Method for efficiently recovering natural gas based on one-roadway dual-purpose and three-gas commingling production

Abstract

The invention discloses a method for efficiently recovering natural gas based on one-roadway dual-purpose and three-gas commingling production, and belongs to the technical field of natural gas hydrate production. According to the method, the one-roadway dual-purpose and three-gas commingling mining technology is combined with the microwave fracturing decomposition promoting and permeability increasing technology, on one hand, a long-term stable working roadway is arranged in a coal measure stratum, and synchronous mining of three natural gas resources of tight sandstone gas, coal bed gas and shale gas is achieved; according to the microwave fracturing decomposition promoting and permeability increasing technology, the rock stratum is heated through high-frequency electromagnetic waves, the permeability is improved, and efficient release of natural gas is promoted. On the other hand, the permeability of rocks is improved, release of natural gas is promoted, the gas permeability of the reservoir is improved by 107-266%, meanwhile, efficient desorption / release of natural gas in the coal reservoir is promoted, and water resource consumption, secondary geological disasters and environmental pollution are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas hydrate exploitation, and in particular relates to a method for efficiently recovering natural gas based on dual-use of one tunnel and three-gas combined exploitation. Background Art

[0002] As global energy demand continues to increase, natural gas, as a clean and efficient energy source, has attracted widespread attention for its extraction technology. Traditional extraction methods such as hydraulic fracturing have been widely used, but traditional natural gas extraction requires the deployment of a fleet of pump trucks on the ground for hydraulic fracturing, and there are problems such as environmental pollution and high water consumption. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production, comprising the following steps:

[0006] (1) A working tunnel is opened in a stable rock layer of a coal-bearing stratum, the working tunnel leads to the ground, and a first extraction pipeline is arranged inside the working tunnel;

[0007] (2) In the working tunnel, blind wells are opened upward and downward respectively to connect the working tunnel, a Teflon protective pipe is placed in the blind well, a second extraction pipeline and a microwave heating antenna are located inside the Teflon protective pipe, an end of the microwave heating antenna is connected to a microwave heating transmitting device, the blind well above the working tunnel and the internal Teflon protective pipe upwardly penetrate the dense sandstone layer and extend into the shale layer, and the blind well below the working tunnel and the internal Teflon protective pipe downwardly penetrate the bending zone and extend into the fracture zone; through holes are distributed on the surface of the Teflon protective pipe; the second extraction pipeline is connected to the first extraction pipeline;

[0008] (3) During the coal mining process, the second extraction pipeline located above the working tunnel and the microwave heat injection transmitting device are located in the shale layer, the microwave heat injection transmitting device performs microwave heat injection, the pump connected to the second extraction pipeline is turned on, and the second extraction pipeline extracts shale layer gas; then the second extraction pipeline located above the working tunnel and the microwave heat injection transmitting device are located in the dense sandstone layer, the microwave heat injection transmitting device performs microwave heat injection, the pump connected to the second extraction pipeline is turned on, and the second extraction pipeline extracts the dense sandstone layer gas, and the extracted shale layer gas and dense sandstone layer gas are transported to the first extraction pipeline and then transported to the ground;

[0009] (4) While exploiting shale gas, the second extraction pipeline located below the working tunnel and the microwave heat injection transmitting device are located in the fracture zone, the microwave heat injection transmitting device performs microwave heat injection, and the pump connected to the second extraction pipeline is turned on. The second extraction pipeline extracts coalbed methane and transports it to the first extraction pipeline and then to the ground; then the second extraction pipeline located below the working tunnel and the microwave heat injection transmitting device are located in the bending zone, the microwave heat injection transmitting device performs microwave heat injection, and the pump connected to the second extraction pipeline is turned on. The second extraction pipeline extracts dense sandstone gas and transports it to the first extraction pipeline and then to the ground.

[0010] The microwave heat injection transmitting device used in the present invention is a conventional microwave heat injection transmitting device in the art, and the microwave heat injection parameters can be selected and set according to actual needs.

[0011] As a preferred embodiment of the present invention, the number of blind shafts opened upward in the working tunnel is more than 2; the number of blind shafts opened downward in the working tunnel is more than 2, and the blind shafts are arranged according to actual needs.

[0012] As a preferred embodiment of the present invention, in step (3), a blind shaft is set above the coal mining area, and shale gas, tight sandstone gas and coalbed methane are mined simultaneously during the coal mining process.

[0013] As a preferred embodiment of the present invention, the second extraction pipeline is composed of a plurality of pipelines which are detachably connected end to end. During the mining of dense sandstone layers, the port of the second extraction pipeline is placed in the mining area by disassembling part of the pipeline of the second extraction pipeline; the end of the microwave heat injection antenna is connected to the microwave heat injection transmitting device, and the wire is bendable so as to control the position of the microwave heat injection transmitting device.

[0014] As a preferred embodiment of the present invention, the end of the second extraction pipeline and the microwave heat injection emission equipment are in the same mining area.

[0015] As a preferred embodiment of the present invention, the first extraction pipeline and the second extraction pipeline are both connected to pumps to collect the extracted gas from the mining area into the second extraction pipeline, and then transport it to the ground through the first extraction pipeline.

[0016] As a preferred embodiment of the present invention, a sealer is provided inside the Teflon protective tube, and the sealer is connected to the Teflon protective tube with a gap fit to divide the Teflon protective tube into two parts, the first extraction pipeline and the microwave heating antenna pass through the sealer inside the Teflon protective tube.

[0017] The gap-fit ​​connection between the hole sealer and the Teflon protective tube is to create a closed environment for the extraction pipeline. The negative pressure environment formed is conducive to the extraction of natural gas by the extraction pipeline.

[0018] As a preferred embodiment of the present invention, when the second extraction pipeline is located in a shale layer to extract shale gas, the sealer is located in the mudstone layer; when the second extraction pipeline is located in a dense sandstone layer to extract dense sandstone gas, the sealer is located at the bottom of a blind well; when the second extraction pipeline is located in a fracture zone to extract coalbed methane, the sealer is located in a curved zone.

[0019] As a preferred embodiment of the present invention, the microwave heat injection transmitting equipment performs microwave heat injection 3-4 times in the shale layer; the microwave heat injection transmitting equipment performs microwave heat injection 2-3 times in the dense sandstone layer; the microwave heat injection transmitting equipment performs microwave heat injection 1-2 times in the curved zone; and the microwave heat injection transmitting equipment performs microwave heat injection 1-2 times in the fracture zone.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes for the first time to combine the one-lane dual-use, three-gas co-production technology with microwave fracturing technology. On the one hand, by laying a long-term and stable working lane in the coal-bearing strata, the simultaneous exploitation of three natural gas resources, namely, tight sandstone gas, coalbed methane and shale gas, is achieved, reducing the demand for multi-well development and improving resource utilization efficiency; at the same time, the coalbed gas is effectively controlled to reduce the probability of gas outburst disasters during coal mining. On the other hand, the permeability of the rock is improved, the release of natural gas is promoted, the reservoir gas permeability is increased by 107-266%, and the efficient desorption / release of natural gas in the coal reservoir is promoted, the natural gas recovery rate is increased by more than 30%, and water resource consumption, secondary geological disasters and environmental pollution are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the efficient recovery of natural gas by three-gas combined production according to the present invention.

[0022] Figure 2 This is a schematic diagram of the second extraction pipeline. DETAILED DESCRIPTION

[0023] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0024] The coal-bearing strata in the present invention include coal seams, fracture zones, curved zones, dense sandstone layers, mudstone and shale layers from bottom to top.

[0025] Example 1

[0026] A method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production, comprising the following steps:

[0027] (1) Figure 1 As shown, a system for efficient recovery of natural gas from three-gas combined production is established:

[0028] S1: A working tunnel is opened in the stable rock layer above the curved subsidence zone of the coal-bearing stratum. The tail end of the working tunnel leads to the ground. A first extraction pipeline is arranged inside the working tunnel. The first extraction pipeline leads to the ground along the working tunnel. The ground end of the first extraction pipeline is connected to an extraction pump 1 to transport the extracted natural gas to the ground for collection.

[0029] S2: In the working tunnel above the area where the coal is being mined, blind shafts are opened upward and downward to connect the working tunnels, so as to realize the simultaneous mining of coal, shale gas, tight sandstone gas and coalbed methane. The Teflon protective pipe is placed in the blind shaft, and the length of the Teflon protective pipe is consistent with the length of the blind shaft. Figure 2 As shown, the second extraction pipeline and the microwave heating antenna are located inside the Teflon protective tube. The second extraction pipeline is composed of a plurality of pipelines connected detachably at the head and tail. The tail of the second extraction pipeline is connected to the first extraction pipeline. In the process of extracting shale gas, tight sandstone gas and coalbed methane, the port of the second extraction pipeline is placed in the extraction area (i.e., shale layer, tight sandstone layer or fracture zone) by disassembling part of the second extraction pipeline. The blind shaft above the working lane and the internal Teflon protective tube penetrate upward through the tight sandstone layer and extend into the shale layer. The blind shaft below the working lane and the internal Teflon protective tube penetrate downward through the bending zone and extend into the fracture zone. Through holes are distributed on the surface of the Teflon protective tube. A sealer is arranged inside the Teflon protective tube. The sealer and the Teflon protective tube are in gap coordination to divide the Teflon protective tube into two parts, the first extraction pipeline and the microwave heating antenna penetrate the sealer inside the Teflon protective tube. The second extraction pipeline is located at one end of the first extraction pipeline and is connected to the extraction pump 2.

[0030] (2) During the coal mining process, the second extraction pipeline located above the working tunnel and the microwave heat injection transmitting equipment are located in the shale layer, the hole sealer is located in the mudstone layer, the microwave heat injection transmitting equipment performs microwave heat injection, and the extraction pump 2 connected to the second extraction pipeline is turned on. The shale gas in the shale layer enters the Teflon protective pipe through the through holes distributed on the surface of the Teflon protective pipe, and then enters the second extraction pipeline through the second extraction pipeline port.

[0031] (3) When the extraction output cannot meet the designed mining output, the extraction layer is replaced, so that the tight sandstone gas is mined after the shale gas extraction is completed. Part of the second extraction pipeline located above the working tunnel is dismantled and the port of the second extraction pipeline is placed in the tight sandstone layer mining area. The microwave heat injection transmitter located above the working tunnel is located in the tight sandstone layer, and the sealer is located at the bottom of the blind well. The microwave heat injection transmitter performs microwave heat injection, and the extraction pump 2 connected to the second extraction pipeline is continuously turned on. The second extraction pipeline extracts the tight sandstone gas in the tight sandstone layer. The tight sandstone gas enters the Teflon protective pipe through the through holes distributed on the surface of the Teflon protective pipe, and then enters the second extraction pipeline and the first extraction pipeline through the port of the second extraction pipeline. The extracted shale gas and tight sandstone gas are transported to the first extraction pipeline through the extraction pump 2 and then transported to the ground.

[0032] (4) While extracting shale gas, the second extraction pipeline and microwave heat injection transmitter located below the working tunnel are located in the fracture zone, the hole sealer is located in the bending zone, the microwave heat injection transmitter performs microwave heat injection, and the extraction pump 2 connected to the second extraction pipeline is turned on. The gas released in the coal seam enters the Teflon protective tube through the fractures in the fracture zone and through the through holes distributed on the surface of the Teflon protective tube, then enters the second extraction pipeline, and finally merges into the first extraction pipeline and is transported to the ground, thereby achieving the purpose of extracting gas. After the coal seam mining is completed, the coal seam gas extraction is also completed. The second extraction pipeline and microwave heat injection transmitter located below the working tunnel are moved upward to the bending zone, the hole sealer is located at the top of the blind shaft, the microwave heat injection transmitter performs microwave heat injection, and the extraction pump 2 connected to the second extraction pipeline is turned on. The dense sandstone layer gas released in the bending zone enters the Teflon protective tube through the through holes distributed on the surface of the Teflon protective tube, then enters the second extraction pipeline, and finally merges into the first extraction pipeline and is transported to the ground.

[0033] Compared with traditional hydraulic fracturing, the present invention combines the dual-purpose of one lane and three-gas combined production technology with microwave fracturing technology to improve the permeability of rocks and promote the release of natural gas. The reservoir gas permeability is increased by 107-266%, while promoting the efficient analysis / release of natural gas in coal reservoirs, reducing water resource consumption, secondary geological disasters and environmental pollution.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production, characterized in that: The steps include: (1) A working tunnel is opened in a stable rock layer of a coal-bearing stratum, the working tunnel leads to the ground, and a first extraction pipeline is arranged inside the working tunnel; (2) In the working tunnel, blind wells are opened upward and downward respectively to connect the working tunnel, a Teflon protective pipe is placed in the blind well, a second extraction pipeline and a microwave heating antenna are located inside the Teflon protective pipe, an end of the microwave heating antenna is connected to a microwave heating transmitting device, the blind well above the working tunnel and the internal Teflon protective pipe upwardly penetrate the dense sandstone layer and extend into the shale layer, and the blind well below the working tunnel and the internal Teflon protective pipe downwardly penetrate the bending zone and extend into the fracture zone; through holes are distributed on the surface of the Teflon protective pipe; the second extraction pipeline is connected to the first extraction pipeline; (3) During the coal mining process, the second extraction pipeline located above the working tunnel and the microwave heat injection transmitting device are located in the shale layer, the microwave heat injection transmitting device performs microwave heat injection, the pump connected to the second extraction pipeline is turned on, and the second extraction pipeline extracts shale layer gas; then the second extraction pipeline located above the working tunnel and the microwave heat injection transmitting device are located in the dense sandstone layer, the microwave heat injection transmitting device performs microwave heat injection, the pump connected to the second extraction pipeline is turned on, and the second extraction pipeline extracts the dense sandstone layer gas, and the extracted shale layer gas and dense sandstone layer gas are transported to the first extraction pipeline and then transported to the ground; (4) While exploiting shale gas, the second extraction pipeline located below the working tunnel and the microwave heat injection transmitting device are located in the fracture zone, the microwave heat injection transmitting device performs microwave heat injection, and the pump connected to the second extraction pipeline is turned on. The second extraction pipeline extracts coalbed methane and transports it to the first extraction pipeline and then to the ground; then the second extraction pipeline located below the working tunnel and the microwave heat injection transmitting device are located in the bending zone, the microwave heat injection transmitting device performs microwave heat injection, and the pump connected to the second extraction pipeline is turned on. The second extraction pipeline extracts dense sandstone gas and transports it to the first extraction pipeline and then to the ground.

2. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1 is characterized in that: In the step (3), a blind shaft is set above the coal mining area, and shale gas, tight sandstone gas and coalbed methane are mined simultaneously during the coal mining process.

3. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1, characterized in that: The second extraction pipeline is composed of a plurality of pipelines that are detachably connected end to end. During the mining of dense sandstone layers, the port of the second extraction pipeline is placed in the mining area by disassembling part of the pipeline.

4. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1, characterized in that: The end of the second extraction pipeline and the microwave heat injection transmitting equipment are in the same mining area.

5. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1, characterized in that: The first extraction pipeline and the second extraction pipeline are both connected to pumps to collect the extracted gas from the mining area into the second extraction pipeline, and then transport it to the ground through the first extraction pipeline.

6. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1, characterized in that: A hole sealer is arranged inside the Teflon protective tube, and the hole sealer is connected with the Teflon protective tube with a gap fit to divide the Teflon protective tube into two parts, the first extraction pipeline and the microwave heating antenna pass through the hole sealer inside the Teflon protective tube.

7. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 6, characterized in that: When the second extraction pipeline is located in the shale layer to extract shale gas, the sealer is located in the mudstone layer; when the second extraction pipeline is located in the tight sandstone layer to extract tight sandstone gas, the sealer is located at the bottom of the blind well; when the second extraction pipeline is located in the fracture zone to extract coalbed methane, the sealer is located in the curved zone.

8. The method for efficiently recovering natural gas based on dual-use of one lane and three-gas combined production as claimed in claim 1, characterized in that: The microwave heat injection transmitting equipment carries out 3-4 microwave heat injections in the shale layer; the microwave heat injection transmitting equipment carries out 2-3 microwave heat injections in the dense sandstone layer; the microwave heat injection transmitting equipment carries out 1-2 microwave heat injections in the curved zone; the microwave heat injection transmitting equipment carries out 1-2 microwave heat injections in the fracture zone.

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