应用13口钻井的薄片鉴定、粒度分析、扫描电镜、锆石定年、物性等分析化验资料以及录井、测试资料,系统开展了惠州北凹珠海组、珠江组储层的发育特征、主控因素及商业产能下限研究.研究表明:①珠海组、珠江组发育大型海相三角洲—滨浅海沉积,储层主要为三角洲前缘水下分流河道中—粗粒洁净石英砂岩,其具有高成分成熟度和高结构成熟度,储集空间类型以原生粒间孔为主,局部富集次生溶孔、高岭石晶间孔,面孔率较高.②储层发育主要受"优质母源+有利相带+溶蚀作用"三元联控:研究区北部华南地块的变质岩+侵入岩作为优质母源决定了储层为石英含量高的砂岩类型,奠定了优质储层发育的基础,三角洲前缘主水道沉积水动力强,单砂体厚度大,砂岩粒度粗、泥质含量低,储层物性最好,建设性成岩作用(溶蚀作用)在一定程度上具有扩储增孔效应.③结合录井、测试资料确定惠州北凹油层的中—粗粒石英砂岩储层商业产能下限为3 800 m.

Huizhou Sag is an important place for crude oil production in the Zhuyi Depression.For a long time,research has been mainly focused on southwestern Huizhou Sag,whereas the study on northern Huizhou Sag is relatively weak and lacks data support,so the northern Huizhou Sag is still in the early stage of exploration.To promote the oil and gas exploration process in northern Huizhou Sag,the characteristics and development controlling factors of reservoirs in Zhuhai Formation and Zhujiang Formation in northern Huizhou Sag were systematically studied by using thin section,grain size analysis,scanning electron microscopy,zircon dating,reservoir properties and other data.The results show that the reservoir sandstone of Zhujiang Formation and Zhuhai Formation in the northern Huizhou Sag is mainly composed of medium to coarse grained quartz sandstone from delta front channels,with high compositional and structural maturity and low argillaceous content.Pores in the sandstone are dominated by primary intergranular pores,locally enriched with dissolution pores and kaolinite micropores.This sandstone has high porosity,and the maximum profitable depth is about 3 800 m.The reservoir quality of Zhujiang Formation and Zhuhai Formation in northern Huizhou Sag is mainly controlled by three factors:high-quality parent rocks,favorable sedimentary facies and constructive diagenetic process.The high-quality metamorphic and intrusive parent rocks in the South China block lead to high quartz content in the sandstone,laying the foundation for the development of high-quality reservoirs.The fluvial energy of delta front channels is high,resulting in the deposition of coarse grained sandstone,with low clay content and the best reservoir properties.Dissolution,as constructive diagenesis,can increase porosity,therefore increase reserves.