构造煤中煤层气扩散_渗流特征及其机理

第17卷第1期2010年1月

地学前缘(中国地质大学(北京);北京大学)

Earth S cien ce Frontiers (Ch ina University of Geosciences(Beijing);Peking University)Vol.17No.1Jan.2010

收稿日期:2009 03 11;修回日期:2009 06 21

基金项目:国家重点基础研究发展计划 973 项目(2009CB219601,2006C B202201);国家自然科学基金项目(40772135,40642013,40172058);国家科技重大专项课题(2008ZX05039 003)

作者简介:陈富勇(1962 ),男,硕士,高级工程师,主要从事煤田地质与勘探研究。E mail:cfy2008yx@

*

通讯作者简介:琚宜文(1963 ),男,博士,教授,主要从事构造地质和煤层气地质研究。E mail:juyw 03@

构造煤中煤层气扩散 渗流特征及其机理

陈富勇1

,!琚宜文

2,*

,!李小诗2,!范俊佳2,!梁!英

3

1 淮北矿业(集团)有限责任公司地质测量处,安徽淮北235000

2 中国科学院研究生院地球科学学院,北京100049

3 河北煤田地质局煤田物测队,河北邢台054000

Chen Fuyo ng 1,!Ju Yiw en 2,*,!Li Xiao shi 2,!Fan Junjia 2,!Liang Ying 3

1 G eolog ical S urv e y Depar tme nt of Anh ui H uaibei M ining Group C omp any ,H uaibei 235000,China

2 College of E arth Sc ienc e,Gr adu ate Univ ersity of Chinese A cad emy of Sc ienc es,Be ij ing 100049,China

3 G eoph ysic al and G eolog ical Div ision ,H ebei Bu reau of Coa l Geolog y ,X ing tai 054000,China

C hen Fuyong,Ju Yiw en,Li Xiaoshi,et al.Diffusion osmosis characteristics of coalbed methane in tectonically deformed coals and their mechanism.Earth Science Frontiers ,2010,17(1):195 201

Abstract:T her e a re t hr ee stag es fo r the pro ductio n of coalbed methane:deso rptio n,diffusio n and osmo sis.T he diffusio n pr ocess of methane and multi co mpo nent g ases in the deformed coals is not co nsistent w ith that in primar y coals.T he chang e of ex ter nal pr essure is only an exter na l fact or in the w hole pro cess of adsor ption desor ption in tectonically defor med coals;the essential factor s o f the pro cess ar e the defo rmation,the change of str ucture and the adsor pt ion potential.T hose facto rs ar e the r oo t causes w hich induce the ir rever sible process o f deso rptio n.W hen the ba lance of co al and multi g as like CH 4has been destro yed,the tectonically de formed coals that deformed stro ng er show s a phenomenon of hyster esis o f desor ption after the pr essure r e duced,and the g as in w eakly deformed co al will deso rb quickly.T he pr ocess of deso rption has two phases:one is the g as desor ption and the other is the pr ocess of free g as fro m micro po res diffusing to the bigg er pores;the latt er one deter mines the gas diffusion rate.T he g as diffusion mechanism o f tectonically defor med co als was deter mined by por e shape,size,co nnectiv ity and the pro pert ies and condition of multi g as.Ductile defor mation coal has many micr o por es and its diffusio n mo de is the K nudsen diffusion.Brittle defor mation coa l has many bigg er po res and the co nnectiv ity o f po res is much better,so the diffusio n mode is t he Fick diffusion.T he dif fusio n mo de of br ittle ductile defor mation coal is the transitional diffusion.T he well test osmosis of brittle de format ion coal is hig her t han that of ductile defor mation co al and the well test osmo sis of primar y structure coa l is the lo west.T her e are many mesopo res in brittle defor matio n co al,and t he others ar e micr opores;sub mi cr opor es and ultra micropor es cannot be detected.T he br ittle defor matio n also can increase t he connectivity of po res.Ductile defo rmation co al has a small amount o f meso po res,and the amo unts of micr opores and sub mi cr opor es increase fast;the pr ocess of diffusion and o smo sis happened in meso po res and micr opor es,so the w ell test osmosis of duct ile defor mation coal was low er than t hat o f britt le defo rmation co al.Key words:tect onically defor med coals;coalbed met hane;desor ption &diffusion;o smo sis