RU2564888C1 - Method of hydraulic coal mining from gas-bearing formations - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method of hydraulic coal mining from gas-bearing formations is offered which consists in field opening by wells, destruction and transfer of mineral into hydromix, mixing, sedimentation of dead rock on the bottom of the formed cavity, pumping out of water coal suspension to the surface and its transportation by pipes to consumers. The preliminary degassing and pressure relief of overlying and underlying outburst coal beds and the containing rock mass are performed by borehole coal mining from the formation dangerous by emissions of rock coal and gas taken as protective one. The mining wells are arranged so that boundaries of protective zones of the developed formation to be arranged evenly along the protected formations.

EFFECT: improvement of safety of mining operations when developing suite of gas-bearing coal beds.

2 dwg

Description

The invention relates to underground mining of mineral deposits prone to sudden emissions of coal and gas, and in particular to the downhole development of coal deposits.

There is a method of developing gas-saturated coal seams using advanced underground mining of protective seams - non-hazardous (or least dangerous) in terms of emissions of protective seams lying below or above the dangerous seam. [Ayruni A.T., Iofis M.A., Shmelev A.I. and others. The use of protective layers in coal mines. Overview. - M.: TSNIEIugol, 1981. - 34 p.].

The disadvantage of this method is the need for mine workings to open a coal seam, to develop a protective gas-bearing seam using special mining measures, which is associated with an increased risk of mining and high capital costs. In this case, the protective effect arises as a result of partial unloading of the massif adjacent to the developed formation from compressive stresses and changes in the initial gas state of the dangerous hazardous layers (gas pressure in the dangerous layer decreases, gas content of coal decreases, its gas permeability increases). Reliable protection takes place only in the zone with a sufficient level of unloading, ensuring a decrease in gas pressure (gas content of coal) in the formation to safe values

To reduce the intensity of methane release from coal seams into the mine workings of existing mines, preliminary degassing of unloaded coal seams before the start of treatment or preparatory work and current degassing of coal-bearing strata discharged from the rock pressure are used. In this case, degassing wells can be drilled from underground workings or from the earth's surface.

A known method of degassing and softening rocks, including drilling of formation wells and wells in the roof rock, their hydrotreating with liquid in static and hydro-pulse modes [RF Patent No. 2373398 for the invention "Method of degassing and softening of rocks", 04/15/2008].

The disadvantage of this method is that the suction of gas, which is in the array in an sorbed state, takes a long period of time, which causes a delay in the treatment.

There is a method of coal mining from hazardous formations, which consists in carrying out preparatory workings, drilling parallel wells from them into the formation, casing and sealing them, injecting fluids into the wells with pulsed pressure reliefs and releasing the destroyed coal, unloading and degassing the formation, followed by coal clearing. At the same time, water injection and impulse discharges are carried out, starting from the bottom of the well, the cleaning coal extraction begins after completion of the impact on the formation and the release of coal from the first two wells. When mining particularly hazardous seams before drilling wells from the preparatory mine into a coal seam, parallel boreholes are drilled to the depth of the zone of influence of the mine and inject solutions of coal in them [USSR Author's Certificate No. 1670129 A1, “Method for the extraction of coal from hazardous seams and a device for its implementation ", Publ. August 15, 1991].

However, this method is local in nature - degassing is carried out within the area of the developed reservoir. In addition, the drilling of degassing wells, the subsequent extraction of coal is carried out with the presence of people in the working face, which is unsafe under conditions of working out gas-saturated formations.

The closest in technical essence and the achieved result is the method of underground hydraulic mining of solid mineral deposits, which consists in opening the field with the help of wells, in hydraulic destruction by a pressure stream of water, disintegration and transfer of the destroyed mass into a hydraulic mixture in the bottom, transporting the hydraulic mixture from the bottom to the slurry well , raising the slurry to the surface, while before lifting the slurry to the surface, it is intensively mixed, its heavy PU is precipitated the empty part (waste rock) to the bottom of the cavity being washed, thus laying the mined-out space, the lightweight part of the hydraulic mixture consisting of pulp of minerals is sucked into the upper part of the cavity from which the hydraulic mixture (enriched water-carbon fuel) is lifted to the surface and transported directly through pipes to the consumer. [RF patent No. 2363849 for the invention "Method for the underground hydraulic development of solid mineral deposits", dated July 28, 2006, (prototype).]

The disadvantage of this method is the inability to control degassing processes in the development of mineral deposits, prone to explosions and sudden emissions of coal and gas. The method has limited application in the development of suites of gas-saturated formations, especially in the absence of a non-gas-saturated formation in the rock mass, which can be adopted as a protective one and practiced without special measures.

The aim of the invention is to increase the safety and efficiency of mining when developing suites of gas-bearing coal seams by degassing using a borehole method of coal mining.

This goal is achieved by using pre-unloading of coal seams and the enclosing rock mass as degassing by downhole extraction of coal from the seam, which is dangerous for gas emissions.

The invention is illustrated by drawings, where in FIG. 1 shows a diagram of the redistribution of rock pressure within the area of influence of a mine working along a protective formation; FIG. 2 shows a diagram of the location of wells on the earth's surface and protected areas.

The drawings show the wells - 1, the first practiced reservoir, which is used as a protective one - 2, the defenders of the overlying and underlying reservoirs - 3, the contour of the protected zone - 4, the space created by the wells in the reservoir accepted as protective - 5, protected areas overlying reservoir - 6, protected areas of the underlying reservoir - 7, the contour of the protected zone from the wells of the first stage - 8, the contour of the protected zone from the wells of the second stage - 9.

The essence of the method is as follows. When developing a suite of gas-saturated formations, a protective layer 5 is determined, the protective effect of which extends to the overlying and underlying layers. An opening is made using the wells 1. Then, a cavity 5 is created in the gas-saturated formation 2 using powerful physical effects (explosive, electro-hydraulic destruction, etc.).

To reduce the intensity of methane release from coal seams into the mine workings of existing mines, preliminary degassing and unloading of overlying and underlying coal seams before the start of treatment or preparatory work and the current degassing of coal-bearing strata unloaded from the rock pressure are used. In this case, degassing wells can be drilled from underground workings or from the earth's surface.

To further destroy the mineral as a powerful physical impact, we use our own natural energy - the high methane content of coal seams. Upon reaching the most explosive methane concentration of 10% in this cavity, an explosion is initiated, thereby destroying the mineral. The destroyed coal in the cavity is converted into a hydraulic mixture, intensively mixed, the waste rock is deposited on the bottom of the created cavity, then a water-coal suspension is fed to the surface using a hydraulic elevator.

In this case, the reference pressure in the rock mass adjacent to the worked-out space is reduced — sections 6, 7 (Fig. 1). The above-described method creates a mined-out space of such a size that the worked-out and worked-out coal seams 3 fall into the contour of the protected zone 4, in which the gas pressure in the seams decreases, the gas content of the coal decreases, and its gas permeability increases. Production wells are positioned so that the boundaries of the protective zones of the developed formation are evenly distributed over the protected formations. According to the recommended scheme for the development of coal deposits (Fig. 2), wells of the first stage 1 are drilled from the surface on a square grid, protected zones 8 are created as they are mined. The distance between the wells is taken based on the stability of the roof and the adopted recovery coefficient. After hydro production from four wells located in a square, wells of the second stage are drilled in the center of this square, while the protected zones of the second stage are created 9. At the same time, they ensure that the boundaries of the protective zones of the developed formation are located evenly along the protected layers.

Subsequently, these protective sections of coal seams 6, 7, which fall into the protected zone 4, are developed by traditional underground methods or by the above-described borehole methods.

This method allows for safe and efficient development of deposits prone to gas and geodynamic phenomena by preliminary degassing of coal seams using a downhole mining method, without the use of costly and not always effective local measures, which is especially important for large development depths and the use of modern high-performance technology, since the evolution of gas from the reservoirs is proportional to the volume of mining.

Claims (1)

The method of hydraulic coal mining from gas-saturated formations, which consists in opening the deposit with wells, destroying and transferring the mineral into a hydraulic mixture, mixing, sedimenting waste rock at the bottom of the formed cavity, pumping out the coal-water suspension to the surface and transporting it through pipes to the consumer, characterized in that it is preliminary degassing and unloading of overlying and underlying outburst coal seams and the host rock mass is carried out by downhole mining of coal from the seam and, hazardous in terms of coal emissions of rock and gas, taken as protective, while production wells are positioned so that the boundaries of the protective zones of the developed formation are evenly distributed over the protected formations.

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