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根据天然气地质、地化特征 ,利用烃类气与非烃气碳、氮同位素及稀有气体氦同位素等多项地化指标并结合地质综合分析结果 ,划分了莺 -琼盆地烃类气与非烃气成因类型。在气源岩评价的基础上 ,采用多项地化指标综合对比 ,确认上第三系中新统 -上新统下部海相泥岩是莺歌海盆地泥底辟带浅层烃类气的主力气源岩 ,下第三系渐新统滨海沼泽相含煤岩系泥岩和半封闭浅海相泥岩是琼东南盆地崖 13- 1气田烃类气的主要气源岩。利用在本区建立的δ1 3C1 - Rc关系方程 ,判识泥底辟带浅层烃类气源岩的成熟度处于成熟 -高成熟阶段 ,而崖 13- 1气田烃类气源岩尚处在成熟阶段。 CO2 气则主要来自受泥底辟及热流体上侵活动强烈影响发生碳酸钙热分解的中新统海相含钙砂泥岩。
According to the geology and geochemical characteristics of natural gas, the use of a number of geochemical indicators, such as hydrocarbon gas and non-hydrocarbon gas, nitrogen isotope and rare gas helium isotope, combined with the results of geological comprehensive analysis, the hydrocarbon gas and non-hydrocarbon Gas genetic type. Based on the evaluation of gas source rocks and comprehensive comparisons of a number of geochemical indicators, it is confirmed that the marine mudstone in the lower Miocene-Pliocene of the Upper Tertiary is the main force of the shallow hydrocarbon gas in the mud belt of the Yinggehai Basin Gas source rocks and Lower Tertiary Oligocene coastal marsh facies coal-bearing rock mudstone and semi-closed shallow marine mudstone are the main source rocks of hydrocarbon gas in the Yaxi 13-1 gas field in the Qiongdongnan Basin. Using the δ1 3C1 - Rc relational equation established in this region, the maturity of the shallow hydrocarbon source rocks in the diapir zone is judged to be mature to high maturity. However, the hydrocarbon source rocks in the Yaxia 13-1 gas field are still in the Mature stage. The CO2 gas is mainly derived from the Miocene marine calc-sands and mudstones that are strongly affected by the uplift of mud diapirs and thermal fluids.