WO2009157811A1

WO2009157811A1 - Coal gasification method (variants) and a subsurface water purification method

Info

Publication number: WO2009157811A1
Application number: PCT/RU2009/000315
Authority: WO
Inventors: Александр Мирославович КАРАСЕВИЧ; Ефим Вульфович КРЕЙНИН; Елена Васильевна ДВОРНИКОВА; Станислав Геннадьевич СТРЕЛЬЦОВ; Белла Юрьевна СУШЕНЦОВА; Алексей Юрьевич ЗОРЯ
Original assignee: Открытое Акционерное Общество "Газпром Промгаз"
Priority date: 2008-06-26
Filing date: 2009-06-24
Publication date: 2009-12-30

Abstract

The invention relates to subsurface coal gasification. The aim of the invention is to prevent subsurface water from being contaminated. A range of wells is drilled on a gasification field. The blasting and gas exhaust wells are connected into a single underground gas producer by means of a transversal slant and horizontal well and vertical wells connected thereto. The pressure in the underground gas producer, a subsurface water hydrostatic level and the concentration of chemical contaminants are monitored during gasification. The hydraulic controls of the blasting and gas exhaust wells are adjusted. The subsurface coal gasification process is carried out successively in two stages, i.e a pressure stage carried out at a high pressure in the underground gas producer and a pressure and suction stage carried out at a minimum pressure in the underground gas producer. At the first stage of subsurface coal gasification, the subsurface water hydrostatic level is increased by disconnecting water-removing and drainage wells, and at the second stage of subsurface coal gasification, the performance of the water-removing wells and smoke exhausters on the gas exhaust wells is increased. The extracted subsurface water is purified in a surface system by removing the chemical contaminants therefrom. The second variant of the coal gasification method differs in that the wells are cased along the entire length thereof, including the rock and coal parts. The blasting and gas exhaust wells are interconnected by fire treatment which is associated with the casing pipe melting and expanding the coal sections of the transversal slant and horizontal well and alternately of each of the gas exhaust wells starting from the well adjacent to a place where the coal stratum is ignited. The subsurface water is purified in the worked out space of the underground gas producer by biological degradation and by neutralising the chemical contaminants generated during the subsurface coal gasification process.

Description

METHOD OF COAL GASIFICATION (OPTIONS) AND METHOD FOR CLEANING UNDERGROUND WATERS

Technical field

The invention relates to the field of mining and, above all, to underground coal gasification (CCGT) at its natural occurrence site, including at great depths, with the prevention of ecological pollution of underground hydrosphere waters by products of thermal decomposition of coal (phenols, ammonium, etc.) both in the process of gasification, and after the completion of gas formation of the coal seam.

State of the art

Special hydrochemical studies conducted at the Podzemgaz Yuzhno-Abinsk station using a group of hydro-observation wells revealed the pollution of groundwater with phenols during the CCGT process [E. Kreinin. Non-traditional thermal technologies for the extraction of hard-to-recover fuels: coal, hydrocarbon raw materials. Moscow, 000 IRC Gazprom, 2004, p.177-182]. Moreover, the concentration of phenols (C ₆ H ₅ OH) exceeded the maximum permissible concentration (PDK = 0.001 mg / l) for a long time and at a distance of up to 300-400 m. Self-purification of groundwater was achieved mainly by the decomposition of phenols and their adsorption by rocks. There were no technical solutions to prevent groundwater pollution. No technological and engineering barrage measures were envisaged to reduce the migration of gasification products outside the underground gas generator.

A well-known technical solution to reduce groundwater pollution outside the underground gas generator was the implementation of CCGT at a pressure in the underground gas generator close to the pressure of the hydrostatic column of groundwater at the gasification site [RU 2090750, 1997]. In this case, the groundwater column is a natural barrier to the migration of gasification products outside the working space of the underground gas generator.

However, the disadvantage of this technical solution is the impossibility of its use in the process of draining the gasification section and, accordingly, lowering the groundwater level.

Another well-known technical solution is the injection and exhaust CCGT, in which the gas exhaust wells are equipped with smoke exhausters, as a result of which it is possible to reduce the pressure in the working space of the underground gas generator, and, consequently, leakage of gasification products from it [RU 2066748, 1996].

The disadvantage of this technical solution is the limited application. Only at shallow depths (up to 150 m) is it possible to lower the pressure in the underground gas generator, since with the length of the casing strings of the exhaust wells more than 150-200 m, the possibility of creating a vacuum in the wells, and therefore in the underground part of the gas generator will be exhausted, the pressure in the underground gas generator will practically not change.

Special field experiments conducted in Belgium (Tulen) at a depth of 900 - 1000 m, it was shown that it is not possible to implement CCGT in the channel [E. Kreinin. Non-traditional thermal technologies for the extraction of hard-to-recover fuels: coal, hydrocarbon raw materials. Moscow, IRC Gasprom LLC, 2004, p. 91 - 94.]. The gasification channel was filled with coal fines, the gasification process was carried out by a filtration method, i.e. at elevated pressure up to 2.0 MPa and a limited flow rate of blast. Such a regime of gasification cannot be an industrial way of producing CCGT gas. The reason for filling narrow drilling channels with coal fines is the manifestation of rock pressure at great depths. No technical solutions have been proposed to compensate for rock pressure in the drilling channels of an underground gas generator. The prevention of environmental pollution of groundwater in the hydrosphere by thermal decomposition of coal was not considered at all.

As a result, in the 90s of the 20th century, the European Union decided to conduct CCGT experiments at a depth of 500 m (Northern Spain).

A well-known technical solution for the operation of narrow drilling channels in a coal seam is their fire expansion by countercurrent movement of the combustion site along the drilling channel towards the air blast [RU 2209984, 2003].

However, the implementation of this solution in conditions of high mountain pressure at great depths was not considered and was not proposed, especially taking into account the prevention of environmental pollution of groundwater.

Known hydrochemical studies [Kreinin E.V. Non-traditional thermal technologies for the extraction of hard-to-recover fuels: coal, hydrocarbon raw materials. Moscow, IRC Gasprom LLC, 2004, p. 177-182.] It was found that in the underground waters of the spent underground gas generator contained 7-8 mg / l of ammonium and 0.004 mg / l of phenols, which is 4-5 times higher than the maximum permissible concentration (MPC). In the practice of the Podzemgaz South-Abinsk station, these groundwaters were not purified, since according to the filtration mathematical model, the phenol concentration gradually (over time) decreased to the maximum permissible (0.001 mg / l). Special measures to neutralize groundwater and to clean from chemical pollutants were not provided. Phenols are especially dangerous from the group of chemical pollutants because of their relatively good solubility in water. Other chemical aromatic compounds are also dangerous. Deep cleaning methods can be divided into two main groups: regenerative and destructive. The most common destructive methods. The known method of ozonation for deep water purification from phenols [Galutkina KA, Nemchenko A.G., Rubinskaya E.V. etc. The use of the chemical oxidation method in the process of wastewater treatment of oil refining and petrochemical industries. Thematic review. Moscow, TsNIITENeftekhim, 1979.]. Using ozonation, it is possible to achieve wastewater treatment from phenols to a level close to MPC (0.05–0.001 mg / l). The disadvantages of the ozonation method include: the high cost of ozone, its toxicity, short lifetime of ozone molecules, etc.

The good oxidation of phenols in wastewater by atmospheric oxygen is also known. With proper technological parameters, the oxidation of phenols can be brought to the formation of CO ₂ and H ₂ O.

The destructive cleaning methods also include biological treatment. Its essence is the biochemical oxidation of organic (aromatic) and ammonium compounds in the presence of bacteria - mineralizers [Sharifullin B.H., Zitdinov N.N. Intensification of biochemical treatment of phenol-containing wastewater. Chemical industry. 2000, N ° 4, pp. 41-42.].

At the Podzemgaz South Abinsk station, concentrated gas condensate contained up to 2000 mg / l of phenols and 5000 mg / l of ammonium. After preliminary purification from resins and solid particles in sedimentation tanks, the purified water contained about 200 mg / l of phenols and up to 3000 mg / l of ammonium. For the final treatment, the wastewater was subjected to biochemical treatment used at metallurgical enterprises [Leibovich P.E., Obukhovsky Y.M., Satanovsky C.Ya. Technology of coke production. Moscow, Metallurgy, 1966, pp. 326-340]. The limiting features of this famous solution are:

- the need for wastewater treatment in the ground complex;

- the concentration of chemical pollutants in the underground waters of the spent gas generator is orders of magnitude lower than in the condensate recovered with CCGT gas, but still exceeds the corresponding MPC.

Disclosure of invention

The objective of the proposed group of inventions, united by a single inventive concept, is to create a comprehensive and universal solution aimed at preventing the pollution of groundwater by chemical pollutants, both generated in the process of coal gasification and remaining in the waste space of the underground gas generator.

The technical result is to minimize the migration of gasification products from an underground gas generator, and, consequently, a significant reduction in the possibility of groundwater pollution due to the creation of a system of reaction channels, including at a great depth (up to 1000 m), which allows underground coal gasification (CCGT) by the traditional and efficient flow method at low pressure (up to 0.3 MPa), as well as thin groundwater treatment directly in the waste space of the underground gas generator, which completed the operational operation.

The problem is solved and the technical result is achieved in one embodiment by the fact that in the method of environmentally friendly underground coal gasification, which consists in drilling a series of wells in the gasification section, combining the blow and exhaust pipes into a single underground gas generator with the initial gasification reaction channel by igniting the coal seam at assistance of transverse directional horizontal and vertical wells connected to it, preparation of gas vents and operation of blast wells in the process of gasification when controlling the pressure in the underground gas generator and adjusting the hydraulic regimes of the blast and gas outlet wells, controlling the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater using hydro-observation and drainage wells and lowering the hydrostatic level of groundwater by incorporating vertical wells that equip to the beginning of the gasification process as drainage and drainage wells, the gasification process was carried out consistently in two stages - injection at elevated pressure in the underground gas generator and injection and suction at minimum pressure in the underground gas generator, and when the concentration of chemical pollutants in underground waters increases in the water observation and / or drainage wells in the first stage of the gasification process, they increase the hydrostatic groundwater level by disabling drainage and drainage wells, and in the second stage of the gasification process, increase the productivity of drainage wells in and smoke exhausts in gas exhaust wells, while the underground waters selected by drainage and drainage wells are purified from chemical pollutants in the surface complex.

The first stage of the gasification process is carried out at elevated pressure in the underground gas generator, usually equal to approximately the pressure of the existing hydrostatic column of groundwater in the gasification section, for which the hydrostatic level of groundwater above the initial gasification reaction channel is fixed, and the reduction of this level is monitored during gas degassing using hydro-observation and drainage wells and, accordingly, reduce the pressure on the blast holes to 0.2 ÷ 0.3 MPa, then go to the second stage Processes gasification at the lowest pressure in the underground gas generator, which is fixed to the static pressure in the underground gasifier and include a work-otsosnuyu injection system. It contributes to the achievement of the technical result by the fact that before the start of the gasification process, directional wells are drilled along the coal seam at the lateral boundaries of the underground gas generator, connected to vertical wells and firing of the coal part of the directed directional wells is carried out by means of counterflow movement of the combustion site by blowing them, and to reduce the hydrostatic level of groundwater during gasification, their selection is carried out from directional wells of vertical wells, fitted to the top of the gasification process as dewatering.

As a rule, hydrostatic groundwater levels in the gasification section are recorded according to the data of hydraulic observation and drainage wells and a plot of the deposition funnel above and next to the underground gas generator is constructed from them, then these plots are used to adjust the hydraulic regimes of the blast and exhaust wells, as well as for determining the moments of inclusion or shutdown of drainage and sump wells.

After the end of the gasification process, in the presence of a residual concentration of chemical pollutants in the underground waters of the underground gas generator’s waste space exceeding the maximum permissible values, groundwater is purified using the biological method of decomposition and neutralization of pollutants.

The preparation of a gas outlet well of an underground gas generator, usually consists of drilling a well, consisting of a cased part, passed through rocks containing a coal seam, and performed in the form of a double metal column with a water supply in the annular gap between the pipes to supply water to the end of the cased part of the well and cooling of the exhaust hot gas through its inner pipe, as well as the unfrozen part, passed through the coal seam, and thermally worked out by means of a controlled counterflow the combustion zone along the drilling channel to meet the air blast injected into the well, while the water supply in the annular gap of the cased part of the gas outlet well is completed in the rock of the roof or soil near the boundaries of their contact with the coal seam, and the inner pipe of the cased part of the well is completed in the initial zone of the coal seam, moreover, the device for monitoring the position of the combustion zone in the gas well is placed at the end of its inner casing string, the movement of the combustion zone to it is recorded, and after moving it to column flue wellbore pumping amount blast air, and, hence, you are a gazovat coal under column flue wellbore to create a separator vessel is determined from a mathematical that is presented later in the description section "Bapianty embodiment)). ABOUT

Simultaneously with fixation of the combustion zone in the zone adjacent to the end of the column of the gas outlet well, water begins to be supplied to cool it.

After completion of the injection of air blast to create a separator tank, the gas exhaust well is gradually transferred from the mode of injection of air blast to the regime of intensive gas removal from the underground gas generator.

The operation of the blast holes of the underground gas generator consists in the controlled supply of the oxidizer to the hot coal surface along the length of the blast hole drilled and cased along the entire length, including along the coal seam, as well as fixing the burning center along its length, while fixing the burning center along the length of the blast hole carry out hydrodynamic control of the flow of air blast from the minimum at which the combustion focus is moved along the well towards the pumped blast to the maximum flow rate in which the burning center is fixed in the nearest zone of the hot coal surface of the seam and coal is emitted in it with high heat and energy indicators, and after the strip of the coal seam between the blast and gas outlet gas is exhausted at the maximum flow rate, the flow rate is reduced to the minimum and the burning center is moved towards the pumped air blast to a new zone of the blast hole, after which the blast flow rate is increased to the maximum and a fresh strip of the coal seam is gassed.

In the first commissioned blast hole of an underground gas generator, a control system is installed to control the movement of the combustion chamber towards the injected minimum flow rate of air blast, the dependence of the rate of countercurrent movement of the combustion zone on the flow rate of the air blast is determined and distributed to the operating modes of the remaining blast wells of the underground gas generator.

The gas degassing is controlled around each of the blast holes of the underground gas generator and ensure uniform advance of the fire face across the entire width of the gas generator.

A comparative analysis of the claimed solution with the well-known shows that the claimed method in the proposed set of essential features is formulated for the first time and gives the problem of minimizing groundwater pollution a universal character, which indicates its novelty.

The inventive method corresponds to an inventive step, because Distinctive features and their combination cover almost all possible ways of migration of chemical pollutants from an underground gas generator. In addition, specific ways of monitoring and adjusting the technological regime are being formed.

In another embodiment, the problem is solved and the technical result is achieved by the fact that according to the invention in a method of environmentally friendly underground gasification of coal lei, consisting in drilling a series of wells in the gasification section, casing them all the way, including rock and coal parts, connecting the blast and gas outlet wells into a single underground gasifier with the initial gasification reaction channel by igniting a coal seam using a transverse horizontal well and connected with it, at least one vertical well, the preparation of gas outlets and the operation of blast holes in the process of gasification while monitoring the pressure in underground gas generator and adjusting the hydraulic regimes of blast and gas outlet wells, monitoring the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater using hydro-observation and drainage wells and lowering the hydrostatic level of groundwater by including drainage wells and at least one vertical well , which is equipped at the beginning of the gasification process as a sump, the connection of blast and gas wells in a single underground The second gasifier with the initial gasification reaction channel is fired by firing up the casing and expanding the coal parts of the transverse directional horizontal and each of the gas outlet wells in turn, starting from the coal seam ignition site adjacent to the place, by countercurrently moving the combustion center by blowing them, after which go to the gasification process by degassing of the coal seam, while the removal of gasification products is initially carried out through at least one Vertical, hole, then through the borehole The exhaust gas, as selected, at least one drainage well bore and subterranean water is purified in the surface complex of chemical pollutants. Contributes to the achievement of the technical result that:

- in a specific example, the coal parts of the gas and lateral horizontal wells are cased to the entire length with a countersunk casing;

- usually the injection of blast into gas wells is carried out after the manifestation of signs of their connectivity with a transverse inclined horizontal well, which is fixed by the appearance of combustion products and static pressure on their heads;

- at least two vertical wells, of which are subsequently connected to a transverse inclined horizontal well, are located at the lateral boundaries of the underground gas generator;

- when predicting a large water inflow before the gasification process begins, lateral directional wells are drilled along the coal seam along the lateral boundaries of the underground gas generator, cased along their entire length, including rock and coal parts, connected to vertical wells located along the lateral boundaries of the underground gas generator, and fire development is carried out with flashing casing and the expansion of the coal parts of the directional wells by means of countercurrent movement of the combustion site by injection of blast in them, and to reduce the hydrostatic level of groundwater, they are selected from the directional wells through vertical wells located along the lateral boundaries of the underground gas generator, which are equipped to start gasification in quality of drainage;

- the coal parts of the obstruction directional wells are cased to the full length with a secret casing;

- the location of the combustion zone during its countercurrent movement and, accordingly, the melting of the casing strings are controlled by preliminary installation of heat-closing electric circuits connected to the surface with an electric measuring device;

- after the end of the gasification process, if there is a residual concentration of chemical pollutants in the underground waters of the underground gas generator’s waste space exceeding the maximum permissible values, the underground waters will be purified using the biological method of decomposition and neutralization of pollutants.

In addition, as the coal seam degasses along a transverse inclined horizontal well, the appearance of combustion products and the increase in static pressure on the heads of the gas outlet wells, which can be inclined or horizontal, respectively, for inclined and horizontal coal seams, are controlled, and after signs of their hydrodynamic connection with the reaction channel along an inclined horizontal well begin to pump air into these gas outlet wells Tie for countercurrent movement of the combustion zone and the expansion of their coal part.

In the process of such preparatory fire development of gas discharge wells, gas is initially removed through a vertical (fulfilling the function of an ignition) well, and then through directional or directional horizontal wells, which are gradually put into operation (after fire expansion). In this case, the casing is melted and the coal parts expand.

The preparation of a gas outlet well can be completed by creating an underground separator tank.

A comparative analysis of the proposed solution with the known ones shows that the claimed method in the proposed set of essential features is formulated for the first time and gives the problem of CCGT development, especially at great depths, while minimizing the migration of gasification products from the underground gas generator to a specific and universal nature, that is, it is new. The inventive method also corresponds to the inventive step, since the distinguishing features and their combination allow (in contrast to the negative experience of the mid 8Ox years of the XX century in the city of Tulen) under the conditions of high mountain pressure at a depth of 1000 m to carry out underground gasification in free coal channels.

The proposed method is illustrated by the schematic diagram of the underground gas generator module and the technological regulations for its preparation for operation in the presence of rock pressure.

The task is also solved and the technical result is achieved by the fact that in the method of groundwater purification in the waste space of an underground gas generator, characterized by the use of the biological method of decomposition and neutralization of chemical pollutants generated during coal gasification in a single underground gas generator with an initial gasification reaction channel and a series of wells including transverse oblique horizontal, blasting, venting and at least one vertical well s, after completing the process of coal gasification and filling the waste space of the underground gas generator with underground water, the bacterial medium is periodically introduced through the wells into the underground water of the underground gas generator waste space, and the type of bacteria of the bacterial medium is selected taking into account the composition and concentration of chemical pollutants in the underground water, for which from time to time, samples are taken through the wells and subjected to chemical analysis.

Contributes to the achievement of the technical result that:

- support an alkaline environment in the underground waters of the underground gas generator working space with pH = 7.5 ÷ 9 by supplying a solution of Na ₂ CO ₃ through the wells into the underground water working space of the underground gas generator;

- the volume of groundwater in the waste space of the underground gas generator is periodically mixed by forcing air into one well and discharging it through other wells;

- use ignition wells of the initial gasification reaction channel — transverse oblique horizontal and / or at least one vertical well as wells for air injection, and blow and / or gas outlet wells as air exhaust wells;

- the introduction of the bacterial medium into groundwater of the spent space of the underground gas generator is stopped after the concentration of chemical pollutants in them is below the maximum permissible values.

A comparative analysis of the proposed solution with the known shows that this method in the proposed set of essential features is formulated for the first time and allows groundwater treatment directly in the degassed gas the space of the underground gas generator, taking into account the use of its specific features for performing certain operations, which indicates its novelty.

The method also corresponds to the inventive step, since no solutions have been identified in the prior art, of which signs are known that allow the biological treatment of groundwater directly in the waste space of the underground gas generator using an environmentally friendly method.

Brief Description of the Drawings

The following is a description of the best ways to implement the proposed group of inventions.

In FIG. Figure 1 shows the dynamics of the migration of phenols and ammonia from the existing gas generator at the South Abinsk Podzemgaz station.

In FIG. 2 is a diagram of an underground gas generator (in the plane of a coal seam) in which the main features of the claimed method are implemented.

In FIG. 3 shows the module of the underground gas generator according to the proposed method in the initial stage of the gasification process - preparatory.

In FIG. 4 - the same in the final stage of the gasification process - the final one.

In FIG. Figure 5 shows the dynamics of the migration of phenols and ammonium from the spent gas generator of the Podzemgaz South-Abinsk station.

In FIG. 6 shows a schematic diagram of an underground gas generator that has completed its operation (in the plane of a coal seam).

In FIG. 7 shows the actual data on the concentration of phenols in groundwater extracted from the worked out space of the underground gas generator using a submersible pump and airlift.

Embodiments of the invention

Consider the main stages of the implementation of one of the options for an environmentally friendly underground coal gasification aimed at minimizing the migration of chemical pollutants from an underground gas generator. According to the actual data presented in FIG. 1, the underground gas generator is a source of chemical pollution of groundwater. Directly in the underground gas generator, the concentration of phenols reaches 0.1 mg / L and ammonium - 15 mg / L, which exceeds the MPC by 100 and 10 times, respectively. As the distance from the gas generator is 300-400 meters, the concentration of these pollutants approaches the maximum permissible.

The task is to find a way to minimize the migration of chemical pollutants outside the underground gas generator, which will save groundwater for drinking water supply.

SUBSTITUTE SHEET (RULE 26) In FIG. 2 presents such a technical solution to minimize groundwater pollution.

The method is as follows. At the gasification section, a series of wells is drilled, represented by gas outlet and blast wells 1,2, transverse oblique-horizontal 3, vertical (drainage) 4, hydro-observation and drainage wells 5, 6, respectively.

Gas exhaust and blast wells 1.2 are parallel located and directed along the coal seam. Wells 1.2 are connected into a single underground gas generator with the initial reaction channel for gasification by firing up a coal seam using a transverse oblique-horizontal 3 and vertical wells 4 connected to it.

With the expected large water inflows before the gasification process begins, the directional wells 7 are drilled along the coal seam along the lateral boundaries of the underground gas generator, connected to vertical wells 8, which are connected to the transverse inclined horizontal well 3, and, in order to obtain effective drains 9, they fire the development of the coal part of the barrier directional wells 7 by means of countercurrent movement of the combustion site by blowing them. Drilling of barrier directional wells 7 and subsequent connection with vertical wells 8 is carried out using modern navigation systems. If necessary, these wells 7 and 8 can be connected to each other by one of the known methods, for example, by hydraulic fracturing of a coal seam.

The drainage and drainage wells are equipped with 4.8.6 necessary water-lifting equipment, and 4.8 wells have hydraulic connection on the ignition horizon 10.

The preparation of gas wells 1 can be carried out as follows. Gas outlet wells 1 consist of cased and uncased parts. The cased part is passed through the rocks outside the zone of their displacement and is made in the form of a double metal column with a water supply placed in the annular gap between the pipes to supply water to the end of the cased part of the well and cool the exhaust hot gas through its inner pipe. The uncased part is passed through a coal seam. The water supply in the annular gap of the cased part of the exhaust well 1 is completed in the roof or soil rock near the nearest boundaries of their contact with the coal seam, and the inner pipe of the cased part of the well is completed in the initial zone of the coal seam. At the end of its inner casing string, a device is installed to control the position of the combustion zone in the exhaust gas well.

Thermal study of the uncased part of the exhaust well 1 is carried out by means of a controlled countercurrent movement of the combustion center along the coal -

SUBSTITUTE SHEET (RULE 26) channel to meet the air blown into the well. In this case, the moment of movement of the combustion zone to the end of the inner casing string is recorded, and after moving it to the casing of the gas outlet well, the amount of blown air blast, and, consequently, the gas degassed under the gas column to create the tank 11 of the underground separator is determined from the expression

YY _% = f _k -K.L.γ _y -B _g .υ _g , where: ^ V _g - amount of forced air blast, m; f _k - the average cross-sectional area of the worked open part of the gas outlet of the underground separator, m ² ; k is the coefficient of increase in the area of the passage section of the gas outlet of the underground separator;

L is the length of the gas part of the coal seam under the lower end of the inner pipe of the gas outlet well along its uncased part, m; γ _y is the specific gravity of the gas to be gased out, t / m ³ ;

B _g - specific gas output, m ³ / kg; υ _g - specific consumption of blast, m ³ / m ³ .

The value of the coefficient “l:” varies over a wide range from 50 to 150, while its minimum values are used for heat-resistant coal lying in dense rocks (for example, siltstones), and the maximum for heat-resistant coal (lean) lying in weak rocks ( e.g. sandstones, limestones).

In addition, in order to prevent overheating and deformation of the well string after the appearance of a combustion zone directly in the zone adjacent to the end of the gas outlet string, water is supplied to cool it. In the final stage of the preparation of the exhaust gas well 1, i.e. after the completion of the injection of air blast to create the tank 11 of the underground separator, the gas outlet 1 is gradually transferred from the injection mode of the air blast to the regime of intensive gas removal from the underground gas generator.

The gasification process is carried out sequentially in two stages - injection at elevated pressure in the underground gas generator and injection-suction at minimum pressure in the underground gas generator.

The first stage of the gasification process is carried out at elevated pressure in the underground gas generator, approximately equal to the pressure of the existing hydrostatic column of groundwater in the gasification section. For this, a hydrostatic uro the level of groundwater above the initial gasification reaction channel, during the formation of coal, a decrease in this level is monitored with the aid of observation and drainage wells 5.6 and, accordingly, pressure on the blast holes 2 is reduced to 0.2 ÷ 0.3 MPa. Then go to the second stage of the gasification process, which is carried out at a minimum pressure in the underground gas generator, for which they fix the static pressure in the underground gas generator.

Carry out constant monitoring of concentrations of chemical pollutants in groundwater. Moreover, if the concentration of chemical pollutants in underground waters in the first stage of the gasification process increases in 5.6 observing and / or drainage wells, they increase the hydrostatic level of groundwater by disabling drainage and drainage wells 4.8.6.

In the second stage of the gasification process, with an increase in 5.6 in the observation and / or drainage wells, the concentration of chemical pollutants in groundwater increases the productivity of 4.8 sump wells and smoke exhausters in gas extraction wells 1.

To reduce the hydrostatic level of groundwater during gasification, their selection is carried out from drainage and drainage wells 4.6, and from obstruction directional wells 7, which are thermally prepared drains 9 at the time of gasification, through vertical wells 8 equipped to start the gasification process as drainage.

4,8,6 groundwater taken by drainage and drainage wells is treated in a surface complex for chemical pollutants. In the process of gasification, they control the pressure in the underground gas generator and adjust the hydraulic regimes of the blast and exhaust wells 2.1, control the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater with the help of observation and drainage wells 5.6 and reduce the hydrostatic level of groundwater by inclusion of 4.8 (drainage) wells and drainage wells 6.

According to the data of hydro-observation and drainage wells, 5.6 record the hydrostatic levels of groundwater in the gasification area and plot diagrams of the depression funnel above and near the underground gas generator. Then these diagrams are used to adjust the hydraulic modes of the blast and gas outlet wells 2.1, as well as to determine the moments when the drainage 6 and drainage wells 4.8 are turned on or off.

The operation of the blast holes 2 consists in the controlled supply of air blast (oxidizer) to the reaction coal surface along the length of the cased blast wells 2, including and along the coal seam, as well as with the fixation of the burning center along its length. The combustion zone is fixed by hydrodynamic regulation of air blasting from the minimum at which the combustion zone is moved along the borehole towards the blast being blown up to the maximum flow rate at which the combustion zone is fixed in the nearest zone of the hot surface of the coal seam and coal is emitted in it with high heat and power indicators. At the same time, the technological regulation of the operation of the blast hole is carried out in the following sequence:

- gas strip strip of the coal seam between the blast and exhaust wells at the maximum flow rate of blast;

- reduce the consumption of air blasting to a minimum (700-900 m ³ / h) and move the combustion focus towards the pumped air blast to a predetermined new zone of the blast hole;

- increase the flow rate of the blast to the maximum and in the new zone, strip a fresh strip of coal seam.

In addition, the first injected blast hole 2 of the underground gas generator is equipped with a control system for the movement of the combustion focus towards the air blast. The dependence of the rate of movement of the combustion zone on the flow rate of air blast is determined and distributed to the operating modes of the remaining blast wells 2 of the underground gas generator. During the gasification of the coal seam, its outgassing around each of the blast holes 2 is controlled and the firing face is uniformly distributed across the entire width of the underground gas generator. The ignited zone of the coal seam moves along the path of the blast hole, providing controlled contact of the oxidizer with the reaction coal surface.

In a specific example of the method, after drilling a series of wells in the gasification section, the initial gasification reaction channel is formed, wells 1, 2 are connected into a single underground gasifier with the initial gasification reaction channel. To do this, ignite the coal seam using a transverse oblique-horizontal 3 and vertical wells 4 connected to it.

In particular, the coal seam is ignited in the bottom of a vertical well, for example, 4 or 8, located closer to the end part of the transverse inclined horizontal well 3 and, when the air blast 3 is fed into the well 3, the burning center moves towards air blast, forming the initial reaction channel for the gasification of a single underground gas generator on the horizon of the initial ignition.

Prepare gas wells 1, for example, with a capacity of 11 underground separator, as described above.

At the stage of preparatory work, if necessary, directional wells 7 are drilled along the lateral boundaries of the underground gas generator, cased before entering the coal seam, connected to vertical wells 8, and firing of the coal part of the directed directional wells 7 is carried out by counter-moving the burning focus injection of blast in them (1000 ÷ 1500 nm ³ / h). The burning center moves towards the air blast, forming a thermally prepared drain 9 with a diameter of 800-1000 mm with well-permeable side walls. The created artificial collector is a reliable drain for groundwater extracted using a pump, subsequently lowered into a vertical well 8, which is equipped as a drainage system at the beginning of the gasification process.

Simultaneously with the start of the gasification process, lateral drainage drains are included in the work 9. To monitor the position of the groundwater level and the concentration of chemical contaminants in them, water-observation wells are drilled in the gasification section 5. In addition, there are drainage wells 6 perforated throughout the underground gas generator and employees to drain the gasification area, including for preliminary drainage.

The technological regulations and the sequence of the proposed method are as follows. As an example of consideration, we take a gasification section where there was no preliminary drainage and the hydrostatic level of groundwater is close to the surface mark. By covering the gate valve at the head of the gas outlet well 1, the pressure of the blast injection into the well 2 is set to a value close to the pressure of the hydrostatic column of groundwater existing in the gasification section. In FIG. 2, this level is designated as I and corresponds to 200 m above the initial ignition horizon (the coal part of the transverse deviated horizontal well 3).

Pumps on sump wells 4.8 are turned on. The existing groundwater level is starting to decline. As it decreases, the valves in the gas outlet wells 2 are opened and, as a result of this, the pressure in the underground gas generator is reduced, and, therefore, the pressure in the blast holes 2. The decrease in groundwater level is monitored by observation and drainage wells 5.6.

After lowering the groundwater level to level II, corresponding to a mark of 150 m above the initial ignition horizon, the pressure in the underground gas generator is set to approximately 1.5 MPa. And so, consistently lowering the hydrostatic level groundwater in an underground gas generator to 100 m (W), 50 m (GV) and, finally, 25 m (V), reduce the pressure on the blast holes 2 and in the underground gas generator, to about 1.0 MPa, 0.5 MPa and 0.2 ÷ 0.3 MPa, respectively. Pressure 0.2 ÷ 0.3 MPa corresponds to the pressure of air for gasification by low pressure blowers.

This completes the injection stage of the CCGT unit and the second stage is realized - injection-suction gasification. To do this, include 1 exhaust fans (not shown) at the gas outlet wells and, thereby, reduce the pressure in the underground gas generator, and, therefore, minimize leakage of gasification products from it and, thereby, pollution of underground waters and the hydrosphere as a whole.

At the same time, water observation and drainage wells 5.8 are used not only for monitoring the position of the groundwater level (I-GV), but also for the concentration of chemical pollutants (gasification products) in them. In the injection stage, with an increase in the concentration of chemical pollutants, the hydrostatic level of groundwater is increased by turning off the pumps in drainage and drainage wells 4,8,6. In the injection-suction stage of gasification, in this case, the productivity of the pumps in the drainage wells 4.8 is increased and, at the same time, the capacity of the smoke exhausters in the exhaust wells 1 is increased.

As noted above, according to the data of hydro-observation 7 and drainage 8 wells, the position of the groundwater level in the gasification section of the coal seam is recorded. According to these data, diagrams of a depression funnel are constructed in the region of an underground gas generator. In FIG. Figure 2 shows in a simplified form the change in such plots of groundwater level (I-V) during the CCGT process (dashed lines). According to the constructed diagrams, the staff of the underground gas generator adjusts the hydraulic mode at the blast and exhaust wells 2.1, and also makes a decision on whether to turn pumps on or off in drainage and drainage wells 4,8,6.

The considered example of the application of the proposed method of environmentally friendly CCGT is a reliable means of preserving the hydrosphere in the area of gasification of a coal seam from pollution of groundwater.

The implementation of this method is provided for in production instructions and documents for introducing a new (environmentally friendly) CCGT technology.

Consider the main stages of the implementation of the second version of the proposed method of environmentally friendly underground coal gasification. The traditional design of the underground gas generator consists of a series of parallel-located oblique-horizontal gas outlet and blast wells 1, 2. Their paths intersect with a transverse oblique-horizontal well 3. Drilled vertical wells 4, which are connected to an oblique-horizontal well 3, as well as observation, drainage and overseas

SUBSTITUTE SHEET (RULE 26) Directional coal seam wells are 5.6.7, respectively. At the intersection of the horizontal section of the horizontal inclined well 3 and the extreme gas outlet wells 1 (along the lateral boundaries of the underground gas generator), vertical wells 8 were drilled, which are also connected to the horizontal inclined well 3.

The blast and gas outlet wells 2.1 intersect with a transverse inclined horizontal well 3 at the ignition horizon 10, while the gas outlet wells 1 may have tanks 11 of an underground separator (FIG. 3).

In a single underground gas generator with the initial reaction channel 12 of gasification are connected blast and exhaust wells 2.1.

Barrier directed along the coal seam wells 7 are connected to vertical wells 8. Thermally prepared drains 9 are made in the coal parts of the wells 7 (FIG. 4).

The final stage of the final (final) gasification is represented by the end line 13 of the outgassing of the coal seam, limiting the waste space (gaseous volume) 14.

The method is as follows. A series of wells are being drilled. Wells 1,2,3,7 of the underground gas generator: gas discharge, blow, horizontal inclined, including obstruction directed along the coal seam (if any) are cased to the entire length, including the rock and coal parts, and the coal part (~ 300 in length) m) gas outlet 1, inclined-horizontal (~ 320 ÷ 400 m long) 3 and blocking wells directed along the coal seam (-300 m long) 7 are blocked by a free pipe, for example, a secret pipe string (shown in dashed lines), with a diameter slightly smaller drill pipe diameter ala. Vertical wells 4, 8 are cased and completed in a coal seam. Observation and drainage wells 5.6 are constructed in the usual way. Drainage wells 6 are usually perforated over the entire length and are used to drain the gasification area, including for preliminary drainage. Between the wells 1, the distance can be ~ 80 ÷ 100 m.

Drilling of barrier directional wells 7 and subsequent connection with vertical wells 8, as well as other wells 1,2,3,4, is carried out using modern navigation systems and a technological tool known to specialists.

In the bottom of a vertical well, for example, 4 or 8, a coal seam is ignited and high pressure air is injected to develop a high-temperature ignited zone. Simultaneously with the ignition of the coal seam, pressure is monitored on the heads of the closed wells 1 and 3 and periodically take gas samples from them for chemical analysis. After the appearance of coal combustion products in the samples taken, as well as the growth of static

SUBSTITUTE SHEET (RULE 26) pressure at the heads of these wells, they begin to pump air blast in the amount of 800 ÷ 1000 m ³ / h. Gas is removed through a vertical well 4 and / or 8.

As a result of countercurrent movement of the combustion zone, the borehole of the borehole 3 expands to 1000 mm and the column is melted at the same time (the figures are shown by two dashed lines). An initial gasification reaction channel 12 is created.

According to a special experiment conducted at the Podzemgaz South-Abinsk station on a gas generator N ° 18, at an air flow rate of 1700 m ³ / h, the speed of movement of the burning center towards the blast was about 1 m / h. In this case, the well was cased and cemented to its full length, the length of the casing along the coal seam was 183 m.

It is characteristic that in a clean (open-cased) coal channel at an air flow rate of 1740 m / h, the countercurrent velocity of the combustion site was 1.66 m / h.

The control of the location of the combustion zone, moving along the coal part of the wells 3 and 1, is carried out in a known manner using heat-closing electrical circuits connected to the surface with an electric measuring device [RU 2236599, 2004]. This well-known tool is an electric wire for the entire length of the well, along the length of the wire soldered (after 20 ÷ 40 m) devices filled with fusible metal (for example, Wood alloy). When the combustion zone approaches this device and it is heated to 60 ÷ 70 ° C, the alloy goes into a liquid state and the electric circuit closes. The occurrence of a closed electrical circuit is fixed on the surface by an electric measuring device.

After completion of the fire study of the extreme gas outlet well 1. it is gradually transferred from the air injection mode to the gas exhaust mode, while the vertical well with the help of which the coal seam was ignited is either closed or switched to the blast mode.

In the presence of directional wells 7 in the gasification section, their firing study with the melting of the casing strings and the expansion of the coal parts is carried out using vertical wells 8 in a similar manner.

After the blast and gas outlet wells 2.1 are connected into a single underground gas generator with the initial gasification reaction channel 12, gas outlet wells 1 are prepared, 4.8 vertical wells are equipped as drainage wells, and the most productive phase of the coal seam gasification process is set up.

As the gas is gassed along the transverse horizontal channel 3, all blast and exhaust wells 2.1 are commissioned in turn. Moreover, their hydraulic connection with the initial gasification reaction channel 12 (FIG. 3) is controlled by measuring the static pressure and gas composition on the closed heads of these wells.

SUBSTITUTE SHEET (RULE 26) Jin. Earlier in the text, this control operation was described in relation to the period of the firing study of the coal part of well 3 and the extreme well 1.

The commissioning of new blast and gas exhaust wells 2.1 allows us to intensify the process of gas degassing within the underground gas generator and gradually enter industrial production rates: blast well - 8-10 thousand (SOOO ÷ YuOOO) m ³ / h; gas outlet well - 10 ÷ 12 thousand (1000Q ÷ 12QOO) m ³ / h.

To reduce the hydrostatic level of groundwater during gasification, their selection is carried out from drainage and drainage wells 4.6, and from obstruction directional wells 7 (if any), which are thermally prepared drains 9, through vertical wells 8 equipped to start the gasification process as a sump.

The 4.8.6 underground water taken by drainage and drainage wells is cleaned from the surface complex from chemical pollutants.

In the process of gasification, they control the pressure in the underground gas generator and adjust the hydraulic regimes of the blast and exhaust wells 2.1, control the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater, using hydro-observation and drainage wells 5.6 and reduce the hydrostatic level of groundwater by including in the work of vertical (sump) wells 4.8 and drainage wells 6.

After the end of the gasification process, in the presence of a residual concentration of chemical pollutants in the underground water of the underground gas generator spent space exceeding the maximum permissible values, the underground water is purified using the biological method of decomposition and neutralization of pollutants.

Thus, the overlapping of the drilling channels in the coal part with a metal column and their subsequent development (expansion) by countercurrent movement of the combustion zone allow the CCGT process to be carried out in the reaction channels, which was not possible in the project in Tulen (Belgium) at a depth of about 1000 m from -for the negative manifestation of rock pressure (filling the drilling channel with coal fines).

Thus, the claimed invention allows to realize the main advantage of CCGT unit - the deserted development of coal seams by converting them into combustible gas at depths of 500 ÷ 10,000 and more than meters while minimizing the migration of gasification products from an underground gas generator.

The third object of the proposed group of inventions relates to a method for purifying groundwater in the waste space of an underground gas generator. Consider the presented illustrations of the proposed method. According to the actual data given

SUBSTITUTE SHEET (RULE 26) in FIG. 5, the concentration of ammonium and phenols in the center of the stopped gas generator is 7 and 0.0042 mg / l, respectively, and only at a distance of 200 m their values decrease to the maximum allowable concentrations of 2 and 0.001 mg / l, respectively.

The task is to find a way to minimize the concentration of the mentioned pollutants to MPC directly in the spent space of the underground gas generator.

The fragment of an underground gas generator (FIG. B) shows a series of wells of a single underground gas generator with an initial gasification reaction channel represented by gas outlet and blast wells 1,2, which can be directional or directional-horizontal, respectively, for inclined and horizontal coal seams. Blast and gas discharge wells 2.1 are initially intersected by a transverse deviated horizontal well 3, to which vertical wells 4 are connected.

Gassed (waste) space (gassed volume) 14 is filled with ash, collapsed roof and groundwater.

The method is as follows.

After the coal gasification process is completed and the coal bed degassing line is moved from the initial gasification reaction channel (horizontal section of the transverse inclined horizontal well 3) to the coal seam end gasification line 13, the degassed volume 14 is filled with groundwater. Given the heated state of the roof and soil rocks in the gas-vented space, the presence of a hot coal surface at the final stage of gasification, as well as the absence of condensate removal from the exhaust wells 1, the concentration of chemical pollutants in the underground water of the degassed volume 14 remains above the MPC (FIG. 5).

The proposed method solves the problem of neutralizing contaminated groundwater directly in the spent underground gas generator (FIG. 6). In this case, the main attention is paid to phenols, a distinctive feature of which is good solubility in water, and ammonium. In the presence of mineralizing bacteria, aromatic organics and ammonium nitrogen undergo biochemical oxidation (cleavage).

According to the proposed method, the bacterial medium (special bacteria) is introduced into the production wells of the spent gas generator. Bacteria are spontaneously distributed in the amount of groundwater that fills the spent space 6 of the underground gas generator. Enzymes produced by bacterial microorganisms catalyze the biochemical oxidation (breakdown) of phenols. Depending on composition and concentration

SUBSTITUTE SHEET (RULE 26) chemical pollutants determined in periodically selected groundwater samples from the wells of an exhaust gas generator use mainly two types of microorganisms: activated sludge, which is a complex of simple bacteria, and cultures of specific bacteria with highly effective phenol-destroying properties. Other bacterial options are possible. At the same time, bacteria from a single underground gas generator with the initial gasification reaction channel (transverse inclined horizontal 3, vertical 4, as well as blast and exhaust wells 2.1) are used to enter bacteria.

The introduction of bacteria is periodically repeated as the developed space is filled with 14 underground waters.

The creation of an alkaline environment (pH = 7.5 ÷ 9), which ensures the most active cleavage of phenols, is achieved by introducing a solution of Na ₂ CO ₃ through the wells 14.

To average the composition of groundwater in the worked-out space 14 of the underground gas generator, including bacteria and Na ₂ CO ₃ introduced into it, the volume of groundwater must be mixed. For this purpose, air is supplied periodically to some wells, for example, ignition channels of the initial gasification reaction channel (transverse directional horizontal 3, vertical 4 wells), and it is vented through other wells, for example, blast and gas outlet wells 2.1. At the same time, the indicated air supply and exhaust scheme is more preferable (better conditions for sparging are created), since air is introduced at the ignition horizon, and the output is at the end line 13 of the outgassing of the coal seam, at which lower ends are located at this point (final gasification stage) wells 1.2.

Sparging air through a layer of groundwater intensifies their biochemical treatment. So, according to a specially conducted experiment at the industrial gas generator of the Podzemgaz South-Abinsk station, a decrease in the concentration of phenols in groundwater taken from the well by airlift was recorded compared with the option of pumping water out of the pump. From the experimental data in FIG. 7 it follows that in the first case, the concentration of phenols in the extracted water is 3-5 times lower than when it is pumped out by a pump.

After reducing the concentration of chemical pollutants to the MPC level, the bacterial recharge of groundwater is stopped, and control over their composition is continued for some time.

If there are other wells in the gasification section (hydro-observation, drainage, and barrier), underground water samples are also taken from them to determine the composition and concentration of chemical pollutants.

SUBSTITUTE SHEET (RULE 26) The implementation of the proposed method of neutralizing groundwater in an underground gas generator after completion of its operation solves one of the important environmental problems. After gassing of the coal seam by the CCGT method, the hydrosphere remains clean, meeting the requirements of drinking water supply.

Industrial applicability

The inventions of the group are so connected that they form a single common inventive concept, since the technical solutions disclosed in them form a single integrated and universal technological process aimed at preventing pollution of groundwater by chemical pollutants, both generated in the process of coal gasification and remaining in the waste space of an underground gas generator . The industrial applicability of the proposed technical solutions is confirmed by the described embodiments. In addition, the proposed technology was used in the projects of CCPP enterprises, as it provides the required environmental cleanliness.

Claims

CLAIM

1. A method of environmentally friendly underground coal gasification, which consists in drilling a series of wells in a gasification section, connecting blast and gas outlet wells into a single underground gasifier with an initial gasification reaction channel by firing a coal seam using a transverse directional horizontal and vertical wells connected to it, preparing gas outlet and operation of blast holes during gasification while monitoring the pressure in the underground gas generator and adjusting g hydraulic modes of blast and gas outlet wells, monitoring the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater using observation and drainage wells and lowering the hydrostatic level of groundwater by incorporating vertical wells that are equipped to start gasification as drainage and drainage wells, while the gasification process is carried out sequentially in two stages - injection at elevated pressure in underground azo generator and injection-suction pump with minimal pressure in the underground gas generator, and when the concentration of chemical pollutants in underground waters in the water observation wells increases in the observation water and / or drainage wells in the first stage of the gasification process, they increase the hydrostatic level of groundwater by shutting off drainage and drainage wells, and in the second stage gasification process - increase the productivity of drainage wells and smoke exhausters at exhaust gas wells, while selected by drainage and drainage and wells, groundwater is subjected to purification in the surface complex of chemical pollutants.

2. The method according to p. 1, characterized in that the first stage of the gasification process is carried out at elevated pressure in the underground gas generator, approximately equal to the pressure of the existing hydrostatic column of groundwater in the gasification section, for which the hydrostatic level of groundwater is fixed above the initial gasification reaction channel, during gas degassing, they control the reduction of this level with the help of observation and drainage wells and, accordingly, reduce the pressure on the blast holes to 0.2 ÷ 0.3 MPa, then m go to the second stage of the gasification process with a minimum pressure in the underground gas generator, for which they fix the static pressure in the underground gas generator.

3. The method according to p. 1, characterized in that before the start of the gasification process, directional wells are drilled along the coal seam along the lateral boundaries of the underground gas generator, connected to vertical wells and firing of the coal part of the directed directional wells is performed by countercurrent displacements of the combustion zone by injection of blast in them, and to reduce the hydrostatic level of groundwater during gasification, they are selected from defensive directed wells through vertical wells equipped as drainage to the beginning of the gasification process.

4. The method according to p. 1, characterized in that hydrostatic levels of groundwater are recorded on the gasification site according to the data of hydro-observation and drainage wells and the plots of the depression funnel are constructed above and below the underground gas generator, then these plots are used to adjust the hydraulic modes of the blast and gas outlet wells, as well as to determine when to turn on or off drainage and drainage wells.

5. The method according to any one of paragraphs. 1-4, characterized in that after the end of the gasification process, in the presence of a residual concentration of chemical pollutants in the underground waters of the underground gas generator working space exceeding the maximum permissible values, the underground waters are purified using the biological method of decomposition and neutralization of pollutants.

6. The method according to p. 1, characterized in that the preparation of the gas outlet of the underground gas generator consists in drilling a well, consisting of a cased part, passed through the rocks containing the coal seam, and performed in the form of a double metal column placed in an annular gap between the pipes a water supply pipe for supplying water to the end of the cased part of the well and cooling the exhaust hot gas through its inner pipe, as well as the uncased part, passed through the coal seam, and thermally worked out by controlling continuous countercurrent movement of the combustion zone along the drilling channel towards the air blast injected into the well, while the water supply in the annular gap of the cased part of the gas outlet well is completed in the rock of the roof or soil near the boundaries of their contact with the coal seam, and the inner pipe of the cased part of the well is completed in the initial zone of the coal formation, and a device for monitoring the position of the combustion zone in the gas well is placed at the end of its inner casing string, the movement of the hearth is recorded tions thereto, and after moving it to the column number of the discharge flue hole blast air, and, consequently, of coal under the column vygazovannogo flue wellbore to create a separator vessel is determined from the expression:

where: ^ TV _g is the amount of forced air blast, m ³ ;

f _k - the average sectional area of the worked open part gas outlet wells of the underground separator, m ² ; k is the coefficient of increase in the area of the passage section of the gas outlet of the underground separator;

L is the length of the gas part of the coal seam under the lower end of the inner pipe of the gas outlet well along its uncased part, m; γ is the specific gravity of the gas to be degassed, t / m ³ ;

7. The method according to p. 6, characterized in that at the same time as fixing the hotbed in the zone adjacent to the end of the column of the gas well, water is supplied to cool it.

8. The method according to p. 6 or p. 7, characterized in that after completion of the injection of air blast to create a separator tank, the gas outlet well is gradually transferred from the mode of injection of air blast to the mode of intensive gas removal from the underground gas generator.

9. The method according to claim 1, characterized in that the operation of the blast holes of the underground gas generator consists in the controlled supply of the oxidizing agent to the hot coal surface along the length of the blast hole drilled and cased along the entire length, including along the coal seam, as well as fixing the focus burning along its length, while fixing the burning center along the length of the blast hole is carried out by hydrodynamic control of the flow of air blast from the minimum at which the burning center is moved along the well towards the pumped by blasting, to the maximum flow rate at which the burning center is fixed in the nearest zone of the hot coal surface of the formation and gas is emitted in it with high heat and energy indicators, and after gasing the strip of the coal formation between the blast and gas outlet wells at the maximum blowing rate, its consumption is reduced to the minimum and move the combustion chamber towards the injected air blast to the new zone of the blast hole, after which the blast flow rate is increased to the maximum and the fresh strip at ol formation.

Yu.Sposob according to claim 9, characterized in that in the first commissioned blast hole of the underground gas generator, a control system for moving the combustion hearth towards the injected minimum flow rate of the air blast is placed, the dependence of the countercurrent velocity of the combustion hearth on the flow rate of the air source is determined blast and extend it to the operating modes of the remaining blast wells of the underground gas generator.

11. The method according to p. 9 or p. 10, characterized in that they control the degassing of coal around each of the blast holes of the underground gas generator and ensure uniform advancement of the fire face across the entire width of the gas generator.

12. A method of environmentally friendly underground coal gasification, which consists in drilling a series of wells in the gasification section, casing them all the way, including rock and coal parts, combining the blow and exhaust pipes into a single underground gas generator with the initial gasification reaction channel by igniting the coal seam using a transverse inclined horizontal well and at least one vertical well connected to it, preparing gas vents and operating blast wells in the process of gasification while monitoring the pressure in the underground gas generator and adjusting the hydraulic regimes of the blast and gas outlet wells, monitoring the hydrostatic level of groundwater and the concentration of chemical pollutants in groundwater using hydro-observation and drainage wells and lowering the hydrostatic level of groundwater by including drainage wells and, by at least one vertical well, which is equipped at the beginning of the gasification process as a sump, with the blast and gas outlet wells are combined into a single underground gas generator with the initial gasification reaction channel by firing through the melting of the casing and expanding the coal parts of the transverse inclined horizontal and each of the gas outlet wells alternately, starting from the adjacent coal seam ignition site, by means of countercurrent movement of the combustion focus injection of blast in them, after which they go on to the gasification process by degassing of the coal seam, while the removal of gasification products uu initially carried out through at least one vertical well bore, then through the borehole The exhaust gas, and the selected drain and at least one drainage boreholes underground water is purified in the surface complex of chemical pollutants.

13. The method according to p. 12, characterized in that the coal parts of the transverse inclined horizontal and gas wells are cased to the entire length with a countersunk casing.

N. The method according to claim 12, characterized in that the injection of blast into the exhaust wells is carried out after the signs of their connectivity with the transverse inclined horizontal well, which are fixed by the appearance of combustion products and static pressure on their heads,

15. The method according to p. 12, characterized in that at least two vertical wells from the number connected to the transverse inclined horizontal well, are located on the lateral boundaries of the underground gas generator,

16. The method according to p. 15, characterized in that before the start of the gasification process, directional wells are drilled along the coal seam along the coal seam, cased along the entire length, including rock and coal parts, connected to vertical wells located at the lateral borders underground gas generator, and carry out firing study with the melting of the casing strings and the expansion of the coal parts of the obstruction directional wells by countercurrent movement of the combustion site by injection into n their blasting, and to reduce the hydrostatic level of groundwater, they are selected from directional wells through vertical wells located along the lateral boundaries of the underground gas generator, which are equipped as drainage systems to the beginning of the gasification process.

17. The method according to clause 16, characterized in that the coal parts of the directional directional wells are cased to the entire length with a countersunk casing.

18. The method according to any one of paragraphs.12-17, characterized in that the location of the combustion site during countercurrent movement and, accordingly, the melting of the casing strings are controlled by pre-installing heat-closing electrical circuits connected to the surface with an electrical measuring device.

19. The method according to any one of paragraphs. 12-17, characterized in that after the end of the gasification process, in the presence of a residual concentration of chemical pollutants in the underground waters of the underground gas generator working space exceeding the maximum permissible values, the underground waters are purified using the biological method of decomposition and neutralization of pollutants.

20. A method of purification of groundwater in the waste space of an underground gas generator, which consists in using the biological method of decomposition and neutralization of chemical pollutants generated in the process of coal gasification in a single underground gas generator with an initial gasification reaction channel and a series of wells, including transverse oblique-horizontal, blasting, exhaust and at least one vertical well, according to which, after completion of the process of gasification of coal and filling about the worked space of the underground gas generator by groundwater, the bacterial medium is periodically introduced through the wells into the underground water of the worked space of the underground gas generator, while the type of bacteria of the bacterial medium is selected taking into account the composition and concentration of chemical pollutants in the underground water, for which their samples are periodically taken through the wells and subjected to chemical analysis.

21. The method according to claim 20, characterized in that an alkaline medium with pH = 7.5 ÷ 9 is maintained in the underground waters of the underground gas generator working space by supplying a solution of Na ₂ CO ₃ through the wells into the underground water working space of the underground gas generator working space.

22. The method according to item 21, wherein the volume of groundwater in the waste space of the underground gas generator is periodically mixed, forcing air into one well and discharging it through other wells.

23. The method according to p. 22, characterized in that the ignition wells of the initial gasification reaction channel — transverse oblique horizontal and / or at least one vertical well — are used as wells for injecting air, and as air extraction wells, blast and / or gas exhaust wells.

24. The method according to any one of claims 20-23, characterized in that the introduction of the bacterial medium into the underground waters of the spent space of the underground gas generator is stopped after the concentration of chemical pollutants in them is below the maximum permissible values.