混源气藏及混源比例研究

STUDY ON SOURCE-MIXED GAS RESERVOIRS AND SOURCE-MIXED RATIOS

天然气具有多源、多阶生成和流动性强的特点 ,在盆地中混源成藏具有普遍性。国内外研究表明 ,同源两阶和两源不同阶的混源气最为常见 ,同一类型母质在不同演化阶段生成的甲烷、乙烷稳定碳同位素与其母质成熟度具有定量关系。考虑不同源天然气的混合成藏主要为物理作用 ,则可以利用模拟实验和实测混源气的稳定碳同位素组成等数据 ,确定同源不同阶或两源不同阶天然气的混源比例。对塔里木盆地库车坳陷克拉 2混源气藏进行的研究效果良好。

Natural gas is of the characters such as multisource and multistage generation and strong flowability, and it is common to form source-mixed gas reservoirs in a basin. Through investigating at home and abroad, it was indicated that the source-mixed gases are mainly composed of the ones generated from the same source rocks with tow mature stages or from the tow different source rocks with various mature stages; and the stable carbon isotopes of the methane and ethane generated from the same type of kerogens in different evolution stage are of a quantitative relation to the maturities of their kerogens. In consideration of that the source-mixed gas reservoir formation is mainly a physical function, the ratio of the source-mixed gases generated from the same source rocks with various mature stages or from the tow different source rocks with various mature stage may be determined by use of the simulation test results and the data on the measured stable carbon isotopic compositions of the source-mixed gases. The result of studying the Kela-2 source-mixed gas reservoir in Kuche Depression of Talimu Basin by use of such a method were very good.