松辽盆地营城组火山岩储层流动单元特征和控制因素

Charactertics and controlling factors of volcanic reservoir flow units of Yingcheng Formation in the Songliao Basin

根据孔隙度、渗透率、储层品质指数(RQI)、流动层带指数(FZI)4个参数对XS1井区白垩系营城组火山岩的388个样品进行聚类分析,通过对聚类结果与各井产气情况的对比将储层流动单元划分为4类,所占比例依次为39.2%(Ⅲ类)、33.2%(Ⅱ类)、25.0%(Ⅰ类)、2.6%(Ⅳ类)。Ⅰ类储层流动单元多为高孔高渗、高孔中渗和中孔高渗储层,厚度范围为10～20m;Ⅱ类储层流动单元多为中孔高渗、高孔中渗和低孔高渗储层,厚度范围为10～47m;Ⅲ类储层流动单元多为中孔高渗、中孔低渗和低孔中渗储层,厚度范围为11～86m;Ⅳ类储层流动单元为低孔低渗和特低孔特低渗储层,厚度小于10m。火山岩储层流动单元发育和分布受火山机构相带和火山岩亚相的控制,表现为火山口-近火山口相带成为Ⅰ、Ⅱ类储层流动单元的机率最大,近源相带成为Ⅱ、Ⅲ类储层流动单元的机率最大,远源相带成为Ⅲ类和Ⅳ类储层流动单元的机率最大。原生气孔发育的上部亚相和粒间孔发育的热碎屑流亚相形成Ⅰ类储层流动单元的机率最大,原生孔隙不发育的空落亚相和下部亚相形成Ⅲ类储层流动单元的机率大。实现了火山岩储层流动单元的单井识别,为其三维模型的建立提供依据。

Volcanic reservoir flow units were classified based on four parameters,namely porosity,permeability,RQI and FZI, using cluster analysis on 388 samples of the Cretaceous volcanic rock of Yingcheng Formation(K_1y) in the area of well XS1 in central of the Songliao Basin.The flow units can be subdivided into four classes by comparing the cluster analysis results with the gas production of corresponding wells,ranking decreasingly from typeⅠ,Ⅱ,Ⅲto type-Ⅳ.Frequency of different level flow units show as follows,type-Ⅲ(39.2%),type-Ⅱ(33.2%),type-Ⅰ(25.0%) and type-Ⅳ(2.6%).Type-Ⅰ,the best of the flow units is composed mainly of the volcanic reservoirs with combination of high-porosity and high-permeability,or high-porosity and medium-permeability, or medium-porosity and high-permeability,and with a thickness between 10 to 20m.Type-Ⅱis predominantly medium-porosity and high-permeability,or high-porosity and medium-permeability,or low-porosity and high-permeability,and with a thickness varying from 10 to 47m.Type-Ⅲis mainly medium-porosity and high-permeability,or medium-porosity and low-permeability,or low-porosity and medium-permeability,and with a thickness of ca.11 to 86m.Type-Ⅳ,the worst of the flow units is generally composed of low porosity and low permeability,or ultra-low porosity and ultra-low permeability reservoirs,and shows thickness less than ten meters.Characteristics and distributions of the volcanic flow units are controlled by both volcanic edifices and subfacies.It is the fact that crater-near crater facies belt have the best potential to form type-Ⅰand type-Ⅱflow units,while proximal facies belt type-Ⅱand type-Ⅲand distal facies belt type-Ⅲand type-Ⅳ.The upper-effusive and the pyroclastics subfacies are most likely to develop flow unit of type-Ⅰ,because the former is rich in vesicle and the latter is rich in intergranular pore.Ash fall and lower-effusive subfacies are most likely to develop flow units of type-Ⅲand type-Ⅳ,because their primary pores and fractures are generally not well developed. Description and recognition of volcanic reservoir flow units are also presented.The work provides a foundation for 3-D modeling of the volcanic reservoir flow units.