低温循环致裂煤体孔隙结构演化规律试验研究

发布时间：2018-05-15 02:25

本文选题：瓦斯抽采 + 冻融　；参考：《煤炭科学技术》2017年06期

【摘要】：针对我国单一低透气性煤层常规钻孔瓦斯抽采困难的问题,提出了低温循环致裂增透方法。该方法将液氮等低温介质注入煤体,实现煤体的降温冻结;之后冻结煤体从周围煤岩吸热融化,循环地注入低温流体可使煤体产生交变的冻结-融化现象,从而改变煤体的孔隙结构和渗透性。采用冻融机对饱水煤样进行了共20次循环的冻融试验,并利用核磁共振测试方法,分析了低温循环冻融作用下煤体孔隙结构特征的演化规律。研究结果表明:随着冻融次数的增加,煤样的中、大孔占比、总孔隙度、有效孔隙度和渗透率显著增加,表明多次冻融能使煤体孔隙数量增加,尺寸变大,连通增强,从而形成交织贯通的孔裂隙网络,使煤体透气性大幅增强。
[Abstract]:Aiming at the difficult problem of gas extraction by conventional drilling in single low permeability coal seam in our country, a method of low temperature circulation fracturing and antireflection is put forward. In this method, liquid nitrogen and other low-temperature media are injected into the coal body to realize the freezing and freezing of the coal body, then the frozen coal body absorbs heat from the surrounding coal and thawes, and the circulating injection of low-temperature fluid can cause the coal body to produce alternating freezing and melting phenomenon. Thus, the pore structure and permeability of coal body are changed. The freezing and thawing tests of saturated coal samples were carried out on a freeze-thaw machine for 20 cycles. The evolution of pore structure characteristics of coal body under low temperature circulation freezing and thawing was analyzed by nuclear magnetic resonance (NMR) method. The results show that: with the increase of freezing and thawing times, the percentage of large pores, total porosity, effective porosity and permeability of coal samples increase significantly, which indicates that multiple freeze-thaw energy can increase the number of pores, increase the size and increase the connectivity of coal bodies. Thus forming the interlaced network of holes and fissures, the permeability of coal body is greatly enhanced.
【作者单位】：中国矿业大学安全工程学院;煤矿瓦斯治理国家工程研究中心;
【基金】：国家自然科学基金资助项目(U1361106,51274195) 国家重大科学仪器设备开发专项资助项目(2013YQ17046309)
【分类号】：TD712.6

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