摘要
松辽盆地烃类气和CO2大量共存,已发现多个高含CO2气藏;CO2具有无机、有机和混合3种成因,但以无机成因为主。从已发现含CO2天然气和区域地质综合分析出发,探讨了松辽盆地潜在的CO2气源及其脱气模式。研究表明,松辽盆地主要有幔源岩浆、火山岩、碳酸盐岩和有机质4种潜在的气源,结晶基底的幔源岩浆是松辽盆地最重要的气源,特别是新生代碱性玄武岩浆;沉积盖层的火山岩是松辽盆地另一种重要的气源,营城组和登娄库组的中酸性火成岩很有可能就是昌德东CO2气藏的主力生气层;变质基底的石炭系—二叠系碳酸盐岩是今后勘探中值得关注的气源;沉积盖层和变质基底中有机质丰富,但对高含量CO2气藏的形成贡献有限。气源不同导致有利的脱气模式亦不同:幔源CO2进入沉积盆地中具有沿岩石圈断裂直接脱气模式、热流底辟体脱气模式和壳内低速高导岩浆房—基底断裂组合脱气模式;火山岩最主要的脱气模式是火山岩吸附气后期脱气;碳酸盐岩接触变质作用和动力变质作用下脱气有利于CO2气成藏。
Normal hydrocarbon gas and CO2 coexist widely and a number of gas reservoirs with large volumes of carbon dioxide have been discovered in Songliao basin.Carbon dioxide can be sourced from inorganic,organic and mixed origins,in which the inorganic origin is dominated.Based on comprehensive analysis of carbon dioxide natural gas and regional geology,gas source of carbon dioxide and its degassing model are discussed.Study reveals that carbon dioxide in Songliao basin can be from mantle-derived magma,volcanic rocks,carbonate rocks and organic matters.Mantle-derived magma in crystalline basement,especially Cenozoic alkali basaltic magma,is the most significant gas source.Volcanic rocks in sedimentary cover are another significant gas source,and medium-acidic volcanic rocks of Yingcheng and Denglouku Formations could be principal gas source in east Changde gas pool.Carbonic-Permian carbonate rocks in metamorphic basement need more attention to study as gas source in future exploration.There are abundant organic matters in sedimentary cover and metamorphic basement,but its contribution to form large volumes of carbon dioxide accumulations is little.Degassing models varies with different gas sources.There are four types of degassing models for mantle-derived carbon dioxide to migrate into basins,including direct degassing through lithospheric faults from the upper mantle,degassing from mantle diapir bodies,degassing through low-velocity and high-conduction zones as intermediate repeater and basement faults,and after-releasing of absorbed gases by volcanic rocks.Degassing of carbonate rocks in contact and dynamic metamorphisms is favorable for carbon dioxide accumulations.
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2011年第1期29-37,共9页
Natural Gas Geoscience
基金
国家自然科学基金项目玄武岩的脱气演化与二氧化碳气成藏的关系(编号:40702021)
长江中下游成矿带成矿流体系统的形成与演化(编号:40830426)
构造形成时限定年方法及其应用的探索(编号:40972134)联合资助
关键词
CO2气藏
幔源岩浆
碳酸盐岩
火山岩
松辽盆地
Carbon dioxide accumulations
Mantle-derived magma
Carbonate rocks
Volcanic rocks
Songliao basin
