Tian Wei, Yang Wei, Luo Liming, Si Guangyao, Zhang Zhaoyang, Zhang Zhichao
Key Laboratory of Coal Methane and Fire Control, Ministry of Education, China University of Mining and Technology, Xuzhou 221116, China.
School of Minerals and Energy Resources Engineering, University of New South Wales, Kensington, Sydney ,NSW 2205 , Australia.
ACS Omega. 2024 Jun 18;9(26):28754-28763. doi: 10.1021/acsomega.4c03121. eCollection 2024 Jul 2.
Gassy coal seams generally have low permeability and dry coal bodies, which are susceptible to coal and gas outburst hazards in the process of mining. Water injection into coal seams can significantly alter the gas release rate and flow behavior. However, water has dual effects on coal seams: gas displacement and water-locking, and the coupling mechanism of these two effects is not clear in the whole process of coal seam water injection. By measuring high-pressure gas adsorption isotherms and gas diffusion initial velocity, it was found that both the Langmuir adsorption constant and gas diffusion initial velocity Δ decrease with the increase of water content, which would reduce outburst risks. Through the self-developed integrated experimental device of "gas adsorption + water injection displacement + gas desorption″, the changing rules of gas displacement amount, desorption amount, and water lock amount under different water injection conditions were studied. The results show that when the water injection ratio increases from 6 to 25%, the gas displacement would increase from 0.62 to 1.16 mL/g, with an increase of 87.09%. Also, at the same time, the gas desorption capacity would decrease from 4.86 to 4.05 mL/g after pressure relief, with a decrease of 16.67%. The amount of water-locking increased from 0.11 to 0.38 mL/g. The effect of water injection to control coal and gas outburst occurs in two different water injection stages. In the process of water injection, water plays a major role in gas displacement, which is conducive to reducing the gas content of the coal seam. After the completion of water injection, the static water pressure remaining in the coal seam can reduce the gas emission rate. The combination of these two effects can effectively reduce the risk of outbursts.
瓦斯含量高的煤层通常渗透率低且煤体干燥，在开采过程中易发生煤与瓦斯突出灾害。向煤层注水可显著改变瓦斯释放速率和流动特性。然而，水对煤层有双重作用：瓦斯置换和水锁作用，且在煤层注水全过程中这两种作用的耦合机制尚不清楚。通过测定高压瓦斯吸附等温线和瓦斯扩散初速度，发现兰氏吸附常数和瓦斯扩散初速度均随含水量增加而降低，这将降低突出风险。通过自主研发的“瓦斯吸附+注水置换+瓦斯解吸”一体化实验装置，研究了不同注水条件下瓦斯置换量、解吸量和水锁量的变化规律。结果表明，当注水率从6%增加到25%时，瓦斯置换量从0.62 mL/g增加到1.16 mL/g，增幅为87.09%。同时，卸压后瓦斯解吸量从4.86 mL/g降至4.05 mL/g，降幅为16.67%。水锁量从0.11 mL/g增加到0.38 mL/g。注水防治煤与瓦斯突出的效果体现在两个不同的注水阶段。注水过程中，水主要起瓦斯置换作用，有利于降低煤层瓦斯含量。注水结束后，煤层中剩余的静水压力可降低瓦斯排放速率。这两种作用相结合可有效降低突出风险。
