Method for fracture communication, passage processing, and underground gasification of underground carbon-containing organic mineral reservoir

Abstract

Provided is a method for fracture communication, passage processing and underground gasification of an underground carbon-containing organic mineral reservoir, where a mixture of CO 2 and O 2 is used as a medium for a fracture communication step, a passage processing step and/or a gasification step. The method uses the mixture of CO 2 and O 2 to extract and utilize the energy in the underground carbon-containing organic mineral reservoir, greatly increases energy utilization efficiency compared with conventional utilization schemes, and, compared with conventional underground gasification technologies, increases the calorific value of a combustible gas, increases and adjusts effective gas compositions, suppresses CO 2 generation and reduces raw material gas production costs, while at the same time implements the capturing of CO 2 and utilization of the same as a resource.

1 . A method wherein a mixture of CO 2  and O 2  is in injected into an underground carbon-containing organic mineral reservoir through an injection borehole whereby said injected mixture effects fracture communication or passage processing. 
     
     
         2 . A method for fracture communication of an underground carbon-containing organic mineral reservoir, wherein the carbon-containing organic mineral reservoir is provided with at least one injection borehole and at least one production borehole, which allow the carbon-containing organic mineral reservoir to communicate with the ground, respectively, characterized in that, the method comprises: injecting a mixture of CO 2  and O 2  as a fracturing medium through the injection borehole to form a communicating fracture in the carbon-containing organic mineral reservoir between the injection borehole and the production borehole. 
     
     
         3 . A method for gasification passage processing of an underground carbon-containing organic mineral reservoir, wherein the carbon-containing organic mineral reservoir is provided with at least one injection borehole and at least one production borehole, which allow the carbon-containing organic mineral reservoir to communicate with the ground, respectively, and a communicating fracture has been formed in the carbon-containing organic mineral reservoir between the injection borehole and the production borehole, characterized in that, the method comprises: processing the communicating fracture by using a mixture of CO 2  and O 2  as a passage processing medium, and expanding the communicating fracture by pressurization and/or combustion to form a gasification passage, 
     
     
         4 . A method for underground gasification of an underground carbon-containing organic mineral reservoir, wherein the carbon-containing organic mineral reservoir Is provided with at least one injection borehole and at least one production borehole, which allow the carbon-containing organic mineral reservoir to communicate with the ground, respectively, characterized in that, the method for underground gasification comprises: a fracture communication step of performing fracture communication to the carbon-containing organic mineral reservoir to form a communicating fracture; a passage processing step of performing passage processing to the communicating fracture to form a gasification passage; and a gasification step of gasifying the underground carbon-containing organic mineral reservoir to generate a raw gas, where a mixture of CO 2  and O 2  is used as a medium in at least one step in the group of the fracture communication step, the passage processing step and the gasification step. 
     
     
         5 . The method according to  claim 4 , characterized in that, the injection borehole is a directional boreholes or vertical borehole and carbon-containing material is recovered from the reservoir through a directional or vertical production borehole. 
     
     
         6 . The method according to  claim 4 , characterized in that, after the fracture communication step, the carbon-containing organic mineral reservoir is ignited to establish a fire zone, and the passage processing step and the gasification step are then performed. 
     
     
         7 . The method according to  claim 4 , characterized in that, before the fracture communication step, a fire zone has been established in the carbon-containing organic mineral reservoir, and the fracture communication step, the passage processing step and the gasification step are performed by using the existed fire zone of the carbon-containing organic mineral reservoir. 
     
     
         8 . The method according to  claim 4 , characterized in that, in the fracture communication, step, by injecting a mixture of CO 2  and O 2  as a fracturing medium from the injection borehole, the communicating fracture, is formed in the carbon-containing organic mineral reservoir between the injection borehole and the production borehole. 
     
     
         9 . The method according to  claim 4 , characterized in that, in the passage processing step, by using a mixture of CO 2  and O 2  as a passage processing medium, the communicating fracture is expanded by pressurization and/or combustion to form the gasification passage. 
     
     
         10 . The method according to  claim 4 , characterized in that, in the gasification step, a combustion reaction is performed while increasing the inflow of a mixture of CO 2  and O 2  as a gasification medium in the gasification passage, so that the carbon-containing organic mineral reservoir is gasified to generate the raw gas. 
     
     
         11 . The application or method according to  claim 4 , characterized in that, the carbon-containing organic mineral reservoir is a coal seam or an oil shale layer. 
     
     
         12 . The method according to  claim 4 , characterized in that, in the fracture communication step, the carbon-containing organic mineral reservoir between the injection borehole and the production borehole is fractured by mechanical drilling, and then the medium is injected to form the communicating fracture. 
     
     
         13 . The method according to  claim 12 , characterized in that, the mechanical drilling is at least one drilling in the group of directionally horizontal drilling, ultrashort-radius horizontal drilling and pinnate horizontal drilling. 
     
     
         14 . The method according to  claim 4 , characterized in that, during the fracture communication, pressure changes in the injection borehole and in the production borehole are monitored: and, when the pressure in the injection borehole drops sharply while the gas outflow of the production borehole is above 100 Nm 3 /h, it indicates that the communicating fracture has been formed. 
     
     
         15 . The method according to  claim 1 , characterized in that, the volume concentration of O 2  in the medium for the fracture communication and/or the passage processing is 20-50%. 
     
     
         16 . The method according to  claim 15 , characterized in that, the volume concentration of O 2  in the medium for the fracture communication, and/or the passage processing is 20-35%. 
     
     
         17 . The method according to  claim 4 . characterized in that, the volume concentration of O 2  in the medium for the gasification step is 50-70%. 
     
     
         18 . The underground gasification method according to  claim 4 , characterized in that, the volume concentration of O 2  in the medium for the gasification step is 50-65%. 
     
     
         19 . The underground gasification method according to  claim 4 , characterized in that, further comprises:
 a CO 2  recycling step: separating and recycling CO 2  from the raw gas generated in the gasification step, wherein at least one part of the recycled CO 2  is pressurized and then injected into the carbon-containing organic mineral reservoir for the fracture communication, the passage processing and/or the gasification.   
     
     
         20 . The underground gasification method according to  claim 19 , characterized in that, further comprises:
 a CO 2  storage step: injecting the recycled CO 2  into the combustion cavity generated after gasifying the carbon-containing organic mineral reservoir for storage.   
     
     
         21 . The method according to  claim 1 , characterized in that the CO 2  in the medium Is gaseous, liquid or supercritical CO 2 . 
     
     
         22 . The method according to  claim 1 , characterized in that, the CO 2  in the medium is a mixed liquid composed of liquid CO 2 , collagen liquid and chemical additives. 
     
     
         23 . The method according to  claim 4 , characterized in that, solid-phase particles are added into the medium to support the formed communicating fracture. 
     
     
         24 . The method according to  claim 4 , characterized in that, the mixture of CO 2  and O 2  is obtained by mixing CO 2  with pure oxygen on the ground or in the injection borehole. 
     
     
         25 . The method according to  claim 4 , characterized in that, a fire zone is established at the bottom of the injection borehole or the production borehole, and the mixture of CO 2  and O 2  is conveyed from the ground to the fire zone through an annular conveying pipe or the injection borehole. 
     
     
         26 . The method according to  claim 4 , characterized in that, a high pressure pipeline for conveying the mixture of CO 2  and O 2  or for feeding high pressure CO 2  during the CO 2  storage step at the end of gasification and a low pressure pipeline for conveying the low pressure mixture of CO 2  and O 2  are mounted at the inlet of the injection borehole, and a high pressure coal gas pipeline for conveying a gas mixture generated during the fracture communication and a low pressure coal gas pipeline for conveying the low pressure raw gas generated by the gasification are mounted at the outlet of the production borehole. 
     
     
         27 . The method according to  claim 4 , characterized in that, CO 2  in the generated raw gas is separated and captured, and the captured CO 2  is used for the fracture communication, the passage processing or the underground gasification. 
     
     
         28 . The method according to  claim 4 , characterized in that, the medium further comprises water vapor. 
     
     
         29 . The method according to  claim 4 , characterized in that the volume concentration of O2 in the medium for the fracture communication and/or passage processing is 20-50%. 
     
     
         30 . The method according to  claim 4  characterized in that the medium is a mixed liquid composed of liquid CO2, collagen, liquid and chemical additives.