川东石炭系复合圈闭储层发育主控因素研究

MAIN CONTROL FACTORS OF CARBONIFEROUS COMPOSITE TRAP DEVELOPMENT IN EASTERN SICHUAN

川东地区石炭系发育的复合圈闭主要为地层-构造复合圈闭,圈闭类型多样,充满度较好,是该区进一步勘探的主要对象之一。气藏储层具有孔隙型和裂缝-孔隙型两种类型并以后者为主,总体上具有孔径小,孔喉体系分选差,微裂缝发育,连通性较好,多具有中孔细喉特征。石炭系储层主要发育在黄二、三段中。在强剥蚀区及靠近石炭系剥蚀边界的区域是天然气储层缺失带,在其附近,可能形成复合圈闭气藏。沉积相对储集岩具有控制作用,成岩作用是决定储层储渗能力的主要条件,古隆起基础上发育的古岩溶和构造作用进一步控制和改善了储层的渗滤能力。

The composite traps developed in eastern Sichuan Carboniferous are mainly stratum-structure ones with variety of traps and fully filled,they are the one of many further explorative targets.There are pore-typed and fracture-typed gas reservoirs and the latter is dominant,in general,the pore diameter is small and the pore-throat system is poor in sorting,micro-fractures are well developed,connection is good,most of the system are characterized by mid-pore and small throat.Carboniferous reservoirs are mainly developed in Member II and III of Huang Formation.The regions in strong erosion and adjacent Carboniferous erosive margin are the lacking ones of natural gas reservoirs,nearby,there is the possibility of forming composite gas traps.Sedimentary facies controls in reservoir rocks,diagenesis determines accumulation and permeability of the reservoirs,the ancient karsting and tectonic activity developed on ancient uplift further controlled and improved permeability of the reservoirs.