滇东寒武系下统笻竹寺组页岩含气性分析

GAS- BEARING PROPERTY OF SHALE IN LOWER CAMBRIAN QIONGZHUSI FORMATION, EASTERN YUNNAN PROVINCE

寒武系下统笻竹寺组泥页岩在滇东地区分布广泛,厚度大,为南方海相沉积,有机质丰度较高,主体已经进入了高—过成熟热演化阶段,有机质类型为Ⅰ型干酪根,生气量大,脆性矿物含量高,物性条件较好,在调查井钻进过程中,出现了明显的气测异常显示,具有良好的页岩气地质基础。含气量是直接评价页岩含气性的重要参数,通过地质资料及泥页岩样品实验数据,揭示滇东地区寒武系下统笻竹寺组泥页岩含气情况及其影响因素,结果表明,含气量与有机质丰度、孔隙度、埋深存在正相关关系,与有机质成熟度相关性不明显,并且泥页岩层系中的砂岩、碳酸盐岩夹层仍具一定含气性,同时认为滇东地区寒武系下统笻竹寺组具有的页岩气勘探潜力。

The shale of Lower Cambrian Qiongzhusi Formation in eastern Yunnan Province,a marine sedimentary stratum in South China, is characterized by wide distribution, large thickness, high organic-matter abundance, and most in high- to overmature evolution degree. Furthermore, its organic matter mainly contains type-I kerogen with a strong gas-generating capability.Its physical property is good due to high content of brittle mineral. It is found that there is a clear gas logging abnormality during a drilling. Gas content is an important parameter to evaluate gasbearing property. In this study, based on some data from geology and experiments on shale of Qiongzhusi Formation, the gas-bearing property and its controlling factors were analyzed. Resultsshow that(1)there is a positive correlation existing among gas content with organic-matter abundance, porosity, and burial depth whereas no obviously correlation with organic-matter maturity;(2)gas can be also found from both sandstones and carbonates in this formation; and(3)this Qiongzhusi Formation has an exploration potential of shale gas.