Method of underground gasification |
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IPC classes for russian patent Method of underground gasification (RU 2521255):
 Method of extraction of high-molecular raw material of oil and gas condensate field / 2519310
Method involves fire action on a field through system of surface wells by ignition of raw hydrocarbons at their opened bottomhole, injection of high-pressure air into deposit, creation of raw hydrocarbon combustion zones in it and active heating of the high-molecular raw material deposit, and consequently, reduction of its viscosity and extraction availability through production wells. According to the invention, a deposit of high-molecular raw material is drilled with vertical wells on the surface, which central one is equipped for ignition of raw hydrocarbon and offset ones removed from the central well to the preselected distance are equipped for high-pressure air injection. At that, on account of reverse-flow forward combustion from the central production well to offsite injection wells, artificial reservoirs of increased drainage capacity are formed. Composition of mixture extracted from the central production well is monitored, and in case if free oxygen found in it is in the amount of over 1%, a source of its occurrence is detected by successive disconnection of the offside vertical injection wells. Consumption of injected air in well - a source of oxygen penetration - is reduced.
 Method for disposal of carbon dioxide (co2) from underground-coal-gasification-derived gas (ucg-derived gas) / 2513947
Invention relates to mining and can be used for underground coal gasification. The method lies in division of CO2 received in the surface chemical complex into two flows: the first flow is injected into blast injection holes of the operating underground gas generator and endothermic chemical reaction CO2+C=2CO-q is initiated in gasification zones thus enriching UCG-derived gas with combustible CO component; the second flow of CO2 is injected into depleted underground gas generator. At that quantity of CO2 injected to the operating underground gas generator is determined depending on temperature level in gasification oxidising zone and composition of the gas extracted from the neighbouring well. Bottom-ash mass of the depleted underground gas generator is saturated with lime hydrate aqueous solution [Ca(OH)2], to that end it is injected into wells of the depleted underground gas generator until concentration of this solution is stabilised which is proven by periodical solution sampling and chemical analysis of that. When concentration of lime hydrate is stabilised in analysed samples the second CO2 flow is injected into wells of the depleted gas generator for the purpose of its chemical absorption. Injection of CO2 is stopped to the depleted gas generator when its concentration in periodic samples increases up to 90%.
 Gas emission control method at development of coal bed prone to spontaneous ignition / 2512049
Method refers to the field of mining industry, to coal mining industry in particular, and may be used during development of coal beds prone to spontaneous ignition. The method used during development of coal bed prone to spontaneous ignition includes preparation of extraction section by double workings, ventilation of wide section workings due to mine ventilating pressure drop and coalmine methane extraction from emission source. Methane is extracted first through drilled at superimposed beds methane drainage boreholes with possibility of air inleakage exclusion from bottom-hole region of active stope. Then after displacement of developed bed main roof mine rocks, methane is removed through the rest part of borehole length in modes excluding air inleakage from bottom-hole space of long face. Methane, evolving hard from developed bed zones released from overburden pressure near long face bottom-hole, is offtaken to degassing vacuum network of extraction section through formation wells drilled oriented on working face with methane concentration fit for disposal.
 Procedure for underground gasification of coal / 2490445
Method involves drilling of an air injection hole and gas removal hole in a coal bed, including setting of pipe string, connection of holes in the bed by hydraulic fracturing with formation of a channel. Ferric oxide is loaded into a channel; at that quantity of ferric oxide is equal to 0.25-0.35 of the mass of gasifiable coal bed. Coal ignition is made by coal bed heating up to 300-500°C. Superheated steam of the same temperature is supplied to the channel and combustible gas with hydrogen content of 17-34% and calorific capacity of 6.5-15.2 MJ/m3 depending on the process temperature is removed through the gas removal hole.
 Method for underground gasification / 2477788
Method includes well drilling from ground surface into treated interval of formation, electrodes allocation in wells, voltage supply to electrodes, electric current supply and formation heating. In order to provide maximum output of heat generation in the formation the current frequency is chosen depending upon maximum of angle tangent of dielectric losses of the rock and electric current of chosen frequency is fed through the formation. Heating is done due to dielectric and resistant losses in the formation. In the course of formation heating there performed is a gradual changing of electric current frequency according to the change of maximum of angle tangent of dielectric losses of the rock. Note that wells for electrodes location are drilled by grid-intersection coordinates in points of square network, and gas draw-off wells in the centre of network squares.
 Method to produce hydrogen during underground coal gasification / 2443857
According to the method, air or technical oxygen are supplied as blowing to a hot coal surface of an underground gas generator. Produced gas is discharged via gas-discharge wells ending with coal shafts without pipe casing. Technological process parameters are controlled via gas-discharge wells. The reaction of steam conversion of carbon monoxide is initiated in the reaction channel of the underground gas generator by injection of water vapour or surface water into reaction zones of coal shafts of gas-discharge wells via sections of auxiliary wells having hydraulic connection with the specified reaction zones and perforated in preset areas along the length of rock shafts, and such auxiliary wells are drilled along every gas-discharge well and cased with pipes along the entire length. As the coal bed is mined by gasification, and reaction zones of coal shafts of the gas-discharge wells are displaced, the point of water vapour or surface water supply in rock shafts of auxiliary wells is moved following displacement of reaction zones of coal shafts of the gas-discharge wells. Also the reaction of steam conversion of carbon monoxide is initiated in the ground chemical complex. Gas composition is monitored. Water vapour or surface water are injected in amount that provides for reduction and stabilisation of carbon monoxide concentration in discharged gas up to 3-5 percent. Steam conversion of carbon monoxide in the ground chemical complex is carried out before its stable minimum is demonstrated, by selection of appropriate optimal types of catalyst and thermobaric conditions, and after completion of steam conversion of carbon monoxide in the ground chemical complex the carbon dioxide is caught and recycled, and remaining hydrogen is transferred to a consumer.
 Underground coal gasification technique / 2441980
FIELD: underground coal gasification. SUBSTANCE: invention belongs to the mining engineering and may be used for the underground coal gasification (UCG). The technique lies in drilling of development wells of the underground gas generator, implementation of a technological UCG process and minimization of the environmental impact on the massif mass. The direction of the drilled well is oriented at its lower bench, while vertical water wells and initial spots of directionally drilled well are located beyond the active displacement zone. The distance between the blasting and pressure relief well shall be greater than the roof fragmentation step. Ignition of the coal formation is carried out in the vertical well, what is followed by a monitoring of its connectivity with the cross sectional horizontal and boundary pressure relief wells. The monitoring of coal formation outgasing is carried out between every pair of blasting and pressure relief well; such outgasing is equaled along the underground gas generator. Gasification plot is preliminary dried to the level of 20-25 m over the inflammation horizon and keep up pressure in the underground gas generator, which should be lower, than the underground water pressure. Upon the cessation of the underground gas generator exploitation the blasting wells are injected with nitrogen for a final fire face extinguishment. EFFECT: optimum implementation of UCG technique within the whole cycle. 15 cl, 2 dwg  Method to prepare power gas of underground gasification of stone and brown coals / 2439313
Method includes primary cooling of gas in a well of an underground gasification rig using supply of sprayed water into a wall or a recuperative boiler, in which cooled gas and cooling water are separated with a wall, forced gas suction from the well, its cleaning and burning to produce heat and power energy. Primary gas cooling is carried out to the temperature of not less than 600°C. At the same time gas cleaning from dust is carried out by dry method at one, two or three stages, combining a cyclone device, a cyclone device of battery type, an electric filter or a cassette filter from gauze nets. Gas supply for burning is carried out at the temperature that is higher than temperature of stone coal resin condensation, i.e. not below 400°C.
 Utilisation method of worn-out automobile tyres at development of coal beds by underground gasification method / 2435954
Method involves preparation of gas generator for gasification by drilling a network of wells: vertical ones for blast air supply, formation ones for gas removal; in addition, between blast air and gas-removing wells there drilled are formation wells through which wastes are supplied to combustion source, combustion face is moved along the rise and spread of coal bed by supplying the blast air to blast air wells and gas removal through gas-removing wells. At that, as utilisation wastes there used is rubber of pre-crushed automobile tyres, which is supplied to combustion source when necessary through the dosing devices installed in formation wells.
 Procedure for underground gasification of coal / 2424429
Procedure for underground gasification of coal includes arrangement of chambers along bed of coal. The chambers are connected with surface at their mouths and are interconnected at their ends. Further, the procedure consists in sealing mouths, in installation of devices for blowing and gas withdrawal and in successive burning coal massifs. Also, one pair of chambers is drilled differently directed at angle one to another from one mouth and are connected with the next pair of chambers at their end. Mouths of chambers and beat of bed on surface are isolated with a continuous sealing wall.
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FIELD: mining. SUBSTANCE: proposed method comprises well drilling from surface into processed interval in underground sea, placing the electrodes in the wells, application of voltage to said electrodes and heating of the seam of Joule heat. Voltage sufficient for producing of partial discharges and treeing is applied to electrodes to make the channel of electric-heat disruption of the seam, its formation being used for conclusion about decreased in electrode dap resistance. Then, current is passed via said channel of electric-heat disruption of the seam. EFFECT: lower labour input and costs. 1 dwg
The invention relates to mining, in particular to a method of underground gasification of solid fossil fuels, and can be used to obtain a gaseous energy carrier (fuel gas) from coal or shale in-situ. There is a method of underground gasification, including the drilling of wells, their linkage, ignition, supply air and exhaust productive gas [RF Patent №2385412, IPC E21B43/295, publ. 27.03.2010]. The disadvantage of this method is the low energy (calories) produced commercial gas due to the presence of a large number of ballast gas resulting from combustion of organic matter in the underground chamber of the gas generator. A method of processing a subterranean formation that contains solid organic matter, including the provision of at least one well, passing the treated interval in the underground layer, creating at least one gap from at least one well, which crosses at least one borehole, placing electrically conductive material in the gap, making contact between two electrodes with conductive material, the application of voltage to the two electrodes for passing an electric current through the gap so that the electric current passes through at least part of electr the conductive material and sufficient heat producing electrical resistivity in part of electrically conductive material for the pyrolysis, at least part of the solid organic matter extractable hydrocarbons [RF Patent №2349745, IPC E21B43/24, publ. 20.03.2009]. The method chosen for the prototype. The disadvantage of the prototype is the complexity of the method associated with the presence of additional technological operations, the possible toxicity of electrically conductive material. The objective of the invention is to create an effective, environmentally sound method of underground gasification. The technical result is achieved by the use of the invention is to reduce the complexity of the way of gasification, the reduction in economic costs in the preparation of gasification by creating a channel electrothermal breakdown in the reservoir. This technical result is achieved in that in the method of underground gasification, including, as a prototype, the drilling of boreholes from the ground surface to the treated interval in the underground reservoir, accommodation in wells electrodes, the application of voltage to the electrodes, passing electric current and heating of the reservoir, unlike the prototype, the electrodes apply a voltage sufficient for the occurrence of partial discharges and trying to education channel electrothermal breakdown in the reservoir, the formation of which is judged by the reduction of the resistance of the interelectrode space, then pass the current through the channel of the electrothermal breakdown in the reservoir and carry out the heating of the reservoir due dzhoulevo heat. The invention is illustrated by figure 1, which shows a functional diagram of the method of underground gasification. Method of underground gasification includes the drilling of two wells 1 with the ground surface, passing the treated interval from an underground formation 2 solid fossil fuel and accommodation within them the electrodes 3 connected by cables with the ground power source 4 (figure 1). Gasification is carried out by heating the layer to a temperature of the gas solid fuel (300-500°C). Heat rocks are produced by passing current through the channel of the electrothermal breakdown due dzhoulevo heat. The electrical resistance of solid fuels is large (108÷1012Ohm·cm), so Joul warmth educed in the breed when technically possible values of voltage will be small. The Annex to the interelectrode gap layer high AC voltage causes partial discharges, which form conductive areas at the site of action of the discharge in the total rock volume of the solid fuel. The following discharge extends conductive area. Growing up in the bit structure called a dendrite, is a tree-like shape and extends from the electrodes toward the other electrode polarity. This process, called trainham, education continues to SLE the knowledge of the channel between the electrodes. Applied to the electrodes, the voltage at this point should be sufficient for the formation of partial discharges. This voltage depends on the distance between the electrodes and the type of breed. The voltage determined experimentally on samples retrieved to the surface. The presence of partial discharges in this set visually, and the formation of a conducting channel determined to reduce the interelectrode resistance. The voltage needs to be somewhere between 1-10 kV/m, you Must use an alternating voltage can be used voltage of industrial frequency. When the dendrites growing up with a bipolar electrode, closed, forming a through a conductive channel between the electrodes, the linear resistance of the interelectrode gap becomes low (10-100 Ohm/cm). To determine the moment of formation of the channel control voltage on the electrodes and the current between them. It is possible to heat dzhoulevo heat formed in the conductive channel. At this stage, the electrodes connect high-current DC or AC voltage. Next, perform heating by dzhoulevo heat in the conductive channel. The voltage source in this mode can be 10-100 V/m, and the current is limited by the power source and may be 10-100 A. Example 1 About the Eden laboratory test method in the experimental chamber on the sample of oil shale with the distance between the electrodes 50, see Pre-measured ohmic resistance of the interelectrode distance was ~250 ohms. At the initial stage to the electrodes was applied sinusoidal voltage of frequency 50 Hz and amplitude of 5 kV. This voltage is enough to cause partial discharges, which established visually. From the source of consumed power ~300 watts. This regime continued for 30 minutes after this time formed through the conducting channel. Ohmic resistance of the interelectrode distance was ~800 Ohms. Then through the interelectrode gap was passed current frequency of 50 Hz from the regulated voltage source, and heating was carried out at the expense of dzhoulevo heat formed in the low-resistance channel. The first voltage amounted to hundreds of volts as heat channel its resistance decreased to ~10 Ohms, the voltage was reduced to 100 to maintain the power of ~1 kW. Example 2 Conducted laboratory testing of the method in the experimental chamber on the sample of brown coal with the distance between the electrodes 45 see Pre-measured ohmic resistance of the interelectrode distance was ~150 ohms. At the initial stage to the electrodes was applied sinusoidal voltage with frequency of 50 Hz and an amplitude of 8 kV. This voltage is enough to cause partial discharges,which established visually. From the source of the consumed power is ~600 watts. This regime continued for 15 minutes after this time formed through the conducting channel. Ohmic resistance of the interelectrode distance was to be ~300 Ohms. Then through the interelectrode gap was passed current frequency of 50 Hz from the regulated voltage source, and heating was carried out at the expense of dzhoulevo heat formed in the low-resistance channel. The first voltage amounted to hundreds of volts as heat channel its resistance decreased to ~3-5 Ohms, the voltage was reduced to 60 to maintain the power of ~1 kW. Thus, the inventive method reduces the amount of preparatory work, to exclude hydraulic fracturing and the use of toxic electrically conductive material and to increase the efficiency of the process. Method of underground gasification, including the drilling of boreholes from the ground surface to the treated interval in the underground reservoir, accommodation in wells electrodes, the application of voltage to the electrodes, passing electric current and heating of the reservoir due dzhoulevo heat, characterized in that the electrodes apply a voltage sufficient for the occurrence of partial discharges and trying to education channel electrothermal breakdown in the reservoir, the formation of which is judged by the reduction of the structure resistance of the interelectrode space, then pass the current through the channel of the electrothermal breakdown in the reservoir.
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