RU2811143C1 - Method for determining mine methane resources at excavation site - Google Patents

Abstract

FIELD: mining; coal industry.

SUBSTANCE: method for determining mine methane resources at an excavation site includes measuring parameters of a coal rock mass, determining the methane content of coal seams, the flow rate of captured methane, air flow and methane content in it. Additionally, reserves and technological losses of coal in the excavation area of the mined seam are determined. The natural methane content of coal seams and, additionally, the degree of degassing of coal seams subject to unloading from rock pressure in the formation, both in the roof and in the soil of the developed seam, are determined by taking coal samples at the site using core gas samplers, followed by determining the methane content in the selected coal core. The angles of unloading of roof rocks and soil from the side sectional workings during mining of the developed seam are identified. Limit zones for unloading roof rocks and soil are determined by the intensity of methane release from adjacent coal seams into degassing wells. Methane resources at the excavation site are determined taking into account the coal reserves in the formation of the coal-bearing strata outlined by the discharge planes. The methane resources of the developed seam are determined by coal reserves and the difference between the natural methane content of the seam and the residual methane content of broken coal at the exit from the transport workings of the excavation site. The intensity of methane release in the workings during the destruction of coal by a combine and its background release from the exposed surfaces of the mined seam and mined-out space are measured. Coal mine methane resources are determined by the volume of its release in the workings and degassing networks of the site during the period of cleanup work on it. The background emission of methane is determined in the intervals between the next timing intervals of the combine operation based on the destruction of coal, readings from methane concentration and air flow sensors.

EFFECT: increasing the accuracy of determining coal mine methane resources.

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Description

The invention relates to mining, mainly to the coal industry, and can be used to determine realistic methane resources for extraction and utilization in coal mines within the existing mining section of the seam, mined by a longwall face.

There is a known method for forecasting coal mine methane resources in mining allotments of coal mines, including determining the methane content of coal seams in a coal-bearing formation, coal reserves in it, changes in the methane content of coal with depth from the zone of gas weathering of rocks, calculation of methane resources from coal reserves and methane content of coal seams [Problems of development methane-bearing layers in the Kuznetsk coal basin / Yu.N. Malyshev, Yu.L. Khudin and others - M.: Publishing house. Academy of Mining Sciences, 1997. - 463 p. (P. 125-129, 139-146)].

The disadvantage of this method is that methane resources are established for the entire mine field, although only part of them can be extracted in zones relieved from rock pressure during the development of a coal seam.

There is a known method for forecasting coal mine methane resources, including determining coal reserves in a formation and the methane content of coal with depth from the zone of gas weathering of rocks, establishing methane resources based on coal reserves and the methane content of coal seams [Geotechnological problems in the development of gas- and dust-hazardous coal seams / A.D. Ruban, G.S. Zaburdyaev, V.S. Zaburdyaev; Institute for Problems of Integrated Development of Subsoil of the Russian Academy of Sciences. - M.: Nauka, 2007. - 279 p. (pp. 244-247)].

The disadvantages of this method include the fact that it is impossible to extract the methane resources contained in coal-bearing formations within the mine field, since methane from coal seams and rocks is released mainly in excavation areas when they are unloaded from rock pressure.

The closest way to predict mine methane resources in terms of technical essence and the achieved result is a method that includes determining the methane content of coal seams in a coal-bearing formation, coal reserves in it, changes in the methane content of coal with depth from the zone of gas weathering of rocks, establishing the angles of unloading of roof rocks and soil during excavation of the developed seam, determination of methane resources based on coal reserves, methane content of coal seams and the dynamics of reduction in methane abundance (Assessment of resources and volumes of methane extraction during underground mining of coal deposits in Russia [A.D. Ruban, V.S. Zaburdyaev and G.S. Zaburdyaev. M .: Institute for Problems of Integrated Development of Subsoil of the Russian Academy of Sciences, 2005. - 152 pp. / pp. 6-14, 41-42, 230 (prototype)].

The disadvantage of this method is the low accuracy of determining methane resources at the excavation site due to the fact that methane resources are determined by multiplying coal reserves by the average methane content of coal in the formation.

The purpose of the invention is to increase the accuracy of determining mine methane resources due to reliable values of the natural and residual methane content of coal seams in the formation under the influence of their natural degassing during the process of cleaning work in the excavation area of the mine field, subject to unloading from rock pressure.

According to the invention, this goal is achieved by the fact that in the method of forecasting mine methane resources at an excavation site, which includes determining the parameters of the coal rock mass, the methane content of coal seams, the flow rate of captured methane, the air flow rate at the site and the methane content in it, the reserves and technological losses of coal at the excavation site are additionally determined area of the seam, measure the intensity of methane release into the workings during the destruction of coal by a combine and its background release from the exposed surfaces of the seam and goaf, methane resources are determined by the volume of its release into the workings and degassing networks of the site during mining operations on it, while the background release methane gas is installed in the intervals between the next timing intervals of the combine operation for the destruction of coal, readings of methane concentration and air flow sensors.

The method is carried out as follows.

In a section of a mine field, including a suite of coal seams above and below the seam being mined, the parameters of the coal rock mass, the methane content of the coal seams, the flow rate of captured methane, the air flow rate in the area and the methane content in it are determined. The natural methane content of coal seams is found experimentally or by dependence of its change with depth on the zone of gas weathering of coal-bearing rocks, or by direct determination in a mine. At the same time, according to the regulatory document, the angles of unloading of roof rocks and soil from the side sectional workings are established when mining the developed seam. The reserves and technological losses of coal at the mining site are determined. The reserves and technological losses of coal, the methane content of coal seams, the flow rate of captured methane, the air flow rate at the site and the methane content in it are determined by known (standard) methods, in accordance with current regulatory documents. Technological losses of coal consist of pillars left behind under shafts, rivers, railways, between mining areas, etc.

To determine the real resources of mine methane released within the mining area, in addition to the natural methane content of coal seams, the degree of degassing of coal seams subject to unloading from rock pressure in the suite, both in the roof and in the soil of the seam being mined, is additionally determined. This type of operation is performed instrumentally by taking coal samples at the site using core gas samplers, followed by determining the methane content in the selected coal core and recalculating it per ton of dry ash-free mass. Or they use a method based on the actual dependence of the degree of degassing of coal seams in a formation subject to unloading from rock pressure during the process of mining coal from the mined seam. This dependence includes the degree of degassing of the bottomhole zone from the developed coal seam, the limit zones and the degree of unloading of adjacent coal seams between the seams in the roof and soil of the developed seam during its mining at the excavation site.

The maximum discharge zones of roof rocks and soil are established experimentally, for example, by the intensity of methane release from adjacent coal layers into degassing or specially drilled wells.

Experimental work has established that during intensive mining of flat coal seams at a working face speed of 10-15 m/day on seams with a thickness of 3-3.5 m, the maximum unloading zones for roof rocks are 100-110 m, and for soils - 40-45 m. When excavating a coal seam with a thickness of 2-2.2 m, these zones are 100 m and 40 m, respectively. The unloading angles of roof rocks and soil within the excavation area are taken in accordance with the provisions of the “Instructions for degassing of coal mines” (2012), geological composition of the roof rocks and soil of the mined seam.

Methane resources at the excavation site are determined taking into account the coal reserves in the suite of coal-bearing strata outlined by the unloading planes by the product of coal reserves by the sum of the differences in the natural and residual methane content of the corresponding adjacent coal seams in the coal-bearing strata subject to unloading, and the methane resources of the developed seam - by coal reserves and the difference between the natural methane content of the formation and residual methane content of the broken coal at the exit from the transport workings of the excavation site.

The total methane resources in the excavation area of the mine field are summarized as the resources of the developed and adjacent coal seams and the gas-bearing rocks hosting the coal seams. At the same time, the dynamics of the decrease in the intensity of methane emission, which is established according to experimental data, is taken into account. The resources of free methane in rocks are taken in the amount of 10-15% of the methane resources of the developed coal seam within the excavation area, or cores are taken and then the content of free methane is determined in a ton of gas-bearing rocks and in the volume of collapsed rocks.

Measurement of air flow and methane content in it is carried out on the stream entering and leaving the longwall, and on the air flow emanating from the excavation area. At the same time, the intensity of methane emission is established at observation points for the gas state of the mine atmosphere at the mining site, and the volumes of coal production.

Within the mining allotment of a mine over the entire period of its operation, the total mine methane resources are composed of the resources of individual excavation areas for all mined seams in the coal-bearing suite.

The method makes it possible to increase the accuracy of determining the real mine methane resources at the excavation site and in general at the mining allotment of the mine for the entire period of its operation.

Claims (1)

A method for determining mine methane resources at an excavation site, including measuring the parameters of the coal rock mass, determining the methane content of coal seams, the flow rate of captured methane, air flow and methane content in it, characterized in that they additionally determine the reserves and technological losses of coal at the excavation site of the mined seam, determine natural methane content of coal seams and additionally the degree of degassing of coal seams subject to unloading from rock pressure in the formation both in the roof and in the soil of the developed seam by taking coal samples at the site using core gas samplers, followed by determining the methane content in the selected coal core, while establishing rock unloading angles roofs and soil from side sectional workings when mining the developed seam, the maximum unloading zones of roof and soil rocks are determined by the intensity of methane release from adjacent coal seams into degassing wells, methane resources at the excavation site are determined taking into account coal reserves in the suite of coal-bearing strata contoured by unloading planes, and methane resources of the developed seam - based on coal reserves and the difference between the natural methane content of the seam and the residual methane content of broken coal at the exit from the transport workings of the excavation site, measure the intensity of methane release in the workings during the destruction of coal by a combine and its background release from the exposed surfaces of the mined seam and mined-out space, Mine methane resources are determined by the volume of its release in the workings and the degassing networks of the site during the period of cleaning work on it, while the background release of methane is determined in the intervals between the next timing intervals of the combine operation for the destruction of coal, readings of methane concentration and air flow sensors.