In-SITU large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane

Abstract

An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane is provided, which includes: constructing an injection well to the target coal seam and then constructing a horizontal well to divide the target coal seam into sections of coal; extracting coalbed methane; transforming the horizontal wells on both sides of the coal in the first section of coal into coal gasification production wells, and dividing them into intake and exhaust channels; constructing ventilation boreholes to form a “honeycomb shaped” gasifier, which ignites and gasifies to promote the production of combined gases from combustion; after the combustion of first section of coal is completed, continuing to construct the next section of coal and drill holes between adjacent horizontal wells to achieve continuous coal seam combustion and gasification. The method of the present disclosure can improve combustion efficiency and increase kerosene extraction efficiency.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese Application No. CN202410305034.5, filed on Mar. 18, 2024, entitled “IN-SITU LARGE-AREA DRILLING AND FURNACE CONSTRUCTION METHOD FOR COAL GASIFICATION AND CO-MINING OF KEROSENE AND / OR COALBED METHANE”. These contents are hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of coal mining, in particular to an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane.BACKGROUND

[0003] Underground coal gasification is a process of converting solid coal into gaseous fuel. Carbon dioxide oil recovery technology refers to the oil extraction technique of injecting carbon dioxide gas into oil-bearing coal seams to achieve the extraction of kerosene and improve its recovery rate. Efficient extraction of coalbed methane through pressure control involves horizontal pre-drilling and maintaining the stability of the borehole with water pressure, when the water pressure is lower than the air pressure, coalbed methane is slowly released. The technology of drilling and furnace construction for coal gasification and co-mining of kerosene (coalbed methane) refers to the process of cracking and displacing of oil-bearing coal seams (or extracting coal seams containing coalbed methane), and then reacting coal with gasification agents under high temperature and pressure conditions, ultimately producing combustible gases (such as hydrocarbons, carbon monoxide, etc.) and other valuable by-products (such as kerosene, coal tar, etc.). The technology of coal gasification and co-mining of kerosene (coalbed methane) through drilling and furnace construction has important economic and environmental benefits and is widely used in energy production and chemical industry.

[0004] There are some unresolved issues in the traditional methods of coal gasification and kerosene (coalbed methane) collection, including difficulty in controlling the combustion range of the gasifier, irregular combustion range, and insufficient combustion of the coal seam. These issues may lead to low utilization of coal seam energy and have a negative impact on the environment. In the process of exploring ways to improve the efficiency of coal gasification and kerosene (coalbed methane) mining, some researchers have proposed improved methods. For example, by improving combustion control, optimizing the arrangement of inlet and outlet holes, and increasing coal seam permeability, the shortcomings of traditional methods can be improved. However, these methods still face challenges such as low resource development and utilization rates, uneven coal seam combustion, and difficulty in achieving comprehensive coal seam combustion. Therefore, it is necessary to seek a new technology to solve these problems and improve the efficiency and sustainability of coal gasification and kerosene (coalbed methane) mining.SUMMARY

[0005] To address the shortcomings of the existing technology, the present disclosure provides an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane. By arranging construction processes, transforming layout, dividing coal seams, and constructing honeycomb shaped structures, the traditional method solves the problems of irregular combustion range, insufficient combustion of coal seams, and waste of resource development, achieving efficient co-mining of kerosene.

[0006] The present disclosure adopts the following technical solution:

[0007] An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane, applied to a single coal seam, including the following steps:

[0008] Step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal.

[0009] Step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO2 injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both an oil transportation well and a coalbed methane transportation well.

[0010] For the oil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation well.

[0011] For coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation well, and the coalbed methane is slowly released and collected through the coalbed methane transportation well.

[0012] Step 3, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells;

[0013] The “honeycomb briquette like” mentioned above refers to the overall layout structure of all ventilation boreholes in the coal gasification production process.

[0014] Step 4, after the combustion of the first section of coal is completed, carrying out a mining of a second section of coal in sequence according to step 2 and step 3 to achieve continuous combustion and gasification of the coal seam.

[0015] In the step 2, constructing the first horizontal well based on the position of the first section of coal and the injection well layout plan; arranging pipeline for cracking oil displacement-coalbed methane extraction systems inside the first horizontal well and the second horizontal well, respectively.

[0016] In the step 3, the ventilation borehole is perpendicular to the coal gasification production well and parallel to the coal seam of the first section of coal.

[0017] In the step 3, it further includes an ignition device, using the ignition device to ignite the input gasification agent in the coal gasification production well, and the high-temperature gas generated during the combustion process further promotes the gasification reaction inside the coal seam.

[0018] In the step 4, an exhaust channel of the gasifier in the first section of coal is used as an intake channel of the gasifier in the second section of coal, and a new constructed coal gasification production well in the second section of coal is used as an exhaust channel of the gasifier in the second section of coal.

[0019] An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane, applied to multiple coal seams, including the following steps:

[0020] Step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal.

[0021] Step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO2 injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both oil transportation wells and a coalbed methane transportation wells.

[0022] For an upperoil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation wells.

[0023] For an upper coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation wells, and the coalbed methane is slowly released and collected through the coalbed methane transportation wells.

[0024] Step 3, for lower coal seams that have been drained of oil or coalbed methane, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells.

[0025] Step 4, after the combustion of lower coal seams of the first section of coal is completed, constructing the coal gasification production well for a next section of coal, then constructing ventilation boreholes to construct another gasifier to achieve continuous combustion and gasification of the coal seam.

[0026] Step 5, after the oil-bearing coal seam in the second section of coal is performed oil displacement, repeating step 3 and step 4 to carry out the gasification of the coal seam.

[0027] Advantageous effects of the present disclosure are as below:

[0028] (1) The present disclosure proposes an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane. In this method, the in-situ large-area drilling and furnace construction for coal gasification and co-mining of kerosene (coalbed methane) technology can be adjusted and optimized according to different geological conditions and coal seam structures. By transforming the layout and construction location of fracturing / CO2 injection wells (coal gasification production wells), it is possible to adapt to different types, scales, and depths of coal seams. This flexibility makes the technology widely applicable and extensibility in various coal gasification and kerosene extraction projects.

[0029] (2) The present disclosure adopts hydraulic fracturing of coal seams and injection of carbon dioxide for oil displacement, utilizing pressure difference to extract coalbed methane, making the extraction of kerosene and coalbed methane more economical, and improving the extraction rate and ultimate recovery of hydrocarbons.

[0030] (3) The present disclosure adopts in-situ large-area drilling and furnace construction for coal gasification technology, by constructing ventilation boreholes between the fracturing / CO2 injection wells on both sides of the section coal, a honeycomb briquette like structure is formed, which can effectively promote the full combustion of the coal seam and make the combustion range more uniform and controllable. This structure can more effectively utilize coal resources and increase the output and energy conversion efficiency of coal gasification.

[0031] (4) Traditional coal gasification methods typically require a large amount of energy supply, while the present disclosure maximizes the utilization of coal resources within the coal seam for combustion and gasification, reducing dependence on external energy sources. Meanwhile, by increasing combustion efficiency and kerosene extraction efficiency, coal resources can also be utilized more effectively, achieving energy conservation and sustainable utilization.

[0032] (5) The method in the present disclosure achieves continuous combustion and gasification of coal seam by continuously constructing horizontal wells and vertical ventilation boreholes for different sections of coal. This continuous gasification and collection process can maximize the utilization of coal resources, improve production efficiency, and reduce system downtime.

[0033] (6) The method of the present disclosure optimizes the combustion and gasification processes of coal, enabling the coal to burn fully and reducing the generation of combustion residues and harmful emissions. In addition, compared with traditional horizontal drilling methods, the method of the present disclosure has less interference underground, reduces geological and environmental damage, and improves work safety.

[0034] In summary, the in-situ large-area drilling and furnace construction for coal gasification and co-mining of kerosene (coalbed methane) technology of the present disclosure has multiple advantageous technical effects, such as improving combustion efficiency, increasing kerosene extraction efficiency, improving operational flexibility, and saving energy resources. These effects will have a positive impact on the sustainable development and environmental friendliness of the coal gasification and kerosene extraction fields.BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 and FIG. 2 are schematic diagrams of the system layout of the present disclosure when the in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane is used in a single coal seam.

[0036] FIG. 3 is a schematic diagram of the system layout of the present disclosure when the in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane is used in multiple coal seams.

[0037] FIG. 4 is a schematic diagram showing the structure of a gasifier. Reference numbers in the drawings:

[0038] 1. target coal seam,

[0039] 2. pipeline for cracking oil displacement-coalbed methane extraction system,

[0040] 3. first horizontal well,

[0041] 4. second horizontal well,

[0042] 5. multi-well drilling site,

[0043] 6. coal gasification production well,

[0044] 7. ventilation borehole,

[0045] 8. underground coal gasification system pipeline,

[0046] 9. injection well,

[0047] 10. surface oil tank,

[0048] 11. gasifier.DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] In the description of this application, “ / ” means “or” unless otherwise stated. For example, A / B can mean either A or B.

[0051] In the description of this application, “and / or” is only an association relationship describing the associated object, indicating that there can be three kinds of relationships, for example, A and / or B, can mean: there is A alone, there is A and B simultaneously, and there is B alone.

[0052] In the present invention, the terms “first” and “second” are merely for the purpose of description, but cannot be understood as indicating or implying relative importance.

[0053] In order to overcome the problems of low combustion range control and low extraction efficiency of kerosene and / or coalbed methane in existing technologies, the present disclosure proposes an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane. This method is applicable to both single coal seam and multiple coal seams. The following provides detailed illustration of the application of this method in single coal seam and multiple coal seams in conjunction with Embodiment 1 and Embodiment 2, respectively.

[0054] The “injection well” mentioned in the present disclosure extends downward from the ground surface towards the target coal seam and enters the coal seam, and is connected to the horizontal well.

[0055] The first horizontal well and the second horizontal well mentioned in the present disclosure are divided into fracturing-CO2 injection well and oil transportation well during the coal seam oil displacement stage.

[0056] The first horizontal well and the second horizontal well mentioned in the present disclosure can be used as water pressure well and coalbed methane transportation well during the coalbed methane extraction stage.Embodiment 1

[0057] As shown in FIG. 1 and FIG. 2, an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane is provided, which is applied to a single coal seam, and includes the following steps:

[0058] Step 1, drilling an injection well on ground to a target coal seam 1, then constructing a horizontal well in the target coal seam 1, and dividing the target coal seam 1 into a plurality of sections of coal, with a certain spacing between adjacent sections of coal. The spacing between adjacent sections of coal are equal. Preferably, the spacing between adjacent sections of coal is the optimal furnace width for drilling underground coal gasification furnaces in specific geological conditions.

[0059] The specific steps are: planning the well construction plan, determining the layout of the injection well, determining the drilling positions and spacing of each section of coal, constructing multi-well drilling site 5 for subsequent operations.

[0060] Dividing the target coal seam into sections of coal with appropriate spacing. The division method is determined based on the on-site situation, usually considering factors such as the thickness, coal quality, and gas recovery effect of the target coal seam.

[0061] Selecting a suitable position on the surface of the target coal seam, drilling and constructing the injection well 9 until reaching the target coal seam 1. Drilling the injection well to the position of the target coal seam 1, and further constructing it to become a horizontal well extending in the horizontal direction. Drilling holes sequentially in the horizontal well until the corresponding section of coal is reached.

[0062] Through the above steps, the injection wells are drilled on the ground to the target coal seam, and the horizontal wells are constructed to divide oil or coalbed methane containing coal seams into sections of coal with appropriate spacing. This operational plan can provide basic conditions for subsequent hydraulic fracturing, injection of carbon dioxide, or extraction of coalbed methane, in order to achieve goals such as oil displacement, extraction of coalbed methane, and coal combustion gasification. Meanwhile, a reasonable division of coal sections and injection well layout plan can also improve gas production efficiency and operational convenience.

[0063] Step 2, constructing a first horizontal well in a first section of the coal on the position of the first section of coal and the injection well layout plan, wherein the first horizontal well 3 serves as both a fracturing-CO2 injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both oil transportation wells and coalbed methane transportation wells. Preferably, the arrangement of the first horizontal well and the second horizontal well should cover each section of coal to ensure that subsequent operations can be fully carried out. At the same time, pipeline for cracking oil displacement-coalbed methane extraction systems 2 are arranged inside the first horizontal well and the second horizontal well.

[0064] For the oil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing of the oil-bearing coal seam in the first section of coal, causing cracks to form and expand in the coal seam, thereby increasing its permeability and providing a pathway for subsequent oil displacement operations; followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tank 10 through the oil transportation wells. The injection of carbon dioxide can have multiple effects, including increasing coal seam permeability, dissolving oil in coal seams, and promoting oil displacement. With the injection of carbon dioxide, the kerosene in the coal seam will be expelled. The generated kerosene is transported to the surface oil tank 10 through the oil transportation wells on both sides. The surface oil tank 10 receives and stores kerosene expelled from coal seams. According to the needs, kerosene can be further processed, such as separating impurities, purifying, etc., to meet different application requirements.

[0065] For coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, and the ventilation boreholes arranged in the first section of coal are used for the extraction of coalbed methane and serve as release channels for coalbed methane. The first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes. When the water pressure is lower than the pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation well, and the coalbed methane is slowly released and collected through the coalbed methane transportation well.

[0066] For coal seams containing coalbed methane, the plurality of the ventilation boreholes in each section of the coal seam are arranged in a honeycomb shape by providing water pressure wells as extraction channels for coalbed methane; arranging several ventilation boreholes, injecting water, and using water pressure to maintain the stability of the ventilation boreholes. When the water pressure remains slightly above the pressure of the coalbed methane, slow pressure reduction gradually releases the coalbed methane, which is collected by the coalbed methane transportation well and output to surface facilities.

[0067] Through the above steps, cracking oil displacement or extracting coalbed methane from each section of coal is achieved. Through reasonable well layout and operation methods, it is possible to effectively expelled kerosene or coalbed methane from coal seams to the surface for storage and processing. The technical solution is helpful to promote the production efficiency of kerosene or coalbed methane in the upper coal seam and to improve the utilization rate of resources.

[0068] Step 3, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells 6, and constructing ventilation boreholes in the coal gasification production wells 6, wherein the ventilation boreholes are used for coal gasification, with the function of increasing the surface area of coal seam combustion and improving gasification efficiency. By arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier 11; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells.

[0069] In the horizontal wells on both sides of the coal in the first section, selecting suitable positions for transformation to become coal gasification production wells 6. This includes installing necessary equipment and underground coal gasification system pipelines 8 for subsequent gasifier operations.

[0070] In the transformed coal gasification production wells, ventilation boreholes 7 are constructed inside the coal seam section by drilling. The ventilation boreholes 7 are perpendicular to the coal gasification production wells 6 on both sides and parallel to the target coal seam 1. By arranging and controlling ventilation boreholes reasonably, the first section of coal forms a “honeycomb briquette like” structure. This structure provides sufficient gas supply, which can promote gasification reactions inside the coal seam, increase the surface area of coal seam combustion, and improve gasification efficiency.

[0071] Injecting an appropriate amount of gasification agent into the intake channel of the coal gasification production well. The gasification agent will fully react with the coal in the coal seam, producing high-temperature gas that promotes the combustion and gasification process of the coal seam.

[0072] Igniting the input gasification agent in the coal gasification production well through appropriate ignition devices. The combustion process will produce high-temperature gases, which will drive the gasification reaction inside the coal seam.

[0073] The gas (hydrocarbons, carbon monoxide, etc.) produced is transported to surface facilities through the exhaust channel of the coal gasification production well. This includes the construction of appropriate pipelines and pumping stations to ensure the smooth transportation of gas from the wellhead to the ground surface for liquefaction and storage.

[0074] Through the above steps, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and form a “honeycomb briquette like” structure by constructing ventilation boreholes to construct a gasifier 11. By inputting an appropriate amount of gasification agent and igniting it to promote coal seam combustion and gasification reaction, and the generated gas is transported to surface facilities. This operational plan can achieve efficient coal gasification and gas utilization, providing important support for energy production.

[0075] Step 4, after the combustion of the first section of coal is completed, constructing the coal gasification production wells for the next section of coal, and constructing ventilation boreholes between the coal gasification production wells of the next section of coal to form a “honeycomb briquette like” structure in the same way, achieving continuous combustion and gasification of the coal seam.

[0076] After the first section of coal is completely combusted, the position of the next section of coal is determined based on the geological conditions of the coal seam and the gasification plan. Usually it is the next section adjacent to the first section of coal.

[0077] A new coal gasification production well is constructed on the other side of the position of the next section of coal. This includes the operation of drilling injection wells and horizontal wells, repeating the step 1 above.

[0078] Drilling vertical ventilation boreholes are carried out between the coal gasification production wells of the next section of coal to form a “honeycomb briquette like” structure similar to the first section of coal, and a new gasifier 11 is constructed to maintain the continuity and stability of the gasification reaction.

[0079] The exhaust channel of the previous gasifier 11 has been transformed to the intake channel of the new gasifier 11, and the newly constructed coal gasification production well serves as the exhaust channel of the new gasifier 11.

[0080] In the intake channel of the next section of coal, input gasification agent and ignite the coal seam for combustion and gasification. The generated gas is transported to ground facilities through the exhaust channel, wherein the ground facilities include a preliminary purification device, a CO2 separation device, a methane separation device, and gas storage tanks.

[0081] After the section of coal is completely combusted, continue to construct the coal gasification production wells of the next section, and conduct vertical ventilation drilling between adjacent coal gasification production wells to achieve continuous combustion and gasification of coal seam. This process can be repeated until the predetermined mining target is reached or the coal seam is exhausted.

[0082] Through the above steps, continuous combustion and gasification of coal seams in different sections can be achieved. After one section of coal is completely combusted, the coal gasification production wells of the next section will be constructed, forming a “honeycomb briquette like” structure to achieve continuous combustion and gasification of the coal seams. This operational solution can improve the efficiency of coal resource utilization and provide sustainable support for energy development.

[0083] Furthermore, pipeline devices for transporting CO2 and kerosene (coalbed methane) are installed in both the injection wells and the coal gasification production wells mentioned above.

[0084] Furthermore, the ground source of CO2 is separated from the combined gas produced by underground coal gasification and injected into the fracturing / CO2 injection well by a compressor. The surface source of water is condensed from the combined gas produced by underground coal gasification and supplemented by the external environment.

[0085] Furthermore, the ventilation boreholes are constructed perpendicular to the coal gasification production wells on both sides and parallel to the coal seam, with the aim of forming a “honeycomb briquette like” structure in the coal section, which facilitates full combustion. The two coal gasification production wells, one is the intake channel for injecting gasification agent, and the other is the exhaust channel for outputting combined gas.

[0086] Furthermore, the gasifier 11 is composed of coal in the middle section and coal gasification production wells on both sides, and the “honeycomb briquette like” structure is a section of coal structure that contains multiple through holes after drilling the ventilation boreholes.

[0087] Furthermore, ventilation boreholes are usually carried out by specialized drilling machines or equipment, and the spacing and depth need to be designed and adjusted according to specific circumstances.Embodiment 2

[0088] As shown in FIG. 3, an in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane is provided, which is applied to multiple coal seams, and includes the following steps:

[0089] Step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal. The spacing between adjacent sections of coal are equal. Preferably, the spacing between adjacent sections of coal is the optimal furnace width for drilling underground coal gasification furnaces in specific geological conditions.

[0090] Planning the well construction plan, determining the layout of the injection well, determining the drilling positions and spacing of each section of coal, constructing multi-well drilling site 5 for subsequent operations.

[0091] Dividing the target coal seam into sections of coal with appropriate spacing. The division method is determined based on the on-site situation, usually considering factors such as the thickness, coal quality, and gas recovery effect of the target coal seam.

[0092] Selecting a suitable position on the surface of the target coal seam, drilling and constructing the injection well 9 until reaching the target coal seam. Drilling the injection well to the position of the target coal seam, and further constructing it to become a horizontal well extending in the horizontal direction. Drilling holes sequentially in the horizontal well until the corresponding section of coal is reached

[0093] The constructed horizontal wells are distributed in multiple layers. The first horizontal well 3 (fracturing-CO2 injection well or water pressure well) and the second horizontal well 4 (oil transportation well or coalbed methane transportation well) are located in the upperoil-bearing and gas-bearing coal seam, while the coal gasification production well 6 is located in the lower non oil- bearing and non gas-bearing coal seam. The first horizontal well 3, the second horizontal well 4, and the coal gasification production well 6 are basically overlapped and arranged at equal intervals in the horizontal projection. At the same time, there are pipeline for cracking oil displacement coalbed methane extraction system 2 and underground coal gasification system pipeline 8 in the well.

[0094] Through the above steps, the injection wells are drilled on the ground to the target coal seam, and the horizontal wells are constructed to divide oil or coalbed methane containing coal seams into sections of coal with appropriate spacing. This operational plan can provide basic conditions for subsequent hydraulic fracturing, injection of carbon dioxide, or extraction of coalbed methane, in order to achieve goals such as oil displacement, extraction of coalbed methane, and coal combustion gasification. Meanwhile, a reasonable division of coal sections and injection well layout plan can also improve gas production efficiency and operational convenience.

[0095] Step 2, for an upperoil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks 10 through the oil transportation wells.

[0096] For an upper coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation wells, and the coalbed methane is slowly released and collected through the coalbed methane transportation wells.

[0097] According to the geological conditions of the coal seam and the layout plan of the injection well, the first horizontal well 3 and the second horizontal well 4 are constructed. The layout of the first horizontal well and the second horizontal well cover each section of coal to ensure that subsequent operations can be fully carried out.

[0098] For the upper oil-bearing coal seam, the high-pressure liquid is injected into the upper oil-bearing coal seam through the first horizontal well 3 to generate and expand fractures in the coal seam, thereby increasing coal seam permeability and providing a pathway for subsequent oil displacement operations. After completing hydraulic fracturing, carbon dioxide is injected into the target coal seam 1 through the first horizontal well 3. The injection of carbon dioxide can have multiple effects, including increasing coal seam permeability, dissolving oil in coal seams, and promoting oil displacement.

[0099] Followed by injecting carbon dioxide for oil displacement, the kerosene in the upper coal seam will be expelled. and transporting the obtained kerosene to surface oil tank 10 through the oil transportation wells.

[0100] The surface oil tank 10 receives and stores kerosene expelled from coal seams. According to the needs, kerosene can be further processed, such as separating impurities, purifying, etc., to meet different application requirements.

[0101] For coal seams containing coalbed methane, the plurality of the ventilation boreholes in each section of the coal seam are arranged in a honeycomb shape by providing water pressure wells as extraction channels for coalbed methane;

[0102] Arranging several ventilation boreholes, injecting water, and using water pressure to maintain the stability of the ventilation boreholes. When the water pressure remains slightly above the pressure of the coalbed methane, slow pressure reduction gradually releases the coalbed methane, which is collected by the coalbed methane transportation well and output to surface facilities.

[0103] Through the above steps, cracking oil displacement or extracting coalbed methane from each section of the upper coal is achieved. Through reasonable well layout and operation methods, it is possible to effectively expelled kerosene or coalbed methane from coal seams to the surface for storage and processing. The technical solution is helpful to promote the production efficiency of kerosene or coalbed methane in the upper coal seam and to improve the utilization rate of resources.

[0104] Step 3, for the lower coal seam that have been drained of oil or coalbed methane, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier 11; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells.

[0105] Selecting the position of the first section of coal in the lower coal seam, and constructing coal gasification production wells 6 on both sides. This includes the transformation and pipeline layout of the injection well 9 and the horizontal well.

[0106] In the transformed coal gasification production wells in the lower coal seam, ventilation boreholes 7 are constructed inside the coal seam section by drilling. The ventilation boreholes 7 are perpendicular to the coal gasification production wells 6 on both sides and parallel to the target coal seam. By arranging and controlling ventilation boreholes reasonably, the first section of coal forms a “honeycomb briquette like” structure. This structure provides sufficient gas supply, which can promote gasification reactions inside the coal seam, increase the surface area of coal seam combustion, and improve gasification efficiency.

[0107] Injecting an appropriate amount of gasification agent into the intake channel of the coal gasification production well 6. The gasification agent will fully react with the coal in the coal seam, producing high-temperature gas that promotes the combustion and gasification process of the coal seam.

[0108] Igniting the input gasification agent in the coal gasification production well through an appropriate ignition device. The combustion process will produce high-temperature gases, which will drive the gasification reaction inside the coal seam. The gas (hydrocarbons, carbon monoxide, etc.) produced is transported to surface facilities through the exhaust channel of the coal gasification production well on the other side. This includes the construction of appropriate pipelines and pumping stations to ensure the smooth transportation of gas from the wellhead to the ground surface for liquefaction and storage.

[0109] Through the above steps, constructing the coal gasification production wells on both sides of the first section of coal in the lower coal seam, and form a “honeycomb briquette like” structure by constructing ventilation boreholes to construct a gasifier 11. By inputting an appropriate amount of gasification agent and igniting it to promote coal seam combustion and gasification reaction, and the generated gas is transported to surface facilities. This operational plan can achieve efficient coal gasification and gas utilization, providing important support for energy production.

[0110] Step 4, after the combustion of lower coal seam of the first section of coal is completed, constructing the coal gasification production well for a next section of coal, then constructing ventilation boreholes to construct another gasifier to achieve continuous combustion and gasification of the coal seam.

[0111] After the first section of coal is completely combusted, the position of the next section of coal is determined based on the geological conditions of the coal seam and the gasification plan. Usually it is the next section adjacent to the first section of coal.

[0112] A new coal gasification production well 6 is constructed on the other side of the position of the next section of coal. This includes the operation of drilling injection wells and horizontal wells, repeating the step 1 above.

[0113] Between the coal gasification production wells 6 in the next section, ventilation boreholes 7 are constructed to form a “honeycomb briquette like” structure similar to the first section of coal, in order to increase the surface area of the coal seam and provide more contact surfaces for combustion and gasification reactions.

[0114] The exhaust channel of the previous gasifier 11 has been transformed to the intake channel of the new gasifier 11, and the newly constructed coal gasification production well serves as the exhaust channel of the new gasifier 11. In the intake channel of the next section of coal, gasification agent are inputted and the coal seam is ignited for combustion and gasification. The generated gas is transported to ground facilities through the exhaust channel.

[0115] After the section of coal is completely combusted, continue to construct the coal gasification production wells of the next section, and conduct vertical ventilation drilling between adjacent coal gasification production wells to achieve continuous combustion and gasification of coal seam. This process can be repeated until the predetermined mining target is reached or the coal seam is exhausted.

[0116] The above step 4 is to form a “honeycomb briquette like” structure inside the coal seam by constructing coal gasification production wells and ventilation boreholes for the next section of coal after the first section of coal combustion is completed, in order to achieve continuous coal seam combustion and gasification. Through the above steps, each coal seam in each section generates a gasifier 11, which can improve the efficiency of coal mining and fully utilize coal resources.

[0117] Step 5, after the oil-bearing coal seam in the second section of coal is performed oil displacement, repeating step 3 and step 4 to carry out the gasification of the coal seam.

[0118] After oil displacement in the upper oil-bearing coal seam, repeat steps 3 and 4 to carry out coal gasification on the already displaced coal seam. This step fully utilizes the already mined coal seams, further improving the efficiency of energy resource utilization and extending the service life of the coal mine.

[0119] The parts not mentioned in the present disclosure can be implemented by taking existing technology for reference.

Claims

1. An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane, applied to a single coal seam, comprising the following steps:step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal;step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO2 injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both an oil transportation well and a coalbed methane transportation well; injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing of the oil-bearing coal seam in the first section of coal, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation well; for coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation well, and the coalbed methane is slowly released and collected through the coalbed methane transportation well;step 3, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells;step 4, after the combustion of the first section of coal is completed, carrying out a mining of a second section of coal in sequence according to step 2 and step 3 to achieve continuous combustion and gasification of the coal seam.

2. The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane according to claim 1, wherein in step 2, constructing the first horizontal well based on a position of the first section of coal and an injection well layout plan;arranging pipeline for cracking oil displacement-coalbed methane extraction systems inside the first horizontal well and the second horizontal well, respectively.

3. The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane according to claim 1, wherein in step 3, the ventilation boreholes are perpendicular to the coal gasification production well and parallel to the coal seam of the first section of coal.

4. The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane according to claim 1, wherein in step 3, it further comprises an ignition device; using the ignition device to ignite the input gasification agent in the coal gasification production well, and the high-temperature gas generated during the combustion process further promotes the gasification reaction inside the coal seam.

5. The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane according to claim 1, wherein in step 4, an exhaust channel of the gasifier in the first section of coal is used as an intake channel of the gasifier in the second section of coal, and a new constructed coal gasification production well in the second section of coal is used as an exhaust channel of the gasifier in the second section of coal.

6. An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and / or coalbed methane, applied to multiple coal seams, comprising the following steps:step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal;step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO2 injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both oil transportation wells and a coalbed methane transportation wells; for an upperoil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation wells; for an upper coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation wells, and the coalbed methane is slowly released and collected through the coalbed methane transportation wells;step 3, for lower coal seams that have been drained of oil or coalbed methane, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells;step 4, after the combustion of lower coal seams of the first section of coal is completed, constructing the coal gasification production well for a next section of coal, then constructing ventilation boreholes to construct another gasifier to achieve continuous combustion and gasification of the coal seam;step 5, after the oil-bearing coal seam in the second section of coal is performed oil displacement, repeating step 3 and step 4 to carry out the gasification of the coal seam.

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