论文部分内容阅读
对鄂尔多斯盆地中部上古生界煤成气特征进行了动力学模拟.通过与中部苏里格庙气田区上古生界储层中现存天然气特征对比发现,二者在干燥系数上存在明显差别,分析认为主要原因在于运移作用.同时对包括扩散作用在内的各种次生作用进行了数字模拟,从而认识到穿过盖层由扩散作用影响的天然气,富含甲烷,湿气组分含量变小;甲烷的碳司位素组成变轻,乙烷等湿气组分的碳同位素基本不变;残留天然气受之影响,特征变化一般不大,可忽略.具体到本盆地,由于扩散作用的影响,上古生界煤成天然气碳同位素特征(δ~(13)C_1=-33.46‰,δ~(13)C_2=-23.1‰,C_1/C_(1-4)=85.6％)变为残余天然气特征(δ~(13)C_1=-32.78‰,δ~(13)C_2=-23.1‰,C_1/C_(1-4)=83％);水洗作用使8％的煤成气损失,但对天然气特征影响不明显;天然气从煤系源岩排出过程中,各组分的碳同位素值变化较小,但对于干燥系数的影响比较大.
The dynamic characteristics of the Upper Paleozoic coal-formed gas in the central Ordos Basin have been simulated.Comparing with the existing natural gas in the Upper Paleozoic in the Suligemiao Gas Field, Central China, the two have significant differences in the drying coefficient. According to the analysis, The main reason is the migration, and the numerical simulations of various secondary effects, including diffusion, are made to recognize that natural gas that is diffused through the caprocks is enriched in methane and has a reduced moisture content ; The carbon isotope composition of methane is lighter and the carbon isotope of moisture components such as ethane is basically the same; the residual natural gas is affected by this, and the characteristics are not generally changed and can be neglected. Specifically, due to the influence of diffusion , The carbon isotope characteristics (δ ~ (13) C_1 = -33.46 ‰, δ ~ (13) C_2 = -23.1% o, C_1 / C_ (1-4) = 85.6%) of the Upper Paleozoic coals become the features of residual natural gas (δ ~ (13) C_1 = -32.78 ‰, δ ~ (13) C_2 = -23.1 ‰, C_1 / C_ (1-4) = 83%). The effect of water washing on the loss of 8% The influence of characters is not obvious. During the discharge of natural gas from coal-derived source rocks, the variation of carbon isotope value of each component is small, but for the drying coefficient Sound is relatively large.