大水头煤矿综放工作面瓦斯综合防治技术研究

大水头煤矿为高瓦斯矿井,地质构造复杂,煤层具有自然发火特征,煤尘具有爆炸性。结合煤矿矿井瓦斯地质,确定了适合本矿的综放面瓦斯综合防治技术。在工作面采用一进二回"B"型、一进一回"U"型通风系统以及采前预抽、边采边抽、采空区埋管抽采等综合抽采方法,保证了工作面上隅角、回风顺槽等瓦斯浓度不超限,防止了瓦斯事故的发生,实现了矿井的安全生产。     

Coalbed methane: From hazard to resource

Coalbed gas, which mainly consists of methane, has remained a major hazard affecting safety and productivity in underground coal mines for more than 100 years. Coalbed gas emissions have resulted in outbursts and explosions where ignited by open lights, smoking or improper use of black blasting powder, and machinery operations. Investigations of coal gas outbursts and explosions during the past century were aimed at predicting and preventing this mine hazard. During this time, gas emissions were diluted with ventilation by airways (e.g., tunnels, vertical and horizontal drillholes, shafts) and by drainage boreholes. The 1970's ‘energy crisis' led to studies of the feasibility of producing the gas for commercial use. Subsequent research on the origin, accumulation, distribution, availability, and recoverability has been pursued vigorously during the past two decades. Since the 1970's research investigations on the causes and effects of coal mine outbursts and gas emissions have led to major advances towards the recovery and development of coalbed methane for commercial use. Thus, coalbed methane as a mining hazard was harnessed as a conventional gas resource.     

高产高效矿井煤层瓦斯抽采工艺优化

瓦斯灾害因成灾类型多,瓦斯矿井分布广,灾害事故影响大,已成为我国多数煤矿常见自然灾害之首。当前瓦斯治理较为广泛的方法是运用瓦斯抽采技术,降低煤层残余瓦斯含量,而采用何种抽采工艺既能高效的消除瓦斯灾害威胁,又能保证良好的效益是需要权衡的关键问题。以我国高产高效工作面为试验区,通过开展多种瓦斯抽采工艺的对比试验,揭示了各类抽采钻孔在不同抽采孔径、不同间距、不同布置类型等工艺条件下的抽采参数特征,进而得出符合矿井实际的最优工艺类型及最优参数,为矿井的高效抽采提供重要依据。     

Measurement of pressure drop in drainage boreholes and its effects on the performance of coal seam gas extraction: a case study in the Jiulishan Mine with strong coal and gas outburst dangers

Although it is a well-accepted belief in the petroleum industry that horizontal well productivity can be limited by the pressure drop within the wellbore, little has been reported regarding how this pressure drop affects gas extraction from a coal seam and its further effects on mitigating coal and gas outburst dangers in coal. One of the major reasons for this scarcity is that the pressure-drop distribution in horizontal drainage boreholes is difficult to obtain. In this study, measurements of pressure drops in 54 drainage boreholes were performed in the No. 2₁ coal seam, which is the primary mining layer of Jiulishan Mine and poses a strong danger of coal and gas outbursts. Next, a coupled governing finite-element model, which includes the pressure drop in the borehole, Darcy flow in fractures, gas diffusion in the matrix blocks, and the dynamic evolution of the permeability of coal, was developed and implemented using a finite-element method to quantify the pressure-drop effects. Field tests of the pressure drops indicate that the pressure increases in a parabolic form with the increasing depth of the borehole, and lower outer end pressure is associated with larger pressure increments. The numerical results indicate that the pressure drop does affect the coal seam gas extraction, the pressure around the borehole increases with increasing borehole depth, and the increment of the pressure becomes larger when the borehole’s drainage effect is enhanced. However, the impact is small and can be ignored in engineering.     

Mining thin sub-layer as self-protective coal seam to reduce the danger of coal and gas outburst

In response to the severe situation of coal mine gas disaster in China, a new method of reducing the danger of coal and gas outbursts and improving gas drainage and utilization in coal mines was introduced in this paper. The main idea of this method is to mining thin sub-layer as self-protective coal seam to eliminate or reduce the danger of coal and gas outburst. This method can be implemented by drills along seam and hydraulic jet when the mined seam with a relatively weak risk of coal and gas outbursts is soft or has a soft layer. This method was first applied in the Yian mine to verify its effectiveness. The results of application showed that mining thin sub-layer as self-protective coal seam can effectively eliminate the danger of coal and gas outburst and improve gas drainage and utilization. As this method needs less time and lower cost than conventional protective layer mining, it is of great significance for mining coal seam with the danger of coal and gas outburst.     

Application of in-seam directional drilling technology for gas drainage with benefits to gas outburst control and greenhouse gas reductions in Daning coal mine,China

Gas outburst disasters are becoming more serious as the underground coal mines become deeper in China, and a thick zone of deformed coal provides conditions favorable to coal and gas outbursts. The Daning coal mine’s main mining seam is the No. 3 coal seam with coal and gas outburst hazard, which often contains two normal coal sub-layers and one deformed sub-layer. Considering both the geological conditions of the coal seam and applications of the in-seam directional longhole drilling technology, a new schematic diagram of in-seam directional longholes for gas drainage is developed. The two borehole layout models of longwall panel and main entries for gas outburst disasters control have been successfully applied. The gas drainage rates of both models are >70 %, and the residual gas contents are both <8 m³/t, which can be considered that the gas outburst disasters were effectively controlled. To better guide gas drainage, gas drainage normal and failure modes have been obtained. Although in-seam directional longhole technology has been successfully applied for regional gas drainage with benefits to gas outburst control, there are also some problems that are detrimental to greenhouse gas reductions in gas drainage and gas utilization. The three main problems are air leakage failure in gas drainage, decreasing gas concentration and a low gas utilization ratio. To address the problems mentioned above, five improvements are suggested.     

煤层瓦斯卸压抽放动态过程的气-固耦合模型研究

根据瓦斯渗流与煤体变形的基本理论,引入煤体孔隙变形与透气性演化的耦合作用方程,建立了考虑煤层吸附、解吸作用的含瓦斯煤岩固-气耦合作用模型。应用该模型模拟研究了不同压力影响下瓦斯抽放过程中煤层透气性的演化和抽放孔周围瓦斯压力的变化规律,其结果对于深入理解瓦斯抽放作用机制并采取相应的瓦斯预防和控制措施等具有重要的理论和实践意义。     

贵州省岔河勘探区主采煤层瓦斯压力分析

分析岔河勘探区龙潭组主要煤层6号煤瓦斯压力的实测结果,及部分钻孔依据煤层瓦斯含量计算的瓦斯压力,得出该主采煤层瓦斯压力均大于煤层突出危险性指标的临界值0.74MPa,说明该区主煤层存在突出危险性。比较实测瓦斯压力与计算结果,认为计算结果偏小的原因与煤层瓦斯含量有关：一是在钻具提升过程中部分瓦斯逃逸,造成煤样解吸测定过程中累计解吸的气体量变小;二是气体损失存在误差;三是解吸化验时间过长,产生泄出现象,导致实测瓦斯含量偏小。     

穿层爆破在南桐矿瓦斯抽放中的应用与数值模拟

穿层抽放是一些高突矿井常用的瓦斯治理手段,在穿层抽放时采用爆破技术已被证明具有良好的抽放效果。以重庆市南桐矿穿层爆破为背景,建立了穿层深孔爆破数学模型;利用数值计算和现场实测抽放数据相结合的方法,分别研究了各爆破孔、控制孔动应力的变化以及爆破应力场强度与抽放效果的关系。研究结果表明,穿层抽放的特点决定了爆破孔与抽放孔的布孔方式。由于炮孔斜穿煤层,煤层各断面动应力场分布极不均匀,药包中心控制孔所受动应力为控制孔中最大。在南桐矿薄煤层试验条件下,药包长度为3.2 m的爆破孔平均破坏半径为0.57 m,较其他两排炮孔大20%以上。炮孔中药包长度是影响瓦斯抽放量的重要因素。爆破孔的平均单孔抽放量较控制孔高55%,爆破钻场较非爆破钻场平均单孔流量大49%。     

底板梳状长钻孔替代穿层钻孔瓦斯抽采技术可行性

底板岩巷穿层钻孔抽采技术和本煤层定向长钻孔抽采技术是目前高瓦斯和突出矿井回采工作面最为主要的瓦斯治理措施。晋城矿区赵庄矿煤层具松软低透气性特点,主要采用岩巷穿层钻孔消突为主,本煤层顺层钻孔消突为辅的瓦斯治理方法。但底板岩巷穿层钻孔存在工程量大、施工周期长及成本高等缺点,本煤层钻孔存在钻孔抽采不均匀、钻孔覆盖密度不足等技术缺陷。为对比考察底板梳状长钻孔与底板岩巷穿层钻孔的抽采效果,在赵庄矿1307采面开展了2种瓦斯治理方法。结果表明:抽采条件和抽采范围相同条件下,5个底板梳状长钻孔的瓦斯抽采总量占到底板岩巷穿层钻孔瓦斯抽采总量的75.4%,而底板梳状长钻孔的经济投入仅占底板岩巷穿层钻孔经济投入的29.2%。由此得出,研究区梳状长钻孔替代穿层钻孔的瓦斯抽采技术是可行的。该研究为底板梳状长钻孔替代底板岩巷的技术可行性提供了实践参考,为松软低透的高瓦斯和突出矿井的瓦斯治理提供了更为经济可行的治理方案。      

碎软煤层顶板梳状长钻孔水力压裂区域瓦斯高效抽采模式

瓦斯区域超前治理是实现煤矿安全、高效及智能化开采的重要保障,针对碎软煤层区域瓦斯高效抽采难题,以陕西韩城矿区3号煤层为研究对象,提出井下煤层顶板梳状长钻孔水力压裂区域瓦斯抽采模式。采用理论分析、数值模拟和现场试验等多手段相结合的方法,验证模式适用性,阐明紧邻煤层顶板梳状钻孔压裂裂缝延展规律、抽采机理和压裂曲线特征,进而建立适用于500 m孔深的集地质条件动态分析、分段水力压裂、封隔器遇阻解卡和压裂范围连续探查于一体的顶板梳状长钻孔裸眼分段水力压裂关键技术体系,实现煤层顶板梳状钻孔主孔轨迹距离煤层5 m左右、多段均匀压裂、压裂范围全孔监测和孔内事故高效处理。以此为基础,在韩城桑树坪二号井开展2孔次的工程实践：压裂主孔深度588 m、距3号煤层2 m左右,单孔压裂6段,压裂范围探查深度381 m、压裂影响半径20 m以上;压裂后,钻孔抽采瓦斯平均体积分数40%以上、瓦斯抽采量1 m3/min以上,抽采效果是常规钻孔的4倍,120 d瓦斯抽采有效半径可达9 m,实现了碎软煤层瓦斯区域高效抽采。并提出了适用于碎软煤层大区域瓦斯抽采以及高瓦斯压力碎软强突煤层远程区域抽采卸压等规模化应用技术思路。     

Simulation of an enhanced gas recovery field trial for coal mine gas management

Coal mine gas management has evolved from being predominantly dependant on mine ventilation systems to utilising sophisticated surface based directional drilling for pre-drainage of coal seams. However the advent of enhanced gas recovery techniques in the coalbed methane industry has provided an opportunity to address gas management objectives hitherto impractical. Specifically: achieving very low residual gas contents to mitigate against frictional ignitions and fugitive emissions; the means to accelerate gas drainage to accommodate mine schedule changes; and to enable pre-drainage of coal reserves with very low permeability. This article examines a possible enhanced gas recovery field trial at an Australian mine site. Production data from four surface to inseam medium radius gas drainage boreholes was modelled and history matched. The resulting reservoir characteristics were then used to model the performance of the boreholes using an enhanced recovery technique. One of the boreholes is modelled as an (nitrogen) injection well and two flanking wells are modelled as production wells.The model results suggest that accelerated gas flow rates as well as very low residual gas contents are achievable using typical coal mine gas drainage infrastructure and goaf inertisation systems.     

煤矿隐伏小断层的瓦斯抽采钻孔探测方法

断层对煤与瓦斯突出危险性影响较大,准确探测断层位置对预防灾害具有重要作用。目前,煤矿进行采掘作业之前,施工大量瓦斯抽采钻孔,但是这些钻孔包含的地质信息未被充分重视,为此,提出了利用穿层、顺层瓦斯抽采钻孔群探测隐伏断层的技术方法。通过建立瓦斯抽采钻孔探测断层的数学模型,计算断层面、煤层底板的三维坐标,通过绘制煤层底板等高线图及其三维图,确定断层位置、落差、产状和断层性质等基础参数。基于Matlab软件的图形用户界面（GUI）工具,编写了瓦斯抽采钻孔探测断层的软件,实现了断层信息的可视化,为准确判识断层提供了技术平台。通过钻孔定位、模型计算、图像处理、断层识别等综合技术方法,成功实现了利用瓦斯抽采钻孔进行隐伏小断层探测。      

负角度定向长钻孔瓦斯抽采完孔工艺研究

定向长钻孔预抽煤层瓦斯是实现煤矿瓦斯区域超前治理的有效技术手段,受采掘部署影响,负角度钻孔（下向孔）在生产中应用广泛。中硬煤层成孔性好、通常无需护孔,但针对负角度长钻孔积水问题,现有常规方法均无法有效解决。以贵州龙凤煤矿9号中硬煤层下向长钻孔为研究对象,在同一区域施工2组定向长钻孔,钻孔平均倾角–8°,钻孔孔深240~363 m、垂深40.0 m,对比分析了长距离、大垂深定向长钻孔护孔和未护孔2种完孔工艺的瓦斯抽采效果差异。结果表明:在抽采前期,采取护孔工艺的负角度定向长钻孔平均瓦斯抽采量为2.09 m3/min,未采取护孔工艺的为1.87 m3/min,二者差别不大;但护孔工艺定向长钻孔瓦斯抽采量衰减系数是未护孔的61.54%,以抽采400 d为例,护孔工艺定向长钻孔瓦斯抽采总量是未护孔的1.40倍;经理论计算,采取筛管护孔工艺钻场抽采达标时间比未护孔钻场缩短了157 d。从长期抽采效果来看,在缺乏有效排水措施的前提下,采取护孔工艺能够有效提高负角度定向长钻孔的瓦斯抽采效果。      

地面垂直钻孔预抽特厚煤层瓦斯数值试验与应用

为解决塔山煤矿高强度开采条件下瓦斯低含量、高涌出的问题,同时为了弥补大型物理实验和现场试验成本高、操作难的缺点,根据该矿8101工作面所属区域煤层的地质和瓦斯赋存条件,确定了数值试验方案,对地面垂直钻孔预抽特厚煤层瓦斯的效果进行优化分析。基于煤岩（体）的孔隙特征,构建了含瓦斯煤岩（体）破裂过程气-固耦合和渗透率-损伤耦合数学本构模型。采用RFPA2D瓦斯分析版软件建立地面钻孔抽放瓦斯的数值计算模型,设置有关简化条件、边界条件和物性参数,通过数值试验得出：地面垂直钻孔的终孔位置布置在煤层底部比较合理;在综合考虑地面垂直钻孔投入成本和瓦斯抽采效果的基础上,确定地面垂直钻孔间距为50～60 m比较合理。同时,由8101工作面地面垂直钻孔抽采煤层瓦斯的实际应用效果分析可知,当地面垂直钻孔的终孔位置布置在煤层底部,且钻孔间距布置为50 m时,能够实现良好的瓦斯抽放效果,这也从一定程度上进一步验证了数值试验的合理性和可行性。     

保安煤矿西翼3煤层开采安全性研究

通过对矿区水文地质条件的分析,认为开采3煤层时的主要充水含水层为顶板砂岩裂隙水和底板奥灰水,以奥灰水最为突出。采用突水系数法及阻水系数法计算煤矿西翼3煤层开采的有效隔水层厚度为37.6m,运用大井法计算工作面开采过程中最大涌水量为98.3m3/h。研究认为：工作面可以进行带压开采,在巷道和工作面开拓中必须在井下施工探放水孔,在富水区进行疏水降压,达到安全开采的目的;开采F20、F35断层附近时应留足防水煤柱,并对奥灰进行疏水降压,以免发生突水事故。     

突出煤层CO2气相压裂高效抽采防突掘进技术

我国煤矿煤与瓦斯突出灾害严重影响煤矿安全生产。尽管近10年来这一灾害事故大幅度减少,但恶性事故依然发生,给矿工生命和煤矿安全生产造成严重损失。国内外现阶段的防治瓦斯突出技术,如水力压裂、水力割缝、水力冲孔、深孔爆破、密集钻孔等,不同程度地解决了防突安全掘进,但对于一些高瓦斯低渗透突出煤层,上述技术还难以从根本上解决消突安全快速掘进。所以,防突技术仍然是我国煤炭领域亟待攻关的重大科技难题。选取山西寿阳县新元煤矿31002工作面为试验案例,介绍CO₂气相压裂技术方法,并探讨其防突掘进效果。新元煤矿开采的山西组3号煤层为低渗透突出煤层,前期主要采用密集钻孔预抽瓦斯防突措施,抽采达标时间长,掘进速度慢。高效抽采瓦斯,防止煤与瓦斯突出,保障煤巷安全快速掘进,是新元煤矿安全高效生产的重大技术难题。在新元矿采取的气相压裂措施概况如下:在掘进工作面前方实施双钻孔气相压裂;完成9个瓦斯抽采钻孔以覆盖巷道两侧各15 m安全范围;全部11个钻孔联网抽采3~5 d,防突参数K₁值达标后恢复掘进。试验数据表明,气相压裂抽采防突技术措施的强化抽采效果显著,抽采效率大幅度提高,煤炮等动力现象减少,K₁值降低,掘进割煤时巷道瓦斯浓度得以降低和均化,保障了连续安全掘进。实践证明,CO₂气相压裂技术能够实现连续安全快速掘进理技术,在全国类似瓦斯地质条件煤矿中具有推广应用意义。      

深部硬煤掘进工作面煤与瓦斯突出机制探讨

为深入探讨硬煤的煤与瓦斯突出机制,对深部硬煤掘进工作面煤与瓦斯突出的相关理论和模型试验进行研究。根据断裂力学、岩石力学及煤与瓦斯突出有关理论,提出深部开采过程中硬煤掘进工作面薄板理论假设,并将该理论应用于深部硬煤掘进工作面煤与瓦斯突出模拟试验研究。对硬煤掘进工作面薄板理论分析,认为工作面尺寸、煤的弹性模量、围岩侧压系数、瓦斯压力等因素对硬煤掘进工作面突出具有较大影响。试验结果表明,在围岩应力、煤的坚固性系数较大的情况下,硬煤突出临界条件主要受围岩应力、煤的弹性模量、围岩侧压系数及工作面尺寸等因素影响,而受瓦斯压力影响相对较小;在围岩应力、试样的坚固性系数较大且煤的弹性模量和侧压系数稳定不变的情况下,发生突出的临界轴向应力随模拟工作面尺寸增大而近似呈线性减小。试验结论基本符合本硬煤突出薄板模型理论公式,在一定程度上验证了硬煤掘进工作面煤薄板模型理论及硬煤掘进工作面突出机制假设。     

Numerical simulations for coupled rock deformation and gas leak flow in parallel coal seams

Based on the new viewpoint of interaction mechanics for solid and gas, gas leakage in parallel deformable coal seams can be understood. That is, under the action of varied geophysical fields, the methane gas flow in a double deformable coal seam can be essentially considered to be compressible with time-dependent and mixed permeation and diffusion through a pore-cleat deformable, heterogeneous and anisotropic medium. From this new viewpoint, coupled mathematical models for coal seam deformation and gas leak flow in parallel coal seams were formulated and the numerical simulations for slow gas emission from the parallel coal seams are presented. It is found that coupled models might be close to reality. Meanwhile, a coupled model for solid deformation and gas leak flow can be applied to the problems of gas leak flow including mining engineering, gas drainage engineering and mining safety engineering in particular the prediction of the safe range using protective layer mining where coal and gas outbursts can efficiently be prevented. This revised version was published online in July 2006 with corrections to the Cover Date.     

汪家寨煤矿煤与瓦斯突出规律及其主控因素分析

汪家寨煤矿是严重的煤与瓦斯突出矿井,依据矿区实际瓦斯地质资料,运用瓦斯地质理论和构造演化理论,研究了区域和井田构造控制特征。分析认为该矿主要以中小型突出、倾出为主,压出为辅;随煤层埋深的增加突出强度增大;C409煤突出最为严重;突出多发生在煤巷掘进面及断层影响带。分析了埋藏深度、顶底板岩性、煤厚及其变化、软分层、地质构造等因素对煤矿煤与瓦斯突出的影响,认为断层及其影响带、厚煤尤其是其增厚部位是煤与瓦斯突出的易发区域,因此断层构造和煤层厚度及其变化控制着该矿突出的发生和分布规律,为煤与瓦斯突出的主控因素。研究成果为矿井突出防治工作提供了理论指导。