番禺B洼古近系甜点储层特征及发育机制

Characteristics and development mechanism of Paleogene sweet spots in Panyu B sub-sag

珠江口盆地番禺B洼探井A1井始新统恩平组储层埋深大于3500 m后个别点达到中渗,其主控因素与发育机制值得深入研究。基于铸体薄片、壁心及成像测井等各种资料,对A1井恩平组储层特征及影响因素进行分析,结果表明:储层岩性为长石石英砂岩,成分成熟度和结构成熟度较高,储集空间以剩余原生粒间孔为主,溶蚀孔不发育。沉积、成岩作用是番禺B洼恩平组储层物性的主要影响因素,三角洲平原亚相分流河道是形成甜点储层的主力相带,亦是其内在主控因素与物质基础;压实作用造成27.5%的原生孔隙丧失,为储层孔隙度降低的主要因素;胶结作用和溶蚀作用较弱。此外,基于成像测井资料所进行的构造作用分析发现,恩平组储层经历了较强的构造作用,现今地应力使储层物性得到进一步改善。

The reservoir from Eocene Enping formation of exploration well A1 in Panyu B sub-sag,Pearl River Mouth basin,reaches medium permeability at some points after burial depth is more than 3500 m,and its main controlling factors and development mechanism are worthy of further study.Based on the cast thin sections,sidewall cores and imaging logging data,the reservoir characteristics and influencing factors of Enping formation in well A1 are analyzed.The results show that the lithology of the reservoir is feldspathic quartz sandstone with high compositional maturity and structural maturity.The remaining primary intergranular pores are the main reservoir space,and the dissolution pores are not developed.Sedimentation and diagenesis are the main influencing factors of reservoir physical properties of Enping formation in Panyu B sub-sag.The distributary channel of delta plain sub-facies is the main facies belt for the formation of sweet spots reservoir,which is also the internal main controlling factor and material basis.Compaction results in the loss of 27.5%primary porosity,which is the main factor for the decrease of reservoir porosity.Cementation and dissolution are weak.In addition,the structural analysis based on the imaging logging data shows that the reservoir from Enping formation has experienced strong structural action,and the current in-situ stress has further improved the physical properties of the reservoir.