高瓦斯煤层井下穿层水力压裂强化增透技术研究

发布时间：2018-04-24 08:03

本文选题：水力压裂 + 煤与瓦斯突出　；参考：《安徽理工大学》2017年硕士论文

【摘要】：本文运用理论研究、数值模拟与现场试验的相结合的方法,将新庄孜矿C13煤层作为试验对象,考察了水力压裂的实施起到的作用。事实证实,水力压裂工作实施后,C13煤层的瓦斯浓度大幅度降低、瓦斯抽采率大大提高、透气性明显有所改善,有效的预防了煤与瓦斯突出的可能性。对水力压裂增透理论进行了研究,大直径钻孔能够使钻孔周围卸压范围增大;钻孔周围裸露的煤体大大增多;煤体内气体流动性增强,透气性大幅度改善。运用RFPA2D软件进行模拟实验,煤层起裂压力为30MPa,压裂结束后,裂隙延伸扩展长度可达到35～40m左右;按照应力的分布情况把钻孔四周的煤体可划成四个区域,从中心位置到煤体深部依次为:卸压区(0～35m);集中区(35～50m);过渡区(50～62.5m);原始应力区(62.5m)。单孔水力压裂影响范围半径可达35m;通过水力压裂的实施,煤层渗透性一定程度上得到了改善,提高了将近25倍。压裂过程中,水流量最高可达400m3/(d.m),说明煤体的渗透性显著得到改善。根据压裂区域煤层含水率的变化规律,初步判断压裂半径大于50m;根据压裂区域煤体内的瓦斯含量变化规律得知,压裂半径在30～50m之间。钻孔40m区域内,压裂效果明显,瓦斯含量显著下降,说明在压裂孔影响范围达到40m。根据压裂区域煤层含水率的变化规律,初步判断压裂半径大于50m;通过测定未压裂的煤体的瓦斯压力为4.9MPa,水力压裂过后,通过求解,瓦斯压力急剧减小,减小至1MPa;原始的透气性系数为0.032m2/MPa2·d,压裂过后,增大到0.840m2/MPa2·d,压裂效果显著,一定程度上改善了煤层的透气性。通过水力压裂现场试验,证实了数值模拟的准确性,水力压裂技术的实施可有效改善煤层的透气性,提高瓦斯抽采率,降低了煤与瓦斯的突出危险性,保证了采煤工作可以安全高效的进行。
[Abstract]:In this paper, the C13 coal seam of Xinzhuangzi Mine is taken as the test object by the method of theoretical research, numerical simulation and field test, and the effect of hydraulic fracturing is investigated. It is proved that after hydraulic fracturing, the gas concentration of coal seam C13 is greatly reduced, the gas extraction rate is greatly increased, and the permeability is obviously improved, which effectively prevents the possibility of coal and gas outburst. The anti-permeability theory of hydraulic fracturing is studied. The large diameter borehole can increase the pressure relief range around the borehole; the exposed coal body around the borehole increases greatly; the gas fluidity of coal body is enhanced and the gas permeability is greatly improved. The RFPA2D software is used to simulate the experiment. The fracture initiation pressure is 30 MPA. After fracturing, the extension length of the fracture can reach 35 ~ 40 m. According to the stress distribution, the coal body around the borehole can be divided into four areas. From the central position to the deep part of the coal body, the order is as follows: the pressure relief area is 0 ~ (35) m ~ (-1), the concentration area is 35 ~ (50) m ~ (-1), the transition area is 50 ~ 62.5 m ~ (-1), and the original stress area is 62.5 m ~ (-1). The radius of single hole hydraulic fracturing can reach 35 m.The permeability of coal seam is improved to a certain extent by hydraulic fracturing, which is nearly 25 times higher. During fracturing, the maximum water flow rate can reach 400 m3 / d. M, which indicates that the permeability of coal body has been improved significantly. According to the variation rule of water cut of coal seam in fracturing area, the fracture radius is more than 50m, and the fracture radius is between 30m and 50m according to the change rule of gas content in coal body in fracturing area. The effect of fracturing is obvious and the gas content is significantly decreased in the 40m area of borehole, which indicates that the influence range of fracturing hole is 40m. According to the variation rule of water cut of coal seam in fracturing area, the fracture radius is more than 50 m, the gas pressure of coal body without fracturing is 4.9 MPA, after hydraulic fracturing, the gas pressure decreases sharply after hydraulic fracturing. The original permeability coefficient is 0.032m2/MPa2 d, and after fracturing, it increases to 0.840m2/MPa2 d, the effect of fracturing is remarkable, and the permeability of coal seam is improved to some extent. The accuracy of numerical simulation is proved by the field test of hydraulic fracturing. The application of hydraulic fracturing technology can effectively improve the permeability of coal seam, increase the gas extraction rate and reduce the danger of coal and gas outburst. It ensures that the coal mining work can be carried out safely and efficiently.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.62

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