川北地区灯影组四段优质储层特征及控制因素

为了解决川北地区震旦系灯影组四段储层特征和控制因素认识不清的问题，基于四川盆地北缘露头剖面及岩心观测，通过薄片鉴定、扫描电镜、包裹体、阴极发光、储层物性等研究，分析了灯四段储层岩石学、储集空间、成岩作用及物性等特征，并利用地震资料恢复古地貌，探讨了优质储层发育的控制因素。结果表明：川北地区灯四段储层的岩石类型以颗粒粘连白云岩、藻叠层白云岩及粉-细晶白云岩为主，储集空间以藻黏结格架孔、晶间溶孔及近顺层溶蚀孔洞为主，储层总体具有低孔、低渗特征，但局部地区仍具有发育中孔、中高渗优质储层的条件。受裂陷槽边缘古地貌高地控制发育的台缘丘滩、台内丘滩相带是优质储层发育的物质基础，在中-深埋藏阶段与烃源岩热演化有关的埋藏溶蚀作用是控制灯四段储层大量溶蚀孔洞发育的关键，而表生岩溶作用的影响较弱。优质储层位于绵阳-长宁裂陷槽东缘的元坝西-阆中区块，为台缘丘滩与埋藏溶蚀作用叠加部位，它是川北地区灯四段油气勘探的有利区带。

Characteristics and controlling factors of high-quality reservoirs of the fourth member of Dengying Formation in northern Sichuan Basin

To clear the characteristics and main controlling factors of Dengying Formation reservoir in northern Sichuan Basin,field outcrops and drilling core observation,rock thin-film identification,scanning electron microscopy,inclusion,cathodoluminescence,reservoir physical property testing were used to analyze the characteristics of petrology,reservoir space,diagenesis and physical properties,seismic data were used to recover the ancient geomorphology,and then the main controlling factors of the reservoir were discussed. The results show that the reservoir rocks are mainly composed of particle-bonded dolomite,algal stromatolitic dolomite and silty-fine dolomite. The reservoir space is dominated by algae-bonded lattice pores,intercrystalline dissolved pores and nearlayered dissolved pores. The reservoir generally has the characteristics of low porosity and low permeability,but high-quality reservoirs with medium pore and high permeability are developed in some areas. The platform marginal mounds and platform inner mounds facies controlled by paleo-geomorphic highlands on the edge of the rift trough are the basis for the development of high-quality reservoirs. Buried dissolution associated with thermal evolution of source rocks in the middle-deep burial stage is the key to controlling the development of a large number of dissolved pores in the fourth member of Dengying Formation. Whereas,the epigenetic karst has a weaker impact on the reservoir. High-quality reservoirs are developed in the western Yuanba to Langzhong block in the eastern margin of Mianyang-Changning rift trough,which is the superimposed favorable area for the marginal mounds facies and burial dissolution. It is a favorable gas exploration zone in northern Sichuan Basin.