Integrated method and structure for in-situ hydrogen production from coal seams and coalbed methane exploitation

Abstract

The application discloses an integrated method and structure for in-situ hydrogen production from coal seams and coalbed methane exploitation, belonging to the technical field of energy exploitation. The method comprises: injecting gasification agent through an injection well, exploiting coalbed methane and gasification gas through a production well. The injection well is a stepped horizontal well, the injection well is provided with at least one, and the projections of the horizontal sections of any two injection wells in the vertical direction do not overlap. At least one horizontal section of the stepped horizontal well is arranged in any coal seam to be mined. The method of the present application avoids the large-area continuous gasification of a single coal seam and the repeated position gasification of overlapping multiple coal seams, reduces the change range and degree of formation stress, disperses the underground void volume, reduces the risk of formation or ground collapse.

What is claimed is: 
     
         1 . An integrated method for in-situ hydrogen production from coal seams and coalbed methane exploitation, comprising the following steps:
 injecting gasification agent through an injection well, and exploiting coalbed methane and gasification gas through a production well;   wherein the injection well is configured to be a stepped horizontal well, the injection well is provided with at least one, and the projections of the horizontal sections of any two injection wells in the vertical direction do not overlap, and at least one horizontal section of the stepped horizontal well is arranged in any coal seam to be mined.   
     
     
         2 . The method according to  claim 1 , wherein the production well is configured to be a cluster well, and a directional well or a first vertical well of the cluster well is configured to pass through all the coal seams to be mined. 
     
     
         3 . The method according to  claim 1 , wherein the production well is a combination of a plurality of second vertical wells or inclined wells, and the second vertical wells or inclined wells are configured to pass through all the coal seams to be mined. 
     
     
         4 . The method according to  claim 2 , wherein in any of the horizontal sections, a vertical well or inclined well passing through the coal seam to be mined where the horizontal section is located is provided in the coal gasification range of the horizontal section, and the horizontal section communicates or does not communicate with its adjacent vertical well or inclined well. 
     
     
         5 . The method according to  claim 3 , wherein in any of the horizontal sections, a vertical well or inclined well passing through the coal seam to be mined where the horizontal section is located is provided in the coal gasification range of the horizontal section, and the horizontal section communicates or does not communicate with its adjacent vertical well or inclined well. 
     
     
         6 . The method according to  claim 1 , wherein before injecting the gasification agent into the injection well and exploiting the coalbed methane and gasification gas through the production well, the method further comprises: draining water from the coal seam through the production well. 
     
     
         7 . The method according to  claim 1 , wherein multi-layered coal seams to be mined are simultaneously injected with a gasification agent and gasified simultaneously; or, starting from the lowest coal seam to be mined, the gasification agent is injected upward layer by layer and gasified in stages. 
     
     
         8 . The method according to  claim 1 , wherein after injecting gasification agent into the injection well, and after exploiting coalbed methane and gasified gas in the production well, the method also comprises: carrying out carbon dioxide separation on the ground from the mined coalbed methane and gasification gas, and injecting separated carbon dioxide into a target coal seam. 
     
     
         9 . The method according to  claim 8 , wherein the carbon dioxide is injected into the target coal seam through an injection well far from the horizontal section in the target coal seam. 
     
     
         10 . A structure for in-situ hydrogen production from coal seams and coalbed methane exploitation, comprising:
 an injection well, which is provided with at least one and is configured to be a stepped horizontal well, wherein the projections of the horizontal sections of any two injection wells in the vertical direction do not overlap, and at least one horizontal section of the stepped horizontal well is arranged in any coal seam to be mined;   a production well, which is configured to pass through all the coal seams to be mined, and for any horizontal section of the injection well, there is a production well that passes through the coal gasification range of the coal seam where the horizontal section is located.   
     
     
         11 . The structure according to  claim 10 , wherein, the production well is configured to be a cluster well, and a directional well or a first vertical well of the cluster well is configured to pass through all the coal seams to be mined; or, the production well is a combination of a plurality of second vertical wells or inclined wells, and the second vertical wells or inclined wells are configured to pass through all the coal seams to be mined.