Investigation of enhancing coal permeability with high-temperature treatment
Investigation of enhancing coal permeability with high-temperature treatment
复制标题
高温处理提高煤透气性的研究
DOI：
10.1016/j.fuel.2020.120082
复制
发表时间：
2021-01-14
期刊：
影响因子：
7.4
通讯作者：
Chen, Zhangxing
中科院分区：
文献类型：
--
作者：
Liu, Jiang;Kang, Yili;Chen, Zhangxing
利用地层热处理提高煤的渗透率是煤层气开发的一种很有前途的方法。本文对热处理提高煤渗透率的机理进行了研究。将残留的水煤样品在氦气气氛中依次在50 ° C、100 ° C、200 ° C、400 ° C、600 ° C和800 ° C下加热。在每次热处理后测量样品的渗透性和声波速度，并计算杨氏模量和剪切模量以确定机械性能的变化。此外，通过低压N2吸附和SEM分析了孔结构和表面性质的变化。结果表明，在50-200 ℃温度范围内，本体水和层间水被脱除，减轻了水相捕集效应，增强了气体流动通道，渗透率提高了4-14倍。在400 ~ 600 ℃之间，煤样开始热解，弱化了煤的力学性能，裂缝开始产生并延伸，导致渗透率增加79-1400倍。800 ℃后，煤的表面完全热解，样品破裂，渗透率增加了20,000倍以上。FHT对煤层气储层的增产机理包括水相圈闭的缓解、煤体力学性质的弱化和燃烧导致煤体破裂，最终导致煤体分子中的C-C键和C-O键断裂，促使煤体破裂产生更多的气体流动通道。针对FHT的现场应用，分析了其优缺点。
Enhancing coal permeability with formation heat treatment (FHT) is a prospective method in coalbed methane (CBM) exploitation. Here, the mechanisms of coal permeability enhancement induce by heat treatment are investigated. Residual water coal samples were heated in a helium atmosphere at 50 degrees C, 100 degrees C, 200 degrees C, 400 degrees C, 600 degrees C, and 800 degrees C in sequence. The samples' permeability and acoustic wave velocity were measured after each heat treatment, and Young's modulus and shear modulus were calculated to determine the change in the mechanical properties. In addition, changes in the pore structure and surface properties were analyzed with low-pressure N-2 adsorption and SEM. The results indicate that in the range of 50-200 degrees C, the bulk water and interlayer water were removed, which alleviated the aqueous phase trapping effect, enhanced gas flow channels and increased permeability by 4-14 times. Between 400 and 600 degrees C, the coal samples started to pyrolysis, weakening the mechanical properties of the coal, and fractures were initiated and extended, which caused permeability to increase by 79-1400 times. After 800 degrees C, the surface of the coal was completely pyrolyzed, samples were cracked, and the permeability increased by more than 20,000 times. Stimulation mechanisms of FHT in CBM reservoirs consist of aqueous phase trapping alleviation, coal fractures caused by mechanical properties weakening and combustion, and finally, the C-C bond and C-O bond of molecules are broken, which induced coal fracture to produce more gas flow channels. For field application of FHT, both advantages and disadvantages are analyzed.