SU1751357A1 - Method of assessing outburst hazard of coal seam - Google Patents

Abstract

The depth of pressing of the formation and the zone of the reference pressure are predetermined. The relative gassing from the wellbore space is measured. Drill holes to the depth of the reference pressure zone. Continuously and simultaneously with the measurement of the relative gassing from the wellbore space, the relative gassing of the hole in each hole of the reservoir is measured. With an increase in the depth of extraction of the reservoir, the relative gas release from the hole and the wellbore space in the subsequent dredging cycle, the reservoir is classified as non-hazardous. With constant extraction depth and relative gassing from the hole and an increase in the relative gassing from the bottom hole, the coal seam is considered outburst. 1 hp f-ly, 5 ill.

Description

The invention relates to mining and can be used in the development of coal seams that are prone to gas and coal emissions.

A known method for estimating the outburst hazard of a coal seam is based on determining its gas content, including interval drilling of holes, sealing their mouth, measuring the volume of released gas at each interval of the hole, and measuring the gas release from the hole walls, respectively, before and after drilling each hole interval.

The disadvantage of this method is relatively low reliability, since during the selection of a bone to determine

residual gas content in the laboratory method, a significant portion of the gas is lost.

The closest to the proposed technical essence and the achieved result is a method for estimating the emission efficiency of a coal seam, based on determining the gas content of the coal massif, including drilling control holes, measuring the volume of released gas and estimating gas content.

The disadvantage of this method is its low reliability, since by itself the level of gas emission can

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speak, since the control spur can cross a soufflter, an area of coal that is prone to intense extraction with increased gassing, etc. Therefore, a more reliable forecast should be based on an assessment of the gas content in general, incl. in the area of the excavation and in the depth of the array, covering the depth of plastic deformations.

The aim of the invention is to improve the reliability of the estimation of outburst coal seam.

The goal is achieved by the fact that in a known method, including drilling holes, sealing them, measuring the relative gas release from the hole, determining the gas content of the reservoir and estimating the outburst risk of this formation, preliminarily pressing the depth of the formation, determining the depth of the reference pressure zone, measure the relative gas emission from the bottom hole - the hole drilling is carried out to the depth of the reference pressure zone, while the relative gas release from the hole is measured continuously and simultaneously Rhenium of the relative gas release from the wellbore space in each cycle of the eMKVi reservoir and with an increase in the depth of the formation of the reservoir, the relative gas separation from the hole and the wellbore space in the subsequent cycle of the excavation, the layer is classified as non-hazardous, with constant spin depth and relative gas release the coal seam is considered outburst from the hole and the increase in the relative outgassing of gas from the wellbore space, and when the pressing depth and relative outflow of gas is reduced from the hole and into The growth of the relative gas emission from the bottomhole space of the coal seam is considered to be especially outburst. In order to ensure the safe location of the drift relative to the lava by establishing zones of increased and decreased gas-dynamic activity of the coal seam, the hole is drilled ahead of the hole and the distance at which the relative gas release from the hole takes an extreme value is determined.

Fig. 1 shows schematically the arrangement of the equipment necessary for carrying out the method; Fig. 2 is a graph showing the change in the relative gassing of the hole (curve 9) as measured by the movement of the clearing face; FIG. 3 is a graph showing the change in the relative gassing of the hole (curve 9) and the bottom hole (curve 10); FIG. 4 is a diagram of an air ejector for reducing

methane concentrations at the wellhead; figure 5 - view And figure 4.

The method is carried out as follows.

From the drift 1, drilling of the hole 3 in the formation 2 to a depth of 20-25 m is carried out. In the hole 3, a gas exhaust pipe 4, for example copper, 6-8 mm in diameter is installed and a gas chamber 5 is equipped

0 0.5-1.0 m long. The end of the tube 4 coming out of the hole 3 is perforated, i.e. along its perimeter, punch holes with a diameter of 0.05-2 mm. The holes are located 3-5 mm apart from each other. The length of the perforated end of the tube 4 is taken to be 10–15 cm. If necessary, reduce the length of the perforated part of the tube 4 and overlap it with a rubber tube with a diameter of 4–6 mm. Gazov

0 chamber 5 must be outside the zone of influence of the drift on the coal seam, i.e. not less than 10-12 m from the drift. Near the mouth of the hole 3, a settler 6 is equipped with a mixing chamber 7 mounted on measuring equipment 8, which uses a commercially available DMT-3 sensor, the latter transmits the measurement of the relative gas release from the hole to a stand with a recorder on the surface of the mine (curve 9) . Measurement data on the relative gas release ife in the wellbore space using the second DMT-3 sensor (curve 10) are also recorded on the same recorder. In the mixing chamber

5 7 there is a decrease in the background concentration of methane to about 0.5%, which is necessary for reliable operation of the DMT-3 sensor (the concentration of methane in the measuring chamber of the sensor should not exceed

0 2.5%.

Through tube 4, using the PG-2 MA instrument, the rate of gas release from hole 3 is measured. Immediately after sealing the hole, the rate of gas release 5 can be 2–5 l / min. After 0.5-1 h, the gas release rate decreases to 0.10-0.20 l / min or less and the tube 4 is connected to the apparatus 8. At the same time, the recorder on the surface of the mine records the curve 9 as it moves (Figure 2) which is conventionally divided into a series of segments characterizing a different state of the coal seam; bb is the area of compressed coal; b-in-transition section; in the f

5-part of that coal; е-с - zone of oriented cracks; e-f - zone untouched array. In this case, the zone of the onset of the deep-pressing in the near-bottom part of the coal seam, as a rule, is found according to curve 9 (Fig. 2) in its section c-d,

those. The spin depth is determined in this region.

With a high gas-bearing formation and a large gas release from the hole (more than 20–25 l / min), a more reliable source of reducing the background gas concentration values in the hole is necessary than the mixing chamber. To do this, instead of the mixing chamber 7, an ejector connected to the gas outlet tube 4 is installed at the mouth of the hole 3. A predetermined amount of compressed air is supplied to the ejector through a hose 11, which, coming out of the nozzle 12, expands the methane coming from the tube 4 to the discharge pipe 13 and from there the gas-air mixture of the desired concentration enters the measuring apparatus 8. Periodically, dust is removed from the ejector by removing the cover 14 in the sump 15. The downhole sealer 16 serves to install and fix the ejector to the hole of the hole 3.

The required amount of air is determined on the basis of providing the maximum gas concentration for which the sensor used is calculated. For example, for the AKM-DMT-3 sensor, the maximum gas concentration is 2.5%. Then the required amount of compressed air is determined from the expression:

P

100 Qr

OG + QB;

where Qr is the amount of methane released from the hole, l / min;

n is the maximum allowable concentration of methane in the mixture;

QB - the required amount of air, l / min.

From the expression (1) follows

QB Qr.

Received in Qr equal to 20 l / min and n 2.5%, from dependence (2) we obtain:

QB 0.78 m3 / min

The depth of the formation is determined by interval drilling of bore holes to the depth of the reference pressure zone and measuring the gas release rate. At the same time, the length of the spin (discharge) zone is determined by the dynamics of gas evolution. Then the coal is dredged. After each excavation cycle, the coal face approaches the location of the gas chamber 5 in the hole 3, while, as shown in Fig. 2, the methane concentration detected by the DMT-3 sensor from the hole increases from background to 1.5-2.0%

Borehole concentration of methane

space (FIG. 3, curve 10) increases from the background level to 1.0–1.5%. In both cases, maximum gas concentrations are recorded. Before excavation of the next cycle, the depth of the spin zone is again determined, and in the process of excavation, maximum concentrations of methane are recorded at the hole and in the wellbore space,

Using the graph of the relative gassing of the hole (curve 9)

5 and the wellbore space (curve 10) shown in FIG. estimation of coal bed outburst hazard If the pressing depth, relative gassing from the hole and the bottom hole increases in comparison with the previous cycle to the notches (K-0 and K -O segments), then the layer is classified as non-hazardous. At unchanged extraction depths (L-M section) and relative gas emission from a bore-hole and an increase in the relative gas release from the bottom-hole formation (segment / l-M), the coal seam is considered to be outwardly dangerous.

0 gassing from the bore-hole (segment М-Р) and an increase in the relative gassing from the bottomhole space (segment М-Р) the layer is considered to be particularly outburst.

5 To ensure the safe location of the drift relative to the lava, the gas concentration is measured near the hole 3, which is located on the border of the reference pressure zone or outside it. By

As the bottom of the gas chamber 5 of the hole 3 approaches, the change in the concentration of methane (figure 2) is recorded in comparison with the background, that is, more than 0.5%.

The distance from the foot is determined

5 where the maximum concentrations of methane are recorded. At this distance ahead of the intake pressure, the downward pressure is most active, therefore, the bottom of the haulage drift ahead of the face is located at a distance greater or less than the specified distance. For example, if the distance at which the maximum concentration of methane is recorded is 15 m, then the bottom hole

5 roadways are located more or less than 15 m.

Claims (2)

Claim 1. A method for estimating the outburst hazard of a coal seam, including drilling holes, sealing them, measuring the relative gas release from a hole, determining the gas content of the reservoir, and estimating the hazard of this reservoir, is characterized by the fact that, in order to improve the reliability of the outburst assessment of the coal seam, pre-pressing the depth of the reservoir, the depth of the reference pressure zone, measure the relative gassing from the bottomhole space, drilling holes are made to the depth of the reference zone The measurements of the relative gassing of the hole are carried out continuously and simultaneously with the measurement of the relative gassing of the reservoir in each cycle of excavation and with increasing depth of extraction of the reservoir, the relative gas release of the hole and the bottom hole in the subsequent cycle of excavation of the reservoir to a non-flaking one, with constant extraction depth and relative gas release from the hole and an increase in the relative gas release from the wellbore space, the coal seam is considered outburst-hazardous, and when reducing the depth of the spin and the relative gas release from the hole and an increase in the relative gas release from the wellbore space, the coal layer is considered to be a particular emission hazard. 2. The method according to claim 1, characterized in that, in order to ensure the safe location of the drift relative to the lava by establishing zones of increased and decreased gas-dynamic activity of the coal seam, the hole is drilled ahead of the bottom and the distance at which the relative gassing from the hole is determined takes extreme value. , (sn; h) eight J, M Phys.