摘要
在页岩气勘探中,首先寻找高有机质丰度的页岩已被广泛认可.研究页岩中有机质的富集机理,认清沉积环境与页岩中有机质丰度的关系对页岩气勘探非常重要.黔西北地区下寒武统牛蹄塘组底部广泛发育黑色页岩.在有机化学与元素化学相结合的基础上,对其进行了精细研究.发现其有机质含量丰富,有机碳的质量分数大多超过3.0％,有机质类型以Ⅰ型为主且有机质演化成熟度Ro介于2.0％ ～3.0％,从烃源岩的角度作为页岩气源岩具有很好的勘探前景.同时,黑色页岩中Ba、As、U、P、Mo等元素大量富集,Sr、Al、Ti、Mg等元素含量较低,显示其形成于缺氧的还原环境当中,同时又伴随热液活动作用的影响,有机碳的质量分数与表征缺氧环境和热液活动的元素化学参数w（Cu） /w （Zn）、δU和w（Si） /w （Al）、w（U） /w （Th）等的质量分数具有很好的相关性,缺氧的沉积环境和热液活动是这套富有机质页岩形成的主控因素.
In shale gas exploration, the shales with high-abundance organic matter are usually widely focused, so it is very important for the exploration to figure out the enriching mechanism of the matter and make clear of the re- lationship between the depositional environments and the abundance. The black shales of Lower Cambrian Niuti- tang Formation in Northwest Guizhou are widely developed. Based on the integration of the organic chemistry and element chemistry, the detailed studies on the above are conducted. The rich and high organic matter abundance is found, TOC＇ s mass fraction is mostly more than 3.0%, the type of the matter mainly belongs to Type I and the e- volved organic matter maturity （ Ro ） is in the range of 2. 0% -3. 0%, from the viewpoint of hydrocarbon source rocks, the shales are regarded as the shale gas source rocks with much better exploratory prospects. At the same time, the element-content mass fractions of the Ba, As, U, P, Mo and so on in the black shale are very high ; the element ＇ s mass fractions of St, A1, Ti, Mg and other elements are very low, such geochemical features of the black shales are related to in the reducing environment of hypoxic environment, and in the meantime joined with the influ- ences of the hydrothermal activities. There are much better correlation in the mass fractions for the TOC and the el- ement chemical parameters such as w （Cu） /w （Zn）, δU and w （Si） /w （A1）, w （U） /w （Th） and so forth characterizing the hydrothermal activities and hypoxic environment, the hypoxic depositional environment and hydrothermal activities are the main controlling factors for this set of organic shale rocks to generate.
出处
《大庆石油地质与开发》
CAS
CSCD
北大核心
2014年第4期158-165,共8页
Petroleum Geology & Oilfield Development in Daqing
基金
贵州省国土资源厅项目(2012GYYQ-01)
关键词
缺氧环境
热液活动
黔西北
下寒武统
牛蹄塘组
页岩
有机质丰度
hypoxic/anoxic environment
hydrothermal activities
Northwest Guizhou
Lower Cambrian Series
Niutitang Formation
shale
organic matter abundance
