低透气性近距离强突出煤层群瓦斯治理模式研究

低透气性近距离强突出煤层群首采层打钻极易喷孔,引发瓦斯安全事故。以皖北煤电祁东煤矿II三采区为例,基于首采层7₁煤分段压裂水平井预抽煤层瓦斯改性效果和上区段8₂煤定向长钻孔拦截抽采下临近层9煤卸压瓦斯效果,提出了综合运用分段压裂水平井、定向长钻孔、地面钻井、多用底板巷、顶板走向钻孔等技术的瓦斯治理模式,可有效减少井下工程量,提高钻孔施工及抽采效率,保证煤层安全高效开采。该模式演变后可进一步减少巷道和钻孔工作量,有效缓解接替紧张压力。     

新庄孜矿B8保护层开采对B6煤效果考察实践分析

以突出矿井新庄孜矿为例,介绍了煤层群开采首采保护层卸压瓦斯抽采工程设计及被保护层瓦斯抽采效果。通过在66208工作面回采过程中瓦斯压力测定、瓦斯抽采效果和煤层最大变形量的考察,得出保护层工作面开采后,被保护层B_6煤层透气性系数增大了902倍,B_6煤层残余瓦斯含量为2.43 m~3/t;得出实际走向及倾向方向上的有效保护范围。最大化的回收煤炭资源,取得了较好的效果。     

近距离煤层群首采保护层工作面瓦斯综合治理技术研究

瓦斯治理仍是世界性难题。本文针对赤峪煤矿近距离高瓦斯煤层群首采保护层C0202工作面瓦斯治理问题,提出了沿空留巷Y型通风配合本煤层顺层钻孔、两巷底板穿层钻孔、顶抽巷高位穿层钻孔、采空区埋管的＂五措并举＂治理措施,实现了工作面成功连续留巷200m,瓦斯抽采率高达70%,回风流瓦斯浓度控制在0.4%左右的效果,保证了工作面的安全高效开采。该研究成果可为赋存条件相似的煤层群开采瓦斯治理提供借鉴。     

煤与远程卸压瓦斯安全高效共采试验研究

运用高瓦斯煤层群煤与瓦斯安全高效共采的思想,在淮南潘一矿进行了煤与瓦斯安全高效共采及远程瓦斯抽采的试验研究：首先开采瓦斯含量低、无突出危险的B11煤层,利用其采动影响使处在其上部70m(相对层间距35)的C13煤层卸压,煤层透气性系数增加近3000倍,瓦斯大量解吸并形成了沿顺层张裂隙流动的条件,通过在C13煤层底板沿走向布置的瓦斯抽采巷向C13煤层均匀地打网格式上向穿层钻孔,C13煤层内的卸压解吸瓦斯在煤层残余瓦斯压力和抽采负压作用下沿顺层张裂隙向抽采钻孔汇集,瓦斯抽采率达60%以上,不仅消除了煤与瓦斯突出危险性,而且相对瓦斯涌出量由原来25m^3／t下降到5m^3／t,工作面日产量由原来的1700t提高到5100t,成功地实现了煤与瓦斯两种资源的安全高效共采。     

突出矿井煤层群开采首采保护层区域消突技术实践

以突出矿井谢桥煤矿为例,介绍了煤层群开采首采保护层卸压瓦斯抽采工程设计和被保护煤层卸压瓦斯抽采效果.实践表明,谢桥矿1242(1)保护层开采实践证明,在11-2煤层有效保护范围内的13-1煤层,可充分消除其突出危险性,并有利于被保护层瓦斯治理;经保护层开采后,不仅能最大程度消除高瓦斯突出危险煤层的瓦斯事故隐患,而且极大地提高了巷道掘进速度,从而缓解了工作面接替的紧张局面,有效提高了生产效率.保护层开采区域消突技术是防治煤与瓦斯突出最经济、有效的技术措施.     

深井煤层群首采下保护层工作面瓦斯治理技术

本文以千米深井——朱集煤矿1242(1)首采工作面的瓦斯治理为例,提出并实施了地面钻井、高抽巷和采空区埋管相结合的瓦斯分源治理综合技术,分别抽采上覆13-1煤层卸压瓦斯、顶板瓦斯富集区瓦斯和上隅角瓦斯。实践表明,1242(1)工作面平均绝对瓦斯涌出量为68.8m3/min,地面钻井平均瓦斯抽采量为28.7m3/min,占瓦斯涌出量的42.2%,高抽巷平均瓦斯抽采量为30.7m3/min,占瓦斯涌出量的45.2%,瓦斯抽采率高达87.4%,回风流瓦斯浓度低于0.4%,实现深井高瓦斯煤层群首采下保护层工作面的安全高效开采。研究成果对类似条件矿井首采层工作面的瓦斯治理有指导价值。     

突出矿井深部新水平开采瓦斯综合治理模式研究

针对矿井浅部瓦斯治理模式已不能保障深部采区安全高效生产的现状,提出一种适宜矿井深部新水平开采的瓦斯综合治理模式.工作面消突采用底板岩巷穿层钻孔预抽煤巷条带瓦斯;底板岩巷布置“一巷多用”,在工作面回采工程中可兼做回风巷、尾抽巷、措施巷;回采工作面采用沿空留巷Y型通风综合治理瓦斯.其中,顺层钻孔预抽本煤层瓦斯,高位钻场顶板走向钻孔抽采裂隙带瓦斯,上隅角、尾巷埋管抽采采空区瓦斯,形成矿井三维立体瓦斯抽采体系.     

近距离突出煤层群瓦斯治理技术优化的研究

近距离突出煤层群工作面受上下邻近煤层卸压瓦斯的影响,致使回采工作面瓦斯涌出量大、工作面回风隅角及回风巷中的甲烷传感器频繁报警,瓦斯治理消耗大量的人力、物力和时间,严重制约了矿井的安全生产。通过对几种瓦斯治理方案进行分析论证,得出将整个煤层群作为一个治理单元,统筹考虑,将煤层厚度、瓦斯含量相对较小的弱突出煤层作为关键保护层,配合打钻进行立体式抽采,实现上下递进保护,最大限度地抽采邻近煤层的卸压瓦斯的方案。现场实践结果表明,保护层工作面在回采期间瓦斯抽采率高达90%以上,回风隅角瓦斯浓度降至0.6%以下,回风巷风流中瓦斯浓度降至0.2%以下,工作面月平均回采长度由原来的120 m提高至200 m。同时,从根本上解决了被保护层工作面回采期间瓦斯带来的安全威胁。     

煤层群下保护层开采卸压范围扩界研究

通过开采保护层降低高突出煤层的危险性,作为一种有效的保护措施,在煤矿开采中得到广泛应用。而准确探究近距离煤层下保护层卸压范围,对合理布置保护层,提高卸压效率显得尤为重要。在过去,我们一般认为倾向卸压角度为80°左右,沿走向的保护范围卸压角在56°～60°左右。本文在前人研究的基础上,通过数值模拟及现场考察等方法,获得了近水平上被保护层工作面走向上和倾向上的煤层膨胀变形规律,在下保护层的设计中,为相对原来规定的范围增加扩界区域提供一定的理论支持。走向上通过对其卸压瓦斯的抽采,扩界区域同样可处于有效保护范围内,即走向卸压角可由56°提高至90°左右。倾向上可考虑将卸压角度由80°增大为90°,实现保护层与被保护层的等宽布置。并以淮南朱集矿1111(1)工作面首采保护层的现场监测数据做对照,分析结果与实际值相符。     

高瓦斯煤层群保护层开采卸压效果数值模拟

为合理选择保护层,针对高瓦斯突出煤层群安全开采问题,分析了保护层开采的保护作用机理,即保护层开采可对被保护层起到卸压增透作用,改善被保护层的瓦斯抽放效果是解决煤与瓦斯突出问题及瓦斯灾害的重要技术手段;卸压对煤与瓦斯突出及瓦斯问题的解决具有决定作用.针对某矿高瓦斯突出煤层群生产地质条件,采用FLAC3D数值软件模拟2个非突出煤层作为保护层开采时的卸压效果,并对其进行了分析比较,研究结果可为保护层的合理选择提供参考依据.     

Pressure relief, gas drainage and deformation effects on an overlying coal seam induced by drilling an extra-thin protective coal seam

Numerical simulations and field tests were used to investigate the changes in ground stress and deformation of, and gas flow from, a protected coal seam under which an extra-thin coal seam was drilled. The geological conditions were: 0.5 meter min-ing height, 18.5 meter coal seam spacing and a hard limestone/fine sandstone inter-stratum. For these conditions we conclude: 1) the overlying coal-rock mass bends and sinks without the appearance of a caving zone, and 2) the protected coal seam is in the bending zone and undergoes expansion deformation in the stress-relaxed area. The deformation was 12 mm and the relative defor-mation was 0.15%. As mining proceeds, deformation in the protected layer begins as compression, then becomes a rapid expansion and, finally, reaches a stable value. A large number of bed separation crannies are created in the stress-relaxed area and the perme-ability coefficient of the coal seam was increased 403 fold. Grid penetration boreholes were evenly drilled toward the protected coal seam to affect pressure relief and gas drainage. This made the gas pressure decrease from 0.75 to 0.15 Mpa, the gas content de-crease from 13 to 4.66 m3/t and the gas drainage reach 64%.     

朱仙庄煤矿Ⅱ831工作面区域条带消突技术研究

为了解决无保护层的煤层区域瓦斯治理的难点,分析了朱仙庄矿煤层及瓦斯赋存状况,提出了在不具备开采保护层的区域内,采用底板穿层钻孔区域防突措施,对掘进巷道进行打钻预抽。在详细介绍底板穿层钻孔的布置、抽采和计量方式的同时,通过理论计算和实际掘进作业两个方面,共同验证了底板穿层钻孔条带预抽区域措施可行性和可靠性,进而为穿层钻孔预抽区域措施在矿区的推广应用提供了范例。     

超高压水力割缝强化抽采瓦斯技术研究

水力割缝是一种重要的强化瓦斯抽采增透技术,现已开始在低透气性突出煤层应用。为了进一步考察其实际效果,选取新集二矿1煤组220112工作面底抽巷实施了100 MPa超高压水力割缝试验。试验结果表明:割缝后,瓦斯抽采纯量平均0.77 m3/min,是未割缝钻孔的瓦斯抽采纯量(0.34 m~3/min)的2.26倍;1煤层组瓦斯抽采钻孔抽采30、60天的抽采有效半径为5 m、7.5 m,极限抽采半径为8 m,相比水力冲孔、未割缝钻孔抽采有效半径显著增加,超高压水力割缝强化抽采瓦斯技术具有广泛的应用前景。     

Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum

When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a mining protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a "main key stratum", will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway (we can also drill them in the drilling field located high in an air gateway). Given the practice in the Halzi mine, the gas drainage rate can reach 73% in the middie coal group, with a gas drainage radius over 100 m.     

Fissure evolution and evaluation of pressure-relief gas drainage in the exploitation of super-remote protected seams

Based on nonlinearity contact theory and the geological structure of the Xieqiao Coal Mine in the newly developed Huainan coal field, rock movements, mining fissures and deformation of overlying strata were simulated by using the interface unit of FLAC3D to evaluate the pressure-relief gas drainage in the exploitation of super-remote protected seams. The simulation indicates that the height of the water flowing fractured zone is 54 m in the overlying strata above the protective layer. The maximum relative swelling deformation of the C 13 coal seam is 0.232%,while the mining height is 3.0 m and the distance from the B8 roof to the C13 floor is 129 m, which provides good agreement with a similar experiment and in situ results. The feasibility of exploitation of a super-remote protective coal seam and the performance of the pressure-relief gas drainage in a super-remote protected layer are evaluated by comparisons with practice projects. It demonstrates that the relieved gas in the super-remote protected layers could be better drained and it is feasible to exploit the B8 coal seam before the C13 super-remote protected coal seam. The method is applicable for the study of rock movements, mining fissures and deformation of the overburden, using the interface unit to analyze the contact problems in coal mines.     

Effect of protective coal seam mining and gas extraction on gas transport in a coal seam

A gas–solid coupling model involving coal seam deformation,gas diffusion and seepage,gas adsorption and desorption was built to study the gas transport rule under the effect of protective coal seam mining.The research results indicate:(1) The depressurization effect changes the stress state of an overlying coal seam and causes its permeability to increase,thus gas in the protected coal seam will be desorbed and transported under the effect of a gas pressure gradient,which will cause a decrease in gas pressure.(2) Gas pressure can be further decreased by setting out gas extraction boreholes in the overlying coal seam,which can effectively reduce the coal and gas outburst risk.The research is of important engineering significance for studying the gas transport rule in protected coal seam and providing important reference for controlling coal and gas outbursts in deep mining in China.     

Principle and engineering application of pressure relief gas drainage in low permeability outburst coal seam

With the increase in mining depth, the danger of coal and gas outbursts increases. In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas. Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained. The practice in the Panyi coal mine has shown that, after mining the Cllcoal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated. The result was that we achieved a safe and highly efficient mining operation of the C 13 coal seam.     

新集矿区煤层气地面开发技术探讨

作为国家煤层气示范开发区,针对新集矿区的地质条件及煤层气储存特点,选用地面垂直井开发煤层气的工艺技术,通过开发试验现场的＂1＋3＂井组工程的三口试生产井,成功地产出了煤层气,获得了单井最大日产气量3 728m3,排采三年后日产气量仍维持1 000m3。对其中的钻井、储层保护、水力压裂、排水、采气方面的关键技术的研究和实施,建立起一套适用于新集矿区地质条件及中国国情的煤层气钻井、完井、压裂和采气工艺技术。试验区地面垂直井开发煤层气的成功实施,也为矿区治理矿井瓦斯,提供了新的途径。     

新集一矿孔隙结构特征研究

为进一步了解新集一矿煤层孔隙结构特征,通过压汞法和低温氮等温吸附法实验手段对新集一矿主采煤层孔隙发育特征进行研究。发现新集一矿主采煤层孔隙度较比两淮矿区其他地区高。其中以8煤层8XJ5号样为代表孔隙分布以小孔最发育,大孔较发育,中孔少见为特征和以13-1煤层13XJ10号样为代表孔隙分布以小孔最发育为特征的基质孔,孔隙之间的连通差,不利于瓦斯的抽排;以11-2煤层11XJ3号样和6-1煤层6XJ15号样为代表中孔发育,孔隙以裂隙性为主,孔隙之间的连通较好,有利于瓦斯的运移。     

保护层开采上覆煤岩变形移动及瓦斯抽采效果

根据潘三矿东四采区实际开采条件和回采工艺,运用数值模拟和现场试验相结合的方法,分析了近水平煤层保护层开采过程中被保护层应力、变形量、透气性系数在保护层开采过程中的演化机制。结果表明：保护层开采过程中,被保护层存在未受影响区（原始应力区）、增压区、过渡卸压区、稳定卸压区和重新压实区,被保护层边界区域附近过渡卸压区内的透气性系数为原始透气性系数的30倍左右,煤体应力下降,产生了一定的膨胀变形,大大提高了瓦斯抽采效果。