CN-117780323-B - Coal in-situ co-production system and method coupled with heat, chemistry and biology

CN117780323BCN 117780323 BCN117780323 BCN 117780323BCN-117780323-B

Abstract

The invention belongs to the technical field of oil-rich coal exploitation, and particularly discloses a coal in-situ combined coal exploitation system and method coupled with heat, chemistry and biology; the method comprises the steps of forming cracks in the horizontal well through hydraulic fracturing, injecting propping agents, dividing the underground coal bed into areas, arranging a packer connected with an electric heater at the junction of the areas, arranging branch pipelines in the injection well and the horizontal well, arranging a valve and a corresponding temperature sensor on each branch pipeline in each area of the horizontal well, introducing normal-temperature fluid into the injection well, opening the electric heater, expanding the packer at the moment, sealing the horizontal well, closing the electric heater after pyrolysis of the coal bed, introducing microbial aqueous solution, reducing the viscosity of a produced mixture by utilizing the degradation effect of microorganisms on polycyclic aromatic hydrocarbon and the emulsification effect on the water-oil mixture, effectively collecting tar adhered and retained on the walls of the coal bed and rocks, reducing the viscosity of the mixture, and improving the tar extraction rate.

Inventors

WU ZHIQIANG
Yang Panxi
GUO WEI
YU ZUNYI
WANG JING
LI HONGQIANG
YANG BOLUN
LI MINGJIE
WEI JINJIA

Assignees

西安交通大学

Dates

Publication Date: 20260508
Application Date: 20231229

Claims (10)

1. A thermo-chemical-biological coupled coal in situ co-production system comprising: The device comprises an injection well (5), a production well (6), a horizontal well (7), an electric heater (8), a packer (9) and a branch pipeline (10), wherein the electric heater (8) is positioned at one side close to the injection well (5), and the branch pipeline (10) is used for introducing a microbial solution containing nutrient substances; The injection well (5) and the extraction well (6) are both perpendicular to the underground coal seam (2), the injection well (5) and the extraction well (6) are arranged in parallel, the horizontal well (7) is arranged in parallel to the ground, one end of the horizontal well (7) is communicated with the bottom end of the injection well (5), and the other end of the horizontal well (7) is communicated with the bottom end of the extraction well (6); The underground coal seam (2) is divided into a plurality of areas along the horizontal direction, a valve (11) is arranged on the corresponding branch pipeline (10) in each area, a temperature sensor (12) corresponding to the valve (11) is arranged in each area, a packer (9) is arranged at an area junction (13) in the horizontal well (7), the electric heater (8) is connected with the packer (9), normal-temperature fluid is introduced into the horizontal well (7) from the injection well (5), when the electric heater (8) is started, the packer (9) can expand at the high temperature of the electric heater (8), the area junction (13) is closed, the normal-temperature fluid is heated to be high-temperature fluid through the electric heater (8), and oil gas products are released by pyrolysis.
2. A thermo-chemical-biological coupled coal in situ co-production system according to claim 1, characterised in that the packer (9) is connected to the electric heater (8) in horizontal direction, the packer (9) being located on the side close to the production well (6).
3. The thermally-chemically-biologically coupled coal in-situ co-production system of claim 1 wherein each zone has a length of 10-20m.
4. The coal in-situ combined production system coupling heat, chemistry and biology according to claim 1 is characterized in that two parallel through horizontal wells (7) are arranged between an injection well (5) and a production well (6), the two parallel horizontal wells (7) are respectively arranged at the middle part and the bottom of an underground coal seam (2), branch pipelines (10) are arranged in the injection well (5) and the two horizontal wells (7), a valve (11) is arranged in each area of the two horizontal wells (7) in the branch pipelines (10), a temperature sensor (12) corresponding to the valve is arranged, and a packer (9) connected with an electric heater (8) is respectively arranged at a junction (13) of the area in each horizontal well (7).
5. The coal in-situ co-production system coupled with heat, chemistry and biology according to claim 1, wherein a gas heater (16) is installed at the inlet of the horizontal well (7), a stratum temperature sensor (14) is installed in the horizontal well (7), and the production well (6) is connected with a gas concentration detector (15).
6. A coal in situ co-production method coupled with heat-chemistry-biology, which is characterized in that the coal in situ co-production system coupled with heat-chemistry-biology according to any one of claims 1 to 5 comprises: Drilling an injection well (5) and a production well (6) from the ground surface to the underground coal bed (2), and drilling a horizontal well (7) penetrating between the injection well (5) and the production well (6); Injecting fracturing agent into the underground coal bed (2) from an injection well (5) to carry out hydraulic fracturing, forming a crack (4) in the underground coal bed (2), and injecting propping agent; Laying branch pipelines (10) in an injection well (5) and a horizontal well (7), wherein the branch pipelines (10) are provided with a valve (11) and a temperature sensor (12) corresponding to the valve (11) in each area in the horizontal well (7); Introducing normal-temperature fluid into the horizontal well (7) from the injection well (5), and simultaneously starting the electric heater (8), wherein the packer (9) expands at the high temperature of the electric heater (8) to seal the junction (13) of the area; After the coal in the first area is completely pyrolyzed, the electric heater (8) is turned off, the temperature of the packer (9) is reduced, the sealing of the horizontal well (7) is released, and oil gas products are collected to the ground through the extraction well (6); Pushing the packer (9) to the junction of the second area and the third area, restarting the electric heater (8), and sealing and pyrolyzing the coal bed in the second area; The temperature of each area is detected by a temperature sensor (12), a valve (11) in the first area is opened, a microorganism water solution with nutrient substances is introduced, cracks in the first area are washed, residual tar products are extracted, and part of tar products and oil gas products in the second area flow out of a production well (6) together and are collected; repeating the steps until pyrolysis and tar collection are completed in all coal seam areas.
7. The method for in-situ co-production of coal coupled with heat, chemistry and biology according to claim 6, wherein the introduced normal temperature fluid is nitrogen or carbon dioxide.
8. The in-situ coal co-production method for coupling heat, chemistry and biology according to claim 6, wherein the valve (11) on the branch pipeline (10) is controlled by a corresponding temperature sensor (12), when the temperature sensor (12) in the area monitors that the temperature of the coal bed in the area is lower than the tolerable temperature of microorganisms, the corresponding valve (11) is opened, and when the temperature in the next area is also lower than the tolerable temperature of microorganisms, the valve (11) is closed, and the corresponding valve (11) in the next area is opened.
9. The method of in situ co-production of coal coupled to thermo-chemical-biological according to claim 6, wherein the microorganism tolerant temperature is between 30 ℃ and 50 ℃.
10. The method for in-situ co-production of coal coupled with heat, chemistry and biology according to claim 6, wherein the microorganism is Pseudomonas aeruginosa, and the nutrient substance comprises a carbon source, a nitrogen source and a phosphorus source.

Description

Coal in-situ co-production system and method coupled with heat, chemistry and biology Technical Field The invention belongs to the technical field of oil-rich coal exploitation, and particularly relates to a coal in-situ combined exploitation system and method for coupling heat, chemistry and biology. Background The in-situ pyrolysis of underground coal is used as an emerging coal utilization technology, has the advantages of small ground pollution, low carbon emission, large mining depth, avoidance of surface subsidence and the like, and has been applied to oil shale to obtain preliminary results, and the in-situ pyrolysis of the underground coal has good development prospect for extracting oil and gas resources. In the underground in-situ pyrolysis process of the oil-rich coal, products produced by pyrolysis are firstly collected into a horizontal well and then flow into a production well under the carrying of hot carrier gas. However, a large amount of heavy aromatic hydrocarbon components exist in tar products of coal pyrolysis, and the tar products have the adverse characteristics of high molecular weight, high viscosity and easy coking, so that the heavy components are easy to stay and block cracks in a coal bed, transport of oil and gas products is hindered, and the product yield is reduced. Aiming at the technical problem that heavy components of tar are easy to coagulate, the current research mostly considers that the fluidity and the availability of a product mixture are ensured by reasonably regulating and controlling the external temperature and the external pressure from the state equation and the viscosity-temperature curve of tar substances. However, the in-situ pyrolysis process in actual ground has complex mechanism, the actual ground working condition and the prediction reliability of the product precipitation and transportation conditions are difficult to ensure, and therefore, the recovery ratio cannot be improved by only physically regulating and controlling the product. Disclosure of Invention The invention aims to provide a coal in-situ combined production system and method coupled with heat, chemistry and biology, which are used for solving the problems that tar products of coal pyrolysis are easy to stay and block cracks in a coal bed, transport is blocked, and the production rate of the products is reduced. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: In a first aspect, the invention provides a thermally-chemically-biologically coupled coal in situ co-production system comprising: The device comprises an injection well, a production well, a horizontal well, an electric heater, a packer and branch pipelines, wherein the electric heater is positioned at one side close to the injection well, the branch pipelines are used for introducing microorganism solution containing nutrient substances, the injection well and the production well are both arranged perpendicular to an underground coal seam, the injection well and the production well are arranged in parallel, the horizontal well is arranged parallel to the ground, one end of the horizontal well is communicated with the bottom end of the injection well, the other end of the horizontal well is communicated with the bottom end of the production well, the branch pipelines are arranged in the injection well and the horizontal well, the underground coal seam is divided into a plurality of areas along the horizontal direction, a valve is arranged on the branch pipeline corresponding to each area, a temperature sensor corresponding to the valve is arranged in each area, the packer is arranged at the junction of the area in the horizontal well, the electric heater is connected with the packer, normal temperature fluid is introduced into the horizontal well from the injection well, when the electric heater is started, the packer can expand at the high temperature of the electric heater, the junction of the area is sealed, the normal temperature fluid is heated to be high temperature fluid through the electric heater, and the thermal coal seam is pyrolyzed, and oil gas products are released. Further, the packer is connected with the electric heater in the horizontal direction, and the packer is positioned at one side close to the production well. Further, the length of each region is 10-20m. Furthermore, two parallel through horizontal wells are arranged between the injection well and the extraction well, the two parallel horizontal wells are respectively arranged at the middle part and the bottom of the underground coal seam, branch pipelines are arranged in the injection well and the two horizontal wells, a valve is arranged in each area of the two horizontal wells, a temperature sensor corresponding to the valve is arranged in each area of the two horizontal wells, and a packer connected with an electric heater is respectively arranged at the junction of the areas in each horizo