EA013445B1 - Coalfield underground mining and method therefor - Google Patents

Abstract

The invention concerns mining engineering and may be used in the process of coal deposit development to secure safety of mining by underground and other methods and hydrocarbon gas preproduction mining. The objective of the invention is to increase effectiveness of coal mining with extraction of hydrocarbon gases and to reduce the risk of instantaneous outbursts and explosions of air-methane mixture in mines during mining operations. Underground mining of coalfield involving coal deposit uncovering by wells and forced feed of air-gas mixtures and/or liquids inwards the deposit with the help of instrumental methods includes detection of the highest hydrocarbon gas concentration areas in the deposit. According to gas-bearing capacity and permeability of these areas, the deposit is divided into blocks, from the land surface of each block injection and production wells are distantly drilled and then equipped with Christmas tree and pumping and compression pipes. The injection well is additionally equipped with a wave radiator. From the injection well several inclines are sunk, then cased with perforated pipes and equipped with wave deflectors and packers. Through the pumping and compression pipes into the coal bed the air-gas mixture and/or liquid are fed under pressure with simultaneous superposition of elastic waves for which the mixture and/or liquid serve as awaveguide. The elastic waves are oriented by a wave deflector and a packer towards the production well, from which hydrocarbon gas is taken, the coalfield treated blocks are developed by the underground technique.

Description

The invention relates to mining and can be used in the development of coal deposits to ensure the safety of mining by mine and other methods and associated production of hydrocarbon gases.

A known method of opening a coal seam for methane production, including opening a coal seam with a well drilled by its dip, with the addition of additional horizontal shafts along the strike of the coal seam at a calculated distance between them equal to the effective radius of the horizontal shafts [1] is an analog.

This method is ineffective, since it assumes high natural porosity and permeability for the mineral being developed, and coal has relatively low porosity and permeability. Methane, located in its pores and cracks under reservoir pressure, is a real threat to the life of miners due to sudden emissions and explosions of air-methane mixtures in mine conditions during mining operations.

There is also known a method of in-situ gas production from coal seams, in which to create gas paths in the coal, the structure of the gas-bearing coal is opened by gases and / or liquids supplied under pressure through the well drilled into the coal seam. Then, gas is generated in this borehole to produce gas. Its value is less than the corresponding measured desorption pressure. According to the invention, for opening a coal seam in a well for a period of time ranging from one day to several days or weeks, pressure is created to open a system of cracks in the coal seam, from macropores to microporous structures. The pressure value is taken less than the smallest principal stress measured in the corresponding coal seam horizon intended for gas production. Moreover, during the specified allotted period for the formation, the amount of pressure created in the well cyclically change [2] - prototype.

This method is also ineffective and does not provide safe mining of minerals and hydrocarbon gases, has a small radius of coverage for gas evolution from the reservoir due to the relatively low porosity and permeability of coal seams, which requires the drilling of many gas wells.

The method is also costly in view of its time inertness, energy losses for creating and maintaining for a long period of time the pressure of gases and / or liquids in the zone of gas-bearing coal production, and energy losses for creating gas release conditions from the reservoirs will go on throughout the entire field development period . The use of carbon dioxide CO ₂ and other hazardous mining working substances can lead to their release into the mine space during subsequent development of the field and cause poisoning or death.

The objective of the proposed invention is to increase the efficiency of development of coal deposits with the production of hydrocarbon gases and reduce the risk of sudden emissions and explosions of air-methane mixtures in mines during mining operations.

The problem is achieved in that in a method that includes opening a coal deposit with wells and supplying under pressure inside the deposit air-gas mixtures and / or liquids that are not dangerous to human life and health, using various methods, for example, geophysical, determine areas in a coal deposit with the highest content of hydrocarbon gases, depending on the gas content and permeability of these areas, break the deposit into blocks by calculation, drill from the ground surface of each block to the calculated depth at the calculated distance each of the injection and pumping wells, they are equipped with fountain fittings and tubing, and the injection is additionally a wave emitter, several obliquely oriented shafts pass from the injection well through the coal seam, they are surrounded by perforated pipes and equipped with wave reflectors and packers, and pump and the compressor pipes are fed into the coal seam under pressure, an air-gas mixture and / or liquid with the simultaneous application of elastic waves, for which she / they serve as a waveguide, elastic waves they are oriented by the wave reflector and the packer towards the pumping well, thus, the calculated permeability of the gas-bearing mineral is induced on the inter-well section of the block, the squeezed hydrocarbon gas is taken from the pumping well, the processed blocks of the coal deposit are developed by the underground method.

In FIG. 1 and 2 presents a flow chart of the proposed method for underground mining of coal deposits.

The proposed method is as follows.

Within the boundaries of coal deposit 1, various methods, for example, geological or geophysical, are used to study the gas content and permeability of a coal seam. Based on the results obtained and using the calculations, the coal deposit 1 is conventionally divided into separate blocks 3. At least two wells are drilled from the surface of the earth 5 to the design depth 4 at the boundaries of each block 4: injection 6 and pumping 7. The distance between the wells is determined by calculations depending on gas content and permeability of the treated area of the coal deposit 2. The wellheads are equipped with fountain fittings 8, and the injection well 6 is additionally equipped with a wave emitter 9, which can be placed on the mouth or in the well itself not. From injection well 6 using coiled tubing 10

- 1 013445 in the processed section of the coal seam 2 there are several obliquely oriented trunks 11. The length of the trunks 11 and the mark of their bottom are determined by calculations and depends on the size of the block 3 and the permeability of the treated section of the reservoir 2. The trunks 11 are lined with perforated pipes and equipped with tubing 12 with a wave reflector 13 and a packer 14. In the injection well 6 under pressure through the fountain fittings 8 and tubing 12 serves a gas-air mixture and / or liquid not dangerous to human health and life th simultaneous superposition of elastic waves, for which she / they serve as a waveguide. The direction of the elastic waves is oriented with the help of a wave reflector 12 and a packer 13 towards the pumping well 7. Thus, additional permeability of the processed section of the deposit 2 is induced. Squeezed out hydrocarbon gas for its utilization and use for various needs is carried out from the pumping well 7. Processed alternately ( or at the same time) blocks 3 of coal deposit 1 are developed by the mine method.

Thus, the use of the proposed method will effectively develop coal deposits, reduce the risk of sudden emissions and explosions of air-methane mixtures in mines and save the lives and health of miners, receive hydrocarbon gases for their use in the national economy.

Claims (1)

CLAIM A method of underground mining a coal deposit, including opening a coal deposit with wells and supplying pressurized air-gas mixtures and / or liquids into the reservoir, characterized in that, using instrumental methods, the areas with the highest content of hydrocarbon gases are determined in the coal deposit, depending on the gas content and the permeability of these sections break the deposit into blocks, from the surface of the earth of each block, drill and pump wells are drilled at a distance from each other, equip them with fountain fittings and pine tubing; and the injection one - additionally with a wave emitter, several obliquely oriented shafts pass through the coal seam from the injection well, surround them with perforated pipes and equip them with wave reflectors and packers, air-gas mixture and / or liquid with pressure are fed into the coal seam under pressure the simultaneous application of elastic waves, for which the mixture and / or liquid serves as a waveguide, the elastic waves are oriented by the wave reflector and packer towards the pumping well, from which tons of squeezed hydrocarbon gas, and the processed blocks of coal deposits are developed underground.