A system and method for producing oil and gas products from in situ coal pyrolysis underground

Abstract

The present application belongs to the technical field of coal in-situ pyrolysis, and specifically discloses a coal underground in-situ pyrolysis oil and gas product extraction system and method. The system comprises an extraction well, a plurality of injection wells are evenly arranged around the extraction well, the bottom of each injection well is connected to the bottom of the extraction well through an inclined shaft, the depth of the extraction well is greater than the depth of the injection well, an extraction module is arranged in the extraction well, the extraction module is used for collecting gaseous products and liquid products in the extraction well, the gas outlet of the extraction module is connected to the gas inlet of a gaseous product separation module, the gas outlet of the gaseous product separation module is connected to the injection well, and the outlet of the extraction module is connected to the inlet of a liquid product separation module. Since the depth of the extraction well is greater than the depth of the injection well, the height difference causes the products to gather in the extraction well, and then the gaseous products and the liquid products are sent into the separation module for separation, so that the pyrolysis gas and heat are fully utilized, the collection difficulty is greatly reduced, the extraction rate is higher, and the energy utilization rate is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of coal in-situ pyrolysis technology, specifically relating to a system and method for extracting oil and gas products from underground coal in-situ pyrolysis. Background Technology

[0002] Defects and shortcomings of existing technology:

[0003] The main products of underground in-situ coal pyrolysis are tar and pyrolysis gas. Existing underground oil and gas extraction technologies primarily utilize superheated nitrogen, carbon dioxide, and other high-temperature carrier gases to purge the oil and gas products generated from coal pyrolysis through the production well and carry them to the surface, where they are then cooled, separated, and purified. However, the pyrolysis products include both gaseous products like pyrolysis gas and liquid products like tar and water. Furthermore, a significant portion of the tar produced by pyrolysis is high-boiling-point bitumen. Therefore, the extraction process must ensure the smooth extraction of gaseous products while maintaining good insulation of the production well to guarantee efficient extraction of liquid products, resulting in high energy consumption and demanding technological requirements. In addition, underground coal seams are often heterogeneous, frequently containing interlayers of gangue, further increasing the requirements for extraction equipment. Currently, there is no suitable method for extracting oil and gas products from underground in-situ coal pyrolysis. Moreover, existing underground well layout methods mainly involve setting up horizontal wells along the formation, which, due to the high viscosity and poor fluidity of tar, result in low recovery rates. Summary of the Invention

[0004] The purpose of this invention is to provide a system and method for extracting oil and gas products from underground in-situ pyrolysis of coal, so as to solve the technical problems of difficult product extraction, difficult tar collection, and high requirements for heat preservation measures in the production well during existing underground in-situ pyrolysis of coal.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention provides an oil and gas product extraction system for underground in-situ pyrolysis of coal, comprising an extraction well, a plurality of injection wells uniformly arranged around the extraction well, the bottom of each injection well being connected to the bottom of the extraction well via an inclined shaft, the depth of the extraction well being greater than the depth of the injection wells, an extraction module being provided inside the extraction well, the extraction module being used to extract gaseous and liquid products from the extraction well, the gas outlet of the extraction module being connected to the gas inlet of a gas phase product separation module, the gas outlet of the gas phase product separation module being connected to the plurality of injection wells respectively, and the outlet of the extraction module being connected to the inlet of a liquid phase product separation module.

[0007] A further improvement of the present invention is that: the production module includes a second casing, which is installed inside the production well. The bottom sidewall of the second casing has several first through holes, each of which is connected to an inclined pipe. The second casing contains a first casing, and the first casing contains an oil cylinder. The oil cylinder contains a first oil pipe, and the bottom of the oil cylinder has a one-way valve. A first space is formed between the first casing and the second casing, and a second space is formed between the first casing and the oil cylinder. The first oil pipe is equipped with a gas lift valve. The gas outlet of the first space is connected to the gas inlet of the gas phase product separation module. The second space is filled with a heat-insulating medium. The gas inlet of the oil cylinder is connected to the gas outlet of the lifting gas supply module. The outlet of the first oil pipe is connected to the inlet of the liquid phase product separation module.

[0008] A further improvement of the present invention is that: the production module includes a third sleeve, which is installed inside the production well; a second through hole is provided on the bottom side wall of the third sleeve, which is connected to an inclined pipe; a fourth sleeve is provided inside the third sleeve; a fifth sleeve is provided inside the fourth sleeve; a second oil pipe is provided inside the fifth sleeve; a third space is formed between the third sleeve and the fourth sleeve; the air outlet of the third space is connected to the air inlet of the gas phase product separation module; a fourth space is formed between the fourth sleeve and the fifth sleeve; the fourth space is filled with a heat-insulating medium; and from bottom to top, the second oil pipe is provided with a plug, a screen pipe, an oil pump, a solid sucker rod, a hollow joint, and a hollow sucker rod.

[0009] A further improvement of the present invention is that: the gas phase product separation module includes a cyclone separator, a heat exchanger, a condensation separation device, a gas separation device, a CO2 capture device, a CO2 collection device, and a heating furnace. The inlet of the cyclone separator is connected to the outlet of the extraction module. The outlet of the cyclone separator is connected to the first inlet of the heat exchanger. The first outlet of the heat exchanger is connected to the inlet of the condensation separation device. The outlet of the condensation separation device is connected to the inlet of the gas separation device. The liquid outlet of the condensation separation device discharges condensed liquid products. The first outlet of the gas separation device is connected to the inlet of the CO2 capture device. The second outlet of the gas separation device is connected to the second inlet of the heat exchanger. The second outlet of the heat exchanger is connected to the first inlet of the heating furnace. The first outlet of the CO2 capture device is connected to the second inlet of the heating furnace. The second outlet of the CO2 capture device is connected to the inlet of the CO2 collection device. The outlet of the CO2 collection device is connected to the injection well. The outlet of the heating furnace is connected to two injection wells respectively.

[0010] A further improvement of the present invention is that: the liquid phase product separation module includes a centrifuge, the first liquid inlet of the centrifuge is connected to the outlet of the collection module, the second liquid inlet of the centrifuge is connected to the liquid outlet of the condensation separation device, and the centrifuge is used to separate water and tar.

[0011] A further improvement of the present invention is that a sampling module is provided between the extraction module and the liquid phase product separation module. The sampling module includes a collection and transportation pipeline, a sampling valve, a ball-feeding tube, and a blowout preventer. The outlet of the extraction module is connected to the inlet of the liquid phase product separation module through the collection and transportation pipeline. The collection and transportation pipeline is provided with a sampling valve and a ball-feeding tube, and the ball-feeding tube is connected to the blowout preventer.

[0012] A further improvement of the present invention is that: the lifting gas supply module includes a gas injection pipeline, the gas injection pipeline inlet is connected to a gas pump to supply gas for lifting liquid products, and a pneumatic diaphragm valve, a pressure gauge and a flow regulating valve are sequentially arranged in the gas injection pipeline along the gas movement direction, and the pneumatic diaphragm valve is electrically connected to a time controller.

[0013] A further improvement of the present invention is that: the inclined pipe forms a first angle with the axis of the production well, the first angle being [60°, 90°].

[0014] A further improvement of the present invention is that a three-phase thermal cable is provided inside the hollow sucker rod.

[0015] Secondly, the present invention provides a method for extracting oil and gas products from underground in-situ pyrolysis of coal, comprising the following steps:

[0016] A production well and several injection wells are constructed, with an inclined pipe installed between the bottom of each injection well and the bottom of the production well.

[0017] Fracturing the coal seam involves injecting hot carrier gas underground through several injection wells to heat the coal seam and cause pyrolysis.

[0018] The pyrolysis products are collected in the production well and extracted through the production module.

[0019] The gaseous products collected by the extraction module are sent to the gas phase product separation module to separate CO2, carrier gas and pyrolysis gas;

[0020] The gas phase product separation module obtains carrier gas, which is then used as purge gas and introduced into several injection wells. The purge gas collects the liquid products into the production wells and sends the liquid products through the production module into the liquid phase product separation module to obtain tar and water.

[0021] After pyrolysis, the CO2 obtained from the gaseous product separation module is introduced into several injection wells for CO2 sequestration.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] 1. In this invention, because the depth of the production well is greater than the depth of the injection well, and the injection well and production well are connected by an inclined pipe, the gravity effect caused by the height difference makes it easier for pyrolysis products to collect in the production well. Then, a production module set in the production well sends the gaseous and liquid products to a separation device for separation and purification. At the same time, the waste heat of the produced gas is fully utilized and the pyrolysis gas is burned for heating, thus improving energy utilization efficiency. Under the circumstances described in this invention, the difficulty of collecting liquid products is greatly reduced, and the recovery rate is significantly improved.

[0024] 2. This invention uses a heat exchanger to exchange heat between the gaseous products and the carrier gas, thereby reducing the temperature of the gaseous products to facilitate subsequent condensation and separation, and increasing the temperature of the carrier gas to facilitate subsequent heating in the furnace, thus making efficient use of thermal energy.

[0025] 3. This invention provides two methods for lifting liquid products, which are suitable for different working conditions and have a wide range of applications. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] In the attached diagram:

[0028] Figure 1 This is a schematic diagram of the structure of an oil and gas product extraction system for underground in-situ pyrolysis of coal according to the present invention.

[0029] Figure 2 This is a schematic diagram of the structure of the first extraction module in the oil and gas product extraction system of underground in-situ coal pyrolysis according to the present invention.

[0030] Figure 3 This is a schematic diagram of the structure of the second extraction module in the oil and gas product extraction system of underground in-situ coal pyrolysis according to the present invention.

[0031] Figure 4 This is a diagram showing the layout of injection wells and production wells in an oil and gas product extraction system for underground in-situ coal pyrolysis according to the present invention.

[0032] 1. Coal seam; 2. Interbedded gangue layer; 3. New energy power generation device; 4. Heater; 5. Cyclone separator; 6. Heating furnace; 7. Heat exchanger; 8. CO2 capture device; 9. CO2 collection device; 10. Gas separation device; 11. Condensation separation device; 12. Centrifuge; 13. First included angle; 14. One-way valve; 15. Tube shoe; 16. First casing; 17. Packer; 18. Spiral blade; 19. Oil drum; 20. Second casing; 21. First oil pipe; 22. Gas lift valve; 23. Cement ring; 24. Gas injection line; 25. Time controller; 26. Gas 27. Dynamic diaphragm valve; 28. Pressure gauge; 29. ​​Flow regulating valve; 30. Valve; 31. Blowout preventer; 32. Ball drop tube; 33. Sampling valve; 34. Gathering and transmission pipeline; 35. Plug; 36. Screen pipe; 37. Oil pump; 38. Third casing; 39. Fourth casing; 40. Fifth casing; 41. Cable; 42. Solid sucker rod; 43. Hollow joint; 44. Hollow sucker rod; 45. Second tubing; 46. Cable clamp; 47. Three-phase hot cable; 48. Hollow polished rod; 49. Cable outlet; 50. Injection well; 51. Production well; 52. Inclined pipe. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0034] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0035] Example 1

[0036] A coal underground in-situ pyrolysis oil and gas product extraction system, such as Figures 1-2As shown, the system includes several injection wells 49 vertically arranged within the coal seam 1, with production wells 50 located between the injection wells 49. The bottoms of the injection wells 49 and the bottoms of the production wells 50 are connected by inclined pipes 51. The first angle 13 between the inclined pipes 51 and the axis of the production wells 50 is [60°, 90°]. A second casing 20 is installed inside the production well 50. A first through hole is opened on the bottom side wall of the second casing 20, which communicates with the inclined pipes 51. A first casing 16 is installed inside the second casing 20. A packer 17 is installed on the side wall of the first casing 16. An oil cylinder 19 is installed inside the first casing 16. A first oil pipe 21 is installed inside the oil cylinder 19. An opening is opened at the bottom of the oil cylinder 19. There is a one-way valve 14. A first space is formed between the first sleeve 16 and the second sleeve 20. A second space is formed between the first sleeve 16 and the oil cylinder 19. A pipe shoe 15 is provided at the bottom of the second space. A spiral blade 18 is provided at the bottom of the first oil pipe 21. An air lift valve 22 is provided on the first oil pipe 21. The air outlet of the first space is connected to the air inlet of the gas phase product separation module. The second space is filled with a heat-insulating medium. The feed inlet of the second space is connected to the discharge outlet of the heater 4. The feed inlet of the heater 4 is connected to the discharge outlet of the second space. The heat-insulating medium is heated by the heater 4. The oil cylinder 19 is connected to the lifting gas supply module. The outlet of the first oil pipe 21 is connected to the liquid phase product separation module.

[0037] Specifically, the first extraction module includes a one-way valve 14, a tube shoe 15, a first casing 16, a packer 17, a spiral blade 18, an oil cylinder 19, a second casing 20, a first oil pipe 21, and an air lift valve 22.

[0038] Specifically, the gas phase product separation module includes a cyclone separator 5, a heat exchanger 7, a condensation separation device 11, a gas separation device 10, a CO2 capture device 8, a CO2 collection device 9, and a heating furnace 6. The inlet of the cyclone separator 5 is connected to the outlet of the first space, the outlet of the cyclone separator 5 is connected to the first inlet of the heat exchanger 7, the first outlet of the heat exchanger 7 is connected to the inlet of the condensation separation device 11, the outlet of the condensation separation device 11 is connected to the inlet of the gas separation device 10, and the outlet of the condensation separation device 11 discharges condensed liquid. The product, the first outlet of the gas separation device 10 is connected to the inlet of the CO2 capture device 8, the second outlet of the gas separation device 10 is connected to the second inlet of the heat exchanger 7, the second outlet of the heat exchanger 7 is connected to the first inlet of the heating furnace 6, the first outlet of the CO2 capture device 8 is connected to the second inlet of the heating furnace 6, the second outlet of the CO2 capture device 8 is connected to the inlet of the CO2 collection device 9, the outlet of the CO2 collection device 9 is connected to the injection well 49, and the outlet of the heating furnace 6 is connected to each injection well 49 respectively.

[0039] Volatile products in the first space enter the cyclone separator 5 to separate solid particles and pure volatile products. The pure volatile products pass through the heat exchanger 7 and enter the condensation separation device 11. The condensation separation device 11 separates mixed gas and condensed liquid products from the pure volatile products. The mixed gas enters the gas separation device 10 to separate carrier gas and crude pyrolysis gas. The carrier gas exchanges heat with the pure volatile products through the heat exchanger 7. After the heat exchange is completed, the carrier gas enters the heating furnace 6 for heating. The heated carrier gas is then introduced into the injection well 49. The crude pyrolysis gas enters the CO2 capture device 8 to capture carbon dioxide and pyrolysis gas. The captured carbon dioxide enters the CO2 collection device 9. The collected carbon dioxide can be sent to the injection well 49 for storage. The pyrolysis gas enters the heating furnace 6 as fuel for combustion. The heating furnace 6 is also equipped with an external fuel inlet, which is used to provide the fuel and combustion aid required for combustion in the heating furnace 6. The pyrolysis gas can serve as part of the fuel, and the combustion aid can be air or oxygen-enriched gas.

[0040] Specifically, the liquid phase product separation module includes a centrifuge 12. The first liquid inlet of the centrifuge 12 is connected to the liquid outlet of the first oil pipe 21, and the second liquid inlet of the centrifuge 12 is connected to the liquid outlet of the condensation separation device 11. The centrifuge 12 obtains the condensed liquid product and the liquid product in the oil cylinder 19, and separates tar and pyrolysis water.

[0041] Specifically, a sampling module is provided between the liquid product separation module and the first oil pipe 21. The sampling module includes a gathering and transportation pipeline 33, a sampling valve 32, a ball-feeding tube 31, and a blowout preventer 30. The outlet of the first oil pipe 21 is connected to the inlet of the centrifuge 12 through the gathering and transportation pipeline 33. The gathering and transportation pipeline 33 is equipped with a sampling valve 32 and a ball-feeding tube 31. The ball-feeding tube 31 and the sampling valve 32 together form a sampling device, which can flexibly sample the produced oil. The ball-feeding tube 31 is connected to the blowout preventer 30 to prevent oil from overflowing during the subsequent gas lift process and contaminating the produced pipe fittings.

[0042] Specifically, the lifting gas supply module includes an injection line 24, a time controller 25, a pneumatic diaphragm valve 26, a pressure gauge 27, and a flow regulating valve 28. The air inlet of the oil cylinder 19 is connected to the air outlet of the injection line 24. The air inlet of the injection line 24 is connected to an air pump to supply gas for lifting the liquid product. The injection line 24 is equipped with a pneumatic diaphragm valve 26, a pressure gauge 27, and a flow regulating valve 28 in sequence along the gas movement direction. The pneumatic diaphragm valve 26 is electrically connected to the time controller 25. The intermittent injection switch formed by the time controller 25 and the pneumatic diaphragm valve 26 injects gas into the oil cylinder 19 at regular intervals.

[0043] Specifically, heater 4 is electrically connected to new energy power generation device 3.

[0044] Specifically, the one-way valve 14 is used to control the flow of pyrolysis oil into the oil drum 19 in one direction, and to prevent the oil from flowing out of the oil drum 19 during lifting; the tubing shoe 15 is used to prevent solid matter in the well from entering the first tubing 21, and at the same time guides the oil to more easily enter the bottom of the well and flow into the first tubing 21; the packer 17 is used to separate the liquid phase products at the bottom of the first tubing 21 from the insulation medium between the second space.

[0045] The oil drum 19 is used to hold the liquid products generated by pyrolysis; the first oil pipe 21 is the channel for the liquid products to be lifted out; the spiral blade 18 is used to generate spiral rotation when the oil is lifted out through the first oil pipe 21, thereby improving the fluidity of the oil.

[0046] Specifically, the gas lift valve 22 is the switch for the gas injection port on the lifting tubing, which can flexibly change the gas injection depth to adapt to changes in the fluid supply capacity of the production well.

[0047] A cement ring 23 is provided around the wellhead of the production well 50 to fix the production well 50.

[0048] The gas injection line 24 is the injection channel for the lifting gas. The lifting gas can be an inert gas such as N2 or CO2, or a reducing gas. The time controller 25 is used to control the opening and closing of the pneumatic diaphragm valve 26. It has a time setting button on its panel, which can set the control time according to the intermittent gas injection cycle to achieve the purpose of intermittent gas injection. The pneumatic diaphragm valve 26 is used in conjunction with the time controller 25 and is the switch for controlling the injected gas in intermittent gas lift.

[0049] Pressure gauge 27 is used to monitor the pressure of the oil and gas transmission pipeline so that flow regulating valve 28 can adjust the opening and closing degree in a timely manner; flow regulating valve 28 is used to adjust the flow rate of the injection and production pipelines in a timely manner according to the reading of pressure gauge 27 and the requirements of the extraction process.

[0050] Cyclone separator 5 is used to separate the volatile products obtained from pyrolysis by cyclone separation, and to separate the solid impurities mixed in the volatile products; heating furnace 6 is used to heat the carrier gas, which is mainly high-temperature steam, CO2 and N2, etc. The fuel used in heating furnace 6 is mainly pyrolysis gas and external fuel.

[0051] The pyrolysis gas mainly consists of small molecule alkanes, H2, and CO; the external fuels are mainly gaseous and liquid fuels, including natural gas and methane, and liquid fuels including coal-water slurry or oil; the combustion aid is oxygen or air.

[0052] Heat exchanger 7 is used to exchange heat between the gaseous products obtained from pyrolysis and the low-temperature carrier gas. On the one hand, it lowers the temperature of the volatile products, making it easier for subsequent condensation and separation. On the other hand, it can further improve energy utilization by initially heating the low-temperature carrier gas.

[0053] CO2 capture device 8 is used to capture CO2 gas in crude pyrolysis gas, and CO2 collection device 9 is used to collect CO2 gas separated from crude pyrolysis gas. After the coal seam 1 is fully pyrolyzed, the CO2 gas is transported to the underground coke layer for CO2 sequestration.

[0054] The CO2 capture device 8 is mainly filled with solid adsorbent materials such as CaO, MgO, Li2ZrO3, Li4SiO4, and activated carbon, which are used to efficiently adsorb and separate CO2.

[0055] The condensation separation device 11 has a temperature below 30°C and uses water cooling, air cooling, or a combination of water cooling and air cooling to achieve the condensation of the liquid phase products obtained from pyrolysis.

[0056] The new energy power generation device 3 is used to provide energy to the heater 4; the heater 4 is used to heat the insulation medium in the second space. After the insulation medium is heated, it enters the second space to maintain the temperature of the production well 50 at no less than 360°C. The ratio of gaseous products to liquid products in the produced products can be indirectly controlled by controlling the heating temperature of the insulation medium.

[0057] The new energy power generation device 3 can use new energy sources such as solar energy and wind energy to generate electricity and supply energy; the heat preservation medium is high-temperature superheated steam or high-temperature molten salt, among which potassium-based binary molten salt and sodium-based binary molten salt with good heat storage and thermal conductivity can be selected.

[0058] Specifically, underground coal seam 1 and interbedded gangue layer 2 coexist.

[0059] Example 2

[0060] A method for extracting oil and gas products from underground in-situ coal pyrolysis, based on an oil and gas product extraction system from underground in-situ coal pyrolysis in Example 1, such as... Figures 1-2 As shown, it includes the following steps:

[0061] According to requirements, injection well 49 and production well 50 are drilled. An inclined pipe 51 is installed between injection well 49 and production well 50. The angle between the inclined pipe 51 and the axis of production well 50 is [60°, 90°]. Cement is injected to form a cement ring 23 for well cementing, and the coal seam is fracturing to form fractures. First, superheated carrier gas, generally superheated N2, superheated CO2, or superheated steam, is injected into the coal seam from the injection well. The temperature is generally above 600°C. The coal seam is heated to pyrolyze and produce oil and gas products. The new energy power generation device 3 and heater 4 are turned on to heat the circulating medium in the insulation casing. The circulating medium is generally superheated steam or high-temperature molten salt. The temperature inside the insulation casing is generally not lower than 360°C. The heating temperature of the circulating medium is controlled according to the ratio of gaseous products to liquid products in the produced products required for actual production. The volatile products obtained from pyrolysis are extracted from the first space between the first casing 16 and the second casing 20. The gas then passes through a cyclone separator 5 for gas-solid separation, a heat exchanger 7 for heat exchange and cooling, and a condensation separation device 11 for gas-liquid separation. The temperature is generally below 50°C and water cooling, air cooling, or a combination of water and air cooling are used. The gas then passes through a gas separation device 10 and a CO2 capture device 8. The CO2 capture device 8 mainly contains solid adsorbent materials such as CaO, MgO, Li2ZrO3, Li4SiO4, and activated carbon for pyrolysis gas purification and carrier gas separation. Finally, the obtained pyrolysis gas is burned in a heating furnace 6 to heat the carrier gas, and the small amount of liquid product obtained is separated into oil and water by a centrifuge 12. The large amount of liquid products obtained from pyrolysis are purged by carrier gas and flow into the production well through an inclined pipe. In the production well, they can enter the oil tank 19 through the first production module, i.e., through the one-way valve 14 at the bottom of the oil tank 19. The intermittent gas injection switch composed of time controller 25 and pneumatic diaphragm valve 26 injects gas into the oil tank 19 at regular intervals, lifting the liquid products in the oil tank 19 to the ground. After the liquid products are lifted out, a demulsifier is first added, and then they are sent to centrifuge 12 for oil-water separation to obtain tar.

[0062] Example 3

[0063] A coal underground in-situ pyrolysis oil and gas product extraction system, compared with Example 1, replaces the first extraction module with a second extraction module, such as... Figure 3 As shown, it includes:

[0064] The production well 50 is equipped with a third casing 37. The bottom side wall of the third casing 37 has a second through hole, which is connected to the inclined pipe 51. The first included angle 13 between the inclined pipe 51 and the axis of the production well 50 is [60°, 90°]. The third casing 37 is equipped with a fourth casing 38. The fourth casing 38 is equipped with a fifth casing 39. The fifth casing 39 is equipped with a second oil pipe 44. The third space is between the third casing 37 and the fourth casing 38. The bottom of the third space is equipped with a pipe shoe 15. The air outlet of the third space is connected to the air inlet of the gas phase product separation module. The fourth space is between the fourth casing 38 and the fifth casing 39. The fourth space is filled with a heat-insulating medium. The outlet of the fourth space is connected to the inlet of the heater 4. The outlet of the heater is connected to the inlet of the fourth space. The heat-insulating medium in the fourth space is heated by the heater 4. The fifth space is between the fifth casing 39 and the second oil pipe 44. The fifth space is used to temporarily store liquid phase products.

[0065] The second oil pipe 44 is provided with, from bottom to top, a plug 34, a screen pipe 35, an oil pump 36, a solid sucker rod 41, a hollow joint 42, and a hollow sucker rod 43.

[0066] Plug 34 is used to seal the second oil pipe 44;

[0067] Screen tube 35 is used to filter oil and prevent solid impurities from entering the second oil pipe 44.

[0068] The oil pump 36 provides power to extract oil from the lower part of the production well 50 to the surface; the solid sucker rod 41 connects the oil pump 36 and the hollow sucker rod 43 to transmit power; the oil pump 36 obtains power through the cable 40, and the cable 40 and the second tubing 44 are fixed together by the cable clamp 45; the hollow sucker rod 43 is a hollow circular channel, which facilitates the injection of heat carrier or the insertion of three-phase heat cable 46 into the well for viscosity reduction and wax melting, thereby improving the fluidity of the oil; the hollow connector 42 connects the hollow sucker rod 43 and the solid sucker rod 41; a hollow polished rod 47 and a cable outlet 48 are provided above the production well 50, and the hollow polished rod 47 is connected to the hollow sucker rod 43 for inserting the cable 40 and the three-phase heat cable 46.

[0069] The three-phase heat cable 46 is placed inside the hollow sucker rod 43, which is filled with transformer oil and heat dissipation fluid, to heat the oil during the lifting process, reduce its viscosity, and improve its fluidity.

[0070] Liquid products can also be extracted through the second production module. A large quantity of liquid products is flushed out by carrier gas and flows into the production well via an inclined pipe. The oil pump 36 and three-phase heating cable 46 are then activated to lift the pyrolysis-derived liquid products to the surface. After adding a demulsifier, the products are sent to a centrifuge 12 for oil-water separation, thereby obtaining pyrolytic tar. The demulsifier is mainly a cationic or anionic demulsifier, such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfates, or quaternary ammonium salts.

[0071] Example 4

[0072] A method for extracting oil and gas products from underground in-situ pyrolysis of coal mainly includes the following steps:

[0073] Injection and production wells are drilled as required. The injection well section includes a vertical well and an inclined pipe with an inclination angle of 60°. An oil and gas production device is installed in the production well, cement is injected to solidify the well, and the coal seam is fractured to create fissures. First, superheated N2 carrier gas at 600°C is injected into the coal seam from the injection well to heat the coal seam and produce oil and gas products through pyrolysis. The new energy power generation device 3 and heater 4 are activated to heat the superheated steam in the insulation casing. The heating temperature of the superheated steam is controlled according to the ratio of gaseous to liquid products in the produced products, as required by actual production needs. The temperature inside the insulation casing is generally not lower than 360°C. The volatile products obtained from pyrolysis are extracted from the annular space between the first casing 16 and the second casing 20, and then sequentially pass through a cyclone separator 5 for gas-solid separation. Heat exchanger 7 performs heat exchange and cooling. The gas-liquid separation is carried out by condensation separation device 11. The condensation separation device 11 uses air cooling to keep the temperature inside the device below 30°C. The gas then passes through gas separation device 10 and CO2 capture device 8. The CO2 capture device 8 is mainly filled with solid adsorbent materials such as CaO, MgO, Li2ZrO3, Li4SiO4, and activated carbon to purify the pyrolysis gas and separate the carrier gas. Finally, the obtained pyrolysis gas is burned in heating furnace 6 to heat the carrier gas. The small amount of liquid product obtained is separated into oil and water by centrifuge 12. A large amount of liquid phase product can be produced through the first production module. The liquid phase product obtained from pyrolysis is purged with carrier gas and flows into the production well via an inclined pipe. It then enters the oil tank 19 through a one-way valve 14 at the bottom of the tank. An intermittent gas injection switch, consisting of a time controller 25 and a pneumatic diaphragm valve 26, periodically injects gas into the oil tank 19, lifting the liquid phase product to the surface. After lifting, a demulsifier is added, primarily cationic or anionic demulsifiers such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfates, and quaternary ammonium salts. The product is then sent to a centrifuge 12 for oil-water separation to obtain tar. A large amount of liquid phase product can also be produced through the second production module. The liquid product is purged with carrier gas and flows into the production well via an inclined pipe. The oil pump 36 and three-phase heating cable 46 are activated to lift the pyrolysis liquid product to the surface. After adding a demulsifier, the product is sent to a centrifuge 12 for oil-water separation to obtain pyrolytic tar.

[0074] Example 5

[0075] A method for extracting oil and gas products from underground in-situ pyrolysis of coal mainly includes the following steps:

[0076] Injection and production wells are drilled as required. The injection well section includes a vertical well and an inclined pipe with an inclination angle of 70°. An oil and gas production device is installed in the production well, cement is injected to cement the well, and the coal seam is fractured to create fissures. First, superheated CO2 carrier gas is injected into the coal seam at 700°C from the injection well to heat the coal seam and produce oil and gas products through pyrolysis. The new energy power generation device 3 and heater 4 are then activated to heat the high-temperature molten salt in the insulation casing. The heating temperature of the high-temperature molten salt is controlled according to the ratio of gaseous to liquid phase products required for actual production. The temperature inside the insulation casing is generally not lower than 360°C. The volatile products obtained from pyrolysis are extracted from the annular space between the first casing 16 and the second casing 20, and then sequentially pass through a cyclone separator 5 for gas-solid separation. Heat exchanger 7 is used for heat exchange and cooling. The gas-liquid separation is carried out by condensation separation device 11. The condensation separation device 11 uses water cooling to keep the temperature inside the device below 30°C. The gas then passes through gas separation device 10 and CO2 capture device 8. The CO2 capture device 8 is mainly filled with solid adsorbent materials such as CaO, MgO, Li2ZrO3, Li4SiO4, and activated carbon to purify the pyrolysis gas and separate the carrier gas. Finally, the obtained pyrolysis gas is burned in heating furnace 6 to heat the carrier gas. The small amount of liquid product obtained is separated into oil and water by centrifuge 12. A large amount of liquid phase product can be produced through the first production module, i.e., the large amount of liquid phase product obtained by pyrolysis is purged by carrier gas and flows into the production well from the inclined horizontal well. It then enters the oil cylinder 1919 through the one-way valve 14 at the bottom of the oil cylinder 19. The intermittent gas injection switch composed of the time controller 25 and the pneumatic diaphragm valve 26 injects gas into the oil cylinder 19 at regular intervals, lifting the liquid phase product in the oil cylinder 19 to the surface. After the liquid phase product is lifted out, a demulsifier is first added, mainly cationic or anionic demulsifiers such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfate salts, and quaternary ammonium salts. Then it is sent to the centrifuge 12 for oil-water separation to obtain tar. A large amount of liquid products can also be produced through the second production module. The large amount of liquid products are purged by carrier gas and flow into the production well from the inclined horizontal well. The oil pump 36 and the three-phase heat cable 46 are turned on to lift the liquid products obtained by pyrolysis to the surface. After adding demulsifiers, mainly cationic or anionic demulsifiers such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfate salts, and quaternary ammonium salts, the products are sent to the centrifuge 12 for oil-water separation to obtain pyrolytic tar.

[0077] Example 6

[0078] A method for extracting oil and gas products from underground in-situ pyrolysis of coal mainly includes the following steps:

[0079] Injection and production wells are drilled as required. The injection well section includes a vertical well and an inclined pipe with an inclination angle of 80°. An oil and gas production device is installed in the production well, cement is injected to cement the well, and the coal seam is fractured to create fissures. First, superheated steam is injected into the coal seam from the injection well at a temperature of 800°C to heat the coal seam and produce oil and gas products through pyrolysis. The new energy power generation device 3 and heater 4 are then activated to heat the high-temperature molten salt in the insulation casing. The heating temperature of the high-temperature molten salt is controlled according to the ratio of gaseous to liquid products required for actual production. The temperature inside the insulation casing is generally not lower than 360°C. The volatile products obtained from pyrolysis are extracted from the annular space between the first casing 16 and the second casing 20, and then sequentially pass through a cyclone separator 5 for gas-solid separation. Through heat exchange... Heat exchange and cooling are performed in device 7. Gas-liquid separation is performed in condensation separation device 11. Condensation separation device 11 uses a combination of water cooling and air cooling to keep the temperature inside the device below 30°C. Gas separation device 10 and CO2 capture device 8 are used to purify pyrolysis gas and separate carrier gas. The pyrolysis gas is then burned in heating furnace 6 to heat the carrier gas. The small amount of liquid product is separated into oil and water by centrifuge 12. A large amount of liquid phase product can be produced through the first production module, i.e., the large amount of liquid phase product obtained by pyrolysis is purged by carrier gas and flows into the production well from the inclined horizontal well. It then enters the oil cylinder 19 through the one-way valve 14 at the bottom of the oil cylinder 19. The intermittent gas injection switch, which is composed of time controller 25 and pneumatic diaphragm valve 26, injects gas into the oil cylinder 19 at regular intervals, lifting the liquid phase product in the oil cylinder 19 to the surface. After the liquid phase product is lifted out, a demulsifier is first added, mainly cationic or anionic demulsifiers such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfate salts, and quaternary ammonium salts. Then it is sent to centrifuge 12 for oil-water separation to obtain tar. A large amount of liquid products can also be produced through the second production module. The large amount of liquid products are purged by carrier gas and flow into the production well from the inclined horizontal well. The oil pump 36 and the three-phase heat cable 46 are turned on to lift the liquid products obtained by pyrolysis to the surface. After adding demulsifiers, mainly cationic or anionic demulsifiers such as carboxylates, sulfonates, polyoxyethylene fatty acid sulfate salts, and quaternary ammonium salts, the products are sent to the centrifuge 12 for oil-water separation to obtain pyrolytic tar.

[0080] Example 7

[0081] A coal underground in-situ pyrolysis oil and gas product extraction system, such as Figure 4 As shown, there can be several injection wells 49, which are evenly arranged around the production well 50.

[0082] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A coal underground in-situ pyrolysis oil and gas product extraction system, characterized in that, The system includes a production well (50), and several injection wells (49) are evenly arranged around the production well (50). The bottom of each injection well (49) is connected to the bottom of the production well (50) through an inclined pipe (51). The depth of the production well (50) is greater than the depth of the injection well (49). The production well (50) is equipped with a production module. The production module is used to extract gaseous and liquid products in the production well (50). The outlet of the production module is connected to the inlet of the gaseous product separation module. The outlet of the gaseous product separation module is connected to several injection wells (49). The outlet of the production module is connected to the inlet of the liquid product separation module. The production module includes a second casing (20), which is installed inside the production well (50). The bottom sidewall of the second casing (20) has several first through holes, each of which is connected to an inclined pipe (51). The second casing (20) contains a first casing (16), which contains an oil cylinder (19). The oil cylinder (19) contains a first oil pipe (21). The bottom of the oil cylinder (19) has a one-way valve (14). A first space is formed between the first casing (16) and the second casing (20), and a second space is formed between the first casing (16) and the oil cylinder (19). The first oil pipe (21) is equipped with a gas lift valve (22). The outlet of the first space is connected to the inlet of the gas phase product separation module. The second space is filled with a heat-insulating medium. The inlet of the oil cylinder (19) is connected to the outlet of the lifting gas supply module. The outlet of the first oil pipe (21) is... The production module is connected to the inlet of the liquid phase product separation module; the production module includes a third casing (37), which is installed inside the production well (50). A second through hole is opened on the bottom side wall of the third casing (37), which is connected to the inclined pipe (51). A fourth casing (38) is installed inside the third casing (37), and a fifth casing (39) is installed inside the fourth casing (38). A second oil pipe (44) is installed inside the fifth casing (39). The third space is between the third sleeve (37) and the fourth sleeve (38). The outlet of the third space is connected to the inlet of the gas phase product separation module. The fourth space is between the fourth sleeve (38) and the fifth sleeve (39). The fourth space is filled with heat-insulating medium. The second oil pipe (44) is provided with a plug (34), a screen pipe (35), an oil pump (36), a solid sucker rod (41), a hollow joint (42), and a hollow sucker rod (43) from bottom to top.

2. The oil and gas product extraction system for underground in-situ coal pyrolysis according to claim 1, characterized in that, The gas phase product separation module includes a cyclone separator (5), a heat exchanger (7), a condensation separation device (11), a gas separation device (10), a CO2 capture device (8), a CO2 collection device (9), and a heating furnace (6). The inlet of the cyclone separator (5) is connected to the outlet of the extraction module. The outlet of the cyclone separator (5) is connected to the first inlet of the heat exchanger (7). The first outlet of the heat exchanger (7) is connected to the inlet of the condensation separation device (11). The outlet of the condensation separation device (11) is connected to the inlet of the gas separation device (10). The liquid outlet of the condensation separation device (11) discharges condensed liquid products. The first outlet of the gas separation device (10) is connected to the inlet of the CO2 capture device (8), the second outlet of the gas separation device (10) is connected to the second inlet of the heat exchanger (7), the second outlet of the heat exchanger (7) is connected to the first inlet of the heating furnace (6), the first outlet of the CO2 capture device (8) is connected to the second inlet of the heating furnace (6), the second outlet of the CO2 capture device (8) is connected to the inlet of the CO2 collection device (9), the outlet of the CO2 collection device (9) is connected to the injection well (49), and the outlet of the heating furnace (6) is connected to the two injection wells (49) respectively.

3. The oil and gas product extraction system for underground in-situ coal pyrolysis according to claim 2, characterized in that, The liquid phase product separation module includes a centrifuge (12), the first inlet of the centrifuge (12) is connected to the outlet of the extraction module, the second inlet of the centrifuge (12) is connected to the outlet of the condensation separation device (11), and the centrifuge (12) is used to separate water and tar.

4. The oil and gas product extraction system for underground in-situ coal pyrolysis according to claim 1, characterized in that, A sampling module is provided between the extraction module and the liquid product separation module. The sampling module includes a collection and transportation pipeline (33), a sampling valve (32), a ball-feeding tube (31), and a blowout preventer (30). The outlet of the extraction module is connected to the inlet of the liquid product separation module through the collection and transportation pipeline (33). The collection and transportation pipeline (33) is equipped with a sampling valve (32) and a ball-feeding tube (31). The ball-feeding tube (31) is connected to the blowout preventer (30).

5. The oil and gas product extraction system for underground in-situ coal pyrolysis according to claim 1, characterized in that, The lifting gas supply module includes a gas injection line (24). The gas injection line (24) has an inlet connected to a gas pump to supply gas for lifting the liquid phase product. The gas injection line (24) is provided with a pneumatic diaphragm valve (26), a pressure gauge (27), and a flow regulating valve (28) in sequence along the gas movement direction. The pneumatic diaphragm valve (26) is electrically connected to a time controller (25).

6. The oil and gas product extraction system for underground in-situ coal pyrolysis according to claim 1, characterized in that, The inclined pipe (51) forms a first angle (13) with the axis of the production well (50), and the first angle (13) belongs to [60°, 90°].

7. A coal underground in-situ pyrolysis oil and gas product extraction system according to claim 1, characterized in that, The hollow sucker rod (43) is equipped with a three-phase heat cable (46).

8. A method for extracting oil and gas products from underground in-situ pyrolysis of coal, characterized in that, The oil and gas product extraction system based on any one of claims 1 to 7 includes the following steps: A production well (50) and several injection wells (49) are constructed, and an inclined pipe (51) is provided between the bottom of each injection well (49) and the bottom of the production well (50). The coal seam (1) is fractured, and hot carrier gas is injected underground through several injection wells (49) to heat the coal seam and cause pyrolysis; The pyrolysis products are collected in the production well and extracted through the production module. The gaseous products collected by the extraction module are sent to the gas phase product separation module to separate CO2, carrier gas and pyrolysis gas; The gas phase product separation module obtains carrier gas as purging gas and introduces it into several injection wells (49). The purging gas collects the liquid products into the production wells (50) and sends the liquid products into the liquid phase product separation module through the production module to obtain tar and water. After pyrolysis, CO2 obtained from the gas phase product separation module is introduced into several injection wells (50) for CO2 storage.

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