In-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane

Abstract

An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane is provided, which includes: constructing an injection well to the target coal seam and then constructing a horizontal well to divide the target coal seam into sections of coal; extracting coalbed methane; transforming the horizontal wells on both sides of the coal in the first section of coal into coal gasification production wells, and dividing them into intake and exhaust channels; constructing ventilation boreholes to form a “honeycomb shaped” gasifier, which ignites and gasifies to promote the production of combined gases from combustion; after the combustion of first section of coal is completed, continuing to construct the next section of coal and drill holes between adjacent horizontal wells to achieve continuous coal seam combustion and gasification. The method of the present disclosure can improve combustion efficiency and increase kerosene extraction efficiency.

What is claimed is: 
     
         1 . An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane, applied to a single coal seam, comprising the following steps:
 step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal;   step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO 2  injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both an oil transportation well and a coalbed methane transportation well; injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing of the oil-bearing coal seam in the first section of coal, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation well; for coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation well, and the coalbed methane is slowly released and collected through the coalbed methane transportation well;   step 3, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells;   step 4, after the combustion of the first section of coal is completed, carrying out a mining of a second section of coal in sequence according to step 2 and step 3 to achieve continuous combustion and gasification of the coal seam.   
     
     
         2 . The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane according to  claim 1 , wherein in step 2, constructing the first horizontal well based on a position of the first section of coal and an injection well layout plan;
 arranging pipeline for cracking oil displacement-coalbed methane extraction systems inside the first horizontal well and the second horizontal well, respectively.   
     
     
         3 . The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane according to  claim 1 , wherein in step 3, the ventilation boreholes are perpendicular to the coal gasification production well and parallel to the coal seam of the first section of coal. 
     
     
         4 . The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane according to  claim 1 , wherein in step 3, it further comprises an ignition device; using the ignition device to ignite the input gasification agent in the coal gasification production well, and the high-temperature gas generated during the combustion process further promotes the gasification reaction inside the coal seam. 
     
     
         5 . The in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane according to  claim 1 , wherein in step 4, an exhaust channel of the gasifier in the first section of coal is used as an intake channel of the gasifier in the second section of coal, and a new constructed coal gasification production well in the second section of coal is used as an exhaust channel of the gasifier in the second section of coal. 
     
     
         6 . An in-situ large-area drilling and furnace construction method for coal gasification and co-mining of kerosene and/or coalbed methane, applied to multiple coal seams, comprising the following steps:
 step 1, drilling an injection well on ground to a target coal seam, then constructing a horizontal well in the target coal seam, and dividing the target coal seam into a plurality of sections of coal, with a certain spacing between adjacent sections of coal;   step 2, constructing a first horizontal well in a first section of the coal, wherein the first horizontal well serves as both a fracturing-CO 2  injection well and a water pressure well; constructing second horizontal wells on both sides of the first horizontal well, wherein the second horizontal wells serve as both oil transportation wells and a coalbed methane transportation wells; for an upperoil-bearing coal seam in the first section of coal, injecting high-pressure liquid through the first horizontal well to perform hydraulic fracturing, followed by injecting carbon dioxide for oil displacement, and transporting the obtained kerosene to surface oil tanks through the oil transportation wells; for an upper coal seam containing coalbed methane in the first section of coal, arranging a plurality of ventilation boreholes firstly in the first section of coal for extracting the coalbed methane, wherein the overall structure of the plurality of the ventilation boreholes is honeycomb shaped, the first horizontal well is used as a water pressure well, and the water pressure well is used to maintain the stability of the plurality of the ventilation boreholes; when water pressure is lower than pressure of the coalbed methane, the second horizontal wells are used as the coalbed methane transportation wells, and the coalbed methane is slowly released and collected through the coalbed methane transportation wells;   step 3, for lower coal seams that have been drained of oil or coalbed methane, transforming the horizontal wells on both sides of the first section of coal into coal gasification production wells, and constructing ventilation boreholes in the coal gasification production wells; by arranging the ventilation boreholes, the first section of coal forms a “honeycomb briquette like” structure to construct a gasifier; injecting gasification agent on one side of the coal gasification production wells, igniting for complete combustion and gasification, and the generated gas is transported to surface facilities through the other side of the coal gasification production wells;   step 4, after the combustion of lower coal seams of the first section of coal is completed, constructing the coal gasification production well for a next section of coal, then constructing ventilation boreholes to construct another gasifier to achieve continuous combustion and gasification of the coal seam;   step 5, after the oil-bearing coal seam in the second section of coal is performed oil displacement, repeating step 3 and step 4 to carry out the gasification of the coal seam.