阳信-花沟地区二氧化碳气藏成藏模式

讨论了阳信花沟地区二氧化碳气的成因、运移、聚集及成藏模式.对研究区地球化学、深部地质背景、深断裂发育及火山岩分布等资料分析表明,二氧化碳主要来自无机幔源岩浆成因气体,地壳内低速异常体可能是气体初始积聚区,与之沟通的断裂输导网络是垂向运移的通道;沉积盆地内气体的释放和聚集具有明显的分带性,区内2个剪切构造带以及2个早第三纪裂谷—火山岩构造带是二氧化碳气体释放、聚集及成藏的最有利地带,二氧化碳气藏、新生代火山岩以及源幔氦同位素异常主要沿剪切构造带和裂谷火山构造带的主干断裂呈“串珠状”分布;不同构造带发育不同的二氧化碳气聚集模式和气藏类型,其中剪切构造带主要发育深层古潜山中深层背斜或断块浅层披覆构造型气藏组合;裂谷火山岩构造带主要发育火成岩伴生的二氧化碳气藏.

Formation mode of carbon dioxide gas reservoirs in Yangxin-Huagou area

The genesis,migration,accumulation and pool-forming models of carbon dioxide gas reservoirs in Yangxin-Huagou area were discussed.The data of geochemistry，deep geological background，deep faults and volcanic rock were analyzed.The results show that carbon dioxide mostly originated from inorganic mantle source and magmatic rock，which were primarily accumulated into low-velocity zones within lithosphere with a net of faults as vertical migration pathway.Two shear zones in the extensional basin and two volcanotectonic rift zones of the Paleogene with different pool-forming models and gas reservoirs are the most favorable factors for release and accumulation of carbon dioxide as well as formation of gas reservoirs.The distribution of the gas reservoirs,volcanic rock of the Cenozoic and helium isotope anomaly from inorganic mantle source showed the string-beads form along the principal faults of shear zones and volcano-tectonic rift zones.A gas reservoir assembly of the deep buried hills and medium-deep anticlines or fault-blocks and shallow draping deformational traps developed in the shear zones,and the gas reservoirs associated with igneous mass existed in the volcano-ectonic rift zones.