CN117888862A - In-situ large-area drilling and empty-building furnace coal gasification and kerosene and/or coal bed gas simultaneous production method - Google Patents

Abstract

The invention discloses an in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed gas simultaneous mining method, and relates to the technical field of coal mining. The method specifically comprises the following steps: drilling an injection well on the ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into section coal; carrying out oil displacement in a hydraulic fracturing and carbon dioxide injection mode, or efficiently pumping coal bed gas through hydraulic control drilling; after the coal bed is driven or the coal bed gas is pumped, changing the horizontal wells on two sides of the first section coal into production wells, dividing the production wells into an air inlet channel and an air outlet channel, constructing ventilation holes to form a honeycomb briquette-shaped gasification furnace, and igniting and gasifying to promote the combined gas generated by combustion; and after the first section of coal is burnt, continuing to construct the next section of coal, and drilling holes between adjacent horizontal wells to realize continuous coal seam burning gasification. The method can improve combustion efficiency, increase kerosene collection efficiency, improve operation flexibility and save energy resources.

Description

In-situ large-area drilling and furnace construction for coal gasification and simultaneous mining of kerosene and/or coalbed methane

Technical Field

The invention relates to the technical field of coal mining, and in particular to an in-situ large-area drilling furnace-building coal gasification and kerosene and/or coalbed methane simultaneous mining method.

Background technique

Underground coal gasification is a process that converts solid coal into gaseous fuel; CO2 flooding technology refers to the injection of CO2 gas into oil-bearing coal seams to achieve the extraction of coal oil and improve the recovery rate of coal oil; coal bed methane pressure-controlled efficient extraction is to pre-drill horizontal holes and use water pressure to keep the borehole stable. When the water pressure is lower than the gas pressure, the coal bed methane is slowly released. Boiler-building coal gasification and coal oil (coal bed methane) co-extraction technology is to crack and drive oil from oil-bearing coal seams (or extract coal bed methane from coal seams), and then react coal with gasification agents under high temperature and high pressure conditions to finally produce combustible gases (such as hydrocarbons, carbon monoxide, etc.) and other valuable by-products (such as kerosene, coal tar, etc.). Boiler-building coal gasification and coal oil (coal bed methane) co-extraction technology has important economic and environmental benefits and is widely used in energy production and chemical industries.

There are still some issues to be solved in the traditional coal gasification and coal oil (coal bed methane) collection process, including the difficulty in controlling the combustion range of the gasifier, the irregular combustion range, and the inability to fully burn the coal seam. These problems may lead to low energy utilization of the coal seam and have a negative impact on the environment. In the process of exploring ways to improve the efficiency of coal gasification and coal oil (coal bed methane) collection, some researchers have proposed improved methods. For example, the shortcomings of traditional methods are improved by improving combustion control, optimizing the arrangement of inlet and outlet holes, and increasing the permeability of coal seams. However, these methods still face the difficulties of low resource development and utilization, uneven coal seam combustion, and difficulty in achieving comprehensive combustion of coal seams. Therefore, it is necessary to seek a new technology to solve these problems and improve the efficiency and sustainability of coal gasification and coal oil (coal bed methane) collection.

Summary of the invention

In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a method for in-situ large-area drilling and furnace building for coal gasification and simultaneous mining of kerosene and/or coalbed methane. By arranging construction procedures, changing the layout, dividing coal sections, and constructing a honeycomb coal-like structure, the problems existing in the traditional method such as irregular combustion range, inability to fully burn coal seams, and waste of resource development are solved, thereby achieving efficient simultaneous mining of kerosene.

In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an in-situ large-area drilling and furnace building coal gasification and kerosene and/or coalbed methane co-mining method, which is applied to a single coal seam, and the method comprises the following steps: step 1, drilling an injection well on the ground to the target coal seam, and then constructing a horizontal well in the target coal seam, and dividing the target coal seam into several sections of coal, and maintaining a certain distance between adjacent sections of coal.

Step 2: construct a first horizontal well in the first section of coal. The first horizontal well serves as both a fracturing- _CO2 injection well and a water pressure well. Second horizontal wells are set on both sides of the first horizontal well. The second horizontal wells serve as both an oil well and a coalbed methane well.

For the oil-bearing coal seams in the first section, high-pressure liquid is injected through the first horizontal well for hydraulic fracturing, followed by injection of carbon dioxide for oil recovery, and the resulting kerosene is transported to the surface oil tank through the oil well.

For the coal seams containing coalbed methane in the first section of coal, firstly, several ventilation boreholes for extracting coalbed methane are arranged in the first section of coal. The overall structure of the several ventilation boreholes is honeycomb-shaped. The first horizontal well is used as a water pressure well. The water pressure well uses water pressure to keep the ventilation borehole stable. When the water pressure is lower than the coalbed methane pressure, the second horizontal well is used as a coalbed methane transportation well. The coalbed methane is slowly released and collected through the coalbed methane transportation well.

Step three: convert the horizontal wells on both sides of the first section of coal into coal gasification production wells, and construct ventilation holes in the coal gasification production wells. By arranging the ventilation holes, the coal in the first section forms a "honeycomb coal-like" structure to construct a gasifier; input gasifying agent on one side of the coal gasification production well, ignite it for full combustion and gasification, and the generated gas is transported to the ground facilities from the other side of the coal gasification production well.

The above-mentioned "honeycomb briquettes" refers to the overall arrangement structure of all ventilation holes in the coal gasification production process.

Step 4: After the combustion of the coal in the first section is completed, the mining of the coal in the second section is carried out in accordance with steps 2 and 3 to achieve continuous coal seam combustion and gasification.

In the above-mentioned in-situ large-area drilling and furnace construction method for coal gasification and simultaneous mining of kerosene and/or coalbed methane, in step two, a first horizontal well is constructed according to the position of the coal in the first section and the wellbore layout plan; cracking oil recovery-coalbed methane extraction system pipelines are laid in both the first horizontal well and the second horizontal well.

In the above-mentioned in-situ large-area drilling and furnace building method for coal gasification and simultaneous mining of kerosene and/or coalbed methane, in step three, the ventilation drill hole is perpendicular to the coal gasification production well and parallel to the coal seam of the first section of coal.

The above-mentioned in-situ large-area drilling and furnace construction method for coal gasification and kerosene and/or coalbed methane co-production, in step three, also includes an ignition device, which is used to ignite the input gasification agent in the coal gasification production well. The high-temperature gas generated during the combustion process further promotes the gasification reaction inside the coal seam.

In the above-mentioned method of in-situ large-area drilling and furnace construction for coal gasification and simultaneous mining of kerosene and/or coalbed methane, in step four, the outlet channel of the coal-in-gasification furnace in the first section serves as the inlet channel of the coal-in-gasification furnace in the second section, and the newly constructed production well in the coal in the second section serves as the outlet channel of the coal-in-gasification furnace in the second section.

A method for in-situ large-area drilling and furnace construction for coal gasification and simultaneous mining of kerosene and/or coalbed methane is applicable to multiple coal seams. The method comprises the following steps: Step 1, drilling an injection well on the 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 coal sections, with a certain distance between adjacent coal sections.

Step 2: construct a first horizontal well in the first section of coal. The first horizontal well serves as both a fracturing- _CO2 injection well and a water pressure well. Second horizontal wells are set on both sides of the first horizontal well. The second horizontal wells serve as both an oil well and a coalbed methane well.

For the upper oil-bearing coal seams in the first section, high-pressure liquid is injected through the first horizontal well for hydraulic fracturing, followed by injection of carbon dioxide for oil recovery, and the resulting kerosene is transported to the surface oil tank through the oil well.

For the upper coal seams containing coalbed methane in the first section of coal, firstly, a number of ventilation boreholes for extracting coalbed methane are arranged in the first section of coal. The overall structure of the several ventilation boreholes is honeycomb-shaped. The first horizontal well is used as a water pressure well. The water pressure well uses water pressure to keep the ventilation borehole stable. When the water pressure is lower than the coalbed methane pressure, the second horizontal well is used as a coalbed methane transportation well. The coalbed methane is slowly released and collected through the coalbed methane transportation well.

Step three, for the lower coal seams after oil recovery or coalbed methane extraction, the horizontal wells on both sides of the first section coal are converted into coal gasification production wells, and ventilation boreholes are constructed in the coal gasification production wells. By arranging the ventilation boreholes, the lower coal seams of the first section coal form a "honeycomb coal-like" structure to construct a gasifier; gasification agent is input on one side of the coal gasification production well, ignited for full combustion and gasification, and the generated gas is transported to the ground facilities from the other side of the coal gasification production well.

Step 4: After the combustion of the lower coal seam of the first section is completed, a coal gasification production well for the next section of coal is constructed, ventilation holes are constructed, and a gasifier is constructed to achieve continuous coal seam combustion and gasification.

Step 5: After the oil-bearing coal seam in the second section is driven for oil, steps 3 and 4 are repeated to gasify the coal seam.

Compared with the prior art, the present invention brings the following beneficial technical effects: (1) The present invention proposes a method for in-situ large-area drilling and furnace construction for coal gasification and kerosene and/or coalbed methane simultaneous mining, in which the in-situ large-area drilling and furnace construction for coal gasification and kerosene (coalbed methane) simultaneous mining technology can be adjusted and optimized according to different geological conditions and coal seam structures. By changing the layout and construction location of the fracturing/ _CO2 injection wells (production wells), it can adapt to coal seams of different types, sizes and depths. This flexibility makes the technology widely applicable and scalable in various coal gasification and kerosene mining projects.

(2) The present invention uses hydraulic fracturing of coal seams and injection of carbon dioxide to drive oil, and utilizes pressure difference to extract coal bed methane, thereby making the extraction of kerosene and coal bed methane more economical and improving the extraction rate and final recovery rate of hydrocarbons.

(3) The present invention adopts the in-situ large-area drilling and furnace construction coal gasification technology. By constructing ventilation holes between the fracturing/ _CO2 injection wells on both sides of the coal section, a honeycomb coal 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 improve the output and energy conversion efficiency of coal gasification.

(4) Traditional coal gasification methods usually require a large amount of energy supply. The present invention maximizes the use of coal resources inside the coal seam for combustion and gasification, reducing dependence on external energy. At the same time, by increasing combustion efficiency and kerosene collection efficiency, coal resources can also be used more effectively, achieving energy conservation and sustainable utilization.

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

(6) The method of the present invention optimizes the coal combustion and gasification process, so that the coal can be fully burned, reducing the generation of combustion residues and harmful emissions. In addition, compared with the traditional horizontal drilling method, the method of the present invention has less interference with the underground, reduces damage to the geology and environment, and improves work safety.

In summary, the in-situ large-area drilling and furnace construction coal gasification and coal oil (coalbed methane) simultaneous mining technology of the present invention has multiple beneficial technical effects such as improving combustion efficiency, increasing coal oil collection efficiency, improving operation flexibility and saving energy resources. These effects will have a positive impact on the sustainable development and environmental friendliness of the coal gasification and coal oil collection fields.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 and Fig. 2 are schematic diagrams of the system arrangement of the method for in-situ large-scale drilling and furnace construction of a single coal seam for coal gasification and simultaneous mining of kerosene and/or coalbed methane according to the present invention.

3 is a schematic diagram of the system layout of the method for in-situ large-scale drilling and furnace construction of multiple coal seams for coal gasification and simultaneous mining of kerosene and/or coalbed methane according to the present invention.

In the figure: 1. Target coal seam, 2. Cracking oil recovery-coalbed methane extraction system pipeline, 3. First horizontal well, 4. Second horizontal well, 5. Multi-well drilling site, 6. Coal gasification production well, 7. Ventilation borehole, 8. Underground coal gasification system pipeline, 9. Injection well.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

In the description of this application, unless otherwise specified, "/" means "or", for example, A/B can mean A or B. "And/or" in this article is only a way to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

In the description of this application, words such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit differences. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

The technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

Based on the problems of combustion range control and low kerosene and/or coalbed methane collection efficiency in the prior art methods, the present invention proposes an in-situ large-area drilling and furnace building method for coal gasification and kerosene and/or coalbed methane simultaneous mining. The method is applicable to both a single coal seam and multiple coal seams. The application of the method in a single coal seam and multiple coal seams is described in detail below in combination with Example 1 and Example 2, respectively.

The "injection well" mentioned in the present invention extends downward from the ground toward the target coal seam and enters the coal seam and is connected with the horizontal well.

The first horizontal well and the second horizontal well mentioned in the present invention are divided into fracturing- _CO2 injection wells and oil transportation wells in the coal seam oil recovery stage.

The first horizontal well and the second horizontal well mentioned in the present invention can be used as wells for providing water pressure and transporting coalbed methane during the coalbed methane extraction stage.

Embodiment 1: As shown in FIG. 1 and FIG. 2, a method for in-situ large-area drilling and furnace construction for coal gasification and kerosene and/or coalbed methane co-mining is applied to a single coal seam, comprising the following steps: Step 1: drilling an injection well on the ground to the 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 coal sections, with a certain distance between adjacent coal sections, and the distance between adjacent coal sections is kept equal. Preferably, the distance between adjacent coal sections is the optimal furnace width of a drilling-type underground coal gasification furnace in a specific geological condition area.

The specific steps are: planning the well construction plan, determining the wellbore layout location, determining the drilling location and spacing of each section of coal, and constructing a multi-well drilling site 5 for subsequent operations.

The target coal seam is divided into sections with appropriate spacing. The division method is determined according to the on-site conditions, usually taking into account factors such as the thickness of the target coal seam, coal quality, and gas production effect.

Select a suitable location on the surface of the target coal seam and drill an injection well 9 until the target coal seam 1. The injection well is drilled to the target coal seam 1 and further constructed to become a horizontal well extending in the horizontal direction. Drill holes in the horizontal well in sequence until the corresponding section coal is reached.

Through the above steps, an injection well is drilled on the ground to the target coal seam, and a horizontal well is constructed to divide the oil-bearing or coal-bed methane-bearing coal seam into sections with appropriate spacing. Such an operation plan can provide basic conditions for subsequent hydraulic fracturing, carbon dioxide injection or coal-bed methane extraction operations to achieve goals such as oil displacement or coal-bed methane extraction and coal-bed combustion gasification. At the same time, a reasonable coal section division and wellbore layout plan can also improve gas production effects and operational convenience.

Step 2: According to the location of the coal sections and the wellbore layout plan, a first horizontal well is constructed in the first coal section. The first horizontal well 3 serves as both a fracturing- _CO2 injection well and a water pressure well. Second horizontal wells 4 are respectively set on both sides of the first horizontal well 3. The second horizontal wells serve as both oil wells and coalbed methane transportation wells. Preferably, the layout of the first horizontal well and the second horizontal well should cover each coal section to ensure that subsequent operations can be fully carried out. At the same time, cracking oil recovery-coalbed methane extraction system pipelines 2 are laid in the first horizontal well and the second horizontal well.

For the oil-bearing coal seams in the first section, high-pressure liquid is injected through the first horizontal well for hydraulic fracturing, so that cracks in the coal seams are generated and expanded to increase the permeability of the coal seams and provide channels for subsequent oil recovery operations; then carbon dioxide is injected for oil recovery, and the resulting kerosene is transported to the ground tank through the oil well; the injection of carbon dioxide can play multiple roles, including increasing the permeability of the coal seams, dissolving the oil in the coal seams, and promoting the oil recovery effect. With the injection of carbon dioxide, the kerosene in the coal seams will be pushed out. The generated kerosene is sent to the ground tank through the oil wells on both sides. The ground tank receives and stores the kerosene driven out of the coal seams. As needed, the kerosene can be further processed, such as separating impurities and purifying, to meet different application requirements.

For the coal seams containing coalbed methane in the first section of coal, firstly, several ventilation boreholes for extracting coalbed methane are arranged in the first section of coal. The overall structure of the several ventilation boreholes is honeycomb-shaped. The ventilation boreholes arranged in the first section of coal are used for extracting coalbed methane, and their function is a release channel for coalbed methane. The first horizontal well is used as a water pressure well, and the water pressure well uses water pressure to keep the ventilation borehole stable. When the water pressure is lower than the coalbed methane pressure, the second horizontal well is used as a transportation coalbed methane well, and the coalbed methane is slowly released and collected through the transportation coalbed methane well.

For coal seams containing coalbed methane, a number of ventilation boreholes in each section of the coal seam are arranged in a honeycomb shape by providing a water pressure well as a channel for extracting and releasing coalbed methane; a number of ventilation boreholes are arranged, water is injected, and the ventilation boreholes are kept stable by water pressure. When the water pressure is slightly higher than the coalbed methane pressure, the pressure is slowly reduced so that the coalbed methane is gradually released, collected by the coalbed methane transmission well and output to the ground facilities.

Through the above steps, the coal in each section is cracked to drive oil or extract coalbed methane. Through reasonable well layout and operation mode, the kerosene or coalbed methane in the coal seam can be effectively transported to the ground for storage and processing. This technical solution helps to improve the output efficiency of kerosene or coalbed methane in the upper coal seam and improve resource utilization.

Step three, convert the horizontal wells on both sides of the first section of coal into coal gasification production wells 6, and construct ventilation holes in the coal gasification production wells 6. The ventilation holes are used for coal gasification, and their function is to increase the surface area of coal seam combustion and improve gasification efficiency. By arranging the ventilation holes, the coal in the first section forms a "honeycomb coal-like" structure to construct a gasifier; input gasifier on one side of the coal gasification production well, ignite it for full combustion and gasification, and the generated gas is transported to the ground facilities from the other side of the coal gasification production well.

In the horizontal wells on both sides of the coal in the first section, appropriate locations are selected for transformation to make them coal gasification production wells 6. This includes installing necessary equipment and underground coal gasification system pipelines 8 for subsequent gasifier operation.

In the transformed production well, ventilation holes 7 are constructed inside the coal seam section by drilling. The ventilation holes 7 are perpendicular to the coal gasification production wells 6 on both sides and parallel to the target coal seam 1. Through reasonable ventilation hole arrangement and control, the coal in the first section forms a "honeycomb coal-like" structure. Such a structure provides sufficient gas supply, which can promote the gasification reaction inside the coal seam, increase the surface area of coal seam combustion, and improve gasification efficiency.

An appropriate amount of gasifying agent is input into the gas inlet channel of the coal gasification production well. The gasifying agent will fully react with the coal in the coal seam to produce high-temperature gas, which will promote the combustion and gasification process of the coal seam.

The gasification agent is ignited in the coal gasification production well through appropriate ignition devices. The combustion process will produce high-temperature gas to promote the gasification reaction inside the coal seam.

The gas (hydrocarbons, carbon monoxide, etc.) produced is transported to ground facilities through the outlet channel of the coal gasification production well. This includes the construction of appropriate pipelines and pumping stations and other equipment to ensure that the gas can be smoothly transported from the wellhead to the ground for liquefied storage.

Through the above steps, the horizontal wells on both sides of the coal in the first section are transformed into coal gasification production wells, and a "honeycomb coal-like" structure is formed by constructing ventilation holes to construct a gasifier. An appropriate amount of gasifier is input and ignited to promote coal seam combustion and gasification reactions, and the generated gas is transported to ground facilities. Such an operation plan can achieve efficient coal gasification and gas utilization, providing important support for energy production.

Step 4: After the first section of coal is burned, the production wells for the next section of coal are constructed, and ventilation holes are drilled between the production wells for the next section of coal to form a "honeycomb coal-like" structure in the same way to achieve continuous coal seam combustion and gasification.

After the first section of coal is burned, the location of the next section of coal is determined based on the coal seam geological conditions and gasification plan, usually the next section adjacent to the first section of coal.

On the other side of the next section coal position, a new production well is constructed. This includes drilling injection wells and horizontal wells, repeating the above step 1.

Between the production wells of the coal in the next section, vertical ventilation drilling operations are carried out to form a "honeycomb coal-like" structure similar to that of the first section, and a new gasifier is constructed to maintain the continuity and stability of the gasification reaction.

The gas outlet channel of the previous gasifier is changed to the gas inlet channel of the new gasifier, and the newly constructed production well is used as the gas outlet channel of the new gasifier.

In the gas inlet channel of the next section coal, the gasifying agent is input and the coal seam is ignited for combustion and gasification. The generated gas is transported to the ground facilities through the gas outlet channel. The ground facilities include the primary purification device, _CO2 separation device, methane separation device and gas storage tank.

When the coal in a section is burned, the production well of the next section will be constructed, and vertical ventilation holes will be drilled between adjacent production wells to achieve continuous coal seam combustion and gasification. This process can be repeated until the predetermined mining target is reached or the coal seam is exhausted.

Through the above steps, continuous combustion and gasification of coal seams in different sections can be achieved. After the combustion of one section is completed, the production well of the next section will be constructed, and a "honeycomb coal-like" structure will be formed to achieve continuous combustion and gasification of coal seams. Such an operation plan can improve the utilization efficiency of coal resources and provide sustainable support for energy development.

Furthermore, in the above-mentioned injection wells and production wells, pipeline devices for transporting _CO2 and kerosene (coalbed methane) are laid.

Furthermore, the surface source of CO ₂ is separated from the combined gas produced by underground coal gasification and injected into the fracturing/CO ₂ 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 outside.

Furthermore, the ventilation holes are drilled perpendicular to the production wells on both sides and parallel to the coal seam, in order to form a "honeycomb-like" structure of the coal in the section, which is conducive to full combustion. The production well has one air inlet channel for injecting gasifying agent and the other for outputting the combined gas outlet channel.

Furthermore, the gasifier is composed of the middle section coal and the production wells on both sides; the "honeycomb coal-like" structure is a section coal structure containing multiple through-holes after the ventilation holes are drilled.

Furthermore, ventilation drilling is usually carried out by a special drilling machine or equipment, and the spacing and depth thereof need to be designed and adjusted according to specific circumstances.

Embodiment 2: As shown in FIG3, a method for in-situ large-area drilling and furnace construction for coal gasification and coal oil and/or coalbed methane co-mining is applied to multiple coal seams, comprising the following steps: Step 1, drilling an injection well on the ground to the target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of coal sections, with a certain distance between adjacent coal sections; the distance between adjacent coal sections is kept equal. Preferably, the distance between adjacent coal sections is the optimal furnace width of a drilling-type underground coal gasification furnace in an area with specific geological conditions.

Plan the well construction plan, determine the wellbore layout, determine the drilling location and spacing of each section of coal, and construct a multi-well drilling site 5 for subsequent operations.

The target coal seam 1 is divided into sections of coal with appropriate spacing. The division method is determined according to the on-site conditions, usually taking into account factors such as the thickness of the target coal seam, coal quality, and gas production effect.

Select a suitable location on the surface of the target coal seam and drill an injection well 9 until the target coal seam is reached. The injection well is drilled to the coal seam and further constructed to become a horizontal well extending in the horizontal direction. Drilling operations are performed in the horizontal well in sequence until the corresponding section coal is reached.

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 transmission well or coalbed methane transmission well) are located in the upper layer of oil-bearing and gas-bearing coal seams, and the coal gasification production well 6 is located in the lower layer of non-oil-bearing and non-gas-bearing coal seams. The first horizontal well 3 and the second horizontal well 4 are basically overlapped with the production well 6 in horizontal projection and are arranged at equal intervals. At the same time, the cracking oil-coalbed methane extraction system pipeline 2 and the underground coal gasification system pipeline 8 are laid in the well.

Through the above steps, injection wells are drilled on the ground to the coal seam, and horizontal wells are constructed to divide the oil-bearing coal seam into sections with appropriate spacing. Such an operation plan can provide basic conditions for subsequent operations such as carbon dioxide injection and coal gasification to achieve goals such as oil recovery and coal seam combustion gasification. At the same time, reasonable section coal division and wellbore layout plans can also improve oil recovery, gas recovery effects and operational convenience.

Step 2: For the upper oil-bearing coal seam in the first section, high-pressure liquid is injected through the first horizontal well to perform hydraulic fracturing, followed by injection of carbon dioxide for oil recovery, and the resulting kerosene is transported to the surface oil tank through the oil well.

For the upper coal seams containing coalbed methane in the first section of coal, firstly, a number of ventilation boreholes for extracting coalbed methane are arranged in the first section of coal. The overall structure of the several ventilation boreholes is honeycomb-shaped. The first horizontal well is used as a water pressure well. The water pressure well uses water pressure to keep the ventilation borehole stable. When the water pressure is lower than the coalbed methane pressure, the second horizontal well is used as a coalbed methane transportation well. The coalbed methane is slowly released and collected through the coalbed methane transportation well.

According to the geological conditions of the coal seam and the wellbore layout plan, 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 covers the coal in each section to ensure that subsequent operations can be fully carried out.

For the upper oil-bearing coal seam, high-pressure liquid is injected through the first horizontal well 3 to generate and expand cracks in the coal seam to increase the permeability of the coal seam and provide a channel for subsequent oil recovery operations. After the hydraulic fracturing is completed, carbon dioxide is injected into the target coal seam 1 through the first horizontal well 3. The injection of carbon dioxide can play multiple roles, including increasing the permeability of the coal seam, dissolving the oil in the coal seam, and promoting the oil recovery effect.

With the injection of carbon dioxide, kerosene in the upper coal seam will be pushed out. The produced kerosene is transported to the surface oil tank through the second horizontal well 4.

The surface tank receives and stores kerosene driven from the upper coal seams. Kerosene can be further processed as needed, such as separating impurities and purifying to meet different application requirements.

For coal seams containing coalbed methane, hydraulic wells are provided to arrange ventilation holes in each section of the coal seam into a honeycomb shape, which serves as a channel for extracting and releasing coalbed methane.

The ventilation boreholes for coal-bed methane extraction are laid out, water is injected, and the water pressure is used to keep the ventilation boreholes stable. The water pressure is kept slightly higher than the coal-bed methane pressure, and the pressure is slowly reduced to gradually release the coal-bed methane, which is collected by the coal-bed methane transmission well and output to the surface facilities.

Through the above steps, the coal in each section of the upper coal seam is cracked to drive oil or extract coalbed methane. Through reasonable well layout and operation mode, the kerosene or coalbed methane in the coal seam can be effectively promoted to be transported to the ground, stored and processed. This technical solution helps to improve the output efficiency of kerosene or coalbed methane in the upper coal seam and improve resource utilization.

Step three, for the lower coal seams after oil recovery or coalbed methane extraction, the horizontal wells on both sides of the first section coal are converted into coal gasification production wells, and ventilation boreholes are constructed in the coal gasification production wells. By arranging the ventilation boreholes, the lower coal seams of the first section coal form a "honeycomb coal-like" structure to construct a gasifier; gasification agent is input on one side of the coal gasification production well, ignited for full combustion and gasification, and the generated gas is transported to the ground facilities from the other side of the coal gasification production well.

In the lower stratum coal seam, the location of the first section coal is selected, and the coal gasification production wells 6 on both sides are constructed. This includes operations such as the transformation of the injection well 9 and the horizontal well and the arrangement of pipelines.

In the coal gasification production well that has been transformed in the lower layer, ventilation holes 7 are constructed inside the coal seam in the section by drilling. The ventilation holes are perpendicular to the coal gasification production wells on both sides and parallel to the coal seam. Through the reasonable arrangement and control of the ventilation holes, the coal in the first section forms a "honeycomb coal-like" structure. Such a structure provides sufficient gas supply, which can promote the gasification reaction inside the coal seam, increase the surface area of the coal seam combustion, and improve the gasification efficiency.

An appropriate amount of gasifying agent is input into the gas inlet channel of the coal gasification production well 6. The gasifying agent will fully react with the coal in the coal seam to generate high-temperature gas, which promotes the combustion and gasification process of the coal seam.

The gasification agent is ignited in the coal gasification production well through appropriate ignition devices. The combustion process will produce high-temperature gas to promote the gasification reaction inside the coal seam. The generated gas (hydrocarbons, carbon monoxide, etc.) is transported to the ground facilities through the gas outlet channel of the coal gasification production well 6 on the other side. This includes the construction of appropriate pipelines and pumping stations and other equipment to ensure that the gas can be smoothly transported from the wellhead to the ground for liquefied storage.

Through the above steps, the coal gasification production wells on both sides of the first section of the lower coal seam are constructed, and a "honeycomb coal-like" structure is formed by constructing ventilation holes to construct a gasifier. An appropriate amount of gasifier is input and ignited to promote the combustion and gasification reaction of the coal seam, and the generated gas is transported to the ground facilities. Such an operation plan can achieve efficient coal gasification and gas utilization in the lower coal seam, providing sustainable support for energy production.

Step 4: After the combustion of the lower coal seam of the first section is completed, a production well for the next section of coal is constructed, ventilation holes are constructed, and a gasifier is constructed to achieve continuous coal seam combustion and gasification.

After the first section of coal is burned, the location of the next section of coal is determined based on the coal seam geological conditions and gasification plan, usually the next section adjacent to the first section of coal.

On the other side of the next section coal position, a new coal gasification production well 6 is constructed. This includes the operation of drilling an injection well and a horizontal well, and repeating the above step 1.

Between the coal gasification production wells 6 of the next section of coal, ventilation boreholes 7 are constructed to form a "honeycomb coal-like" structure similar to that of the first section to increase the surface area of the coal seam and provide more contact surfaces for combustion and gasification reactions.

The gas outlet channel of the previous gasifier is changed to the gas inlet channel of the new gasifier, and the newly constructed coal gasification production well is used as the gas outlet channel of the new gasifier. In the coal inlet channel of the next section, the gasifying agent is input and the coal seam is ignited for combustion and gasification. The generated gas is transported to the ground facilities through the gas outlet channel.

When the coal in a section is burned, the coal gasification production well of the next section will be constructed, and vertical ventilation drilling will be carried out between adjacent coal gasification production wells to achieve continuous coal seam combustion and gasification. This process can be repeated until the predetermined mining target is reached or the coal seam is exhausted.

The fourth step is to form a "honeycomb coal-like" structure inside the coal seam by constructing a production well and ventilation borehole for the next section of coal after the first section of coal is burned, so as to achieve continuous coal seam combustion and gasification. Through the above steps, each section of the coal seam generates a gasifier, which can improve the efficiency of coal mining and make full use of coal resources.

Step 5: After the oil-bearing coal seam in the second section is driven for oil, steps 3 and 4 are repeated to gasify the coal seam.

After the upper oil-bearing coal seam is flooded, steps 3 and 4 are repeated to gasify the flooded coal seam. This step makes full use of the mined coal seam, further improves the utilization efficiency of energy resources, and prolongs the service life of the coal mine.

Parts not described in the present invention can be implemented by referring to the existing technology.

It should be noted that any equivalent method or obvious variation made by those skilled in the art under the guidance of this specification should be within the protection scope of the present invention.

Claims (6)

1. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed gas simultaneous production method is applied to a single coal bed and is characterized by comprising the following steps of:

drilling an injection well on the ground to a target coal seam, then constructing a horizontal well in the target coal seam, dividing the target coal seam into a plurality of section coals, and keeping a certain distance between the adjacent section coals;

step two, constructing a first horizontal well in the first section of coal, wherein the first horizontal well is used as fracturing-CO injection ₂ The well is also used as a water-pressure well, two sides of the first level are respectively provided with a second horizontal well, and the second horizontal well is used as a conveying oil well and a coal bed gas well;

injecting high-pressure liquid into an oil-containing coal bed in the first section of coal through a first horizontal well to perform hydraulic fracturing, then injecting carbon dioxide to perform oil displacement, and conveying the obtained kerosene into a ground oil tank through an oil conveying well;

for a coalbed methane-containing coal bed in the first section coal, arranging a plurality of ventilation holes for pumping and draining the coalbed methane in the first section coal, wherein the whole structure of the ventilation holes is honeycomb, a first horizontal well is used as a hydraulic well, the hydraulic well is kept stable by the hydraulic pressure, when the hydraulic pressure is lower than the coalbed methane pressure, a second horizontal well is used as a conveying coalbed methane well, and the coalbed methane is slowly released and collected by the conveying coalbed methane well;

step three, changing horizontal wells on two sides of the first section coal into coal gasification production wells, constructing ventilation drilling holes in the coal gasification production wells, arranging the ventilation drilling holes to enable the first section coal to form a honeycomb coal-shaped structure, and constructing a gasification furnace; inputting gasifying agent at one side of a coal gasification production well, igniting and fully burning and gasifying, and conveying generated gas to ground facilities from the other side of the coal gasification production well;

and fourthly, after the first section of coal is burnt, the second section of coal is mined according to the second and third construction steps in sequence, so that continuous coal seam burning and gasification are realized.

2. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed methane simultaneous production method as claimed in claim 1, wherein the method comprises the following steps: step two, constructing a first horizontal well according to the position of the first section coal and a shaft arrangement scheme; and pipelines of a cracking oil displacement-coal bed gas pumping system are paved in the first horizontal well and the second horizontal well.

3. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed methane simultaneous production method as claimed in claim 1, wherein the method comprises the following steps: in the third step, the ventilation drilling holes are vertical to the coal gasification production well and parallel to the coal bed of the first section of coal.

4. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed methane simultaneous production method as claimed in claim 1, wherein the method comprises the following steps: and thirdly, an ignition device is further included, the ignition device is utilized to ignite the input gasifying agent in the coal gasification production well, and high-temperature gas generated in the combustion process further pushes gasification reaction in the coal bed to proceed.

5. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed methane simultaneous production method as claimed in claim 1, wherein the method comprises the following steps: in the fourth step, the gas outlet channel of the gasifier in the first section of coal is used as the gas inlet channel of the gasifier in the second section of coal, and the newly constructed production well in the second section of coal is used as the gas outlet channel of the gasifier in the second section of coal.

6. The in-situ large-area drilling and emptying furnace coal gasification and kerosene and/or coal bed gas simultaneous production method is applied to multiple coal beds and is characterized by comprising the following steps of:

drilling an injection well on the ground to a target coal seam, then constructing a horizontal well in the target coal seam, dividing the target coal seam into a plurality of section coals, and keeping a certain distance between the adjacent section coals;

step two, constructing a first horizontal well in the first section of coal, wherein the first horizontal well is used as fracturing-CO injection ₂ The well is also used as a water-pressure well, two sides of the first level are respectively provided with a second horizontal well, and the second horizontal well is used as a conveying oil well and a coal bed gas well;

injecting high-pressure liquid into an upper layer oil-containing coal bed in the first section of coal through a first horizontal well to perform hydraulic fracturing, then injecting carbon dioxide to perform oil displacement, and conveying the obtained kerosene into a ground oil tank through an oil conveying well;

for the upper layer coal bed methane-containing coal bed in the first section coal, arranging a plurality of ventilation holes for pumping and discharging the coal bed methane in the first section coal, wherein the whole structure of the ventilation holes is honeycomb, taking a first horizontal well as a hydraulic well, keeping the ventilation holes stable by water pressure, taking a second horizontal well as a conveying coal bed gas well when the water pressure is lower than the coal bed methane pressure, and slowly releasing the coal bed methane and collecting the coal bed methane by the conveying coal bed gas well;

step three, for the lower layer coal bed after oil displacement or coal bed gas drainage, changing the horizontal wells on two sides of the first section coal into coal gasification production wells, constructing ventilation drilling holes in the coal gasification production wells, and arranging the ventilation drilling holes to enable the lower layer coal bed of the first section coal to form a honeycomb coal-shaped structure to construct a gasification furnace; inputting gasifying agent at one side of a coal gasification production well, igniting and fully burning and gasifying, and conveying generated gas to ground facilities from the other side of the coal gasification production well;

step four, after the combustion of the lower layer coal bed of the first section of coal is completed, constructing a coal gasification production well of the next section of coal, constructing ventilation holes, constructing a gasification furnace, and realizing continuous coal bed combustion and gasification;

and fifthly, repeating the third and fourth steps after the oil displacement of the oil-containing coal bed of the second section of coal, and gasifying the coal in the coal bed.