东海西湖凹陷中央背斜带花港组成藏条件及主控因素分析——以H3气藏为例

Analysis of reservoir-forming conditions and key controlling factors of Huagang Formation in the central anticlinal belt of Xihu Sag of East China Sea--Taking the reservoir H3 for example

近年来,西湖凹陷中央背斜带渐新统花港组油气勘探取得重要突破,发现多个大中型含油气构造,在不同的含油气构造中,气藏的气柱高度及圈闭充满度差别大,说明不同的含油气构造具有不同的成藏主控因素。基于三维地震及多口钻井资料,从烃源岩、圈闭条件、储盖组合配置关系等方面,以H3气藏为例,通过对典型气藏的解剖,对H3气藏的成藏条件进行研究,分析了不同构造气藏的成藏主控因素。结果表明,中央背斜带油气主要来自于始新统煤系烃源岩,渐新统花港组具备良好的圈闭条件及储盖组合配置关系,油气成藏主控因素为有效的输导体系,而良好的后期保存条件则是控制油气富集程度(油气充满度)的重要因素。

A great breakthrough in oil and gas exploration has been made recently from the Huagang Formation in the central anticline belt of the Xihu Sag.Several medium to large oil and gas fields have been discovered.However,the gas column height and fullness ratio of trap differs from each other which suggests that every reservoir has its own key controlling factors.Based on seismic and drilling data,this paper selects the H3 reservoir as a case to study the accumulation conditions of source rocks,traps and combination of reservoir-cap systems.Also this paper sums up the key controlling factor of each reservoir by dissecting four typical reservoirs.The results show that the oil and gas accumulated in H3 reservoir come from the source rocks in Pinghu Formation;the reservoir and caprocks matched each other excellently,and the key factors to control oil and gas accumulation are the effective migration system and fault sealing,and the reservoir preservation condition has great influence on hydrocarbon accumulation.