary, boundary moving paths are formed, and the propelling area proportion of each position in the propelling direction is calculated according to the distance difference of the boundary moving paths; and according to the propulsion area proportion of each position in the propulsion direction and the expansion rate of the combustion cavity, determining the space stability classification of each part of the combustion cavity. The accuracy and the efficiency of monitoring underground gasification of the coal seam are realized.

The invention relates to the technical field of coal underground gasification control, in particular to a stable control method for the gasification process of deep coal passing through dirt band. The gas pressure distribution data and the pore change characteristic data of the deep coal gasification area are collected in real time through the distributed sensor array, the gas dynamic correction permeability is generated, the gas injection pressure is adjusted and dynamically corrected according to the gas dynamic correction permeability, and the gas pressure is kept stable; screening a potential risk area through a main stress direction deviation angle and a stress concentration coefficient in the dirt band layer, analyzing a shear stress threshold value of the potential risk area based on a stress-strain coupling model, and judging a stability evaluation index of the potential risk area; and when the stability evaluation index is lower than a threshold value, a multi-stage emergency regulation and control mechanism is triggered, and a dirt band layer reinforcement intervention scheme is generated. By means of multi-source data fusion and a dynamic feedback mechanism, the limitation of a traditional method for lagging response of the instability risk of the dirt band layer is broken through, and full-closed-loop intelligent stable control over the gasification process is achieved.

The invention discloses a coal seam group occurrence three-area linkage gas extraction method. Firstly, a coal seam is divided into an underground coal gasification area, a pressure relief permeability increasing area and an original extraction area; in the initial stage of underground coal gasification, in the process that high-temperature combustible gas generated by underground coal gasification is injected into a ground drilling well, the high-temperature combustible gas and a coal body are subjected to heat transfer, so that the temperature of the coal body is increased, and gas desorption is enhanced; under the continuous coupling action of high temperature and high pressure of the high-temperature combustible gas, the permeability of the coal body is improved; in the process that high-temperature combustible gas is injected into the ground drilling well, gas extraction is continuously conducted on other adjacent drilling holes; under the condition that gas injection and gas extraction are sequentially and circularly performed in ground drilling, the coal body is circularly impacted by positive pressure-negative pressure alternating aerodynamic force, and further fracturing of the coal body is facilitated; under the triple effects of high-temperature coal body gas desorption strengthening, coal body permeability increasing and gas displacement, large-flow and high-quality extraction of deep coal seam gas is finally achieved.

The invention belongs to the technical field of coal bed gas exploitation, and particularly relates to a method for achieving multiple purposes of a coal bed gas horizontal well. Firstly, a horizontal well is constructed in a coal seam, staged fracturing is conducted to increase permeability, coal bed gas ground extraction is achieved, when the coal bed gas yield cannot reach the economic recoverable condition, coal underground gasification is conducted through the horizontal well, and finally carbon dioxide obtained after gasification separation or other output is injected for storage through underground residual coal and coal cinder gaps. Multiple purposes of the coal bed gas horizontal well are achieved; through one-well multi-stage utilization, the functions of coal bed gas extraction, coal underground gasification, carbon dioxide storage and the like are achieved step by step, and the comprehensive cost is reduced by 40% or above.

The invention discloses a coal underground gasification mining front and rear furnace common well continuous coordination propulsion method which comprises the following steps: S1, constructing a gas inlet well and a gas outlet well of a first furnace, and performing gas injection fracturing on a gasification to-be-mined area of the first furnace by using the gas outlet well; s2, coal seam combustion gasification operation is conducted on the gasification to-be-mined area of the first furnace, and synthesis gas is collected through a gas outlet well of the first furnace; meanwhile, a gas outlet well of the second furnace is used for conducting gas injection fracturing on the gasification to-be-mined area of the second furnace; s3, the combustion space area of the first furnace is made to be idle for cooling, meanwhile, the second furnace conducts combustion gasification operation, and the third furnace conducts gas injection fracturing operation; each furnace is subjected to a flow process of gas injection fracturing, combustion gasification, idle cooling and CO2 storage well closing treatment; and S4, completing each flow process in sequence. The upper furnace and the lower furnace carry out difference node follow-up according to the flow process by one flow node, the upper furnace and the lower furnace carry out well sharing, the number of drilled wells is reduced, geological damage is relieved, and the mining efficiency is improved.

The invention relates to the field of clean energy development and utilization, in particular to an underground coal gasification method with high-temperature steam as a gasifying agent and an experimental device. The method comprises the steps of exploration, well building, permeability increasing, gasification, coal gas utilization and waste treatment, the experimental device comprises a steam generator and a gasification furnace, the steam generator injects high-temperature steam into the gasification furnace, the high-temperature steam is used for coal gasification, in the gasification step, the high-temperature steam is injected into a coal seam, and the high-temperature steam is used for coal gasification. The high-temperature steam serving as a gasifying agent is subjected to a series of reactions with the coal, the high-temperature steam is gasified to generate coal gas through chemical reaction with the coal, and the high-temperature steam is also used for heating the coal to pyrolyze the coal to generate coal gas; according to the method, oxygen is not directly injected into the coal seam, the coal seam is not ignited, and combustion of coal is not involved, but high-temperature steam is injected into the coal seam, the underground coal gasification process is completed through the oxidation-reduction reaction and the distillation pyrolysis action of the high-temperature steam and the coal, and the raw gas is generated.

The invention discloses a numerical simulation method and system for a coal underground gasification process, and belongs to the technical field of energy development. The method comprises the following steps: constructing a gasification cavity, cavity wall and raw coal three-area conceptual model; establishing a kinetic model coupled with five types of chemical reactions (complete oxidation, water vapor conversion, Boudouard reaction, hydrogenization and water-gas shift), and associating porosity change and cavity wall temperature gradient distribution; dynamic evolution prediction of the semi-teardrop-shaped gasification cavity is realized through a numerical flow of cyclically updating the porosity, marking the cavity, calculating the reaction and outputting the synthesis gas; a cavity form and synthesis gas component curve is generated based on a multi-module system (data preparation, numerical calculation, result analysis and visualization). The problem that the gasification cavity evolution simulation precision is insufficient in the prior art is solved, and the method is suitable for UCG engineering design and safety evaluation.

The invention belongs to but not limited to the technical field of underground coal gasification, and discloses an underground coal gasification method and gas injection equipment. Constructing a directional drill hole and a gasification channel penetrating through the underground coal seam; a gas injection pipe with a plasma torch is put into the gasification channel, a gasification agent is injected, and in-situ gasification of the underground coal seam is implemented; and the generated gas is conveyed to the ground for collection through the drill hole. According to the underground coal gasification method and the gas injection equipment provided by the invention, the gasification agent is activated by the plurality of plasma torches arranged in the directional channel at the tail end of the gas injection pipe and then is directionally jetted to the coal seam, so that the gasification agent is in contact with the coal seam in a short time and is gasified, the directional conveying of the plasma gasification agent is realized, and the effective utilization rate of the plasma gasification agent is improved; meanwhile, a combustion space area of the coal seam after gasification can be expanded in a fan shape in the longitudinal direction with the gasification agent outlets of the plasma torches as the center, the expansion equivalent radius of the combustion space area is relatively large, and a large amount of coal can be gasified through one gasification channel.

The invention relates to the technical field of coal underground gasification site selection, and discloses a coal underground gasification site selection system and method based on multi-parameter collaborative evaluation.The coal underground gasification site selection method comprises the following steps that coal resource data of a target area are collected and examined, and influence factors are screened and analyzed; comparing the collected coal resource data with corresponding influence factor evaluation standards, and respectively obtaining each factor estimated value of the corresponding influence factor; calculating the suitability coefficient of each factor of the influence factors and the average suitability coefficient of the influence factors according to the estimation condition of each factor of the target area influence factors; according to the method, a complete multi-dimensional evaluation index system is constructed, the coal bed gasification suitability is comprehensively evaluated from multiple dimensions, and the one-sidedness of evaluation is avoided; meanwhile, a scientific quantitative evaluation mechanism is established, qualitative factors are converted into quantitative indexes through grade quantification, and the objectivity and scientificity of evaluation are improved by combining dimensionless processing and weight distribution.

The invention discloses a coal underground gasification injection-production well pattern determination method, device and equipment and a medium. The method comprises the steps that an injection well site is determined according to a gasification control area of a target reservoir development body, and an injection well bore structure is determined according to injection conditions and coal seam parameters corresponding to the gasification control area; determining a migration path concentration area and an enrichment area of preset generated gas, and determining a production well site according to the migration path concentration area and the enrichment area of the preset generated gas; and according to the injection well site, the injection well body structure and the production well site, coal underground gasification injection-production well pattern distribution of the target reservoir development body is determined. According to the technical scheme, by selecting the proper injection well site, the injection well body structure and the production well site, coal underground gasification injection-production well pattern distribution is determined, coal underground gasification injection-production well pattern deployment is achieved, and the coal seam combustion rate and the preset generated gas recovery rate are increased.

The invention relates to the technical field of underground coal gasification, and provides an active cooling method and an active cooling device for underground coal gasification, and the method comprises the following steps: capturing carbon dioxide generated in a gasification process; the captured carbon dioxide is cooled and stored; after gasification is finished, a sealing material is injected into the production well and an annular gap generated in the gasification process, so that the gasification cavity is kept airtight; and the stored carbon dioxide is pressurized and injected into the gas injection well. A carbon dioxide gas injection active cooling mode is adopted, and it is ensured that the inner wall of a combustion space area cannot generate cracks due to drastic temperature change; moreover, carbon dioxide in the gasification process is used as a coolant, so that the collaborative operation of gasification and carbon sealing can be realized, and the target of zero emission is achieved.

The invention relates to the technical field of permeability calculation, and discloses a method for predicting the high-temperature permeability of coal underground gasification surrounding rock based on a thermal stress model, which comprises the following steps: collecting samples, and preprocessing the samples to determine mineral components of the samples; carrying out heat treatment on the sample at different temperature levels, and then carrying out experimental testing to obtain parameters of the sample; simulating, coupling and calculating the strain energy of the sample by adopting a finite element method, and calculating the fracture amount by combining the strain energy and the geometrical shape of the fracture at high temperature; and calculating and predicting the high-temperature permeability by using the geometrical shape and the fracture amount of the fracture at high temperature. According to the method, finite element thermal stress simulation and fracture mechanics theories are combined, the stress causing fracture is accurately calculated, the fracture amount is calculated in combination with observation of the geometrical shape of the fracture after high temperature action under a microscopic image, and the fracture seepage rate is calculated based on the fracture amount and discontinuity of sudden change of the high-temperature seepage rate of the geometrical shape of the fracture after high temperature action. And the high-temperature permeability is calculated and predicted, and the method has very strong prediction performance.

The present invention discloses a method for in-situ collaborative development of coal-rock-sandstone type uranium deposits. Uranium resources in coal-rock and sandstone type uranium deposits are mined by combining underground coal gasification with in-situ neutral (CO2+O2) in-situ leaching. This method can achieve clean utilization of coal resources through gasification and collaborative development of sandstone and coal-rock type uranium resources. The method has the advantages of low energy consumption, high resource recovery rate, simple process, and low environmental impact. It conforms to the concept of green mining and is of great significance for addressing my country's demand for strategic key metallic uranium resources and protecting the environment.

This invention discloses an underground ignition tool and its operating method for underground coal gasification processes, comprising: a casing with a tool connector inside; an oxygen injection tool connected to the tool connector inside the casing, the oxygen injection tool having a water channel and an oxygen interface; a connector shell fixedly fitted onto the outer side of the tool connector; a hydraulic piston movably disposed within the inner cavity of the connector shell; a separation shell detachably connected to the bottom of the inner wall of the connector shell; and an oxygen pressure piston movably engaged within the inner cavity of the separation shell. This underground ignition tool and its operating method for underground coal gasification processes perfectly solve the technical problem of underground gasifiers being unable to operate continuously and requiring shutdown and closure, while also possessing significant advantages such as simple operation and convenient installation.

The present invention belongs to, but is not limited to, the technical field of underground coal gasification, and discloses an underground coal gasification method and gas injection equipment; constructs a directional borehole and a gasification channel that penetrates an underground coal seam; lowers a gas injection pipe carrying a plasma torch into the gasification channel and injects a gasifying agent to implement in-situ gasification of the underground coal seam; and the generated coal gas is transported to the surface through the borehole for collection. The underground coal gasification method and gas injection equipment proposed by the present invention activate the gasifying agent through multiple plasma torches built into the directional channel at the end of the gas injection pipe and then directionally injects it into the coal seam. The gasifying agent contacts and gasifies the coal seam in a relatively short period of time, thereby achieving directional transportation of the plasma gasifying agent and improving the effective utilization rate of the plasma gasifying agent, thereby increasing the effective component content of the coal gas. At the same time, the combustion zone of the coal seam after gasification will expand in a fan-shaped manner longitudinally with the gasifying agent outlet of each plasma torch as the center. The expansion equivalent radius of the combustion zone is relatively large, and a single gasification channel can gasify a large amount of coal.

The invention discloses coal underground gasification simulation experiment equipment and method.The equipment comprises a screening mechanism, the screening mechanism comprises a screening shell and screening assemblies, a plurality of sliding grooves are obliquely formed in the screening shell in the vertical direction, and the screening assemblies are slidably arranged in the sliding grooves; a feeding port is formed in the top of the screening shell, a first material guiding plate is obliquely and fixedly arranged at the feeding port, a plurality of material conveying plates are obliquely and fixedly arranged in the screening shell in the vertical direction, the screening assembly comprises two arc-shaped screening bases, a first screening net, a second screening net and a material pushing assembly, and the screening bases are arranged in the screening shell. Supporting plates are fixedly arranged on the screening bases in an inclined mode, a first screening net is fixedly arranged between the two supporting plates, an arc-shaped second screening net and an arc-shaped check ring are fixedly arranged between the two screening bases, two openings are formed between the arc-shaped check ring and the second screening net, and the material pushing assembly is rotationally arranged on the screening bases.

This application discloses an in-situ permeability testing system for underground coal gasification, including a core holder comprising a cylinder, a seepage ring, an axial pressure loading component, a gas pipeline, a sealing assembly, a confining pressure sleeve, a core heating element, a temperature and flow rate measurement assembly, an inlet gas pressure measurement assembly, an outlet gas pressure measurement assembly, and a permeability calculation assembly. The system can calculate the permeability of the core using the core holder outlet temperature, outlet flow rate, inlet gas pressure, and outlet gas pressure, combined with the core's dimensional parameters and the gas viscosity at the core holder outlet temperature. This system can simulate the high-temperature, high-pressure, and high-stress environment of deep underground coal gasification and directly perform in-situ core permeability testing, better ensuring the accuracy and reliability of the test results. This application also discloses an in-situ permeability testing method for underground coal gasification.

This invention discloses a drilling-type gas leakage recovery device for underground coal gasification, comprising a scissor lift system. Each scissor lift consists of two rods rotatably connected at their centers. Multiple sets of scissor lifts are hinged together at their ends. A central sleeve is rotatably provided at the center of the central scissor lift, through which an external extraction pipe passes. A drill bit is fixed to the lower end of the external extraction pipe. Side sleeves are rotatably provided at the centers of the remaining scissor lifts, each containing a drill rod. Compared to existing technologies, this invention provides a sealing effect on the entire formation fracture, preventing gas leakage. The external extraction pipe, each drill rod, and each set of scissor lifts are integrated into a single unit, improving the stability of the external extraction pipe.

The invention provides an underground coal gasification ignition device and method, relates to the technical field of underground coal gasification, and aims to improve the ignition success rate and the ignition reliability. The underground coal gasification ignition device comprises a multi-channel continuous pipe, a combustor, a first release sub and an ignition structure which are connected in sequence. A fuel injection channel and an oxygen injection channel are arranged in the multi-channel continuous pipe and the combustor, a nozzle is arranged in the combustor, and the fuel injection channel and the oxygen injection channel are both communicated with the nozzle. A first connecting piece is arranged between the first releasing sub and a shell of the ignition structure in a penetrating mode, and when the load borne by the first connecting piece is larger than a first preset load, the first connecting piece is broken, so that the first releasing sub is separated from the ignition structure. A spraying hole facing the nozzle is formed in a shell of the ignition structure, ignition equipment and a grain are arranged in the shell of the ignition structure, after the first connecting piece is broken, the ignition equipment ignites the grain to form ignition flames, the ignition flames are sprayed out from the spraying hole, fuel is ignited, and then the coal seam is ignited.

The present invention discloses a combustible casing for an underground coal gasification channel and a preparation method thereof, belonging to the technical field of petroleum industry pipe manufacturing. The preparation process of the combustible casing is simple. The combustible casing is composed of 0.2-1.0Zr, 1.0-5.0Zn, 1.0-5.0Al, 7.0-13.0Gd, 3.0-6.0Y, 3.0-6.0Nd, and the remainder being Mg and impurities in mass percentage. After being cast and turned into an ingot, the ingot is solution treated and extruded, and then subjected to aging treatment. Finally, the combustible casing is prepared, which has sufficient space for normal operation and has the characteristic of being burned and consumed above a specific temperature. The casing has a rationally designed alloy element composition, low density, high specific strength, excellent room temperature and high temperature strength, and the characteristics of being burned and consumed above the specific temperature.

The application discloses a numerical simulation method and system for a coal underground gasification process and belongs to the technical field of energy development. The method comprises the following steps: constructing a conceptual model of a gasification cavity, a cavity wall and a raw coal three-zone; establishing a kinetic model coupled with five types of chemical reactions (complete oxidation, steam conversion, Boudouard reaction, hydrogen gasification and water gas shift); correlating the porosity change and the cavity wall temperature gradient distribution; realizing the dynamic evolution prediction of a semi-teardrop-shaped gasification cavity through a numerical process of cyclically updating the porosity, marking the cavity, calculating the reaction and outputting the synthesis gas; and generating the cavity shape and the synthesis gas component curve based on a multi-module system (data preparation, numerical calculation, result analysis and visualization). The application solves the problem of insufficient simulation precision of the gasification cavity evolution in the prior art and is suitable for UCG engineering design and safety evaluation.

The utility model relates to an underground well drilling heat exchange system based on a heat pipe, a heat pipe heat exchanger of the system is arranged in a production well, an evaporation section of the heat pipe is arranged on the outer wall of the heat pipe heat exchanger, a heat source is high-temperature coal gas generated by underground coal gasification, and a condensation section of the heat pipe is arranged on the inner wall of the heat pipe heat exchanger to exchange heat with water; a water inlet of the heat pipe exchanger is provided with a straight pipe communicated to the bottom of the heat pipe exchanger, and a water outlet of the heat pipe exchanger is arranged on the ground; the coal gas generated by the gasification furnace is cooled by the heat pipe heat exchanger and then sequentially enters the condensation tank, the water-gas shift device and the acid gas removal device to be purified, and then the coal gas can be used for hydrogen production, natural gas synthesis, IGCC power generation and the like. According to the utility model, the temperature of the underground coal gasification production well is rapidly reduced by utilizing the high thermal conductivity and the automatic heat transfer characteristic of the heat pipe, the stable operation of underground coal gasification is guaranteed, the utilization rate of energy is improved, and the loss of a large amount of sensible heat of coal gas is effectively avoided.

The invention relates to the technical field of underground coal gasification gas purification, in particular to an efficient gas filtering device for an underground coal gasification curve type production well, which comprises a conveying channel, a gas inlet channel, a gas outlet channel and a gas outlet channel, the first bend is used for connecting the inlet channel and the connecting channel, and a plurality of first spiral ribs which are spirally arranged are arranged in the first bend; the second bend is used for connecting the connecting channel and the discharging channel, and a plurality of second spiral ribs which are spirally arranged are arranged in the second bend; according to the fine filtration unit, the separation efficiency can be improved by utilizing the characteristics of a curve flow field, large impurities are subjected to pre-separation treatment through centrifugal force generated by airflow steering, the service cycle and the service life of the fine filtration unit can be prolonged, the cleaning frequency can be reduced, and the blocking cycle can be prolonged.

The utility model relates to the field of gas-water separation, in particular to a gas-water separation system for underground coal gasification. Comprising a product well, a synthesis gas washing assembly communicated with a gas outlet of the product well, a gas-water separation treatment assembly communicated with a liquid outlet of the synthesis gas washing assembly, a torch device communicated with a gas outlet of the gas-water separation treatment assembly, and a storage tank assembly communicated with a liquid outlet of the gas-water separation treatment assembly. According to the utility model, the combustible waste gas released in the gas-water separation process is safely combusted by using the torch device, so that atmospheric pollution caused by direct emission of the combustible waste gas is avoided; acid gas, phenols and ammonia nitrogen in the coal gas water are deeply removed through the phenol and ammonia recovery assembly, resource recovery of phenolic substances and liquid ammonia is achieved, meanwhile, purified wastewater can be reused for a chilling water circulating pump and conveyed to a product well or discharged after reaching the standard, the cyclic utilization rate of water resources is greatly increased, and the energy consumption is reduced. Therefore, the fresh water consumption and the wastewater treatment cost are obviously reduced.

The invention discloses a coal underground gasification strengthening method which comprises the following steps: step 1, drilling a U-shaped well of which the horizontal section is positioned in a coal seam at a target coal seam, respectively arranging an injection well and a production well at two ends of the U-shaped well, and putting a multi-channel continuous pipe into the horizontal section through the injection well; 2, oxygen, fuel and an ignition agent are injected into the horizontal section through the multi-channel continuous pipe to ignite the coal seam, then oxygen and a gasification agent are continuously injected through the multi-channel continuous pipe to enable the coal seam to be gasified to generate raw gas, and a gasification cavity is formed in the coal seam in the gasification process; 3, fuel and oxygen are injected into the newly-formed gasification cavity through the multi-channel continuous pipe, combustible gas cloud is formed at an outlet by the fuel and the oxygen, then the combustible gas cloud is ignited through an ignition agent sprayed out of the multi-channel continuous pipe for deflagration, and raw gas is produced; step 4; repeating the step 3 until the gasification of the cavity body of the gasification cavity is completed; and 5, the multi-channel continuous pipe is dragged to retreat, the steps 2-4 are repeated till gasification transformation of the whole coal seam is completed, and the gasification efficiency is high.

The application provides an underground gasification and electrolysis water coupling zero-carbon hydrogen production system and a resource comprehensive utilization method, which can effectively reduce the production cost of electrolytic hydrogen production, make full use of oxygen generated by electrolysis while providing suitable water sources, and make hydrogen energy more widely and practically applied; carbon monoxide produced by underground coal gasification and separated and purified is used as a circulating medium in the process of electrolytic hydrogen production, which can reduce a part of hydrogen production power consumption, and carbon dioxide and oxygen generated by the anode of the electrolytic cell can be used as a gasification agent in the gasification process or a combustion-supporting agent in the power generation process, and the carbon dioxide produced by the power generation device can also be injected into the underground gasification furnace as a gasification agent; while reducing the cost of high-purity gasification agent preparation and transportation, the condensate water of the synthesis gas after treatment can be reasonably utilized, and then the underground coal gasification technology and the existing electrolytic water hydrogen production process are combined to create a new zero-carbon hydrogen production system with a fusion of technical systems and efficient utilization of resources.

The invention relates to the technical field of coal underground gasification, and discloses a radioactive isotope-based coal underground gasification combustion space shape measurement method, which specifically comprises the following steps of: selecting and injecting radioactive isotopes: selecting the radioactive isotopes with moderate half-life period and injecting the radioactive isotopes into a combustion space; radiation detectors are arranged and data are collected, wherein the detectors are arranged on the basis of the periphery of a combustion space area where radioactive isotopes are injected, and radiation intensity data are collected; data processing: performing background radiation deduction based on the acquired radiation intensity data, and selecting a proper threshold value for a calculation result by adopting a maximum entropy threshold value method; outputting a result, dividing the boundary of the combustion air area based on the calculated model parameter m and the determined threshold value, and outputting a three-dimensional contour surface diagram and contour surface diagrams in all directions of the combustion air area; the measurement method provided by the invention is high in industrial practicability, high in measurement precision and relatively simple and convenient to operate, and provides important technical support for large-scale application of a coal underground gasification technology.

The invention provides a method and device for evaluating a coal underground gasification selected area, and belongs to the technical field of coal underground gasification. The method comprises the steps that the thickness value and coal volatile components of an underground coal seam in the coal underground gasification selected area to be evaluated are obtained; calculating the product of the thickness value and the coal volatile component to obtain an evaluation index; under the condition that the evaluation index is greater than or equal to a third threshold value, the evaluation result of the to-be-evaluated coal underground gasification selection area is suitable for carrying out coal underground gasification; under the condition that the evaluation index is smaller than a third threshold value, the evaluation result of the to-be-evaluated coal underground gasification selected area is not suitable for coal underground gasification. The device comprises a data acquisition module, a product calculation module and an evaluation result output module. The method is simple and convenient to use, small in calculation amount and easy to understand and memorize.

The invention discloses a simulation test device and method for the integrity of an underground coal gasification string. The device mainly includes a load loading device, a test string, a temperature reduction device and a heating device. A tensile / compressive load is applied to the test string through the load loading device to test the strength of the test string; cooling circulating water is pumped into the outer wall of the test string through the temperature reduction device to adjust the temperature; the temperature inside the test string is adjusted through the heating device. The simulation test device and method for the integrity of the underground coal gasification string of the invention can simulate the change of the bearing capacity of the string under the ultra-high temperature environment of underground coal gasification, and can also simulate the change of the bearing capacity of the string for heavy oil fire flooding, providing a test evaluation means for the selection of oil casing in high-temperature wells. Through the invention, the change rules of the structural strength and sealing performance of the string under different downhole working conditions can be obtained, and effective string specifications and models can be selected according to the operating pressure and temperature range, effectively reducing the cost of coal gasification mining.