四川盆地安岳气田震旦系气藏叠合岩溶发育模式与主控因素

通过对四川盆地安岳气田震旦系气藏岩溶储层发育特征和完钻气井测试产能综合分析，从碳酸盐岩岩溶储层发育机制出发，提出叠合岩溶概念和发育模式，明确了叠合岩溶发育主控因素及其对完钻气井产能的控制作用。利用岩心、成像资料，考虑储集空间类型、大小以及缝洞搭配关系，将灯影组四段（灯四段）岩溶储层划分为缝洞型、孔洞型和孔隙型3种类型，缝洞型和孔洞型是灯四段优质储层。受原始沉积体岩性、物性及岩溶期古地貌特征差异影响，岩溶风化溶蚀深度、优质储层垂向发育位置及平面展布范围等特征存在差异。建立了“差异溶蚀”的叠合岩溶发育模式，指出丘滩体沉积特征、两期风化壳叠合程度、岩溶期断裂系统发育规模以及构造翻转的地质过程综合控制了叠合岩溶储层发育，同时叠合岩溶发育强度控制气井产能分布。叠合岩溶发育区是气藏开发优先目标，其储层发育模式与主控因素的研究对于安岳气田震旦系气藏开发评价、建产区筛选和井位部署具有重要的指导意义。

Development patterns and constraints of superimposed karst reservoirs in Sinian Dengying Formation,Anyue gas field,Sichuan Basin

Comprehensive analyses of karst reservoir development characteristics and productivity testing of completed wells in the reservoirs of the Sinian Dengying Formation, Anyue gas field, Sichuan Basin, are combined with the development mechanisms for carbonate karst reservoirs to propose a concept and development model of superimposed karst and clarify their main controlling factors and effect on gas well performance. According to core, imaging data, reservoir space type, size and the configuration between fractures and cavities, the karst reservoirs are classified into three types: fracture-cavity type, pore-cavity type and pore type. High-quality reservoirs in the fourth member of the Dengying Formation in the field mostly belong to the first two types. Influenced by the differences in the initial lithology and physical properties of sedimentary strata and in paleogeomorphology characteristics during karst period, the karst reservoirs vary in terms of dissolution depth, vertical development locations and plane distribution range. A development model with differential dissolution for superimposed karst is thus proposed. It is also suggested that the sedimentary characteristics of microbial mounds and shoals, the overlapping two-stage weathering crust, the development scale of fault-fracture systems and the geological process of tectonic inversion control the development of superimposed karst reservoirs. Apart from that, superimposed karst development intensity also controls gas well performance. Based on these understandings, it is suggested a development priority on superimposed karst reservoirs in the basin. The study of development model and the controlling factors of these reservoirs is helpful in gas reservoir development evaluation, production area screening and well emplacement in the area.