砂砾岩储层孔隙结构特征及定量评价

Pore structure characteristics and quantitative evaluation of glutenite reservoir

为了更好地研究砂砾岩储层孔隙结构特征及进行孔隙结构定量评价,以上乌尔禾组储层为研究对象,采用常规压汞、恒速压汞、铸体薄片等实验方法对孔隙结构特征及其影响因素进行了研究,综合测井资料建立了孔隙结构定量评价模型。镜下薄片资料表明,该区原生孔、次生孔均较发育,且主要在粒间孔、粒内溶孔中有荧光显示,油气主要赋存在次生孔隙中。根据常规压汞曲线形态特征,可将孔隙结构分为Ⅰ,Ⅱ,Ⅲ,Ⅳ等4种类型。结合恒速压汞实验和薄片资料表明,该层位孔喉配比关系多表现为大孔对应大喉、小喉和小孔对应小喉的特征,溶蚀作用对孔隙结构具有改善效果,而充填和压实作用是导致储层孔隙结构变差的主要因素。文中分析了压汞实验参数与综合物性指数的关系,通过引入孔隙结构指数,与声波时差、中子孔隙度、密度、泥质体积分数进行交会分析,利用多元回归方法建立了孔隙结构定量解释模型。经试油结果验证,该模型适用性强,与实验结果吻合。

In order to better study the pore structure characteristics of glutenite reservoirs and carry out quantitative evaluation of the pore structure, the Upper Wuerhe Formation reservoirs was taken as the research object, and the pore structure characteristics and its influencing factors were studied according to experimental methods such as conventional mercury injection, constant-speed mercury injection, and casting thin section. Then, the pore structure quantitative evaluation model was completed by comprehensive logging data. The microscopic data shows that the primary and secondary pores are developed in this area, and fluorescence is mainly displayed in intergranular pores and intragranular dissolved pores, which indicates that oil and gas is mainly present in the secondary pores. The pore structure is divided into four types from Ⅰto Ⅳ according to the conventional mercury intrusion curve morphology. Combining with constant-speed mercury injection and thin section data, the pore-throat ratios in this Formation are mostly characterized by large holes corresponding to large throats, and small throats and small holes corresponding to small throats.Dissolution can improve the pore structure, and filling and compaction are the main factors that lead to the deterioration of the pore structure of the reservoir. This paper analyzes the relationship between the mercury injection experiment parameters and the comprehensive physical property index, and introduces the pore structure index. By pore structure index combined with acoustic waves, neutrons, density, and shale content, the cross-plot analysis was carried out, and a quantitative interpretation model for pore structure was established using multiple regression methods.The oil testing shows that the model has strong applicability and is in agreement with the experimental results.