基于储层构型理论的致密砂岩成藏过程分析——以松辽盆地古龙向斜葡萄花油层为例

针对致密砂岩储层非均质性强和成藏过程复杂，利用岩心、岩石薄片、扫描电镜和实验分析测试等资料，基于储层构型理论的等级体系划分和成因单元识别，综合研究松辽盆地古龙向斜葡萄花油层的岩石学特征、物性特征、孔喉结构特征和成岩特征，进而对致密砂岩储层的致密史与成藏史时空耦合关系进行分析。结果表明：葡萄花油层由8种岩相成因单元、4种微相成因单元和1种亚相成因单元的3个等级体系级次组成；葡萄花油层砂岩类型主要为长石岩屑砂岩，粒度细，分选-磨圆中等，方解石充填为主，孔隙度平均值为7.63%，渗透率平均值为0.42×10^-3 μm²，孔隙类型以粒间溶蚀扩大孔为主，喉道类型主要发育收缩状、断面状和弯片状；葡萄花油层经历了两期胶结和一期溶蚀的成岩演化序列，目前处于中成岩阶段A期；葡萄花油层具有多期成藏和选择性充注的动态演化过程，得出向斜区油气富集的优质储层为水下河道微相、厚层席状砂微相及二者附近连通的薄层席状砂微相。

Hydrocarbon accumulation analysis of tight sandstone based on reservoir architecture theory-A case from Putaohua reservoir in the Gulong syncline,Songliao Basin

Tight sandstone reservoir is highly heterogeneous and its hydrocarbon accumulation process is complicated.The petrologic features,physical properties,pore throat structures and diagenesis of the Putaohua oil reservoir in Gulong syncline,Songliao Basin,were studied via a combination of core,thin section,SEM and experimental data.Then the spatio-temporal coupling relationship between the tightening history and hydrocarbon accumulation history of tight sandstone reservoir was analyzed based on the hierarchical system of architecture theory and the identification of genetic units.Results indicate that (1) hierarchically the Putaohua oil reservoir is composed of 8 lithofacies units,1 subfacies unit,and 4 microfacies units in terms of genesis;(2) the reservoir sandstone is mainly feldspar lithic sandstone with fine-grain size,medium sorting and rounding,mostly calcite cement filling,an average porosity of 7.63% and an average permeability 0.42×10^-3 μm².The majority of the pores are intergranular dissolution pores,developing shrinkage,fracture,and curved-plate throats;(3) the Putaohua oil reservoir is currently in Period A of the anadiagenetic stage after two periods of cementation and one period of dissolution during the diagenetic evolutionary history;(4) the oil enrichment of the Putaohua reservoir is attributed to the dynamic evolutionary process of multiphase accumulation and selective charging.And we come to the conclusion that microfacies of the underwater channel,thick sheet sandstone,and the interconnected thin sheet sandstone close to the above two areas are high-quality hydrocarbon-enriched reservoirs in the syncline.