海上少井条件下非均质储层复杂岩性三维地质建模--以东海A气田花港组厚砂储层为例

3D Geological Modeling of Complex Lithology of Heterogeneous Reservoirs With Few Wells Offshore--A Case Study of the Thick Sand Reservoir of Huagang Formation of Gas Field A in East Sea

东海盆地西湖凹陷中央背斜带花港组低渗储层具有强非均质性,主要发育有中孔中低渗特征的中砂岩相、粗砂岩相、低孔低渗特征的细砂岩相、粉砂岩相等8种岩性,其叠置组合对应辫状河三角洲前缘心滩坝、主河道、次级河道、水下分流间湾四种沉积微相。井区具有钻井少、井距大、地震反演资料多解性强等特征,运用常规建模方法难以表征井点实际揭示的储层非均质性。为了精细描述非均质储层平面、纵向上的空间展布特征,运用已钻井充足的分析化验资料并用多元测井识别方法识别出复杂岩性,通过垂向组合序列划分四种沉积微相,同时运用地震多属性与地层切片研究明确了相边界。用确定性方法和随机模拟相结合建立了精细相控下的岩性模型,并用基于岩性细化的孔渗关系来约束建立储层属性模型。结果表明,该方法建立的模型具有较高的可靠性,与地质认识较符合,为后期油藏数值模拟提供了精细框架,并指导了下一步开发方案的优化。

Low-permeability reservoirs of Huagang Formation in the central anticline zone of Xihu Sag in East China Sea Basin belongs to the strong heterogeneity.It mainly develops eight kinds of lithology,such as medium sandstone and coarse sandstone with medium porosity,medium and low permeability,and fine sandstone and siltstone with low porosity and low permeability,and their superimposed combination corresponds to four sedimentary microfacies in diara dam of braided river delta front,main channel,secondary channel,and underwater distributary bay.The well area is characterized by few drilling wells,large well spacing and strong multi-solution of seismic inversion data.It is difficult to characterize the heterogeneity of the reservoir actually revealed by the well point using conventional modeling methods.In order to accurately describe the spatial distribution characteristics of heterogeneous reservoirs in plane and longitudinal direction,the complex lithology was identified by analyzing and testing data of drilled wells and multi-component logging identification methods,and the sedimentary microfacies were divided into four types by vertical combination sequence,and the facies boundary was determined by seismic multi-attribute and stratigraphic section study.The lithologic model under fine phase control is established by the combination of deterministic method and stochastic simulation,and the porosity-permeability relationship based on lithology refinement is used to constrain the establishment of the reservoir attribute model.The results show that the model established by this method has high reliability and is more consistent with the geological understanding,which provides a fine framework for the simulation of reservoirs in the later period and guides the optimization of the overall development plan.