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1、精選優(yōu)質(zhì)文檔-傾情為你奉上Control and prevention of gas outburstsMaría B. Díaz Aguado C. González （International Journal of Coal Geology 69(2007)253-266）Abstract： Underground coal mines have always had to control the presence of different gases in the mining environment. Among these gases, methane

2、 is the most important one, since it is inherent to coal. Despite of the technical developments in recent decades, methane hazards have not yet been fully avoided. This is partly due to the increasing depths of modern mines, where methane emissions are higher, and also to other mining related circum

3、stances, such as the increase in production rates and its consequences: difficulties in controlling the increasing methane levels, increasing mechanization, the use of explosives and not paying close attention to methane control systems. The main purposes of this paper are to establish site measurem

4、ents using some critical parameters that are not part of the standard mining control methods for risk assessment and to analyze the gas behavior of subvertical coal seams in deep mines in order to prevent gas incidents from occurring. The ultimate goal is the improvement in mining conditions and the

5、refore in safety conditions.Key words： Coal mines，coal-seam methane，gas pressure，permeability，gas outburst- potential. 專心-專注-專業(yè)一.Introduction Coalbed and coal mine methane research is thriving due to the fact that power generation from coal mine methane will continue to be a growing industry over th

6、e coming years in certain countries. For instance, China, where 790 Mm3 of CH4 were drained off in 1999 (Huang, 2000), has 30 Tm3 of estimated CBM potential in the developed mining areas (Zhu, 2000). The estimate by Tyler et al. (1992) of the inplace gas in the United States is about 19 Tm3, while G

7、ermany's total estimated coalbed methane resources are 3 Tm3, very similar to Polish or English resources (World Coal Institute, 1998). This increase in the CBM commerce has opened up new lines of research and has allowed the scientific community to increase its knowledge of some of the properti

8、esof coal and of methane gas, above all with respect to the properties that determine gas flow, which until now had not been sufficiently analyzed. Some of these parameters are the same ones that affect the occurrence of coal mining hazards, as methane has the potential to become a source of differe

9、nt fatal or nonfatal disastrous events. 二.Description of the Asturian Central basin and of the 8thCoalbed The 8th Coalbed of the RiosaOlloniego unit, located in the Southwest of the Asturian Central Coal Basin (the largest coal basin in the Cantabrian Mountains, IGME, 1985), has CBM potential of abo

10、ut 4.81 Gm3. This is around 19.8% of the estimated resources of the Asturian Central Basin and 12.8 % of the total assessed CBM resources in Spain (Zapatero et al., 2004). 3.84 Gm3 of the CBM potential of the 8th Coal-bed belongs to San Nicolás and Montsacro: 1.08 Gm3 to San Nicolás area a

11、nd 2.76Gm3 to Riosa, down to the 800m level (IGME, 2002). The minable coalbeds of this unit are concentrated in Westphalian continental sediments (Suárez-Ruiz and Jiménez, 2004). The RiosaOlloniego geological unit consists of three seams series: Esperanza, with a total thickness of 350 m,

12、contains 36 coalbeds with a cumulative coal thickness of 3.5 to 6.5 m; Pudingas, which is 700 m thick, has 35 coalbeds with a thickness of 57m; whereas the Canales series, the most important one, I 800 m thick, with 812 coalbeds that sum up to 1215 m thick. This series, which contains the 8th Coalbe

13、d, the coal-bed of interest in this study, has a total thickness of 10.26mat SanNicolás and 15.13matMontsacro (Pendás et al., 2004). Fig. 1 shows the geological map of the two coal mines, whereas Fig. 2represents a front view of both mines and the location of the instrumented areas. In thi

14、s particular study, the 8th Coalbed is situated at a depth of between 993 and 1017 m, in an area of low seismi intensity. Instantaneous outbursts pose a hazard to safe, productive extraction of coal in both mines. The mechanisms of gas outbursts are still unresolved but include the effect of stress,

15、 gas content and properties of the coal. Other factors such as geological features, mining methods, bord and pillar workings or increase in rate of advance may combine to exacerbate the problem (Beamish and Crosdale, 1998). Some of the main properties of the 8th Coalbed favoring gas outbursts (Creed

16、y and Garner, 2001; Díaz Aguado, 2004) had been previously studied by the mining company, in their internal reports M.B. Díaz Aguado, C. González Nicieza / International Journal of Coal Geology 69(2007)253 Fig. 1. Geological map.As well as in the different research studies cited in Se

17、ction The geological structure of the basin, the stress state of the coal-bed and its surrounding wall rock and some properties of both coal-bearing strata and the coalbed itself. The next paragraphs summarize the state of the research when this project started. Many researchers have studied relatio

18、nships between coal outbursts and geological factors. Cao et al. (2001), found that, in the four mining districts analyzed, outbursts occurred within tectonically altered zones surrounding reverse faults; this could help to delimit outburstprone zones. In the 8th Coalbed, some minor outbursts in the

19、 past could be related to faults or changes in coal seam thickness. Hence, general geological inspections are carried out systematically, as well as daily monitoring of any possible anomalies. But, in any case, some other outbursts could be related neither to local nor general faults. Fig. 2. Genera

20、l location of the study area. M.B. Díaz Aguado, C. González Nicieza / International Journal of Coal Geology 69 (2007) 253266 For some years now, the technical experts in charge of the mine have been studying the stress state of the coalbed by means of theoretical calculations of face end o

21、r residual rock mass projections that indicated potential risk areas, based on Russian standards (Safety Regulations for Coal and Oil Shale Miners, 1973).Assuming that there was an initial approach to the stress state, this parameter was therefore not included in the research study presented in this

22、 paper. In the Central Asturian Coal Basin, both the porosity and permeability of the coal-bearing strata are very low,the cleat structure is poorly developed and cleats are usually water-filled or even mineralized. Consequently, of 5.10 m3/t. In some countries, such as Australia (Beamish and Crosda

23、le, 1998) or Germany, a gas outburst risk value has been established when methane concentration exceeds 9 m3/t (although close to areas of overpressure, this risk value descends to 5.5 m3/t). As the average gas contents in the coalbed are comparable with those of the Ruhr Basin (which according to F

24、reudenberg et al., 1996, vary from 0 to 15 m3/t), the values in the 8th Coalbed would be close to the risk values. Desorption rate was considered the most important parameter by Williams and Weissmann (1995), in conjunction with the gas pressure gradient ahead of the face. Gas desorption rate (V1) h

25、as been defined as the volume of methane, expressed in cm3, that is desorbed from a 10 g coal sample, with a grain size between 0.5 and 0.8 mm, during a period of time of 35 s (fromsecond 35 to 70 of the test). Desorption rates have been calculated from samples taken at 2 m, 3 m and 7 m, following t

26、he proceedings of the Technical Specification 0307-2-92 of the Spanish Ministry of Industry. The average values obtained during the research are: 0.3 cm3 / (10 g·35 s) at 2 m depth, 0.5 cm3 / (10 g·35 s) at 3 m and 1.6 cm3 / (10 g·35 s) at the only paths for methane flow are open frac

27、tures. Coal gas content is one of the main parameters that had been previously analyzed. The methane concentration in the Central Asturian Basin varies between 4 and 14 m3/t of coal (Suárez Fernández, 1998). Particularly, in the RiosaOlloniego unit, the gas content varies from 3.79 to 9.89

28、 m3/t of coal (Pendás et al., 2004). During the research, the measured values in the area of study have varied between 4.95 and 8.10 m3/t, with an average value7m.Maximumvalues were of 1.7 cm3 / (10 g·35 s) at 2m depth, 3.3 at 3 m and up to 4.3 cm3 / (10 g·35 s) at 7 m.The initial cri

29、tical safety value to avoid gas outbursts in the 8th Coalbed was 2 cm3 / (10 g·35 s). Due to incidents detected during this research study, the limit value was reduced to 1.5 cm3 / (10 g·35 s). But other properties, such as coal gas pressure, the structure of the coal itself and permeabili

30、ty, had beeninsufficiently characterized in the Riosa Olloniego unit before this research study. Two methods had been previously employed to determine the gas pressure in the mine: the Russian theoretical calculations for the analysis of the stress state and the indirect measurements of the gas pres

31、sure obtained by applying criteria developed for the coalbeds of the Ruhr Basin (Germany), Poland and the former Soviet Union. These indirect measurements were the Jahns or borehole fines test (Braüner, 1994), which establishes a potential hazard when the fines exceed a limiting value. Although

32、 there are tabulated values for the coalbeds of the Ruhr Basin, it is not the case for the coals of the RiosaOlloniego unit. Therefore, in this paper an improvement to the gas pressure measurement technique is proposed by developing a method and a device capable of directly measuring in situ pressur

33、es. The 8th Coalbed is a friable bituminous coal, high in vitrinite content, locally transformed into foliated fabrics which, when subjected to abutment pressure, block methane migration into working faces (Alpern, 1970). With low volatile content, it was formed during the later stages of coalificat

34、ion and, as stated by Flores (1998) this corresponds to a large amount of methane generated. Moreover, the coal is subject to sudden variations in thickness (that result in unpredictable mining conditions) and to bed-parallel shearing within the coalbed, that has been considered an influence on gas

35、outbursts (Li, 2001). Its permeability had never been quantified before in this mining area. Thus, during research in the 8th Coalbed it was decided to perform in situ tests to measure pressure transients, to obtain site values that will allow future calculations of site permeability, in order to ve

36、rify if it is less than 5 mD, limit value which, after Lama and Bodziony (1998), makes a coalbed liable to outbursts. Therefore, in this study we attempted to characterize gas pressure and pressure transients, for their importance in the occurrence of gas outbursts or events in which a violent coal

37、outburst occurs due to the sudden release of energy, accompanied by the release of significant amount of gas (González Nicieza et al.,2001), either in breaking or in development of the coalbed (Hardgraves, 1983). 三.Conclusions Coalbed is still a major hazard affecting safety andproductivity in

38、some underground coal mines. This paper highlights the propensity of the 8th Coalbed to give rise to gas outbursts, due to fulfilling a series of risk factors, that have been quantified for 8th Coalbed for the first time and that are very related to mining hazards: gas pressure and its variation, wi

39、th high valuesmeasured in the coalbed, obtaining lower registers at Montsacro than at San Nicolás (where 480 kPa were reached in the gas pressure measurements at the greatest depth). These parameters, together with the systematic measurement of concentration and desorption rate that were alread

40、y being carried out by the mine staff, require monitoring and control. A gas-measurement-tube set was designed, for measuring gas pressure and its variations as well as the influence of nearby workings to determine outburstprone areas. The efficacy of injection as a preventative measure was shown by

41、 means of these measurement tubes. References1 Alexeev, D.M., 2004. 2 True triaxial loading apparatus and its application to coal outburst prediction. Int. J. Coal Geol. 58, 245250. 3 Alpern, B., 1970. Tectonics and gas deposit in coalfields: a bibliographical study and examples of application. Int.

42、 J. Rock Mech. Min. Sci. 7, 6776. 4 Beamish, B.B., Crosdale, J.P., 1998. Instantaneous outbursts in underground coal mines: an overview and association with coal type. Int. J. Coal Geol. 35, 2755. 5 Braüner, G., 1994. Rockbursts in Coal Mines and Their Prevention. Balkema, Rotterdam, Netherland

43、s. 137 pp. 6 Cao, Y., He, D., Glick, D.C., 2001. Coal and gas outbursts in footwalls of reverse faults. Int. J. Coal Geol. 48, 4763. 7 Durucan, S., Edwards, J.S., 1986. The effects of stress and fracturing on permeability of coal Min. Sci. Technol. 3, 205216. 8 Flores, R.M., 1998. Coalbed methane: f

44、rom hazard to resource. Int. J. Coal Geol. 35, 326.瓦斯治理和預(yù)防M.B.迪亞斯·阿瓜多、爾岡薩雷斯·尼茨迊（煤炭地質(zhì)69（2007）253-266國際雜志）摘要：在煤礦井下開采環(huán)境中必須控制著不同氣體的存在。在這些氣體中，甲烷是最重要的一個(gè)，它伴隨著煤而產(chǎn)生。雖然有幾十年內(nèi)科技的發(fā)展，但瓦斯災(zāi)害未能完全避免。這種情況部分由于現(xiàn)代礦井開采深度的增加，甲烷排放量增高；也和其他開采相關(guān)情況有關(guān)，如生產(chǎn)率的提高和它的后果：在控制日益增加的甲烷含量方面有很多困難，日益增加的機(jī)械化，爆炸品的使用，不太關(guān)注瓦斯控制系統(tǒng)。本文的主要目的是

45、使用一些不屬于用于風(fēng)險(xiǎn)評(píng)估的標(biāo)準(zhǔn)采礦控制方法的一些關(guān)鍵參數(shù)，建立現(xiàn)場測(cè)量，并分析直立煤層深部煤礦瓦斯行為，以防止偶然發(fā)生瓦斯事故。最終目標(biāo)是開采條件的改善，安全條件的提高。關(guān)鍵詞：煤礦，煤層氣，氣體壓力，滲透率，瓦斯突出。一.簡介由于某些國家在未來幾年內(nèi)，煤礦瓦斯氣發(fā)電將會(huì)是一個(gè)繼續(xù)增長的工業(yè)，因此煤層和煤礦瓦斯研究得到蓬勃發(fā)展。例如，中國，其中在1999年（黃，2000）有790 Mm3的甲烷涌出，估計(jì)發(fā)達(dá)礦區(qū)煤層氣潛力為30 Tm3（朱，2000）。由泰勒等人（1992）的估計(jì)，在美國地區(qū)天然氣約為19 Tm3，而德國的煤層氣資源總量估計(jì)有3 Tm3，與波蘭文或英文資源非常相似（世界煤炭研

46、究所，1998年）。煤層氣商業(yè)的增加開辟了研究的新領(lǐng)域，也使科學(xué)界增加對(duì)煤炭和甲烷氣體的知識(shí)，尤其是關(guān)于決定氣體流動(dòng)的屬性，直到現(xiàn)在還沒有得到充分的分析。其中一些參數(shù)影響了煤炭開采危害的發(fā)生，甲烷有可能成為一個(gè)不同的致命或非致命的災(zāi)難性事件的源頭。二.阿斯圖里亞斯中央盆地第8煤層氣的描述RiosaOlloniego單位的第8煤層，坐落于阿斯圖里亞斯中央煤盆地西南（在坎塔布連山脈，IGME，1985年最大的煤盆地），具有潛在煤層氣約4.81 Gm3。這是大約19.8的阿斯圖里亞斯中部盆地的資源估計(jì)數(shù)和西班牙煤層氣資源總估值的12.8（薩帕特羅等，2004）。第8煤層潛在煤層氣的3.84 Gm3屬

47、于圣尼古拉斯和蒙托薩克：圣尼古拉斯的1.08 Gm3和利薩的2.76 Gm3，降至水平800米以下（IGME，2002）。 該區(qū)煤層主要集中在威斯特伐利亞（蘇亞雷斯- 瑞茲和希門尼斯，2004年）的陸相沉積中。Riosa- Olloniego地質(zhì)單元的三種些列的煤層組成：總厚度為350 m的埃斯佩朗莎，包含3-6個(gè)為3.5-6.5 m厚煤層的煤床; 總厚度700 m的布丁伽斯，包含3-5個(gè)5-7 m厚煤層的煤層；而卡納萊斯系列，最重要的一個(gè)，有8-12個(gè)煤層，總厚度800 m，累計(jì)厚度12-15 m。這個(gè)系列，其中包含第8煤層，是這個(gè)研究中的利益所在，擁有總厚度達(dá)10.26 mat的圣尼古拉斯

48、和15.13 mat的蒙托薩克（Pendás等，2004）。圖1顯示了兩個(gè)煤礦地質(zhì)圖，而圖2顯示兩個(gè)礦井正視圖和儀器的位置。在這項(xiàng)特殊的研究中，第8煤層氣位于深度993和1017 m之間，一個(gè)低的地震強(qiáng)度區(qū)域。在這兩個(gè)煤礦的煤炭生產(chǎn)中，瞬時(shí)爆發(fā)對(duì)安全造成危害。瓦斯爆炸的機(jī)制仍然沒有得到解決，但包括壓力，瓦斯含量和煤的性質(zhì)的影響。其他因素，如地質(zhì)特征，開采方法，巷道和支柱的運(yùn)作，推進(jìn)增加速率可使問題進(jìn)一步惡化（比米什和克洛斯戴勒，1998年）。易于煤層瓦斯突出（科瑞迪與加納，2001年，迪亞斯·阿瓜多，2004年）的第8煤層的一些主要屬性以前曾由礦業(yè)公司研究，出現(xiàn)在其內(nèi)部報(bào)告

49、。M.B.迪亞斯·阿瓜多、爾岡薩雷斯·尼茨迊/煤炭地質(zhì)69（2007）253-266國際雜志圖1 地質(zhì)圖以及在不同的研究報(bào)告中引用部分盆地地質(zhì)結(jié)構(gòu)，煤層壓力狀態(tài)及周邊圍巖，還有含煤層及煤層本身兩者的一些屬性。接下來的段落總結(jié)了本研究項(xiàng)目開始時(shí)的狀態(tài)。許多研究人員研究瓦斯爆炸與地質(zhì)因素的關(guān)系。曹等（2001年）發(fā)現(xiàn)，在四個(gè)礦區(qū)進(jìn)行了分析，爆炸發(fā)生在周圍是逆斷層蝕變構(gòu)造區(qū)；這將有助于劃定爆炸易發(fā)區(qū)。在第8煤層，過去的一些輕微的爆炸可能與斷層或煤層厚度變化聯(lián)系在一起。因此，進(jìn)行常規(guī)系統(tǒng)地地址檢查，以及日常監(jiān)測(cè)任何可能出現(xiàn)的異常情況。但是，無論如何，總有一些其他的爆炸可能既與當(dāng)?shù)匾?/p>

50、與一般斷層無關(guān)。圖2 常規(guī)位置的研究區(qū)域。 M.B.迪亞斯·阿瓜多、爾岡薩雷斯·尼茨迊/煤炭地質(zhì)69（2007）253-266國際雜志一些年來，依據(jù)俄羅斯標(biāo)準(zhǔn)（安全煤和油頁巖的礦工，1973年規(guī)例），負(fù)責(zé)煤礦的技術(shù)專家已研究了煤層壓力狀態(tài)下通過能夠揭示潛在危險(xiǎn)區(qū)域的工作面的理論計(jì)算端頭或殘留巖體的預(yù)測(cè)，指出潛在的危險(xiǎn)地區(qū)。假設(shè)有一個(gè)初步的辦法來應(yīng)對(duì)壓力狀態(tài)，這個(gè)參數(shù)因此沒有包括在這個(gè)研究性學(xué)習(xí)的文件中。在阿斯圖里亞斯煤中央盆地，無論是孔隙度還是含煤層的滲透率都非常低，夾板結(jié)構(gòu)不發(fā)達(dá)，夾板通常充滿水，甚至礦化。因此， 5.10 m3/t。在一些國家，諸如澳大利亞（比米什和克洛

51、斯戴勒，1998年）或德國，一個(gè)瓦斯爆炸的風(fēng)險(xiǎn)值已建立，當(dāng)甲烷濃度超過9 m3/t（盡管接近超壓區(qū)，此風(fēng)險(xiǎn)值下降到5.5 m3/t）。由于平均煤層瓦斯含量平均與那些魯爾盆地（根據(jù)科德寶集團(tuán)等。1996年，從0變化到15 m3/t）相當(dāng)，在第8煤層值將接近的風(fēng)險(xiǎn)值。 脫附速率和工作面前方瓦斯壓力梯度被威廉姆斯和韋斯曼（1995年）認(rèn)為是最重要的參數(shù)。瓦斯解吸率（V1）被定義為，在35 s時(shí)間內(nèi)，由10 g晶粒尺寸在0.5和0.8 mm之間煤的樣解吸得到甲烷立方厘米體積量。解吸率計(jì)算，從2 m，3 m和7 m處得到樣本，遵循西班牙工業(yè)部技術(shù)規(guī)范0307-2-92。研究中得到的平均值是：在2 m的深度0.3 cm3/（10 g·35 s），在3 m的深度0.5 cm3/（10 g·35 s）和在甲烷流動(dòng)唯一路徑開放斷裂情