SU756034A1 - Method of determining explosion hazard of coal seams - Google Patents

Description

The invention relates to the coal industry and can be used to determine the outburst of coal seams.

There is a method of predicting gas-dynamic phenomena on outburst coal seams, based on determining the amount of methane released into the well [1].

The disadvantage of this method is its relatively low reliability, since it does not take into account the connection of methane with coal and moisture.

There is a method of determining the outburst of coal seams, which consists in drilling a well, sampling coal from wells, determining the percentage of adsorbed water in coal samples by nuclear magnetic resonance, comparing the data with the reference [2].

The disadvantage of this method is the low accuracy of prediction.

The aim of the invention is to improve the accuracy of the forecast.

This goal is achieved by the fact that at the same time in samples of coal determine pro2

The cent content of adsorbed methane and in terms of the percentage of adsorbed methane in coal to the percentage of adsorbed water in coal determine the criterion for the gas-dynamic activity of the coal seam

5 _{K =} Doom

π Pe),

where G1 _M is the percentage of methane adsorbed in coal, weight. ° / ₀ ;

P _in - the percentage of adsorbed water in coal, weight. ° / ₀

10 moreover, for the values of the criterion of gas-dynamic activity, K = 0.003–0.008, the reservoir is referred to as non-hazardous in terms of gas-dynamic phenomena, and for the values of the criterion of gas-dynamic activity

К /> 0,025 for coal grade “Ж”, “К”, and “ОС ^

¹⁵ K> 0.015 for coal grade "T"

K> 0.01 for PA grade coal

the reservoir is classified as dangerous due to gas-dynamic phenomena.

2о Simultaneous determination of physically by nuclear magnetic resonance

associated with coal, i.e. adsorbed

in it methane and water allows you to set

at the molecular level their complex voz3

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action on the coal substance and evaluate

gas-dynamic activity of the reservoir.

The water adsorbed in the pores, besides having a plasticizing effect on coal, displaces free and some of the adsorbed methane, which has much smaller sorption bonds with coal than water. As a result, the energy of elastic deformations of a solid coal substance and the energy potential of methane are reduced. Therefore, the tendency of the reservoir to sudden outliers depends on the ratio of the percentage of adsorbed methane and water in the coal.

The method is implemented as follows.

Coal samples are taken from exploration (control) wells, which, with the current forecast, drill holes from the bottom of the lava or preparatory development deep into the reservoir. When drilling from the bottom of the lava wells are located at a distance of 10 m from each other, and in the bottom of the preparatory development of drilling two wells at a distance of 0.5 m from the wall of the excavation. Well depth 6—

8 m. Interval between coal sampling points along well length 2 m.

In the case of an advance prediction of the outburst risk of reservoirs over large areas of the well, drill holes from the haulage road ahead of the clearing face in the uprising of the reservoir to the entire height of the floor. Samples are taken at points with an interval of 5 m along the length of the well. Before each sampling, drilling is stopped and the well is cleaned of shtab. In inclined rising wells, cleaning occurs by gravity, and in horizontal wells - with the help of auger rods. Then, the well is drilled to a depth of 0.3-0.5 m and the destroyed coal coming from it is poured into a vessel, from where coal with a particle size of 5-6 mm is taken, placed into hermetically sealed glass test tubes and examined at the installation of nuclear magnetic resonance ( NMR). At each point at least three samples are taken. Sample studies at the NMR spectrometer are carried out without removing the coal from the tubes, which allows it to retain its natural water-methane saturation.

For comparative measurements, reference dry samples of coal are preliminarily prepared by evaporation at a temperature of 110 ° C and evacuation, a sample of coal is collected in a test tube, weighed on an analytical balance, and the spectrum is taken on an NMR unit. Then, in a chamber under pressure of 80-100 atmospheres, coal is alternately saturated with methane and water for 10 days, taken into test tubes, weighed on an analytical balance, and the spectrum is also taken on an NMR unit. The obtained spectrogram widths serve as a standard for the extraction of methane and water in the spectrograms of a water-methane mixture enclosed in a fossil coal.

The percentage of methane or water in coal is calculated from the ratio of the area contoured by the spectrogram of methane or water to the integral area, which also includes the area contoured by the structure spectrogram of coal.

The sewage hazard of a reservoir is determined by the ratio of the percentage of adsorbed methane (P _m ) to the percentage of adsorbed water in coal (P _c ). In case of detection of outbreaks of foci in a coal seam, prophylactic treatment is carried out, for example, by moistening and degassing under the action of moistening, for which use primary control wells, in which coal samples were taken for natural moisture. Then, between the primary Buryats, secondary test wells with coal sampling, the ratio of the percentage of adsorbed methane to the percentage of adsorbed water is determined, and the ratio at which the gasdynamic activity of the well is not shown as a criterion for a non-hazardous reservoir condition and excavation of coal seam lava.

Depending on the grade of coal, the values of Г1 _М and П _в may vary in a certain range. According to the degree of moisture adsorption, the grades of coal represented in non-hazardous formations are arranged in the following order: “PA” 2.5-3.0%, “T” 2-2.5%, “OS” 1.8-2.2 %, “F” and “K” 1.5-2.0%.

The out-of-safety prediction method was developed based on experimental studies on hazardous coal seam emissions: Lm— Removsky (Uglegorskaya mine), - Diamond (Stozhkovskaya mine), b - Nameless in Donbass. Conducted to determine the outburst of these coal seams. The test wells were drilled in the £ ₃ - Diamond formation from the stope to a depth of 8 m, and in the L ₃ formations - the Removskoye and - the Nezymyanny from the haulage drift after the rise of the reservoir to the entire height of the floor. The distance between the wells is 10 m, the interval between sampling points along the length of the wells is 2–5 m. Coal samples from the wells are immediately (within one to one and a half minutes) placed in glass hermetically sealed tubes, and then the spectrum is taken in a laboratory using an NMR spectrometer. The time of transportation of samples from the sampling site to the laboratory does not have a significant effect on the state of the coal samples that are in sealed vessels. ·

At the same time register the percentage

by weight, the content of adsorbed methane and water in the coal. For each point

6

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five

coal seam examines three samples. The relative deviation of the results in each sample from the average was no more than 0.07. The accuracy of determining the percentage of methane and water at each point is high. _five

The percentage of fluids at various points in hazardous and non-hazardous emissions zones changed at least two to three times. This reflected the heterogeneity of the reservoir structure in those and other zones. Emission hazard of the reservoir is poured by the manifestations of its gas-dynamic activity in certain zones during the drilling of wells.

It is established that when the ratio is> 0.025 for. Coal grades “Ж”, “K” and “OS”, 0 ^m > 0.015 for coal grade “T” ¹¹ and> 0.01 for coal grade “PA” the reservoir is dangerous due to sudden emissions, and when the ratio value is ^ <^ 0.003; ^^ 0.0015 and 0.008, respectively, for coal grades, the formation is not dangerous for emissions. The remaining 20 grades of coal are not contained in outburst formations.

Efficacy of prediction method is to improve the safety and productivity of workers working in formations prone to sudden vybro- ^2ί itself and coal gas. The method allows to increase labor productivity by 20% due to the cancellation of the blowout preventive measures at the seam sites that are not hazardous in terms of emissions.

Claims (1)

Claim The method of determining the outburst of coal seams, which consists in drilling wells, sampling coal from wells, determining the percentage of adsorbed water in coal samples by nuclear magnetic resonance, comparing the obtained data with the reference, characterized in that, in order to improve the accuracy of the forecast, simultaneously in the samples coal determine the percentage of adsorbed methane and the percentage of adsorbed methane in coal to the percentage of adsorbed water in coal the criterion of the gas-dynamic activity of the coal bed K = where P _m - the percentage of adsorbed water in coal (% by weight); P _in - the percentage of adsorbed water in coal (% wt.), moreover, when the criterion of hydrodynamic activity is set to k = 0.003–0.008, the reservoir is referred to as non-hazardous in terms of gas-dynamic phenomena, and for criterion values of gas-dynamic activity K> 0.025 for coal grade “Ж”, “К” _; and "OZZ", K> 0.015 for coal grade "T" K> 0.01 for coal grade "PA" layer referred to as dangerous for gas-dynamic phenomena.