崖南凹陷烃源岩生烃及碳同位素动力学应用

HYDROCARBON-GENERATING DYNAMICS AND CARBON ISOTOPE DYNAMICS OF THE SOU RCE ROCKS IN YANAN SEG

针对目前琼东南盆地崖南凹陷天然气系统勘探存在的地球化学问题,采用近几年发展起来的生烃动力学及碳同位素动力学研究方法,以崖城组烃源岩干酪根热解生烃实验获得的气体产率和碳同位素数据为基础,建立了生烃动力学和碳同位素动力学模型,初步圈定崖13-1气田天然气主要来自崖南凹陷斜坡带崖城组含煤地层,烃源岩埋深在4300～6000 m之间,目前正处在主生气阶段;崖城组热解气碳同位素动力学研究表明,崖13-1气田天然气成藏时间较晚,属于'累积'集气成藏,成熟度在1.5%～2.3%之间,显然为烃源岩气窗阶段充注,因此有利于气藏形成与保存.

The research methods of hydrocarbon-generating dynamics and carbon isotope dynamics, which have been developed in recent years, were adopted in consideration of the geochemical problems existing currently in gas exploration in Yanan Seg in Qiongdongnan Basin. Through setting up the hydrocarbon- generating dynamic model and carbon isotope dynamic model on the basis of the gas yield and carbon isotope data collected from the hydrocarbon-generating experiments of pyrolyzing kerogens in the source rocks of Yacheng Formation, it was primarily concluded that the natural gas in Ya 13-1 gas field mainly came from the coal-bearing layers of Yacheng Formation at the slope zones of Yanan Seg; The burial depths of source rocks range from 4300 m to 6000 mi and, the source rocks are in the peak gas-generating stage now. According to the research on the carbon isotope dynamics of pyrolysis gas of Yacheng Formation, it was indicted that the reservoir formation of Ya 13-1 gas field was late; and it belonged in an 'integral' gas accumulation and was charged at the gas window stage of source rocks with Re of 1.5%-2.3%, thus being beneficial to the gas reservoir formation and preservation.