顺层钻孔预抽煤层瓦斯区域防突关键技术研究
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摘要
对于低透气性松软单一煤层突出矿井来说,煤与瓦斯突出的区域防治是一个世界性的难题。由于预抽瓦斯措施工程量大、费用高、时间长、效果差,煤与瓦斯突出事故难以杜绝,安全生产难以保证。本研究通过对顺层钻孔的成孔机理研究,提出了顺层钻孔深孔施钻的“孔内高压”施钻理论,提高了顺层钻孔在低透气性松软煤层施钻深度,解决了顺层钻孔预抽区段煤层瓦斯区域防突措施不能覆盖一个区段的问题；提出了“孔间煤体水力压裂卸压增透”技术,通过理论研究,计算机模拟,现场试验,使空间煤体地应力释放、煤体透气性增加,提高了瓦斯抽采的浓度和流量,大幅度减少了抽采达标时间。本研究的研究成功,为单一低透气性松软突出煤层开辟了一条与开采保护层有相似效果的防突新路。
顺层钻孔预抽煤层瓦斯区域防突措施非常适应单一低透气性突出煤层矿井现场的条件,具有防突费用经济、钻孔容易布置、钻机施工方便、防突效果明显等优点,在防突规定中被列为优先选择的措施。但是,这一区域防突措施没有得到有效的运用。究其原因,主要存在如下问题：
(1)由于突出煤层煤层软,透气性低,瓦斯含量和压力大,垮孔、喷孔严重等限制,上山钻孔钻进深度超不过80米,下山钻孔的深度超不过60米。钻孔覆盖范围不能达到一个区段。
(2)顺层预抽钻孔的布孔密度是一个两难命题,钻孔间距大,影响钻孔的预抽及区域消突效果；钻孔布置较密,在接近或穿过相邻钻孔瓦斯喷孔影响区域时,造成因钻孔周围煤体应力不均匀使钻孔产生偏移、甚至钻孔内压风从相邻钻孔内排出。
(3)单纯的顺层钻孔预抽措施对消除地应力、构造应力的集中区域效果不理想,而地应力、构造应力的集中区又影响着煤层的透气性,采取预抽措施后仍有突出事故发生。
(4)顺层钻孔预抽煤层瓦斯区域防突措施的预抽达标期太长,如果把瓦斯含量降到8m3/t以下,预抽期高达20～24个月,正常的采掘接替无法进行。
(5)单纯的高压水力压裂技术作为区域防突措施有很大的缺陷。一是水力压裂技术的压裂区域不能人为控制,无法预知水力压裂的影响区域的准确范围；二是在使压裂区域产生卸压的同时,由于煤体的水平位移,会在压裂影响区域之外形成应力升高区或者应力集中区。防突存在盲目性。
本研究的主要针对上述问题,对深孔钻进和孔间煤体压裂卸压增透两个关键技术进行研究。
一、顺层钻孔深孔钻进方面：
实际打钻中,钻孔排出的钻屑远远大于钻孔的理论计算排渣量。在打钻的过程中,由于地应力、瓦斯应力的作用,在钻孔的周围会形成塑性变形区,而大量喷出瓦斯和煤粉,则是一种孔内动力现象。主要表现为塌孔、喷孔和卡钻等。塌孔是在地应力、瓦斯应力的作用下,加上煤质松软,钻孔孔壁经常出现垮塌现象。由于地应力集中、瓦斯应力高,加上煤体松软,钻孔钻进时极易发生喷孔,甚至发生煤与瓦斯突出,伴随着钻孔的钻进喷出大量的瓦斯和煤粉。由于喷孔主要发生在孔底或孔底附近,喷孔极易形成“孔穴”,使钻头失去钻孔壁的约束,形成钻头“扫孔”现象,孔穴越来越大,直至钻孔报废；喷孔还会造成后部钻孔壁应力增加,变形加剧,形成卡住钻杆等现象。卡钻是与喷孔有直接联系且随之发生的一种现象,喷孔发生造成孔壁变形,加上孔内煤粉的堆积,将钻杆和钻头箍紧。
1.顺层预抽钻孔施钻期间孔内瓦斯流动状态
钻孔施钻过程中,瓦斯流动和涌出的形式是不同的。从孔底到孔口的瓦斯流动状态分为三类：即球向不稳定流动、径向不稳定流动、径向稳定流动。
由于煤层深部煤层处于原岩应力状态,钻孔孔底在不断向煤体深部钻进延伸,钻头持续切割煤体,在钻孔孔底孔壁很难在短时间内形成稳定的塑性区,塑性区很薄,甚至近似为0。对于严重的突出煤层来说,瓦斯含量高、压力大,煤层透气性差、瓦斯解吸快,高压瓦斯和地应力联手,共同作用在钻孔孔底薄壁上。孔底的瓦斯球向不稳定流动致使孔壁煤体的层状剥落,然后不断向煤体深部扩展,形成瓦斯喷孔、塌孔,有的还会发展成为钻孔内煤与瓦斯突出。因此,球向不稳定流动段是影响钻孔成孔的最重要因素。
2、孔内高压理论的提出
有效遏制打钻时孔底的异常瓦斯涌出的动力现象,使球向不稳定涌出削弱后移,使径向不稳定段长度延长,是提高顺层钻孔打钻深度重要的途径。由达西定律可知,钻孔瓦斯涌出的动力,就是煤层原始瓦斯压力(P0),和孔内气体压力(p1)之压力差,如果提高施钻时空压机供风的压力,通过优化钻孔、钻具的参数,在钻孔孔底附近形成一个高气压环境,就会降低煤层内原始瓦斯压力(P0)和钻孔内气体压力(p1)之间压力差,孔底煤体吸附瓦斯急剧解吸并涌入钻孔孔底的猛烈程度就会减弱,孔底孔壁就能削弱和减少层状式剥落,钻孔持续钻进,孔底持续延伸,瓦斯的球形不稳定涌出形式,变为涌出相对不剧烈的径向不稳定流出,拉长了径向不稳定流动段的长度。瓦斯压力梯度变小,孔壁就能保持稳定,从而提高钻孔施钻深度。
3.施钻参数的选择
孔底压力决定了打钻时的排渣能力,孔底风压把煤屑加速到一定的速度,并在钻孔内搬运排出孔外。从p=△Pa+△Psac+△Ps+P0可以看出,孔底压力p越大,则△Pa、△尸Psac、△Ps就越大,排渣能力则越强。
而p=P-△Pt-△Pz即孔底压力决定于空压机提供的管道内压力,以及空气在钻杆内的阻力损失△Pz、压缩空气通过钻头的局部阻力△Pt
所以,要在钻孔直径一定的情况下,在保证排屑通道断面的前提下,缩小钻孔与钻杆之间的空间,提高钻孔内的风速则能提高搬运能力。提高空压机输出管道内的风压,增加钻杆内径减小风阻,改善钻头出风形式,降低局部阻力,就能确保孔底风压。
根据焦作矿区多年的实践,选择钻孔孔径为89mm；优化钻孔直径与钻杆直径比。选择直径73mm钻杆。根据焦作矿区原始瓦斯压力,考虑压缩空气使用的安全,合理风压选择为0.7-0.8Mpa之间。
4、钻具(1)二次扩孔钻头钻头(专利号：ZL201020124318.8)
钻头钻径越大,孔底的球向不均衡瓦斯涌出就越剧烈；钻径增大,孔壁的支撑能力则会减低。反之,小直径钻头对孔底喷孔的诱导越小,成孔更容易。基于这个原理,提出了二次扩孔分次卸压的概念。该钻头由两部分组成,前端为43mm小直径钻头,后部为89mm钻头,两者距离800-1000mm,前方的小直径钻头施工小直径钻孔,释放瓦斯压力,在小直径钻孔的周围形成应力梯度；然后由后部的扩孔钻头,将钻孔扩大89mmm直径。
(2)等直径钻杆(专利号：ZL201020124316.9)
“等直径钻杆”是在光面钻杆上焊接钻翼,排渣通道位于钻翼之间,钻杆旋转搅动钻孔里沉积的煤尘并被压风吹出,解决了光面钻杆钻屑沉积,无法排出摩擦生热的问题,同时,“等直径钻杆”直径与钻头直径基本一致,使钻杆钻头旋转、切割更稳定,也解决了钻孔的定向问题。
4.现场试验。本研究先后在焦煤集团公司古汉山矿、中泰矿业有限公司进行试验。古汉山矿现场试验自2009年7月开始,到2009年10月现场试验基本结束,共施工上下向钻孔493个,钻孔深度最低深度103米(个别其他原因失败钻孔未计),最深钻孔达到135米,平均深度米118米。中泰公司现场试验自2010年11月开始试验,到2011年2月结束,施钻深度由平均34米,提高到孔深超过90米孔数占72.8%；九里山矿16采区多个采掘地点钻进深度均能达到130m以上。为了使孔间煤体压裂试验更准确,在16161运输巷试验现场设计孔深为120米。
二、孔间煤体压裂卸压增透方面
孔间煤体水力压裂技术的提出是基于对煤与瓦斯突出机理的分析,煤与瓦斯突出是地应力、瓦斯应力以及煤体结构综合作用的结果,实施区域防突措施应当着眼上述三个方面消突。针对突出煤层透气性差,顺层钻孔预抽区段煤层瓦斯区域防突措施工程量大、预抽达标期长、削减地应力构造应力乏力的缺陷,孔间煤体水力压裂技术使煤体固有裂隙扩张的同时,使压裂煤体向自由孔形成的自由面扩张,卸压增透,煤体的塑性增加。孔间煤体水力压裂分以下几个步骤：
1.按理论计算的孔间距施工顺层钻孔,注水压裂孔、自由孔交替布置；
2.对自由孔进行冲孔,扩大等效直径。方法是：自由孔施钻完毕,对孔口段10米扩孔,采用内径l00mm的PVC管用聚氨酯进行封孔；更换水力冲孔钻头钻杆,对自由孔进行水力冲孔；
3.采用注浆封孔工艺,对注水孔进行注水泥浆封孔,封孔长度18米；
4.通过注水孔对孔间煤体实施高压水力压裂；
5.压裂以后,将所有压裂孔、自由孔联网抽放。
孔间煤体水力压裂技术研究分如下几个方面：
1.通过对国内外水力压裂技术的研究现状、研究动向和进展的充分调研,理论分析、计算机数值模拟、现场试验、综合分析相结合的方法进行研究。
2.孔间煤体压裂中煤体破坏,是高压水在钻孔壁造成张拉,继而产生裂缝,高压水充满并支撑裂缝,并使裂缝尖端不断劈裂。持续高压注水,高压水克服煤体内部摩擦力,迫使煤体逐渐向自由孔方向产生位移。首先产生Ⅰ型(张开型)裂纹；然后,克服煤层之间的摩擦力和凝聚力,产生Ⅱ型(滑开型)裂纹；最后,煤体部分或整体向自由端移动,应力得到释放。
理论分析得到钻孔周围起始开裂压力为：Pb=0.29σ1+To+Po+Pc。
维持裂缝扩展的注水压力,
3.根据九里山矿上覆盖岩层垂直应力及试验工作面煤层的泊松比,计算孔间煤体压裂的注水压力P应大于14.78MPa,但低于20Mpa。根据焦作矿区水力冲孔等效直径,计算等效断面为0.6079m2。借鉴淮南保护层开采被保护层变形量4%o,透气性系数增加300倍的经验数据,按孔间煤体变形量4‰计算,孔间距不应超过10.855m。考虑一定的系数,孔间距取6m。
4.孔间煤体处于三向不对称受力状态,垂直方向受到垂直应力σY,水平方向受到侧向应力σx及σz,工作面巷道一侧处于不受力状态,注水孔径向表面及孔底则承受水压力。对煤的力学性质进行假设分析,假设工作面前方煤体是均质、连续和各项同性的；假设煤体是线弹性体,遵循虎克定律；假设煤体只在地应力、水压力作用下变化,忽略瓦斯压力的作用,且不考虑应力、瓦斯压力、水的耦合作用。据上述分析建立了孔间煤体压裂的数值模拟力学模型。
5.采用RFPA2D数值分析软件对低透气性煤层进行水力压裂数值分析,模拟水力压裂的过程,证实孔间煤体压裂卸压程度、透气性系数增加远高于没有自由面的高压水力压裂。孔间煤体压裂能够有效地释放煤体内积聚的潜能,应力集中峰值降低,卸压增透消突效果明显。
6.现场试验选择在焦煤集团公司九里山矿,该矿为煤与瓦斯突出危险矿井。瓦斯绝对涌出量为48.53m3/min,相对瓦斯涌出量为24.17m3/t。煤层瓦斯压力均在0.75mpa以上,最高达2.08mpa,煤层瓦斯含量22.05m3/t。该矿建矿以来共发生煤与瓦斯突出65次,突出规模最大的一次发生在2011年10月27日的16031回风巷突出事故,突出煤量3246t,涌出瓦斯量29.12万m3。试验地点位于16161运输巷,该巷道沿煤层顶板布置,净断面11.04m2,采用锚网加预应力锚索支护方式。采用压入式通风,2×30KW的对旋式局部通风机通风。实际工作风量为550m3/min。布置试验钻孔19个,设计孔深120米,孔间距6米,其中1、3、5、7、9、11、13、15、17、19为自由孔,2、4、6、8、10、12、14、16、18为注水孔。试验区段走向长108米,倾斜宽120米。7.现场试验结果：2012年2月15日至3月8日顺层钻孔施钻、冲孔；2月18日压裂结束后带抽,至8月26日,累计抽放瓦斯量1820943.7m3,抽采率达67.8%,瓦斯含量降至6.91m3/t。实测煤层透气性系数增加420倍。与14121准备工作面(里段)相比(抽采达标评判报告)：煤炭储量25.58万t,瓦斯储量为438.95万m3。工作面共有抽采钻孔949个,合计孔深83239m,自2010年5月到2012年3月,抽采瓦斯量248.36万m3,计算煤层残余瓦斯含量为7.45m3/t。与16161运输巷掘进时采用煤巷密集钻孔区段预抽相比：评价区域内的原始瓦斯含量为21.46m3/t、平均煤厚为7m、煤炭储量2.95万t、瓦斯储量63.3万m3,钻孔总长度9687m,开抽时间为2011年3月1日,累计抽采时间6个月,瓦斯累计抽采量为32.2万m,瓦斯抽采率50.8%,残余瓦斯含量10.5m3/t。由此可见,孔间水力压裂技术优势明显。
8.现场试验时,随着注水孔注水压力的升高,孔间煤体进入裂隙扩展阶段以后,临近的自由孔有大量的瓦斯涌出。事实证明高压注水对煤体瓦斯的驱离作用、对吸附瓦斯的置换作用的存在。水分子的分子结构更适合吸附,水与C02、N2等气体相比,安全性更高。驱离或置换瓦斯的机理有待于我们进一步进行研究。
本课题的研究,解决了长期困扰单一突出煤层矿井的防突问题,使顺层钻孔预抽区段煤层瓦斯区域防突措施的应用更加灵活,工程量更低、抽采达标时间更短。将会进一步增强措施的可靠性,降低防突成本,彻底扭转突出矿井的经营困局。
Outburst mine with low permeability and soft and single seam, regional coal, gas outburst prevention and control have been a problem. For gas pre-drainage measure project amount is large, high cost, long time, poor effect, coal and gas outburst accident is difficult to stop and guarantee the safety in production. Through the study on the bedding of drilling hole mechanism research, the paper puts forward the theory named natural drilling and deep-hole boring " hole high pressure"; The study increases boring depth for the bedding drilling in soft coal seam with low air permeability and solves problem which gas regional outburst prevention measures cannot cover a section for the bedding hole pre-pumping section coal seam. Through the technology research on holes between the coal fracturing, computer simulation, field test, stress release of regional coal body, coal gas permeability increase, this study improves gas drainage rate, shortens the extraction time. The study opens up a new road with similar effects to mining protection layer for a single low permeability and soft coal seam with outburst.
Because of its adaptation to single outburst coal mine site conditions,regional outburst prevention measures based on Bedding hole pre pumping gas has total cost low, flexible arrangement, more apparent effect, convenient drilling construction.It was listed as the priority choice of measures in outburst prevention provisions. However, this regional outburst prevention measures has not been effective used. Following problems are reasons:
(1) Due to the single outburst coal seam poor permeability, low intensity, big gas pressure, severe nozzle hole and collapse hole, the drilling depth of not more than80meters, down the hole depth not more than60meters. Borehole coverage can not achieve a section.
(3) Hole density based on Bedding pre-draining hole density is a dilemma. Large borehole spacing affects gas drainage and regional outburst elimination; Dense borehole layout close to or through the adjacent borehole gas jet area will cause drilling deviation and even discharge the borehole pressure air from adjacent the borehole by the drilling of coal body around the uneven stress.
(3) Draining measures Only by natural drilling to eliminate stress, in tectonic stress concentrated area,its effect is not ideal. Crustal stress and structure stress in concentration zone effect coal seam permeability, so taking drainage measures will not still prominent accidents.
(4)There are great defects for a simple high pressure hydraulic fracturing technology as regional outburst prevention measures. Firstly, hydraulic fracturing area can not be controlled artificially, unpredictable fracturing effect region of accurate range. Secondly, in the fracturing area to produce a pressure relief at the same time, as a result of coal body in the fracturing effect of horizontal displacement, there will be high stress concentration zone out of the fracturing effect area. Blindness exists in outburst prevention.
In view of the above questions, this paper begins research about deep holes drilling and hole of coal body fracturing pressure relief in two key aspects.
The first aspect:deep hole drilling in the form of the bedding drilling
In the actual drilling, drilling cuttings from drilling is far greater than the theoretical calculation of the slag amount. In the drilling process, as a result of ground stress, gas stress effect, it forms the plastic deformation zone around a borehole, and a large number of discharge gas and pulverized coal, is a kind of dynamic phenomenon in the hole. The main manifestations are holes collapse, hole drilling, card and so on. Hole collapse affected by ground stress, gas stress, and soft coal, the phenomenon of the collapse will appear on the wall of the hole. Jet hole belongs to dynamic phenomenon in the drilling similar to the coal and gas outburst which is mainly affected by high-pressure gas, stress concentration and soft coal and other factors. Along with the borehole drilling it will spew gas and pulverized coal. Because the jet hole mainly occurs at the bottom of the hole or holes near the bottom, spray hole is very easy to form the "Cavity", which causes the drill bit to lose constraint by holes wall and sweep hole. The Hole will be bigger and bigger until drilling hole is scrapped. Jet holes will cause the stress increases, deformation aggravates and get drill pipe stuck. Sticking and jet orifice has direct contact. Spray hole deforms the hole. With coal accumulation, the drill pipe and the drill bit will be hooped.
1. Gas flow state during drilling hole by bedding pre-draining borehole. The form of gas flow and emission is different in the boring process. From the bottom of the hole to the orifice of the gas flowing state is divided into three categories:namely the ball to the unstable flow, radial unstable flow and radial stable flow.
Due to the deep coal seam in the original rock stress state, borehole bottom in the coal body extending to deep coal, drill bit cutting coal Continuous, it is difficult to form a stable plastic zone in hole bottom and hole wall in a short period of time. Plastic zone is very thin, or even approximate to0. For serious outburst coal seam, with high gas content, large pressure, low permeability and fast gas adsorption and desorption, interaction of high pressure gas and stress is on the thin wall of the drilling holes bottom. Gas spherical flow in hole bottom causes the hole wall to exfoliate, and then develops to deep coal Continuously, so spray hole, hole collapse will develop into coal and gas outburst in the borehole. Therefore, the unstable spherical flow is the most important factor of drilling a hole into a hole.
2. the hole pressure theory
When drilling holes and artificially elongating length of radial unstable flow, curbing abnormal gas dynamic phenomenon effectively in the borehole bottom is an important way to improve borehole depth as pre-draining gas in the coal seam. According to Darcy's law, power source of the gas flow in coal seams is caused by the pressure differential with the original gas pressure of P0, and pressure P1in a drilled hole. If we artificially create a high pressure environment in the drilled hole, Pressure difference between borehole pressure and the original gas decreases, adsorption desorption intensity of gas in the coal seam can reduce. With the continuous drilling borehole, gas emission becomes into radial unstable emission. The gas pressure becomes slow gradually so as to ensure the quality of drilling hole.
3. the application of drilling parameters
Some ways would be used to improve pressure of pre-draining borehole gas in the coal seam to adapt to technology and the requirements of high voltage for drilling a hole, namely, increasing working pressure of air compressor and flow rate of compressed air, reducing pressure loss in the pipeline, optimizing the proportion of boring hole to diameter of drilling-pipe, increasing the diameter of the drill-pipe, reducing the compressed air flow resistance of drilling-pipe, Properly reducing the cross section of discharge channel in the drilling-pipe, Increasing wind pressure and speed of discharge channel.
According to practice of many years in the Jiaozuo mining area, diameter of the hole is made89mm, diameter ratio of a borehole and drilling-pipe is optimized and the diameter73mm of a drilling-pipe is selected. According to original gas pressure of the Jiaozuo mining area, considering safety of the use of compressed air reasonable air pressure is selected for0.7-0.8Mpa
4. drilling tools
(1) Reaming bits (Patent number:ZL201020124318.8)
The bigger is drill diameter, the more intense is the uneven gas emission from of the hole bottom; conversely, the smaller drilling-bit diameter is the smaller Influence drilling-bits cause on the bottom of the hole orifice. Based on this principle, the concept is put forward namely a second counter bore and multiple pressure relief. The drilling-bit is composed of two parts, the distance between two part is800-1000mm. namely, the front end for43mm-diameter small drilling-bit and the rear89mm. The small diameter-drill constructs small-diameter bores, gas pressure is released and the stress gradient is formed around in small diameter hole. Then the rear drilling-bit develops the bore to89mm diameter.
The "Equal diameter drill" is welded the drill wing to the smooth rod and discharge channel is located between the drill wing. Drill rod rotating stirs deposited dust in the drilling hole and presses the wind out. Eliminating the drill-cuttings deposition on the smooth surface and discharging friction heat". Diameter of drill-pipe with equal diameter is basically the same to the diameter of the drill bit which also solves the problem of directional drilling.
4. field tests.
It has been tested about this study in Guhanshan Coal Mine and China and Thailand Mining Company Limited in Coking Coal Group. The field test has been done from2009July to2009October in Guhanshan Coal Mine. A total construction of downward are493holes, hole depth of minimum depth of103meters (the other reason for the failure of individual drilling not counted)the deepest drilling to135meters, average depth of118meters. The field test has been done in China and Thailand Mining Company Limited from2010November to2011February test. The boring depth by a mean is34meters, up to72.8%holes more than90meters deep. The drilling depth all can reach above130metres in sixteenth mining area of Jiuli Hill Coal Mine. In order to make the coal crushing test more accurate between the holes, the hole depth designed is120meters in test site of the16161th transport tunnel.
The second aspect:the coal in pore space fractured under pressure and release
pressure to increase permeability
The hydraulic fracturing technology for the coal in pore space was discovered based on the analysis of theory for coal and gas outburst. The coal and gas outburst happens under the comprehensive effect of ground stress, gas stress and coal structure, on which should be focused when implementation regional outburst prevention measure. Take care of the poor permeability of outburst coal seam, the huge project and the long time limited of outburst prevention measure used in coal and gas areas, and the bad cutting down ground stress, The hydraulic fracturing technology for the coal in pore space, at the time coal natural fissure expanding, makes the fractured coal expand to the free surface formed by the free holes, unloads the ground stress and increases the plasticity
The hydraulic fracturing technology contains the following steps:1. According the theoretical calculated hole space to construct, drilling along the coal seams, the injection water holes and free holes constructed alternately.
2. Take hole punching to free holes, expand the equivalent diameter. The methods are:after drilling the free holes, punch the orifice for10meters, sealing used the polyurethane with diameter100mm PVC pipes; change the drill bits and drill pipes with hydraulic drill to punch the free hole.
3. Using the grouting hole technology to seal the holes, injection slurry18m length.
4. Taking high pressure hydraulic to fracture the coal through injection water holes.
5. Network all fractured holes and free holes to emission gas after fractured the coal.
Researching hydraulic fracturing technology divides into the following aspects:
1. The hydraulic fracturing technology should be researched by full investigation the present situation, research way and progress in home and abroad, theoretical analysis, numerical simulation, field test and comprehensive analysis.
2. During be fractured, the coal destroyed by the high pressure water tensile around the borehole to form fissures, the high pressure water propped fracture, which make the fissures tips continue to prop, expand and extend. With the further injecting water, overcome the friction between coal layers, crush the coal to free holes. First, produce Ⅰ model (open type) fissures; then overcome the friction and cohesion between the seams, form Ⅱ model (sliding type) fissures; at last, part or whole coal body move to free ends, and stress release. The initial cracking pressure analyzed by theories is:Pb=0.29σ1+T0+P0+Pc。
The injection pressure for Maintenance the crack is:
3. According the vertical stress of rock stratum covered on the Jiuli Hill Mine, and the Poisson's ratio of the coal seam in test areas, the injection water pressure for the coal fractured in pore space is more than14.78MPa, and less than20Mpa. According to Jiaozuo mining hydraulic hole equivalent diameter, calculating the equivalent section is0.6079m2. Draw lessons from Huainan Mining, mining the protective layer leads to protected layers deform4‰, the permeability coefficient increases300times, the coal between holes deform4‰, the space between holes is not exceed10.855m, given a certain coefficient, the space between holes is6m.
4. The coal in hole space is in the asymmetric stress state, the vertical stress is σY, the horizontal direction is x and z, one side of the coal tunnel is not stressed, injection water holes are stressed by water in warp direction and bottom. Assumed analysis the coal dynamics properties, the coal in front of the working face is homogeneous, continuous, isotropic, assumed that the coal is linear elastic, followed Hooke's law, the coal body is changed only by ground and water stress, ignore the gas pressure, don't given the effect of stress, gas pressure, water coupling. On the basis of above analysis, establish the numerical simulation dynamics model.
5. Take repeated trial to this model by software RFPA2D, contrast the actual and simulated parameters of stress in coal, displacement, elastic potential and so on. Determine the ultimate model, calculate the other models under different injection water parameters.
6. Filed test is carried in Jiaozuo Coal Group Jiuli Hill Mine, which is coal and gas outburst mine. The absolute gas outburst rate is48.53m3/min, the relative gas outburst rate is24.17m3/t, the gas pressure in coal is average in above of0.75MPa, sometimes is up to2.08MPa, the gas storage in coal is22.05m3/t. Since the mine is built, the mine has happened65times coal and gas outburst, the highest occurred in October27,2011, in the16031returned air alley, the coal outburst quantity was3246t, the gas was291200m3.
The field test site was in16161transport tunnel, which was layout along the roof of coal seam, cross sectional11.04m2, supported by anchor net and anchor cable. This tunnel used the forced ventilation, installed two2x30KW counter local fans, one work the other spare. The actual wind flow was550m3/min. Fixed test19drills, of which1,3,5,7,9,11,13,15,17,19,4,2were free holes,6,8,10,12,14,16,18were water injection holes, designed the hole120m deep, hole space6m., This test section was108m long, tilt wide120m.
7. The field test results:from February15,2012to March8th, drilled along the layers, punched, February18th finished the fracturing and to extract the gas, to August26th, the total drainage gas was1820943.7m3, the extraction rate was67.8%, the gas content was drop to6.91m3/t. the actual test coal permeability coefficient was increase420times
Compared to preparatory work surface named the14121th area (in)(with the report of extraction to standard):coal reserve is255800T, gas content is4389500m3. The work surface extraction drills were949, the total holes' depth was83239m. From May2010to March2012, extraction of gas volume was2483600m3, calculated the residual gas content was7.45m3/t.
Compared with16161transport tunnel during pre-extract by dense drilling in coal tunnel: the regional gas content in evaluated area was21.46m3/t, average coal seam thickness was7m, coal reserves was29500T, gas reserves was633000m3, total drills'length was9687m, started to extract gas in March1st,2011, accumulation pumping capacity was322000m3, The gas pumping rate was50.8%, the residual gas content was10.5m3/t.
From the above comparative analysis, the hydraulic fracturing technology has obvious advantage.
8. During the field tests, along with injection water pressure increases, the coal body begins to crack, a large number of gas emitted around the free holes. The fact have proved that the effect of high pressure injection water to dispel the gas in coal, displace the gas adsorbed on coal exists. The water molecular structure is more suitable to absorption than gas, and has higher security contrast to CO2, N2and so on. The theory of dispelling and displacement of gas needs to further study.
This research topic, has resolved the long term problem that single coal outburst mine how to prevent outburst, and the prevention measures used in gas content areas during drilling along coal layers is more flexible, less engineering, and drop the time to standard. This method will enhance the reliability of preventing outburst, and reduce the cost of preventing outburst, change the management predicament of outburst mines.
顺层钻孔预抽煤层瓦斯区域防突措施非常适应单一低透气性突出煤层矿井现场的条件,具有防突费用经济、钻孔容易布置、钻机施工方便、防突效果明显等优点,在防突规定中被列为优先选择的措施。但是,这一区域防突措施没有得到有效的运用。究其原因,主要存在如下问题：
(1)由于突出煤层煤层软,透气性低,瓦斯含量和压力大,垮孔、喷孔严重等限制,上山钻孔钻进深度超不过80米,下山钻孔的深度超不过60米。钻孔覆盖范围不能达到一个区段。
(2)顺层预抽钻孔的布孔密度是一个两难命题,钻孔间距大,影响钻孔的预抽及区域消突效果；钻孔布置较密,在接近或穿过相邻钻孔瓦斯喷孔影响区域时,造成因钻孔周围煤体应力不均匀使钻孔产生偏移、甚至钻孔内压风从相邻钻孔内排出。
(3)单纯的顺层钻孔预抽措施对消除地应力、构造应力的集中区域效果不理想,而地应力、构造应力的集中区又影响着煤层的透气性,采取预抽措施后仍有突出事故发生。
(4)顺层钻孔预抽煤层瓦斯区域防突措施的预抽达标期太长,如果把瓦斯含量降到8m3/t以下,预抽期高达20～24个月,正常的采掘接替无法进行。
(5)单纯的高压水力压裂技术作为区域防突措施有很大的缺陷。一是水力压裂技术的压裂区域不能人为控制,无法预知水力压裂的影响区域的准确范围；二是在使压裂区域产生卸压的同时,由于煤体的水平位移,会在压裂影响区域之外形成应力升高区或者应力集中区。防突存在盲目性。
本研究的主要针对上述问题,对深孔钻进和孔间煤体压裂卸压增透两个关键技术进行研究。
一、顺层钻孔深孔钻进方面：
实际打钻中,钻孔排出的钻屑远远大于钻孔的理论计算排渣量。在打钻的过程中,由于地应力、瓦斯应力的作用,在钻孔的周围会形成塑性变形区,而大量喷出瓦斯和煤粉,则是一种孔内动力现象。主要表现为塌孔、喷孔和卡钻等。塌孔是在地应力、瓦斯应力的作用下,加上煤质松软,钻孔孔壁经常出现垮塌现象。由于地应力集中、瓦斯应力高,加上煤体松软,钻孔钻进时极易发生喷孔,甚至发生煤与瓦斯突出,伴随着钻孔的钻进喷出大量的瓦斯和煤粉。由于喷孔主要发生在孔底或孔底附近,喷孔极易形成“孔穴”,使钻头失去钻孔壁的约束,形成钻头“扫孔”现象,孔穴越来越大,直至钻孔报废；喷孔还会造成后部钻孔壁应力增加,变形加剧,形成卡住钻杆等现象。卡钻是与喷孔有直接联系且随之发生的一种现象,喷孔发生造成孔壁变形,加上孔内煤粉的堆积,将钻杆和钻头箍紧。
1.顺层预抽钻孔施钻期间孔内瓦斯流动状态
钻孔施钻过程中,瓦斯流动和涌出的形式是不同的。从孔底到孔口的瓦斯流动状态分为三类：即球向不稳定流动、径向不稳定流动、径向稳定流动。
由于煤层深部煤层处于原岩应力状态,钻孔孔底在不断向煤体深部钻进延伸,钻头持续切割煤体,在钻孔孔底孔壁很难在短时间内形成稳定的塑性区,塑性区很薄,甚至近似为0。对于严重的突出煤层来说,瓦斯含量高、压力大,煤层透气性差、瓦斯解吸快,高压瓦斯和地应力联手,共同作用在钻孔孔底薄壁上。孔底的瓦斯球向不稳定流动致使孔壁煤体的层状剥落,然后不断向煤体深部扩展,形成瓦斯喷孔、塌孔,有的还会发展成为钻孔内煤与瓦斯突出。因此,球向不稳定流动段是影响钻孔成孔的最重要因素。
2、孔内高压理论的提出
有效遏制打钻时孔底的异常瓦斯涌出的动力现象,使球向不稳定涌出削弱后移,使径向不稳定段长度延长,是提高顺层钻孔打钻深度重要的途径。由达西定律可知,钻孔瓦斯涌出的动力,就是煤层原始瓦斯压力(P0),和孔内气体压力(p1)之压力差,如果提高施钻时空压机供风的压力,通过优化钻孔、钻具的参数,在钻孔孔底附近形成一个高气压环境,就会降低煤层内原始瓦斯压力(P0)和钻孔内气体压力(p1)之间压力差,孔底煤体吸附瓦斯急剧解吸并涌入钻孔孔底的猛烈程度就会减弱,孔底孔壁就能削弱和减少层状式剥落,钻孔持续钻进,孔底持续延伸,瓦斯的球形不稳定涌出形式,变为涌出相对不剧烈的径向不稳定流出,拉长了径向不稳定流动段的长度。瓦斯压力梯度变小,孔壁就能保持稳定,从而提高钻孔施钻深度。
3.施钻参数的选择
孔底压力决定了打钻时的排渣能力,孔底风压把煤屑加速到一定的速度,并在钻孔内搬运排出孔外。从p=△Pa+△Psac+△Ps+P0可以看出,孔底压力p越大,则△Pa、△尸Psac、△Ps就越大,排渣能力则越强。
而p=P-△Pt-△Pz即孔底压力决定于空压机提供的管道内压力,以及空气在钻杆内的阻力损失△Pz、压缩空气通过钻头的局部阻力△Pt
所以,要在钻孔直径一定的情况下,在保证排屑通道断面的前提下,缩小钻孔与钻杆之间的空间,提高钻孔内的风速则能提高搬运能力。提高空压机输出管道内的风压,增加钻杆内径减小风阻,改善钻头出风形式,降低局部阻力,就能确保孔底风压。
根据焦作矿区多年的实践,选择钻孔孔径为89mm；优化钻孔直径与钻杆直径比。选择直径73mm钻杆。根据焦作矿区原始瓦斯压力,考虑压缩空气使用的安全,合理风压选择为0.7-0.8Mpa之间。
4、钻具(1)二次扩孔钻头钻头(专利号：ZL201020124318.8)
钻头钻径越大,孔底的球向不均衡瓦斯涌出就越剧烈；钻径增大,孔壁的支撑能力则会减低。反之,小直径钻头对孔底喷孔的诱导越小,成孔更容易。基于这个原理,提出了二次扩孔分次卸压的概念。该钻头由两部分组成,前端为43mm小直径钻头,后部为89mm钻头,两者距离800-1000mm,前方的小直径钻头施工小直径钻孔,释放瓦斯压力,在小直径钻孔的周围形成应力梯度；然后由后部的扩孔钻头,将钻孔扩大89mmm直径。
(2)等直径钻杆(专利号：ZL201020124316.9)
“等直径钻杆”是在光面钻杆上焊接钻翼,排渣通道位于钻翼之间,钻杆旋转搅动钻孔里沉积的煤尘并被压风吹出,解决了光面钻杆钻屑沉积,无法排出摩擦生热的问题,同时,“等直径钻杆”直径与钻头直径基本一致,使钻杆钻头旋转、切割更稳定,也解决了钻孔的定向问题。
4.现场试验。本研究先后在焦煤集团公司古汉山矿、中泰矿业有限公司进行试验。古汉山矿现场试验自2009年7月开始,到2009年10月现场试验基本结束,共施工上下向钻孔493个,钻孔深度最低深度103米(个别其他原因失败钻孔未计),最深钻孔达到135米,平均深度米118米。中泰公司现场试验自2010年11月开始试验,到2011年2月结束,施钻深度由平均34米,提高到孔深超过90米孔数占72.8%；九里山矿16采区多个采掘地点钻进深度均能达到130m以上。为了使孔间煤体压裂试验更准确,在16161运输巷试验现场设计孔深为120米。
二、孔间煤体压裂卸压增透方面
孔间煤体水力压裂技术的提出是基于对煤与瓦斯突出机理的分析,煤与瓦斯突出是地应力、瓦斯应力以及煤体结构综合作用的结果,实施区域防突措施应当着眼上述三个方面消突。针对突出煤层透气性差,顺层钻孔预抽区段煤层瓦斯区域防突措施工程量大、预抽达标期长、削减地应力构造应力乏力的缺陷,孔间煤体水力压裂技术使煤体固有裂隙扩张的同时,使压裂煤体向自由孔形成的自由面扩张,卸压增透,煤体的塑性增加。孔间煤体水力压裂分以下几个步骤：
1.按理论计算的孔间距施工顺层钻孔,注水压裂孔、自由孔交替布置；
2.对自由孔进行冲孔,扩大等效直径。方法是：自由孔施钻完毕,对孔口段10米扩孔,采用内径l00mm的PVC管用聚氨酯进行封孔；更换水力冲孔钻头钻杆,对自由孔进行水力冲孔；
3.采用注浆封孔工艺,对注水孔进行注水泥浆封孔,封孔长度18米；
4.通过注水孔对孔间煤体实施高压水力压裂；
5.压裂以后,将所有压裂孔、自由孔联网抽放。
孔间煤体水力压裂技术研究分如下几个方面：
1.通过对国内外水力压裂技术的研究现状、研究动向和进展的充分调研,理论分析、计算机数值模拟、现场试验、综合分析相结合的方法进行研究。
2.孔间煤体压裂中煤体破坏,是高压水在钻孔壁造成张拉,继而产生裂缝,高压水充满并支撑裂缝,并使裂缝尖端不断劈裂。持续高压注水,高压水克服煤体内部摩擦力,迫使煤体逐渐向自由孔方向产生位移。首先产生Ⅰ型(张开型)裂纹；然后,克服煤层之间的摩擦力和凝聚力,产生Ⅱ型(滑开型)裂纹；最后,煤体部分或整体向自由端移动,应力得到释放。
理论分析得到钻孔周围起始开裂压力为：Pb=0.29σ1+To+Po+Pc。
维持裂缝扩展的注水压力,
3.根据九里山矿上覆盖岩层垂直应力及试验工作面煤层的泊松比,计算孔间煤体压裂的注水压力P应大于14.78MPa,但低于20Mpa。根据焦作矿区水力冲孔等效直径,计算等效断面为0.6079m2。借鉴淮南保护层开采被保护层变形量4%o,透气性系数增加300倍的经验数据,按孔间煤体变形量4‰计算,孔间距不应超过10.855m。考虑一定的系数,孔间距取6m。
4.孔间煤体处于三向不对称受力状态,垂直方向受到垂直应力σY,水平方向受到侧向应力σx及σz,工作面巷道一侧处于不受力状态,注水孔径向表面及孔底则承受水压力。对煤的力学性质进行假设分析,假设工作面前方煤体是均质、连续和各项同性的；假设煤体是线弹性体,遵循虎克定律；假设煤体只在地应力、水压力作用下变化,忽略瓦斯压力的作用,且不考虑应力、瓦斯压力、水的耦合作用。据上述分析建立了孔间煤体压裂的数值模拟力学模型。
5.采用RFPA2D数值分析软件对低透气性煤层进行水力压裂数值分析,模拟水力压裂的过程,证实孔间煤体压裂卸压程度、透气性系数增加远高于没有自由面的高压水力压裂。孔间煤体压裂能够有效地释放煤体内积聚的潜能,应力集中峰值降低,卸压增透消突效果明显。
6.现场试验选择在焦煤集团公司九里山矿,该矿为煤与瓦斯突出危险矿井。瓦斯绝对涌出量为48.53m3/min,相对瓦斯涌出量为24.17m3/t。煤层瓦斯压力均在0.75mpa以上,最高达2.08mpa,煤层瓦斯含量22.05m3/t。该矿建矿以来共发生煤与瓦斯突出65次,突出规模最大的一次发生在2011年10月27日的16031回风巷突出事故,突出煤量3246t,涌出瓦斯量29.12万m3。试验地点位于16161运输巷,该巷道沿煤层顶板布置,净断面11.04m2,采用锚网加预应力锚索支护方式。采用压入式通风,2×30KW的对旋式局部通风机通风。实际工作风量为550m3/min。布置试验钻孔19个,设计孔深120米,孔间距6米,其中1、3、5、7、9、11、13、15、17、19为自由孔,2、4、6、8、10、12、14、16、18为注水孔。试验区段走向长108米,倾斜宽120米。7.现场试验结果：2012年2月15日至3月8日顺层钻孔施钻、冲孔；2月18日压裂结束后带抽,至8月26日,累计抽放瓦斯量1820943.7m3,抽采率达67.8%,瓦斯含量降至6.91m3/t。实测煤层透气性系数增加420倍。与14121准备工作面(里段)相比(抽采达标评判报告)：煤炭储量25.58万t,瓦斯储量为438.95万m3。工作面共有抽采钻孔949个,合计孔深83239m,自2010年5月到2012年3月,抽采瓦斯量248.36万m3,计算煤层残余瓦斯含量为7.45m3/t。与16161运输巷掘进时采用煤巷密集钻孔区段预抽相比：评价区域内的原始瓦斯含量为21.46m3/t、平均煤厚为7m、煤炭储量2.95万t、瓦斯储量63.3万m3,钻孔总长度9687m,开抽时间为2011年3月1日,累计抽采时间6个月,瓦斯累计抽采量为32.2万m,瓦斯抽采率50.8%,残余瓦斯含量10.5m3/t。由此可见,孔间水力压裂技术优势明显。
8.现场试验时,随着注水孔注水压力的升高,孔间煤体进入裂隙扩展阶段以后,临近的自由孔有大量的瓦斯涌出。事实证明高压注水对煤体瓦斯的驱离作用、对吸附瓦斯的置换作用的存在。水分子的分子结构更适合吸附,水与C02、N2等气体相比,安全性更高。驱离或置换瓦斯的机理有待于我们进一步进行研究。
本课题的研究,解决了长期困扰单一突出煤层矿井的防突问题,使顺层钻孔预抽区段煤层瓦斯区域防突措施的应用更加灵活,工程量更低、抽采达标时间更短。将会进一步增强措施的可靠性,降低防突成本,彻底扭转突出矿井的经营困局。
Outburst mine with low permeability and soft and single seam, regional coal, gas outburst prevention and control have been a problem. For gas pre-drainage measure project amount is large, high cost, long time, poor effect, coal and gas outburst accident is difficult to stop and guarantee the safety in production. Through the study on the bedding of drilling hole mechanism research, the paper puts forward the theory named natural drilling and deep-hole boring " hole high pressure"; The study increases boring depth for the bedding drilling in soft coal seam with low air permeability and solves problem which gas regional outburst prevention measures cannot cover a section for the bedding hole pre-pumping section coal seam. Through the technology research on holes between the coal fracturing, computer simulation, field test, stress release of regional coal body, coal gas permeability increase, this study improves gas drainage rate, shortens the extraction time. The study opens up a new road with similar effects to mining protection layer for a single low permeability and soft coal seam with outburst.
Because of its adaptation to single outburst coal mine site conditions,regional outburst prevention measures based on Bedding hole pre pumping gas has total cost low, flexible arrangement, more apparent effect, convenient drilling construction.It was listed as the priority choice of measures in outburst prevention provisions. However, this regional outburst prevention measures has not been effective used. Following problems are reasons:
(1) Due to the single outburst coal seam poor permeability, low intensity, big gas pressure, severe nozzle hole and collapse hole, the drilling depth of not more than80meters, down the hole depth not more than60meters. Borehole coverage can not achieve a section.
(3) Hole density based on Bedding pre-draining hole density is a dilemma. Large borehole spacing affects gas drainage and regional outburst elimination; Dense borehole layout close to or through the adjacent borehole gas jet area will cause drilling deviation and even discharge the borehole pressure air from adjacent the borehole by the drilling of coal body around the uneven stress.
(3) Draining measures Only by natural drilling to eliminate stress, in tectonic stress concentrated area,its effect is not ideal. Crustal stress and structure stress in concentration zone effect coal seam permeability, so taking drainage measures will not still prominent accidents.
(4)There are great defects for a simple high pressure hydraulic fracturing technology as regional outburst prevention measures. Firstly, hydraulic fracturing area can not be controlled artificially, unpredictable fracturing effect region of accurate range. Secondly, in the fracturing area to produce a pressure relief at the same time, as a result of coal body in the fracturing effect of horizontal displacement, there will be high stress concentration zone out of the fracturing effect area. Blindness exists in outburst prevention.
In view of the above questions, this paper begins research about deep holes drilling and hole of coal body fracturing pressure relief in two key aspects.
The first aspect:deep hole drilling in the form of the bedding drilling
In the actual drilling, drilling cuttings from drilling is far greater than the theoretical calculation of the slag amount. In the drilling process, as a result of ground stress, gas stress effect, it forms the plastic deformation zone around a borehole, and a large number of discharge gas and pulverized coal, is a kind of dynamic phenomenon in the hole. The main manifestations are holes collapse, hole drilling, card and so on. Hole collapse affected by ground stress, gas stress, and soft coal, the phenomenon of the collapse will appear on the wall of the hole. Jet hole belongs to dynamic phenomenon in the drilling similar to the coal and gas outburst which is mainly affected by high-pressure gas, stress concentration and soft coal and other factors. Along with the borehole drilling it will spew gas and pulverized coal. Because the jet hole mainly occurs at the bottom of the hole or holes near the bottom, spray hole is very easy to form the "Cavity", which causes the drill bit to lose constraint by holes wall and sweep hole. The Hole will be bigger and bigger until drilling hole is scrapped. Jet holes will cause the stress increases, deformation aggravates and get drill pipe stuck. Sticking and jet orifice has direct contact. Spray hole deforms the hole. With coal accumulation, the drill pipe and the drill bit will be hooped.
1. Gas flow state during drilling hole by bedding pre-draining borehole. The form of gas flow and emission is different in the boring process. From the bottom of the hole to the orifice of the gas flowing state is divided into three categories:namely the ball to the unstable flow, radial unstable flow and radial stable flow.
Due to the deep coal seam in the original rock stress state, borehole bottom in the coal body extending to deep coal, drill bit cutting coal Continuous, it is difficult to form a stable plastic zone in hole bottom and hole wall in a short period of time. Plastic zone is very thin, or even approximate to0. For serious outburst coal seam, with high gas content, large pressure, low permeability and fast gas adsorption and desorption, interaction of high pressure gas and stress is on the thin wall of the drilling holes bottom. Gas spherical flow in hole bottom causes the hole wall to exfoliate, and then develops to deep coal Continuously, so spray hole, hole collapse will develop into coal and gas outburst in the borehole. Therefore, the unstable spherical flow is the most important factor of drilling a hole into a hole.
2. the hole pressure theory
When drilling holes and artificially elongating length of radial unstable flow, curbing abnormal gas dynamic phenomenon effectively in the borehole bottom is an important way to improve borehole depth as pre-draining gas in the coal seam. According to Darcy's law, power source of the gas flow in coal seams is caused by the pressure differential with the original gas pressure of P0, and pressure P1in a drilled hole. If we artificially create a high pressure environment in the drilled hole, Pressure difference between borehole pressure and the original gas decreases, adsorption desorption intensity of gas in the coal seam can reduce. With the continuous drilling borehole, gas emission becomes into radial unstable emission. The gas pressure becomes slow gradually so as to ensure the quality of drilling hole.
3. the application of drilling parameters
Some ways would be used to improve pressure of pre-draining borehole gas in the coal seam to adapt to technology and the requirements of high voltage for drilling a hole, namely, increasing working pressure of air compressor and flow rate of compressed air, reducing pressure loss in the pipeline, optimizing the proportion of boring hole to diameter of drilling-pipe, increasing the diameter of the drill-pipe, reducing the compressed air flow resistance of drilling-pipe, Properly reducing the cross section of discharge channel in the drilling-pipe, Increasing wind pressure and speed of discharge channel.
According to practice of many years in the Jiaozuo mining area, diameter of the hole is made89mm, diameter ratio of a borehole and drilling-pipe is optimized and the diameter73mm of a drilling-pipe is selected. According to original gas pressure of the Jiaozuo mining area, considering safety of the use of compressed air reasonable air pressure is selected for0.7-0.8Mpa
4. drilling tools
(1) Reaming bits (Patent number:ZL201020124318.8)
The bigger is drill diameter, the more intense is the uneven gas emission from of the hole bottom; conversely, the smaller drilling-bit diameter is the smaller Influence drilling-bits cause on the bottom of the hole orifice. Based on this principle, the concept is put forward namely a second counter bore and multiple pressure relief. The drilling-bit is composed of two parts, the distance between two part is800-1000mm. namely, the front end for43mm-diameter small drilling-bit and the rear89mm. The small diameter-drill constructs small-diameter bores, gas pressure is released and the stress gradient is formed around in small diameter hole. Then the rear drilling-bit develops the bore to89mm diameter.
The "Equal diameter drill" is welded the drill wing to the smooth rod and discharge channel is located between the drill wing. Drill rod rotating stirs deposited dust in the drilling hole and presses the wind out. Eliminating the drill-cuttings deposition on the smooth surface and discharging friction heat". Diameter of drill-pipe with equal diameter is basically the same to the diameter of the drill bit which also solves the problem of directional drilling.
4. field tests.
It has been tested about this study in Guhanshan Coal Mine and China and Thailand Mining Company Limited in Coking Coal Group. The field test has been done from2009July to2009October in Guhanshan Coal Mine. A total construction of downward are493holes, hole depth of minimum depth of103meters (the other reason for the failure of individual drilling not counted)the deepest drilling to135meters, average depth of118meters. The field test has been done in China and Thailand Mining Company Limited from2010November to2011February test. The boring depth by a mean is34meters, up to72.8%holes more than90meters deep. The drilling depth all can reach above130metres in sixteenth mining area of Jiuli Hill Coal Mine. In order to make the coal crushing test more accurate between the holes, the hole depth designed is120meters in test site of the16161th transport tunnel.
The second aspect:the coal in pore space fractured under pressure and release
pressure to increase permeability
The hydraulic fracturing technology for the coal in pore space was discovered based on the analysis of theory for coal and gas outburst. The coal and gas outburst happens under the comprehensive effect of ground stress, gas stress and coal structure, on which should be focused when implementation regional outburst prevention measure. Take care of the poor permeability of outburst coal seam, the huge project and the long time limited of outburst prevention measure used in coal and gas areas, and the bad cutting down ground stress, The hydraulic fracturing technology for the coal in pore space, at the time coal natural fissure expanding, makes the fractured coal expand to the free surface formed by the free holes, unloads the ground stress and increases the plasticity
The hydraulic fracturing technology contains the following steps:1. According the theoretical calculated hole space to construct, drilling along the coal seams, the injection water holes and free holes constructed alternately.
2. Take hole punching to free holes, expand the equivalent diameter. The methods are:after drilling the free holes, punch the orifice for10meters, sealing used the polyurethane with diameter100mm PVC pipes; change the drill bits and drill pipes with hydraulic drill to punch the free hole.
3. Using the grouting hole technology to seal the holes, injection slurry18m length.
4. Taking high pressure hydraulic to fracture the coal through injection water holes.
5. Network all fractured holes and free holes to emission gas after fractured the coal.
Researching hydraulic fracturing technology divides into the following aspects:
1. The hydraulic fracturing technology should be researched by full investigation the present situation, research way and progress in home and abroad, theoretical analysis, numerical simulation, field test and comprehensive analysis.
2. During be fractured, the coal destroyed by the high pressure water tensile around the borehole to form fissures, the high pressure water propped fracture, which make the fissures tips continue to prop, expand and extend. With the further injecting water, overcome the friction between coal layers, crush the coal to free holes. First, produce Ⅰ model (open type) fissures; then overcome the friction and cohesion between the seams, form Ⅱ model (sliding type) fissures; at last, part or whole coal body move to free ends, and stress release. The initial cracking pressure analyzed by theories is:Pb=0.29σ1+T0+P0+Pc。
The injection pressure for Maintenance the crack is:
3. According the vertical stress of rock stratum covered on the Jiuli Hill Mine, and the Poisson's ratio of the coal seam in test areas, the injection water pressure for the coal fractured in pore space is more than14.78MPa, and less than20Mpa. According to Jiaozuo mining hydraulic hole equivalent diameter, calculating the equivalent section is0.6079m2. Draw lessons from Huainan Mining, mining the protective layer leads to protected layers deform4‰, the permeability coefficient increases300times, the coal between holes deform4‰, the space between holes is not exceed10.855m, given a certain coefficient, the space between holes is6m.
4. The coal in hole space is in the asymmetric stress state, the vertical stress is σY, the horizontal direction is x and z, one side of the coal tunnel is not stressed, injection water holes are stressed by water in warp direction and bottom. Assumed analysis the coal dynamics properties, the coal in front of the working face is homogeneous, continuous, isotropic, assumed that the coal is linear elastic, followed Hooke's law, the coal body is changed only by ground and water stress, ignore the gas pressure, don't given the effect of stress, gas pressure, water coupling. On the basis of above analysis, establish the numerical simulation dynamics model.
5. Take repeated trial to this model by software RFPA2D, contrast the actual and simulated parameters of stress in coal, displacement, elastic potential and so on. Determine the ultimate model, calculate the other models under different injection water parameters.
6. Filed test is carried in Jiaozuo Coal Group Jiuli Hill Mine, which is coal and gas outburst mine. The absolute gas outburst rate is48.53m3/min, the relative gas outburst rate is24.17m3/t, the gas pressure in coal is average in above of0.75MPa, sometimes is up to2.08MPa, the gas storage in coal is22.05m3/t. Since the mine is built, the mine has happened65times coal and gas outburst, the highest occurred in October27,2011, in the16031returned air alley, the coal outburst quantity was3246t, the gas was291200m3.
The field test site was in16161transport tunnel, which was layout along the roof of coal seam, cross sectional11.04m2, supported by anchor net and anchor cable. This tunnel used the forced ventilation, installed two2x30KW counter local fans, one work the other spare. The actual wind flow was550m3/min. Fixed test19drills, of which1,3,5,7,9,11,13,15,17,19,4,2were free holes,6,8,10,12,14,16,18were water injection holes, designed the hole120m deep, hole space6m., This test section was108m long, tilt wide120m.
7. The field test results:from February15,2012to March8th, drilled along the layers, punched, February18th finished the fracturing and to extract the gas, to August26th, the total drainage gas was1820943.7m3, the extraction rate was67.8%, the gas content was drop to6.91m3/t. the actual test coal permeability coefficient was increase420times
Compared to preparatory work surface named the14121th area (in)(with the report of extraction to standard):coal reserve is255800T, gas content is4389500m3. The work surface extraction drills were949, the total holes' depth was83239m. From May2010to March2012, extraction of gas volume was2483600m3, calculated the residual gas content was7.45m3/t.
Compared with16161transport tunnel during pre-extract by dense drilling in coal tunnel: the regional gas content in evaluated area was21.46m3/t, average coal seam thickness was7m, coal reserves was29500T, gas reserves was633000m3, total drills'length was9687m, started to extract gas in March1st,2011, accumulation pumping capacity was322000m3, The gas pumping rate was50.8%, the residual gas content was10.5m3/t.
From the above comparative analysis, the hydraulic fracturing technology has obvious advantage.
8. During the field tests, along with injection water pressure increases, the coal body begins to crack, a large number of gas emitted around the free holes. The fact have proved that the effect of high pressure injection water to dispel the gas in coal, displace the gas adsorbed on coal exists. The water molecular structure is more suitable to absorption than gas, and has higher security contrast to CO2, N2and so on. The theory of dispelling and displacement of gas needs to further study.
This research topic, has resolved the long term problem that single coal outburst mine how to prevent outburst, and the prevention measures used in gas content areas during drilling along coal layers is more flexible, less engineering, and drop the time to standard. This method will enhance the reliability of preventing outburst, and reduce the cost of preventing outburst, change the management predicament of outburst mines.
引文
[1]辛新平,魏国营,李学臣等.严重突出煤层快速掘进防突技术研究鉴定资料.焦作：焦作煤业集团有限责任公司科学技术研究所.2002.12.
[2]国家安全生产监督管理局网(http://www.chinacoal-safety.gov.cn/aqtj.htm)
[3]O.И切耳诺夫,E.C罗赞采夫,瓦斯突出危险煤层井田的准备(宋世钊,于不凡译).北京：煤炭工业出版社,1980.
[4]茹尔托夫.油层水力压裂,北京：中国工业出版社,1964。50-60。
[5]G·豪瓦尔德.油层水力压裂原理,北京：石油工业出版社,1980。
[6]王鸿勋.水力压裂原理,北京,石油工业出版社,1987,3。
[7]Morales.H[英].澳大利亚鲍恩煤田水力致裂特性的分析,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 3
[8]Mrak.G[英].昆士兰日耳曼煤层钻孔水力致裂试验,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 3
[9]Leibowitz[英].煤层透气性方向相关及其对甲烷工作面的影响,Ventilation Congress,1992,10.
[10]Harpalani[英].瓦斯抽放对煤层孔隙率和渗透性的影响,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 11
[11]乌效鸣,屠厚泽.煤层水力压裂典型裂缝形态分析与基本尺寸确定,中国地质大学学报,12(5)：40-50.
[12]阳友奎,肖长富,邱贤德等,水力压裂裂缝形态与缝内压力分布,重庆大学学报,1995,2：30一36。
[13]陈勉,陈治喜等.三维弯曲水力压裂水压裂缝力学模型及计算方法,石油大学学报,1995,7：23-26。
[14]雷群.浅谈高能气体压裂与水力压裂联作技术,钻采工艺,1999,22(4),17-18。
[15]曲展,任书全.水力压裂施工停泵卸压后裂缝闭合压密数学模型初探,西南石油学院学报,18(1),81-82。
[16]防治煤与瓦斯突出规定,国家安全生产监督管理局长令第19号,北京：2008.
[17]河南省焦作市方庄煤矿,煤炭科学研究总院抚顺分院.方庄煤矿煤与瓦斯突出防治技术研究,研究报告,焦作：河南焦作方庄煤矿及煤炭科学研究总院抚顺分院,1995.3,33-34.
[18]周世宁,林柏泉.煤层瓦斯赋存与流动理论.煤炭工业出版社,1999.
[19]李世奇,杜慧琴Maple计算机代数系统应用及程序设计.重庆：重庆大学出版社,1999
[20]洪维恩.数学魔法师Maple6北京：人民邮电出版社,2001。
[21]刘辉,李海Maple符号处理及应用.北京：国防工业出版社,2001
[22]张智星Matlab程序设计与应用.北京：清华大学出版社,2002,12
[23]王炳武MATLAB5.3实用教程.北京：中国水电出版社,2000,7
[24]张明哲Matlab6.5入门与精通,北京：清华大学出版社,2003,2.
[25]Misra.J.B.Use of uzzy settheory forlevel-Istudiesin, probabilistic crisk assessment Fuzzys et and Systems.1990,37:106-125.
[26]白新华.水力掏槽快速消突技术研究,河南理工大学硕士论文.2009,04-,01.
[27]许彦鹏.水力挤出快速消突措施关键技术研究,《河南理工大学硕士论文》,2007,04,01
[28]刘国俊.淮南矿区水力冲孔技术参数优化及效果考察研究.《河南理工大学硕士论文》.2011,04,01
[29]王国强.实用工程数值模拟技术及其在ANSYS上的实践.西安：西北工业大学出版社.2001,1.
[30]陈火红,Marc有限元实例分析教程.北京：机械工业出版社,2002,4
[31]于不凡.煤和瓦斯突出机理.北京：煤炭工业出版社.1985,8.
[32]申晋,赵阳升,段康廉.低渗透煤岩体水力压裂的数值模拟,煤炭学报,32(6),58-59.
[33]蔡成功.煤与瓦斯突出三维模拟理论及试验研究.见(1n)：王兆丰等.瓦斯地质研究与应用(论文集).北京：煤炭工业出版社,2003.113。
[34]白明华,刘洪彬.工程弹性力学基础.北京：机械工业出版社.1996,4.5-6.
[35]文光才.无线电波透视煤层突出危险性机理的研究[博士论文].北京：中国矿业大学,2003,5,66-68.
[36]贾喜荣.矿山岩石力学.北京：煤炭工业出版社,1997.9,80-82.
[37]林柏泉.深孔控制卸压爆破及其防突作用机理的试验研究.阜新矿业学院学报,1995,14(3)：21-22。
[38]张铁钢.矿井瓦斯综合治理技术.北京：煤炭工业出版社,2001.3.
[39]张明杰,马耕.鹤壁矿区煤与瓦斯突出控制因素及防治技术
[40]谢文兵等.数值模拟在工程实践中的应用分析.矿山压力与顶板支护.1999,3.
[41]郭大立.水力压裂优化设计方法研究.西南石油学院学报.2001.1
[42]煤矿安全规程.国家安全生产监督管理总局,2007.1
[43]孙和应,常松岭.矿井瓦斯防治技术.北京：煤炭工业出版社,2009
[44]李运宏.松软煤层抽采钻进关键技术研究.煤,2010,9.56-75
[45]孙玉宁,王永龙,翟新献,王振峰.松软突出煤层钻进困难的原因分析.煤炭学报,2012.1
[46]郭奉贤,赵发军,杨运峰,王念红.松软煤层深孔钻进工艺实践.中州煤炭.2009.12
[47]琚宏兴,冯卫.影响煤层深孔打钻的原因分析和防范措施.山东煤炭科技,2008.3
[48]王兆丰,范迎春,李世生.水力冲孔技术在松软低透突出煤层中的应用.煤炭科学技术,2012,2.52-55
[49]刘明举,崔凯,刘彦伟,邓奇根,刘英振.深部低透气性煤层水力冲孔措施防突机理分析.煤炭科学技术.2012,2.45-48
[50]刘志强.水力挤出措施机理研究.河南理工大学硕士毕业论文,2007
[51]刘军.水力挤出快速消突措施合理注水压力研究.河南理工大学硕士毕业论文,2007
[52]肖知国,王兆丰,陈立伟,杨宏民.煤层高压注水防治煤与瓦斯突出效果考察及机理 分析.河南理工大学学报,2010.6
[53]肖知国,王兆丰.煤层注水防治煤与瓦斯突出机理的研究现状与进展.中国安全科学学报,2009.10
[54]袁亮.松软低透气性煤层群瓦斯抽采理论与技术.北京：煤炭工业出版社,2004
[55]唐春安主编.岩石破裂过程数值试验[M].长春：吉林大学出版社,2002年.
[56]杨天鸿等.水压致裂过程分析的数值试验方法[J].力学与实践,2001,23(5)：51-54.
[57]徐涛,唐春安,张永斌等.单轴压缩下脆性岩石变形破坏的理论试验和数值模拟[J].东北大学学报,2003,24(1)：87-90.
[58]任培良.水力冲孔卸压增透技术的研究与应用.河南理工大学硕士论文.2009,04,12.
[59]林府进,孙东玲,董钢锋.顺层长钻孔风力排渣成孔技术.矿业安全与环保.2001,04,10
[60]肖知国.煤层注水抑制瓦斯解吸效应实验研究与应用.河南理工大学博士论文.2010,10,01.
[61]苏现波,刘晓,倪小明等.煤矿井下钻孔水力压裂增透抽采瓦斯工艺.河南理工大学.2009,04,08
[62]Wang Zhaofeng, Liu Jun, Li Zhiqiang. Study on the Mechanism for Prevention of Outburst by Hydraulic Extrusion Measure Based on the Numerical Simulation. [In]Progress in Safety and Technology.2004,10:2159-2163
[63]Mrak.G[英]. Characteristic test of hydraulic crush on nordic coal seam.Symposium On Coalbed Methane Research and Development in Ausralia,1992.3
[64]潘辉.水力挤出防突机理及注水参数优化研究.河南理工大学硕士论文.2007,04,01
[65]罗文柯,上覆巨厚火成岩下煤与瓦斯突出灾害危险性评估与防治对策研究.中南大学博士论文.2010,12,01.
[66]陈忠海.煤与瓦斯突出的流变机理.煤炭技术.2005,12,10.
[67]梁冰,章梦涛,潘一山等.瓦斯对煤的力学性质及力学响应影响的试验研究.岩土工程学报.1995,10,02.
[68]徐阿猛.深孔预裂爆破抽放瓦斯的研究.重庆大学硕士论文.2007,03,01
[69]贺媛.高瓦斯矿井炮掘工作面瓦斯涌出规律的研究.内蒙古科技大学硕士论文.2010,05,25.
[70]陈雷.低透气性高瓦斯煤层水力冲孔防突技术研究.安徽理工大学硕士论文.2010,06,01.
[71]胡鹏.煤层瓦斯抽放钻孔单向流动负压分布规律的研究.河南理工大学硕士论文.2009,04,01.
[72]Bhamidipati B.etal. Nonlinear Programming Technique for Analysis of Mine Ventilation Networks. Transaction of the Institution of Mining and Metallurgy[J]. section A:Mine Industry. Vol,95,Januayr/April19 96,12-30
[73]. StefankoR.etal.Mine Ventilation Network Analysis [M].Transactions AIME-SME, Vo 1.2 52,1972,81-90
[74]. MinskyM,PapetrS.Perceptron.MITP ress,19 69,62-71.
[75]Wang YJ. Solving Mine Ventilation Networks with Fixed and Non. fixed Bra nc he s(J).MiningE ngineering.19 90,12:42-43
[76]. Ueng T.H. etal. Analysis of Mine Ventilation Networks U sing N online ear Programming Techniques[J].International Journal of M in engineering. 1984,4-11,
[77]J. Wang. Safety analysis and synthesis using fuzzy sets and evidential reasoning. Reliability Engineering and Safety.1995,47:103-108.
[78]Leinming. Xing. David Okrent. Theuse of neural network and a prototype expetrsystem in BWRANTWS accidents diagnosis. Reliability Engineering and Safety.1994,44:105-116
[79]Leibowitz.[英].Coal seam permeability and its affect to working face.Ventilation Congress,1992.10
[80]Harpalani.[英].Affect to coal seam permeability and penetrability of gas extraction.Symposium On Coalbed Methane Reseach and Development in Ausralia,1992.11
[81]Morales.H[英]. Characteristic analysis on hydraulic crush in Ausralia BoEn coal-field. Symposium On Coalbed Methane Research and Development in Ausralia,1992.3
[2]国家安全生产监督管理局网(http://www.chinacoal-safety.gov.cn/aqtj.htm)
[3]O.И切耳诺夫,E.C罗赞采夫,瓦斯突出危险煤层井田的准备(宋世钊,于不凡译).北京：煤炭工业出版社,1980.
[4]茹尔托夫.油层水力压裂,北京：中国工业出版社,1964。50-60。
[5]G·豪瓦尔德.油层水力压裂原理,北京：石油工业出版社,1980。
[6]王鸿勋.水力压裂原理,北京,石油工业出版社,1987,3。
[7]Morales.H[英].澳大利亚鲍恩煤田水力致裂特性的分析,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 3
[8]Mrak.G[英].昆士兰日耳曼煤层钻孔水力致裂试验,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 3
[9]Leibowitz[英].煤层透气性方向相关及其对甲烷工作面的影响,Ventilation Congress,1992,10.
[10]Harpalani[英].瓦斯抽放对煤层孔隙率和渗透性的影响,Symposium On Coalbed Methane Reseach and Development in Ausralia, 1992, 11
[11]乌效鸣,屠厚泽.煤层水力压裂典型裂缝形态分析与基本尺寸确定,中国地质大学学报,12(5)：40-50.
[12]阳友奎,肖长富,邱贤德等,水力压裂裂缝形态与缝内压力分布,重庆大学学报,1995,2：30一36。
[13]陈勉,陈治喜等.三维弯曲水力压裂水压裂缝力学模型及计算方法,石油大学学报,1995,7：23-26。
[14]雷群.浅谈高能气体压裂与水力压裂联作技术,钻采工艺,1999,22(4),17-18。
[15]曲展,任书全.水力压裂施工停泵卸压后裂缝闭合压密数学模型初探,西南石油学院学报,18(1),81-82。
[16]防治煤与瓦斯突出规定,国家安全生产监督管理局长令第19号,北京：2008.
[17]河南省焦作市方庄煤矿,煤炭科学研究总院抚顺分院.方庄煤矿煤与瓦斯突出防治技术研究,研究报告,焦作：河南焦作方庄煤矿及煤炭科学研究总院抚顺分院,1995.3,33-34.
[18]周世宁,林柏泉.煤层瓦斯赋存与流动理论.煤炭工业出版社,1999.
[19]李世奇,杜慧琴Maple计算机代数系统应用及程序设计.重庆：重庆大学出版社,1999
[20]洪维恩.数学魔法师Maple6北京：人民邮电出版社,2001。
[21]刘辉,李海Maple符号处理及应用.北京：国防工业出版社,2001
[22]张智星Matlab程序设计与应用.北京：清华大学出版社,2002,12
[23]王炳武MATLAB5.3实用教程.北京：中国水电出版社,2000,7
[24]张明哲Matlab6.5入门与精通,北京：清华大学出版社,2003,2.
[25]Misra.J.B.Use of uzzy settheory forlevel-Istudiesin, probabilistic crisk assessment Fuzzys et and Systems.1990,37:106-125.
[26]白新华.水力掏槽快速消突技术研究,河南理工大学硕士论文.2009,04-,01.
[27]许彦鹏.水力挤出快速消突措施关键技术研究,《河南理工大学硕士论文》,2007,04,01
[28]刘国俊.淮南矿区水力冲孔技术参数优化及效果考察研究.《河南理工大学硕士论文》.2011,04,01
[29]王国强.实用工程数值模拟技术及其在ANSYS上的实践.西安：西北工业大学出版社.2001,1.
[30]陈火红,Marc有限元实例分析教程.北京：机械工业出版社,2002,4
[31]于不凡.煤和瓦斯突出机理.北京：煤炭工业出版社.1985,8.
[32]申晋,赵阳升,段康廉.低渗透煤岩体水力压裂的数值模拟,煤炭学报,32(6),58-59.
[33]蔡成功.煤与瓦斯突出三维模拟理论及试验研究.见(1n)：王兆丰等.瓦斯地质研究与应用(论文集).北京：煤炭工业出版社,2003.113。
[34]白明华,刘洪彬.工程弹性力学基础.北京：机械工业出版社.1996,4.5-6.
[35]文光才.无线电波透视煤层突出危险性机理的研究[博士论文].北京：中国矿业大学,2003,5,66-68.
[36]贾喜荣.矿山岩石力学.北京：煤炭工业出版社,1997.9,80-82.
[37]林柏泉.深孔控制卸压爆破及其防突作用机理的试验研究.阜新矿业学院学报,1995,14(3)：21-22。
[38]张铁钢.矿井瓦斯综合治理技术.北京：煤炭工业出版社,2001.3.
[39]张明杰,马耕.鹤壁矿区煤与瓦斯突出控制因素及防治技术
[40]谢文兵等.数值模拟在工程实践中的应用分析.矿山压力与顶板支护.1999,3.
[41]郭大立.水力压裂优化设计方法研究.西南石油学院学报.2001.1
[42]煤矿安全规程.国家安全生产监督管理总局,2007.1
[43]孙和应,常松岭.矿井瓦斯防治技术.北京：煤炭工业出版社,2009
[44]李运宏.松软煤层抽采钻进关键技术研究.煤,2010,9.56-75
[45]孙玉宁,王永龙,翟新献,王振峰.松软突出煤层钻进困难的原因分析.煤炭学报,2012.1
[46]郭奉贤,赵发军,杨运峰,王念红.松软煤层深孔钻进工艺实践.中州煤炭.2009.12
[47]琚宏兴,冯卫.影响煤层深孔打钻的原因分析和防范措施.山东煤炭科技,2008.3
[48]王兆丰,范迎春,李世生.水力冲孔技术在松软低透突出煤层中的应用.煤炭科学技术,2012,2.52-55
[49]刘明举,崔凯,刘彦伟,邓奇根,刘英振.深部低透气性煤层水力冲孔措施防突机理分析.煤炭科学技术.2012,2.45-48
[50]刘志强.水力挤出措施机理研究.河南理工大学硕士毕业论文,2007
[51]刘军.水力挤出快速消突措施合理注水压力研究.河南理工大学硕士毕业论文,2007
[52]肖知国,王兆丰,陈立伟,杨宏民.煤层高压注水防治煤与瓦斯突出效果考察及机理 分析.河南理工大学学报,2010.6
[53]肖知国,王兆丰.煤层注水防治煤与瓦斯突出机理的研究现状与进展.中国安全科学学报,2009.10
[54]袁亮.松软低透气性煤层群瓦斯抽采理论与技术.北京：煤炭工业出版社,2004
[55]唐春安主编.岩石破裂过程数值试验[M].长春：吉林大学出版社,2002年.
[56]杨天鸿等.水压致裂过程分析的数值试验方法[J].力学与实践,2001,23(5)：51-54.
[57]徐涛,唐春安,张永斌等.单轴压缩下脆性岩石变形破坏的理论试验和数值模拟[J].东北大学学报,2003,24(1)：87-90.
[58]任培良.水力冲孔卸压增透技术的研究与应用.河南理工大学硕士论文.2009,04,12.
[59]林府进,孙东玲,董钢锋.顺层长钻孔风力排渣成孔技术.矿业安全与环保.2001,04,10
[60]肖知国.煤层注水抑制瓦斯解吸效应实验研究与应用.河南理工大学博士论文.2010,10,01.
[61]苏现波,刘晓,倪小明等.煤矿井下钻孔水力压裂增透抽采瓦斯工艺.河南理工大学.2009,04,08
[62]Wang Zhaofeng, Liu Jun, Li Zhiqiang. Study on the Mechanism for Prevention of Outburst by Hydraulic Extrusion Measure Based on the Numerical Simulation. [In]Progress in Safety and Technology.2004,10:2159-2163
[63]Mrak.G[英]. Characteristic test of hydraulic crush on nordic coal seam.Symposium On Coalbed Methane Research and Development in Ausralia,1992.3
[64]潘辉.水力挤出防突机理及注水参数优化研究.河南理工大学硕士论文.2007,04,01
[65]罗文柯,上覆巨厚火成岩下煤与瓦斯突出灾害危险性评估与防治对策研究.中南大学博士论文.2010,12,01.
[66]陈忠海.煤与瓦斯突出的流变机理.煤炭技术.2005,12,10.
[67]梁冰,章梦涛,潘一山等.瓦斯对煤的力学性质及力学响应影响的试验研究.岩土工程学报.1995,10,02.
[68]徐阿猛.深孔预裂爆破抽放瓦斯的研究.重庆大学硕士论文.2007,03,01
[69]贺媛.高瓦斯矿井炮掘工作面瓦斯涌出规律的研究.内蒙古科技大学硕士论文.2010,05,25.
[70]陈雷.低透气性高瓦斯煤层水力冲孔防突技术研究.安徽理工大学硕士论文.2010,06,01.
[71]胡鹏.煤层瓦斯抽放钻孔单向流动负压分布规律的研究.河南理工大学硕士论文.2009,04,01.
[72]Bhamidipati B.etal. Nonlinear Programming Technique for Analysis of Mine Ventilation Networks. Transaction of the Institution of Mining and Metallurgy[J]. section A:Mine Industry. Vol,95,Januayr/April19 96,12-30
[73]. StefankoR.etal.Mine Ventilation Network Analysis [M].Transactions AIME-SME, Vo 1.2 52,1972,81-90
[74]. MinskyM,PapetrS.Perceptron.MITP ress,19 69,62-71.
[75]Wang YJ. Solving Mine Ventilation Networks with Fixed and Non. fixed Bra nc he s(J).MiningE ngineering.19 90,12:42-43
[76]. Ueng T.H. etal. Analysis of Mine Ventilation Networks U sing N online ear Programming Techniques[J].International Journal of M in engineering. 1984,4-11,
[77]J. Wang. Safety analysis and synthesis using fuzzy sets and evidential reasoning. Reliability Engineering and Safety.1995,47:103-108.
[78]Leinming. Xing. David Okrent. Theuse of neural network and a prototype expetrsystem in BWRANTWS accidents diagnosis. Reliability Engineering and Safety.1994,44:105-116
[79]Leibowitz.[英].Coal seam permeability and its affect to working face.Ventilation Congress,1992.10
[80]Harpalani.[英].Affect to coal seam permeability and penetrability of gas extraction.Symposium On Coalbed Methane Reseach and Development in Ausralia,1992.11
[81]Morales.H[英]. Characteristic analysis on hydraulic crush in Ausralia BoEn coal-field. Symposium On Coalbed Methane Research and Development in Ausralia,1992.3