CN-121975538-A - Multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system and method

CN121975538ACN 121975538 ACN121975538 ACN 121975538ACN-121975538-A

Abstract

The invention discloses a multifluid synergistic heating and coke-inhibiting and oil-increasing oil-rich coal in-situ pyrolysis system and method. The system adopts a regular hexagon underground pyrolysis network comprising a combustion input/output well, a heat injection well and a production well, utilizes in-situ controllable combustion to release heat and is coupled with high-temperature supercritical CO 2 to heat a coal bed in a convection manner, sprays low-temperature supercritical CO 2 into an independent fluid channel of the production well to enable the low-temperature supercritical CO 2 to be in direct contact with pyrolysis products for heat exchange, and is matched with a bottom hole liquid collecting, heating and pumping device to effectively inhibit secondary reactions of tar and improve fluidity, adopts superheated steam pulse injection, eliminates carbon deposition, blocks coking and dredges pores through the action of a catalyst bed layer, and continuously injects steam after pyrolysis is finished to realize gasification exploitation of residual semicoke. The invention integrates the functions of combustion heat supply, supercritical CO 2 heat carrying/quenching, steam gasification coke inhibition, multistage waste heat recovery and the like, and remarkably improves the tar yield, quality and energy utilization efficiency of in-situ exploitation of the oil-rich coal.

Inventors

WANG CHANGAN
CHEN MEIJING
LIU KE
ZHANG YIXIANG
WANG QINGWEI
CHANG LIUJUN
CHE DEFU

Assignees

西安交通大学

Dates

Publication Date: 20260505
Application Date: 20251230

Claims (10)

1. A multi-fluid collaborative heat supply and tar inhibition oil increase rich coal in-situ pyrolysis system is characterized by comprising a combustion input well (3), a combustion output well (6), a first heat injection well (4), a first production well (7), a second heat injection well (5) and a second production well (8) which are excavated from the ground vertically downwards at a rich coal seam (2), wherein a middle horizontal well (9) which is used for communicating the combustion input well (3) and the combustion output well (6), a lower end horizontal well (11) which is used for communicating the first heat injection well (4) and the first production well (7), an upper end horizontal well (10) which is used for communicating the second heat injection well (5) and the second production well (8), a catalyst bed (39) is paved at the position, close to the lower end horizontal well (11), of the combustion input well (3) is provided with an ignition device (12), the outsides of the first production well (7) and the second production well (8) are both excavated, a heat preservation interlayer (36) is arranged, a first heat preservation interlayer (37) is arranged between the first production well (7) and the second production well (8) and a fluid channel (37) is formed by a fluid channel (37), a liquid collecting pit (40) is dug at the bottom ends of the first production well (7) and the second production well (8), and a heating element (41) and a micropump (42) are arranged in the liquid collecting pit (40); Starting a controllable combustion reaction under an ignition heating path, wherein heat released by combustion is used for heating coal beds at the upper and lower end areas, high-temperature supercritical CO 2 (27) enters a first heat injection well (4) and a second heat injection well (5), the coal beds (2) are heated along a lower horizontal well (11) and an upper horizontal well (10), the other part of supercritical CO 2 (26) enters an independent fluid channel (37) and is intermittently sprayed along an annular nozzle (38) arranged at the lower end to be discharged, the high-temperature supercritical CO 2 (27) and the sprayed low-temperature supercritical CO 2 (26) are in direct contact with each other to mix pyrolysis products, the mixed high-temperature supercritical CO 2 (43) flows out from bottom to top along a first production well (7) and a second production well (8), so that the pyrolysis products are rapidly cooled, part of tar after being rapidly cooled is condensed and is in a liquid collecting pit (40), the heated tar is collected together with a gaseous mixture under the pushing action of a micro pump (42), high-pressure low-oxygen concentration mixed gas (25) flows out, and then enters a combustion reaction gas under the high-temperature mixed gas (35) to be mixed combustion gas under the condition, and the high-oxygen concentration mixed gas can be oxidized under the control, and the combustion reaction gas can flow under the condition (3) and the combustion reaction path is controlled in situ, and the mixed combustion gas can be oxidized under the condition; The superheated steam (33) is injected into the coal bed (2) along the first heat injection well (4) and the second heat injection well (5) in a pulse mode, and is subjected to gasification reaction with carbon deposition of pyrolysis products under the action of the catalyst bed (39), active hydrogen in the superheated steam (33) environment is filled to react with carbon deposition precursors, the generated carbon deposition can be removed while a coking path is blocked, a large amount of semicoke products remain underground after the in-situ pyrolysis reaction of the rich coal is finished, and the semicoke products are continuously injected into the stratum along the first heat injection well (4) and the second heat injection well (5) to perform gasification reaction.
2. The multi-fluid synergistic heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 1, wherein the high-pressure low-oxygen concentration mixed gas (25) is mixed by air (13) and boiler vexation gas (14) through a mixing unit (15), then is pressurized through a first compressor (16) and is fed into a combustion input well (3), the coal bed (2) is ignited through an ignition device (12), in-situ controllable combustion occurs, the combustion reaction advances along a middle horizontal well (9), a gas product (28) enters a first heat exchanger (17) after being lifted to the ground, and enters the mixing unit (15) after being cooled.
3. The multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 1, wherein the first production well (7) and the second production well (8) flow out of the mixed high temperature supercritical CO 2 (43) from bottom to top to enter the second heat exchanger (18), enter the first gas-liquid separation device (19) after heat exchange, the separated tar is collected into the oil storage device (23), the gas mixture enters the CO 2 separation device (20), the separated CO 2 is collected into the CO 2 gas storage device (21), and the residual pyrolysis gas is collected into the first gas storage device (24).
4. The multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 3, wherein a part of supercritical CO 2 formed by the CO 2 gas storage device (21) under the pressurizing action of the second compressor (22) enters the first heat exchanger (17), exchanges heat with the high-temperature controllable combustion gas product (28) to obtain high-temperature supercritical CO 2 (27), enters the first heat injection well (4) and the second heat injection well (5), and the other part of supercritical CO 2 enters independent fluid channels (37) inside the first production well (7) and the second production well (8).
5. The multi-fluid synergistic heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 2 or 3, wherein a part of the high-pressure low-oxygen concentration mixed gas (25) enters a second heat exchanger (18), exchanges heat with a first production well (7), a second production well (8) outflow pyrolysis product and supercritical CO 2 mixture (43), and enters a combustion input well (3) after heating.
6. The multi-fluid collaborative heat supply and coking and oil increase rich coal in-situ pyrolysis system according to claim 1, wherein the superheated steam (33) is formed by a water supply pump (29) and a boiler (30) and is injected into the coal bed (2) along a first heat injection well (4) and a second heat injection well (5) in a pulse mode, gasification reaction is carried out on the superheated steam and carbon deposit products under the action of a catalyst bed layer (39), active hydrogen in the environment of the superheated steam (33) is filled to react with carbon deposit precursors, the superheated steam mixed reaction product (44) flows out along the first production well (7) and the second production well (8) and then enters a third heat exchanger (31), water (35) subjected to heat exchange and cooling enters the water supply pump (29), the above processes are circulated, residual gas is collected into a second gas storage device (32), high-pressure water prepared by the water supply pump enters the boiler (30) through the third heat exchanger (31) and preheated water (34) generated by heat exchange of a high-pressure gas mixture (44).
7. The multi-fluid collaborative heat supply and tar-inhibiting and oil-increasing rich coal in-situ pyrolysis system according to claim 1, wherein the heating element (41) is set at a temperature greater than the tar pour point, i.e., greater than 50 ℃, and lower than the secondary reaction temperature of the tar, i.e., less than 350 ℃.
8. The multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 1, wherein the catalyst bed (39) adopts an alkali metal catalyst which accelerates the removal of carbon deposition gasification and simultaneously promotes the formation of hydrogenation environment.
9. The multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system according to claim 1, wherein the combustion input well (3), the combustion output well (6), the first heat injection well (4), the first production well (7), the second heat injection well (5) and the second production well (8) are arranged in a regular hexagon in the overlooking direction, and the vertical wells which are communicated with each other are positioned at two opposite vertex positions.
10. A multi-fluid synergic heat supply and coke inhibition oil enrichment coal in-situ pyrolysis method of a pyrolysis system according to claim 1, characterized by comprising the following steps: 1) mixed gas with required oxygen concentration is configured by air (13) and boiler flue gas (14) to enter a mixing unit (15), enters a combustion input well (3) under the pressurization of a first compressor (16), is ignited by a well bottom ignition device (12) after a controllable combustion reaction under an ignition heating path is started, a coal bed (2) is subjected to in-situ controllable combustion, the combustion reaction is continuously propelled forwards along a middle horizontal well (9), a controllable combustion area is gradually diffused around, heat released by the combustion is used for heating the coal bed in the upper and lower end areas, a gas product (28) enters a first heat exchanger (17) after being lifted to the ground from a combustion outflow well (6), enters the mixing unit (15) after being cooled, and replaces part of the mixed air (13) of the boiler flue gas (14) to obtain the mixed gas with low oxygen concentration to circulate above; 2) Part of supercritical CO 2 enters a first heat exchanger (17) under the pressurization of a second compressor (22), heat is exchanged with a high-temperature controllable combustion gas product (28) to obtain high-temperature supercritical CO 2 (27), the high-temperature supercritical CO 2 enters a first heat injection well (4) and a second heat injection well (5), the coal seam (2) is continuously heated along a fluid channel, the other part of supercritical CO 2 enters an independent fluid channel (37) at the inner sides of the first production well (7) and the second production well (8) under the pressurization of the second compressor (22), the high-temperature supercritical CO 2 (43) is intermittently sprayed along an annular nozzle (38) arranged at the lower end of the well, the pyrolysis product is directly contacted and mixed with the sprayed low-temperature supercritical CO 2 (26) in the process of flowing out from bottom to top along the first production well (7) and the second production well (8), the rapid cooling of the pyrolysis product is realized, the secondary reaction of tar caused by long-time retention is avoided, the rapid cooling part of the tar is condensed and collected in a liquid collecting tank (40), the liquid is heated, and the liquid is heated in a micro-pump (42) to reduce the viscosity, and the fluidity of the mixture is increased; 3) The pyrolysis product and supercritical CO 2 (43) flow out along a first production well (7) and a second production well (8) and then enter a second heat exchanger (18), after heat exchange, enter a first gas-liquid separation device (19), tar obtained by separation is collected into an oil storage device (23), a gas mixture enters a CO 2 separation device (20), CO 2 obtained by separation is collected into a CO 2 gas storage device (21), and residual pyrolysis gas is collected into a first gas storage device (24); 4) The high-pressure low-oxygen concentration mixed gas (25) prepared by the mixing unit (15) and the first compressor (16) enters the second heat exchanger (18), exchanges heat with a mixture (43) of a pyrolysis product and supercritical CO 2 flowing out of the first production well (7) and the second production well (8), and enters the combustion input well (3) after being heated, the high Wen Meiceng (2) is subjected to in-situ controllable combustion under the oxidizing atmosphere, namely a controllable combustion reaction under an oxidizing gas heat supplementing path is started; 5) The superheated steam (33) is prepared by a water supply pump (29) and a boiler (30) in sequence, is injected into a coal bed (2) along a first heat injection well (4) and a second heat injection well (5) in a pulse mode, is subjected to gasification reaction with carbon deposition of pyrolysis products under the action of a catalyst bed (39), active hydrogen in the environment of the superheated steam (33) is filled to react with carbon deposition precursors, superheated steam mixed reaction products (44) flow out along a first production well (7) and a second production well (8) and then enter a third heat exchanger (31), circulating water (35) subjected to heat exchange and cooling enters the water supply pump (29), the above processes are circulated, and residual gas is collected into a second gas storage device (32); 6) The high-pressure water prepared by the water feeding pump exchanges heat with the high-temperature gas mixture (44) in the third heat exchanger (31), enters the boiler (30) after being preheated, is further heated to prepare superheated steam (33), and the superheated steam (33) is injected into the coal seam (2) along the first heat injection well (4) and the second heat injection well (5) in a pulse mode, and the above processes are repeated; 7) After the in-situ pyrolysis reaction of the oil-rich coal is finished, a large amount of semicoke products remain underground, superheated steam (33) is prepared in the same mode, the superheated steam is continuously injected into the stratum along the first heat injection well (4) and the second heat injection well (5), the semicoke products undergo gasification reaction, and gas products are collected into the second gas storage device (32).

Description

Multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system and method Technical Field The invention belongs to the technical field of energy, relates to a pyrolysis system and a pyrolysis method of oil-enriched coal, and in particular relates to an in-situ pyrolysis system and a method of oil-enriched coal with multifluid synergistic heat supply, coke inhibition and oil increase. Background In order to practically improve the oil gas yield and ensure the national energy safety, the in-situ pyrolysis technology of the oil-rich coal is developed. The technology provides a new path for exploitation and utilization of deep coal resources, but the technology currently faces a core bottleneck with low tar yield and serious in-situ loss. In the process of transferring tar products to a production well, secondary cracking and polycondensation reactions are very easy to occur, and carbon deposition which is difficult to utilize is generated. This not only results in reduced tar recovery and poor quality, but also the soot deposited in the pores and fissures can significantly reduce the permeability of the coal seam, and in severe cases even cause complete blockage of the oil and gas channels. Existing in-situ heating methods mainly include electrical heating and single fluid convection heating. When the electric heating is adopted, the heat transfer fluid is limited by extremely low heat conductivity coefficient of the coal bed, the heat conduction efficiency is poor, the heating period is long, when the single fluid convection heating is adopted, the heat transfer fluid has extremely high heat loss in long-distance transportation, and the huge heat absorption requirement of underground coal bed pyrolysis is difficult to meet, so that the heating efficiency is low and the energy consumption cost is huge. In addition, after the in-situ pyrolysis reaction is finished, a large amount of semicoke resources left underground cannot be effectively utilized, and huge waste of resources is also caused. At present, a synergistic regulation and control technology for in-situ pyrolysis of the oil-rich coal, which integrates efficient heat supply, coke inhibition and oil increase, pore dredging and semicoke utilization, is lacking. By utilizing the multi-fluid synergistic effect, the in-situ heating efficiency is enhanced, the secondary reaction of tar is effectively inhibited, the recycling utilization of semicoke is realized, and the urgent need of breaking through the technical bottleneck of in-situ exploitation of the rich oil coal is overcome. Therefore, the development of the multi-fluid collaborative heat supply and coke inhibition and oil increase rich coal in-situ pyrolysis system and method has very important practical significance. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a multi-fluid collaborative heat supply and coke inhibition and oil increase in-situ pyrolysis system and method for the oil-rich coal, which can obviously improve the tar yield, quality and energy utilization efficiency of in-situ exploitation of the oil-rich coal. The system comprises a combustion input well, a combustion output well, a first heat injection well, a first production well, a second heat injection well and a second production well which are excavated from the ground vertically downwards in a rich coal seam, wherein a middle horizontal well for communicating the combustion input well with the combustion output well, a lower horizontal well for communicating the first heat injection well with the first production well, and an upper horizontal well for communicating the second heat injection well with the second production well are excavated in the rich coal seam, a catalyst bed layer is paved at the positions, close to the coal seam, of the upper horizontal well and the lower horizontal well, the bottom end of the combustion input well is provided with an ignition device, heat preservation interlayers are respectively arranged outside the first production well and the second production well, independent fluid channels are formed between the heat preservation interlayers and the first production well and the second production well, annular nozzles are respectively arranged at fluid channel outlets at the lower ends of the first production well and the second production well, a liquid collecting pit is arranged at the bottom ends of the first production well and the second production well, and a heating element and a micro pump are arranged in the liquid collecting pit; The method comprises the steps of starting a controllable combustion reaction under an ignition heating path, heating the coal seam by using heat released by combustion to heat the coal seam at the upper and lower end areas, enabling high-temperature supercritical CO 2 to enter a first heat injection well and a second heat injection well, heating the coal seam along the