西湖凹陷深部储层物性特征及其影响因素

依据已钻井的物性测试、铸体薄片等基础资料,通过分析西湖凹陷深部储层内的沉积、岩石学特征、物性、孔隙类型及分布特征,表明该区砂岩储层的岩石成分相对较杂、成熟度中等,但长石、岩屑等可溶性成分含量高,易被溶蚀形成大量次生孔隙,对储层物性有积极改善作用。保俶斜坡带平湖组砂岩属潮汐三角洲前缘分流河道、潮汐砂坝,“泥包砂”垂向交互方式的地层构型特点有利于形成多期次次生孔隙带;中央背斜带花港组砂体属辫状河道、辫状分流河道微相,砂体分布广,具备下粗上细的地层结构,属“旋回式”侧向交互方式的地层构型,在与深洼泥岩连通的方向上有利于厚层砂体的溶蚀改造,具备形成大型油气藏的有利条件。

Physical Characteristics and Influencing Factors of Deep Reservoirs in Xihu Sag

Based on the basic data of physical properties and thin sections, the sedimentary, petrological characteristics, physical properties, pore types and distribution characteristics of the deep reservoirs in Xihu Sag are analyzed. It shows that the deeps and stone reservoirs have multiplicity rock composition and medium component maturity. The content of soluble components such as feldspar and cuttingsis favorable are high. It is easy to be dissolved to form a large number of secondary pores, and has positive effect on the physical properties.The environment of Pinghu Formation in Baochu Slope includes the distributary channel and sand dam of delta.The typical of "mud-encased sand" mode is beneficial to form the secondary pore growth zones with multiple stages. Huagang Formation has a different environment with braided channel and braided distributary channel in the central anticline belt. The sand bodies are extensively distributed. The typical of "cycle" mode is beneficial to the dissolution of thick sand bodies in the direction where the sandstone in the central anticline beltis connected with the mudstone in Santan Depression. And it has favorable conditions for the formation of large oil and gas reservoirs.