摘要
裂谷盆地岩浆活动强烈,其中侵入岩区的天然气资源丰富且天然气性质异常。为深入研究侵入岩区的天然气成因,对沾化凹陷孤北地区天然气和气源岩的地球化学特征进行了系统分析。结果发现,孤北地区侵入岩区的气源岩过成熟,天然气中无机成因二氧化碳和硫化氢含量较高、烷烃碳同位素较重、天然气性质变化较大。结合天然气成因和同位素分馏理论分析,认为造成天然气性质异常的原因是侵入岩区气源岩除经历正常的热演化作用外,还受到岩浆及岩浆流体的高温烘烤作用,导致有机质发生多阶演化、多次生烃以及碳酸盐岩(或硫酸盐)分解;岩浆流体混入也使天然气组成进一步复杂化。侵入岩区天然气不仅具有普遍混合性,而且具有多重(多源、多阶、多期及烃类气体与非烃类气体)混合性;由于混合类型及混合比的不同,导致天然气性质存在明显差异。
There were violent magma activities which have caused rich and abnormal petroleum with chemical properties in igneous rocks region of rift basins.In order to further study the natural gas origin,we did systematic analysis on geochemical characteristics of gas and source rocks in Gubei area.It is shown that,some source rocks are over-matured,and there were more inorganic CO2 and H2 S in the gas with heavy alkane carbon isotopes and significant variable properties.Based on the theory of natural gas origin and isotope fractionation,we thought that the source rocks are subjected not only to normal thermal evolution by burial,but also to frequent heating by magma,which have led to the multistage evolution of organic matter,hydrocarbon generation,and decomposition of carbonate rock. In addition,the interfusion of magma liquid also made the gas compositions more complex.Finally,we indicated that the gas possessed the characteristics of universal mixture and multifold mixtures(that is multi-source gas,multi-stage evolution,multi-times hydrocarbon generation,hydrocarbon and non-hydrocarbon mixture),and the difference of mixing types or mixing proportion led to the variability of the gas chemical compositions of intrusive rocks region.
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2013年第4期1-4,16,共5页
Petroleum Geology and Recovery Efficiency
