磨溪地区台缘带灯四段储层地质特征及其控藏作用

磨溪地区震旦系地层埋藏深,油气资源丰富,是川中地区油气增产的关键,为进一步深化对灯四段储层的地质认识,本文以岩心及薄片观察资料为基础,结合测井及生产资料,分析磨溪地区灯四段储层地质发育特征及其对气藏分布的控制作用,结果表明:磨溪地区灯四段储集岩主要为凝块云岩、藻叠层云岩、藻纹层云岩和砂屑云岩,储集空间以粒间溶孔、粒内溶孔和晶间溶孔为主,少量裂缝,储层类型为裂缝-溶洞型,裂缝及溶孔对储层渗透率起决定性作用。灯四段储层的形成受沉积作用、成岩作用和构造作用三者控制,沉积作用是储层形成的基础,构造作用和成岩作用是储层形成的关键,控制这储层的分布和储层物性的好坏。岩溶作用及储层物性与岩性分布对气藏的形成分布具有控制作用,丘滩相发育的凝块云岩和藻叠层云岩以及被岩溶作用强改造的高孔渗透段是气藏分布的有利区域。

Reservoir Characteristics and Control Effects of the Fourth Member of the Dengying Formation in the Moxi Area,Central Sichuan

The deeply buried Sinian System rich in oil and gas in the Moxi area is the key to increasing oil and gas production in central Sichuan. The study based on the observation of core and thin section, in combination with logging and production data, indicates that reservoir rocks of the Fourth Member of the Dengying Formation in the Moxi area are composed of clotted dolomite, algal stromatolite, algal lamellar dolomite and dolarenite, and reservoir space is mainly composed of intergranular dissolved pores, intragranular dissolved pores and intercrystalline dissolved pores as well as a small amount of fracture, and reservoir type is fracture-karst cave type, and the fracture and solution pore play a decisive role in the reservoir permeability. The formation of the reservoir rocks of the Fourth Member of the Dengying Formation was controlled by sedimentation, diagenesis and tectonism, while karstification, reservoir physical property and lithologic distribution got the formation and distribution of gas reservoirs under control. The clotted dolomite, algal stromatolite developed in the hilly facies and high-porosity infiltrations strongly modified by karstification are favorable gas reservoirs.