四川盆地泸州西部须家河组天然气成藏期次

The timing of gas accumulation in the Xujiahe Formation of western Luzhou,Sichuan Basin

为进一步明确四川盆地泸州西部地区上三叠统须家河组勘探目标,对该区须家河组天然气成藏期次进行了研究,以确认天然气成藏过程和成藏主控因素。通过对储层显微荧光薄片观察和流体包裹体特征与均一温度分析,同时结合地温史和生烃史,综合确定并认为泸州西部地区须家河组天然气具有3期成藏的特点:①初次成藏期发生在中晚侏罗世,主要形成低演化的煤系气;②主要成藏期发生在燕山运动晚幕的白垩纪晚期和末期,是须家河组煤系烃源岩大量生排烃期,也是最高演化程度的时期;③第三阶段为深层来源气的主要成藏期和各类天然气调整期,主要发生在喜山运动阶段。

In order to further clarify the exploration targets in the Xujiahe Formation of western Luzhou in the Sichuan Basin,we studied the timing of gas accumulation in the Xujiahe Formation and identified the process and main controlling factors of gas pooling.Based on the microscopic observation of thin section,and the analysis of fluid inclusion and homogenization temperature,in combination with geothermal history and hydrocarbon generation history,it is believed that the gas in the Xujiahe Formation accumulated in three stages.The first stage occurred in the Middle-Late Jurassic and was dominated by the coal measure gas with low thermal maturity.The second stage occurred in the late Cretaceous during the late Yanshan movement,when the coal measure gas was in peak generation and expulsion and also the highest thermal maturity.The third stage occurred in the Himalayan epoch when the deep-sourced gas accumulated and various gas reservoirs adjusted.