低渗透储层类型划分及储层敏感性主控因素——以渤海海域古近系为例

利用岩石薄片鉴定、扫描电镜分析、储层敏感性实验等多种分析手段,对渤海海域低孔低渗储层的类型进行了详细划分,并对各类储层发育段的储层敏感性特征及其对应的黏土矿物特征、含量和分布规律进行了详细研究,分析了不同沉积条件对储层敏感性的影响。研究结果表明,渤海海域低渗透储层可划分为富高岭石型、富伊利石型、富绿泥石型、碳酸盐致密胶结型。通过将低渗透储层成因与储层敏感性建立关联,提出了储层敏感性主要受控于母岩类型、古气候条件、沉积微相3个因素：①母岩类型对研究区古近系碎屑岩储层演化起决定性影响。研究区主要具有3种类型的母岩：以中基性火山岩为母岩的碎屑岩储层、以中酸性火山岩为母岩的碎屑岩储层为火山碎屑-高岭石型、以变质岩为母岩的碎屑岩储层为伊利石型。②古气候条件对储层敏感性起到了重要影响。③沉积微相直接影响黏土矿物分异,沉积微相还间接影响后期成岩作用。

Low-permeability reservoir types classification and reservoir sensitivity controlling factors: a case study of Paleogene in Bohai Sea

Through the identification of thin sections, SEM analysis, sensitivity experiment of reservoirs and other analytical methods, this paper subdivides the types of low-porosity and low-permeability reservoirs in Bohai Sea, conducts a detailed study on the reservoir sensitivity of various reservoir-developed intervals and the characteristics, content and distribution of the corresponding clay minerals, and analyzes the effects of different sedimentary conditions on reservoir sensitivity. The results show that the low-permeability reservoirs in Bohai Sea are classified into kaolinite-rich type, illite-rich type, chlorite-rich type and carbonate dense cementation type. By establishing the relation between the genesis of low-permeability reservoirs with reservoir sensitivity, it is proposed that reservoir sensitivity is mainly controlled by three factors:parent rock type, paleoclimate conditions and sedimentary microfacies. First, parent rock type has a decisive influence on the evolution of the Paleogene clastic reservoirs in the study area. There are three main types of parent rocks, i.e., clastic reservoirs with intermediate-basic volcanic rocks as parent rocks, pyroclastic-kaolinite type of clastic reservoirs with intermediate-acidic volcanic rocks as parent rocks, and illite type of clastic reservoirs with metamorphic rocks as parent rocks. Paleoclimatic conditions have a vital impact on reservoir sensitivity. Sedimentary microfacies have a direct influence on the differentiation of clay minerals is directly affected and an indirect influence on the late diagenesis.