松辽盆地徐家围子断陷深层天然气成藏期研究

热指标反演恢复表明,松辽盆地徐家围子断陷兴城地区古热流值在距今65Ma时达到最大值96.3mW/m²,同时平均地温梯度高达5.0℃/hm。盆地模拟计算结果表明,徐家围子断陷烃源岩从距今110Ma开始快速生气,在距今95Ma和75Ma出现了两次显著的生气高峰。火山岩储层包裹体均一温度显示,徐深1井营城组天然气成藏温度为115℃~186℃。包裹体均一温度和储层热演化史综合分析表明,徐家围子断陷兴城地区深层天然气成藏期是距今103~60Ma,即成藏期出现在登娄库组盖层形成以后,这对该地区深层天然气的保存比较有利。

Research on reservoir-forming time of deep natural gas in Xujiaweizi faulted-depression in Songliao Basin

Maximum paleoheat flux is 96.3mW/m² and the average geothermal gradient is 5.0℃/hm at 65Ma bp in Xingcheng area of Xujiaweizi faulted-depression in Songliao Basin according to thermal indictors inversion. The result of basin modeling and calculating indicates` that natural gas of hydrocarbon sources was quickly generated from 110Ma bp and two obvious gas-generating peaks occurred in individually 95Ma bp and 75Ma bp in Xujiaweizi faulted-depression. Homogenization temperatures of inclusion in the volcanic reservoirs prove that eservoir-forming temperature range of natural gas in Yingcheng Formation in Xushenl Well is from 115℃ to 186℃. The synthetic analysis of the inclusion homogenization temperatures and reservoir thermal-evolution history indi-cates that reservoir-forming time of the deep natural gas in Xingcheng area of Xujiaweizi faulted-depression are about from 103Ma bP to 60Ma bp. The reservoir-forming time occurred after the deposition of Denglouku Formation which is cap rock，which is of advantage to conservation of deep natural gas in this area.