井下注气强化煤层气抽采效果的工程试验与数值模拟  

Test and numerical simulation on effect of enhanced coalbed methane drawing by injecting gas under coal mine

作　　者：李志强[1,2] 王兆丰[1] 

机构地区：[1]河南理工大学河南省煤矿瓦斯与火灾防治重点实验室,河南焦作454000 [2]重庆大学西南资源开发及环境灾害控制工程教育部重点实验室,重庆400044

出　　处：《重庆大学学报（自然科学版）》2011年第4期72-77,82,共7页Journal of Chongqing University

基　　金：国家重点基础研究发展计划(973计划)资助项目(2009CB724606);国家自然科学基金青年基金资助项目(51004041);国家创新研究群体基金资助项目(50621403);教育部科学技术研究重点项目(109130)

摘　　要：为提高特低渗透煤层的煤层气抽采效果,在重庆天府矿业公司850m深井,采用注入组分为78%的N2的方法,进行了强化注抽煤层气的工业性试验。分别试验了单孔与多孔干扰情况下自然涌出、负压抽采、注气涌出、边注边抽和间歇注气试验。结果表明:在常规抽采达到极限后进行注气,甲烷抽采时间-浓度曲线呈现先上升后下降的单峰波形状态,间歇注抽的甲烷浓度高于边注边抽的甲烷浓度,但衰减较快,注气距离短,长时边注边抽的注抽效果好于间歇注抽效果。注气孔网间距4m,渗透率1.112×10-4 mD的煤层,连续注抽5d后,抽采率由卸压后负压极限抽采的52.4%提高到58.6%。建立了空气注采甲烷的渗流理论方程,计算了合理的注气孔网间距、注气时间、压力等技术参数,讨论了注气技术方法的适用条件和辅助技术,为推广这一技术提供了工程与理论参考。同时,提出了抽采后注气的变定解条件渗流方程解算的科学问题。In order to improve the extraction effect of ultra-low permeability coalbed methane,injecting and drawing industry test of enhanced coalbed methane recovery is carried out by injecting concentration 78% N2 under 850 m depth coal mine of Tianfu Mining Co.Ltd.,in Chongqing.The experiments of free methane emission,vacuum pumping,side injecting and side emission,side injecting and side drawing and intermittent injecting are tested under the condition of single hole and multi holes respectively.The testing results indicate that time-concentration curve of methane drawing is a single peak wave curve which increases and decreases during injecting N2 after reaching the limits of ordinary extraction.The methane concentration of intermittent injecting gas is greater than that of side injecting and side drawing.However,the former declines rapidly and has a shorter migration distance than the latter.The injecting effect of long time side injecting and side drawing is better than that of intermittent injecting.When hole space is 4 m,permeability 1.112×10-4mD,the methane recovery ratio increases to 58.6% from conventional recovery ratio 52.4% after injecting 5 day.Meanwhile,the seepage flow equation of injecting air is provided and the parameters,such as rational hole mesh space,time and pressure of injecting gas,are simulated.At the same time,application condition and assistant technology about injecting gas are discussed,which provides engineering and theoretical reference to promote the injecting gas technology.Also,the problem of variable definite conditions seepage flow equation is put forward.

关 键 词：煤层气 瓦斯 注气 渗流 变定解条件 

分 类 号：TD713[矿业工程—矿井通风与安全] P618[天文地球—矿床学]