川西苏码头构造侏罗系次生气藏成藏条件研究

四川盆地川西地区苏码头构造上侏罗统蓬莱镇组气藏为一典型的负压—常压浅层远源"次生气藏",在分析其气藏特征的基础上,研究了蓬莱镇组气藏的成藏条件。有效烃源岩(厚度大、有机质丰度高、生烃期长、生气强度高)为蓬莱镇组浅层气藏的形成提供了充足的气源;古构造有利于天然气的早期聚集并继承性发展,并叠加现今优越的圈闭条件;相控下发育的优质砂体为天然气富集提供了重要的储集场所;保存条件差异大,层位越深封闭性越好。总结了该区天然气的富集规律:早期聚集,中期局部破坏,晚期调整成藏定型。苏码头蓬莱镇组富集高产气受构造和储集砂体(岩性)双重控制,但更主要受控于沉积砂体的展布与储集物性的优劣。

The research on accumulation condition for secondary gas pool in Penglaizhen Formation, the Sumatou structure of West Sichuan

The shallow gas pool of Penglaizhen Formation,Upper Jurassic located in the Sumatou structure of West Sichuan is a typical subnormal-normal secondary gas pool far from source rock.Based on analysis of its characteristic,the pool-forming conditions can be study.The effective source rock which is thick,of abundant organic matter,of long period and high intension to generate hydrocarbon can supply with a plenty of gas for the shallow gas pool in Penglaizhen Formation.The paleostructure is useful for gas accumulation in the early time and succeed to develop,superposed with now-day good trapping condition.The high quality sand body controlled by sedimentary facies serve as a storage for nature gas accumulation.The preservation conditions show big discrepancy,which is the deeper,the batter.The rules for gas pool accumulation are the early accumulation,middle local destruction,and late adjustment and finalization.The enrichment and high producing of gas are controlled both by structure and sand body,especially the distribution and quality of reservoir are most important.