川东北五宝场构造沙溪庙组储层特征

五宝场构造中侏罗统沙溪庙组气藏是目前川东北地区在沙溪庙组地层中首先发现的气藏，也是川渝地区低效油气合作开发的重点目标。为此，通过沉积相、物性、横向分布等多方面分析研究，确定沙溪庙组储层具有以下特征：以中砂质粗粒、粗砂质中粒岩屑长石砂岩为主，岩性质纯、性脆；具有低胶结物含量、低成分成熟度、高结构成熟度岩石学特征；储集空间可分为洞穴、孔隙、裂缝和喉道3大类12个亚类，以次生溶孔为主要储集空间；裂缝是油气渗滤的主要通道，储集类型以裂缝-孔隙型为主；孔隙结构特征表现为：分选中等偏低、中低孔隙度中小喉型；加砂压裂对沟通储层、改造储层效果较好；沙二段底部嘉祥寨砂岩储层物性好、横向可追踪，是勘探首选产气层。

RESERVOIR CHARACTERISTICS OF SHAXIMIAO FORMATION IN WUBAOCHANG STRUCTURE, NORTHEASTERN SICHUAN BASIN

The Shaximiao Formation gas pool in Wubaochang structure is the first gas pool discovered in the Middle Jurassic Shaximiao Formation in the northeastern Sichuan Basin so far. There are 4 wells completed in this gas pool now, of which 2 wells have been tested to get commercial gas flow. Based on comprehensive analyses of sedimentary facies, physical properties and lateral distribution, the features of the Shaximiao Formation reservoirs are recognized. The reservoirs are mainly composed of pure and brittle moderate sandy lithic arkose and arenose lithic arkose. Their petrological features include low content of cements, low compositional maturity and high textural maturity. The reservoir spaces can be divided into 3 categories (cavity, pore, fracture and throat) and 12 types, and are dominated by secondary dissolved pores. The reservoirs are mainly of fracture-pore type, with fractures acting as the main percolation pathways of hydrocarbons. The pore configuration is characterized by the moderate to the low side sorting, moderate-low porosity, and moderate-small throat. Sand fracturing is effective in improving reservoir quality. The Jiaxiangzhai sandbody in the 2nd member of the Shaximiao Formation has good poroperm characteristics and can be traced laterally, thus it is the most favorable target of gas exploration.