US20160251950A1 - Underground gasification ignition method - Google Patents
Underground gasification ignition method Download PDFInfo
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- US20160251950A1 US20160251950A1 US15/032,661 US201415032661A US2016251950A1 US 20160251950 A1 US20160251950 A1 US 20160251950A1 US 201415032661 A US201415032661 A US 201415032661A US 2016251950 A1 US2016251950 A1 US 2016251950A1
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- 238000002309 gasification Methods 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 73
- 238000005553 drilling Methods 0.000 claims abstract description 99
- 239000003245 coal Substances 0.000 claims abstract description 43
- 239000007789 gas Substances 0.000 claims description 71
- 238000012423 maintenance Methods 0.000 claims description 15
- 230000000149 penetrating effect Effects 0.000 claims description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000002802 bituminous coal Substances 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 239000003077 lignite Substances 0.000 claims description 7
- 230000035515 penetration Effects 0.000 description 15
- 230000009286 beneficial effect Effects 0.000 description 5
- 239000003034 coal gas Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000000571 coke Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 239000004449 solid propellant Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005422 blasting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000005325 percolation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/295—Gasification of minerals, e.g. for producing mixtures of combustible gases
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/243—Combustion in situ
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
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- E21C43/00—
Definitions
- the channel of the directional drilling is an unsupported channel or a supported channel with sieve-tube.
- a method of underground gasification ignition comprising the following steps:
Abstract
An underground gasification ignition method comprises the following steps: making a directional drilling and a vertical well to construct an underground gasification furnace; using a cold fracturing method to pre-penetrate a coal seam; and igniting in the vertical well at an end of the directional drilling.
Description
- The present invention relates to a method of underground gasification ignition, applicable in fields such as underground coal gasification.
- The underground coal gasification is a process in which the underground coal is transferred in situ into combustible gas through thermal chemistry reaction. As a clean coal technology, underground coal gasification has obvious technological advantages in mining low grade coal seam, deep coal seam, thin coal seam and three under-coals (under waters, buildings or roads), thus being particularly suitable for the energy resource situation of amplitude of coal, short of oil and deficiency of gas. The technology of underground coal gasification has the economical and social benefits of small investment, short construction period and friendly circumstance, thus it has received highly attention in the international coal industry. In recent few years, as the energy situation becomes more and more stressful, science research colleges and institutes and related enterprises have made much effort on development of underground coal gasification technology, thus it has a fast development.
- In the application of underground coal gasification technology, ignition in the gasification furnace and penetration and processing of a channel are very important procedures. In the current underground gasification process, channel processing often employs air firepower percolation method, hydraulic fracturing method and electrical penetration method, of which the penetration speeds are comparatively slow.
- The existing underground gasification ignition method mainly followed a certain order. Firstly, a vertical well should be created, and then light a fire in the vertical well. After the fire zone was established in the vertical well bottom, the directional drillings were created. Because of the established fire zone, the directional drillings were actually processed in hot state. And after that, the channel was penetrated through the fire. Since that only vertical wells were processed when igniting, so the penetration speeds between the vertical wells were slow, and more time should be used to penetrate the wells. It means that flame moving slowly would result in low efficiency.
- Against the shortcomings of the prior art, the present invention aims to provide a method of underground coal gasification ignition, in particular relates to a method of underground gasification ignition comprising the following steps:
- (1) creating a directional drilling and vertical well(s) to construct an underground gasification furnace;
- (2) pre-penetrating the coal seam in the method of cold fracturing;
- (3) igniting in the vertical well at the end of the directional drilling. In the present invention, firstly the directional drilling and vertical well are created to construct an underground gasification furnace. Then the coal seam in the gasification furnace is fractured in cold the status and ignition is made in the vertical well at the end of the directional drilling. This method has the advantages of high ignition efficiency and fast penetrating speed.
- The following is described as the preferred technical solutions of the present invention, but not as the restriction for the technical solutions provided by the present invention. With the following technical solutions, the technical goal and beneficial effect of the present invention can be achieved in a better way.
- Optionally, on the basis of the technical solutions provided by the present invention, step (4) is conducted after the step (3), wherein after ignition source is formed, gas inlet hole and gas outlet hole are switched and the gasification channel is processed with firepower.
- Optionally, on the basis of the technical solutions provided by the present invention, in the step (4) gas inlet hole and gas outlet hole are switched to the status that gas is discharged through the ignition vertical well.
- Optionally, on the basis of the technical solutions provided by the present invention, in the step (4) the ignition source is considered to be formed when the coal-burning volume is ≧0.5 cubic meters.
- Preferably, on the basis of the technical solutions provided by the present invention, the number of the vertical well is 1.
- In the step (3), ignition is made in the vertical well at the end of the directional drilling and gas is discharged through the directional drilling. Preferably, on the basis of the technical solutions provided by the present invention, the number of the vertical wells is at least 2.
- In the step (3), ignition is made in one of the vertical wells at the end of the directional drilling, and gas is discharged through at least one of the other vertical wells and pressure maintenance is made for the directional drilling at the same time. Preferably, on the basis of the technical solutions provided by the present invention, the pressure maintenance in step (3) is maintaining pressure within 0.3-1.0 MPa.
- Preferably, on the basis of the technical solutions provided by the present invention, the coal is brown coal and the vertical distance between the vertical well and the directional drilling channel is 2-10 meters.
- Preferably, on the basis of the technical solutions provided by the present invention, the coal is bituminous coal and the vertical distance from the vertical well to the directional drilling channel is 1-5 meters.
- Preferably, on the basis of the technical solutions provided by the present invention, the gasification agent used for ignition is oxygen-containing gas and its oxygen concentration is ≧21%.
- Compared with the prior art, the present invention has the following beneficial effect: in the present invention, directional drilling and vertical well are firstly created to construct an underground gasification furnace; the coal seam is pre-penetrated in the manner of cold fracturing; ignition is made in the vertical well at the end of the directional drilling. The method of the present invention has advantages of high ignition efficiency and fast penetrating speed.
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FIG. 1 shows the process flow chart of the ignition method of Example 1. -
FIG. 2 shows the side view of the ignition process of Example 1. -
FIG. 3 shows the vertical view of the ignition and penetration process of Example 1. -
FIG. 4 shows the side view of the ignition process of Example 2. -
FIG. 5 shows the vertical view of the ignition and penetration process of Example 2. -
FIG. 6 shows the process flow chart of the ignition method of Example 3. -
FIG. 7 shows the side view of the ignition process of Example 3. -
FIG. 8 shows the vertical view of the ignition and penetration process of Example 3. -
FIG. 9 shows the process flow chart of the ignition method of Example 4. -
FIG. 10 shows the side view of the ignition process of Example 4. -
FIG. 11 shows the vertical view of the ignition and penetration process of Example 4. - For better illustrating the present invention and understanding of the technical solutions of the present invention, the typical but non-limiting embodiments of the present invention are described in the following:
- In a typical embodiment of the present invention, an underground gasification ignition method comprises the following steps:
- (1) creating a directional drilling and vertical well(s) to construct an underground gasification furnace;
- (2) pre-penetrating the coal seam in the manner of cold fracturing;
- (3) igniting in the vertical well at the end of the directional drilling. In the present invention, firstly directional drilling and vertical well are created to construct the underground gasification furnace; the coal seam is pre-penetrated in the manner of cold fracturing; ignition is made in the vertical well at the end of the directional drilling. In the present invention, firstly a gasification furnace composed of directional drilling and vertical well is constructed and ignition in vertical well is made after cold fracturing. When first creating directional drilling then conducting the fracturing, the fracturing efficiency is improved because a horizontal channel has been formed and penetration is speeded up after the ignition of the fractured channel; the ignition efficiency is improved because the fire work face movement is faster; and it is beneficial to the future operation of the gasification furnaces composed of directional drillings, because the current industrial gasification furnaces are usually composed of directional drillings.
- Moreover, the present invention also overcomes the disadvantage of the prior art than burning area is firstly constructed in the bottom of the vertical well and then the directional drilling is processed at high temperature, thus the holing through process is greatly affected by the processing of directional drilling.
- According to the present invention, the step (4) is conducted after the step (3), wherein after the ignition source is formed, gas inlet hole and gas outlet hole are switched and the gasification channel is processed with firepower. According to the present invention, in the step (4), the gas inlet hole and gas outlet hole are switched to the status that gas is discharged through the vertical well.
- According to the present invention, in the step (4), the ignition source is considered to be formed when the coal-burning volume is cubic meter.
- The step (4) of the present invention further comprises a reliable control method on the basis of previous steps, wherein whether ignition source has been formed is determined by coal-burning volume at the coal gas outlet hole, thus gas inlet hole can be switched in time, preventing from the collapse of top plate of the coal seam induced by partial channel being too wide.
- According to the present invention, when the number of the vertical well is 1, in the step (3) ignition is made in the vertical well and gas is discharged through directional drilling. When the coal-burning volume is ≧0.5 cubic meter, ignition source is considered to be formed, then the gas outlet hole and gas inlet hole are switched to the status that gas is introduced through the directional drilling and discharged through the vertical well.
- According to the present invention, when the number of the vertical wells is at least 2, in the step (3) ignition is made in one of the vertical wells at the end of the directional drilling, gas is discharged in at least one of the other vertical wells and pressure maintenance is made for the directional drilling at the same time.
- When the number of the vertical wells is 2, in the step (3) ignition is made in one of the vertical wells and gas is discharged in the other vertical well. When the coal-burning volume is ≧0.5 cubic meter, the ignition source is considered to be formed. Then the gas outlet hole and gas inlet hole are switched according to the position of the ignition hole to the status that gas is introduced through directional drilling or the previous gas outlet vertical well, and gas is discharged through the ignition vertical well, all of which aim to process the gasification channel with firepower so as to penetrate the gasification channel.
- When the number of the vertical wells is at least 3, in the step (3) firstly any one of the vertical wells is selected for ignition, and gas is discharged through at least one of the other vertical wells. When the coal-burning volume is ≧0.5 cubic meter, the ignition source is considered to be formed, then the gas outlet hole and gas inlet hole are switched according to the position of the ignition hole to the status that gas is introduced through the directional drilling, an auxiliary well or the previous gas outlet well, and gas is discharged through the ignition vertical well, all of which aim to process gasification channel with firepower so as to penetrate the gasification channel. The auxiliary wells are the vertical wells other than the ignition vertical well and the previous gas outlet well in the step (3).
- In the step (3) of the present invention, pressure maintenance is made for directional drilling in the process of vertical well ignition and penetration, in order to prevent from the occlusion induced by late use after the directional drilling is finished and also to effectively prevent from the entry of underground water.
- The number of the vertical wells is at least one, such as 1, 2, 3, 4, 5, 6, 7, etc.
- The aperture diameter of the vertical well is 200-400 mm, such as 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 360 mm or 380 mm.
- The distance from the bottom of casing tube of the vertical well to the bottom plate of the coal seam is 1-2 meters.
- The channel of the directional drilling is an unsupported channel or a supported channel with sieve-tube.
- The length of the directional drilling channel is 70-150 meters, such as 80 meters, 90 meters, 100 meters, 110 meters, 120 meters, 130 meters, or 140 meters.
- The aperture diameter of the directional drilling is 100-250 mm, such as 110 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm or 245 mm.
- In the present invention, the vertical well is not directly connected with the directional drilling. When the coal is brown coal, the vertical distance between the vertical well and the directional drilling channel is 2-10 meters, such as 3 meters, 4 meters, 5 meters, 6 meters, 7 meters, 8 meters or 9 meters. When the coal is bituminous coal, the vertical distance between the vertical well and the directional drilling channel is 1-5 meters, such as 1.5 meters, 2 meters, 2.5 meters, 3 meters, 3.5 meters, 4 meters or 4.5 meters.
- The fracturing method is any one of the methods of hydraulic fracturing, high-pressure air permeation, blasting or chemical solution breaking.
- The ignition in the vertical well is any one of electric ignition, solid fuel ignition or coke ignition.
- The gasification agent used for ignition is oxygen-containing gas and its oxygen concentration is 21%, such as 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.
- The pressure maintenance of the step (3) aims to keep pressure within 0.3-1.0 Mpa, such as 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 Mpa or 0.9 Mpa. The pressure maintenance can be realized by continuously aerating the directional drilling.
- The beneficial effects of the present invention will be further illustrated in the following referring to the specific embodiments and specific examples.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling and a vertical well to construct an underground gasification furnace, wherein the number of the vertical well is 1;
- (2′) pre-penetrating coal seam in the manner of cold fracturing;
- (3′) igniting in the vertical well at the end of the directional drilling.
- (4′) when the coal-burning volume is ≧0.5 cube meter, a ignition source being considered to be formed; then it being switched to the status that gas is introduced through the directional drilling, and gas is discharged through the vertical well and the gasification channel being processed with firepower.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling well and vertical wells to construct an underground gasification furnace, wherein the number of the vertical wells is 2;
- (2′) pre-penetrating coal seam in the manner of cold fracturing;
- (3′) igniting in one of the vertical wells at the end of the directional drilling; gas being discharged through the other vertical well; pressure maintenance being made for the directional drilling during the process of the vertical well ignition and penetration;
- (4′) when the coal-burning volume is ≧0.5 cubic meter, a ignition source being considered to be formed; then it being switched according to the position of ignition hole to the status that air is introduced through the directional drilling, and gas is discharged through the ignition vertical well and the gasification channel being processed with firepower.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling and vertical wells to construct an underground gasification furnace, wherein the number of the vertical wells is 2;
- (2′) pre-penetrating coal seam in the manner of cold fracturing;
- (3′) igniting in one of the vertical wells at the end of the directional drilling; gas being discharged through the other vertical well; pressure maintenance being made for the directional drilling during the process of vertical well ignition and penetration;
- (4′) when the coal-burning volume is ≧0.5 cube meter, a ignition source is considered to be formed; then it being switched according to the position of ignition hole to the status that gas is introduced through the previously gas outlet vertical well, and gas is discharged through the ignition vertical well, and the gasification channel being processed with firepower.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling and vertical wells to construct an underground gasification furnace, wherein the number of vertical wells is at least 3;
- (2′) pre-penetrating coal seam in the manner of cold fracturing;
- (3′) igniting in one of the vertical wells at the end of the directional drilling; gas being discharged through at least one of the other vertical wells; pressure maintenance being made for the directional drilling during the process of vertical well ignition and penetration;
- (4′) when the coal-burning volume is ≧0.5 cube meter, a ignition source is considered to be formed; then it being switched according to the position of ignition hole to the status that gas is introduced through the directional drilling, and gas is discharged through the ignition vertical well, and the gasification channel being processed with firepower.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling and vertical wells to construct an underground gasification furnace, wherein the number of the vertical wells is at least 3;
- (2′) pre-penetrating the coal seam in the manner of cold fracturing;
- (3′) igniting in one of the vertical wells at the end of the directional drilling; gas being discharged through at least one of the other vertical wells; pressure maintenance being made for the directional drilling during the process of vertical well ignition and penetration;
- (4′) when the coal-burning volume is ≧0.5 cubic meter, a ignition source is considered to be formed; then it being switched according to the position of ignition hole to the status that air is introduced through the previous gas outlet vertical well, and gas is discharged through the ignition vertical well, and the gasification channel being processed with firepower.
- A method of underground gasification ignition comprising the following steps:
- (1′) creating a directional drilling and vertical wells to construct an underground gasification furnace, wherein the number of the vertical wells is at least 3;
- (2′) pre-penetrating coal seam in the manner of cold fracturing;
- (3′) igniting in one of the vertical wells at the end of the directional drilling; gas being discharged through at least one of the other vertical wells; pressure maintenance being made for the directional drilling during the process of the vertical well ignition and penetration;
- (4′) when the coal-burning volume is ≧0.5 cubic meter, a ignition source is considered to be formed; then it being switched according to the position of ignition hole to the status that gas is introduced through the auxiliary well, and gas is discharged through the ignition vertical well, and the gasification channel being processed with firepower.
- Example 1 relates to a process, wherein one directional well and one vertical well are coordinately used for ignition in the brown coal seam. This process has the advantages of high fracturing efficiency, good dewatering effect of gasification furnace and high ignition efficiency, thereby providing superior precondition for industrial application of underground gasification furnace.
- Referring to
FIGS. 1-3 , the present example mainly comprises the following steps: - (1) an underground gasification furnace composed of one directional well and one vertical well along a line near an end of the directional drilling is constructed in the brown coal seam, wherein the coal seam is of 10 meters thick, the aperture diameter of the directional drilling is 150 mm, the channel is unsupported channel, the horizontal distance is 150 m, the aperture diameter of the vertical well is 250 mm, which is located at the side of the directional drilling line, and the bottom of the casing tube is of about 2 m away from the bottom plate of the coal seam and of 10 m away from the directional drilling channel vertically;
- (2) high pressure air permeation method is used to conduct cold fracturing for the underground gasification furnace and the channel between the directional drilling and vertical well is penetrated.
- (3) solid fuel is put down in the vertical well as the ignition well; air is used as gasification agent; gas is discharged through the directional drilling; ignition source is cultivated, wherein whether the ignition source is formed is determined by coal-burning amount at coal gas outlet hole;
- (4) when the coal-burning volume is 0.5 cubic meter, the ignition source is considered to be formed; gas outlet hole and gas inlet hole are switched to the status that air is introduced through the directional drilling, and gas is discharged through the vertical well; reverse ignition is made to penetrate the gasification channel.
- Example 2 relates to a process, wherein one directional well and one vertical well are coordinately used for ignition in the bituminous coal seam. This process has the advantages of high fracturing efficiency, good dewatering effect of gasification furnace and high ignition efficiency, thereby providing superior precondition for industrial application of underground gasification furnace.
- Referring to
FIGS. 4-5 , the present example mainly comprises the following steps: - (1) an underground gasification furnace composed of one directional well and one vertical well along a line near an end of the directional drilling is built up in the bituminous coal seam, wherein the coal seam is of 10 meters thick, the aperture diameter of the directional drilling is 150 mm, the channel is unsupported channel, the horizontal distance is 120 m, the aperture diameter of the vertical well is 300 mm, which is located at the side of the directional drilling line, and the bottom of the casing tube is about 2 m away from the bottom plate of the coal seam and of 5 m away from the directional drilling channel vertically;
- (2) chemical solution breaking method is used to conduct cold fracturing for the underground gasification furnace and the channel between the directional drilling and vertical well is penetrated;
- (3) coke is put down in the vertical well as the ignition well; air containing 35% oxygen is used as gasification agent; gas is discharged through the directional drilling; ignition source is cultivated, wherein whether the ignition source is formed is determined by the coal-burning amount at the coal gas outlet hole;
- (4) when the coal-burning volume is ≧0.5 cubic meter, the ignition source is considered to be formed; gas outlet hole and air inlet hole are switched to the status that air is introduced through the directional drilling, and gas is discharged through the vertical well; reverse ignition is made to penetrated the gasification channel.
- Example 3 relates to a process, wherein one directional well and three vertical wells are coordinately used for ignition in the brown coal seam. This process has the advantages of high fracturing efficiency, good dewatering effect of gasification furnace and high ignition efficiency, thereby providing superior precondition for the sequential operation of gasification furnace composed of directional drilling.
- Referring to
FIGS. 6-8 , the present example mainly comprises the following steps: - (1) an underground gasification furnace composed of one directional well and 1#, 2# and 3# vertical wells along a line near an end of the directional drilling is constructed in the brown coal seam, wherein the coal seam is of 10 meters thick, the aperture diameter of the directional drilling is 150 mm, the channel is unsupported channel, the horizontal distance is 150 m, the vertical wells is located at the two sides of the directional drilling line, the bottom of casing tube is about 2 m away from the bottom plate of the coal seam, 1#, 2# and 3# wells have aperture diameters of 350 mm, 350 mm and 200 mm, respectively, and are 8 m, 10 m and 10 m, respectively, away from the directional drilling channel vertically and the 1# well is 30 m and 10 m, respectively, away from the 2# and 3# wells horizontally;
- (2) high pressure air permeation method is used to conduct cold fracturing for the underground gasification furnace and the channel between the directional drilling and vertical well is penetrated;
- (3) air is used as gasification agent and is continuously introduced in the directional drilling for pressure maintenance; ignition is made in 1# vertical well; gas is discharged through 2# vertical well; ignition source is cultivated, wherein the ignition source is considered to be formed when the coal-burning volume at the coal gas outlet hole reaches 1 cubic meter;
- (4) after the ignition source is formed, air introduction in 1# ignition well is stopped and it is switched to the status that air is introduced in 3# vertical well and gas is discharged through 1# vertical well.
- Example 4 relates to a process, wherein one directional well and 2 vertical wells are coordinately used for ignition in the bituminous coal seam. This process has the advantages of high fracturing efficiency, good dewatering effect of underground gasification furnace, high ignition efficiency, and rapid holing through for the vertical well, thereby being beneficial to the sequential operation of gasification furnace composed of directional drilling.
- Referring to
FIGS. 9-11 , the present example mainly comprises of the following steps: - (1) an underground gasification furnace composed of one directional well and 1# and 2# vertical wells along a line near an end of the directional drilling is constructed in the bituminous coal seam, wherein the coal seam is of 10 meters thick, the aperture diameter of the directional drilling is 150 mm, the channel is disposed with sieve-tube support, the horizontal distance is 120 m, the vertical wells is located at the two sides of the directional drilling line, the bottom of casing tube is about 2 m away from the bottom plate of the coal seam, both 1# and 2#wells have aperture diameters of 250 mm and are 5 m away from the directional drilling channel vertically, and the distance between the two wells is 25 meters;
- (2) cold fracturing is made for the underground gasification furnace and the channel between the directional drilling and vertical well is penetrated;
- (3) air containing 30% oxygen is used as gasification agent and is continuously introduced into the directional drilling for pressure maintenance; coke ignition is made in 2# vertical well; gas is discharged through 1# vertical well; ignition source is cultivated, wherein whether the ignition source is formed is determined by the coal-burning volume at the coal gas outlet hole;
- (4) when the coal-burning volume is ≧0.5 cubic meter, the ignition source is considered to be formed; after the ignition source is formed, air introduction in 2# ignition well is stopped and air is introduced in the directional drilling instead; reverse ignition is made; air is continuously introduced in the directional drilling; gas outlet well is switched to 2# well to prolong the gasification channel.
- The applicant states that the present invention employs the above embodiments to describe the detailed methods of the present invention, but the present invention is not limited to the detailed above methods, i.e. it does not mean that the present invention must rely on the above detailed method to be implemented. Persons skilled in the art should understand any improvement of the present invention, the equivalent replacement to the raw materials of the present invention product, the addition of auxiliary ingredients and the selection of specific mode all fall into the protection scope and disclosure scope of the present invention.
Claims (10)
1. A method of underground gasification ignition, comprising the following steps:
(1) creating a directional drilling and vertical well(s) to construct an underground gasification furnace;
(2) pre-penetrating the coal seam in the manner of cold fracturing; and
(3) igniting in the vertical well at the end of the directional drilling.
2. The method according to claim 1 , further comprising step (4) following step (3), wherein after an ignition source is formed, a gas inlet hole and a gas outlet hole are switched and a gasification channel is processed with firepower.
3. The method according to claim 2 , wherein the gas inlet hole and the gas outlet hole are switched to the status that gas is discharged through the ignition vertical well.
4. The method according to claim 2 , wherein the ignition source is considered to be formed when coal-burning volume is ≧0.5 cubic meter.
5. The method according to claim 1 , wherein the number of the vertical well is 1; and wherein in step (3) ignition is made in the vertical well at the end of the directional drilling and gas is discharged through the directional drilling.
6. The method according to claim 1 , wherein the number of the vertical wells is at least 2; and wherein in step (3), ignition is made in one of the vertical wells at the end of the directional drilling, gas is discharged through at least one of the other vertical wells and pressure maintenance is made in the directional drilling at the same time.
7. The method according to claim 6 , wherein the pressure maintenance is maintaining pressure within 0.3-1.0 MPa.
8. The method according to claim 1 , wherein the coal is brown coal and the vertical distance between the vertical well and the directional drilling channel is 2-10 meters.
9. The method according to claim 1 , wherein the coal is bituminous coal and the vertical distance between the vertical well and the directional drilling channel is 1-5 meters.
10. The method according to claim 1 , wherein oxygen-containing gas is used as a gasification agent for ignition and its oxygen concentration is ≧21%.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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CN201310717057.9 | 2013-12-23 | ||
CN201310717057.9A CN103726818A (en) | 2013-12-23 | 2013-12-23 | Underground gasification ignition method |
PCT/CN2014/074202 WO2015096290A1 (en) | 2013-12-23 | 2014-03-27 | Underground gasification ignition method |
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US20160251950A1 true US20160251950A1 (en) | 2016-09-01 |
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Application Number | Title | Priority Date | Filing Date |
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US15/032,661 Abandoned US20160251950A1 (en) | 2013-12-23 | 2014-03-27 | Underground gasification ignition method |
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US (1) | US20160251950A1 (en) |
EP (1) | EP3088660A1 (en) |
CN (1) | CN103726818A (en) |
WO (1) | WO2015096290A1 (en) |
ZA (1) | ZA201602967B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2018080733A1 (en) * | 2016-10-31 | 2018-05-03 | Baker Hughes, A Ge Company, Llc | System and method for downhole ignition detection |
CN112127866A (en) * | 2019-06-25 | 2020-12-25 | 中国石油天然气股份有限公司 | Process for developing deep coal bed by using underground coal gasification technology |
Families Citing this family (5)
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CN107083948A (en) * | 2017-06-16 | 2017-08-22 | 新疆国利衡清洁能源科技有限公司 | A kind of coal underground gasifying furnace furnace body structure and construction method |
CN107227947A (en) * | 2017-07-24 | 2017-10-03 | 新疆国利衡清洁能源科技有限公司 | A kind of underground gasification furnace and its construction method and coal underground gasification method |
CN111963137B (en) * | 2019-05-20 | 2022-11-04 | 中国石油天然气股份有限公司 | Underground gasification method for huge thick coal seam |
CN112177586B (en) * | 2020-09-26 | 2022-09-16 | 陕西省煤田地质集团有限公司 | Polyhalite in-situ roasting exploitation method |
CN113914847A (en) * | 2021-10-22 | 2022-01-11 | 西南石油大学 | Method for improving development of underground coal gasification air cavity by applying fracturing technology |
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CN112127866A (en) * | 2019-06-25 | 2020-12-25 | 中国石油天然气股份有限公司 | Process for developing deep coal bed by using underground coal gasification technology |
Also Published As
Publication number | Publication date |
---|---|
EP3088660A1 (en) | 2016-11-02 |
CN103726818A (en) | 2014-04-16 |
WO2015096290A1 (en) | 2015-07-02 |
ZA201602967B (en) | 2017-07-26 |
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Legal Events
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Owner name: ENN COAL GASIFICATION MINING CO., LTD., CHINA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHEN, FENG;LIU, HONGTAO;REEL/FRAME:038401/0109 Effective date: 20160226 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |