东海盆地西湖凹陷热事件对储层的改造及其机理探讨

东海盆地西湖凹陷近年来的勘探研究表明,与热事件相关的溶蚀作用是深部储层(≥3 300 m)次生孔隙发育的重要因素之一。通过利用磁场、热场及三维地震对研究区火山发育特征的研究,结合薄片观察、场发射能谱环境扫描电镜等实验方法及物性分析等资料,对西湖凹陷深部储层与热事件相关的溶蚀作用进行研究。结果表明,砂岩储层受热事件的改造作用主要表现在热流体携带酸性物质及加速烃源岩热演化释放有机酸等因素导致储层次生孔隙发育。研究了热事件对不同储层发育部位的改造作用,探讨了热液事件改造储层的机理,进而指出了热液改造影响储层的区域分布规律。

Reservoir formation and modification controlled by thermal events in the Xihu Sag,East China Sea Basin

There have been many hydrocarbon explorations in the Xihu Sag of the East China Sea Basin recently, and these have shown that reservoir dissolution controlled by thermal events have impacted hydrocarbon accumulations in those formations over 3 000 m deep.We aimed to clarify these thermal events, and their control on reservoir dissolution, by using magnetic field, thermal field and 3D seismic datasets, and in particular to investigate the characteristics of ancient volcanos in the study area.Our study used core samples, thin sections, field emission spectroscopy environmental scanning electron microscopy (SEM) and physical properties.Thermal fluids carrying acids accelerated source rock evolution which released further organic acids.These acids led to the generation of secondary pores which modified the original sandstone reservoirs.In view of reservoir developments in different areas, we discuss the mechanism of reservoir reconstruction by thermal events, and predict the likely distribution of reservoirs influenced by thermal events.