摘要
致密砂岩气藏是我国近年来重要的天然气增长气藏类型,新探明的延长、川西、塔北及吐哈油田天然气均属于这种类型。通过对延长致密砂岩气藏的研究,发现这种致密砂岩气藏发育在煤系中,是一种典型的岩性气藏,这种岩性气藏存在自生自储成藏模式。延长晚古生界致密砂岩气藏发育在煤系中,部分致密砂岩含有大量煤屑或炭质泥岩颗粒。从岩心上来看,含炭屑的岩心多者可占表面积的10%~15%,少者也在2%~3%,一般均在7%~8%。这些煤屑或炭质泥岩颗粒来自于沼泽中的泥炭,是潮汐对泥炭沼泽的冲洗和河流在洪水期决口后进入泥炭沼泽对沼泽中沉积的泥炭进行侵蚀和搅浑的结果。在成岩作用中,泥炭颗粒发生煤化作用,释放出大量以甲烷为主的天然气。延长晚古生界致密砂岩气藏的R o值大部分超过了2.0,已进入有机质变质阶段。又由于砂岩本身致密,煤化过程中释放的大量天然气就会保存在砂岩中,形成这种特殊的自生自储型致密砂岩气。只要煤系中含有一定量有机质碎屑的致密砂岩就可以形成致密砂岩气,因此我国煤系致密砂岩气的储量十分巨大。
The compact sand gas is an important type that is rapidly increased in China.The Yanchang,western Sichuan,northern Tarimu and Tuha natural gas fields are all belongs to this type.By study of Yanchang compact gas field,we find that it is formed in coal-series strata,and it is of authigenic and adjacent natural gas type.Yanchang compact gas reservoir is developed in coal-series strata and the sandstone bearing gas has a great deal of coal fragments or carbonic mudstone fragments.On the core surface,there is about 10%-15%of coal fragments or carbonaceous mudstone fragments at most and 2%-3%at least,on average,7%-8%.Those coal fragment and carbonaceous mudstone fragments come from peat swamp because of being carried by rising and falling of tide and or flood of river.During diagenesis,those could be easily deformation like bitumen and filled the pore of the sandstone and make the sandstone being compacted(partially coming from clay and considerably being compacted),At the same time,the coal fragments undergo coalification under the action of temperature and pressure and release much of natural gas mainly of methane.Most of the R o value of vitrinite is beyond 2.0,which means that the coal has been metomorphised.Otherwise,owing to having much organic matter and the reservoir being very compact,the abundant natural gas will directly save in the sandstone to forming the authigenic and adjacent type of natural gas reservoir.As long as there is a great deal of sandstone that contains some amount organic matter,we can find a compact sandstone gas reservoir.So the compact sandstone gas resource in coal series should be considerably abundant in China.
作者
钟建华
倪良田
郝兵
孙宁亮
王桂林
刘圣鑫
邵珠福
王书宝
刘选
陈彬
乔向阳
ZHONG Jianhua;NI Liangtian;HAO Bing;SUN Ningliang;WANG Guilin;LIU Shengxin;SHAO Zhufu;WANG Shubao;LIU Xuan;CHEN Bin;QIAO Xiangyang(School of Geosciences,China University of Petroleum,Qingdao,Shangdong 266580,China;Dongying Institute of Geotechnical Investigation and Surveying,Dongying,Shandong 257091,China;Institue of Geomechanics,Chinese Academy of Geological Sciences,Beijing,100081,China;School of Earth Sciences,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi’an 710065,China;College of Earth Sciences,Chengdu University of Technology,Chengdu,610059,China)
出处
《中国科技论文》
CAS
北大核心
2019年第9期1029-1037,1044,共10页
China Sciencepaper
基金
国家自然科学基金资助项目(21574088)
关键词
天然气
煤屑
自生自储
致密砂岩
煤系
natural gas
coal fragments
authigenic natural gas type
compact sandstone
coal series
